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OPTIMIZATION TOOLS & BASIC

TECHNIQUES

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KUWAIT GSM PROJECT

PROJECT DONE BY: FARAH ALBELUSHI Mentors: Engrs. Ishtiyaq & Shiras

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To

My family whose is supporting me always. All the nice people I have met in both Oman & Kuwait who are really a nice family.

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Abstract

The training aims to get the GSM knowledge and apply this knowledge in the optimization filed. Furthermore it includes site visiting and dealing with the network data to understand how the network is acting & to find the solution for different cases. Finally, I found the training very interesting & full of information besides feeling the how the real employment life is.

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Introduction This report contains seven chapters which represent the full details of what I achieved through two months and half as I join MOTOROLA Company in Oman & Kuwait which was my pleasure. Here is an overview of those chapters: Chapter 1: GSM (Global System for Mobile communications). Chapter 2: Optimization Tools. Chapter 3: Optimization Techniques. Chapter 4: Statistics. Chapter 5: RF Configuration. Chapter 6: Field experience Chapter 7: Tables

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Chapter 1: GSM (Global System for Mobile communications)

1- GSM History 2- Cellular systems

- The cellular structure. - Cluster. - Types of cells.

3- The transition from analog to digital technology - The capacity of the system of the system. - Compatibility with other systems. - Aspects of quality.

4- The GSM network - GSM network Architecture

• Mobile Station (MS) • The Base Station Subsystem (BSS) • The Network and Switching Subsystem (NSS) • The Operation and Support Subsystem (OSS)

- The geographical areas of the GSM network - The GSM functions

• Transmission • Radio Resources management (RR) • Mobility Management (MM) • Communication Management (CM) • Operation, Administration and Maintenance (OAM)

5- The GSM radio interface - Frequency allocation. - Multiple access scheme

• FDMA and TDMA • Channel structure • Burst structure • Frequency hopping

6- Discontinuous transmission (DTX)

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7- Timing advance(TA) 8- Power control 9- Discontinuous reception(DRX) 10- Multipath and equalization 11- The GSM functional layering 12- Different GSM module frequency ranges

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The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide. GSM was designed to be compatible with ISDN services. 1- GSM History The events in the development of GSM can be summarized in the following table. Table.1: The development of GSM.

Year Events

1982 CEPT establishes a GSM group in order to develop the standards for a pan-European cellular mobile system

1985 Adoption of a list of recommendations to be generated by the group

1986 Field tests were performed in order to test the different radio techniques proposed for the air interface

1987 TDMA is chosen as access method (in fact, it will be used with FDMA) Initial Memorandum of Understanding (MoU) signed by telecommunication operators (representing 12 countries)

1988 Validation of the GSM system 1989 The responsability of the GSM specifications is passed to the ETSI 1990 Appearance of the phase 1 of the GSM specifications 1991 Commercial launch of the GSM service

1992 Enlargement of the countries that signed the GSM- MoU> Coverage of larger cities/airports

1993 Coverage of main roads GSM services start outside Europe 1995 Phase 2 of the GSM specifications Coverage of rural areas

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2- Cellular systems 2.1- The cellular structure In a cellular system, the covering area of an operator is divided into cells. A cell corresponds to the covering area of one transmitter or a small collection of transmitters. The size of a cell is determined by the transmitter's power. The concept of cellular systems is the use of low power transmitters in order to enable the efficient reuse of the frequencies. In fact, if the transmitters used are very powerful, the frequencies can not be reused for hundred of kilometers as they are limited to the covering area of the transmitter. The frequency band allocated to a cellular mobile radio system is distributed over a group of cells and this distribution is repeated in all the covering area of an operator. The whole number of radio channels available can then be used in each group of cells that form the covering area of an operator. Frequencies used in a cell will be reused several cells away. The distance between the cells using the same frequency must be sufficient to avoid interference. The frequency reuse will increase considerably the capacity in number of users. In order to work properly, a cellular system must verify the following two main conditions:

The power level of a transmitter within a single cell must be limited in order to reduce the interference with the transmitters of neighboring cells. The interference will not produce any damage to the system if a distance of about 2.5 to 3 times the diameter of a cell is reserved between transmitters. The receiver filters must also be very preferment.

Neighboring cells can not share the same channels. In order to reduce the interference, the frequencies must be reused only within a certain pattern.

In order to exchange the information needed to maintain the communication links within the cellular network, several radio channels are reserved for the signaling information. 2.2- Cluster The cells are grouped into clusters. The number of cells in a cluster must be determined so that the cluster can be repeated continuously within the covering area of an operator. The typical clusters contain 4, 7, 12 or 21 cells. The number of cells in each cluster is very important. The smaller the number of cells per cluster is, the bigger the number of channels per cell will be. The capacity of each cell will be therefore increased. However a balance must be found in order to avoid the interference that could occur between neighboring clusters. This interference is produced by the small size of the clusters (the size of the cluster is defined by the number of cells per cluster). The total number of channels per cell depends on the number of available channels and the type of cluster used.

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2.3- Types of cells The density of population in a country is so varied that different types of cells are used:

• Macrocells • Microcells • Selective cells • Umbrella cells

1- Macrocells The macrocells are large cells for remote and sparsely populated areas. 2- Microcells These cells are used for densely populated areas. By splitting the existing areas into smaller cells, the number of channels available is increased as well as the capacity of the cells. The power level of the transmitters used in these cells is then decreased, reducing the possibility of interference between neighboring cells. 3- Selective cells It is not always useful to define a cell with a full coverage of 360 degrees. In some cases, cells with a particular shape and coverage are needed. These cells are called selective cells. A typical example of selective cells is the cells that may be located at the entrances of tunnels where coverage of 360 degrees is not needed. In this case, a selective cell with coverage of 120 degrees is used. 4- Umbrella cells A freeway crossing very small cells produces an important number of handovers among the different small neighboring cells. In order to solve this problem, the concept of umbrella cells is introduced. An umbrella cell covers several microcells. The power level inside an umbrella cell is increased comparing to the power levels used in the microcells that form the umbrella cell. When the speed of the mobile is too high, the mobile is handed off to the umbrella cell. The mobile will then stay longer in the same cell (in this case the umbrella cell). This will reduce the number of handovers and the work of the network. A too important number of handover demands and the propagation characteristics of a mobile can help to detect its high speed.

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Fig.1: Umbrella Cell.

3-The transition from analog to digital technology In the 1980s most mobile cellular systems were based on analog systems. The GSM system can be considered as the first digital cellular system. The different reasons that explain this transition from analog to digital technology are presented in this section. 3.1- The capacity of the system As cellular systems have experienced a very important growth. Analog systems were not able to cope with this increasing demand. In order to overcome this problem, new frequency bands and new technologies were proposed. But the possibility of using new frequency bands was rejected by a big number of countries because of the restricted spectrum (even if later on, other frequency bands have been allocated for the development of mobile cellular radio). The new analog technologies proposed were able to overcome the problem to a certain degree but the costs were too important. The digital radio was, therefore, the best option (but not the perfect one) to handle the capacity needs in a cost-efficiency way. 3.2- Compatibility with other systems such as ISDN The decision of adopting a digital technology for GSM was made in the course of developing the standard. During the development of GSM, the telecommunications industry converted to digital methods. The ISDN network is an example of this evolution. In order to make GSM compatible with the services offered by ISDN, it was decide that the digital technology was the best option. Additionally, a digital system allows, easily than an analog one, the implementation of future improvements and the change of its own characteristics. 3.3- Aspects of quality The quality of the service can be considerably improved using a digital technology rather than an analog one. In fact, analog systems pass the physical disturbances in radio transmission (such as fades, multipath reception, spurious signals or interferences) to the receiver. These disturbances decrease the quality of the communication because they produce effects such as fadeouts, crosstalks, hisses, etc. On the other hand, digital systems avoid these effects transforming the signal into bits. This transformation combined with other techniques, such as digital coding, improves the quality of the transmission. The improvement of digital systems comparing to analog systems is more noticeable under difficult reception conditions than under good reception conditions.

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4- The GSM network 4.1- GSM network Architecture The GSM technical specifications define the different entities that form the GSM network by defining their functions and interface requirements. The GSM network can be divided into four main parts: 1-The Mobile Station (MS). 2- The Base Station Subsystem (BSS). 3- The Network and Switching Subsystem (NSS). 4- The Operation and Support Subsystem (OSS).

Fig.2: Architecture of the GSM network.

• Mobile Station(MS)

A Mobile Station consists of two main elements:

The mobile equipment or terminal(ME) There are different types of terminals distinguished principally by their power and application: * The `fixed' terminals are the ones installed in cars. Their maximum allowed output power is 20 W. * The GSM portable terminals can also be installed in vehicles. Their maximum allowed output power is 8W. * The handhelds terminals have experienced the biggest success thanks to the weight and volume, which are continuously decreasing. These terminals can emit up to

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2 W. The evolution of technologies allows decreasing the maximum allowed power to 0.8 W.

The Subscriber Identity Module (SIM). The SIM is a smart card that identifies the terminal. By inserting the SIM card into the terminal, the user can have access to all the subscribed services. Without the SIM card, the terminal is not operational. The SIM card is protected by a four-digit Personal Identification Number (PIN). In order to identify the subscriber to the system, the SIM card contains some parameters of the user such as its International Mobile Subscriber Identity (IMSI). Another advantage of the SIM card is the mobility of the users. In fact, the only element that personalizes a terminal is the SIM card. Therefore, the user can have access to its subscribed services in any terminal using its SIM card.

• The Base Station Subsystem(BSS) The BSS connects the Mobile Station and the NSS. It is in charge of the transmission and reception. The BSS can be divided into two parts:

The Base Transceiver Station (BTS) or Base Station. The BTS corresponds to the transceivers and antennas used in each cell of the network. A BTS is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between one and sixteen transceivers depending on the density of users in the cell.

The Base Station Controller (BSC). The BSC controls a group of BTS and manages their radio resources. A BSC is principally in charge of handovers, frequency hopping, exchange functions and control of the radio frequency power levels of the BTSs.

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• The Network and Switching Subsystem (NSS) Its main role is to manage the communications between the mobile users and other users, such as mobile users, ISDN users, fixed telephony users, etc. It also includes data bases needed in order to store information about the subscribers and to manage their mobility. The different components of the NSS are described below.

The Mobile services Switching Center (MSC) It is the central component of the NSS. The MSC performs the switching functions of the network. It also provides connection to other networks.

The Gateway Mobile services Switching Center (GMSC) A gateway is a node interconnecting two networks. The GMSC is the interface between the mobile cellular network and the PSTN. It is in charge of routing calls from the fixed network towards a GSM user. The GMSC is often implemented in the same machines as the MSC.

