o046 - umts pre-launch optimisation_26 & 27 march_ncell
TRANSCRIPT
1 © 2012 AIRCOM International Ltd
O046 - UMTS Pre-Launch Optimisation
2 © 2014 AIRCOM International Ltd
Session Objectives
• The objective of this two days course is to provide the delegates with knowledge of optimisation techniques which will enable them to plan and optimise UMTS network.
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Agenda of TrainingCourse Content(Pre-Optimization)
• Optimization Overview• WCDMA Power Budget• Pilot Pollution and Power Setting of common channels• Factors Limiting Capacity• Handover Concepts• Scrambling Code Planning• Assessing a Plan
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UMTS Evolution
BSC
PSTN MSC HLR, etc
GSM Architecture
Circuit Switched
BTS
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UMTS Evolution
BSC
Serving GPRS Support Node
Gateway GPRS Support Node
Internet
PSTN
PSDN
MSC HLR, etc
Adding GPRS
Packet Switched
BTS
Frame Relay
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UMTS Evolution
BSC
Serving GPRS Support Node
Gateway GPRS Support Node
Internet
PSTN
PSDN
MSC HLR, etc
RNC
BTS
Node B
Adding UMTS
ATM
So it’s just a new modem then
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UMTS Evolution
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Major Interfaces in UMTS There are four major new
interfaces defined in UMTS
Iu
The interface between UTRAN and the CN
Iur
The Interface between different RNCs
Iub
The interface between the Node B and the RNC
Uu
The air interface
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
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Iu - the Core Network to UTRAN Interface There are two parts to the Iu interface
Iu-ps connecting UTRAN to the PS Domain of the CN Iu-cs connecting UTRAN to the CS Domain of the CN
No radio resource signalling travels over this interface The Iu interface divides the UMTS network into the radio specific
UTRAN and the CN responsible for switching routing and service provision
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
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Iur - the Inter-RNC Interface
The Iur interface allows soft handovers between Node-Bs attached to different RNCs
It is an open interface to allow the use of RNCs from different manufacturers
Its functions may be summarised: Support of basic inter-RNC mobility Support of Dedicated and Common Channel Traffic Support of Global Resource Management
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
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Iub - the RNC to Node-B Interface The Iub is an open interface to allow the support of different
manufacturers supplying RNCs and Node-Bs Its major functions are:
Carries dedicated and common channel traffic between the RNC and the Node-B
Supports the control of the Node-B by the RNC
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
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Uu - the Air Interface
Clearly the Uu must be standardised to allow multiple UE vendors to be supported by a network
The major functions of the Uu are to: Carry dedicated and common channel traffic across the air interface Provide signaling and control traffic to the mobile from the RNC and
the Node-B
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
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UMTS Compared to GSM
UMTS GSM Carrier Spacing 5MHz 200kHz
Frequency Reuse Factor
1 1-18
Power Control Frequency
1500Hz 2Hz or lower )
Quality Control Radio Resource Management
algorithms
Frequency Planning and Network Optimisation
Frequency Diversity 5MHz bandwidth gives multipath diversity with
rake reciever
Frequency Hopping
Packet Data Load Based Packet Scheduling
Time Slot based Scheduling with GPRS
Transmit Diversity Supported to improve downlink capacity
Not supported by standard but may be
applied
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GSM 9.6Kbps 9.6KbpsGPRS 40Kbps 171KbpsEDGE 120Kbps 473KbpsR99 384Kbps 2.0MbpsR5(HSDPA) 7.2Mbps 14.4Mbps
Peak data rate(Typical Deployment)
Peak data rate(Theoretical Maximum)
UMTS Evolution
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UMTS Evolution
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What is Optimisation ?
• Should involve major improvements plan for the network.
• Fine tuning of Radio Interface and Network Parameters.
