3g link budget v0.1

SENSITIVE TO T-MOBILE

LINK BUDGET FOR MACROCELLULAR UMTS FDD NETWORK

SCOPE

This document provides a link budget for the design of T-Mobile UK’s UMTS FDD macrocell radio network. A traditional uplink calculates the maximum path loss for different uplink bearers. The uplink values are then used to estimate the supportable bearer data rates on the downlink.

PURPOSE

This document should be used in cell planning in order to do high level cellular network design based upon cell range, or for specifying signal level thresholds in detailed cell planning. It can also be used to determine the effects of different base station configurations.

Please E-Mail the Corporate Library for further information about this document

DOCUMENT REFERENCE: T-Mobile/CDOC/OWNED BY : Peter Stevens

ISSUE: 0.1DATE : 11 May, 2002

T-MOBILE CORPORATE LIBRARY

THIS DOCUMENT WHEN PRINTED WILL BE

DEEMED AS UNCONTROLLEDPrinted from: EDMS/WEBSITE

Turning Information Into Knowledge© 2023 T-Mobile FOR CORPORATE LIBRARY USE ONLY

© 2023 T-Mobile SENSITIVE TO T-MOBILE

DOCUMENT TABLE OF CONTENTS

SCOPE.................................................................................................................1

PURPOSE.............................................................................................................1

1. INTRODUCTION.................................................................................5

1.1 OVERVIEW.....................................................................................................5

1.2 MAXIMUM PATH LOSS DEFINITIONS..............................................................5

2. UPLINK LINK BUDGET PARAMETERS...................................................8

2.1 UE MAXIMUM OUTPUT POWER.....................................................................8

2.2 UE ANTENNA GAIN.........................................................................................8

2.3 NODE B Eb/No...............................................................................................8

2.3 NODE B NOISE FIGURE..................................................................................11

2.4 INFORMATION RATE.......................................................................................12

2.5 UPLINK POWER CONTROL HEADROOM..........................................................12

2.6 BASE STATION RX LOSSES..........................................................................13

2.7 BASE STATION ANTENNA GAIN.....................................................................13

2.8 UPLINK SHO COMBINING GAIN.......................................................................14

2.9 SHO SLOW FADING MARGIN REDUCTION.......................................................14

2.10 INTERFERENCE MARGIN.............................................................15

2.11 BODY LOSS.................................................................................16

2.12 SLANT LOSS................................................................................17

3. DOWNLINK PARAMETERS..................................................................19

3.1 NODE B MAXIMUM CARRIER POWER.............................................................19

3.2 CARRIER LOADING........................................................................................19

3.3 MAXIMUM FRACTIONAL POWER FOR PACKET USER.......................................19

3.4 BASE STATION TX LOSSES.............................................................................20

3.5 DOWNLINK SLANT LOSS..........................................................................21

3.6 HIGHER FREQUENCY ADDITIONAL PATH LOSS...............................................21

3.7 UE NOISE FIGURE........................................................................................21

3.8 NON-ORTHOGONALITY...................................................................................22

3.9 OTHER TO OWN CELL CARRIER POWER RATIO...........................................23

3.10 UE DOWNLINK EB/NO..............................................................................23

3.4 DOWNLINK POWER CONTROL HEADROOM....................................................25

3.12 DOWNLINK SHO COMBINING GAIN...........................................................26

LINK BUDGET RESULTS..........................................................................27

4.1 UPLINK LINK BUDGET.....................................................................................27

4.2 MAXIMUM DOWNLINK PACKET BEARER RATE AT UPLINK LIMIT....................28

T–Mobile/CDOC/ of 31 Issue: 0.1


APPENDIX A - EB/NO DEFINITIONS AND RELATED FACTORS POWER-

CONTROL –TX-POWER-INCREASE AND POWER-CONTROL-HEADROOM........29

A.1 INTRODUCTION..............................................................................................29

A.2RECEIVED EB/NO...........................................................................................29

A.3 TRANSMITTED EB/NO..................................................................................29

A.4 POWER CONTROL TX POWER INCREASE.....................................................30

A.5 POWER CONTROL HEADROOM....................................................................30

A.6 SIMULATION RESULTS.................................................................................31

DOCUMENT HISTORY..............................................................................32

ATTACHMENTS.

List any attachments to this document here.

REFERENCES.

1. ‘Typical dimensioning parameters’, AP8 from TMO – Nokia Radio Performance Workshop, 18/06/01.

2. ‘CEM Alpha performance vs. realistic profiles’, Jules Vidal (Nortel), presentation to TMO-Nortel Radio Performance Workshop

3. ‘max.mobil. Siemens Workshop 2001-12-20’4. ‘Node B system description’, Nokia contract document agreed 2 October.5. ‘WCDMA Masthead Amplifier(MHA) Product Description’, Nokia User Manual ,

DN0114715, issue 1-0 en.6. ‘RAN system description’ Nortel contract document, 16/8/01.7. Presentation to TMO-Nokia link budget meeting, UK, 12/2/02.8. Minutes (with action response LB1) of TMO-Nokia link budget meeting, UK, 12/2/029. ‘WCDMA link performance indicators, simulator principle and and examples’ Kari

Sipila (Nokia), NET/IMN/WNP/NSR, v 0.1.0.10. ‘WCDMA link budget’, Jussi Reunanen (Nokia), 11/12/2000.11. ‘WCDMA for UMTS’, Holma & Toskala, Wiley, 2000.12. ‘Results on the peak to average power effect on coverage’, Ericsson, ETSI SMG2

UMTS-L1 490/98, Oct. 1998.13. UMTS uplink link budget’, Juan Pedro Benitez, Nortel-TMO Radio

Planning/Performance workshop, 29/11/0114. ‘Link budget for a personal communication network’,

Mo2o,/CDOC/P2.2/KNG/REPT/3253, Ken Ng, Issue 1.0, 6/9/95.15. ‘Comparison of the performance between vertically polarised and cross polar

antennas’, Brian Williams, One2one/CDOC/6032, Issue 2.0, 21 September 2000.16. ‘Cross polarised antenna results’, Wolfgang Stoermer, T-Mobil.17. ‘WCDMA radio access network RF dimensioning guidelines’, EEM/TG/N-99:0042,

8/12/99.18. ‘Power Divider Unit (WPD) description’, DN015603, DRAFT 1, Nokia.19. ‘Default power settings for common DL channels in WCDMA RAN1- 1.5’, Kari Sipila,

Nokia presentation to TMO radio performance workshop, 18/06/200120. ‘Nokia UltraSite WCDMA Antenna System Product Overview’, DN00309809.21. ETSI TS GSM 03.30.22. ‘Nokia WCDMA FDD BTS RF Performance’, Mikko Siira, 15/2/01. 23. ‘RTT Revision – Performance results’, ETSI SMG2 351/98.