Home Location Register (HLR) The HLR is considered as a very important database that stores information of the subscribers belonging to the covering area of a MSC. It also stores the current location of these subscribers and the services to which they have access. The location of the subscriber corresponds to the SS7 address of the Visitor Location Register (VLR) associated to the terminal.

Visitor Location Register (VLR) The VLR contains information from a subscriber's HLR necessary in order to provide the subscribed services to visiting users. When a subscriber enters the covering area of a new MSC, the VLR associated to this MSC will request information about the new subscriber to its corresponding HLR. The VLR will then have enough information in order to assure the subscribed services without needing to ask the HLR each time a communication is established. The VLR is always implemented together with a MSC; so the area under control of the MSC is also the area under control of the VLR.

The Authentication Center (AuC) The AuC register is used for security purposes. It provides the parameters needed for authentication and encryption functions. These parameters help to verify the user's identity.

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The Equipment Identity Register (EIR) The EIR is also used for security purposes. It is a register containing information about the mobile equipments. Like the HLR or the VLR, the EIR basically consists of a database, which maintains three lists:

The white list contains all the approved types of mobile stations. The black list contains those IMEIs known to be stolen to or be barred for

technical reasons. The gray list allows tracing of the related mobile stations.

Fig.3: Contents of EIR.

The GSM Interworking Unit (GIWU) The GIWU corresponds to an interface to various networks for data communications. During these communications, the transmission of speech and data can be alternated.

• The Operation and Support Subsystem (OSS) The OSS is connected to the different components of the NSS and to the BSC, in order to control and monitor the GSM system. It is also in charge of controlling the traffic load of the BSS. However, the increasing number of base stations, due to the development of cellular radio networks, has provoked that some of the maintenance tasks are transferred to the BTS. This transfer decreases considerably the costs of the maintenance of the system.

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4.2- The geographical areas of the GSM network As the cell is identified by its Cell Global Identity number (CGI), corresponds to the radio coverage of a base transceiver station. A Location Area (LA), identified by its Location Area Identity (LAI) number, is a group of cells served by a single MSC/VLR. A group of location areas under the control of the same MSC/VLR defines the MSC/VLR area. A Public Land Mobile Network (PLMN) is the area served by one network operator.

Fig.4: GSM network areas.

4.3- The GSM functions In this paragraph, the description of the GSM network is focused on the different functions to fulfill by the network and not on its physical components. In GSM, five main functions can be defined:

• Transmission. • Radio Resources management (RR). • Mobility Management (MM). • Communication Management (CM). • Operation, Administration and Maintenance (OAM).

• Transmission The transmission function includes two sub-functions:

The first one is related to the means needed for the transmission of user information.

The second one is related to the means needed for the transmission of signaling information.

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Not all the components of the GSM network are strongly related with the transmission functions. The MS, the BTS and the BSC, among others, are deeply concerned with transmission.

• Radio Resources management (RR) The role of the RR function is to establish, maintain and release communication links between mobile stations and the MSC. The elements that are mainly concerned with the RR function are the mobile station and the base station. However, as the RR function is also in charge of maintaining a connection even if the user moves from one cell to another, the MSC, in charge of handovers, is also concerned with the RR functions. The RR is also responsible for the management of the frequency spectrum and the reaction of the network to changing radio environment conditions. Some of the main RR procedures that assure its responsibilities are:

Channel assignment, change and release. Handover. Frequency hopping. Power-level control. Discontinuous transmission and reception. Timing advance.

Handover The user movements can produce the need to change the channel or cell, especially when the quality of the communication is decreasing. This procedure of changing the resources is called handover. Four different types of handovers can be distinguished:

Handover of channels in the same cell. Handover of cells controlled by the same BSC. Handover of cells belonging to the same MSC but controlled by different BSCs. Handover of cells controlled by different MSCs.

Handovers are mainly controlled by the MSC. However in order to avoid unnecessary signaling information, the first two types of handovers are managed by the concerned BSC (in this case, the MSC is only notified of the handover). The mobile station is the active participant in this procedure. In order to perform the handover, the mobile station controls continuously its own signal strength and the signal strength of the neighboring cells. The list of cells that must be monitored by the mobile station is given by the base station. The power measurements allow to decide which is the best cell in order to maintain the quality of the communication link. Two basic algorithms are used for the handover:

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1. The `minimum acceptable performance' algorithm. When the quality of the transmission decreases (i.e the signal is deteriorated), the power level of the mobile is increased. This is done until the increase of the power level has no

effect on the quality of the signal. When this happens, a handover is performed.

2. The `power budget' algorithm. This algorithm performs a handover, instead of continuously increasing the power level, in order to obtain a good communication quality.

• Mobility Management(MM) The MM function is in charge of all the aspects related with the mobility of the user, specially the location management and the authentication and security.

Location management When a mobile station is powered on, it performs a location update procedure by indicating its IMSI to the network. The first location update procedure is called the IMSI attach procedure. The mobile station also performs location updating, in order to indicate its current location, when it moves to a new Location Area or a different PLMN. This location updating message is sent to the new MSC/VLR, which gives the location information to the subscriber's HLR. If the mobile station is authorized in the new MSC/VLR, the subscriber's HLR cancels the registration of the mobile station with the old MSC/VLR. A location updating is also performed periodically. If after the updating time period, the mobile station has not registered, it is then deregistered. When a mobile station is powered off, it performs an IMSI detach procedure in order to tell the network that it is no longer connected.

Authentication and security The authentication procedure involves the SIM card and the Authentication Center. A secret key, stored in the SIM card and the AuC, and a ciphering algorithm called A3 are used in order to verify the authenticity of the user. The mobile station and the AuC compute a SRES using the secret key, the algorithm A3 and a random number generated by the AuC. If the two computed SRES are the same, the subscriber is authenticated. The different services to which the subscriber has access are also checked. Another security procedure is to check the equipment identity. If the IMEI number of the mobile is authorized in the EIR, the mobile station is allowed to connect the network. In order to assure user confidentiality, the user is registered with a Temporary Mobile Subscriber Identity (TMSI) after its first location update procedure. A list of IMEIs in the network is stored in the Equipment Identity Register (EIR). The status returned in response to an IMEI query to the EIR is one of the following: White-listed: The terminal is allowed to connect to the network. Grey-listed: The terminal is under observation from the network for possible problems.

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Black-listed: The terminal has either been reported stolen, or is not type approved (the correct type of terminal for a GSM network). The terminal is not allowed to connect to the network.

• Communication Management (CM) The CM function is responsible for:

1. Call control. 2. Supplementary Services management. 3. Short Message Services management.

- Call Control (CC) The CC is responsible for call establishing, maintaining and releasing as well as for selecting the type of service. One of the most important functions of the CC is the call routing. In order to reach a mobile subscriber, a user diales the Mobile Subscriber ISDN (MSISDN) number which includes:

A country code. A national destination code identifying the subscriber's operator. A code corresponding to the subscriber's HLR .

The call is then passed to the GMSC (if the call is originated from a fixed network) which knows the HLR corresponding to a certain MISDN number. The GMSC asks the HLR for information helping to the call routing. The HLR requests this information from the subscriber's current VLR. This VLR allocates temporarily a Mobile Station Roaming Number (MSRN) for the call. The MSRN number is the information returned by the HLR to the GMSC. Thanks to the MSRN number, the call is routed to subscriber's current MSC/VLR. In the subscriber's current LA, the mobile is paged: - Supplementary Services management The mobile station and the HLR are the only components of the GSM network involved with this function. - Short Message Services management In order to support these services, a GSM network is in contact with a Short Message Service Center through the two following interfaces:

The SMS-GMSC for Mobile Terminating Short Messages (SMS-MT/PP). It has the same role as the GMSC.

The SMS-IWMSC for Mobile Originating Short Messages (SMS-MO/PP).

• Operation, Administration and Maintenance (OAM)

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The OAM function allows the operator to monitor and control the system as well as to modify the configuration of the elements of the system. Not only the OSS is part of the OAM, also the BSS and NSS participate in its functions as it is shown in the following examples:

The components of the BSS and NSS provide the operator with all the information it needs. This information is then passed to the OSS which is in charge of analyzing it and control the network.

The self test tasks, usually incorporated in the components of the BSS and NSS, also contribute to the OAM functions.

The BSC, in charge of controlling several BTSs, is another example of an OAM function performed outside the OSS.

5- The GSM radio interface The radio interface is the interface between the mobile stations and the fixed infrastructure. It is one of the most important interfaces of the GSM system. One of the main objectives of GSM is roaming. Therefore, in order to obtain a complete compatibility between mobile stations and networks of different manufacturers and operators, the radio interface must be completely defined. The spectrum efficiency depends on the radio interface and the transmission, more particularly in aspects such as the capacity of the system and the techniques used in order to decrease the interference and to improve the frequency reuse scheme. The specification of the radio interface has then an important influence on the spectrum efficiency.

5.1-Frequency allocation Two frequency bands, of 25 MHz each one, have been allocated for the GSM system:

The band 890-915 MHz has been allocated for the uplink direction (transmitting from the mobile station to the base station).

The band 935-960 MHz has been allocated for the downlink direction (transmitting from the base station to the mobile station).

* Note: Then an increase by 10 MHz happened for EGSM as follows:

UL (880-915 MHz) DL (925-960 MHz)

But not all the countries can use the whole GSM frequency bands. This is due principally to military reasons and to the existence of previous analog systems using part of the two 25 MHz frequency bands.

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5.2-Multiple access scheme The multiple access scheme defines how different simultaneous communications, between different mobile stations situated in different cells, share the GSM radio spectrum. A mix of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA), combined with frequency hopping, has been adopted as the multiple access schemes for GSM.

• FDMA and TDMA Using FDMA, a frequency is assigned to a user. So the larger the number of users in a FDMA system, the larger the number of available frequencies must be. The limited available radio spectrum and the fact that a user will not free its assigned frequency until he does not need it anymore, explain why the number of users in a FDMA system can be "quickly" limited. On the other hand, TDMA allows several users to share the same channel. Each of the users, sharing the common channel, are assigned their own burst within a group of bursts called a frame. Usually TDMA is used with a FDMA structure. In GSM, a 25 MHz frequency band is divided, using a FDMA scheme, into 124 carrier frequencies spaced one from each other by a 200 KHz frequency band. Normally a 25 MHHz frequency band can provide 125 carrier frequencies but the first carrier frequency is used as a guard band between GSM and other services working on lower frequencies. Each carrier frequency is then divided in time using a TDMA scheme. This scheme splits the radio channel, with a width of 200 KHz, into 8 bursts. A burst is the unit of time in a TDMA system, and it lasts approximately 0.577 ms. A TDMA frame is formed with 8 bursts and lasts, consequently, 4.615 ms. Each of the eight bursts, that form a TDMA frame, are then assigned to a single user.

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Fig.5: FDMA/TDMA structure of GSM.

