b7 gprs planning ed1

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Reference Classification: 900 000File Name: B7 GPRS Planning Guideline Ed01.doc Save Date: 2003-07-10 Revision Number: 080

3DF 01902 2710 VAZZA Edition 01 RELEASED 1/34

Professional Customer Services

GPRS Planning Guideline B7


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Contents

1 SCOPE ............................................................................................................................................ 4

2 REFERENCED DOCUMENTS............................................................................................................. 4

3 OVERVIEW: PLANNING A GPRS NETWORK ................................................................................... 5

4 GPRS GREENFIELD PLANNING ...................................................................................................... 64.1 Traffic Analysis .............................................................................................................................................64.1.1 GPRS traffic calculation............................................................................................................................. 94.2 GPRS Network Design................................................................................................................................104.3 GPRS Analysis ............................................................................................................................................124.4 Routing area and CAE data generation ......................................................................................................124.5 Reaching GPRS QoS during GPRS planning and implementation phase ...................................................... 12

5 GPRS INTRODUCTION INTO AN OPERATIONAL GSM NETWORK................................................135.1 Actual status of the GSM network ...............................................................................................................135.2 Occurred traffic and handled traffic balance............................................................................................... 135.3 Introduction of GPRS and related features/settings ...................................................................................... 14

6 GPRS ANALYSIS (CODING SCHEME AND THROUGHPUT PREDICTIONS)..................................... 15

7 ROUTING AREA PLANNING ........................................................................................................167.1 CAE-BSS Parameters Generated by A955 ...................................................................................................17

8 PLANNABLE FEATURES TO REACH GPRS QOS TARGET ................................................................ 18

9 GPRS FEATURES TO INCREASE QOS DURING PLANNING ...........................................................189.1 MPDCH and SPDCH Planning.................................................................................................................... 189.1.1 Master and Slave PDCH Concept ............................................................................................................189.1.2 Handling Primary MPDCH ...................................................................................................................... 199.1.3 Secondary Master Channels.................................................................................................................... 199.1.4 Planning Recommendation on MPDCH................................................................................................... 199.2 Radio resource and TBF management ........................................................................................................209.2.1 PDCH Dynamic Allocation ...................................................................................................................... 209.2.2 Fast pre-emption ....................................................................................................................................219.2.3 TBF Resource Management..................................................................................................................... 229.2.4 PDCH Resource Management ................................................................................................................. 229.2.5 TBF resource reallocation (radio resource reallocation)............................................................................229.2.6 Coding Scheme (CS) Adaptation process................................................................................................. 239.3 Overview on cell reselection modes ............................................................................................................249.3.1 Cell adjacencies ..................................................................................................................................... 24

9.3.2 Cell reselection criterion no PBCCH established.......................................................................................249.3.3 Cell reselection criterion PBCCH established ........................................................................................... 259.3.4 Cell Reselection at Routing Area Border................................................................................................... 269.3.5 Broadcasting of SI13 on extended BCCH ................................................................................................279.4 Features on DL TBF establishment and release............................................................................................ 279.4.1 Delayed DL TBF release .......................................................................................................................... 289.4.2 Fast DL TBF re-establishment .................................................................................................................. 289.4.3 Non-DRX feature ....................................................................................................................................299.5 GPRS POWER CONTROL........................................................................................................................... 29

APPENDIX A GSM NETWORK ENHANCEMENT FEATURES AND GPRS ..............................................30

APPENDIX B GPRS TRAFFIC ANALYSIS CALCULATION METHODS.....................................................32


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1 SCOPE

The focus of this document is the GPRS planning from AIR interface point of view. Forthis reason planning relevant integration steps, restrictions and recommendations ofGPRS features (B6 and B7) will be presented.

For the Edition 02 of this document the link to the document Radio QoS AcceptanceTest Procedures For GSM/GPRS [9] will be created. This link will help to identify whichplanning steps have an influence on which QoS KPI (Key Performance Indicator) ofGPRS.

The reader should be familiar with GSM and GPRS features of Alcatel. This documentwill help the reader to setup or integrate a GPRS network into a GSM network. ForGPRS knowledge related introduction and advanced features see [1].

In chapter 4 GPRS Greenfield planning and in chapter 5 GPRS Introduction into anoperational GSM network is described.

Chapter 6 is describing the GPRS thoughput analysis with a radio network planningtool (e.g. A955) and the details of the planning steps.

For routing area planning, chapter 7 will give rercommendations on how to split theGPRS network into routing areas.

Chapter 9 gives proposals how to integrate GPRS features to increase GPRS QoS. Thisfeatures shall be taken into account during GPRS planning to guarante QoS demandof the operator.

APPENDIX A summarizes impacts of GSM features on GPRS QoS. The presented GSMfeatures should be used to reduce interference in the network which may increaseGPRS QoS.

APPENDIX B presents three different GPRS traffic analysis calculation methods toachieve the needed TS for GPRS. The results will be used in chapter 4 or chapter 5 in

the corresponding subchapter GPRS traffic analysis.To get into contact with the Radio Network Planning Expert Center onGPRS topics, please use the intranet link of Professional Customer Services under

http://aww-mnd.alcatel.com/pcs/

Select GPRS in the Technology area

Please send your comments, update wishes referring to this document to

[email protected]

They will be considered in a next edition of the document.

2 REFERENCED DOCUMENTS

[1] 3DF 00995 0005 UAZZA GPRS/E-GPRS Radio Network Planning Aspects[2] 3DC 21150 0260 TQZZA GPRS Network Design Process in Release B6.2 and B7[3] 3DF 01907 2710 VAZZA GPRS: parameters and QoS follow-up B7[4] 3DF 01955 5283 PCZZA Radio Network Planning for GPRS[5] 3DC 21083 0001 TQZZA Evolium A9100 BTS product description[6] 3DC 21150 0263 TQZZA GSM 900 and GSM 1800 Use of High Power TRX with

TMA[7] 3DC 21150 0275 TQZZA TMA Configuration for GSM and Impact on Network

Design[8] 3DC 21150 0292 TQZZA GPRS/EGPRS Throughput Tool User Manual

[9] 3DF 01900 3060 QMZZA Radio QoS Acceptance Test Procedures For GSM/GPRS

Readership Profile

Content Summary

Service Information


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4 GPRS GREENFIELD PLANNING

GPRS Greenfield planning means dedicated analysis of GPRS network design. All GPRScells will be designed for maximum throughput performances. So the (GPRS) cellranges could be smaller, in opposite to chapter 5, as used to be in a pure GSM

network designed for speech service only.The GPRS Greenfield planning:

Traffic analysis

GPRS data traffic model

GPRS Network Design (cell design with focus on maximum throughput)

Field strength prediction (with creation of interference matrix)

Frequency planning

Network wide Interference analysis for all cell relationships

GPRS analysis

RA planning

BSS-CAE data generation

All this points will be discussed one by one in the same order in the followingsubchapters. The order is important because the output of one action is the input forthe next task

4.1 Traffic Analysis

The traffic analysis is done to have the amount of resources (frequencies) one needs tofulfill GSM+GPRS traffic. So the CS traffic demand (Circuit Switched, derived fromErlang B formula) and PS (Packet Switched) traffic demand have to be taken into

account for the capacity calculation.

The PS traffic demand (or user throughput demand) is derived from an average trafficdata volume generated by each type of GPRS subscriber. GPRS traffic volume is givenon a monthly basis as sum of used applications data volume.

Today all PS traffic values are based on assumptions until useful experiencevalues are available. The traffic values are collected in a traffic model as describedbelow.