1. INTRODUCTION

1.1 OVERVIEW

The limited power at the terminal restricts uplink bearer rates to be lower than those possible on the downlink. On the downlink, PA power is shared, and by allocating user a large fraction of the total carrier power it is possible to support high data rates even at the cell edge. This sharing of power makes the downlink link budget more elastic than the uplink.

It is therefore proposed to base cell planning for macrocells on uplink bearer requirements. The uplink part of the link budget calculates the maximum path loss supportable between base station and terminal, for a range of different bearer rates. The parameters associated with this uplink calculation are discussed in detail in section 2.

However, it is nevertheless important to understand the networks’ downlink capability. The path losses provided by the uplink link budget are used to estimate a supportable bearer rate on the downlink at the cell edge as defined by the uplink.

Section 1.2 discusses the maximum path loss definitions including the output of the uplink link budget.

Section 2 proposes parameters values to be used in the uplink link budget.

Section 3 proposes parameter values to be used in the downlink section of the link budget.

Section 4 provides link budget tables taken from an Excel spreadsheet.

Appendix A describes in more detail various parameter associated with Eb/No.

It should be noted that if the above approach is also utilised for mini- and micro- base stations with limited downlink power, it will imply an inconsistent level of service in different types of cell. The link budget.

1.2 MAXIMUM PATH LOSS DEFINITIONS

It is important to define clearly the result of the uplink link budget so that its application is consistent with its calculation.



The intent of this link budget is to include technology and bearer-dependent factors within the calculation, but exclude more commercial factors relating to probability of coverage and in-building penetration. The latter effects may vary form network to network, whereas the former should stay the same.

The maximum path loss (less body/slant loss) output of the link budget is therefore defined as the maximum propagation loss in the uplink band between ‘closest’ base station and terminal on boresight, as measured by placing 0 dBi vertical antennas at the locations of the base station antenna and terminal.

With this definition the body loss and slant loss do not form part of the maximum propagation loss, and therefore it is important that factors for these are part of the link budget calculation.

For the calculation of a cell range or an outdoor signal level from the maximum path loss one must reduce the maximum path loss by the building penetration loss and total shadow fading margin to calculate a required outdoor mean path loss/signal level. It is assumed that the propagation loss model does not include a slant loss factor.

Note that macro-diversity or soft handover combining gains are added within the link budget calculation as technology factors, on the assumption that in most cell edge situation there is the possibility of several cells providing service. Any shadow fading margin applied in calculating a cell range or outdoor signal level threshold should therefore assume a single serving cell.

Figure 1.2.1 - Illustration of link budget path loss terms


-Body loss-Slant loss

-Antenna gain-RX/TX losses (jumpers, etc)

-Penetration loss-Slow fading/penetrationmargins (single cell)

Maximum path loss less body/slant loss

Outdoor path loss

Maximum path loss including body/slant loss


2. UPLINK LINK BUDGET PARAMETERS

2.1 UE MAXIMUM OUTPUT POWER

Four UE categories are defined in the 3GPP Standard in TS 25.101. The required output power of the various terminal types is given in the following table:

UE category

Nominal Maximum

Output Power [dBm]

Tolerance[dB]

1 33 +1/-32 27 +1/-33 24 +1/-3 4 21 2

Table 2.1.1 : Maximum output power of various UE categories

The RFI responses from terminal manufacturers suggests that terminals with maximum output power of both 21 dBm and 24 dBm are under development. The majority are planning to provide the 21 dBm class.

It has been noticed that some manufacturers of 2G phones take advantage of the tolerance range to design phones with a lower output power than the nominal output level. However, it is not proposed to plan for a average shortfall in UE output power from the nominal value until more measurements are available.

A UE maximum output power of 21 dBm is recommended.



2.2 UE ANTENNA GAIN

There is a possibility that some data terminals will have directional antennas with positive antenna gain. However, this cannot be relied on for most terminals, and hence no antenna gain is assumed.

A UE antenna gain of 0 dBi is recommended.

2.3 NODE B Eb/No

Eb/No is a receiver performance metric given by the ratio of received energy per bit to noise density at the point which receiver is just able to decode the received signal with the required quality (typically FER). Eb/No depends on the service, the velocity of the UE, and the degree of multipath.

The node B Eb/No figures given here assume the use of diversity in the node B, with Eb defined as the energy per bit per receiver branch.

There are no measurement results available at this time, and therefore Eb/No values are derived from supplier simulation results and specification values. It is assume that fast power control is being used. The power control headroom factor is used to compensate for the fact that UE at cell edge will have a capped maximum power.

A series of TMO workshops was held with TMO’s preferred suppliers in order to obtain performance data for UMTS network design. The following tables summarise the uplink Eb/No values for pedestrian @ 3km/h and vehicular @120km/h mobiles for different bearers [1,2,3].

Bearer Service

Data Rate [kbps]

Nokia Nortel Siemens

AMR Voice 12.2 4.0 6.3 3.3Circuit 64 2.0 4.8 2.2Circuit 128 1.5 4.4 1.8Circuit 384 - 4.2 0.6Packet 64 2.0 3.2 1.4Packet 128 1.5 2.8 1.1Packet 384 1.0 2.6 0.2

Table 2.3.1: Supplier Uplink (NodeB) Eb/N0 Values [dB] for 3 km/h users

Bearer Service

Data Rate [kbps]




AMR Voice 12.2 5.0 6.4 6.1Circuit 64 - 4.9 3.8Circuit 128 - 4.4 2.9Circuit 384 - 3.9 2.7Packet 64 3.3 2.9 3.6Packet 128 3.0 2.6 2.9Packet 384 2.0 2.3 2.3

Table 2.3.2: Supplier Uplink (NodeB) Eb/N0 Values [dB] for 120 km/h users

Assumptions:

Nokia Voice 20 ms Interl., CS data 40 ms Interl., BLER 1% P-data 10 ms Interl. BLER 10%.Nortel QoS: PSdata Global RBLER 10^-1, Voice BER 10-3, CS BER 10-6 , 1 dB implementation margin

for HW/SW implementation,Siemens QoS: Voice Coded BER= 10^-3 for Voice, BER= 10^-6 for LCD, BLER=10%, Voice and CS

Convolutional Coding, PO Turbo Coding, no implementation margin

Due to the small differences in the Eb/No values for 128 kbps and 144 kbps, it is assumed that values for 128 kbps can be substituted with values for 144 kbps and vice versa.

The differences between the supplier’s figure can be explained by differences in the simulation assumptions. For instance Nortel, unlike Nokia, includes the overhead of the 3.4 kbps associated signalling radio bearer (SRB), and includes a 1 dB implementation margin.

One further source of Eb/No performance figures is the 3GPP specifications. The table below shows the uplink Eb/No performance required by 3GPP 25.104 for the 3 propagation cases for which performance results are provided.

