Half Rate Service

12 Half-Rate Service

About This Chapter

12.1 OverviewThe half-rate service is optional.

12.2 AvailabilityThis lists the NEs, software, and licenses in the number of TRXs supporting half-rate servicesfor the implementation of half-rate services.

12.3 Technical DescriptionThis describes the technical aspects of half-rate services, including the channel assignmentstrategies related to the half-rate service, the rate adjustment algorithms, and the resourcereservation function involved in the rate adjustment.

12.4 CapabilitiesBSC6000V900R001C01 supports up to 2048 TRXs that can provide half-rate services.

12.5 ImplementationThis describes how to configure half-rate services, verify half-rate services, activate the functionof reserving priority resources, adjust half-rate services, and deactivate half-rate services.

12.6 Maintenance InformationThis lists the performance counters related to the half-rate service.

12.7 ReferencesNone.

HUAWEI BSC6000 Base Station SubsystemBSS Feature Description 12 Half-Rate Service

Issue 03 (2008-01-25) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd

12-1

12.1 OverviewThe half-rate service is optional.

Definition

The half-rate service is a service where the speech coding rate is reduced to half of the full-ratespeech coding rate through a new speech coding algorithm. If the half-rate service is enabled,the physical channel carrying the service of only one calling MS is able to bear the services oftwo calling MSs.

Purposes

If the half-rate service is enabled, the number of system-enabled MSs holding speech servicesis doubled without the addition of TRXs. Thus the frequency reuse rate is enhanced. The telecomoperators can fully utilize the network resources and minimize the operation cost.

Terms

Terms Definition

Couple A timeslot composes of two half-ratesubtimeslots. When the two half-ratesubtimeslots are idle, the channel where twosubtimeslots are located is the Couplechannel.

Single A timeslot composes of two half-ratesubtimeslots. When one subtimeslot isoccupied and the other subtimeslot is idle, thechannel where the idle subtimeslot is locatedis the Single channel.

TCHF Full-rate speech channel

TCHH Half-rate speech channel

Rate adjustment The conversion from a full-rate channel to ahalf-rate channel or from a half-rate channelto a full-rate channel

Half-rate version 1 HR data (with the rate of 5.6 kbit/s)

Half-rate version 2 Reserved for protocols

Half-rate version 3 HAMR data (with the rate ranging from 4.75to 7.4 kbit/s)

Full-rate version 1 FR data (with the rate of 13 kbit/s)

Full-rate version 2 EFR data (with the rate of 12.2 kbit/s)

12 Half-Rate ServiceHUAWEI BSC6000 Base Station Subsystem

BSS Feature Description

12-2 Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd

Issue 03 (2008-01-25)

Terms Definition

Full-rate version 3 FAMR data (with the rate ranging from 4.75to 12.2 kbit/s)

Acronyms

Acronyms Full Spelling

AMR Adaptive Multi-Rate

EFR Enhanced Full Rate

FR Full Rate

HR Half Rate

12.2 AvailabilityThis lists the NEs, software, and licenses in the number of TRXs supporting half-rate servicesfor the implementation of half-rate services.

NEs Involved

Table 12-1 describes the NEs involved in the half-rate service.

Table 12-1 NEs involved in EFR

MS BTS BSC MSC MGW SGSN GGSN HLR

√ √ √ √ – – – –

NOTE

l -: not involved

l √: involved

Software Releases

Table 12-2 describes the software releases that support the half-rate service.

Table 12-2 GBSS products and software versions

Product Version

BSC BSC6000 V900R003C01 andlater releases



12-3

Product Version

BTS BTS3X G3BTS32.30000.01.1130 and later releases

BTS3002C G3BTS36.30000.02.0820 and later releases

BTS3001C G3BTS34.30000.07.0301

Double-transceiver BTSs All releases

Miscellaneous

Only when the license is obtained, the half-rate service can be enabled.

The license in the number of TRXs supporting the half-rate service needs to be requested for.The number of TRXs supporting the half-rate service must be within the range allowed by thelicense so that the TRXs can work normally.

12.3 Technical DescriptionThis describes the technical aspects of half-rate services, including the channel assignmentstrategies related to the half-rate service, the rate adjustment algorithms, and the resourcereservation function involved in the rate adjustment.

The rate adjustment consists of the following:

l Adjustment from the TCHH to the TCHF

l Adjustment from the TCHF to the TCHH

l Adjustment from the PDCH to the TCHH

l Adjustment from the TCHH to the packet PDCH

The dynamic rate adjustment is triggered in the channel assignment procedure. Thus the ratecan be adjusted in real time.