In general, the traffic from PS services is depending on:

User profile

User behavior

Market applications and service distributions

User pro fi le

Ma rket a ppl icat ions

and se rvice distr ibut ions

User behavior Custom erQuest ionnaire

Traff ic calculat ion

T ra f fi c mod e l

Figure 2: Traffic analysis inputs for a traffic model

GPRS traffic


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A user profile defines a typical user for packet data services, using a certain amount ofapplications.

It is useful to limit the amount of user profiles to keep the calculation simple, e.g.two profiles can be introduced, business and private user as in Table 1.

Different services are possible for packet data use e.g. new designed services orservices known from the fixed network.

Market applications and user profiles are related to each other, thus someapplications are assigned to one user profile only (Table 1).

Each service is characterized by its occurrence: action time per month and therelated bit rate per action.

In some applications, the data exchange traffic is oriented to downlink, in some othersto uplink. Generally the downlink traffic is preponderant in asymmetrical applicationssuch as: web browsing, information downloading, audio downloading etc.

This shall be taken into account for the dimensioning process: so the dimensioning willbe downlink oriented.

Important is the daily distribution

Duration and occurrence time of busy hour (BH), assumption busy hour is samefor CS and PS

The user distribution over the planning area

A probable definition for the user behavior in the phase of GPRS introduction is listedbelow; a homogeneous traffic distribution over the cell area is assumed. Followingdefinitions can be only expected values for the introduction of GPRS.

GPRS subscriber percentage (%), related to the total (CS+PD) subscriber number

GPRS user profiles percentage (%), related to the total GPRS subscriber number

Geographical percentage distribution (%) of GPRS user profiles related tomorphostructure

Daily GPRS user profile activity (days/month)

As soon as more precise information will be available the user behavior can bespecified better, but for the time being, there is no use for a deeper behaviorspecification.

Table 1 summarizes exemplarily, the assumptions made for the traffic profiles ofGPRS subscribers. It gives the average data volume generated by each type of GPRSsubscriber per month based on an estimation of the used applications.

All data, which is relevant for the traffic calculation has to be collected from theoperator and submitted to network planning. To simplify the process, a questionnairewas worked out. It contains data, which the network operator should be able to give

even at early stages of GPRS introduction. The data of the customer questionnaire is atleast needed to calculate the resources needed to cope with the expected GSM+GPRStraffic. The customer questionnaire list:

a) Total amount of GSM subscribers in the network (CS+PD subscribers)

b) Blocking at air interface (speech)

c) Speech traffic per subscriber (mErl/sub)

d) Distribution of CS subscribers to different morpho classes

e) Percentage of GPRS subscribers related to the total amount of GSM subscribers

f) Busy hour occurrence for speech traffic and packet data traffic

g) User profile definitionh) Market applications definition and relation to user profiles

User profile

Market applications

User behavior

Customer Questionnaire


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i) PD user behavior/distribution

j) Daily GPRS user profile activity (days/month)

k) GPRS user profiles percentage (%), related to the total GPRS subscriber number

l) Geographical percentage distribution (%) of GPRS user profiles related to morphostructure

m) Number of (foreseen) BTS in the networkn) Distribution of foreseen/existing BTS to morph classes

o) Number (foreseen) of TRX/BTS, in accordance to morph class

Answers to the points a)-o) can be only estimated in the case of Greenfield planning.Points m), n) and o) are especially for the case if GPRS is implemented in an existingGSM network, see chapter 5.

Table 1: Exemplary Traffic model for PD

User ProfileBusiness

User ProfilePrivate

Market Application Expected duringGPRS introduction

Expected duringGPRS introduction

Mail/Month 6 -

Kbytes 20 -

Remote access (e.g. WEBdata bases general andspecific (law, medicine, ...)

Mbytes/Month 0.117=6*20 Kbyte/1024

-

Pages/Month 24 3

Kbytes 150 30

E-mail + Attachment

Mbytes/Month 3.516 0.0878

Info/Month 25 10

Kbytes 100 100

WWW


Update/Month 25 20

Kbytes 60 60

Information (e.g. Location,event, transportationservices)


Usage/Month 8 2

Kbytes 75 75

e-Commerce

(e.g. On-line shopping)


TOTAL Mbytes/Month 8.124 2.380


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4.1.1 GPRS traffic calculation

This subchapter gives the hints how to achieve the PS traffic demand with the inputs ofTable 1 (and customer questionnaire). Following definitions of user mapping and multi-service mapping shall help to categorize the quality of the three calculation methodsdescribed in clause: Three different calculations for GPRS Traffic.

User mapping defines that one certain resource can be shared simultaneously bydifferent users. Behavior in GPRS -> Packet switched service for different users on onetimeslot.

User1

User 2

User 3

User ...

TS1 TS2 TS3 TS...

Figure 3: User mapping

Multi-service mapping means that one user can use different services. The user is notdirectly mapped to only one service in the traffic model examination.

U s e r

S e r v i c e 1

S e r v i c e 2

S e r v i c e 3

Figure 4: Multi-service mapping

3 different methods are presented how to achieve needed resources to fulfill PS traffic

demand requirements. The 3 different methods will give a range of needed PDCHs(Figure 5):

of needed

PDCHs

Straight

Forward

Erlang CTool ND

lower bound upper bound

Figure 5: Different calculations for GPRS Traffic

The calculation methods differ from the usage of packet switched advantages or not(user-mapping, service-mapping), see Table 2.

Table 2: Comparison of the 3 different methods to calculate GPRS traffic

User mapping QoS per serviceMulti-service

mapping

Straight Forwardresult for PS +

_ _

Erlang Cfor PS + +

_

Traffic tool fromND, see also [2] + + +

User mapping

Multi-service mapping

Three different calculations for

GPRS Traffic


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The calculation method and results of the 3 different approaches are given in theAPPENDIX B .

Note: All calculation methods will use the Erlang B calculation for CS traffic with inputsa) and b) from Customer Questionnaire for further network planning tasks.

The straightforward calculation gives the smallest number of needed PSTSamong the traffic calculation methods. It calculates for the whole data volume, sum of

all users data, the number of PDCH TS needed to transfer this data volume, regardlessof data transfer peaks. This method is not taking into account parallel data transfer,which is the benefit of packet transfer (GPRS).

So no service attempt queuing and no service multiplexing is taken into account by thismethod. Anyhow it is a fast calculation method to get in the first step of GPRS planningan idea of minimum needed PDCH TS.

Erlang C gives for a required service attempt probability (Quantile e.g. 90 %, Quantile:Specific elements x in the range of a variate X are called quantiles) and the queuedelay time of it (e.g. 2 s delay can be set if no resource is available at service attempt),the number of needed resources (TS).

The result of Erlang C will give the biggest number of needed PDCH TS among

the presented packet traffic calculations. The reason is that a constant data flow isconsidered which is not the case for different applications like WAP. So for all differentservices the PDCH TS with Erlang C has to be calculated and summarized. Afterwardsthe sum of PDCH TS for the different services leads to an over dimensioning.

This method can be used to give very fast a planning result on how many PDCH asmaximum can be expected.

The traffic tool, described in [2], is the more exact method to calculate the neededPDCH compared to the above calculation methods. Another important point is that thetraffic tool is an automated tool (attention only ND internal use). The result of thiscalculation will be most probably between the above calculation methods.

