amr planning & implementation

GSM/EDGE BSS network planningand implementation for AMR

dn02247378Issue 1-0 en

# Nokia CorporationNokia Proprietary and Confidential

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GSM_EDGE_BSS10.5Nokia GSM/EDGE BSS10.5 SystemDocumentation Set

2 (38) # Nokia CorporationNokia Proprietary and Confidential


GSM/EDGE BSS network planning and implementation for AMR

Contents

Contents 3

1 Overview of Adaptive Multi Rate Codec, AMR 51.1 Link adaptation 101.2 Channel allocation 121.3 Requirements for AMR activation in Nokia networks 131.4 AMR parameters 14

2 AMR compatibility 23

3 Overview of planning AMR 27

4 Activating AMR in MSC 29

5 Activating AMR in BSC 33

6 Deactivating AMR 37



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Contents

1 Overview of Adaptive Multi Rate Codec,AMR

The Adaptive Multi Rate (AMR) codec, which was standardised for GSM during1998-1999, adapts its bit rate allocation between speech and channel coding,thereby optimising speech quality in various radio channel conditions. Thisprovides the next step in the improvement of speech quality in GSM after theintroduction of the Enhanced Full Rate (EFR) codec in 1996, which was the firstcodec to provide wireline speech quality. The new AMR codec brings furtherquality enhancements, especially in terms of high error robustness in the full ratechannel. It also provides the first codec with quality comparable to wireline forthe half rate channel in good channel conditions. All previous GSM codecsoperate with fixed partitioning between speech and channel coding (errorprotection) bit rates. These bit rates have been chosen as compromises betweenperformance in error-free and high-error channels. The AMR codec operates ineither the GSM full or half rate channel and selects the optimum bit rate trade-offbetween speech and channel coding, according to the channel quality, to deliverthe best possible overall speech quality. To achieve overall good speech quality,the quality degradation caused by speech coding and the errors engendered by thetransmission channel have to be carefully balanced. The benefits of AMR areseen when AMR capable phones come to the market.

AMR (Adaptive Multirate Codec) is a technology that enables operatorssmoothly and cost-efficiently to add voice capacity in their networks. In theNokia AMR solution, this requires only a software upgrade. AMR is one of thevoice capacity enhancement technologies (the others are: half rate, frequencyhopping, intelligent frequency hopping, further development of handoveralgorithm).

AMR consists of 8 different speech codec modes (bit rates of 12.2, 10.2, 7.95,7.4, 6.7, 5.9, 5.15 and 4.75 kbit/s) with total of 14 channel codec modes (seeTable Channel and speech codec modes available for AMR). All the speechcodecs are defined for the full rate channel, while the six lowest ones are definedfor the half rate channel. The net bit rate is 0.10 kbit/s (in-band channel). Thechannel coding bit rate (in-band) is 0.30 kbit/s.



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Overview of Adaptive Multi Rate Codec, AMR

Table 1. Channel and speech codec modes available for AMR.

Channelmode

Channelcodec

mode

Source codingbit rate, speech

Channelcoding bitrate, speech

TCH/FR CH0-FSCH1-FSCH2-FSCH3-FSCH4-FSCH5-FSCH6-FSCH7-FS

12.20kbit/s(GSMEFR)10.20 kbit/s7.95 kbit/s7.40 kbit/s (IS-641)6.70 kbit/s5.90 kbit/s5.15 kbit/s4.75 kbit/s

10.20 kbit/s12.20 kbit/s14.45 kbit/s15.00 kbit/s15.70 kbit/s16.50 kbit/s17.25 kbit/s17.65 kbit/s

TCH/HR CH8-HSCH9-HSCH10-HSCH11-HSCH12-HSCH13-HS

7.95 kbit/s(*)7.40 kbit/s (IS-641)6.70 kbit/s5.90 kbit/s5.15 kbit/s4.75 kbit/s

3.25 kbit/s3.80 kbit/s4.50 kbit/s5.30 kbit/s6.05 kbit/s6.45 kbit/s

(*) Requires 16 kbit/s TRAU. Therefore it is not seen as a feasible codec modeand is not supported by Nokia BSS10.

A mobile station must implement all the codec modes. However, the network cansupport any combination of them.

Each codec mode provides a different level of error protection through a differentdistribution between speech and channel coding.

The link adaptation process bears responsibility for measuring the channelquality. Depending on the quality and possible network constraints (for examplenetwork load), mode adaptation selects the optimal speech and channel codecs.The mobile station (MS) and the base transceiver station (BTS) both performchannel quality estimation for their own receive paths. Based on the channelquality measurements, the MS sends a Codec Mode Request (Mode requested tobe used in the downlink) to the BTS. This signalling is sent in-band, along with




the speech data. The codec mode in the uplink may be different from the one usedin downlink, but the channel mode (full rate or half rate) must be the same. Thein-band signalling has been designed to allow fast adaptation to rapid channelvariations.

