16.2-Bsspar- Gprs and Egprs (Edge)

BSSPAR

BSSPAR- GPRS & EGPRS (EDGE)Training Document

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BSSPAR- GPRS & EGPRS (EDGE)

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This document is intended for the use of Nokia Networks' customers only for the purposes of the agreement under which the document is submitted, and no part of it may be reproduced or transmitted in any form or means without the prior written permission of Nokia Networks. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation.

The information or statements given in this document concerning the suitability, capacity, or performance of the mentioned hardware or software products cannot be considered binding but shall be defined in the agreement made between Nokia Networks and the customer. However, Nokia Networks has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. Nokia Networks will, if necessary, explain issues which may not be covered by the document.

Nokia Networks' liability for any errors in the document is limited to the documentary correction of errors. Nokia Networks WILL NOT BE RESPONSIBLE IN ANY EVENT FOR ERRORS IN THIS DOCUMENT OR FOR ANY DAMAGES, INCIDENTAL OR CONSEQUENTIAL (INCLUDING MONETARY LOSSES), that might arise from the use of this document or the information in it.

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Copyright © Nokia Oyj 2003. All rights reserved.

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Contents

1 Module Objectives........................................................4

2 Introduction...................................................................5

3 GPRS Channels.............................................................73.1 Support of PCCCH/PBCCH, C31, C32...........................8

4 Priority Class based QoS...........................................10

5 EGPRS Parameters.....................................................135.1 EGPRS Link Adaptation parameters............................13

6 Dynamic A-bis Pool Creation Parameters................15

7 Nokia Smart Radio Concept for EDGE......................17

8 Key Learning Points...................................................18

9 Review Questions.......................................................21

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1 Module ObjectivesAt the end of the module, the participant should be able to:

List the parameters that are used for (E)GPRS radio timeslot (RTSL) classification

Explain the purpose of the C31 and C32 criteria in (E)GPRS

Discuss the implementation of priority class based QoS in (E)GPRS

Describe the Dynamic A-bis allocation in BSS10.5

State the purpose of the Nokia Smart Radio Concept (SRC)

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2 Introduction GSM timeslots are used for circuit switched (CS) traffic and assigned by the GSM network. In GPRS, timeslots for packet switched (PS) traffic are assigned by the Packet Control Unit (PCU) in the BSC.

GPRS is enabled in a BTS using GprsEnabled(GENA)(BTS)(Yes/No). This parameter defines whether the GPRS capability is enabled in the BTS during normal operation of the cell.

One question that arises is how many TS are to be reserved for each type of service. Circuit switched traffic has priority over packet switched traffic. However, when there are idle GSM timeslots, one would like to transmit as much PS traffic on them.

GPRS Timeslots are classified into dedicated, default, and additional TSL. Dedicated TSL are timeslots that are exclusively reserved for GPRS traffic and no CS traffic can be transmitted on them. If congestion occurs for circuit switched traffic, then only dedicated GPRS traffic channels can carry PS traffic. Default TSLs are by default, for GPRS traffic channels that can be dynamically configured to handle CS load if needed. The default TSL are always switched to the PCU when allowed by the CS traffic load. Additional TSL by default may carry CS traffic, but can be dynamically configured into GPRS timeslots when required. During peak GPRS traffic periods, additional channels are switched to GPRS use, but only if the CS traffic load permits that to occur.

All full rate or dual rate traffic channels are capable of carrying GPRS traffic channels. The operator can set the following:

GPRS capacity cell by cell and TRX by TRX

Amount of Dedicated TSL

Amount of Default TSL

Amount of additional TSL

BCCH TRX or non-BCCH TRX is preferred for GPRS

The boundary between CS and PS territory can move dynamically as shown below.