Additionally operator agreed/suggested handling of GPRS channels must be fixed. This

is for example the usage of:

Activation of MPDCH or not, see also chapter 7

BCCH combined mode or not

Usage of Delayed DL TBF Release or not, see also chapter 9.4.1

QUALITY OF SERVICES [Volume @BH, Page size (KBytes), Queue delay (seconds),Quantile (%), Bit rate (kbit/s)]

The traffic tool can calculate the result:

TS needed for CS traffic and signaling in DL/UL

TS needed PS traffic and signaling in DL/UL

TRX calculation for CS and PS with application of reuse of CS TS for PDCH (PS)when dynamic/smooth PDCH adaption and /or fast preemption feature isactivated

4.2 GPRS Network Design

The knowledge of the amount of timeslots makes it possible to go to the next step ofGPRS network design process. The user throughput demand is then related to a dailytraffic occurrence (user capacity) and in combination with the CS traffic demand, theneeded equipment amount is calculated:

Number of timeslots which may be reserved for GPRS in normal and high loadstate of the BSC

Number of timeslots which have to be reserved exclusively for GPRS

Calculation steps and resultcomparison

Straight Forward Result for PS

Erlang C calculation for PS

TRAFFIC TOOL from ND


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Number of remaining timeslots for CS traffic

The result of traffic analysis, chapter 4.1, gives the standard BTS configuration for thedifferent traffic areas. The traffic areas are most commonly linked to a specific morphoclass. Please consult the BTS product description for the selection process [5].

For the GPRS network design the field strength prediction is done as for the GSMnetwork planning e.g. with the radio network planning tool A955. After field strength

calculation the mutual interference calculation is done in A955. These results will beused as input for a GSM/GPRS frequency planning, in A955 this is done in the AFPmodule (automatic frequency planning).

The cell specific interference calculation is done with the results of the GSM/GPRSfrequency planning. The cell specific interference calculation will be used to identify lessinterfered frequencies for TRX assignment.

Some general considerations apply independently from the BSS software release:

GPRS shall be mapped on the TRX(s) with the best radio quality (lowestinterference probability); this can be any TRX in the cell.

It is recommended that the BCCH TRX is among the carriers which carry GPRStraffic due to the better frequency reuse of the BCCH.

This is done by:

Identification of less interfered frequencies and their ranking

Assigning the preference for PS traffic handling to the best ranked frequencieswith the help of the parameters.

In B7 up to 16 TRX per cell are available for GPRS service. So a differentiation of GSMand GPRS TS allocation priority on the TRX must be fixed during planning. Theallocation priority for GPRS shall be set according to GPRS QoS needs.

The BCCH TRX with bigger frequency reuse distance shall be favored for GPRS TSs(Slave PDCH and MPDCH) with the help of the parameters TRX_PREF_MARK andGPRS_PREF_MARK. The better the ranking of a TRX is (after cell specific interferencecalculation), the higher its GPRS_PREF_MARK value shall be.

Case no frequency hopping:

Set all TRXforeseen with only CS service to

TRX_PREF_MARK 0 (Range 1-7)

GPRS_PREF_MARK=0

Set all TRXfavoring for PS service allocation (with CS traffic allocation possibility)

TRX_PREF_MARK = 0

GPRS_PREF_MARK0 (Range 1-3) (according to cell specific interference

calculation) If the required number of TRX for GPRS =1, the BCCH has to be preferably

selected

If the required number of TRX for GPRS =n (with 2


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5 GPRS INTRODUCTION INTO AN OPERATIONAL GSM NETWORK

Following aspects are considered if GPRS is introduced into a mature GSM networkwithout network design changes, different to the approach of GPRS Greenfieldplanning (chapter 4). If the operator foresees design changes due to GPRS QoS

requirements than traffic analysis and GPRS network design tasks has to be donebefore the GPRS introduction step.

5.1 Actual status of the GSM network

All GSM network enhancement features and GSM network problems, mainly GSMQoS and interference, shall be fixed before GPRS is implemented.

If a new network design and frequency planning is developed to improve GSM QoSand interference, then the implementation of this design should be done before GPRSis implemented.

GSM QoS andInterference problems?

see chapter 8

Actual GSM capacity

enough to cope withGSM and GPRS traffic?see chapter 4.1

New Frequency plan

foreseen?

see chapter 4.2

RA planning

CAE data generation

yes

yes

yes

no

no

no

no

yes

GSM problem fixing

no

Introduction of GPRS

and related

features/settings.

Check GPRSthroughput map

GPRS

Introduction

How

toreach

GPRSQoS

TasksbeforeGPRS

Introduction

Increase capacity

Implement Freq. plan

GPRS QoS reached?Plannable features to

reach GPRS QoS target

Optimize GPRS

parameters if needed

Add new GPRS

features if needed

GSM QoS andInterference problems

Figure 6: GPRS Implementation steps into an existing GSM network

5.2 Occurred traffic and handled traffic balanceThe GPRS QoS requirements from the operator define the needed GPRS capacity.

GSM QoS and Interference

New network design/frequencyplanning

GPRS QoS requirements


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Before the GPRS planning tasks begin the operator should fix GPRS QoS per user inrelation to specific definitions for user and used service:

Volume @BH (Kbytes), Page size (Kbytes), Queue delay (seconds), Quantile (%),Bit rate (kbit/s)

The calculation of expected GPRS traffic can be done according to GPRS trafficcalculation in chapter 4.1.1. Following results will be then available:

TS needed for CS traffic and signaling in DL/UL and

TS needed for PS traffic and signaling in DL/UL.

The knowledge of the amount of TS and so TRX/frequency makes it possible to go tothe next step of comparing actual capacity in the GSM network to needed capacity forGSM and GPRS.

If the resources are enough to cope with the additional GPRS traffic the frequencyplanning in chapter 0 and the MPDCH planning (chapter 9.1) can be done.

If the resources are not enough to cope with the GPRS traffic additionalTRX/frequencies must be allocated to the sites with less traffic capacity.

A new frequency planning should be done when a not negligible amount of newfrequencies have to be added to a planning area to fulfill (GSM+GPRS) capacityrequirements.

5.3 Introduction of GPRS and related features/settings

The prerequisites for a GPRS analysis (chapter 6) are following taskssee also (chapter 4.2):

Field strength prediction

Interference analysis

If new sites after GPRS analysis are required to fulfill operators GPRS requirements, anew frequency planning with a certain frequency band range planning has to be done.

The routing area (RA) planning is a must for GPRS introduction into GSM network, seechapter 7 for details on RA planning and CAE data generation.

GPRS QoS increasing tasks to be done are depending on dimensions of QoSrequirements. What kind of tasks and references can be done to increase GPRS QoS isgiven below.

GPRS DL QoS increasing features as in chapter 9 (especially 9.2, 9.4) and APPENDIXA can be added to the GPRS planning.

The gains of the features should be not included in the calculations of needed capacity(result from chapter 5.2). The gain should be used as buffer to fulfill GPRS QoSrequirements from operator easily during GPRS planning and GPRS acceptance test.

Following tasks can be done according to dimensions of GPRS QoS requirements:

GPRS frequency separation in a cell can be done if TRX number in the cell is 2,see chapter 0

Introduction of GPRS Master channels (MPDCH), see chapter 9.1, to separateGPRS and GSM signalingOpen question: Penetration rate of GPRS MS which can decode MPDCH

The parameters for the PDCH dynamic allocation can be set according to theGPRS QoS requirements e.g. the weaker the GPRS requirements are the morebuffer TS for GSM can be reserved with a low value of MAX_PDCH, for details seechapter 9.2.1

TBF resource management parameters shall be fixed according torecommendations in 9.2.3

Expected GPRS traffic

Resources are enough for GSMand GPRS

Resources are notenough forGSM and GPRS

Prerequisites for GPRS analysis

Routing area, CAE data

Increasing GPRS QoS


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6 GPRS ANALYSIS (CODING SCHEME AND THROUGHPUT PREDICTIONS)

The GPRS analysis contains the evaluation of coding scheme and throughput coveragebased on Interference (C/I).