• Channel structure A channel corresponds to the recurrence of one burst every frame. It is defined by its frequency and the position of its corresponding burst within a TDMA frame. In GSM there are two types of channels:

The traffic channels used to transport speech and data information. The control channels used for network management messages and some channel

maintenance tasks.

Traffic channels (TCH) Full-rate traffic channels (TCH/F) are defined using a group of 26 TDMA frames called a 26-Multiframe. The 26-Multiframe lasts consequently 120 ms. In this 26-Multiframe structure, the traffic channels for the downlink and uplink are separated by 3 bursts. As a consequence, the mobiles will not need to transmit and receive at the same time which simplifies considerably the electronics of the system. The frames that form the 26-Multiframe structure have different functions:

24 frames are reserved to traffic. 1 frame is used for the Slow Associated Control Channel (SACCH). The last frame is unused. This idle frame allows the mobile station to perform

other functions, such as measuring the signal strength of neighboring cells. Half-rate traffic channels (TCH/H), which double the capacity of the system, are also grouped in a 26-Multiframe but the internal structure is different.

Control channels According to their functions, four different classes of control channels are defined:

1. Broadcast channels. 2. Common control channels. 3. Dedicated control channels. 4. Associated control channels.

1. Broadcast channels (BCH)

The BCH channels are used, by the base station, to provide the mobile station with the sufficient information it needs to synchronize with the network. Three different types of BCHs can be distinguished:

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The Broadcast Control Channel (BCCH), which gives to the mobile station the parameters needed in order to identify and access the network.

The Synchronization Channel (SCH), which gives to the mobile station the training sequence needed in order to demodulate the information transmitted by the base station

The Frequency-Correction Channel (FCCH), which supplies the mobile station with the frequency reference of the system in order to synchronize it with the network.

2. Common Control Channels (CCCH) The CCCH channels help to establish the calls from the mobile station or the network. Three different types of CCCH can be defined:

The Paging Channel (PCH). It is used to alert the mobile station of an incoming call.

The Random Access Channel (RACH), which is used by the mobile station to request access to the network.

The Access Grant Channel (AGCH). It is used, by the base station, to inform the mobile station about which channel it should use. This channel is the answer of a base station to a RACH from the mobile station.

3. Dedicated Control Channels (DCCH) The DCCH channels are used for message exchange between several mobiles or a mobile and the network. Two different types of DCCH can be defined:

The Standalone Dedicated Control Channel (SDCCH), which is used in order to exchange signaling information in the downlink and uplink directions.

The Slow Associated Control Channel (SACCH). It is used for channel maintenance and channel control.

4. Associated Control Channels The Fast Associated Control Channels (FACCH) replaces all or part of a traffic channel when urgent signaling information must be transmitted. The FACCH channels carry the same information as the SDCCH channels.

• Burst structure As it has been stated before, the burst is the unit in time of a TDMA system. Four different types of bursts can be distinguished in GSM:

The frequency-correction burst is used on the FCCH. It has the same length as the normal burst but a different structure.

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The synchronization burst is used on the SCH. It has the same length as the normal burst but a different structure.

The random access burst is used on the RACH and is shorter than the normal burst.

The normal burst is used to carry speech or data information. It lasts approximately 0.577 ms and has a length of 156.25 bits.

Fig.6: Structure of the 26-Multiframe, the TDMA frame and the normal burst.

In the previous figure

The tail bits (T) are a group of three bits set to zero and placed at the beginning and the end of a burst. They are used to cover the periods of ramping up and down of the mobile's power.

The coded data bits correspond to two groups, of 57 bits each, containing signaling or user data.

The stealing flags (S) indicate, to the receiver, whether the information carried by a burst corresponds to traffic or signaling data.

The training sequence has a length of 26 bits. It is used to synchronize the receiver with the incoming information, avoiding then the negative effects produced by a multipath propagation.

The guard period (GP), with a length of 8.25 bits, is used to avoid a possible overlap of two mobiles during the ramping time.

• Frequency hopping

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The propagation conditions and therefore the multipath fading depend on the radio frequency. In order to avoid important differences in the quality of the channels, the slow frequency hopping is introduced. The slow frequency hopping changes the frequency with every TDMA frame. A fast frequency hopping changes the frequency many times per frame but it is not used in GSM. The frequency hopping also reduces the effects of co-channel interference. There are different types of frequency hopping algorithms. The algorithm selected is sent through the Broadcast Control Channels. Even if frequency hopping can be very useful for the system, a base station does not have to support it necessarily. On the other hand, a mobile station has to accept frequency hopping when a base station decides to use it. 6- Discontinuous transmission (DTX) This is another aspect of GSM that could have been included as one of the requirements of the GSM speech codec. The function of the DTX is to suspend the radio transmission during the silence periods. This can become quite interesting if we take into consideration the fact that a person speaks less than 40 or 50 percent during a conversation. The DTX helps then to reduce interference between different cells and to increase the capacity of the system. It also extends the life of a mobile's battery. The DTX function is performed thanks to two main features:

• The Voice Activity Detection (VAD), which has to determine whether the sound represents speech or noise, even if the background noise is very important. If the voice signal is considered as noise, the transmitter is turned off producing then, an unpleasant effect called clipping.

• The comfort noise. An inconvenient of the DTX function is that when the signal is considered as noise, the transmitter is turned off and therefore, a total silence is heard at the receiver. This can be very annoying to the user at the reception because it seems that the connection is dead. In order to overcome this problem, the receiver creates a minimum of background noise called comfort noise. The comfort noise eliminates the impression that the connection is dead.

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7- Discontinuous reception (DRX) It is a method used to conserve the mobile station's power. The paging channel is divided into subchannels corresponding to single mobile stations. Each mobile station will then only 'listen' to its subchannel and will stay in the sleep mode during the other subchannels of the paging channel. 8- Multipath and equalization At the GSM frequency bands, radio waves reflect from buildings, cars, hills, etc. So not only the 'right' signal (the output signal of the emitter) is received by an antenna, but also many reflected signals, which corrupt the information, with different phases. An equalizer is in charge of extracting the 'right' signal from the received signal. It estimates the channel impulse response of the GSM system and then constructs an inverse filter. The receiver knows which training sequence it must wait for. The equalizer will then, comparing the received training sequence with the training sequence it was expecting, compute the coefficients of the channel impulse response. In order to extract the 'right' signal, the received signal is passed through the inverse filter. 7- Timing advance (TA) The timing of the bursts transmissions is very important. Mobiles are at different distances from the base stations. Their delay depends, consequently, on their distance. The aim of the timing advance is that the signals coming from the different mobile stations arrive to the base station at the right time. The base station measures the timing delay of the mobile stations. If the bursts corresponding to a mobile station arrive too late and overlap with other bursts, the base station tells, this mobile, to advance the transmission of its bursts. For technical reasons, it is necessary that the MS and the BTS do not transmit simultaneously. Therefore, the MS is transmitting three timeslots after the BTS. The time between sending and receiving data is used by the MS to perform various measurements on the signal quality of the receivable neighbor cells. As shown in the figure below, the MS actually does not send exactly three timeslots after receiving data from the BTS. Depending on the distance between the two, a considerable propagation delay needs to be taken into account. That propagation delay, known as timing advance (TA), requires the MS to transmit its data a little earlier as determined by the three timeslots delay rule.

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Fig.7.The uplink & downlink shift.

10- Power control At the same time the base stations perform the timing measurements, they also perform measurements on the power level of the different mobile stations. These power levels are adjusted so that the power is nearly the same for each burst. A base station also controls its power level. The mobile station measures the strength and the quality of the signal between itself and the base station. If the mobile station does not receive correctly the signal, the base station changes its power level.

11-The GSM functional layering The layering of GSM functions is partially based on the seven layer model for open systems interconnection suggested by the ISO. Each layer performs a specific set of functions that are isolated and enhances those performed by the lower layers. This philosophy facilitates a modular approach to implementation. The functions occurring at one layer have only limited interaction with those at another. This provides a degree of flexibility for future improvements without redesigning the entire system.

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Fig.8: GSM functional layering.

- Physical layer Layer 1 comprises the physical channel layer and is concerned with transmitting and receiving coded information symbols over the radio link. Layer 1 features include the TDMA frame structure and frequency hopping. - Transport layer Layer 2 features include the multiplexing and demultiplexing of logical channels. - Management layer Layer 3 provides for the three major management functions as can be seen from the following tables.

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Table.2: Radio Resource Management Messages.

Name Direction Description CHANnel REQuest

CHAN_REQ is a request of an MS for a channel when in the idle state. Although only 1 byte long this message already contains the reason for the connection request (answer to PAGING, Emergency Call, etc.) and an identifier for the channel type that the MS prefers. The CHAN_REQ has no hexadecimal message type, because the message does not conform to the regular format and is sent via an access burst.

HaNDover ACCess

The MS sends consecutive HND_ACC messages on a new traffic channel for every handover (synchronized and nonsynchronized). The only exception is the intra-BTS handover via ASS_CMD. Like the CHAN_REQ, the HND_ACC does not follow the standard format and is sent in an access burst to the BTS. The handover reference is the only information that HND_ACC contains and is assigned with the HND_CMD message to allow for identification of the correct MS during BTS access.

PARTial RELease

When an MS has activated two radio channels at the same time, and CC wants to release one channel, a PART_REL message is sent. For the time being, this is defined only for two halfrate channels.

CHANnel RELease

The CHAN_REL message is used when a connection is disconnected, to release the radio resources on the air interface. Cause 0 is used for normal clearing; for abnormal clearing, for instance, cause 1 is used.

PARTial RELease COMplete

With this message, the MS confirms receipt and processing of a PART_REL message.

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MEASurement REPort

MEAS_REP transfers the current measurement results of the MS to the BTS (uplink measurements). These measurements contain the sending levels of the serving cell and of the neighboring cells. In the case of an active connection, a MEAS_REP is sent to the BTS every 480 ms via the SACCH. The BTS forwards the MEAS_REP to the BSC, embedded in its own measurement results

CLASSmark CHANGE

The MS sends this message when the classmark changes (e.g., when a handheld phone is connected to a booster in a car) or when a request is made by the network(CLASS_ENQ) It contains the current technical capabilities of the MS.

CHANnel MODe MODify ACKnowledge

The MS confirms with CHAN_MOD_MOD_ACK the change to another transmission mode that was requested with CHAN_MOD_MOD.

PAGing RE-Quest Type 1 PAGing REQuest Type 2 PAGing REQuest Type 3

Three different PAG_REQ messages were defined for activation of the MS in the case of an MTC. The difference between the messages lies simply in the number of MSs that can be paged simultaneously with one message (PAG_REQ 1 allows paging of two MSs, PAG_REQ 2 allows paging of three MSs, PAG_REQ 3 allows paging of four MSs). Consequently, the according number of IMSIs/TMSIs are contained in a PAG_REQ. Note that the IMSI is not contained in the PAG_REQ if a TMSI is assigned, even though the PAGING message contains both parameters.