• Key issues
• Coverage• Capacity• Interference• Functionality(Qos)
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Pre-launch Optimisation
• Plan (using a planning tool)
• Assess and Improve (“optimise the plan”)
• Build
• Test
• Diagnose Problems
• Rectify
Pre-launch optimization phase
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Post-launch Optimisation
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Network Dimensioning and Planning
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WCDMA Power Control
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WCDMA Power Control
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WCDMA Power Control
Example:PtxCPICH=33dBm (Parameter per Node-B)
DL RSCP = -80dBm (Measured by UE)UL_IF = –80 dBm(RTWP is received Total Wideband Power(uplink interference)
measured by RBS)UL_Required_SIR = -25 dB (Parameter per Node-B)
UE PRACH First Preamble Power = 33 dBm – (-80 dBm) + (-80 dBm) + (-25 dB) = 8 dBm
3GPP TS 25.331 8.5.7)
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WCDMA Power Control
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Random Access Procedure
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Random Access Procedure
• UE transmits the first preamble with the power determined by UL open loop PC• If the UE does not detect any acquisition indicator in AICH, it increases the
preamble Tx power by a specified offset Po
• If the UE detects the positive indicator in AICH, it transmits the random access message, 3 or 4 access slots after the UL access slot of the last transmitted preamble
• The Tx power of the control part of random access message should be Pp-m higher than the last transmitted preamble power
• The required power offset values for random access procedure PowerOffsetLastPreamblePRACHmessage in PRACH(Pp-m)
PowerRampStepPRACHpreamble (Power Ramp Step)(Po)
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Random Access Procedure
• The power ramp-up process will continue until
1) A positive AI is received from the network Send RACH message
2) A negative AI is received from the network Exit RACH procedure
3) RACH_preamble_retrans value is exhausted
4) TX power exceed UEtxPowerMaxPRACH value by > 6dB Exit RACH procedure
• When the RACH_preamble_retrans value is exhausted, PRACH preamble power will be re-set to the initial value of the cycle and a new power ramp-up cycle initiated. The preamble power ramp-up cycle will be repeated RACH_tx_Max times. At this stage the UE will send a RACH failure message to the network.
• The maximum allowed UE transmit power for the PRACH procedure is defined by UEtxPowerMaxPRACH. Layer 1 of the UE controls the UE transmit power during the PRACH procedure using the ‘commanded transmit power’. If the commanded transmit power exceeds the maximum allowed transmit power then the UE transmits the maximum allowed transmit power.
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BS RNC
UL Outer Loop Power Control
• Outer PC loop is performed to adjust the TARGET SIR in BS/UE, according to the needs of individual radio link. Required SIR depends on
• UE speed• Changes in the propagation conditions• Available multipath diversity• UE power control dynamics• SHO branches (Macro Diversity Combining)
• SIR is constantly adjusted in order to maintain a constant QUALITY, usually defined as a certain BLER target of the transport channel
• BLER is measured for each transport channel separately
DL Outer LoopPower Control
Outer Loop Power Control
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Uplink OLPC
UL OuterLoop PC
Entity #N
UL OuterLoop PC
Entity #1
UL Outer Loop PCController
RNC
BTS 1
UL Fast Closed
Loop PC
BTS 2
UL Fast Closed
Loop PC
UL Outer Loop PC In the RNC the functionality of the UL
outer loop PC is divided into two parts:
Þ UL outer loop PC Controller, one for each RRC connection
Þ UL outer loop PC Entities, one for each transport channel multiplexed in the same radio link
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Uplink OLPC Entities
There is one UL outer loop PC Entity for each transport channel in the RNC.
This UL OLPC Entity calculates the required change in SIR Target according to UL quality estimates (CRC).
One of UL OLPC Entities under the same radio link is selected to transmit the New SIR Target to the WCDMA BTS.
UL OuterLoop PC
Entity #N
UL OuterLoop PC
Entity #1
UL Outer Loop PCController
RNC
BTS 1
UL Fast Closed
Loop PC
BTS 2
UL Fast Closed
Loop PC
UL Outer Loop PC
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Uplink OLPC Controller An UL Outer Loop PC Controller controls all
UL OLPC Entities under the same RRC connection.