Bearer Service

Data Rate [kbps]

Case 1 Case 2 Case 3

AMR Voice 12.2 11.9 9 7.2Circuit

(BLER=1%)64 9.2 6.4 3.8

Circuit (BLER=1%)

144 (128)

8.4 5.6 2.7

Circuit (BLER=1%)

384 8.8 6.1 3.1

Packet (BLER=10%)

64 6.2 4.3 3.4

Packet (BLER=10%)

144 (128)

5.4 3.7 2.8

Packet (BLER=10%)

384 5.8 4.1 3.2

Table 2.3.3: 3GPP Uplink (NodeB) Eb/N0 Values [dB]



The multipath propagation model cases used by 3GPP for the above are summarised in the table below. Case 1 has one dominant Rayleigh faded component. Case 2 has 3 equal power paths with very large delay spread. Case 3 has the most typical urban/suburban multipath profile, but unfortunately the results are only applicable for high speed.

Case 1, speed 3km/h Case 2, speed 3 km/h Case 3, 120 km/hRelative Delay

[ns]Average Power

[dB]Relative Delay

[ns]Average Power [dB] Relative

Delay [ns]Average

Power [dB]0 0 0 0 0 0

976 -10 976 0 260 -320000 0 521 -6

781 -9Table 2.3.4: 3GPP propagation model cases

It can be seen that the 3GPP Eb/No values are significantly higher than the values provided by the vendors, particularly for case 1 and case 2. One reason for that is that the 3GPP values are based on simulations without power control. To fairly compare them with the vendor values, the power control headroom should be subtracted in the 3km/h multipath case 1 and case 2 figure.

Most of the rest of the difference can be attributed to the suppliers ensuring a large implementation margin is included in the specification for performance commitments. With the exception of Nortel, supplier have not commited to their own recommended values.

The available sources assume a variety of quality measures for circuit switched data. It is not considered worthwhile to design to a very stringent quality requirement for circuit switched data at cell edge, as the marketing interest in the circuit switched services is not very great. Therefore we take a BLER of 1% as the cell edge design target for link budget purposes. Closer to the centre of the cell this not prevent a more stringent target being applied to power control.

To obtain TMO recommended Eb/No figures the vendor and 3GPP figures have been combined by taking a weighted mean of compensated figures. The compensations applied were as follows.

1. To 3GPP, Nokia [and Siemens] figures, overheads for supporting the SRB were added as shown in the table below, derived from the ratio between the SRB and the bearer information rate.

Bearer Service

Data Rate [kbps]

SRB overhead

[dB]



AMR Voice 12.2 1.1Circuit 64 0.2Circuit 144 (128) 0.1Circuit 384 0Packet 64 0.2Packet 144 (128) 0.1Packet 384 0Table 2.3.5: SRB overhead for different bearers

2. To the Nokia and Siemens figures a 1 dB implementation margin was added.

3. To the 3GPP figures, the power control headroom as given in table 2.2.1 was subtracted.

4. To apply the most realistic 3GPP case 3 figures to the 3km/h value , a reduction of 1.1 dB was applied to account for improved power control performance at reduced speed. This figure was obtained by averaging the difference between the supplier’s Eb/No figures for the two speeds selected.

The weightings applied for the pedestrian @ 3km/h case were as follows:

Source Weighting

Nokia 20%Nortel 20%

Siemens 20%3GPP Case 3 20%3GPP Case 1 10%3GPP Case 2 10%

Table 2.3.6: Weighting applied for calculation of uplink 3km/h Eb/No

After performing the weighted mean calculation the recommended value for uplink Eb/No are as follows:

Bearer Service

Data Rate [kbps]

3 km/h 120 km/h

AMR Voice 12.2 6.9 7.7Circuit 64 4.1 4.5Circuit 128/14

43.3 3.6

Circuit 384 3.1 3.4Packet 64 3.2 3.9Packet 128/14

42.6 3.3

Packet 384 2.4 3.0Table 2.3.7: Recommended Uplink (NodeB) Eb/N0 Values [dB]



2.3 NODE B NOISE FIGURE

The table below shows receiver noise performance for the different vendors.

Noise Figure [dB]


NodeB (w/o TMA)

31 2.22 5

NodeB (with TMA)

2.53 2.04 3

Table 2.1.1

The overall Node B noise figure can generally be reduced by the use of TMA. With a TMA, the reference point for system noise figure and hence receiver sensitivity is moved from the top of the node B cabinet to the input to the TMA.

In the case of the Nortel figures, the guaranteed BTS noise figure is similar to the guaranteed MHA noise figure, so a slight degradation is seen. However, the MHA typical noise figure is only 1.6 dB, so some further improvement in the TMA figure might be expected.

The recommended node B noise figure is dependent on the use of TMAs as shown in the following table.

Node B Noise Figure [dB]

NodeB (w/o TMA) 3.5NodeB (with

TMA)2.5

Table 2.3.1 Recommended values for node B noise figure

2.4 INFORMATION RATE

This is the bearer information rate provided by the RLC layer to the upper layers.

2.5 UPLINK POWER CONTROL HEADROOM

1 Calculated from static sensitivity and Eb/No data provided in Node B system description [4]. 2 Contract features and requirements, see annex, feature number 23470.3 Calculated using Friss’ equaltion with TMA NF of 2 dB, TMA gain of 12 dB [5], and cable loss of 3 dB.4 Calculated using Friss’ equation with TMA typical NF of 1.6 dB, TMA gain of 12 dB [6], and cable loss of 3 dB. TMA guaranteed noise figure of 2db equates to 2.4 dB system noise figure


Peter Stevens, 03/01/-1,


This component of the link budget arises because the Eb/No values used within the link budget are receiver Eb/No values which assume power control can counter the effects of Rayleigh fading. In reality at the cell edge, the transmitted power is capped by the maximum output power.

Further description of this factor can be found in appendix A.

The power control headroom is dependent upon the type of bearer (notably required BLER/quality), the speed of the UE and the amount of multipath. The values recommended below are derived from published Ericsson results for Pedestrian B (Appendix A, section A6).

Nokia apply a power control headroom (also called fast fast margin) of 3 dB for 3 km/h in their link budget [7]. This is derived from simulation results for Vehicular A [8], but the BLER is unknown. Nortel do not inlude such a parameter.

A uplink power control headroom is recommended as follows:

Power Control HeadroomTerminal Speed Circuit Packet 0 km/h 2 dB 0.9 dB120 km/h 0 0

Figure 2.2.1 Recommended values for UL power control headroom

2.6 BASE STATION RX LOSSES

This parameter needs to cover the total losses between the connector of the antenna and the point at which the noise figure is referenced.

For a Node B without TMA, the reference point is the connector on top of the Node B cabinet. The total loss is made up of the main feeder loss, the connector losses and the jumper loss. The main feeder loss is dependent upon the length and type of cable used.