PAGing Re-SPonse

PAG_RSP is the first message sent by the MS on the SDCCH to the BTS in an MTC. PAG_RSP corresponds to the CM_SERV_REQ message of a MOC.

HaNDover FAIlure

After an unsuccessful handover initiated by a HND_CMD, the MS sends a HND_FAI over the still existing connection to the old BTS.

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ASSignment COMplete

The MS confirms that it successfully changed to the (new) traffic channel, that is, the one previously assigned by as ASS_CM message.

HaNDover CoMmanD

Channel assignment for a handover in which the BTS changes is always performed with HND_CMD; in an intra-BTS handover, the HND_CMD can be used. The message contains a description of the new traffic channel and the handover reference.

HaNDover COMplete

After successful handover initiated by a HND_CMD, the MS responds to the BTS with a HND_COM.

ASSignment CoMmanD

Assignment of a traffic channel in case of an intra-cell handover or during call setup.

ASSignment FAIlure

The MS was not successful in changing to the channel specified in the ASS_CMD message. It has, therefore, changed back to the previously used channel and reports the failed access in a ASS_FAI message.

CIPHering MODe COMplete

The MS confirms that a CIPH_MOD_CMD was received and that it has changed to the cipher mode.

CIPHering MODe CoMmanD

The content of the CIPH_MOD_CMD message originates from the VLR. It is part of the ENCR_CMD message on the Abis-interface. The BTS informs the MS with CIPH_MOD_CMD that all data in both, uplink, and downlink are to be encrypted. The only content is the information as to which encryption algorithm A5/X shall be used.

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IMMediate ASSignment REJect

The BSC may answer a CHAN_REQ message with IMM_ASS_REJ if no SDCCHs are available. In this case, no channel is assigned and the MS is informed about a waiting period, during which it may not send a subsequent CHAN_REQ.

IMMediate ASSignmnent CoMmanD

The BSC uses the IMM_ASS_CMD to assign an SDCCH to the MS after a CHAN_REQ message was received. IMM_ASS_CMD is always sent on an AGCH. The message has to be distinguished from ASS_CMD, which is used to assign a traffic channel.

Table.3: Mobility Management Messages.

Name Direction Description IMSI DETach INDication

If IMSI attach/detach is allowed in the PLMN, then every time the MS is switched off the MS sends a IMSI_DET_IND to the MSC/VLR. This allows to more quickly reject an incoming call, or apply secondary call treatment, i.e., without sending PAG_REQ first.

LOCation UPDating ACCept

The MSC/VLR confirms a successful Location Update with a LOC_UPD_ACC. In some cases the LOC_UPD_ACC is used to assign a new TMSI as well.

LOCation UPDating REJect

If a Location Update is not successful, (e.g., HLR is not reachable, IMSI or TMSI are unknown, etc.), then the MSC/VLR terminates the process with a LOC_UPD_REJ.

LOCation UPDating REQuest

The MS sends the LOC_UPD_REQ to the MSC/VLR when it changes the Location Area, when Periodic Location Update is active, and when the MS is switched on again (with active IMSI attach/detach). LOC_UPD_REQ is part of the Location Update procedure.

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AUTHentication REJect

The AUTH_REJ message is used to inform the MS that authentication was not successful if the MSC/VLR found that the result for SRES from the MS was incorrect.

AUTHentication REQuest

The MSC/VLR sends an AUTH_REQ message during connection setup, in order to authenticate the MS. The only parameter is RAND.

AUTHentication ReSPonse

Answer to AUTH_REQ. It contains the authentication result SRES, which was determined by applying the values of Ki and RAND to the algorithm A3.

IDENTity REQest

Although IDENT_REQ generally allows to request all three identification numbers from the MS, (IMSI, TMSI, and IMEI,) it is typically used by the Equipment Identity Register to request the IMEI only.

IDENTity ReSPonse

IDENT_RSP is the answer to IDENT_REQ. The MS provides the network with the requested identification numbers (IMSI, TMSI, IMEI), which were requested in the IDENT_REQ message.

CM SERVice ACCept

Is used by the MSC if ciphering is not active or after the establishment of a second simultaneous CC connection. CM_SERV_ACC confirms to the MS that the service request, sent to the MSC in a CM_SERV_REQ message, was processed and accepted.

CM SERVice REJect

The service request in which the MS has sent in a CM_SERV_REQ message is rejected by the MSC. The reason (e.g., overload) is provided.

CM SERVice ABOrt

Is sent if a MS wants to terminate a MM connection. The CM_SERV_ABO can only be sent during a very narrow time window, because this message can only be used prior to the fist CC message sent.

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CM SERVice REQuest

The MS sends a CM_SERV_REQ at the beginning of every mobile originated connection in order to provide its identity (IMSI/TMSI) to the NSS, and to specify the service request in more detail (activation SS, MOC, Emergency Call, and SMS).

MM STATUS

If one side receives a message for Mobility Management, which contains a protocol error in Layer 3, then an MM STATUS message with the respective error cause is sent. This kind of protocol error may be caused by bit errors on the Air-interface.

Table.4: Call Control Messages.

Name Direction Description ALERTing

The MSC sends this message in case of a Mobile Originating Call to the MS. In case of a Mobile Terminating Call, the MS sends an ALERT to the MSC. ALERT corresponds to the Address Complete Message (ACM) of ISUP and is responsible for the generation of a ring back tone at the receiving end. ALERT is always sent to that side of the call, which initiated it. This is important for protocol analysis.

CALL PROCeeding

Is sent by the MSC in case of a Mobile Originating Call, in order to inform the MS that the address information which the MS has sent to the MSC in the SETUP message was received and processed. From the perspective of the MSC, CALL_PROC can be regarded as a confirmation that the ISUP Initial Address Message (IAM) was sent. The consequence for the MS is that the MSC does not need, or is not even able to process additional address information.

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SETUP

When initiating a Mobile Originating Call, this message is sent by the MS to the MSC. The most important information are the address information of the called party and the type of connection, which is requested (Bearer Capabilities). In case of a Mobile Terminating Call, the MSC sends a SETUP message to the MS. When CLIP (Calling Line Identification Presentation) is active for the called party and is not restricted by the calling party, then the SETUP message also contains the directory number of the caller. The SETUP message is, furthermore, used to activate the Call Waiting tone (Supplementary Service) at the MS.

CONnect

The MSC sends this message during a Mobile Originating Call to the MS, to indicate that the connection was successfully established. The MS receiving the CON message corresponds to the MSC receiving the ISUP Answer Message (ANM). The MS sends a CON message to the MSC in case of a mobile terminating call, as soon as the called party accepts the call.

CALL CONFirmed

After receiving a SETUP message during a Mobile Terminating Call scenario, the MS confirms to the MSC in a CALL_CONF that it is able to establish the requested connection (Bearer Service, halfrate/fullrate, baud rate, etc.).

CONnect ACKnowledge

CON_ACK is acknowledgment for a CON message. A call set up is regarded to be successful only after the message was sent. In particular charging starts typically with the CON_ACK message.

DISConnect

Is used either by the MSC or the MS, to terminate an existing CC connection. The DISC message always contains a cause value, which indicates the reason why the connection was disconnected.

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RELease COMplete

REL_COM is the answer to a REL message and the acknowledgment that the CC resources have been released. REL_COM is always sent by that side, which had previously sent the DISC message. Like for REL, also for REL_COM there exists an ISUP message with the same name.

RELease

Because of the fact that signaling in GSM is related to ISDN, there are some similarities in the CC protocol between the two. The REL message corresponds directly to an ISUP message with the same name, which in the case of ISDN is responsible for terminating a connection. The same functionality provides this message in GSM, namely to release the CC resources.

12-Different GSM module frequency ranges

• Primary GSM900 frequencies This section lists all the frequencies used in Primary GSM (PGSM), with their channel numbers in both decimal and hexadecimal notation.GSM900 systems use radio frequencies between 890-915 MHz for receive and between 935-960 MHz for transmit, as shown in Figure 2-21. RF carriers are spaced every 200 kHz, allowing a total of 124 carriers for use. Other frequencies between 917 MHz and 935 MHz are available for use by other (non-GSM) cellular systems. A guard band of 2 MHz of unused frequencies between 915 and 917 MHz protects against interference between the transmitted and received frequencies. Guard bands between GSM and non-GSM frequencies depend on the prevailing standards in the country concerned and on agreements reached by network operators. Any such guard bands are likely to be quite small; for example, the last carrier of the frequency range may be left unused. Transmit and receive frequencies are separated by 45 MHz, and this fixed frequency gap reduces the possibility of interference.

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Fig.9: GSM900 frequency range.

• EGSM frequencies This section lists all the extra frequencies used in Extended GSM (EGSM), with their channel numbers in both decimal and hexadecimal notation. EGSM also uses all frequencies listed in PGSM frequencies and PGSM channels. Figure. 10 shows that further 10MHz of bandwidth on both transmit and receive allocations have now extended the GSM900 bandwidth.

Fig.10: EGSM frequency range.

• DCS1800 frequencies This section lists the frequencies used in Digital Cellular System (DCS) 1800, with their channel numbers in both decimal and hexadecimal notation. DCS1800 systems use radio frequencies between 1710-1785 MHz for receive and between 1805-1880 MHz for transmit, as shown in Figure.11. RF carriers are spaced every 200 kHz, allowing a total of 373 carriers for use, with one used as a guard band. A guard band of 20 MHz of unused frequencies between 1785 and 1805 MHz protects against interference between the transmitted and received frequencies. There is a 100 kHz guard band between 1710.0

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MHz and 1710.1 MHz and between 1784.9 MHz and 1785.0 MHz for receive, and between 1805.0 MHz and 1805.1 MHz and between 1879.9 MHz and 1880.0 MHz for transmit. Transmit and receive frequencies are separated by 95 MHz, and this fixed frequency gap reduces the possibility of interference.

Fig.11: DCS1800 frequency range.

• PCS1900 frequencies This section lists the frequencies used in PCS1900, with their channel numbers in both decimal and hexadecimal notation. PCS1900 systems use radio frequencies between 1850-1910 MHz for receive and between 1930-1990 MHz for transmit, as shown in Figure.12. RF carriers are spaced every 200 kHz, allowing a total of 299 carriers for use. A guard band of 20 MHz of unused frequencies between 1910 and 1930 MHz protects against interference between the transmitted and received frequencies. There is a 100 kHz guard band between 1850.0 MHz and 1850.1 MHz and between 1909.9 MHz and 1910.0 MHz for receive, and between 1930.0 MHz and 1930.1 MHz and between 1989.9 MHz and 1990.0 MHz for transmit. Transmit and receive frequencies are separated by 80 MHz, and this fixed frequency gap reduces the possibility of interference.