The UL OLPC Controller sets the parameters for each UL OL PC Entities at the RAB Setup/Modification.UL
OuterLoop PC
Entity #N
UL OuterLoop PC
Entity #1
UL Outer Loop PCController
RNC
BTS 1
UL Fast Closed
Loop PC
BTS 2
UL Fast Closed
Loop PC
UL Outer Loop PC
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Fast Closed Loop Power Control
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Fast Closed Loop Power Control
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Processing Gain(Gp dB)
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Processing Gain(Gp dB)
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Logical Channelscontent is organised in separate channels, e.g.
System information, paging, user data, link management
Transport Channelslogical channel information is organised on transport channel
resources before being physically transmitted
Physical Channels(UARFCN, spreading code)
FramesIub interface
Channel Mapping DL (Network Point of View)
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P-CCPCH
PCH
BCH
CTCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
LogicalChannels
TransportChannels
PhysicalChannels
DPCCH
Channel Mapping DL (Network Point of View)
HS-SCCH
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Logical Channels
Dedicated user data can be transmitted point to multiple to a group of UEs
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Common Control Channels BCH Broadcast Channel FACH Forward Access Channel PCH Paging Channel RACH Random Access
Channel
Dedicated Channels DCH Dedicated Channel DSCH Downlink Shared
Channel
Transport Channels
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Carrying the Transport Channels
Logical Channels
BCH
FACH
PCH
RACH
DCH
DSCH
Physical Channels
Primary Common Control Physical Channel (Primary CCPCH)
Secondary Common Control Physical Channel(Secondary CCPCH)
Physical Random Access Channel (PRACH)
Dedicated Physical Data Channel (DPDCH)
Dedicated Physical Control Channel (DPCCH)
Physical Downlink Shared Channel (PDSCH)
Synchronisation Channel (SCH)
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The Common Control Channels
The Broadcast Channel (BCH) is a cell-wide channel that is used to broadcast system and cell-specific information. The BCH is always transmitted over the entire cell with a low fixed bit rate.
The Paging Channel (PCH) is a cell-wide channel that is used to carry control information to a UE when the system does not know the location cell of the UE
The Forward Access Channel (FACH) is a downlink channel that is used to carry control information to a UE when the system knows the location cell of the UE. May also carry short user packets. (what is the use of FACCH in GSM)
The Random Access Channel (RACH) is an uplink control channel from the UE. May also carry short user packets..
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DCCH
DCH DPDCHDTCH
LogicalChannels
TransportChannels
PhysicalChannels
RACHCCCH PRACH
DPCCH
Channel Mapping UL (Network Point of View)
HS-DPCCH
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Power Setting for DL Common Channel
DL Common Control Channel
• DL Common control channels must be heard over the whole cell, thus their power setting is designed for “cell edge”.• The power of the common physical channels are set relative to the CPICH
Parameters Default (Relative) Default (Absolute)
PtxPrimaryCPICH 33 dBm 33 dBmPtxPrimarySCH -3 dB 30 dBmPtxSecSCH -3 dB 30 dBmPtxPrimaryCCPCH -5 dB 28 dBmPtxSCCPCH 1 (SF=64) 0 dB 33 dBmPtxSCCPCH 2 (SF=256) -5 dB 28 dBmPtxSCCPCH 3 (SF=128) -2 dB 31 dBmPtxPICH -8 dB 25 dBmPtxAICH -8 dB 25 dBm
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• By default the CPICH consumes 2 W of the Node B power (20 W )• For 40 W default is 4 W (10 %)
• CPICH power is used to derive the power requirements of the other Common Control Physical Channels (CCPCH)
Pilot Channel Power Setting
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Effects CPICH Power modification
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Secondary CCPCH
The Secondary CCPCH (Common Control Physical Channel) carries FACH and PCH transport channels.
FACH(Forward access channel) used for small amount of data used for transport of signaling message & user data No fast power control used
PCH(Paging Channel)Broadcast into the entire cell Support efficient sleep mode procedure.Used for transport of paging message.
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Pilot Pollution
• Pilot pollution is a situation in which a mobile station receives several pilot signals with strong reception levels, but none of them is dominant enough that the mobile can track it.