Field strength analysis, frequency planning and interference analysis, which can bedone with A955, will give the relevant boundary condition to analyze GPRS codingscheme distribution per cell and/or network. The coding scheme prediction will define

throughput performance of GPRS cell/network.

The description how to achieve following coding scheme and throughput prediction inthe radio network planning tool A955 V5 is given in [4].

The coding scheme predictions shall be used to identify areas where the throughputrates are not reached and to decide on measures, which can be done to satisfy theoperator request, e.g.:

Low coding schemes in dense urban network will probably indicate interference

Low number of time slots in lower urban network will probably indicate the needof new sites

Legend (CS value)

CS 4

CS 3CS 2

CS 1

Figure 7: Network wide coding scheme distribution (C/I based)

Legend (kbit/s)

19..20 kbit/s

16..18 kbit/s

14..15 kbit/s

7..13 kbit/s

< 7 kbit/s

Figure 8: Network wide GPRS throughput distribution (C/I based)

Coding Scheme and Throughputpredictions


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7 ROUTING AREA PLANNING

Each GSM/GPRS cell is additionally to CI and LAC characterized by:

Routing Area Code (RA_code) send on SI13; range 0255

RA_colour send on SI3 and SI4; range 07

Introducing RAs, which should be smaller than LA, will reduce the additional signaling

load in a GSM network due to GPRS paging. So the signaling effort for GPRS paging ismore focused to a smaller area.. Location Area (LA) planning is done in accordance tothe common rules for circuit switch (GSM) planning; no extra adaptation (e.g. on theneighbor list) has to be made for PS (packet switched) services.

Routing Area (RA) planning follows, as long no further experiences are available therules of the common LA assignment, e.g. avoid roads with fast moving traffic throughRA. As a consequence, the assignment of the cells belonging to RA has to be donesuch as to minimize signaling load on the cell.

The RA planning consist of:

Assignment of each cell to a RA

Assignment of the RA_code to a RA

Assignment of a RA_colour to each cell

The following rules apply:

One RA must belong to only one LA; it is not possible to define a RA across a LAborder (e.g. one cell from LA1 and two cells from LA2)

A RA can contain one or several cells

One cell can not belong to two RA

Cells from one BTS can be allocated to different RA

The maximum number of RA in a LA is 256 (0..255)

It is possible to reuse the RA_Colour in a LA

Two adjacent RA in a LA shall have different RA_Colour (recommended but notmandatory rule)

LAC can have the same 'digit' like the RA_code, e.g. LAC =2 with RAC =2

The network operation mode should be the same in each cell of one routing area(3GPP 4.18)

RA planning depends on different input, e.g.

Number of RA in a LA,

Number of cells belonging to a RA and

Number of RA_Codes per LAIt is recommended to set RA_code (RA1) RA_code (RA2) in neighbor routing areasof different location areas.

For RA_colour planning the recommendation is RA_colour (RA1) RA_colour (RA2).Possible is also RA_colour(RA1)=RA_colour(RA2). However the first solution enhancesfaster RA changes.

Particularly the cell reselection together with a LA and RA update can largely impact theaverage throughput if the RA and LA update procedures during reselection do not workefficiently. So RA should be not to small to avoid often RA changes

RA as big as LA =>1 RA_Code (same for each cell) per LA, 1 RA_colour (same foreach cell) per LA

The expense of this implementation is low.

Impact on RA_code planning

General info

1. Step Network with lowGPRS/E-GPRS traffic


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The LA is split into maximum 8 RA, see figure 3.

This is also valid for the case when a LA size is bigger than the BSC size.Reason: it is possible with Alcatel to expand the LA size over the BSC area (e.g. it ispossible to have 2 neighbor BSC areas in one LA -i.e. with the same LAC- for CSservices). Since PS services bring additional paging load it is recommended in this caseto split the LA size into smaller RAs

RA_code planning: For each RA in a LA one unique RA_Code is assigned. A balancednumber of cells per RA need to be acquired; however for identified hot spots anunbalanced assignment is possible (smaller RA for hot spots).

RA_colour planning: For each RA in a LA one unique RA_Code is assigned but withdifferent RA colours

This step represents a reasonable split of the LA into RA if packet data traffic rises. Itcan also be carried out right from the start to be prepared for the traffic growth. Theplanning effort is medium.

RA_code=0RA_colour=0


RA_code=2RA_colour=2 RA_code=3RA_colour=3





RA0

RA2

RA4

RA6

RA1

RA3

RA5

RA7

Figure 9: LA with maximum 8 RA's with allocated cells and RA_Codes

LA can contain up to 256RA, see figure 4.RA_Code planning: For each RA in a LA one unique RA_Code is assigned.

RA_Colour planning: since the number of RA in a LA is larger than 9, the RA_Colourreuse is necessary, and a large-scale planning is recommended.

Adjacencies of RA's with the same RA_Colour shall be avoided (not mandatory).

.







RA_code=6RA_colour=6 RA_code=7RA_colour=7



RA0

RA2

RA4

RA6

RA1

RA3

RA5

RA7

RA8 RA9

Figure 10: LA with maximum 256 RA's with allocated cells and RA_Codes

7.1 CAE-BSS Parameters Generated by A955

If A955 is used as planning tool it allows an automatic CAE-Data output generation.Additionally to the common BSS parameters (like CI), there are now GPRS related BSSparameters, which have to be set by the radio network planner. A summary for the

GPRS data is given in table 3. RA_Colour and RA_Code are results of the RA planningprocess.

2. Step: Network with mediumGPRS/E-GPRS traffic

3. Step: Network with highpacket data traffic


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Table 3: BSS CAE parameters for GPRS

Name Description Value

ENABLE GPRS Enables / Disables GPRStraffic within the cell

0: disabled1: enabled

RA_Colour Routing area colour code of

the cell

0 ... 7

RA_Code Routing area code for GPRS 0 ... 255

8 PLANNABLE FEATURES TO REACH GPRS QOS TARGET

GSM QoS and Interference problems if existing shall be fixed, e.g. by

Introduction of Frequency Hopping

GSM Power Control (UL)

If the GPRS QoS is still not reached, then

New GPRS features as mentioned in chapter 5.3 and listed in chapter 9 have tobe implemented

If still the GPRS QoS requirement is not fulfilled, then

An optimization campaign on parameters has to be started

Use of unique values of (GPRS) parameter settings has to be checked

Use of latest Alcatel default parameters

Use of parameters recommendations from PCS department

Optimize parameters as defined in chapter 9 and [3] for the differentfeatures, if implemented in the network

TMA (Tower Mounted Amplifier; [6],[7]) from hardware point of view can beconsidered to increase UL throughput, see also chapter 9.5 GPRS power control.

9 GPRS FEATURES TO INCREASE QOS DURING PLANNING

Details on following features in this chapter can be found in [1].

9.1 MPDCH and SPDCH Planning

The enabling of MPDCH and the decision to allocate them dynamic or static isdepending on

Traffic capacity the operator has for GSM and GPRS

Traffic capacity the operator can reserve directly to GPRS

Amount of traffic for GSM (Voice, SMS signaling, Location Area Update signaling)and GPRS (data, signaling, Routing Area Update signaling)

Subscriber distribution per service and area

Mobility (cell reselection) of users during GPRS transfer

Following subchapters will give hints for the usage and planning of MPDCH.Figure 11 describes in a flowchart the decision process for MPDCHs.