Cross-section Attenuation [dB/100m]

½“ Highflex 17.0½“ (LDF450) 11.57/8“ (LDF550) 6.71 ¼“ (LDF650) 4.81 5/8“ (LDF750) 4.22 ¼“ (LDF1250) 3.8Table 2.4.1: Typical values for cable attenuation

For a Node B with TMA the reference point is the receiver input to the TMA. The total loss is made up of connector losses and jumper loss.



It is recommended that the following base station RX losses values are used.

RX losses (dB)

NodeB (w/o TMA) 2.5NodeB (with TMA) 0.5Table 2.4.2 : Recommended values for base station RX losses

2.7 BASE STATION ANTENNA GAIN

The planned antenna for 3G deployment is the Kathrein 742 212 multiband adjustable electrical downtilt cross polar antenna. This antenna provides a boresight gain of 18 dBi in the frequency range 1920-2170 MHz.

A node B antenna gain of 18 dBi is recommended.

2.8 UPLINK SHO COMBINING GAIN

The total gains arising from soft handover can be considered to be made up of two components: soft handover (SHO) combining gain and the SHO fading margin reduction.

The SHO combining gain is defined as the reduction in transmitted power in a soft handover state compared to the power required to connect to the ‘closest’ of the cells without soft handover. It is assumed that soft rather than softer handover is applied at the cell edge. Soft handover means that selection combining is done at the RNC, which is less effective than softer handover where maximum ratio combining can be performed by the node B. The uplink SHO combining gain arises from the diversity benefit in counteracting fast fading effects.

The gain depends upon the difference in path loss with the two serving base stations. Nokia simulations [8, 9, 10 (fig 9.22)] show a gain of about 1.5 dB for equal path loss, falling to 0.5 dB for a 3dB difference and then 0 dB at 6dB difference. These simulations results assume fast power control is operating.

At the cell-edge, soft handover has the further benefit of reducing the power control headroom because of the increased diversity. In Ericsson’s simulations with no power control for Pedestrian B at 3 km/h [11], the reduction in transmit power is 2.3 dB for equal path losses and 0.9dB for a 3 dB difference in path loss between the serving base stations.



Nokia, despite the simulation results described above, recommend an uplink SHO combining gain (MDC gain) of 0 dB [1,9].

Soft handover will provide some combining benefit in many cell edge situations, and therefore a small positive gain seems to be justified. In selecting a value for this parameter, a relatively cautious value is chosen since there shall always be many locations (e.g. deep in-building) with a single dominant server where the application of a large SHO gain is not appropriate.

A uplink SHO combining gain of 0.5 dB is recommended.

2.9 SHO SLOW FADING MARGIN REDUCTION

As mentioned in the previous section, the soft handover benefit can be split into two parts, an SHO combining gain and a reduction in the slow fading margin.

The slow fading here encompasses both the outdoor slow fading, the variation in penetration loss from building to building and the variation in signal within the building by local shadowing. It is assumed governed by Gaussian statistics. The slow fading margin reduction arises when there are two potential serving cells. The slow fading margin required can be reduced if only the better of two Gaussian random variables needs to exceed a given level with a certain probability, than is the case for a single variable of the same standard deviation.

This fading margin reduction can also be obtained in GSM, but is not as great for GSM because a hysteresis is generally applied which lowers the confidence of being connected to the better server.

The fading margin reduction can be calculated relatively easily for the cell-edge case when the slow fading is uncorrellated from cell to cell. For equal signals with a standard deviation of 7 dB, the gain is about 6 dB. With a difference of 3.5 dB, this drops to about 4.5 dB.

To obtain an area probability, an integration over the cell area is required. Nokia estimate the gain in the uncorrellated area integration case to be 5.1 dB.

Unfortunately, slow fading of receive signals from two cell is often correllated, and this reduces the gain. To understand this better, consider an in-building user near a cell border. If he is deep within a building, then it likely that the signals from both local cells are substantially attenuated. However if the user is situated on the opposite side of a building from one cell and therefore suffers high slow fading attenuation, it is quite probable that the other serving cell is pointing at that side of the



building so is not so strongly attenuated. The correlation in this case is less and could even be negative!

For correllated fading, Nokia use a ‘Viterbi’ method to calculate slow fading margin reduction. The gain is reduced to 3.3 dB [7]. In their link budget a figure of 2 dB is used [7].

Nortel have also provided a similar calculation of SHO slow fading margin reduction for the correllated case [13]. The results are shown in the table below.

Outdoor vehicular

Outdoor to indoor suburban

Dense urban/ur

banArea reliability 94% 94% 94%

Standard deviation (dB)

10.2 8.9 8

Shadow margin (dB) 9.9 8.1 6.9SHO slow fading

marging reduction (dB)2.9 3.5 3.1

Table 2.9.1 Nortel results for slow fading margin reduction

In selecting values for the handover gains, a cautious value is chosen since there shall always be many locations with a single dominant server where the application of a large SHO gain is not appropriate.

A SHO slow fading margin reduction of 2 dB is recommended.

2.10 INTERFERENCE MARGIN

The uplink interference margin defines the allowable uplink noise rise seen in at the base station.

The instantaneous noise rise can be related to loading (fraction of pole capacity, UL ) by the simple equation [9 eq. 9.2].

Noiserise [dB ]=10 log

11−ηUL

T–Mobile/CDOC/ of 31 Issue: 0.10.00% 20.00% 40.00% 60.00% 80.00% 100.00%0

1

2

3

4

5

6

7

8

9

10

Loading

No

ise

ris

e (

dB

)


This equaltion is plotted in figure below.

Figure 2.10.1 Classical relation between uplink loading and noise rise

A high noise rise, also known as the cell-breathing effect, is undesirable as it signifies a unstable service area. A noise rise limit of 3 dB is recommended as a long term planning assumption, which equates to 50% loading.

In the short term however, a lower noise rise limit maybe assumed in order reflect the low traffic levels expected in the early network. An initial planning load of 30%, or 1.5 dB noise rise has been proposed.

It should be noted that utilisation of such a low noise rise may limit the use of high speed uplink bearers. This is especially true for a 384 kbps bearer which is estimated to add a 33% load to cell5, exceeding the total noise rise limits.

A interference margin of 3 dB is recommended in the long term. In the short term a value of 1.5 dB may be used.

2.11 BODY LOSS

The body loss arises from the use of the UE close to the body or other objects in close proximity. In practice, it shall depend upon the type of terminal and the way it is used.

It is assumed that the speech service is carried on a handheld terminal held against the head. For the speech service, the same body loss as used by T-Mobile UK in their 2G link budget [14].

The use of a UE for data services typically means that the UE may placed some distance from the body with a resultant lower body loss. Nevertheless, the UE may still be attached to the body of the user, or suffer some additional loss from being placed on furniture. It is therefore recommended that a residual body loss is included in the link budget for data services. A 2 dB loss in this case is proposed.

The value used within the vendor link budgets are shown below. The values of 3 dB (voice) and 0 dB (data) used by most vendors seems to derive from values used in the ITU UMTS technology evaluation.