Codec mode adaptation for AMR is based on received channel quality estimationin both MS and BTS, followed by a decision on the most appropriate speech andchannel codec mode to apply at a given time. In high-error conditions more bitsare used for error correction to obtain error robust coding, while in goodtransmission conditions a lower amount of bits are needed for sufficient errorprotection and more bits can therefore be allocated for the source coding.

An in-band signalling channel is defined for AMR that enables the MS and theBTS to exchange messages on applied or requested speech and channel codecmodes. The above mentioned selected speech codec mode is then sent by usingthe in-band signalling channel to the transmitting side, where it is applied for theother link. The BTS commands the MS to apply a particular speech codec modein the uplink by Codec Mode Command. The MS sends a Codec Mode Request(Mode requested to be used in the down-link) to the BTS. The BTS has an optionto override the MS's request. The codec mode in the up-link may be differentfrom the one used in the down-link, but the channel mode (full rate or half rate)must be the same.

Mobile station must support all speech codec modes, although only a set of up to4 speech codec modes is used during a call. BSC supports all of speech codecmodes, except 7.95 kbit/s on HR channel, and it has one default set for eachchannel mode. The default codec sets also include a default set of decisionthresholds and hysteresis. The initial codec mode and codec set with thresholdsand hysteresis are transferred between network elements and MS by using theexisting layer 3 signalling. Only a few add-ons are needed.

Benefits of AMR

GSM speech codecs (full rate - FR, half rate - HR and enhanced full rate - EFR)operate at a fixed coding rate. The channel protection (against errors) is alsoadded at a fixed rate. The coding rates are chosen as a compromise between bestclear channel performance and robustness to channel errors.

The AMR system exploits the implied performance compromises by adapting thespeech and channel coding rates according to the quality of the radio channel.This gives better and clearer channel quality and better robustness to errors.These benefits are realised regardless of whether operating in full rate or half ratechannels.



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Example 1.

Consider the situation where the mobile is in a zone of the cell border where youhave a bad C/I (for example 7dB). With EFR you have a degradation of thequality of the speech due to interference. With AMR, however, similar qualitycan be achieved with a reduced number of speech coded bits which allows morebits to be used for error protection and correction (see Figure ETSI Mean OpinionScore test results for current EFR/FR and AMR FR).

Together with quality improvements, the need to enhance capacity by allocatinghalf rate channels to some or all mobiles network is also recognised. The radioresource algorithm, enhanced to support AMR operation, allocates a half rate orfull rate channel according to channel quality and the traffic load on the cell inorder to obtain the best balance between quality and capacity.

Example 2.

Increase in capacity: in normal C/I condition two voice channels can use a singletimeslot in the case of Half rate coding (HR) with little or no compromise in voicequality compared to EFR (see Figure ETSI Mean Opinion Score test results forcurrent EFR/FR and AMR FR).

Optimal interworking with power control and handover algorithms together withenhanced quality measurements (FER Measurement feature) provides fullbenefits and interworking with prior Nokia capacity features including IntelligentFrequency Hopping (IFH).




Figure 1. ETSI Mean Opinion Score test results for current EFR/FR and AMRFR

1.0

2.0

3.0

4.0

5.0

No Errors 16 dB C/I 13 dB C/I 10 dB C/I 7 dB C/I 4 dB C/I

EFR

AMR FR

AMR Full Rate performance compared to

Full Rate EFR in Clean Speech

1.0

2.0

3.0

4.0

5.0

No Errors 19 dB C/I 16 dB C/I 13 dB C/I 10 dB C/I 7 dB C/I 4 dB C/I

FR

AMR HR

AMR Half Rate performance compared to

Full Rate in Clean Speech

MOS (Mean Opinion Score)

MOS (Mean Opinion Score)



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Related topics

. AMR compatibility

. Overview of planning AMR

1.1 Link adaptation

Link adaptation is the capacity of AMR feature to vary the codec used accordingto the link conditions. In this way both network, for up-link, and MS, for down-link, measure the radio conditions in each link and take decisions on which codecshould be applied to each way.

Two different types of link adaptation algorithms are defined: codec modeadaptation and channel mode adaptation. The channel mode adaptation algorithmdecides whether the speech can be handled by a full rate channel or by a half ratechannel according to the link conditions, whereas for the channel selected, thecodec mode adaptation algorithm decides which codec is the one that providesthe best speech quality for the current radio conditions. That is, as each codec hasdifferent channel protection and speech encoding performance, the idea of thecodec mode adaptation is to select the codec that provides the best speech qualityfor the radio conditions that the receivers are submitted to.