9.1.1 Master and Slave PDCH ConceptPrimaryMaster Channel= PBCCH + PCCCHTwo types of Master Channel


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If the available TS are not scarce

Operator wants the GPRS MS to perform autonomous cell re-selectionbased on C31 and C32 criterion

Dynamic Primary Master Channel

If the CS signaling channels CCCH getting overloaded due to highGPRS traffic and signaling in addition to CS signaling

N O M P D C H

L o w p r io r it y f o r G P R S o r l o w G P R S t r a f f i c ?

S t a t i c M P D C H ( D y n a m i c M P D C H )

Y E S

G P R S s ig n a l i n gc o n g e s t io n

E n a b l e s e c o n d a r y M P D C H s d e p e n d i n go n G P R S s i g n a l i n g n e e d

N O

N OY E S

Figure 11: MPDCH planning flowchart

9.2 Radio resource and TBF management

In the following subchapters the impact of B7 extensions on GPRS network planningtasks will be discussed on following points

9.2.1 PDCH Dynamic AllocationIn B7 the subdivision between PS data service and CS service is done dynamically,depending from the actual load in the cell.

There are 2 PDCH adaptation algorithms depending on traffic load variations:

A basic (since B6.2) and

Smooth/enhanced PDCH adaptation (since B7, recommended to be used)

Basic PDCH dynamic allocation

Basic PDCH dynamic allocation is not recommended to be enabled.

The load evaluation process is too slow in B6.2 (about 2mn are needed to detect highload before pre-emption is undertaken). Second drawback is, that during high loadsituation more PDCHs can be closed as needed for GSM speech traffic

Smooth/Enhanced PDCH adaptation to traffic load variations

Smooth and dynamic adaption of PDCH (also called fast adjustment of radioresources) with MAX_PDCH_DYN shall be used together with soft and fast pre-emption feature:

Featureis enabled by EN_DYN_PDCH_ADAPTION in the MFS; if disabled theMFS works as in B6.2 (Basic PDCH dynamic allocation), but fast pre-emption canbe still used.

The number of PDCHs left for GPRS in high load situation is a dynamicvariable, MAX_PDCH_DYN (calculated by BSC, for each cell specifically,

Drawback of Basic PDCHdynamic allocation

Improvement in B7B7B7B7


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The pre-emption is achieved by a PS call drop

Long T_PDCH_PREEMPTION times will occupy TS needed for CS traffic

9.2.3 TBF Resource Management

The strategy of the TBF resource sharing is to use the PDCH resources in a mosteffective way, that means not to waste a PDCH just with one user and therefore to

limit the available PS capacity.

The system will try to fill each PDCH with in this parameter N_TBF_PER_S/MPDCHdefined number of TBF, before requesting a new radio resource. The radio blocks oneach timeslot will be equally distributed among the users assigned on a channel.

If no new PDCH can be allocated the number of users per PDCH will be increased toMAX_UL/DL_TBF_S/MPDCH.

On the other hand, the more users (different TBFs) share a PDCH, the less effective thedata flow and the longer the download or upload time is.

A trade-off has to be done between the radio resource capacity sharing and optimumdata throughput.

Since GSM speech service users are still to be preferred, it is recommended toset N_TBF_PER_SPDCH1 (e.g.=2). For example, if the N_TBF_PER_SPDCH=2and CS-2 is used, the bit rate per MS will be 6.0 kbit/s (=12/2) per used timeslotfor this MS.

If operators goal is to maximize the PS throughput thenN_TBF_PER_SPDCH=1 is recommended.

In B6.2, if all GSM usable TSs are active, busy or full, a new CS call suffers from hardblocking. In this case the B7 feature PDCH fast pre-emption can increase the chancefor successful CS TS allocation; see above chapter 9.2.1.

9.2.4 PDCH Resource Management

Multislot access is the allocation of more than one PDCH to one MS (multislot access).However to prevent one multislot MS to use too many PDCHs each time it wants totransmit data (detriment of other users), following parameter is used:

MAX_PDCH_PER_TBF

Maximum number of PDCHs, which can be allocated to a single TBF (or MS)

Range: [1..5], default value: 5 (due to todays MS capabilities)

A few multi slot mobiles can occupy all resources with the default value ofMAX_PDCH_PER_TBF. Thus the parameter has to be set, depending from the expectedload and in combination with N_TBF_PER_S/MPDCH to reflect operators strategy onGPRS QoS.

9.2.5 TBF resource reallocation (radio resource reallocation)

The radio resources (PDCHs) allocated to a TBF are not changed during the TBFlifetime. The probability of long-lasting sub optimal TBF is highly increased.

With the feature TBF reallocation, the radio resources allocated to a TBF can bechanged during TBF lifetime, which increases successful and efficient TS allocation(according to multislot capability) during ongoing data transfer for PS case.

EN_RES_REALLOCATION is enabling / disabling the Radio Resource reallocationfeature per trigger and per BSS

All events that can trigger a TBF resource re-allocation shall be considered:

Trigger T1 (target maintain a TBF alive when its PACCH is fast preempted)

Drawbacks of Fast pre-emption

User multiplexing

Radio Network Planning Impacts

Multislot access


Situation in B6.2

Resource re-allocation in B7



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Trigger T2 (target attempt offering more PDCHs to an MS upon concurrent TBFestablishment):

Trigger T3 (target periodically attempt offering more PDCHs to an MS which has aTBF in the direction of the bias with less PDCHs than it can support according toits multislot class)

Details to the triggers can be found in referenced documents [1] and [3].

The advantage of the feature TBF resource reallocation is to serve a better PDCHallocation to a TBF (throughput can be optimized), according to the available radio,transmission, DSP and CPU resources, during establishment and lifetime of TBF.

In B7 the evaluation function to determine if the TBF can get a better allocation isbased on the number of PDCHs that the TBF can be mapped on and not on thethroughput the TBF will get on these PDCHs.Consequence: in certain cases, available PDCHs will not be used for TBF re-allocation,whilst using them would have improved the TBF throughput

9.2.6 Coding Scheme (CS) Adaptation process

Recommendation: Enable Coding scheme adaptation mechanism in GPRS RLC

acknowledged, un-acknowledged mode with parametersEN_CS_ADAPTATION_ACK/EN_CS_ADAPTATION_NACK), default=enabled.

Different quality threshold are introduced in B7 to optimize the B6.2 coding schemeadaptation algorithm, distinguished by

UL/DL

Usage of frequency/no-frequency hopping

RLC mode of operation (acknowledged or non-acknowledged)

Table 4: Coding Scheme change decision

Current

codingscheme

Increasing the coding

scheme number

(CSI --> CSi+1)

Decreasing the coding scheme

number

(CSi --> CSi-1)

CS1AV_RXQUAL_LT CS_QUAL_ XX_1_2_Y_Z + CS_HST_XX_LT

OR

AV_RXQUAL_ST >CS_QUAL_ XX_1_2_Y_Z + CS_HST_XX_ST

XX = DL or UL

Y = FH or NFH, for Frequency Hopping or Non-Frequency Hopping (see annex A.1)

Z = ACK or NACK, for RLC acknowledged or non-acknowledged modes

For the calculation of AV_RXQUAL_LT/AV_RXQUAL_ST see [1].

In B6.2 the hysteresis value is recommended to be 1.0. This guarantees an anti pingpong of coding scheme adaptation on the field.