Fig.12: PCS1900 frequency range.

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Chapter 2: Optimization Tools

1- TEMS (Test Mobile System). - TEMS over view. - TEMS menu tab. - Generating Logfiles Report. - Exporting Logfiles. - Drive test analysis. 2- MARS (Motorola Reporting and Analyzing System). - Introduction. - MARS main features. - Scheduling a data load. - Introduction to scheduled reports.

3- CTP (Call Trace Platform).

- Introduction. - CTP analysis.

4- Actix (Analyzer).

- An over view.

5- MapInfo. - Introduction. - MapInfo usage. - Thematic Mapping.

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1- TEMS (Test Mobile System)

1.1- TEMS overview

• Hardware: TEMS phone. GPS (Global Positioning System) unit. PC with 2 Serial ports. DC-AC Power Inverter.

• Software: TEMS R4.1. TEMS 98(DUAL BAND 900/1800). TEMS 2.0(EGSM, MapInfo, License File for individual user). TEMS 4.0(Lisence is in TEMS Phone hardware). TEMS 4.1.1 ( New ver. With fix of bugs in ver. 4.0 ). TEMS 5.0 (EDGE Enhanced Data Rates For Global Evaluation). It is an air interface test tool for real-time diagnostics. It lets you monitor voice channels as well as data transfer over GPRS. In GSM it can be run into two different modes:

• Drive testing mode. Information is read from one or several mobile stations and a GPS unit.

• Analysis mode. Information is read from a logfiles. The two modes are mutually exclusive. At the beginning of a session, the application is in analysis mode. As soon as you connect external equipment, however, it switches to drive testing mode and remains in this mode as long as some external device is connected. Disconnecting all external devices returns the application to analysis mode.

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1.2- TEMS menu tab The Menu tab lists most types of windows that are available in TEMS Investigation. They are divided into three categories as can be seen from the figure below.

Fig.13: TEMS menu tab.

• Presentation Folder Here are some examples of this folder * GSM Status Windows 1- Serving + Neighbors Shows BSIC, ARFCN, RxLev, and some further parameters for the serving cell and its neighboring cells, with the serving cell on top and the neighbors below it, sorted by signal strength in descending order.

Menu Tab

Control Folder

•Cell Definition. • General. • Port Configuration. • Audio Indications for Events.

•Command Control. • Handset Control. • Layer 3 Control. • Channel Verification.

•GSM. • Data Services. • Signaling. • Positioning.

Configuration Folder

Presentation Folder

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2- Radio Parameters Presents a collection of vital facts about the status of the radio link (current BCCH, signal strength, speech quality, and so on). 3- Current Channel Shows information elements relating to the channel currently used. It also shows current time. 4- Hopping Channels Shows ARFCN, RxLev and C/I for all channels currently in the hopping list. 5- Line Chart This is the standard line chart for ordinary GSM information elements.

Fig.14. GSM status window.

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Note: In the line chart SQI is better than RxQual

Traditionally, speech quality in GSM networks is measured by means of the RxQual parameter (which is also available in TEMS Investigation). RxQual, however, suffers from a number of drawbacks which make it an unreliable indicator of speech quality. SQI is a more sophisticated measure which is dedicated to reflecting the quality of the speech (as opposed to radio environment conditions). This means that when optimizing the speech quality in your network, SQI is the best criterion to use. RxQual is obtained by transforming the bit error rate (BER) into a scale from 0 to 7 (see GSM 05.08). In other words, RxQual is a very basic measure: it simply reflects the average BER over a certain period of time (0.5 s). By contrast, a listener's assessment of speech quality is a complex process which is influenced by many factors. Some of these, all of which RxQual fails to take into account, are the following:

The distribution of bit errors over time. For a given BER, if the BER fluctuates very much, the perceived quality is lower than if the BER remains rather constant most of the time. Different channel conditions give rise to radically different BER distributions. However, since RxQual just measures the average BER, it cannot capture this

Frame erasures. When entire speech frames are lost, this affects the perceived quality in a very negative way.

Handovers. Handovers always cause some frames to be lost, which generally gives rise to audible disturbances. This does not show at all in RxQual, however, since during handovers BER measurements are suppressed.

The choice of speech codec. The general quality level and the highest attainable quality vary widely between speech codecs. Moreover, each codec has its own strengths and weaknesses as regards types of input and channel conditions.

In short, RxQual fails to capture many phenomena that have a decisive influence on a listener's judgment of speech quality. Using RxQual for optimization of speech quality in the network thus leads to suboptimal results.

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* Interference Status Windows 1- C/A Shows the interference from adjacent channels. 2- C/I Shows the carrier-over-interference ratio, i.e. the ratio between the signal strength of the current serving cell and the signal strength of interfering signal components. If frequency hopping is used, the window shows the entire hopping list sorted by ascending C/I: the currently worst channel is at the top. 3- Interference Line Chart The advantage of the line chart is that it maintains a history and allows you to study interference patterns over a period of time. To the Interference Line Chart has also been added a pane with RxLev and C/I, which are instructive to correlate with the result of the interference scan, especially if you have been moving around while performing it.

Fig.15. Interference status window.

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* Signaling status window 1- Events. This window lists all events that occur, both predefined and user-defined. 2- Layer 3 Messages. This window lists Layer 3 messages, including those pertaining to GPRS. 3- Mode Reports This window lists (TEMS-specific) reports from the mobile station concerning its status.

Fig.16. Signaling status window.

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* Positioning 1- Map The Map window is used to display a map of your test area and present your drive test route graphically on this map. Data on cells, events, and information elements are shown along the route in symbolic form; numerical values can also be easily accessed. Like the other presentation windows, the Map window is fully user-configurable. Map files used in TEMS Investigation must be in either MapInfo, bitmap, or TIF format. Note also that to be able to plot measurements on a map, TEMS Investigation must have access to positioning data. 2-GPS This window shows information from the GPS unit. Exactly what information is shown depends on the type of GPS. If GPS coverage is temporarily lost, for instance when driving through a tunnel, TEMS Investigation will reconstruct the missing route segment by representing it as a straight line. The accumulated measurements are distributed along this line according to their time stamps.

Fig.17. Positioning status window.

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On the map you have: - A layer which is a set of data from a particular category that is displayed in the map window. There are two types of layers: map layers, which build up the map itself, and presentation layers, which contain information relating to the cellular network. A map layer may, for example, consist of all the roads or all the water areas on the map. A presentation layer contains one or several themes, all of the same main type. One presentation layer is predefined for each main type of theme; additional layers can be defined by the user. Them: A theme is a component of a presentation layer. There are three main types of theme: information element (IE) themes, consisting of a package of settings that describe how to present a set of information elements (at most three); event themes, presenting an event; and cell themes (of which there are three subtypes), presenting cell site information. - A label is a text string that belongs to a map and can be displayed on it.

- A GeoSet (file extension .gst) is a special type of workspace used for map layers. A GeoSet contains settings regarding layer order, projections, zoom levels, labels, colors, etc.

Fig.18: adding map layers.

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• Configuration Folder 1- Cell Definition TEMS Investigation can present information about individual cells in the GSM network. In particular, it is possible to draw cells on maps and to display cell names in various windows. Cell information is also made use of in logfile reports. Cell information can be provided in two ways:

- In a plain-text XML file (*.xml) whose format is common to TEMS Investigation and TEMS Cell Planner.

- In a file with a plain-text, TEMS Investigation GSM specific format (*.cel). 2- General To make a cell definition file active, it must be loaded in the General window. On loading the cell definition file, its contents are automatically displayed in the Cell Definition window. 3- Audio Indications for Events For each event you can specify an audio signal to be played when the event occurs. This is useful if you are performing a drive test on your own and need to keep your eyes on the road.

Fig.19: Configuration Folder.

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• Control Folder

1- Command Sequences Command sequences are used to automate testing. They allow you to prerecord all the commands to be given to the mobile stations during a drive test. The command sequence can govern both voice calls and data transfer sessions.

- The voice call functionality includes control of cell reselection and handover behavior, as well as C/A and C/I measurements. If you are using several mobiles, you can make them call each other automatically.

- The data service testing functionality supports FTP, HTTP, e-mail, and Ping sessions involving one or several TEMS mobiles (T68, T62u, or R520m).

2- Manual Handset Control By opening a Handset Control window from the Navigator, you get a clickable image mirroring the user interface of the mobile station. This window can be used for giving input to the mobile in exactly the same way as when using the real keypad. 3- Control of Layer 3 Messages TEMS Investigation provides a function for monitoring and manipulating Layer 3 messages exchanged between the mobile station and the network. This is accomplished by: - Applying operations to individual Layer 3 messages.

- Arranging these operations in an operation sequence. 4- Channel Verification The Channel Verification utility allows you to check the availability of a set of traffic channels, typically those used in one cell or a set of cells. TEMS Investigation lets one or several TEMS mobiles make calls repeatedly on the chosen channels until all timeslots of interest have been tested.

Fig.19.Control Folder.

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1.3 - Generating Logfiles Report From one or several logfiles you can generate a report in HTML format which summarizes the data in the logfiles. The overall structure of the HTML file appears from the following figure.

Fig.20. Logfile overall structure.

Fig.21. Generating Logfile Report.

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The Report In the report is an important feature of the TEMS since it gives the optimizer a full overview of the drive test for a big number of logfiles as he can find the summerized information for the logfiles such as:

• Logfile information table. • There is also the events table. • Distribution graphs of all logfiles. As can be seen from the figures below.

Fig.22: Logfile information table.

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Fig.23: The events table.

Fig.24: Two Distribution graphs of all logfiles.

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1.4-Exporting Logfiles

Logfiles can be exported in the following formats:

Text file with tab delimited data (suitable for processing in, for example, a spreadsheet application). TEMS Automatic logfiles, too, can be exported in this format. The text export format for logfiles uses an ASCII representation with tab delimited data. The default file extension is .fmt.

Fig.25. Exporting logfiles.

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1.5-Drive test analysis In the drive testing there are many problems come out which can be observed easily using TEMS applications. As can be seen from the discussed cases.

- Undecoded BCCH

Description:

BSICs can’t be decoded in 5s Usually consider 3 strongest neighbors

Reason: GCLK shift, only decode same site BSICs Channel interference. Non-BCCH carrier, no dedicated spectrum for BCCH.

Fig.26. Undecodd BCCH.

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- No Handover Description:

Neighbor BSIC is decoded and COMMON handover requirement is fulfilled but there is never a handover.

Reason: Missing neighbor

• No such neighbor in CM database

Incorrect external neighbor • Target cell’s LAC/BCCH/BSIC in add neighbor is different from

those in equip_rtf. • Engineer modifies external neighbor at MMI, not through GUI.

Fig.27. No Handover.