Codec mode adaptation

There are two link adaptation (LA) modes; the standardised fast LA and theNokia proprietary slow LA. Fast LA BTS allows in-band codec mode changes onevery other TCH frame, but in Nokia proprietary slow LA BTS allows in-bandcodec mode changes only on SACCH frame interval.

The choice of the LA mode is done on BSC basis with the parameterslowAmrLaEnabled: if it is set to N (default) it is used fast LA; if it is set to Yit used Nokia slow LA. With slow LA, BTS allows in-band codec mode changesonly on the SACCH frame interval of 480 ms and this option gives betterflexibility with HO and PC algorithms. During both LA modes, the BTS indicatesthe first and the last used codec during the last measurement interval and theaverage quality. The BTS commands the MS to apply a particular speech codecmode in the up-link, but the MS can only request the BTS to apply a particularspeech codec mode in the downlink, because the BTS has an option to overridethe MS's request (see Figure AMR Link Adaptation).

The codec mode bit rate, that is, the bit rate partitioning between the speech andchannel coding for a given channel mode, may be varied rapidly (see FigureExample of AMR Codec mode link adaptation). The codec mode can be switchedone up or one down at the time so that it is not possible to switch from the mode




12.2 kbit/s to 4.75 kbit/s when for example the modes 5.9 kbit/s and 7.4 kbit/s areincluded to the mode set. Also, it should be noted that codec changes do not takeplace immediately after the Codec Mode Command/Request is sent: there is adelay until a frame is received with the new codec.

Codec mode adaptation operates independently on the up-links and down-links. Itis transparent to the channel allocation and operates independently of it. Controldepends mainly on measurements of the quality of the respective links.

Channel mode adaptation

The channel mode (FR or HR) is switched to achieve the optimum balancebetween speech quality and capacity enhancements. The up-links and down-linksuse the same channel mode. The channel mode is selected by the network basedon measurements of the quality of the up-links and down-links.

Figure 2. AMR link adaptation

DL channelquality

UL codeccommand

DL codec

UL channel quality 16 or 8kbit/s

DLcodec

ULadaptation

MS BTS T

DLadaptation



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Figure 3. Example of AMR Codec mode link adaptation

1.2 Channel allocation

HR and EFR principles are applied with two exceptions.

The first exception is that an AMR call may be started in full rate channel in anew cell. It depends on the new parameter Initial AMR channel ratewhich has a default value Any Rate. This value means that the chosen channelrate is defined by taking into account the currently used information (ChannelType IE, resource situation on radio interface, circuit pool, current channel rate,HO parameters). The other option is AMR FR which means that full rate channel isallocated despite the values of the currently used information. If AMR FR codecis not present in the Channel Type element or it cannot be allocated (for exampleAMR FR set is disabled in the target cell), allocation continues with the currently

7.95 kbit/s

12.2 kbit/s

6.70 kbit/s

5.90 kbit/s

C/I EFR operation AMR mode

AMRC/I

30

25

20

15

10

5

00 5 10 15 20 25 30

Time[s]




used information. The parameter is valid in call setup (except FACCH call setup),internal inter cell HO and external HO. The reason behind this new parameter isthat quality may not be sufficient for HR AMR call setup (radio measurement isdone on SDCCH).

The second exception is that AMR capable TRXs are allocated first for AMRspeech call use and at the latest for other speech calls.

1.3 Requirements for AMR activation in Nokianetworks

BSC Capacity requirements

Maximum 512 TRXs, if RTSLs are configured as FR channels.

Maximum 256 TRXs, if RTSLs are configured as HR or DR channels.

Signalling requirements on Air and Abis interfaces

Performance of signalling channels such as SACCH and FACCH which arecarried by the same TSL, should be checked.

Introduction of AMR HR causes increased load in measurement reporting;therefore a 16 kbit/s LAP-D signalling link does not have enough capacity in allcases. When the TRX contains merely HR or DR TCH resources, the situationbecomes even worse if the SDCCHs have also been configured on the TRX.Therefore a 32 kbit/s LAP-D link should be introduced to support the telecomsignalling.

Configuration requirements

The new circuit pool (pool 23) is needed in A interface configuration. AMRfeature needs to be activated first and Abis parameters need to be set on Abisinterface.

Equipment requirements

See AMR compatibility.