Figure 1. GPRS – GSM Boundary

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The following parameters are used for setting GPRS dedicated and default capacities:

defaultGPRScapacity (CDEF)(BTS)(0..100%) parameter defines the default packet-switched channels in a cell. It is used to set the percentage of available RTSL for GPRS capacity. The capacity is given as a percentage of the total capacity of the cell. Any percentage is rounded up to the closest integer RTSL. A setting of 0.01% means 1 RTSL, and 20% for a 1 TRX cell also means 1 RTSL. The MML default is 1%.

dedicatedGPRScapacity (CDED)(BTS)(0..100%) is used to set the dedicated percentage of packet-switched RTSL for GPRS capacity. The capacity is given as a percentage of the total capacity of the cell. The default is 0%.

In general, DedicateGPRScapacity < DefaultGPRScapacity

terrUpdateGuardTimeGPRS (GTUGT)(BSC)(1..255) is used to set the timer which elapses between two adjacent territory updates. The MML default is 5.

Idle

Standby

Ready

PacketTX/RXSTANDBY

Timer Expiry

GPRSAttach/ Detach

READYTimer Expiry

MS location known to RA level. MS is capableof being paged data

MS location not known. Subscriber is notreachable by the GPRS NW.

MS location known to cell level.MS is transmitting or has just been transmitting.

Figure 2. GPRS Mobility Management States

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3 GPRS ChannelsGPRS introduces several new logical channels to the GSM air interface. There are no dedicated signalling channels as in GSM. The Packet Data Channels (PDCH) are used for data and signalling.

PBCCH The Packet Broadcast Control Channel is a downlink only channel for broadcasting packet data (GPRS) specific system information messages to all GPRS enabled MS in a cell. If the PBCCH is not allocated, the packet data specific SI is broadcast on the BCCH.

PCCCH The Packet Common Control Channel (PCCCH) consists of logical channels used for common control signalling for packet data. There are four types of PCCCH: PRACH, PAGCH, PPCH and PNCH.

PRACH The Packet Random Access Channel is an uplink only channel, which the MSs use for uplink traffic channel request and for obtaining the timing advance. The normal GSM RACH can also be used for this, in case there is no PCCCH allocated in the cell.

PPCH The Packet Paging Channel is a downlink only paging channel used to page the MS prior to downlink packet transfer. The PPCH can be used for paging of both CS & PS data services. The normal GSM PCH can be used for GPRS in case there is no PCCCH allocated in the cell.

PAGCH The Packet Access Grant Channel is a downlink only channel used for resource assignment during the packet transfer establishment phase. The normal GSM AGCH can be used in case there is no PCCCH allocated in the cell.

PNCH The Packet Notification Channel (only in GPRS Phase2) is a downlink only channel used for the PTM-M notifications to a group of MSs before PTM-M packet transfer.

PDTCH The Packet Data Traffic Channel is reserved for GPRS packet data transfer. A PDTCH corresponds to the resource allocated to a single MS on one physical channel for user data transmission. In multislot operation, one MS may use multiple PDTCHs in parallel for individual packet transfer. PDTCH are uni-directional as opposed to TCH in GSM.

PACCH The Packet Associated Control Channel (bi-directional) is a signalling channel dedicated for a certain MS. The signalling information could include acknowledgements, power control, resource assignments or reassignment messages.

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PTCCH The Packet Timing advance Control Channel is used in the uplink direction for the transmission of random access bursts to estimate

the timing advance for one mobile. In the downlink direction one PTCCH is used to transmit timing advance information to several MSs. PTCCH information is transmitted in positions 12 and 38 of the 52 multiframe structure.

Figure 3. GPRS Logical Channels

3.1 Support of PCCCH, PBCCH, C31, C32

This feature will bring dedicated CCCH capacity for (E)GPRS services using PCCCH. It is selected using the following:

preferBCCHfreqGPRS(BFG)(BTS)(Yes/No) is used to set that the BCCH TRX is to be used for GPRS channel allocation. By default, this value is set to No.

The new cell re-selection criteria C31 and C32 are provided as a complement to the current GSM cell re-selection criteria. C31/C32 provide a more general tool, which makes cell planning for GPRS similar to existing planning in GSM. C31 is a signal strength criterion used to decide whether prioritised cell re-selection shall be used. For cells that fulfil the C31 criterion, the cell with highest priority class shall be selected. If more than one cell has the highest priority, the one of those with the highest C32 value shall be selected. If no cell fulfils the C31 criterion, the one among all cells with the highest C32 value shall be selected.