Bearer Service


5 Assumes a Eb/No of 2.9 dB, i=0.7.



Voice 3.0 3.0 3.0Data 0.0 1.0 0.0

Table 2.11.1: Supplier values for body loss.

The recommended body loss values are as given in the table below.

Bearer Service

Body Loss[dB]

Voice 5.0Data 2.0

Table 2.11.2: Recommended values for body loss.

2.12 SLANT LOSS

Current plans for 3G antenna deployment assume the use of cross polarised antennas.

The use of cross polarised antennas is expected to degrade link budget performance when compared to vertically polarised antennas.

T Mobile UK has performed measurements comparing the use of cross polar base station antennas with vertically polarised antennas in drivearound tests [15] for its 1800 MHz GSM network. The findings show that the difference in performance with vertically polarised base station antennas is very dependent upon the relative orientation of the mobile antenna, and particularly so in more open environments. When the base station and mobile antenna orientations align, a small gain of 1.9 dB was seen compared to the use of vertically polarised base station antennas. However when the mobile antenna is perpendicular to orientation of base station antenna, a loss of up to 16.6 dB was seen.

In suburban or urban areas, the dependency on the mobile antenna orientation was less marked and a loss of 1.1/0.7 was seen in the suburban/urban cases when mobile and base station antennas were aligned, and a loss of 2.4/2.6 dB seen when antennas were perpendicular.

Further evidence of a slant loss arises from traffic reductions seen in live sites whose vertically polarised antennas have been swapped for cross polarised one in capacity upgrade.

In the built-up areas, the slant can be explained by the filtering effect of reflections from vertical surfaces which tend to depress the horizontal component of the signal compared the vertical one. Transmitting on a slant therefore reduces the amount of power carried on the dominant vertically-polarised path.



T-Mobil have also made cross-polar vs. vertically polarised antenna performance measurements for GSM at 900 MHz [16]. In drivearound tests the results differ for a roof-mounted vertically polarised mobile antenna and an in-car antenna. A significant degradation is seen in the case of a roof antenna, but the degradation was not significant in the measurements done with the in-car antenna. In further measurements collected by A-bis interface logging, the average signal level appears to drop by approximately 2.5 dB with cross polar antennas.

In the table below we show the recommendations of various other suppliers with respect to their assumed slant losses.

Company Slant loss (dB)

Reference

Ericsson 1.5 [18]Nortel 1.5 [12]BT Cellnet (Chelsea)

1.5

Kathrein 2CSA 2Nokia -

Table 2.12.1 Slant loss recommendations from suppliers

A slant loss of 2 dBi is recommended.



3. DOWNLINK PARAMETERS

3.1 NODE B MAXIMUM CARRIER POWER

This is the maximum output power per carrier.

Nokia offers two types of power amplifier with output powers of 20W and 40W. In addition they offer a rollout configuration (ROC) which splits the transmittted signal over 3 antennas, also called ‘omni transmit sector receive’ (OTSR).

S111 OTSR/ROC 20W PA 43 dBm [-0, +2] 37.7 dBm6

40W PA 46 dBm [-0, +2] 40.7 dBmFigure 3.1.1 Nokia Node B output power

It is currently assumed that 40W PAs will be used to maximise cell-edge bearer rates.

A node B maximum carrier power appropriate to the Node B type deployed should be used. 46 dBm is recommended for the preferred 40W PAs.

3.2 CARRIER LOADING

This parameter defines the loading of the carrier power by all channels supported by the carrier over the period that a high bearer rate packet channel is utilised. The parameter is needed in order to calculate the level of intracell interference at the receiver.

A high loading level is selected in order to maximise the available power for the high speed packet bearers. A 10% headroom is assumed to support a variation in power through a slot. One example of such a variation is the multiplexing of the SCH1&SCH2 channels with the P-CCPCH channels. If there is a difference in power levels allocated to these groups of channels, the power is discontinuous through the slot. In the pre-optimised network, Nokia recommend [19] that SCH1&SCH2 are each allocated 5% of downlink power, and P-CCPCH is allocated 3.2%. The P-CCPCH takes up 90% of the slot. This gives a average loading of 3.4%, but rising 6.6% above this value in the first 256 chips of the slot.

A carrier loading level of 90% is recommended.

3.3 MAXIMUM FRACTIONAL POWER FOR PACKET USER6 5.3 dB splitter insertion loss [18]



This parameter indicates the maximum fraction of the maximum node B carrier power that can be allocated to one high data rate packet user.

The available power for such a user is equal to the planned carrier loading less the power required for common channels and power required for the non-controllable traffic. It is assumed that one user can use all of the power allocated to controllable NRT packet users. When there is more than one user, the fractional power per user is reduced and the bearer rate is reduced by the packet scheduler.

Nokia have made made some proposals for the powers allocated to the various downlink channels in early deployment [19]. Another source of settings for these channel powers are the 3GPP test specification 25.133 and 34.108. Nokia and 3GPP values are compared in the table below.

Common control channel

Fractional Power

Nokia value 3GPP valueCPICH 10% 10%SCH1 5% 3.2%SCH2 5% 3.2%AICH 1.6% 3.2%PICH 1.6% 3.2%P-CCPCH 3.2% 6.3%S-CCPCH (SF=64) 12.6% 6.3%Total (assuming averaged SCH & P_CCPCH)

29.2% 28.7%

Figure 3.3.1 Fraction of power used for common control channels

It is likely that the fraction of power will be reduced as a result of optimisation.

For the purposes of determining an appropriate fraction of power available for NRT high speed packet users, we assume that initially 30% of maximum carrier power is allocated to the control channels, with a likely improvement to 20% over time. Assuming the RT traffic utilises 15% of available carrier power initially, rising to 25% with the lower common channel power, this leaves 45% of power for the NRT users. This is summarised in the table below.

Initial OptimisedCommon channels 30% 20%Non-controllable RT trafffic

15% 25%

NRT traffic 45% 45%Total 90% 90%

Figure 3.3.2 Allocation of power between different types of channels

A maximum fractional power for packet user of 45% is recommended.



3.4 BASE STATION TX LOSSES

The downlink TX losses should include all losses between the node B output connector and the connector on the antenna. It should include all connector losses, feeder losses, TMA insertion losses and jumper cable losses.

The table below shows the MHA insertion losses for Nokia and Nortel.

Nokia NortelTMA insertion loss 0.3 dB 7 0.3 dB

Table 3.4.1 TMA insertion loss for Nokia and Nortel

The bias tee is housed within the Node B cabinet of both Nokia and Nortel.

Allowing for additional connector losses on the TMA , the insertion of the TMA can be expected to add about 0.5 dB to the total downlink TX losses.

It is recommended that the following base station TX losses values are used.