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1.4 AMR parameters

The following lists the related parameters, proper settings and best practices ofAMR. Some aspects of the AMR functionality are explained with the relatedparameters. All the parameters are on cell basis.

Initial codec mode selection

These parameters specify which of the possible speech coding bit rates areimplemented in the serving cell:

. amrConfigurationFR: codecModeSet

. amrConfigurationHR: codecModeSet

Their default values are 12.2, 7.4, 5.9 and 4.75 Kb/s (for FR) and 7.4, 5.9 and4.75 Kb/s (for HR). Remember also that MS supports all speech codec modes,although only a set of up to 4 speech codec modes is used during a call (the codecset can be updated during the call, for example handover) and BSC supports all ofspeech codec modes, except 7.95 kbit/s on the HR channel.

The initial codec mode to start the speech coding operation at call set-up and afterhandover is signalled by layer 3 signalling in which case it is used by the BTSand the MS.

With these parameters you can select a different codec mode from the defaultones:

. amrConfigurationFr: initCodecMode

. amrConfigurationFr: startMode

. amrConfigurationHr: initCodecMode

. amrConfigurationHr: startMode

If the initial codec mode is set to 0 (default), the most robust codec of the onesavailable is chosen (start mode is 00, which is the default value); otherwise if theinitial codec mode is 1 it is possible to choose one of the four codec modesavailable. It is recommended that you choose the most robust codec available(less bit rate for speech).

With initAmrChannelRate parameter you define the initial channel in callset-up (except FACCH call set-up), internal inter cell handover and externalhandover for an AMR call. The default value is Any Rate and this means thatthe chosen channel rate is defined by taking into account the currently usedinformation (Channel Type IE, resource situation on radio interface, circuit pool,current channel rate, handover parameters). The other option is AMR FR, which




means that full rate channel is allocated despite the values of the currently usedinformation. If AMR FR cannot be allocated, then allocation continues with thecurrently used information. The reason behind this last parameter is that qualitymay not be sufficient for HR AMR call set-up (radio measurement is done onSDCCH).

Codec mode adaptation

With the following parameters you can define the thresholds for switching fromone codec mode to another:

. amrConfigurationFr: threshold1: switching from codec mode 2(second lowest bit rate) to codec mode 1 (lowest bit rate most robust)

. amrConfigurationFr: threshold2: switching from codec mode 3to codec mode 2

. amrConfigurationFr: threshold3: switching from codec mode 4(highest bit rate less robust) to codec mode 3.

The recommended values are 4dB, 7dB, and 11dB (in ideal conditionssimulations show that also the values 6dB, 9dB and 13dB give good results interms of FER (Frame Error ate) and mean opinion score (MOS) degradation:higher threshold means that most robust codecs are used, lower thresholds implythat less robust codecs are used.

Aggressive (low C/I) thresholds increase the number of TCH frame errors sincethe high modes are used even with low C/I values. Whereas thresholds that are settoo high decrease the usage of higher modes, thus some speech quality is lost dueto lower number of speech bits.

With the following parameters, together with AMR FR thresholds, it is possibleto define the threshold for switching from one codec mode to another.

. amrConfigurationFr: hysteresis1



The thresholds and the related hysteresis must be in consistent order, that is,AMR FR threshold 1 and AMR FR hysteresis 1 must be equal to or smaller thanthe AMR FR threshold 2 and the AMR FR hysteresis 2 and the AMR FRthreshold 2 and the AMR FR hysteresis 2 must be equal to or smaller than theAMR FR threshold 3 and the AMR FR hysteresis 3.

The following parameters are used for HR configuration:



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. amrConfigurationHr: threshold1



. amrConfigurationHr: hysteresis1



In case of only three codec modes (default HR codecModeSet) threshold 3 andhysteresis 3 are set to 0 in order not to use them.

The basic AMR set for FR and HR channels on the BSC are shown in tablesBasic AMR FR codec set and Basic AMR HR codec set:

Table 2. Basic AMR FR codec set

Codec Mode Threshold (C/I) Hysteresis (C/I)

Lowerthreshold (C/I)

Upperthreshold (C/I)

12.2 11 1 11 -

7.4 7 1 7 12

5.9 4 1 4 8

4.75 - 5

Table 3. Basic AMR HR codec set

Codec Mode Threshold (C/I) Hysteresis Lowerthreshold

Upperthreshold

7.4 14 1 14 -

5.9 11 1 11 15

4.75 - 12




Configuration in handovers

Two of the BSC-related parameters refer to the behaviour during internal andexternal handovers:

. amrConfInHandovers

. amrSetGradesEnabl

With the first parameter it is possible to define the preference between thecurrently used multi-rate configuration and the one defined for the target BTSduring internal and external handovers. With the value 1 (default) the currentlyused multi-rate configuration is preferred in further channel allocations; with thevalue 2, the multi-rate configuration of the target BTS is preferred in furtherchannel allocations.