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PBCCH broadcasts packet data specific System Information (for example C31 and C32 cell selection criteria). If PBCCH is not allocated, the packet data specific system information is broadcast on BCCH, and existing C1/C2 are used.

Note: PCCCH/PBCCH are mapped to own timeslot. It should be configured on the same TRX as BCCH in the case of Multi-band cell.

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4 Priority Class based QoS At a system level, the concept of ‘Priority Class’ is introduced. This is based on combinations of GPRS Delay class and GPRS Precedence class values. Packets will be evenly scattered within (E)GPRS territory between different timeslots. After this, packets having higher ‘Priority’ are send before those packets having lower ‘Priority’.

AGCHAvailability

AvailableCapacity

TBF Session Success

PDTCHAvailability

EitherPCU

orTRX

Data Connection Success

ReadyState

sendRACH

EstablishImmediateAssignment

GetPDCH

RequestedTSL

toAllocated

TBFSession

Releasephase

Figure 4. Establishing a TBF and sending Data - Uplink

PagingSuccess RateAvailability

AvailableCapacity

TBF Session Success

UplinkTBF

Establishment

Data Connection Success

InStandby

PagingFrom

Network

Establish

UplinkTBF

ImmediateAssignment

RequestedTSL to

Allocated

TBFSession

ReleasePhase

Figure 5. Establishing a TBF and sending Data - Downlink

Currently all TBFs (GPRS calls) have same priority. All users and all applications get same service level. The needs from different applications differ and mechanisms to have separate service levels are required. GSM specifications define QoS functionality, which gives a possibility to differentiate TBFs by delay, throughput and priority. Priority Based Scheduling is introduced as the first step towards QoS. With Priority Based Scheduling operator can give users different priorities. Higher priority users will get better service than lower priority users. There will be no extra blocking to any user, only the experienced service quality changes.

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The scheduling algorithm gives each link a so-called latest service time, before which the connection should get a chance to use the radio resource. After the link has used the radio resource it is given a new latest service time, which is the current time plus a predefined step. The connection that has the smallest latest service time gets to use the radio resource. Periodically the scheduling algorithm comes and checks on the queue. In Nokia GRPS Release 1(BSS9), these steps are set to the same constant value for all TBFs. This in effect produces a round robin like queuing system.

The new algorithm is priority based. It selects the best possible timeslot within territory and then prioritises the TBFs residing in that timeslot so that the TBF with the highest priority gets the most air interface. As the solution does not affect the allocation process, the number of customers served stays constant when compared to Nokia GPRS release 1.

Each timeslot has a queue in which the TBFs wait for their turn to use the radio air interface. After the TBF has used its air interface time, it increases its latest service time to the current time plus it's scheduling step size. The use of the current time is explained by new TBFs coming in to the system, all TBFs must start from the same situation.

The algorithm has a direct impact on the scheduling algorithm. The sizes of the scheduling steps have to be set so that they reflect the handing out of radio resources, because the time a certain link has control of the radio resource is decided by the scheduling algorithm. Each service class is given fair amounts of radio time. The only exception being best effort customers, who are given a small share of the radio interface. Priorities are implemented by giving different scheduling step sizes for different QoS classes. Scheduling step sizes are operator adjustable. There are 4 QoS classes for uplink, and 3 QoS classes for downlink.

Table below gives some suggested values for the step sizes. The actual parameter values will be operator adjustable and Nokia suggested values will be presented based on simulations.

QoS class "gold" "silver" "bronze" Best effort

Step size 3 6 9 12

Table 1. Set of scheduling step sizes

This algorithm provides priorities between TBFs in the same timeslot so that the TBFs that have the same QoS get an equal share of airtime. However equal air time does not provide equal data rates for the TBFs in the same timeslot, it only guarantees that inside a QoS group the air time is divided equally and that a higher QoS class gets more air time.