The parameter TBF_CS_DL defines maximum number of consecutive PACKET DLACK/NACK messages lost in UL (not received by the BTS) on the radio interface beforechanging the CS in the DL from CS 2 to CS 1. Range: 1 to 15, default value: 6

The parameter TBF_CS_UL defines the maximum number of consecutive invalid or lostUL RLC data blocks from the MS having a monoslot TBF before changing the coding

Advantages

Drawback


Hysteresis: CS_HST_XX_LTCS_HST_XX_ST

TBF_CS_DL

TBF_CS_UL


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scheme to CS1. For a multislot TBF, TBF_CS_UL_limit:= TBF_CS_UL * n_allocated _TS.Range: 1 to 64, Default value: 32

9.3 Overview on cell reselection modes

When the MS is in GMM standby state, the SGSN has the knowledge of the MSlocation on routing area (RA) basis. When changing a RA, the MS performs a RA

update procedure to inform the SGSN about its new RA.

When the MS is in GMM ready state, the MS location is known by the SGSN on a percell basis. After performing the cell reselection, the MS shall indicate to the SGSN itsnew serving cell through a cellupdate procedure. Table 5 shows the different cellreselection criterion as a function of the network control order (NC) parameter, GMMstate and the presence of PBCCH in the serving cell.

Table 5: Cell reselection criterion parameters

NetworkControl Order

parameter

MS GMMState

Mode of cellreselection

Presence ofthe PBCCH

Absence ofthe PBCCH

Standby MS autonomouscell reselection(NC0 mode)

C1, C31, C32 C1, C2

NC0

(in B7)Ready MS autonomous

cell reselection(NC0 mode)

C1, C31, C32 C1, C2

NC1 Not supported in B7

NC2 Not supported in B7

9.3.1 Cell adjacencies

Independent from the presence of the MPDCH:

GPRS cell adjacencies are same in packet idle mode as in packet transfer mode.

GPRS cell adjacencies are set equal to the GSM cell adjacencies (i.e. theBA(GPRS) list = BA(BCCH) list )

So it is still possible to reselect a cell without GPRS service (if in the target cell GPRS isdisabled). For this reason it is recommended to enable the GPRS service on all cells inorder to prevent a MS to reselect a cell without GPRS support

9.3.2 Cell reselection criterion no PBCCH established

The GPRS MS triggers cell reselection according to GSM cell reselection criteria if

MPDCH (PBCCH ) is not enabled:Generally optimized GSM/CS parameters for cell reselection shall be kept also for PScell reselection

TEMPORARY_OFFSET and PENALTY_TIME

High TEMPORARY_OFFSET values makes it more difficult to reselect this cellduring PENALTY_TIME

Used to avoid that fast MS reselect a lower layer cell

CELL_RESELECT_OFFSET

Using different offsets for the frequency bands gives different reselectionpriorities

The higher the value is, the higher the probability is to reselect this cell

Standby state

Ready state




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9.3.3 Cell reselection criterion PBCCH established

In B7 only the MS can trigger cell reselection according to network control orderparameter NC0, see Table 5, if the following conditions are satisfied:

1. Path loss criterion (C1) for the current serving cell falls below zero. This indicatesthat the received signal level of the serving falls below GPRS_RXLEV_ACCESS_MIN

2. A neighbor cell is seen as being better than the serving cell.

C2 criterion is not used; instead the cell ranking criterion C32 and possibly C31criterion are used.

In non-hierarchical networks C32 is used to rank the cells

In hierarchical networks, thesignal level threshold criterion parameter (C31)is also used with the C32 criterion parameter to find the best-ranked cell

Basically, the mobile station considers the cells that have a positive C31 value and sortsthem according to their absolute GPRS_PRIORITY_CLASS. Then, cells having thehighest priority are sorted according to their C32 values.

If no cell has a positive C31 value, the GPRS_PRIORITY_CLASS is not considered, andall cells are ranked according to the C32 criterion only.

See GSM 05.08 and 03.22 recommendations for details of GPRS reselection process.

Generally optimized GSM/CS parameters for cell reselection can be kept also for PScell reselection.

If during cell reselection different behavior for GPRS MS as for GSM MS is wished, thenthe following parameters can be tuned to achieve the required behavior:

GPRS_RXLEV_ACCESS_MIN, GPRS_RXLEV_ACCESS_MIN(n) (on PBCCH) is usedinstead of RXLEV_ACCESS_MIN (on BCCH): minimum received signal level at theMS required for access to the system; default = -96 dBm

If many GPRS attach or PDP context activation failures occur, then increasingthis value can improve the situation. Before this task is done the network

shall be checked for interference and the frequency plan is correct. On the other hand the value should not be too high. This would cause that

GPRS coverage holes are created. The GPRS cell reselection success rate willgive the indication of GPRS coverage holes

GPRS_MS_TXPWR_MAX_CCH, GPRS_MS_TXPWR_MAX_CCH(n) (on PBCCH):maximum MS transmission power level to access the system.

GSM900 default = +43 dBm, GSM850 default = +39 dBm,GSM1800/1900 default = +30 dBm

GPRS_TEMPORARY_OFFSET(n): Negative offset used for MS cell reselectionprocess in neighbor. Range: 0 to infinity dB; default value=0 dB

High TEMPORARY_OFFSET values makes it more difficult to reselect this cellduring PENALTY_TIME


GPRS_PENALTY_TIME(n): Time during which GPRS_TEMPORARY_OFFSET is activein neighbour cells. Range: 10 to 320 sec; default value=10 sec


GPRS_RESELECT_OFFSET(n): Permanent offset for GPRS cell reselection inneighbor cells. Range: 10 to 320 sec; default value=10 sec

Using different offsets for the frequency bands gives different reselectionpriorities

The higher the value is, the higher the probability is to reselect this cell

Triggers cell reselection

Choosing the Target Cell



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HCS_THR, HCS_THR(n) HCS signal strength.

Range: 110 to 48 dBm; default value=84 dBm

Used to give different priorities to the cells in hierarchical cell structures

GPRS_PRIORITY_CLASS, GPRS_PRIORITY_CLASS(n) HCS priority of the servingand adjacent cell, used in NC0. Range: 0 to 7; default value=0

Used to give different priorities to the cells in hierarchical cell structures

9.3.4 Cell Reselection at Routing Area Border

4 cell change possibilities exists in GPRS

Intra BSC, intra SGSN cell update (cell A, B belong to the same RA 1 andconsequently to the same BSC 1)

Intra BSC, intra SGSN RA update (cell A belongs to RA 1, cell B belongs to RA 2,RA 1 and RA 2 A belong to the same BSC 1/SGSN 1)

Inter BSC, intra SGSN RA update (cell A belongs to RA 1/BSC 1, cell B belongs toRA 2/BSC 2, BSC 1 and BSC 2 belongs to the same SGSN 1)

Inter BSC, inter SGSN RA update (cell A belongs to RA 1/BSC 1/SGSN 1, cell Bbelongs to RA 2/BSC 2/SGSN 2, where SGSN 1 and SGSN 2 are linked to thecommon GGSN)

The CS specific parameter CELL_RESELECT_HYSTERESIS (range: 0..14 dB; default= 6dB) broadcasted over the BCCH allows finer tuning of cell reselection at RA borders tolimit the ping-pong effect when a MS is changing

The RA in GMM Standby state

The cell in GMM Ready state

Note, that this is the same parameter used for CS services to avoid unnecessary LAchanges. This parameter is particularly important in networks without PBCCH, which

are multiband/multilayer GPRS networks to delay cell reselection in packet transfermode.

Generally optimized GSM/CS parameters for cell reselection can be kept also for PScell reselection. For cells, which are not at location area borders different values ofCELL_RESELECT_HYSTERESIS can be tuned to optimize GPRS reselection and RAupdate. This will not have an impact on GSM location area update procedure.