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Pilot Pollution Example
We can also see 5 scrambling codes, all within 5dBs of each other. This is clearly an area suffering from pilot pollution.
RSCP is –91dBm but Ec/Io is poor –10dB
How do you reduce Pilot Pollution?
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Pilot PollutionSite Name Sector ID SC Pilot Pollution Events RSCP EcNo DL Interf.
KAT718 B 146 679 -77.84 -9.58 6.42
KAT728 C 7 474 -79.81 -10.92 7.98
KAT706 A 415 371 -71.2 -10.32 7.15
KAT904 C 58 287 -81.17 -8.42 4.86
KAT766 A 454 237 -72.55 -9.17 5.37
KAT844 C 507 235 -73.16 -9.82 6.54
KAT718 A 126 228 -76.63 -10.02 7.02
KAT957 A 171 196 -70.59 -10.36 6.72
KAT713 B 374 189 -71.68 -10.02 6.57
KAT884 A 499 187 -70.26 -8.64 4.99
KAT843 C 435 184 -83.09 -10.35 6.93
KAT818 B 413 172 -64.38 -8.92 5.31
KAT769 B 473 159 -71.7 -8.9 5.18
KAT868 A 478 154 -70.62 -9.18 5.87
KAT830 C 477 150 -74.4 -10.37 7.18
KAT1098 C 271 148 -78.78 -9.39 5.92
KAT729 A 493 148 -77.07 -11.32 8.48
KAT1106 B 24 147 -71.69 -9.19 5.97
KAT874 B 53 147 -77.78 -10.56 7.49
KAT1108 A 131 145 -68.76 -9.82 6.72
KAT1106 C 35 140 -72.87 -9.47 6
KAT777 A 457 138 -71.61 -10.52 7.33
KAT834 B 392 119 -88.99 -10.47 7.41
KAT753 B 497 115 -68.99 -10.32 7.05
UMTS Pilot Pollution Events
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Factors Limiting Capacity
Link Budget-DL
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WCDMA Handover Principal and Analysis
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Handover
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• Why mobile systems need handover?
• UE mobility(Seamless connectivity)
• The mobile system is composed of cells which the coverage ability is limited.
The Purpose of Handover
• Providing the continuous service in mobile system is the basic element in QoS.
• The load balance: sharing the resource
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The Basic Concepts of Handover
• Active Set• Monitored Set• Detected set • Event reporting
Event reporting Radio Link (RL)
• Combination way: maximum ratio combination selection combination
• The soft handover gain• Soft handover, softer handover, hard handover
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Types of Handover• According to the signaling characters:
• Soft handover (softer handover)• Hard handover
• According to the properties of source cell and target cell• Intra-frequency handover• Inter-frequency handover• Inter-mode handover (FDD <-> TDD)• Inter-system handover (UMTS <-> GSM/CDMA2000)
• According to the purpose of handover• Based on Coverage• Based on Load (Optional)• Based on mobility of UE (Optional)• Based on Service (Optional)
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Characters of Different Handovers
Comparison between soft handover and hard handover:
Item Soft Handover Hard Handover
The numbers of RL in active set after handover
Several One
Interruption during handover
No Yes
The frequencies of cells
Only possible in Intra-frequency
cells
Occurs in Intra-frequency cells or Inter-frequency
cells
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Characters of Different Handovers
Comparison between soft handover and softer handover:
• During softer handover, the uplink signaling are combined in NodeB by maximum ratio combination, but during soft handover they are combined in RNC by selection combination.
• Compare to later one, the maximum ratio combination give more gain. So the performance of maximum ratio combination is better.
• Since softer handover is completed in NodeB, it does not consume a lot of transport resource of Iub.