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Figure 6. Example of transmission turns

Mobile specific flow control is part of the QoS solution in the PCU. This feature works together with the SGSN to provide a steady data flow to the mobile from the network. It also is an effective countermeasure against buffer overflows in the PCU.

Priority Based Scheduling in BSC is standard feature and subscriber priority needs to be defined in HLR once this feature is taken into use.

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5 EGPRS ParametersThe following parameters are used in EGPRS (=EDGE + GPRS):

Base Transceiver Station Handling parameters (PBTHAN):

EgprsEnabled (EGENA)(BTS)(Y/N)(N) is used to enable or disable EGPRS on BTS level. All TRXs of the BTS have to be EDGE capable.

maxGPRScapacity(CMAX)(BTS)(1..100%)(100%): with this parameter, you define the maximum number of packet switched channels in a BTS.

gprsNonBCCHRxlevUpper (GPU)(BTS)(-110 .. -47 dBm)(-95 dBm) sets the minimum power level the MS has to receive to allocate resources from the BTS.

gprsNonBCCHRxlevLower (GPL)(BTS)(-110..-47 dBm)(-100 dBm): With this parameter, you define the threshold when reallocation to better BTS in SEG must be done. BTSs preferred with direct GPRS access threshold are selected.

directGPRSaccessBts (DIRE)(BTS)(-10 .. 10 dBm)(0 dBm): With this parameter you define which BTSs may be used for GPRS or EGPRS without signal level measurements. This parameter defines the signal level compared to non BCCH layer offset. When the value of this parameter is higher than the value of the parameter non BCCH layer offset the direct GPRS access to non BCCH layer BTS is applied. This is used in initial channel allocation and reallocation.

Power Control Handling parameter (PORTER):

BepPeriod (BEP)(BTS)(1,2,3,4,5,7,10,12,15,20,25)(10) parameter defines the bit error probability filter averaging period for EGPRS channel quality measurements

5.1 EGPRS Link Adaptation parameters

The following parameters are used in EGPRS link adaptation.

initMcsAckMode(MCA)(SEG)(1..9)(9) parameter indicates the Modulation and Coding Scheme (MCS) used in the beginning of a TBF for acknowledged mode

initMcsUnackMode(MCU)(SEG)(1..9)(6) parameter indicates the Modulation and Coding Scheme used in the beginning of a TBF for unacknowledged mode

maxBlerAckMode (BLA)(SEG)(10..100%)(90%) parameter is used to indicate maximum block error rate(BLER) of first transmission in acknowledged mode

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maxBlerUnackMode (BLU)(SEG)(1..100%)(10%) parameter sets the maximum BLER in unacknowledged mode

meanBepOffsetGMSK (MBG)(SEG)(-31 ..31)(0) parameter is used to adjust the MCS and modulation preferences. This is the offset added to reported GMSK mean BEP values before BEP table lookups. The value applies to both uplink and downlink directions.

meanBepOffset8PSK (MBP)(SEG)(-31 ..31)(0): With this parameter you can adjust the MCS and modulation preferences. This is the offset added to reported 8PSK mean BEP values before BEP table lookups. The value applies to both uplink and downlink directions.

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6 Dynamic A-bis Pool Creation Parameters

Dynamic A-bis allocation in BSS10.5 is a solution for higher data rates of EGPRS to ensure cost efficiency and flexible A-bis transmission capacity addition. The Dynamic A-bis functionality allocates A-bis transmission capacity to cells when needed instead of reserving full fixed transmission link per TRX.

As data rates per radio timeslot can vary between 8.8 and 59.2 kbps, traditional static A-bis allocation does not use transmission resources efficiently. The Dynamic A-bis feature uses existing A-bis more efficiently by splitting PCMs into permanent timeslots for signalling and voice or data and a dynamic pool for data. The pool can be shared by a number of transceivers. The Dynamic A-bis transmission solution saves up to 70% in the A-bis transmission expansion cost as it allows A-bis dimensioning to be performed near to the average data rates instead of peak rates. This also applies to the number of 2M BSC interfaces needed.