GPRS-specific parameters broadcasted over the PBCCH allow finer tuning of cellreselection at RA borders:

GPRS_CELL_RESELECT_HYSTERESIS

RA_RESELECT_HYSTERESIS

C31_HYST

Case of cell reselection together with LAand RA updates

Among others, a bad efficiency of RA, LA update procedures during reselection causea low average throughput. Especially the cell reselection together with a LA and RAupdates can largely impact the average throughput; reason: the LA+RA update is fullydependent of the MS. There may be e.g. differences on a MS basis concerning theorder (which update is triggered first), the number of repetitions in case of no SGSNanswer. The only solution to speed up this kind of mobility procedure is to have a Gsinterface (MSC-SGSN) in NMO1 (network mode of operation). This will enable acombined LA and RA update fully controlled by the MS.

The following parameters offer more flexibility than CELL_RESELECT_HYSTERESIS and

can be set to GPRS-specific values. The intention is to avoid repeated cell reselectionsbetween cells from different RA's, in order to limit signaling load due to RA updateprocedures and to limit the risk of paging messages being lost during RA change.

PBCCH not established in theserving cell

Important hint


PBCCH established in theserving cell

Remark



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These parameters are taken into account in the computation of the C31 and C32criteria. The precise way they are used depends on whether the mobile station is in theSTANDBY or READY state (see ETSI standards GSM 05.08)

GPRS_CELL_RESELECT_HYSTERESIS: Additional hysteresis which applies in Readystate for cells in same RA, Range: 0 to 14 dB; default value=4 dB

RA_RESELECT_HYSTERESIS: This parameter indicates in STANDBY and READY

state the additional hysteresis, which applies when selecting a cell in a newRouting Area to limit the ping-pong effect. Range: 0 to 14 dB; default value=8 dB

C31_HYST: Determines whether an additional cell hysteresis i.e.GPRS_CELL_RESELECT_HYSTERESIS shall be applied to the C31 criterion.Range: no or yes; default value = no

9.3.5 Broadcasting of SI13 on extended BCCH

The feature is also named Fast Broadcasting of GPRS SI in Alcatel documentations.

The extended BCCH is achieved by changing the structure of the BCH multiframe inGSM: if the BSS parameter BCCH_EXT=enable (default=disable), than the frames6,7,8,9 are filled with BCCH frames instead of CCCH frames. The BCCH Ext channel

shares with the PCH and AGCH channels the resource of this CCCH on a block-by-block basis.

If master channel is not enabled and there is no lack of resources/capacity the featurecan be enabled by BCCH_EXT=enable

Benefits

Additional information can be sent on BCCH via SI 13 (for GPRS), SI 16 (forSoLSA), SI 17

Faster GPRS cell reselection for cells in GSM 1800 (rough expected gain: upto 2s (max), up to 1s (as a mean value))

Shorter data transfer interruption time during a cell reselection

Improves the network quality, as seen from the end-users

Drawbacks

Less CCCH capacity available;

Feature is not supported with BTSs equipped with FUMO and DRFU TRXs

9.4 Features on DL TBF establishment and release

3 different features are presented here which preemptively delay the TBF release tospeed up the setup of subsequent TBF. Their success depends on the users downloadbehavior e.g. how often pages are changed and the content of the downloaded http

looks like. For Web browsing and WAP applications where the PS traffic is bursty, thegain of the features to delay TBF release will be very high.

The 3 features are complementary and can be activated independently from eachother. Delays to start download of new LLC PDU depending on feature:

Delayed DL TBF release: zero delay on download of new LLC PDU

-> No new TBF required

Fast DL TBF re-establishment: Round trip delay + polling

-> New TBF required


Remark


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After reception of the final block by the MS and after the sending of the last PACKET DLACK/NACK message, the MS still listens on the PACCH during T3192 sec; duringT3192 this allows:

The BSS to send again the last DL RLC data block in case of MSacknowledgement is not received

The BSS to re-establish a DL TBF on the PACCH of the previous DL TBF (i.e. to

send a PACKET DL ASSIGNMENT message on the PACCH); this allows a fast DLTBF re-establishment without impacting the (P)CCCH resources; i.e. a new TBF isestablished but with the parameters of the old TBF (TFI, TAI)

T3192 > MS-BSS roundtrip delay + RRBP maximum duration (120ms)

T3192 = 1000ms when non-DRX mode is not activated

T3192 = 500ms when non-DRX mode is active

Remark: while T3192 is running, the MS cannot request the establishment of an ULTBF. However, while T3192 is running it is possible to undertake a fast DL TBF re-establishment.

9.4.3 Non-DRX featureSince B7, even with the SPLIT_PG_CYCLE feature, DRX mode may lead to a still quitelong downlink establishment time as compared to the duration of the data transferitself. This establishment time is significantly reduced if the new downlink TBF closelyfollows a previous one (up- or downlink). Therefore the Non DRX feature is introduced;it keeps the MS out of DRX mode during DRX_TIMER_MAX (Non DRX timer).

Higher downlink throughput and shorter transfer delay for cell reselection and burstydownload application (HTTP, WAP).

The Non-DRX feature should be enabled as default with DRX_TIMER_MAX=2 sec(Maximum value allowed for the MS to request for non-DRX mode after packet transfermode).

If Non-DRX feature is enabled it has an influence on following parameters settings:

BS_AG_BLKS_RES, BS_PA_MFRMS, T_PDA, T_PUA, T_GPRS_assign_AGCH

T_GPRS_assign_AGCH parameter can be found in the memoMND/TD/SYT/EBR/0342.2001. In B7, the default value is set to 0.7 s

9.5 GPRS POWER CONTROL

In B7 GPRS power control is only implemented on the UL in an open loopconfiguration, which is described in the 05.08 GSM recommendations.

For GPRS rollouts it is recommended to disable the UL PC by setting

=0 and TNX =0

The reasons why GPRS UL PC shall be disabled:

MS controlled open loop PC is not working reliably (MS software implementation)

Field tests show a better throughput performance since the acknowledge messageis sent in UL with full power

It is possible to deactivate GPRS UL power control (CH=0 and =0) and to let GSMUL power control activated (EN_MS_PC=enabled, default), different Power Controlparameters for GSM and GPRS

If TMA (Tower Mounted Amplifier) is used and UL GPRS PC is disabled on a site thanbetter throughput in UL is expected. See QoS impacts of TMA in [6] and [7].

Fast Downlink TBF re-establishment process


Non-DRX feature benefits


Compatibility of GSM and GPRSUL Power control

Remark

Increase UL GPRS throughput


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APPENDIX A GSM NETWORK ENHANCEMENT FEATURES AND GPRS

A.1 Frequency Hopping and GPRS

Generally Frequency Hopping (FH) leads to network interference averaging. Thus calls

having good quality will get worse and bad calls will be improved, if frequencyhopping is used. This is valid for GSM and similar for GPRS:

CS1 is used in bad conditions, thus it will be improved if FH is introduced

CS4 is used in very good conditions, which are more seldom in a hoppingnetwork. Thus CS4 will perform less good and will be used more seldom

The overall gain of CS1-CS3 will depend on the C/I situation before and after FH

In B7, CS adaptation parameters can be tuned more optimistic in respect tothroughput and Coding Scheme if FH is used, see chapter 9.2.6:

CS_QUAL_XX_1_2_FH_Z > CS_QUAL_XX_1_2_NFH_Z

FH= Frequency Hopping and NFH= Non Frequency Hopping

A.1.1 GPRS load and GPRS performanceFollowing can be seen in simulation results:

The higher the GSM+GPRS load is, the higher is the probability for interference and sofor decreased GPRS performance.