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Softer Handover
RNC
NodeB
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Hard Handover
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Hard Handoff vs. Soft Handoff
Hard Handoff
Soft Handoff
Continuity of call quality is maintained and Dropped calls are minimized
Continuity of call quality is maintained and Dropped calls are minimized
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Three Steps of Handover
Decision
Execute
Measurement
• Measurement• Measurement control• Measurement execution and
the result processing• The measurement report• Mainly accomplished by UE
• Decision • Based on Measurement• The application and
distribution of resource• Mainly accomplished by RRM
in RNC
• Execution• The process of signaling• Support the failure drawback • Measurement control refresh
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Basic Concepts of Measurement• Measurement values of Handover
• Intra-frequency and inter-frequency: • CPICH RSCP, CPICH Ec/No, Path loss
• Inter-frequency:• CPICH RSCP, CPICH Ec/No
• Inter-system:• GSM Carrier RSSI, BSIC Identification, BSIC Reconfirmation
• Reporting methods of measurement• Periodic reporting • Event reporting
• The events of reporting• Intra-frequency events: 1A,1B,1C,1D,1E,1F• Inter-frequency events : 2D,2F,2B,2C• Inter-system events : 3A,3C• Others: 6G,6F
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Intra-frequency Measurement EventsIntra-frequency measurement events are identified with 1x :
• 1A : A primary pilot channel enters the reporting range. If active set of UE is full, UE stops reporting 1A event;
• 1B : A primary pilot channel leaves the reporting range;
• 1C : The primary pilot channel in a non active set is better than the primary pilot channel in an active set;
• 1D : The best cell changes;
• 1E : The measurement value of a primary pilot channel exceeds the absolute threshold
• 1F : The measurement value of a primary pilot channel is lower than the absolute threshold
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Inter-frequency Measurement EventsInter-frequency measurement events are identified with 2x:
• 2A : The best frequency changes
• 2B : The quality of the current cell frequency is lower than a certain threshold, but that of the non-used frequency is
higher than a certain threshold
• 2C : The estimated quality of the non-used frequency is higher than a certain threshold
• 2D : The estimated quality of the used frequency is lower than a certain threshold
• 2E : The estimated quality of the non-used frequency is lower than a certain threshold
• 2F : The estimated quality of the used frequency is higher than a certain threshold
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Inter-system Measurement Events
Inter-system measurement events are identified with 3x:
• 3A: The estimated quality value of the used UTRAN frequency is lower than a certain threshold, and that of the other system is higher than a certain threshold;
• 3B: The estimated quality value of the other system is lower than a certain threshold ;
• 3C: The estimated quality value of the other system is higher than a certain threshold ;
• 3D: The best cell in the other system changes
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Introduction of Soft Handover
• Soft Handover Features
• UE has several RLs with different cells----active set.
• The handover among different cells which are in same RLS is softer handover.
• Soft handover Combination:• Selection combination in uplink• Maximum combination in downlink
• Softer handover Combination:• Maximum combination in uplink and downlink
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Introduction of Soft Handover• Advantages
• Soft handover gain:• Multi-Cell gain: Multiple unrelated radio links can reduces the
required fading margin.• Macro Diversity Combining gain: Gain for the link demodulation
of the soft handover:
• Load balance: • Different cells receive the signal from a UE in uplink, which can
decrease the transmission power of UE. • Similarly, UE receive signal from different cells, which also can
decrease the required transmission power of base station.• Decrease the possibility of call drop caused by ping-pong handover.
• Disadvantages
• More resource needed in downlink, especially for the code resource of BE service.
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Measurement of Soft Handover • The measurement of soft/softer handover
• Measurement value: CPICH RSCP, CPICH Ec/No, Pathloss
• Process of Measurement: Layer 1 filter, Layer 2 filter
• Reporting way
• Periodic reporting • Event reporting
• Event type: 1A, 1B, 1C, 1D, 1F• Reporting rules: Trigger condition, Relative threshold (or
Absolute threshold), Hysteresis, Time_to_Trigger• Event reporting to periodic reporting
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Key Parameters To Optimize• Relative threshold
• Set 1A, 1B value separately • 1A < 1B, which makes deleting RL is more difficult, and it can avoid
ping-pong handover• Usually 1A: 3dB; • 1B: 6dB
• Time to trigger• Each event can be set separately• Usually, 1B>1A, which makes deleting RL is more difficult, and it can
avoid ping-pong handover• Usually, 1A: 320ms, 1B: 640ms
• Layer 3 filter coefficient• Only one value for all intra-frequency measurement• Sensitive to the delay of event trigger and ping-pong handover• Usually: 3
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Inter-frequency Hard Handover Measurement Values and Events
• Inter-frequency hard handover measurement values
• Measurement values:• CPICH RSCP, CPICH Ec/No
• Different handover purpose for different measurement type:• At the edge of carrier coverage: CPICH RSCP• At the center of carrier coverage: CPICH Ec/No
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Compressed Mode Initiation in Inter-frequency Hard Handover
• Conditions to initiate Compressed Mode (CM) measurement
• 2D event• Used to enable the compressed mode to perform inter-
frequency measurement.