Dynamic A-bis is implemented as a software feature. Quality of service is improved by the Dynamic A-bis method, which uses allocation of circuit switched connections under real time centralised control. The implementation of shared transmission channel connection pools is supported by Nokia cellular transmission cross connection products and made easy with the Nokia NetAct transmission network planning tool.

Figure 7. Dynamic A-bis

Implementation of A-bis channel mapping is arranged so that traditional (not EDGE) TRXs are connected normally to BSC, with a 16 kbps point-to-point link from the TCH to the BSC. EDGE TRXs are configured slightly differently

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as the basic capacity is reserved for signalling (TRXSIG, BCFSIG). The BSC allocates A-bis capacity for calls (voice or data) from the pool when required. The capacity for calls can be reserved in 16kbps blocks. For every EDGE TRX, there is a fixed 16 kbps allocation for TRXSIG and in addition, capacity needed for calls is reserved from the Dynamic A-bis Pool. This Dynamic A-bis pool can be common for many EDGE TRXs located at various sites.

Maximum number of TRXs per Dynamic A-bis pool is 32 due to signalling requirements of BCSU unit.

Interworking with other Nokia features

ISDN A-bis

ISDN A-bis and Dynamic A-bis allocation can not be used together.

Optimised A-bis allocation

Optimised A-bis allocation becomes unnecessary, because the traffic channels are allocated on a call basis and since signalling links are fixedly allocated.

Satellite A-bis

Satellite A-bis connections can be dynamically allocated.

GPRS

GPRS territory method and EGPRS use the dynamic A-bis.

Compatibility with base stations

BSS10.5 solution for the Dynamic A-bis is compatible with Nokia MetroSite and UltraSite EDGE base station EDGE TRXs.

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7 Nokia Smart Radio Concept for EDGE Nokia Smart Radio Concept (SRC) is an important new feature for getting the maximum EDGE benefit, first phase supported by Nokia UltraSite EDGE base station with BSS10 hardware and software.

SRC is a novel feature that will enhance the radio performance of the BTS, both in EDGE and GSM mode. The Nokia SRC includes a combination of diversity solutions applied in both uplink and downlink directions. The Nokia SRC for EDGE is used to improve radio link performance to ensure maximum coverage, improved data capacity and high service quality. For utilising the Nokia SRC, EDGE capable equipment is required.

4 way uplink diversity and Interference Rejection Combining, IRC

In the BSS10 the uplink performance (BTS reception) is enhanced with the combination of Interference Rejection Combining via 4-way diversity reception of the BTS and sensitivity optimised high-gain Nokia UltraSite Masthead Amplifiers (UltraSite MHA introduced already in BSS9).

IRC tries to null correlated noise received by both antennas.

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8 Key Learning Points GprsEnabled(GENA)(BTS)(Yes/No) is used to define whether GPRS

capability is enabled in the BTS during normal operation of a cell.

DefaultGPRScapacity (CDEF)(BTS)(0…100%) parameter defines the default packet switched channels in a cell. It is used to set the percentage of available TSL for GPRS capacity.

DedicateGPRScapacity (CDED)(BTS)(0…100%) is used to set the dedicated percentage of packet switched TSL for GPRS capacity.

In general, DedicateGPRScapacity < DefaultGPRScapacity

TerrUpdateGuardTimeGPRS (GTUGT)(BSC)(0 … 255) is used to set the timer between two adjacent territory updates. The MML default is 5.

PreferBCCHfreqGPRS(BFG)(BTS)(Yes/No) is used to set that the BCCH TRX is to be used for GPRS channel allocation. By default, this value is set to No.

The C31 and C32 feature will bring dedicated CCCH capacity for GPRS and EGPRS services.

PCCCH comprises logical channels for packet common control signalling and consists of PRACH PPCH, PPCH, PAGCH, and PBCCH.

New cell re-selection criteria C31 and C32 complement current GSM cell re-selection criteria C1 and C2.