RX losses (dB)

NodeB (w/o TMA) 2.5NodeB (with TMA) 3Table 3.4.2 : Recommended values for base station TX losses

3.5 DOWNLINK SLANT LOSS

The same slant loss is assumed for the downlink as the uplink.

A downlink slant loss value of 2 dB is recommended.

3.6 HIGHER FREQUENCY ADDITIONAL PATH LOSS

The FDD downlink band is 190 MHz higher than the uplink. Consequently it suffers an higher path loss than the uplink.

The COST 231 Walfish-Ikegami propagation model is used to estimate the additional downlink loss [21]. For the mid-band frequencies of 1950 MHz and 2140 MHz, a difference in the intercept point of 1.6 dB was obtained.

7 Original MHA loss is 0.6 dB [20]. Nokia have recently commited to 0.3 dB for new MHA product.



A higher frequency additional path loss value of 1.6 dB is recommended.

3.7 UE NOISE FIGURE

The UE noise figure requirement is not explicitly stated in the 3GPP specification, but is implied within the senstivity requirement. The 3GPP specification requires a senstivity of –117 dBm for static conditions at BER of 10-3. This is commonly considered to be the equivalent of requiring a noise figure of 9 dB. Assuming an static Eb/No without diversity of 6.5 dB [22] and non-orthogonality of 0 for a static channel, the –117 dBm requirement can calculated as equivalent to a noise figure of 9.6 dB. The small difference between 9 and 9.6 can be considered as signal processing implementation margin. GSM terminal performance is also a useful point of comparison. The receive sensitivity of –102 dBm is equivalent to a noise figure of 9.7 dB8.

Selecting a noise figure based upon the worst case performance in the standard is considered slightly too pessimistic for the typical terminal. 1 dB is subtracted from the 9 dB value to give a typical UE noise figure of 8 dB.

The values recommended by the suppliers are given in the table below.

Nokia Nortel

UE noise figure

8 9

Table 3.7.1 Supplier recommendations for UE noise figure

A UE noise figure value of 8 dB is recommended.

3.8 NON-ORTHOGONALITY

The non-orthogonality is defined as the fraction of the total own cell carrier power that is seen as interference at the UE receiver. The non-orthogonality is used to relate downlink Eb/No to the amount of power needed to sustain a given connection. The non-orthogonality increases with the amount of multipath present in the propagation channel.

Note that historically, the degree of non-orthogonality has been historically called the ‘orthogonality factor’ despite the fact that increasing ‘orthonality factor’ actually meant reduced orthogonality of

8 Eb/No (modulated bit) of 8 dB, and modulated bit rate of 270 kbps.



the codes so this terminology is mathematically incorrect. The term non-orthogonality is therefore preferred in this document.

Non-orthogonality factors were calculated for various multipath propagation conditions for the ITU evaluation of WCDMA [23], as shown in the table below.

Propagation Model Non-orthogonality

Indoor Office A 0.1Outdoor to Indoor/Pedestrian A

0.06

Vehicular A 0.4Indoor Office B 0.25Outdoor to Indoor/Pedestrian B

0.44

Vehicular B 0.64 Table 3.8.1 ITU WCDMA evaluation non-orthogonality

A method for calculating downlink Eb/No from given test conditions can be found in 3GPP 25.942 section 13, and this can also be used to calculate the effective non-orthogonality. This method was used to calculate non-orthogonality for the 3GPP propagation models.

Propagation Model

Non-orthogonalit

y 3GPP Case 1 0.113GPP Case 2 0.673GPP Case 3 0.6

Table 3.8.2 3GPP propagation model calculated non-orthogonality factors

The values utilised by the vendors are as follows.

Nokia Nortel

Non-orthogonality

0.5 0.4

Table 3.8.3 Supplier values for non-orthogonality

A value of 0.5 is selected as recommeded by Nokia. This value lies between the figures for the more realistic propagation models of Vehicular A/Pedestrian B and 3GPP case 3.

A Non-orthogonality value of 0.5 is recommended.

3.9 OTHER TO OWN CELL CARRIER POWER RATIO

This factor is used to calculate the amount of interefering signal from other cells relative to the carrier power received from the serving cell.



The signals from other cells are completely non-orthogonal to the wanted own cell signal.

The setting of this parameter takes consideration of the fact that the UE is at the cell edge. The proposed setting of 1 suggests equal power from own cell and one adjacent cell in the case of 2 dominant local cells, or 2 adjacent cells at half the power in the case of 3 dominant local cells. While is it possible to conceive of a tougher scenarios where several other cells combine to exceed the carrier power from the own cell, in most such instances soft handover should allow the signals from several strong serving cell to be combined to counter the increased interference level.

An other cell to own cell carrier power ratio value of 1 is recommended.

3.10 UE DOWNLINK EB/NO

The derivation of downlink Eb/No is based upon the same approach as the uplink of calculating a weighted mean of compensated values from suppliers and the 3GPP specification.

The tables below summarise the Eb/No figures provided by suppliers. Not that in the case of Nortel and Siemens, downlink figures are not known and therefore the uplink figures are used with a 3 dB

Bearer Service

Data Rate [kbps]


AMR Voice 12.2 6.5 9.3 6.3Circuit 64 - 7.8 5.2Circuit 128 5 7.4 4.8Circuit 384 - 7.2 3.6Packet 64 5.5 6.2 4.4Packet 128 5.0 5.8 4.1Packet 384 4.5 5.6 3.2

Table 3.10.1 Supplier downlink (UE) Eb/No values [dB], 3 km/h users

Bearer Service

Data Rate [kbps]




AMR Voice 12.2 6.5 9.4 9.1Circuit 64 - 7.8 6.8Circuit 128 - 7.4 5.9Circuit 384 - 6.9 5.7Packet 64 5.0 5.9 6.6Packet 128 4.5 5.6 5.9Packet 384 4 5.3 5.3

Table 3.10.2 Supplier downlink (UE) Eb/No values [dB], 120 km/h users

Another source of downlink performance information is 3GPP specification 25.101, although the results provided there require conversion to obtain an Eb/No value. The derivation of the Eb/No figures from the performance requirements in 3GPP 25.101 has been done as described in 25.942, and the results of this conversion are summarised below.

Bearer Service

Data Rate

[kbps]

Case 1 Case 2 Case 3

AMR Voice 12.2 16.3 13.0 9.0Circuit

(BLER=1%)64 14.1 10.8 6.2

Circuit (BLER=1%)

144 (128)

13.8 8.5 5.4

Circuit (BLER=1%)

384 14.1 7.2 5.7

Packet (BLER=10%)

64 10.2 7.1 5.5

Packet (BLER=10%)

144 (128)

10.0 5.5 4.9

Packet (BLER=10%)

384 10.0 4.9 4.9

Table 3.10.3 3GPP derived downlink (NodeB) Eb/No Values [dB]

The compensations applied to the above figures in the above tables are the same as the downlink.