• Conditions to stop measurement
• 2F event• Used to stop compressed mode. When used frequency
quality exceeds the threshold.
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Inter-frequency Hard Handover Decision Algorithm
The inter-frequency hard handover decision
• Coverage trigger handover• 2B event:
• the quality of current serving cell is lower than absolute threshold, but the quality in other cell is higher than another absolute threshold.
• Both cells are of different frequency
• Load triggers handover• 2C event:
• the quality of another frequency is higher than an absolute threshold
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Introduction of Inter-system Hard Handover
• Application scenarios • WCDMA FDD <- >GSM• WCDMA FDD <- >WCDMA TDD• WCDMA FDD <- >CDMA2000
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Measurement for Inter-system:Compressed Mode Initiated
• The inter-system measurement (GSM measurement)• Measurement type:
• GSM Carrier RSSI• BSIC Identification
• Measurement reporting• Event reporting
• 2D Event: initiate GSM measurement• 2F Event: stop GSM measurement
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Inter-system Hard Handover Decision Algorithm
• The inter-system hard handover decision
• Inter-system handover due to coverage issue• Event reporting:
• 3A event:• The estimated quality value of UTRAN frequency is lower than a
certain threshold, and that of the other system is higher than a certain threshold
• Periodic reporting:• Evaluation: According to periodic report GSM RSSI
measurement value and the BSIC confirming state of target cell of GSM system, and UE evaluates GSM RSSI of target cell is greater than the absolute threshold, then consider the cell.
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Key Parameters (I)• Parameters for Inter-system handover
• Inter-system measurement initiated and stopped threshold: • Considering different demands of CPICH Ec/No and CPICH RSCP
for PS domain and CS domain, the different 2D and 2F parameters are configured
• Inter-system measurement values (2D, 2F)• CPICH Ec/No• CPICH RSCP
• Configure the GSM RSSI threshold of CS domain and PS domain separately
• Using inter-system frequency quality handover threshold
• Trigger time delay, Hysteresis for each event
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Purpose of Compressed mode• Purpose:
• Measure the inter-frequency cell or inter-system cell under FDD mode
• Cause:• Since one receiver only can work in one frequency, the UE has
to stop working in current frequency if it is going to measure the signal from another frequency cell. To ensure the downlink service unaffected, the remained data should be sent in the limited time.
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Compressed Mode Sketch Map
One frame(10 ms) Transmission gap available for
inter-frequency measurements
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Realization Methods of Compressed mode• CM Methods
• Reduce SF by half• This double the data rate. But since amount of data not changed, it
halves the time in which it is sent, open up a gap.
• Puncturing• Decrease the coding redundancy
• Higher layer scheduling• Higher layer permit only some transport format to be used in CM, to
generate gap. Appropriate for variable-rate service.
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Scrambling Code
Scrambling Code are not orthogonal codes so they don’t required synchronization. UL: separates terminals(different UE’s) DL: Separates the sectors.
• In DL long SC are used. They are 2^18-1 i.e around 262143 In order to speed up the cell search procedure only we are uses 8192 codes out of 262143. 8192 further divided into 512 sets each sets consist of primary SC & secondary SC.
In UL there are 2^24 long & 2^24 short SC(length of 256 chips) uplink Scrambling code are available. UL scrambling code are Cell specific and are allocated in the time of connection establishment by the RNC ,Each RNC has its own planned range.