C31 is a GPRS signal strength criterion for prioritised cell re-selection. If many cells satisfy C31, the cell with highest priority class is selected.

C32 is used to specify cell priority. If more than one cell has the highest priority in C31 or if no cell satisfies C31, the cell with highest C32 value is selected.

If PBCCH is not allocated, the packet data specific system information is broadcast on BCCH, and existing cell reselection GSM C1/C2 are used.

Priority Class based QoS is based on GPRS Delay class and GPRS Precedence class values. Initially packets are distributed within (E)GPRS timeslots. Then, packets having higher priority are sent before those having lower ‘Priority’.

Priority based scheduling allows packets to be transmitted in order of priority. Scheduling algorithm sets each TBF a latest service time during which user packets are transmitted. The connection with smallest service time uses radio resource first. Each timeslot has a queue in which TBFs wait for their turn to use the timeslot. When user has transmitted its packets, the service is stepped: latest service time = current time + predefined step.

In Nokia GRPS Release 1(BSS9), steps are set to a constant value for all TBFs resulting in a round robin queuing system, i.e. all TBFs have same priority.

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The sizes of scheduling steps have to be set so that they reflect the handing out of radio resources. Priorities are implemented by giving different scheduling step sizes for different QoS classes. Scheduling step sizes are operator adjustable. There are 4 QoS classes for uplink, and 3 QoS classes for downlink.

GPRS and EGPRS data rates per RTSL can vary between 8.8 and 59.2 kbps.

Static A-bis allocation reserves full fixed transmission link per TRX and hence does not use transmission resources efficiently.

Dynamic A-bis allocation in BSS10.5 is a solution, which dynamically allocates A-bis transmission capacity to (E)GPRS cells when needed. Its principles are

Existing A-bis PCMs are split into permanent timeslots for signalling and voice or data and a dynamic pool for data.

The pool can be shared by a number of transceivers.

A-bis dimensioning uses average data rates instead of peak rates.

It is implemented as a software feature.

Implementation of A-bis channel mapping is arranged so that

Traditional (non EDGE) TRXs are connected to BSC, with a 16 kbps point-to-point link from the TCH to the BSC.

EDGE TRXs are configured such that basic capacity is reserved for signalling (TRXSIG, BCFSIG).

BSC allocates A-bis capacity for calls (voice or data) from the pool when required. The capacity for calls can be reserved in 16kbps blocks.

For every EDGE TRX, there is a fixed 16 kbps allocation for TRXSIG and in addition, capacity needed for calls is reserved from the Dynamic A-bis Pool. This Dynamic A-bis pool can be common for many EDGE TRXs located at various sites.

Maximum number of TRXs per Dynamic A-bis pool is 32 due to signalling requirements of BCSU unit.

Nokia Smart Radio Concept (SRC) is an important new feature for getting the maximum EDGE benefit. The first phase is supported by Nokia UltraSite EDGE base station with BSS10 hardware and software.

The Nokia SRC includes a combination of diversity solutions applied in both uplink and downlink directions.

The Nokia SRC for EDGE is used to improve radio link performance to ensure maximum coverage, improved data capacity and high service quality.

In the BSS10 the uplink performance (BTS reception) is enhanced with the combination of Interference Rejection Combining via 4-way diversity reception of the BTS and sensitivity optimised high-gain Nokia UltraSite Masthead Amplifiers (UltraSite MHA introduced already in BSS9).