Based on the channel request type, the full-rate or half-rate selection procedure is triggered onlywhen the type of the request channel is half rate TCH only, half rate TCH preferable, full rateTCH only, or full rate TCH preferable.

After the TCH Rate Adjust Allow is enabled, for the channels that are not requested for in theimmediate assignment procedure or the handover channel requests not caused by the dynamicadjustment of other channels, the following adjustment mechanism is adopt :

l If a half-rate channel is requested for, the dynamic adjustment from a full-rate channel toa half-rate channel is triggered.

l If a full-rate channel is requested for, the dynamic adjustment from a half-rate channel toa full-rate channel is triggered and a handover may be triggered.

l If the channels for immediate assignment or the full-rate/half-rate dynamic adjustmentcannot be found in the current cell, the BSC requests the PCU to covert channels.




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l When the PCU requests for a channel and the configuration type of the channel is a dynamicPDCH, the TCHH is converted to the PDCH if the current channel type is TCHH.

NOTE

For the PDCH that carries the PS service, the channel type is PDCH. When the BSC requests the PCU toconvert channels, the PCU releases a channel. If the call requests the full rate TCH only, the system convertsthe channel to the full rate TCH. In other cases, the system converts the channel to the half rate TCH andassigns the channel to the calls in the queue.

12.3.1 Channel Assignment StrategiesIf the half-rate service is enabled, the BSC selects different channel assignment algorithms basedon the channel assignment strategies in the data configuration after the BSC receives anAssignment Request message from the MSC.

12.3.2 Rate Adjustment AlgorithmsRate adjustment algorithms consist of different request types of rate adjustment algorithms andthe full-rate and half-rate adjustment procedures.

12.3.3 Function of Reserving Priority ResourcesThe function of reserving priority resources is used to ensure the service quality of high priorityusers by reserving certain full-rate speech channels for these users.

12.3.4 Estimation of the Number of the Full-Rate and the Half-Rate Channels in a CellIn some situations, users need estimate the number of the full-rate and half-rate channels in acell.

12.3.1 Channel Assignment StrategiesIf the half-rate service is enabled, the BSC selects different channel assignment algorithms basedon the channel assignment strategies in the data configuration after the BSC receives anAssignment Request message from the MSC.

There are two channel assignment strategies:

l Channel rate assignment strategy controlled by the MSC

l Channel rate assignment strategy controlled by the BSC

By default, the channel rate assignment strategy controlled by the BSC is used.

In channel assignment algorithms, the system determines to assign half-rate channels or full-rate channels based on the traffic volume of the network. If one of the following conditionsoccurs, you can infer that the network is busy:

l The channel seizure ratio exceeds the TCH Traffic Busy Threshold.

NOTE

Channel seizure ratio = (Number of busy full-rate channels + Number of busy half-rate channels/2)/(Number of available full-rate channels + Number of available half-rate channels/2) x 100%

Here, full-rate or half-rate channels contain the dynamic PDCHs that do not carry any packet services.

l For the AMR calls, the channel seizure ratio exceeds the AMR TCH/H Prior Cell LoadThreshold.

l In a concentric cell, when the Load of Inner Cell or Out Cell for rate SelectingAllowed is enabled:

– For the calls in the OL subcell, the channel seizure ratio of the OL subcell exceeds TCHTraffic Busy Overlay Threshold.



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– For the calls in the UL subcell, the channel seizure ratio of the UL subcell exceeds TCHTraffic Busy Underlay Threshold.

l For the dynamic Abis, when the Abis Resource Adjustment TCHH Function Switch isenabled, the fixed Abis channel seizure ratio exceeds the Fix Abis Prior Abis LoadThreshold and the dynamic Abis channel seizure ratio exceeds the Flex Abis Prior AbisLoad Threhold.

l When the Switch of 8K On Ater is enabled, the Ater resource usage ratio exceedsCongestion Ration on Ater Resource(%).

If the network is busy, half-rate channels are assigned preferably. If the network is not busy,full-rate channels are assigned preferably.

In the channel assignment, the rate adjustment is triggered based on the usage state of channelsin the cell. After the rate adjustment is triggered, channels are assigned to the current calls. Thusthe rate is adjusted in real time.

The system assigns radio resources as follows:l When the network is idle, full-rate channels are assigned preferably to ensure the speech

quality. When the network is busy, half-rate channels are assigned preferably to ensure thatmore users can enjoy services.

l Detect whether the network is busy by comparing the channel seizure ratio and theconfigured threshold. If the channel seizure ratio is higher than the configured threshold,you can infer that the network is busy.

l For half-rate calls, the channels on Singles are assigned preferably. Thus the half-ratechannels are seized collectively and fragments are minimized.

l When the rate is sufficient to provide services, the channels on the TRXs that do not supportrate adjustment are assigned preferably. Therefore, the channels on the TRXs that supportthe rate adjustment can be reserved for further use. The resources can be used maximally.