To calculated a weighted mean the following weightings were applied for the pedestrian case. The weighting for Nortel and Siemens are reduced compared to the uplink case because the figures used are derived from uplink simulation with 3 dB added to account for the lack of diversity gain.

Source Weighting

Nokia 25%Nortel 10%

Siemens 10%3GPP Case 3 25%3GPP Case 1 15%3GPP Case 2 15%

Table 3.10.4: Weighting applied for calculation of downlink 3km/h Eb/No



For the 120 km/h case, the following weightings were applied

Source Weighting

Nokia 40%Nortel 10%

Siemens 10%3GPP Case 3 40%

Table 3.10.5: Weighting applied for calculation of downlink 120 km/h Eb/No

After performing the weighted mean calculation the recommended value for downlink Eb/No are as follows:

Bearer Service

Data Rate [kbps]

3 km/h 120 km/h

AMR Voice 12.2 10.3 9.7Circuit 64 7.6 6.8Circuit 128/14

46.7 6.0

Circuit 384 6.6 5.8Packet 64 6.5 6.2Packet 128/14

45.7 5.6

Packet 384 5.3 5.2

3.4 DOWNLINK POWER CONTROL HEADROOM

As in the uplink case this parameter reflects the fact that the Eb/No values used within the link budget are receiver Eb/No values which assume power control can counter the effects of Rayleigh fading. In reality at the cell edge the transmitted power is limited by the maximum carrier power.

At a recent link budget meeting and in [10], Nokia suggest that including such a margin for power control headroom is not necessary, because the downlink power is shared between users and hence individual codes powers may peak to invert fades, but the overall carrier power should stay more or less constant. This might be true for low data rate services, but for high data rates utilising 45% of the total carrier power, this can no longer be safely assumed.

Unfortunately no simulation results for the downlink case exists. Theoretically, the above-described benefit of any averaging over users is countered by the lack of receive diversity on the downlink which would be expected to increase the power control headroom because of the deeper fading. The same value as the uplink is proposed.



A setting for downlink power control headroom of 0.9 dB for packet users is recommended.

3.12 DOWNLINK SHO COMBINING GAIN

The SHO combining gain is defined as the reduction in transmitted power when in a soft handover state compared to the power required to connect to the strongest of the cells without soft handover.

On the downlink the transmit signals from two base stations can be combined within the UE receiver. As a result, SHO on the downlink provides not only increased diversity, but an effective increase in the total transmitted power. Therefore downlink combining gain is greater than for the uplink.

Simply addition of powers from two cells gives a 3 to 1.5 dB gain in received power when the more distant cell has 0 to 4 dB increase path loss than the ‘closer’ cell. A diversity benefit can be expected on top of these figure.

Downlink link level simulation results have been performed by Nokia for pedestrian A. These show a gain of 5.3, 3.8 and 2.5 dB 9 for a path loss difference between serving cells of 0, 3 and dB [9]. These gains are rather high because of the propagation model used is subject to strong Rayleigh fading. Other Nokia simulations [10] show more modest gains of 4, 2.5 and 1 dB for path loss differences of 0, 3 and 6 dB. Within the link budget, Nokia recommend an even more modest value of 1.2 dB [7].

A setting of 1.5 dB has been selected for the downlink SHO combining gain. This considered relatively cautious given the value chosen for other to own cell interference ratio.

A downlink SHO combining gain value of 2 dB is recommended.

9 Gain assumed in tthe transmit power per cell. Nokia assume gain relative to sum of transmity powers and is hence 3 dB lower.



4. LINK BUDGET RESULTS

Spreadsheet:

4.1 UPLINK LINK BUDGET

Table 4.1.1 shows the uplink link budget calculation for pedestrian/stationary users assuming macrocell node B with MHA.

Speed 3 km/hMHA? yes

Speech Circuit 64

Packet 64

Packet 128

Packet 384

unit

UE maximum output power 21.0 21.0 21.0 21.0 21.0 dBmUE Antenna gain 0.0 0.0 0.0 0.0 0.0 dBiUE EIRP 21.0 21.0 21.0 21.0 21.0

Node B Eb/No 6.9 4.1 3.2 2.6 2.4 dBNode B noise figure 2.5 2.5 2.5 2.5 2.5 dBInformation rate 12.2 64.0 64.0 128.0 384.0 bpsNode B receive sensitivity -123.7 -119.3 -120.2 -117.8 -113.3 dBmPower control headroom 2.0 2.0 0.9 0.9 0.9 dBBase station RX losses 0.5 0.5 0.5 0.5 0.5 dBBase station antenna gain 18.0 18.0 18.0 18.0 18.0 dBUplink SHO combining gain 0.5 0.5 0.5 0.5 0.5 dBSHO slow fading margin reduction 2.0 2.0 2.0 2.0 2.0 dBInterference margin 3.0 3.0 3.0 3.0 3.0 dBReceive level at BS antenna -138.7 -134.3 -136.3 -133.9 -129.4 dBm

Path loss inc. body/slant loss 159.7 155.3 157.3 154.9 150.4 dBBody loss 5.0 2.0 2.0 2.0 2.0 dBUL slant loss 2.0 2.0 2.0 2.0 2.0 dBPath loss less body loss or slant loss

152.7 151.3 153.3 150.9 146.4

Table 4.1.1 Uplink link budget for UMTS FDD macrocell for speed of 3 km/h and assuming deployment of MHAs.



4.2 MAXIMUM DOWNLINK PACKET BEARER RATE AT UPLINK LIMIT

Table 4.2.1 shows the calculation of the maximum downlink packet bearer rate at the cell edge defined by the uplink link budget calculation.

Speed 3 km/hMHA? yes

Node B Config 40 PA, STSR

UL Speech

UL Circuit 64

UL Packet 64

UL Packet 128

UL Packet 384

Units

Node B max. carrier power 46.0 46.0 46.0 46.0 46.0 dBmCarrier loading 0.9 0.9 0.9 0.9 0.9 %Max. fract. power for packet user

0.5 0.5 0.5 0.5 0.5 %

TX code power 42.5 42.5 42.5 42.5 42.5 dBmBase station TX losses 3.0 3.0 3.0 3.0 3.0 dBBase station antenna gain 18.0 18.0 18.0 18.0 18.0 dBBS carrier EIRP 61.0 61.0 61.0 61.0 61.0 dBmBS code EIRP 57.5 57.5 57.5 57.5 57.5 dBm

UL Path loss less body/slant loss 152.7 151.3 153.3 150.9 146.4 dBDL slant loss 2.0 2.0 2.0 2.0 2.0 dBHigher frequency additional path loss

1.6 1.6 1.6 1.6 1.6 dB

Body loss 5.0 2.0 2.0 2.0 2.0 dBUL SHO fading margin reduction 2.0 2.0 2.0 2.0 2.0 dBDL path loss incl. body/slant loss