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- Delay Handover

Description:

Neighbor BSIC is decoded but handover occurs in much later time. Reason:

All possible neighbors suffer blocking. Large hreqt * hreqave( the time required to take HO decision). qual_power_flag is enabled, full BTS/MS power must be reached

before handover. Large handover_recognized_period.

Fig.28. Delay Handover.

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- Ping Pong Handover Description:

Lot of handovers between cells. “Time between Handover” is around hreqt*hreqave of such HO

cause. Reason:

Improper hardware calibration. Hardware fault. UL/DL interference. Negative handover. Different coverage footprint for antennas of a cell.

Fig.29. Ping Pong Handover.

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- Negative Handover Description:

Serving cell hands over to a weaker neighbor. Reason:

ho_only_max_power is enabled. qual_margin_flag is disabled. ho_margin_usage_flag is enabled with negative

ho_margin_rxqual/rxlev. Negative HO_MARGIN. Micro-cellular algorithms are enabled, especially type 5.

Fig.30. Negative Handover.

-66dBm after HO

-59dBm before

HO

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- Over Shooting Description:

Cell shoots at far distance but that location has closer cells around. Reason:

Overshooting cell has small downtilt, 0 degree! Overshooting cell has too high altitude. Closer cells have overshooting as well. BSIC of closer cells can’t be decoded.

Fig.31. Over shooting cell.

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- High Overlapping Description:

Cells have major RxLev difference within ±5dB. Reason:

Overshooting. Too many cells in that area. Poor antenna downtilt.

Fig.32. High overlapping.

- Unreasonable Serving Area

Description:

Coverage area of the cell is incoherent to the antenna direction. Reason:

Wrong cable connection to antennas. Incorrect record of antenna orientation. Incorrect ANTENNA_SELECT.

Fig.33. Unreasonable Serving Area.

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- No Dominant Server Description:

RxLev of best neighbors are close to that of serving cell. Reason:

Poor antenna downtilt. Lack of near-by site.

Fig.34. No Dominant Server.

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- Poor Coverage

Description: Low RxLev with RxQual. In rural area, RxLev is less than 15 (-95dBm).

RxLev = 15 – 110 = - 95dBm In city center, RxLev is less than 35 (-85dBm). Different location has different threshold, noise level is the key point.

Reason: Lack of cell site. BSIC of dominant server can’t be decoded. Dominant server has blocking or cell-bar. Handover problem. E.g. missing & incorrect neighbor, negative

handover, no & delay handover.

Fig.35. Poor coverage.

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- Interference Description:

High RxLev with RxQual. Reason:

Channel interference. Not using dominant server. No handover. Turn the corner with delay handover.

Fig.36: The interference.

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-Handover Failure Description:

MS fails to reach target cell, so return to source cell. MS sends HO FAILURE and UL-SABM to source cell and there is a

response. Reason:

Channel interference. Poor coverage. External interference at UL, like wideband repeater.

Fig.37: Handover Failure.

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- Handover Loss Description:

MS fails to reach target cell, but can’t return to source cell. MS sends HO FAILURE and UL-SABM to source cell but no

response. Reason:

Channel interference. Poor coverage. External interference at UL, like wideband repeater.

Fig.38: Handover Loss.

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- UL Drop Description:

BSS doesn’t receive UL SACCH for link_fail times. BSS stops transmitting DL power.

Reason: External interference. Channel interference. Faulty ancillary. UL path loss >>> DL path loss.

Fig.39: UL drop.

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- Drop Call

Description:

DL case: Radio_link_timeout counter decreases to 0 UL case: link_fail counter decreases to 0 Layer 2: BSS/MS send SABM/DISC in every T200 for N200+1 times, and no

response from recipient Reason:

– All the cases.

Fig.40: Drop Call.

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- Sudden Power Drop Description:

Dedicated ARFCN has significant non-power control RxLev difference from RxLev of BCCH.

Reason: No/improper TX power calibration. Faulty ancillary. E.g. combiner, filter. Different cable lengths from BTS to antennas. Due to air combing, so antennas have different coverage footprints.

Fig.41: Sudden power drop.

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- MS Power Rapid Increase Description:

MS rapidly increases its TX power due to Optimised Power Control. UL SACCH multiframes aren’t received for link_fail -

link_about_to_fail times. Reason:

Sudden UL interference, e.g. wideband repeator, channel interference. Too much rapid power down. l_rxlev_ul_p is too small.

Fig.42: MS power sudden increase.

UL power rapid increase from 19 to

5 suddenly

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2- MARS (Motorola Analysis and Reporting System)

2.1- Introduction:

The Motorola Analysis and Reporting System (MARS) is a tool for the exploration, reporting and analysis of performance management statistics from a Motorola GSM network, and has the ability to store long term statistics, limited only by the available disk space. MARS has a graphical user interface (GUI), which leads the user through its functions in a logical and intuitive sequence.

2.2- MARS main features

Long term statistics data storage MARS makes statistics available indefinitely, from specified networks and OMCs, for detailed selection, analysis and reporting in both tabular and graphical formats. MARS reporting can be scheduled to happen at a specific time and on a regular basis, for example daily at 1500 hours.

Tables

MARS produces tables of selected statistics, within user defined time limits, for the entities specified by the user, in chosen formats. Comprehensive facilities are provided for instant subsetting of data in tables by where ... clause setting from an interactive window. MARS provides comprehensive printing and display formatting.

Reports

MARS produces reports of selected statistics within user defined time limits for the entities specified by the user, in chosen formats. Comprehensive facilities are provided for instant subsetting of data in reports by where ... clause setting from an interactive window. MARS provides comprehensive printing and display formatting.

Graphs

MARS produces graphs of selected statistics within user defined time limits for the entities specified by the user, in chosen formats. MARS provides comprehensive printing and display formatting.

Explore

In addition to the features provided by the MARS Graph, Table and Report facilities, the Explore option provides extended data analysis and exploration facilities. It includes

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histograms, two-dimensional and three-dimensional scatter plots and advanced statistical analysis capabilities.

Templates MARS enables the user to save and retrieve previously defined templates for table, report and graph presentation.

Cell Groups Cell Groups can be created that contain cells from one or more Sites from one or more BSCs. Saved Cell Groups are available for future selection and analysis using the MARS reporting and analysis functions.

Fig.43. The GUI of MARS.

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User Statistics By the use of formulae, which are comprised of selected statistic types, statistical analysis can be generated from the database. User defined formula (statistics) can be saved and are then available for future selection, to be used as the basis of analysis using the Table, Report, Graph, and Explore functions.

Fig.44: User statistics formulas.

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4.3- Scheduling a data load

When MARS is loaded from more than one OMC, the data load for each OMC must be completed before the next OMC load starts. The scheduled data load may take significantly longer than the same load performed manually. It is recommended that users perform a scheduled data load on a representative large OMC and note the time taken. This time, with an added margin, should be allowed as the interval between scheduled data loads.

MARS Loading Data process over view

Fig.45: Loading processes of MARS data .

Fig.46: Loading processes using telnet.exe.

MARS stats

unload directory

MARS data

directory

MARS ApplicationOMC-R

stats unload

directory

OMC-R Platform MARS Platform

Read &

Write LoadData tape

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2.4-Introduction to scheduled reports The MARS Scheduled Report function produces table reports on a scheduled (unattended) basis. Report scheduling is handled by the built in facilities of the operating system in which MARS is running. In the UNIX environment it is the Cron facility and in Windows environment it is the AT facility. Each Scheduled Report is controlled by the following:

Table template, which defines the layout of the report columns. Cell group, which defines the population of the rows. Fields that define the output, date range, and frequency of report generation.

Currently only a table template may be selected and the only output available is to a user specified file in comma-separated format that is a .CSV file. The .CSV file can be used in other spreadsheet software. Once a report name and the Template and Cell Groups to be used for a report have been defined, a report can be run on a regular basis. *Introduction to making selections The MARS Main window enables selection of statistics as follows:

Cells. Time period. Summary level (Cell, Site, BSC, OMC or Network). Intervals to use.

When data has been loaded as above, the entities for which statistics are required, the time interval, and start and end times must be selected.

*Defining intervals To select the time interval at which MARS should sum statistics, click the drop down menu in the Interval field, to display and select a preset option. The interval options offered are:

On a per interval basis of 15, 30 or 60 minutes (Quarter Hour, Half-hour, or Hour).

Rolled up to: Day. Week. Month. Year. Total (over the whole time period selected).

2.5-An example of MARS report using the table This report shows the statistics of certain BSC, cells and sites as can be configured from table_D.

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3-CTP (Call Trace Product) 3.1- Introduction: It is an advanced cell optimization and diagnostics tool that uses call trace data for analysis purposes. It gets its data form BSS equipment which has the ability to trace normal subscriber calls and to store that data on the OMC.

Using the call trace database allows:

Statistical analysis of measurement report data for individual cells or arbitrary groupings of cells.

Call analysis in which measurement report data and Layer3 messages may be viewed on a call by call basis.

Filtering of call trace files by any combination of network elements, date and time range, message type, call type, BSC and MSC trace references, and SCCP reference. Filtering can also be applied to MR Distributions reports.

Generation of pre-defined CTP reports which can be run over the Call Trace database.

Exporting of tabular and graphical data to other MS Office applications.

3.2- CTP analysis

Importing the data files which comes for the OMC-R. Using call trace explorer. Using call decode. Using MR.

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Fig.47: Importing the call traces.

Fig.48: Call trace explorer.

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Fig.49: Call decode.

Fig.50: Call trace filter.

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4-Actix (Analyzer) It is a tool for post-processing cellular network data, and runs under Microsoft Windows on a PC. It can load network performance data from many different sources, including: * TEMS Logfiles. * HP Databases. * CTP / UL Files. Once the data is loaded, a variety of analysis tools provide a clear image of overall network performance for the optimizer as: * Statistics per File. * Displaying the data on Maps. * Layer 3 Databases.

Fig.51: Exporting logfile, creating a superstream and display it on the map.

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Fig.52: Display event of the logfiles on the chart.

Fig53: Statistics per file.

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Fig.54: Layer 3 databases.

Fig.55: Replaying logfiles and displaying the state form.

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5- MapInfo 5.1- Introduction It is a comprehensive desktop mapping tool that enables you to perform complex geographic analysis such as redistricting, accessing your remote data, dragging and dropping map objects into your applications, creating thematic maps that emphasize patterns in your data, and much more. 5.2- MapInfo usage You want to include a map in your presentation or report that lets you convey statistical information in a more graphic and appropriate manner. MapInfo Map provides a variety of map display, viewing and editing capabilities, including;

Opening multiple tables at once. Controlling individual layer properties like display and labeling. Creating and modifying thematic maps. Manipulating the Map window view. Finding information associated with a map layer. Controlling map projection and units.