With the second parameter it is possible to define whether codec mode setdowngrades during internal HOs and upgrades after internal HOs are applied ornot. Its value can be Y or N: with Y downgrades and upgrades are applied, with N(default value) these upgrades and downgrades are not applied.

Handover (HO) and power control (PC) thresholds parameters for AMR

RxQual thresholds (either HO or PC) are specified for FR and HR AMR sets:

Power Control Handover

Pc lower threshold dl Rx qual AMR FR threshold dl Rx qual for AMR FR

Pc lower threshold dl Rx qual AMR HR threshold dl RX qual AMR HR

Pc lower threshold ul Rx qual AMR FR threshold ul Rx qual AMR FR

Pc lower threshold ul Rx qual AMR HR threshold ul Rx qual AMR HR

Pc upper threshold dl Rx qual AMR FR

Pc upper threshold dl Rx qual AMR HR

Pc upper threshold ul Rx qual AMR FR

Pc upper threshold ul Rx qual AMR HR

With these parameters it is possible to define the threshold level of the signalquality down-link/up-link measurements for triggering the handover. The defaultvalues for these new thresholds are set according to the default AMR codec sets.The current Nx and Px values of RxQual thresholds are used.



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If you want to replace or remove the most robust mode on AMR set, thecorresponding PC and HO RxQual thresholds have to be edited manually. Thisalso applies to the least robust mode. Replacement or removal of a middle modeon AMR set does not have an effect on the new PC and HO thresholds.

One solution to benefit from the AMR penetration is to use more aggressive(higher values) power control for the AMR mobiles and thus decrease the averageinterference. This can be done by having different power control thresholds forthe AMR mobiles. By using higher thresholds for AMR mobiles (1-2 classesmore), lower transmission powers are used and as a result, there is lessinterference.

Channel mode adaptation

The RxQual HO thresholds are specified for FR and HR AMR and they are takeninto account when making intra-cell handovers between FR AMR and HR AMR:

. amrHandoverFR

. amrHandoverHR

The current Nx and Px values of RxQual thresholds are used. With theseparameters it is possible to define the threshold level of the signal quality down-link and up-link measurements for triggering the intra-cell handover process foran AMR FR call in order to switch it to an AMR HR call and vice versa.

These two parameters together with the parameters lower limit for FR TCHresources and upper limit for FR TCH resources(btsLoadDepTCHRate) are used to control the packing of FR calls, to HRAMR calls due to cell load and unpacking of HR calls to FR AMR calls due tocall quality. In fact half-rate channels can be used without a noticeable speechquality loss in high C/I conditions. However, with low C/I the speech qualitydecreases a lot and therefore it is essential to choose the best connections whenFR to HR handovers are performed. In addition, if the availability of full-ratetimeslots is good in a certain cell, all connections could be kept in full-rate inorder to optimise the quality and minimise the number of intra-cell handovers. InFigure Packing of FR calls to HE AMR calls due to cell load, there is a simpleexample of how the packing works.

The spontaneous packing of FR AMR calls to HR AMR calls is triggered whenthe cell load is high enough, that is, the number of free full rate resourcesdecreases below the value of the parameter lower limit for the FR TCHresources (according to the BTS-level parameter, if it contradicts with theBSC-level parameter). The packing continues until the cell load is low enough,




that is, the number of free full rate resources increases above the value of theparameter upper limit for FR TCH resources (according to the BTS-level parameter, if it contradicts with the BSC-level parameter). Spontaneouspacking is triggered by any new channel allocation.

Figure 4. Packing of FR calls to HE AMR calls due to cell load

The BSC keeps a record of the FR and HR AMR calls per BTS and thecorresponding counters are updated during channel allocations and releases. Aftera new channel allocation, the BSC makes a request to perform an intra-cell HOfor N number of calls. The packing request is done with a new unacknowledgedprocedure. The BSC performs the ordered HOs for FR AMR calls, the quality ofwhich is above the amrHandoverFR (the intra HO threshold RxQual for AMRFR) and which use the least robust codec mode. A packing request is valid until itis overwritten by a new one. A packing request, which indicates the number N as0, is used to remove any pending packing requests. Moreover, the algorithm triesto fill the timeslots in HR channel pairs or tries to find an empty half for one HRchannel allocation. Before the FR HR handover decision, the number oftimeslots having only one HR connection is measured. For example, if there isonly one half timeslot available, that is allocated first. If more FR HRhandovers are required, they are made in pairs so that two FR connections areselected and allocated to the same timeslot.