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Scrambling Code Planning
Scrambling Code allocation for Indoor & outdoor
• The Total Number of SC is 512 codes. They are separated in 4 groups outdoor (phase 0),outdoor(Future),indoor(phase0) & indoor(future)
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Scrambling Code Planning
• A cell must be allocated 1 of a possible 512 scrambling codes. The scrambling code is the pilot channel. The mobile uses this to synchronise to so that it can demodulate traffic channels and common control channels. It is clear that satisfactory network operation requires that a mobile receive a particular pilot channel from a clearly identifiable cell.
• If it receives the same pilot channel from two or more cells, confusion will result. The 512 codes are divided into 64 groups with 8 codes in each group. There are advantages if the number of codes per group is restricted or if the number of groups used is restricted.
• These advantages are in the form of:
• Handover time/success
• Mobile battery life
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Cell Synchronisation
• Chips synchronisation
• Acquire slot synchronisation
• Acquire frame synchronisation
• Identify the code group of the cell found in the first step
• Determine the exact primary scrambling code used by the found cell
• Measure level & quality of the found cell
Phase 1 – P-SCH
Phase 2 – S-SCH
Phase 3 – P-CPICH
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Cell Synchronisation
• Primary Synchronisation Channel (P-SCH)
• The P-SCH only uses the first 10% of a time slot
• A Primary Synchronisation Code (PSC) is transmitted the first 256 chips of a time slot. This is the case in every UMTS cell.
CP CP
2560 Chips 256 Chips
CP CP CP
Primary Synchronisation Channel (P-SCH)
Slot 0 Slot 1 Slot 14 Slot 0
10 ms Frame
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Cell Synchronisation (S-SCH)
• Secondary Synchronisation Channel (S-SCH)
• The S-SCH also uses only the first 10% of a timeslot
• Secondary Synchronisation Codes (SSC) are transmitted
• There are a total of 512 primary scrambling codes, which are grouped in 64 scrambling code families, each family holding 8 scrambling code members
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15
15
Scramblingcode group
group 00
group 01
group 02
group 03
group 05
group 04
group 62
group 63
1 1 2 8 9 10
15 8 1
016 2 7 1
5 7 16
1 1 5 16 7 3 1
416 3 1
0 5 12
14
12
10
1 2 1 15 5 5 1
216 6 1
1 2 16
11
12
1 2 3 1 8 6 5 2 5 8 4 4 6 3 7
1 2 16 6 6 1
1 5 12 1 1
512
16
11 2
1 3 4 7 4 1 5 5 3 6 2 8 7 6 8
9 11
12
15
12 9 1
313
11
14
10
16
15
14
16
9 12
10
15
13
14 9 1
415
11
11
13
12
16
10
Slot number0 1 2 3 4 5 6 7 8 9 1
011
12
13
14
SSC Allocation for S-SCH
87 © 2014 AIRCOM International Ltd
Common Pilot Channel (CPICH)
• A total of 512 primary scrambling codes exist
• 64 groups, 8 scrambling code in each group
• Used for cell selection and handovers
Group 0
Group 1Group 2
SC 0
SC 1
SC 8
SC 9
SC 16
SC 17
SC 2
SC 7
Group 0
Code 0
Code
Code 7
Group 63
Code 0
Code
Code 7
88 © 2014 AIRCOM International Ltd
Common Pilot Channel (CPICH)
89 © 2014 AIRCOM International Ltd
Effect of MHA
• Coverage Improvement Alternatives
Mast head amplifier
• Basic solution for optimized uplink performance
• Compensates feeder cable loss
90 © 2014 AIRCOM International Ltd
Effect of MHA
• Coverage Improvement Alternatives
91 © 2014 AIRCOM International Ltd
Dividing a Network into Clusters
• 3G network Optimization could be split into …..
(A)Cluster Optimization :
• Mainly concentrates on the detail network optimization for each individual
sub-cluster area.
• Cluster optimization work start when all the sites in the Sub-cluster have been
implemented and integrated into the Network.