Because MapInfo Map provides a subset of MapInfo features, using them in MapInfo map is the same as using them in MapInfo. So, Layer Control and Thematic Mapping work the same whether you are creating a map in MapInfo or in your word processor.

Fig.56: layer control & label option.

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5.4- Thematic Mapping Thematic mapping is the process of enhancing your map according to a particular theme. At the cornerstone of the theme is the data in your table. Themes represent your data with shades of color, fill patterns, symbols, or bar and pie charts. With MapInfo Professional, you create different thematic maps by assigning these colors, patterns, or symbols to map objects according to specific values in your table.

Fig.57: Creating a thematic map.

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1-Updating the network outage Every day data are received from the OMC-R which is used to do the following analysis

- Zero call test (low volume). 0 =<volume<= 3 - Lost call test (link failure). Check the call volumes for different periods (last & present week). - Missing TCH/Radio test. Compare the expected & available TCHs. - Trend analysis. Check the BSC performance (e.g. HO success, call success, drop call rate…). - Bad BSC analysis (e.g. bad performance for HO success, call success or drop call

rate…). - Bad cell generation. Sometimes the overall performance of the BSC is good but there is a cell which performing badly thus this technique is used. It is equal to Assignment TCH * drop call. - Report for bad cell. The optimization team tries to get this information from users. - Abnormal behavior analysis (e.g. Drop call, HO failure,….). - CSSR (call setup success rate) analysis. CSSR = Call volume / Assignments. This update is done thought the following figures:

Fig.58: The data from OMC-R.

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Fig.59: Importing the text data to Access.

Fig.60: Daily alarm database in access.

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Fig.61: The BTS alarm table.

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2- Check the lost TCHs This process can be done following the next steps:

1- Get the number of SDCCH time slots from table_A also get the GPRS time slots number from table_B (tables come periodically from the OMC-R.

2- Those columns should be added to another table_C(which also comes periodically from the OMC-R

3- In table_C the SD, GPRS, TCH time and total number of time slots are counted then the expected TCH are counted (expec tch = total ts - sd ts – gprs ts - 1).

4- Then the lost TCH are found by comparing the expected TCHs from above table & available TCH from daily as in table missing ts cell and comments.

5- There is a Microsoft access that compare those TCH and run comments as follows: • Less 4 TCHs missing as a GPRS issue. • More 4 TCHs missing as a radio issue. • More 10 TCHs missing as what happened?

Note: less than 4 are chosen because of GPRS reserved & switched time slots.

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1-Statistic usages 1.1- Quality of service monitoring Quality of service is determined by statistics related to service accessibility, integrity, and retainability. - Service accessibility Statistics associated with the following processes are used to determine service accessibility: * Mobile registration & paging. Cells are grouped in location areas, and a mobile station (MS) is typically paged only in the cells of one location area when an incoming call arrives. Therefore, the MS must inform the MSC of the location area in which the subscriber should be paged. It does so by a location updating procedure. The best outcome of the procedure is when the network indicates normal service is available. Several outcomes are possible when the registration is not successful, either due to the procedure running correctly and the network providing a meaningful answer, possibly denying service or the procedure running incorrectly and the network providing an answer that is meaningless. If the MS satisfactorily updates its location, it can then be paged by the MSC when an incoming call arrives. The MSC provides the concerned BSC with the ID of the MS to be paged and the list of cells in which the paging should be issued. The BSC is in charge of managing the grouping and scheduling of paging messages and initial assignment of messages. * Network accessibility. A registered MS should be able to access the network. Access denial is divided into three main categories: 1- Call blocking.

- No signaling channel (SDCCH) is available. - No Traffic Channel (TCH) is available.

2- Failure to maintain a signaling channel or traffic channel. - Mobile is moving out of range. - Mobile is being switched off. - A hardware failure (MS or BSS).

3- Refusal by the MSC for network access. Failure to gain access to the network is pegged in BSS statistics, but for a more detailed picture MSC statistics would have to be investigated, as it is an MSC process. * Call set up time. Call set-up time is affected by post-selection delay and answer signal delay.

- Post-selection delay. Post-selection delay is the time from dialing the last digit on the fixed network, or pressing the .send. button on a MS, to receiving the appropriate tone. One possible reason for this delay is that all resources have been allocated to other calls, which may result in a queuing delay.

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- Answer signal delay. Answer signal delay is the time taken in connecting the called terminal through to the calling terminal, once the called terminal has gone off hook. The raw statistics TCH_DELAY and CALLS_QUEUED are associated with call set-up time and answer signal delay. * Call release time. Call release time is the time taken to release the call from the moment the end button is pressed (or after the handset is replaced on the fixed network). * Call release delay. Call release delay is the time between releasing one call and being able to originate another. The only aspect of concern to the BSS is queuing. All other areas are transparent to the BSS.

- Service integrity Statistics associated with the following processes are used to determine service integrity: * Call clarity. Call clarity is measured by the uplink/downlink path loss difference on the air interface. The raw statistic PATH_BALANCE is the only measurement associated with call clarity. * Lack of interference. The lack of interference is measured by the bit error rate and the interference level on monitored idle channels. The raw statistics BER and INTF_ON_IDLE are the only measurements associated with lack of interference. * Correct tones and announcements. Subscriber perceptions of service integrity are influenced by the delivery of correct tones and announcements when using the system. No statistics are available to measure correct tones and announcements.

- Service retainability Service retainability is determined by the lack of premature releases. A premature release may be affected by one of the following factors: *The base ceases to detect the RF signaling from the mobile. *The MS fails to reach the target channel on handover. * The call releases due to equipment failure (MSC, base site, or MS). * The call is lost due to emergency call preemption. A subscriber perceives a premature release as a dropped call.

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1.2- Fault finding GSM statistics can be used to find certain classes of faults in the cellular system. A set of statistics which may be used to perform this function is identified in this section.

Monitoring Faults Hard failures are normally identified via alarm surveillance. However, it is possible for a system component to deteriorate over time, while still continuing to function. The deterioration may manifest itself in a number of ways such as an increase in dropped call rate, or a lower call completion rate. Monitoring of these system parameters over time can provide the operator with an early indication of performance degradation due to deterioration in hardware components. Types of faults Examples of the types of faults that may be identified using statistics include: * Damaged antennas. * Frequency drift. * Electromechanical problems. - Problems with remote combiners. - Noisy channels. 1.3- Optimization Optimization of system parameters is necessary to ensure that the installed cellular infrastructure is utilized as efficiently as possible. Statistics can be used to monitor and verify the effects of optimization activities. For example, if handover thresholds are adjusted, statistics may be used to verify that the new threshold results in an improved handover success rate. Optimization of a GSM network is a process whereby several BSS database parameters are fine-tuned from their default values and antenna installations are adjusted to improve call success rate and quality. By optimizing a network, the performance of the cellular equipment is verified and a benchmark obtained for the system that may be used for subsequent expansion. The results may also be used to modify the original data used in the frequency planning tool. 1.4- Network planning It is possible to determine whether or not the network is correctly dimensioned for the offered traffic load. Statistics that monitor resource utilization and congestion can be used to determine when the network needs to be expanded, (or contracted, if resources are being under utilized). 1.5- Installation and commissioning Installation and commissioning of cellular equipment is a complex procedure that must be verified after completion. Part of the verification procedure uses statistics to ensure that the system is operational. Drive testing is currently one of the means used to verify installation of the network. Statistics can be used to verify the data collected during drive testing, in order to ensure that all components of the system are operational.

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2- Statistics types There are different types of statistics such as: 2.1-Raw statistics The BSS generates raw statistics for reporting individual network performance. The OMC-R processes raw statistics to create key, network health and custom statistics. These statistics include call processing, interface, and processor utilization measurements. *Call statistics: Call processing functions and features generate statistics that show how the system is performing.

*Interface statistics: Terrestrial interface activities generate interface statistics that show the activity on and condition of the interface links. The interface links are the physical connections between the MS, BSS, and MSC network elements.

*Processor utilization statistics: Processor utilization statistics show the percentage of GPROC utilization. 2.2- Key statistics Key statistics are generated at the OMC-R by processing raw statistics generated by the BSS, using predefined algorithms. These statistics are designed to give an overall indication of the condition of the system and allow comparisons of similar time period over a span of time, to help detect congestion trends and possible performance degradation. Key statistics are also provided to facilitate the monitoring of the most important network parameters. For example, various handover failure statistics may be combined and averaged over the total number of calls, to produce a handover failure rate key statistic. The following are the key statistics groupings: * Call Summary. * Channel Usage. * Connection Establishment. * RF Loss Summary. * MTL Utilization. Network health statistics Network health statistics are calculated at the OMC-R using a combination of raw and key statistics. These statistics are used to create BSS network performance reports. These reports provide an indication of the networks health from the subscribers perspective. The following are the network health report groupings: *Health check. *GPRS performance. *Handover performance. *TCH congestion. *SDCCH congestion. *Paging performance. *Radio performance.

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3- Examples of key statistics 3.1- CALL_SETUP_SUCCESS_RATE Description The CALL_SETUP_SUCCESS_RATE statistic tracks the percentage of call attempts that result in a successful TCH access. Network accesses which do not require a TCH are excluded; for example, location updates, SMS, and Supplementary Service attempts. Formula

In the above formula the numerator is the call volume which is equal to the TOTAL_CALLS statistic, this tracks the total number of calls originated for each cell on the BSS plus ASSIGNMENT_REDIRECTION statistic. This tracks the number of times a call assignment is redirected to another cell. The denominator contains the setup request count.

3.2- HANDOVER_FAILURE_RATE Description The HANDOVER_FAILURE_RATE statistic tracks the percentage of handovers that were attempted from the source cell (the cell for which the statistic is presented) that failed to successfully reach the target cell and failed to successfully recover to the source cell, that is, the handover failed and the call dropped. A handover attempt is counted when a handover command is sent to the MS. Congestion on the target cell does not result in the BSS sending a handover command to the mobile therefore this measurement is not impacted by target cell congestion.

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Formula

In the above formula the numerator contains all call lost during handovers and the denominator contains all handover attempts for the call. 3.4- HANDOVER_SUCCESS_RATE Description The HANDOVER_SUCCESS_RATE statistic tracks the percentage of handovers that were attempted from the source cell (cell for which the statistic is presented) that successfully reached the target cell. A handover attempt is counted when a handover command is sent to the MS. This key statistic includes inter-BSS Handovers. Congestion on the target cell does not result in the BSS sending a handover command to the mobile therefore this measurement is not impacted by target cell congestion. Formula

This formula is representing the percentage of the successful handovers for both out_inter and out_intra BSS plus the handover success in the intra_cell over the handover attempts.