Free FR TCHs

Time

Upper limit for free

FR TCHs

Lower limit for free

FR TCHs

No packing of

AMR FR callsPacking of

AMR FR calls

No packing of

AMR FR calls



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The spontaneous unpacking of the HR AMR calls to the FR AMR calls istriggered when the quality of a HR AMR call degrades below theamrHandoverHR (intra HO threshold RxQual for AMR HR). The cell load isnot affected.

The FR and HR AMR call counters of the BSC are again updated during thechannel allocations and releases.

With packing and unpacking, hard blocking decreases compared to a pure FRcase. Moreover, low average TCH FER can be maintained based on the allocationcriteria that only good quality connections are allocated to HR channels.

Prioritisation of AMR capable cells during internal and external handovers

In order to support AMR call continuation also after an internal or external HO,the handover target cell list is manipulated so that the AMR capable cells with alow load are on the top. The candidate cells on the target list are alreadyeliminated by the adjacent cell parameter hoMarginPBGT. The AMR capablecells are verified by the adjacent cell parameter amrDadlbTargetCell (AMRtarget cell of direct access to desired layer) and those AMR capable adjacent cellsare prioritised that are below the threshold of the BTS parameterbtsLoadThreshold (see Figure DADL/B and prioritisation). Prioritisation isonly done when AMR call is the current call type.

Direct access to desired layer/band (DADL/B)

In order to support the 2nd generation BTSs in the AMR environment, DADL/Bis used to hand over AMR calls to co-located AMR capable cells during the callset-up phase. Both intra-BSC and inter-BSC DADL/B handovers are possible andpreferably inside one frequency band as the failure probability is higher withDADL/B handovers between bands. Figure DADL/B and prioritisation shows anexample of DADL/B.




Figure 5. DADL/B and prioritisation

TCH assignment versus DADL/B handover start:

. If an AMR call is the aim and there are no TCHs available in the accessedcell, then Directed Retry (DR) due to congestion, with or without queuing,is made.

. If, on the other hand, there are TCHs available in the accessed cell andthere are adjacent cells defined as DADL/B handover target cells with thenew parameter amrDadlbTargetCell, then the DADL/B handover isapplied. Adjacent cells are not verified according to the MS capabilities(single band, dual band or tri-band), but they have to fulfil the currentsignal level requirements in order to be considered as a target cell forDADL/B handover. The current method for sorting the target adjacent cellsis used.

. if there are no DADL/B handover target cells defined, the TCH is allocatedfrom the accessed cell and another speech codec than AMR is chosen.

Intelligent Frequency Hopping and Intelligent Underlay-Overlay

AMR specific good and bad C/I thresholds are specified for the HR and FRAMR:

1) DADL/B used to direct AMRmobiles to AMR capable cells

2) Prioritisation of AMR capablecells in handovers

2nd gen BTS

UltraSite(co-located)

2nd gen BTS

SDCCH

TCH



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. super reuse good C/I threshold for AMR HR

. super reuse bad C/I threshold for AMR HR

. super reuse good C/I threshold for AMR FR

. super reuse bad C/I threshold for AMR FR

Current Nx and Px values of C/I thresholds are in use.

The new threshold values for the HR AMR also serve the basic HR. The currentgood and bad threshold pair (super reuse good C/I threshold and super reuse badC/I threshold) is going to serve the basic FR.

With these new thresholds you can control which type of speech calls arepreferred to enter the super layers cells, for example HR AMR calls could bepacked to the super layer in order to increase the capacity of regular layer cells(good value for HR AMR - 5 dB compared to the current value and good valuefor FR AMR for example. + 5 dB).




2 AMR compatibilityTable 4. This table indicates which frequency bands support the feature.

Frequency band Compatible

GSM 800 Y

GSM 900 Y

GSM 1800 Y

GSM 1900 Y

Table 5. Compatibility with different network elements (Y = yes, N = no, - =not applicable).

Networkelement

Compatible Release Notes

MSC Y M10

Nokia NetAct Y OSS3.1

BSC Y S10 All the Nokia BSCsand TCSM2 withsoftware versionS10 onwards havefull AMR supportexcept 7.95 kbit/son HR channel.

SGSN -

NetAct Planner Y 4.0

Nokia 2nd Gen. N



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AMR compatibility

Table 5. Compatibility with different network elements (Y = yes, N = no, - =not applicable). (cont.)