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1.1.1 SGSN parametersIMEI Check Mode (ICHM) ONAuthentication Mode (AUM) ONPTMSI Signature Mode (PSMO) ONCiphering Mode in Use (CIPINUSE) ONCiphering Mode After System Reset (CIP) ON

Ready State Timer (RDY) 000-44 mm-sMS Reachable Timer (MSRT) 060-00 mm-sPeriodic RA Update Timer (PRAU) 054-00 mm-sVLR Periodic Cleaning Start Time (CTIM) 00:00 hh:mmDetached Subscriber Storage Time (STT) 001-00 ddd-hhUtilisation Rate Dependent Cleaning (UDC) 80 %Utilisation Rate Zero Limit (UDL) 100 %Forced to Standby (FTS) Y

RA Paging Repetition (RPR) 3.5 sRA Paging Area (RPA) 2SGSN Paging Area (SPA) 0

DNS Check, if round-robin is in use. Bind version 8.1.2 should be used in Rel.1 Bind version 8.2.4 should be used in Rel.2

GGSN Check GTP tunneling towards Gn Check tunneling to Gi (L2TP, IPinIP, GRE, IPsec) Routing protocol in Gn Routing protocol in Gi Access list Check LIE (query to LIC from GGSN for every PDP

context?)

Figure 8. Parameter Verification

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9 Review Questions Q1. Which of the following parameter(s) is/are used to define RTSL that are permanently allocated for packet switched data transmission

a) GprsEnabled(GENA)(BTS)(Yes/No)

b) DefaultGPRScapacity (CDEF)(BTS)(0…100%)

c) DedicateGPRScapacity (CDED)(BTS)(0…100%).

d) TerrUpdateGuardTimeGPRS (GTUGT)(BSC)(0 … 255)

e) PreferBCCHfreqGPRS(BFG)(BTS)(Yes/No)

f) All of the above.

Q2. Which of the following is true about C31 and C32?

a) It brings dedicated CCCH capacity for GPRS and EGPRS services.

b) It complements current GSM cell re-selection criteria C1 and C2 and is only used when PBCCH is allocated.

c) C31 is a GPRS signal strength criterion for prioritised cell re-selection.

d) If many cells satisfy C31, the cell with highest priority class is selected.

e) C32 is used to specify cell priority.

f) All of the above.

Q3. When is C32 used?

a) If many cells satisfy C31 criterion and only one cell has highest priority.

b) If many cells satisfy C31 and more than one cell has the highest priority.

c) If no cell satisfies C31 but cell reselection has to be performed.

d) Criteria (a), (b) and (c)

e) Criteria (b) and (c)

Q4. How is priority class based QoS used in GPRS and EGPRS?

a) It is used in Nokia GRPS Release 1(BSS9) to provide 5 different QoS for users.

b) It enables priority usage of PBCCH and BCCH.

c) It gives priority to users packets on a first come first serve basis.

d) It allows packets to be transmitted in order of priority based on GPRS Delay class and GPRS Precedence class values.

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e) All of the above.

Q5. Which of the following about priority class scheduling algorithm is FALSE?

a) Sets TBF's a latest service time during which user packets are transmitted.

b) The connection with largest service time uses radio resource first.

c) Each timeslot has a queue in which TBFs wait for their turn to use the slot.

d) When user has transmitted its packets, the service is stepped latest service time = current time + predefined step.

Q6. How many QoS classes are provided in Nokia BSS10.5?

a) 4 QoS classes for uplink, and 4 QoS classes for downlink.

b) 3 QoS classes for uplink, and 3 QoS classes for downlink.

c) 4 QoS classes for uplink, and 3 QoS classes for downlink.

d) 3 QoS classes for uplink, and 4 QoS classes for downlink.

e) None of the above.

Q7. What is difference between static and dynamic A-bis allocation?

a) (E) GPRS data rates per radio TS can vary between 8.8 and 59.2 kbps.

b) Static A-bis dynamically allocates full fixed transmission link per TRX.

c) Dynamic allocation does not use transmission resources efficiently.

d) Dynamic A-bis allocates A-bis transmission capacity to (E)GPRS cells when needed rather fixed allocations.

e) None of the above

Q8. What are the principles of Dynamic A-bis Allocation?

a) Existing A-bis PCMs are split into permanent timeslots for signalling and voice or data and a dynamic pool for data.

b) A pool of PCM timeslots can be shared by a number of transceivers.

c) A-bis dimensioning uses average data rates instead of peak rates.

d) It is implemented as a software feature in Nokia BSS10.5.

e) All of the above.

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