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3.5- SDCCH_BLOCKING_RATE Description The SDCCH_BLOCKING_RATE statistic tracks the percentage of attempts to allocate an SDCCH that were blocked due to no available SDCCH resources. This statistic includes incoming SDCCH handover attempts. Formula

The above formula the numerator is equals to the ALLOC_TCH_FAIL statistic, which tracks the number of unsuccessful allocations of a TCH within a cell for both call origination and hand in. the denominator is equal to the numerator subtracted from the CHAN_REQ_MS_FAIL, which represent the number of times that the BSS times out waiting for the MS to establish on the SDCCH that was assigned to it during the immediate assignment procedure. 3.6- SDCCH_RF_LOSS_RATE Description The SDCCH_RF_LOSS_RATE statistic compares the total number of RF losses (while using an SDCCH), as a percentage of the total number of call attempts for SDCCH channels. T his statistic is intended to give an indication of how good the cell/system is at preserving calls. Formula

This formula is derived by the division of the RF_LOSSES_SD statistic that tracks the number of calls lost while using a SDCCH over the subtraction of the ALLOC_SDCCH statistic which is the sum of the number of times a SDCCH is successfully seized and CHAN_REQ_MS_FAIL which represent the number of times that the BSS times out

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waiting for the MS to establish on the SDCCH that was assigned to it during the immediate assignment procedure. 3.7- TCH_BLOCKING_RATE Description The TCH_BLOCKING_RATE statistic provides the percentage of all requests for TCH resources which fail due to no available TCH resources. Formula

The above formula is equals to the subtraction of the ALLOC_TCH_FAIL statistic ,which tracks the number of unsuccessful allocations of a TCH within a cell for both call origination and hand in, form the TCH_Q_REMOVED statistic ,that tracks when a queued call is assigned to a Traffic Channel (TCH). Over the ALLOC_TCH statistic which tracks the number of successful TCH allocations within a cell for both call originations and hand in.

3.8- TCH_RF_LOSS_RATE Description The TCH_RF_LOSS_RATE statistic tracks the percentage of TCH resources that are abnormally released due to a failure on the radio interface. Formula

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In the three previous formulas the change is in the denominator according to level which the rate of the TCH_RF_LOSS is considered. 3.9- SDCCH _BLOCKING_RATE Description The SDCCH_BLOCKING_RATE statistic tracks the percentage of attempts to allocate an SDCCH that were blocked due to no available SDCCH resources. This statistic includes incoming SDCCH handover attempts. Formulas

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Suggested RF configurations Overview of:

1- Configuration diagrams

The following series of RF configuration diagrams show suggested ways of connecting together Horizonmacro SURF and Tx blocks to meet different operational requirements. The series of diagrams is by no means exhaustive, and numerous alternative configurations may be adopted to achieve the same aim. Each Horizonmacro cabinet is represented by a SURF module and three Tx blocks. Interconnecting cables are identified by a label; N01, 2, 3 or 4. Antenna connecting cables, not supplied as part of the Horizonmacro equipment, are shown as dotted lines.

2- Depopulated site configurations

The purpose of a depopulated site configuration is to allow customers to provide a future expansion capability, at the time of installation. The diagram showing the final target configuration is to be used to connect Tx blocks, SURF and antennas. Depopulated site configurations are supplied with fully equipped RF section to achieve the target configuration, with CTUs only fitted to alternate slots. CTUs are fitted in slots 0, 2 and 4. Unused Tx block SMA connectors must be fitted with 50 ohm terminating loads.

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• SURF Module

• Single Unified Receiver Front-end. • MCell equivalent: IADU+3xDLNBs. • Six antenna connections (3 sectors, diversity receive). • Two extension ports. • Extension ports permanently connected to Rx0A and Rx0B.

Fig.62: SURF module.

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• DCF Block

• Duplexed Combining Filter. • MCell equivalent: CBF+Duplexer. • Combines two transmit outputs and duplexes with one receive input. • Most flexible block for 1-4 radio sectors. • Transmit loss approx. 4.5dB.

Fig.63: DCF block.

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• DDF Block

• Dual-stage Duplexed Filter. • MCell equivalent: 3-input CBF+Duplexer. • Combines three transmit outputs and duplexes one receive input. • Most flexible block for 3-8 radio sectors. • Transmit loss approx. 7.5dB.

Fig.63: DDF block.

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• HCU Block

• Hybrid Combiner Unit. • MCell equivalent: 900 Hybrid. • Combines two transmit outputs. • Must be used with DDF block. • Transmit loss approx. 3dB.

Fig.64: HCU block.

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• TDF Block

• Twin Duplexed Filter. • MCell equivalent: TBF+2xDuplexer. • Two completely separate transmit/receive paths. • Permits very low loss single-radio sectors to be configured. • Transmit loss approx. 1.5dB.

Fig.65: TDF block.

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Configuration for omni 1

The figure blow shows a suggested configuration, using one Horizonmacro cabinet, for omni 1 with twin duplexed filter.

Fig.66: Single cabinet omni 1 with TDF.

Configuration for omni 1 or 2(with and without diversity) The following figure shows suggested single Horizonmacro cabinet configurations, with and without diversity, for omni 1 or omni 2 with duplexed combining bandpass filter. NOTE If a single antenna (non-diversity) is required, the duplex antenna RF receive cable from the transmit block must be connected to the RxA path at the SURF. Simply switching off diversity at the OMC-R without the correct SURF configuration will cause a loss of reception.

Fig.67: single cabinet omni 1 or omni2 with DCF.

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Configuration for omni 3 or 4 The figure below shows a suggested configuration, using a single Horizonmacro cabinet, for omni 3 or omni 4 with duplexed combining bandpass filter.

Fig.68: single cabinet with omni 3 or 4with DCF.

Configuration for omni 3

The following figure shows a suggested configuration, using one Horizonmacro cabinet, for omni 3 with dual stage duplexed combining filter.

Fig.69: single cabinet omni 3 with DDF.

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Configuration for omni 4 The figure below shows a suggested configuration, using a single Horizonmacro cabinet, for omni 4 with dual stage duplexed combining filter and hybrid combining unit.

Fig.70: single cabinet omni 4 with DDF and HCU.

Configuration for omni 5 or 6 The following figure shows a suggested configuration, using one Horizonmacro cabinet, for omni 5 or 6 with dual stage duplexed combining filter and air combining.

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Fig.71: single cabinet omni 5 or 6 with DDF.

Configuration for sector 1/1 or 2/2

The figure below shows a suggested configuration, using a single Horizonmacro cabinet, for sector 1/1 or 2/2 with duplexed combining bandpass filter.

Fig.72: single cabinet sector 1/1 or 2/2 with DCF.

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Configuration for sector 1/1 The following figure shows a suggested configuration, using one Horizonmacro cabinet, for sector 1/1 with twin duplexed filter.

Fig.73: single cabinet sector 1/1 with TDF.

Configuration for single cabinet sector 3/3 The figure below shows a suggested configuration, using one Horizonmacro cabinet, for sector 3/3 with dual stage duplexed combining filter.

Fig.74: single cabinet sector 3/3 with DDF.

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Configuration for 2 cabinet sector 3/3 The following figure shows a suggested configuration, using two Horizonmacro cabinets, for sector 3/3 with dual stage duplexed combining filter.

Fig.75: two cabinet sector 3/3 with DDF.

Configuration for 2 cabinet sector 4/4 The figure below shows a suggested configuration, using two Horizonmacro cabinets, for sector 4/4 with dual stage duplexed combining filter and hybrid combining unit.

Fig.76: Two cabinet sector 4/4 with DDF and HCU.

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Configuration for 2 cabinet sector 5/5 or 6/6

The following figure shows a suggested configuration, using two Horizonmacro cabinets, for sector 5/5 or 6/6 with dual stage duplexed combining filter and air combining.

Fig.77: Two cabinet sector 5/5 or 6/6 with DDF and air combining.

Configuration for single cabinet sector 1/1/1, 1/1/2, 1/2/2 or 2/2/2

The figure below shows a suggested configuration, using a single Horizonmacro cabinet, for sector 1/1/1, 1/1/2, 1/2/2 or 2/2/2 with duplexed combining bandpass filter.

Fig.78: single cabinet sector 1/1/1, 1/1/2, 1/2/2 or 2/2/2 with DCF.

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Configuration for 2 cabinet sector 2/2/2 The following figure shows a suggested configuration, using two Horizonmacro cabinets, for sector 2/2/2 with duplexed combining bandpass filter.

Fig.79: two cabinet sector 2/2/2 with DCF.

Configuration for 2 cabinet sector 3/3/3 or 4/4/4 The figure below shows a suggested configuration, using two Horizonmacro cabinets, for sector 3/3/3 or sector 4/4/4 with duplexed combining bandpass filter and air combining.

Fig.80: two cabinet sector 3/3/3 or sector 4/4/4 with DCF and air combining.

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Configuration for 2 cabinet sector 4/4/4 Figure shows a suggested configuration, using two Horizonmacro cabinets, for sector 4/4/4 with dual stage duplexed combining filter and hybrid combining unit.

Fig.81: Two cabinet sector 4/4/4 with DDF and HCU.

Configuration for 3 cabinet sector 4/4/4 The figure shows a suggested configuration, using three Horizonmacro cabinets, for sector 4/4/4 with dual stage duplexed combining filter and hybrid combining unit.

Fig.82: three cabinet sector 4/4/4 with DDF and HCU.

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Configuration for sector 5/5/5 or 6/6/6 The following figure shows a suggested configuration, using three Horizonmacro cabinets, for sector 5/5/5 or sector 6/6/6 with dual stage duplexed combining filter and air combining.

Fig.83: Sector 5/5/5 or sector 6/6/6 with DDF and air combining.

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Field Experience Visiting different sites where: 1. The cabinet which support GSM using CTU I (OMAN). 2. The cabinet which support both GSM & EDGE both 3. CTU I & CTU II (KUWAIT). 4. Changing the tilt which is used to:

Control coverage. Reduce Interference.

There is two methods for tilting: Mechanical. Electrical.

& and changing the orientation of the antenna for Optimization. As can be seen from the following figures.

Fig.84: Downtilting the antenna.

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Fig.85: The Handheld Controller used for tilting.

Fig.86: The coverage without tilting.

Fig.87: The coverage with downtilting.

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Fig.88: No downtilte & equal path links in feed network.

Fig.89: No downtilte & unequal path links in feed network.

5. Re-location of a new site since the old site was on a small height & a new

construction caused antenna/coverage blocking. 6. Site integration where Each radios were tested for Tx / Rx performance

individually & the neighbors using TEMS. As can be seen from the table_E.

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Chapter 7:

Tables

1- Table A. 2- Table B. 3- Table C. 4- Table D. 5- Table E. 6- Missing ts & comments.

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Conclusion: Finally it was a great pleasure to attend this course over here in MOTOROLA Company since I have learned a lot in both theory & practical fields. Besides I have gain a great experience that will support my future carrier & I am looking forwarded to join this great company. Further more I hope the report will be clear an interesting.

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END

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