Networkelement

Compatible Release Notes

Nokia Talk-family Y DF6 Nokia Talk-familyBTSs have AMRsupport for FRmodes 4.75, 5.9,7.4 and 12.2 aswell as for HRmodes 4.75, 5.9and 7.4 withsoftware versionDF 6.0 onwards.With thisapproach, the linkadaptationbetween full scaleof FR modes andalmost full scale ofHR can beachieved.

Nokia PrimeSite Y DF6 FH is removed ifAMR isimplemented.Nokia PrimeSiteBTS AMR supportis similar to that ofNokia Talk-familyBTS. Due to thelimited DSPprocessor/memorycapacity thefrequency hoppingfunctionality isremoved fromPrimeSite BTSs toenable this SWmodification. Thismeans that the lastPrimeSite SWrelease supportingfrequency hoppingis DF5.0.

Nokia MetroSite Y CXM3.0

Nokia InSite N

Nokia UltraSite Y CXM3.0




Table 6. This table indicates whether the feature hasparameters that are managed with MMI (Y = yes, -= not applicable).

MMI Parameters Notes

BSC MMI Y

BTS MMI -

Table 7. This table indicates whether the feature requiresadditional or alternative hardware or firmware (Y=additional, A= alternative, or - = not applicable).

Networkelement

Additional oralternative HW/FWrequired

Notes

BSC -

BTS -

TC A TCSM2 with newpools required.

SGSN -

Table 8. This table indicates whetherthe feature sets specialrequirements to mobilestations, and whether thefeature is an optional or astandard BSS feature.

MS AMR capable MSrequired

STD/OPT O



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AMR compatibility

Related topics

Overview of Adaptive Multirate Codec




3 Overview of planning AMRSummary

For an overview of the feature, see Overview of Adaptive Multi Rate Codec(AMR).

The implementation procedure for AMR includes the following:

Steps

1. Activating AMR in MSC

2. Activating AMR in BSC

Further information

If you want to deactivate the feature, see Deactivating AMR.



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Overview of planning AMR

4 Activating AMR in MSCIt is important to follow these instructions carefully in order to succeed in takingthe feature into use.

Note

Steps 1 and 2 are executed in the BSC.

Steps

1. Change the direction of circuits

2. Create the connection from the BSC to the MSC (Reversed Hunting inthe BSC)

3. Lock the BSC

ZEDS:NO=:L;

4. Create incoming CGR to the MSC

ZRCC:TYPE=CCS,NCGR=,CGR=:DIR=IN,NET=NA0,LSI=AIF01,SPC=:INR=IMCG0,TREE=,NCCP=BSSAP;

Note

Parameter TREE is obligatory, but never used. The tree number can thus bedefined as any number.



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Parameter NCGR should be named so that it can be identified with a BSC. This isbecause only NCGR gives information on which CGRs are tied to a certain BSC.You can check it with an MML of the Circuit Group Handling (RC) commandgroup.

5. Create PCM timeslots under CGR

ZRCA:NCGR=:CRCT=:BL;

ZCEC:CRCT=

b. Ensure that circuit pools are used in the A-interface, if allroutes towards the BSC do not support all type of channels,that is, full rate, half rate, enhanced full rate, adaptive multi-rate. This is relevant if remote transcoders are used by theBSC and part of transcoders do not support the adaptivemulti-rate codec.

c. Define routes to the BSC through AMR transcoders by theAMR pool (pool number 23). If the BSC does not use theremote transcoders, the route between the MSC and the BSCshould be defined as 'Not Applicable Pool' (pool number 0).

Routes and circuit groups are handled with the MSC MMLwith commands of the Route Handling (RR) command group.To create a route, that is, to connect a circuit group to theroute, use the RRC command:

Further information

Example:

a. ZRCC:TYPE=CCS,NCGR,CGR=:DIR=OUT,NET=NA0,LSI=AIF01,SPC=;

b. ZRCA:NCGR=:CRCT=:BA;



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ZCEC:CRCT=

5 Activating AMR in BSCThese instructions cover all actions to be done in the BSC to take AMR into use.

Summary

The procedure consists of the following phases

. Switching the feature-specific control parameter on (step 1).

. Adding and modifying circuits in the BSC (step 2).

. Configuring radio network parameters (steps 3-6).

For detailed instructions and command parameters, see BSS Integration inBSC documentation.

. Testing AMR (steps 7-9).

The test requires an MSC/VLR, BSC and a mobile.

The BSC should be defined to use reversed circuit allocation by the BSC.The BSC will be in a locked status, that is the circuits are not in use. Thismeans that traffic will be cut off, therefore it is recommended to take thefeature in use during some 'low traffic hours'.