159.3 154.9 156.9 154.5 150.0 dB

UE noise figure 8.0 8.0 8.0 8.0 8.0 dBNoise density -166.0 -166.0 -166.0 -166.0 -166.0 dBm/HzNon-orthogonality 0.5 0.5 0.5 0.5 0.5Intracell interference density -167.6 -163.2 -165.2 -162.8 -158.3 dBm/HzOther to own cell carrier power ratio

1.0 1.0 1.0 1.0 1.0

Intercell interference density -164.6 -160.2 -162.2 -159.8 -155.3 dBm/HzTotal noise&interference density

-161.2 -157.8 -159.4 -157.4 -153.3 dBm/Hz

DL Eb/No 5.3 5.3 5.3 5.3 5.3 dBDL power control headroom 0.9 0.9 0.9 0.9 0.9 dB DL SHO combining gain 2.0 2.0 2.0 2.0 2.0 dBReceived code energy -99.8 -95.4 -97.4 -95.0 -90.4 dBmMax DL cell-edge packet bearer rate

327.2 413.5 380.1 419.2 460.8 kbps

Table 4.2.1 Maximum downlink packet bearer rates at uplink link budget cell edge for speed of 3 km/h and assuming deployment of MHAs and 40W STSR configuration.



APPENDIX A - EB/NO DEFINITIONS AND RELATED FACTORS POWER- CONTROL –TX-POWER-INCREASE AND POWER-CONTROL-HEADROOM

A.1 INTRODUCTION

This paper describes different parameters related to Eb/No and proposes values to use in link budgets and simulation results.

A.2 RECEIVED EB/NO

Received Eb/No is related to the average received power as follows:

Pr = Eb/NoRX.(Io+No).R

where Pr is received power, Io is the effective interference spectral density, No the noise spectral density and R is information rate.

Note that the information rate is the information rate after channel decoding. It does not include bits required for DPCCH, MAC, RLC, and associated SRB. However the received power Pr should include the overhead for such bits, so that such overheads are also included in the Eb/No value.

The received Eb/No is generally provided by link simulations, and values are dependent upon the multipath propagation channel used and the link quality requirement (FER, BLER, RBER, etc.).

A.3 TRANSMITTED EB/NO

Transmitted Eb/No is related to the average transmitted power as follows.

P̄ t=Eb/NoTX (Io+No ) R

L̄

L is the transmission loss between transmitter and receiver. The transmitted power is related to receive power as follows.

Pr = L. Pt

So why is there a difference between received and transmitted Eb/No? Unfortunately the above relation does not apply to average powers.

P̄ r≠L̄ . P̄ t



This is because the transmission loss and transmit power are not independent, as a result of power control. Under ideal power control, we can say that Pr is constant and therefore

Pt = Pr / L

The average transmit power is then given by the integral.

P̄ t=Pr ¿∫∞ ¿0 ¿¿∫ ¿(1 /L ). p(L ).dL

where P(L) is the probability of a certain transmission loss. For full Rayleigh fading and perfect (infinite dynamic range) power control, this integral is found to be infinite (integral of 1/x function from zero to infinity is infinite). Infinite average power is required to provide the infinite power in the deepest fades!

In practice, of course, the utilised transmit power is not infinite, because of 2 reasons: the multipath diversity reduces the propability of deep Rayleigh fades; and the dynamic range of the transmitter is limited. Nevertheless, it is found that fast power control does increase the transmitted power over that predicted by the received Eb/No.

For fast moving mobiles, the power control is not able to track the fades and the difference between transmitted and received Eb/No disappears. Compared to the slow moving case received Eb/No tends to rise, and transmitted Eb/No reduces.

A.4 POWER CONTROL TX POWER INCREASE

Power control TX power increase (PCTXPI) is defined as the difference between received and transmitted Eb/No.

PCTXPI = Eb/NoTX - Eb/NoRX

Nokia sometimes refer to this as the Power Rise due to uncorrelated fading.

A.5 POWER CONTROL HEADROOM

When average transmitted power approaches the peak power, it is found that receiver performance is degraded since it is no longer possible to invert deep Rayleigh fades because of the limited peak transmitter power. Therefore one needs to increase the average power over that used when perfect power control is assumed.



A important limiting case is when power control is deactivated entirely. In this case transmitted power is independent of path loss and the received and transmitted Eb/No are the same.

We define Power Control Headroom (PCH) as the difference between the Eb/No’s for power control enabled and disabled. Two cases of power control headroom apply, for received and transmitted Eb/No.

PCHRX = Eb/NoTX/RX, no PC - Eb/NoRX, pc

PCHTX = Eb/NoTX/RX, no PC - Eb/NoTX, pc

Nokia sometimes refer to this parameter as the Fast Fading Margin.

A.6 SIMULATION RESULTS

Ericsson have used simulations to quantify these effects for a Pedestrian A and B uplink channel with receive diversity [12]. Pedestrian A is much worse than Pedestrian B because of the reduced multipath. The tables below summarises their results, for frame erasure rates of 1% and 10% respectively.

FER= 1%Max – Average TX Power

Eb/No(rx)

Eb/No(tx)

Eb/No(tx)-Eb/No(rx)

Max – Average +Eb/No(tx) – Eb/No(rx)@full PC

42.3 (Full PC) 4.5 5.2 0.7 438.3 4.5 5.2 0.7 9.05.3 4.5 5 0.5 5.82.7 4.5 5 0.5 3.20 (no PC) 6.5 6.5 0 2

FER=10%Max – Average TX Power

Eb/No(rx)

Eb/No(tx)

Eb/No(tx)-Eb/No(rx)

Max – Average +Eb/No(tx) – Eb/No(rx)@full PC

43.1 (Full PC) 3.4 4.1 0.7 43.89.1 3.4 4.1 0.7 9.06.1 3.3 4.0 0.7 6.83.3 3.3 3.8 0.5 3.70 (no PC) 4.3 4.3 0 0.9

The right hand column calculates the difference the actual peak power used in the simulation and the average transmitted power which would be derived from the use of received Eb/No applicable for full power control. It



is minimised when no power control is used. In this case it is equal to the power control headroom (PCHRX).



DOCUMENT HISTORY

Issue Date Details0.1 Draft issue for comment.

Title - LINK BUDGET OFR UMTS FDD NETWORK DOCUMENT APPROVAL

OWNER/AUTHOR (SIGNED)

NAME (BLOCK CAPITALS): PETER STEVENS

CHECKED BY (SIGNED) DOCUMENT REPRESENTATIVE

NAME (BLOCK CAPITALS):

APPROVED BY (SIGNED) MANAGER

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OWNERSHIP & CONFIDENTIALITY

T- Mobile is the trading name of T-Mobile (UK). No part of this document may be disclosed orally or in

writing, including by reproduction, to any third party without the prior written consent of T- Mobile (UK).

This document, its associated appendices and any attachments remain the property of T - Mobile (UK)

and shall be returned upon request.


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