• 10-12 cells form one cluster
92 © 2014 AIRCOM International Ltd
Dividing a Network into Clusters
(B) Area optimization :
• Takes broader approach by focusing the network
performance over the whole area.
• Will begin after a number of clusters have finished
implemented & optimised ClusterArea
93 © 2014 AIRCOM International Ltd
Optimisation of Site Clusters• Identify size and location of clusters
• Define cluster characteristics
• Coverage, interference, handover region size and location
• Neighbour list assessment
• Access, handover and call failures
• Take measurements
• Drive tests
• Ec/Io, pilot pollution, UE TX power, neighbours, call drop rate and handover stats
• Service allocation, FER/BLER, throughput, Max and Av. BER, Delay
94 © 2014 AIRCOM International Ltd
Drive Test Process
ClusterPreparation
Data AnalysisData Collection TroubleShooting
Define ClusterDefine Drive Route(major Routes-Airports,Hospitals,Corportate route,Hotspots etc)
Equipment NeededCall PatternsOSS AlarmsNetwork Stats
KPI DefinitionsType Breakdown Root Cause
95 © 2014 AIRCOM International Ltd
Dividing a Network into Clusters• Drive testing should be performed on radial and circumferential routes
• Radial routes show variationin signal quality with distancefrom base station
• Circumferential routes provide predictions for signal quality in different directions from the base station
• Typically, three routes should be defined per
cluster: consistency is vital
96 © 2014 AIRCOM International Ltd
Equipment: What do you Need to Measure?
• Handset Terminal Measurements
• RRC, Layer 3 Messages
• CPICH Ec/No & CPICH RSCP
• UMTS Active State & Neighbour Set
• UE State
• RLC Throughput
• BLER
97 © 2014 AIRCOM International Ltd
Field Measurement tool
• Scanner could be used for coverage and Scrambling code analysis(PCTL/RN/JDSU).
• Logging tools are available from many manufacturers(ASCOM/NEMO/Dingli
swissqual..etc)
98 © 2014 AIRCOM International Ltd
Dominance Verification
99 © 2014 AIRCOM International Ltd
RSCP Verification
100 © 2014 AIRCOM International Ltd
Ec/No Verification
101 © 2014 AIRCOM International Ltd
Pilot Pollution Verification-example
102 © 2014 AIRCOM International Ltd
Throughput Verification
103 © 2014 AIRCOM International Ltd
Drive Tests: Effect of Loading on Ec/Io
• Ec/Io can vary by 7 dB with loading conditions
• It is vital that conditions at the time of measuring are known (you will not get Ec/Io>-10 dB on a heavily loaded network)
• For pre-launch optimisation it is common to assume the network is quiet
• But, if someone else is doing a load test while the drive test is taking place…….
Drive test
Load test
104 © 2014 AIRCOM International Ltd
Drive Test Analysis – Call Patterns
• Enough call samples have to be made to make the measurement statistically valid
• In a 50 call sample, one dropped call will cause a change in performance of -2%
• In a 500 call sample, one dropped call will cause a change in performance of -0.2%
• Call length should be defined at the beginning
• We can use different call testing patterns for different optimisation techniques
• Short Calls (for Calls setup performance and delay)
• Long calls (for Drop call performance and SHO performance)
105 © 2014 AIRCOM International Ltd
Rake Receiver• Rake fingers delays tuned based on channel impluse response estimation
with the help of different fingers & attributes.(Code matched filter ,search finger, phase rotator ..etc.)
106 © 2014 AIRCOM International Ltd
Rake Receiver• Work on MRC(maximul ratio combining)
107 © 2014 AIRCOM International Ltd
Rake Receiver• Work on MRC(maximul ratio combining)
108 © 2014 AIRCOM International Ltd
Rake Receiver• Work on MRC(maximul ratio combining)
109 © 2014 AIRCOM International Ltd
Rake Receiver• Micro Diversity
110 © 2014 AIRCOM International Ltd
Rake Receiver• Macro Diversity in RNC
111 © 2014 AIRCOM International Ltd
Thank You
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