Steps

1. Switch on the AMR_CODEC_USED parameter

ZWOA:2,619,A;

2. Modify speech circuits

You must change the type of the first TC-PCM from FR to AMR (pool 1 ->pool 23). There are currently two ways to do this: speech circuits can beremoved and added during modification or speech circuits can betransferred automatically during modification. Choose one of thefollowing:



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. Remove and add speech circuits during modification.

a. Remove the speech circuits of the first TC-PCM from thecircuit group that contains circuits of pool 1.

ZCEC:ETPCM=,CRCT=1-1&&-31:BA (or BL);

ZCEC:ETPCM=CRCT=1-1&&-31:NU;

ZRCR:NCGR=,ETPCM=,CRCT=1-1&&-31;

b. Modify the TC-PCM type.

ZWGM:,1:POOL=23;

c. Restart the TCSM unit.

This must be done because the TC-PCM type in the TCSM2is changed and the TCSM unit is in WO-EX state. TheTCKONF-MML notifies about this during ZWGM command.

ZUSU:TCSM,ZUSU:TCSM,

d. Add speech circuits to the circuit group that contains circuitsof pool 23.

ZRCA:NCGR=,ETPCM=,CRCT=1-1&&-31,CCSPCM=3;

ZCEC:ETPCM=,CRCT=1-1&&-31:BA;

ZCEC:ETPCM=,CRCT=1-1&&-31:WO;. Modify circuits with automatic circuit transfer

a. Block speech circuits of the TC-PCM.

ZCEC:ETPCM=,CRCT=1-1&&-31:BA (or BL);

b. Modify the TC-PCM type.

Note that the target circuit group has to exist.

ZWGM:,1:POOL=23:NCGR=;

c. Restart the TCSM unit.

This must be done because the TC-PCM type in the TCSM2is changed and the TCSM unit is in WO-EX state. TheTCKONF-MML notifies about this during ZWGM command.

ZUSU:TCSM,

d. Unblock speech circuit of the TC_PCM.

ZCEC:ETPCM=,CRCT=1-1&&-31:WO;

3. Modify AMR parameters (EQY and EQO commands)




With the EQY command you modify the BTS Adaptive Multi Rate SpeechCodec (AMR) parameters in the BSDATA. The command is optional andis supported by the following BTS generation types: Nokia Talk-Family,Nokia PrimeSite, Nokia MetroSite and Nokia UltraSite.

4. Modify AMR signal quality threshold parameters of the BTS (EHB,EHC and EHO commands)

With the EHB command you modify the AMR signal quality thresholdparameters of the BTS in the BSDATA. The command is optional.

5. Modify AMR signal quality threshold parameters related to PC (EUB,EUC and EUO commands)

With the EUB command you modify the AMR signal quality thresholdparameters related to power control in the BSDATA. The command isoptional.

6. Define the AMR other parameters within the BSS (EEM and EEOcommands)

7. Make a call via the BSC that has enhanced circuit allocation support

8. Perform adaptive multi-rate speech codec test

9. Make a call using a mobile station supporting multi-rate speech codec

Expected outcome

. Enhanced A-interface allocation working if the call via the BSC thathas circuit allocation support is successful.

. Adaptive multi-rate test.

. In the tests, the speech with adaptive multi-rate speech coding issuccessful when acceptable speech quality is achieved and no alarmsare given in the system, which relate to the adaptive multi-ratefunctioning. The selected A-interface resource can be checked forexample from call record information (MMI: MCJ).

Further information




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Activating AMR in BSC

6 Deactivating AMRThe feature cannot be switched off, but it is possible to create the BSC withoutusing reversed circuit allocation.

Steps

1. Lock the BSC

ZEDS:NO=:L;

2. Set the circuit allocation by the BSS to OFF in the BSC

This command is executed in the MSC.

ZEDH:NO=:OFF;

After the feature is switched off, the BSC cannot set the unlocked statebecause the CGR direction is IN. If the BSC should be used like anordinary BSC, CGR pcm-tsl's state must be changed to NU state and afterthat the CGR can be deleted.

3. Create the BSC like an ordinary BSC

4. It is possible to set Adaptive multi-rate speech codec support OFF inthe used BSSAP version

ZEDT:VER=:F,50,0;

5. Test the deactivation by clearing test calls

Further information




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GSM/EDGE BSS network planning and implementation for AMRContents1 Overview of Adaptive Multi Rate Codec, AMR1.1 Link adaptation1.2 Channel allocation1.3 Requirements for AMR activation in Nokia networks1.4 AMR parameters

2 AMR compatibility3 Overview of planning AMR4 Activating AMR in MSC5 Activating AMR in BSC6 Deactivating AMR

amr planning & implementation

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