As GPRS performance is mainly radio quality (C/I) dependent increased interferencelevel in the cell will reduce the GPRS throughput performance.

To reduce the load in the network/cell following GSM activities can be started:

Adding more resources, frequencies

Make smaller cell sizes (e.g. achieved by stronger tilt)

Do proper cell planning

A.2 -cell with GPRS

The main advantage of a -cell environment may be a better frequency re-usepossibility, thus better C/I value and higher throughput can be expected (especially forE-GPRS with higher C/I requirements than GPRS s). Following two steps is proposed forGPRS implementation:

If GPRS traffic is low, an introduction of GPRS in macro cell and -cell can be done.

Disadvantages:

Emergency capacity on macro cell layer reduced

Higher blocking probability on -cell layer for CS traffic

Solution:

Reduction of the maximum GPRS capacity of the -cell to 30-50% byparameter setting

Tuning of the GPRS user access handling (TBF and PDCH share)

If GPRS traffic increases a network densification must be done.

Hardware measures: TRX upgrade, -cell and macro cell densification, site design

Parameter measures: GPRS capacity and user access handling tuning

Basis measures: OMC-R Load measurements and GPRS customer behavior



Step 1: GPRS traffic is low

Step 2: Increasing GPRS traffic


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A.3 Dual Band with GPRS

In B7 the BCCH and the TRX with PDCH function work only in the same frequencyband

In a multiband BSS configuration there is a dedicated BCCH for each cell/frequencyband.

GPRS (PS) functionality can be configured in both bands

Class B and C MSs can make interband cell reselection during data transmission.

For this it is necessary to activate the GPRS service on each frequency band.

In a multiband cell the TRXs of one band are allocated to the outer zone and the TRXsof the other band to the inner zone. The BCCH is configured only in the outer zone.

The TRXs for GPRS (PS) traffic must be configured in the outer zone

Class B and C MSs will always be served by the outer zone GPRS TRXs, during PStraffic.

The GPRS MS does the GPRS cell reselection autonomously because supported networkcontrol order in B7 is NC0, see chapter 9.3. This brings the following limitations:

It is not possible to allocate resources of the second band of a multiband cellto the GPRS service in NC0.

The only way to allocate resources of both GSM 900 and DCS 1800 bandsto the GPRS service is to migrate the BCCH to the multiband BSC feature

Explanation:

Due to the fact that the path loss of both bands is not the same, and the BTSoutput power levels may also not be the same between the BCCH and thePDCH group of the second band, it is not ensured that the DCS 1800coverage is the same as the GSM 900 coverage.

In NC0 mode (autonomous cell reselection done by the mobile station), the

BSS does not get from mobile stations periodic measurement reports of theRXLEV of the BCCH of the serving cell.

It is not possible to allocate resources of the second frequency band at the downlinkTBF establishment time. Only during the downlink data transfer, the mobile stationreports the RXLEV of the BCCH of the serving cell (through the Packet DownlinkAck/nack). The only feasible strategy would be to allocate resources of the BCCHfrequency band at TBF establishment time, and then reassign resources of the secondband in case the reported measurements would guarantee the correct receipt of theinner zone by the mobile station.

However, this would lead to frequent TBF resources reallocations, with uncertain gainas the BSS does not know the volume of data to be transferred to the MS (e.g. with

WAP exchanges profile, a resources reallocation would only lead to a decrease ofthroughput and an increase of signaling traffic).

As the Alcatel BSS does only support uplink power control in open loop, it is notpossible to determine the path loss. As the inner zone coverage is not known (it may besmaller than the outer zone one), no band reselection can be decided.

In addition, if after the band reselection the MS leaves the inner zone but is still in theouter zone, a new band reselection shall be triggered by the network towards the outerzone before a cell reselection is triggered in the MS!

A.4 Concentric Cells with GPRS

In B7, the TRX for PS traffic must be configured in the outer zone of the concentric cell,

no GPRS cell-reselection to inner zone possible, see also appendix A.3 multiband cell.

Multiband BSS approach

Multiband cell approach

Limitations

Downlink

Uplink


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So total needed PDCH is 5 PDCH TS per cell= 49.6 kbit/s / 10 kbit/s

APPENDIX B GPRS TRAFFIC ANALYSIS CALCULATION METHODS

B.1 Straight Forward calculation for GPRS Traffic

GPRS users (Packet Switched Service)=600

WAP users: 60

WEB users: 180

SMS users: 360

WAP data size per user 12KB

WEB data size per user 40KB

SMS data size per user 40KB

WAP: 12KB*8bit/3600s*60 user= 1.6 kbit/s

WEB: 40KB*8bit/3600s*180 user= 16 kbit/s

SMS: 40KB*8bit/3600s*360 user= 32 kbit/sSum of data rate for all services: 49.6 kbit/s

Expected transfer rate per Timeslot (PDCH)= 10 kbit/s in good radio conditions

B.2 Erlang C GPRS traffic calculation

GPRS users (Packet Switched Service)=600

WAP users: 60

WEB users: 180SMS users: 360

WAP data size per user 12KB (page size 0.3 KByte/s)

WEB data size per user 40KB (page size 2 KByte/s)

SMS data size per user 40KB (page size 2 KByte/s)

WAP service: bit rate = 5 kbit/s for 90% Quantile and 2s queue delay

WEB service: bit rate = 30 kbit/s for 90% Quantile and 2s queue delay

SMS service: bit rate = 30 kbit/s for 90% Quantile and 2s queue delay

The following results calculation can be done with an Erlang C tool. Here the Erlang C

calculation part of the TRAFFIC TOOL BETA version 1.0 from ND [2] was used. Theresults are listed for each service (in this example her for WAP, WEB and SMS)

WAP:

Figure 13: Number of resources for WAP service with Erlang C calculation

Number of GPRS Users per cell

Service data size per user inbusy hour (per 3600s)

Needed transfer rate per servicefor all users

Total number of needed PDCH

Number of GPRS Users

Service data size per user inbusy hour

QoS per service

Number of needed PDCH per

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6 PDCH TS per cell is needed in total to

co e with GPRS traffic er cell

So in the sum for all services10 PDCH TSper cell are needed to offer the needed QoSfor the services in GPRS

WEB:

E R L A N G C

Volume@BH

Pagesize(Kbytes)

Subscribers

Queuedelay(s)

Quantile

Bitrate

4 0 2 1 8 0 2 s 9 0 . 0 % 3 0

1 0 . 5 3 3 3 1 .8 7 5 0

PDCH=

RO=

MU=

Figure 14: Number of resources for WEB service with Erlang C calculation

SMS:

E R L A N G C

Volume

@BH

Pagesize

(Kbytes)

Subscr

ibers

Qu

eue

de

lay

(s)

Qu

an

tile

Bit

rate

4 0 2 3 6 0 2 s 9 0 .0 % 3 0

2 1 .0 6 6 7 1 .8 7 5 0

PDCH=

RO=

MU=

Figure 15: Number of resources for SMS service with Erlang C calculation

Assumption: Expected rate per TS of 10 kbit/s

For the WAP service 1 resource of 5 kbit/s is needed = 1 PDCH TS

For the WEB service 1 resource of 30 kbit/s is needed = 3 PDCH TS

For the WEB service 2 resources of 30 kbit/s is needed = 6 PDCH TS

B.3 TRAFFIC TOOL BETA version 1.0

For the same conditions as in Appendix B.1 and B.2 the results of the traffic tool is:

Used settings in the traffic tool:

No activation of: Combined mode, DL Delayed TBF Release and MPDCH

Call Mix Reference used is: Alcatel B7 reference

Total number of needed PDCH


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