NOTE

Only when the BSC channel assignment strategy is selected, the type of the resources (HR or FR resources)that need to be assigned can be determined based on the network busyness.

12.3.2 Rate Adjustment AlgorithmsRate adjustment algorithms consist of different request types of rate adjustment algorithms andthe full-rate and half-rate adjustment procedures.

12.3.2.1 Different Request Types of Rate Adjustment AlgorithmsRate adjustment algorithms vary with the types of rates for requested channels.

12.3.2.2 Full-Rate/Half-Rate Adjustment ProcedureFull-rate/half-rate adjustment consists of the adjustment from a full-rate channel to a half-ratechannel and the adjustment from a half-rate channel to a full-rate channel.

12.3.2.3 Half-Rate/PDCH Adjustment ProcedureHalf-rate/PDCH adjustment consists of the adjustment from a half-rate channel to a PDCH andthe adjustment from a PDCH to a half-rate channel.

Different Request Types of Rate Adjustment AlgorithmsRate adjustment algorithms vary with the types of rates for requested channels.

There are three types of channel rates in a channel assignment request:




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l Full rate TCH only

l Half rate TCH only/half rate TCH preferable

l Full rate TCH preferable

If the type of the rate in a channel assignment request is full rate TCH only, the channel requestis accepted when the following requirements are met. If the type of the rate in a channelassignment request is not full rate TCH only or if the following requirements are not met, thechannel request is rejected.

l If there is an idle full-rate channel, the BSC assigns the channel directly.

l If there is no idle full-rate channel but there is an idle Couple, the BSC converts the Coupleinto a full-rate channel, and then assigns the full-rate channel.

l If there is no idle full-rate channel and there is no idle Couple, but there is an idle Single,the BSC determines whether the number of adjustable idle half-rate channels in a cellexceeds 1. If the number of adjustable idle half-rate channels in a cell exceeds 1, an intra-cell handover is initiated. The BSC coverts the Couples after the handover into full-ratechannels, and then assigns the full-rate channels. If the number of adjustable idle half-ratechannels in a cell does not exceed 1, the channel assignment request is rejected.

Figure 12-1 Full rate TCH only channel adjustment procedure

Yes

No

No

Yes

No

Yes

Start

Whether thereare appropriate full-rate

channels?

TCHF only requests

Whether there areappropriate

Couple channels?

Whether there aremore than one half-rate

channels?

Convert all the Couple channels into the full-rate channels

Initiate an intra-cell handover,and then convert all the Couple

channels formed after thehandover into the full-rate channels

Assign full-rate channelsReject requests

End

If the type of the rate in a channel assignment request is half rate TCH only or half rate TCHpreferable, the channel request is accepted when the following requirements are met. If the type



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of the rate in a channel assignment request is not half rate TCH only or half rate TCH preferable,or if the following requirements are not met, the channel request is rejected.

l If there is an idle Single, the BSC assigns the Single directly.

l If there is no idle Single but there is an idle Couple, the BSC assigns the idle half-ratechannel on the Couple.

l If there is no idle Single and there is no Couple, but there is an idle full-rate channel, anadjustment is triggered. The BSC converts the full-rate channel into a Couple, and thenassigns the idle half-rate channel on the Couple.

NOTE

If the BSC assigns the channels on Singles preferably, the half-rate channels can be seized collectivelyand fragments can be minimized.

Figure 12-2 Half rate TCH only/half rate TCH preferable channel adjustment procedure

Yes

No

No

Yes

No

Yes

Start


Single channels?

Half-rate request


Couple channels?


full-rate channels?

Convert thefull-rate channels into the

Couple trannels

Assign thehalf-rate channelsChannels fail to be assigned

End

If the type of the rate in a channel assignment request is full rate TCH preferable, the channelrequest is accepted when the following requirements are met. If the type of the rate in a channelassignment request is not full rate TCH preferable or the following requirements are not met,the channel request is rejected.

l If there is an idle full-rate channel, the BSC assigns the channel directly.

l If there is no idle full-rate channel but there is an idle Couple, the BSC converts the Coupleinto a full-rate channel, and then assigns the full-rate channel.




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l If there is no idle full-rate channel and there is no idle Couple, but there is an idle Single,the BSC determines whether the number of adjustable idle half-rate channels in a cellexceeds 1. If the number of adjustable idle half-rate channels in a cell exceeds 1, anadjustment is triggered and an intra-cell handover is initiated. The BSC coverts the Couplesafter the handover into full-rate channels, and then assigns the full-rate channels. If thenumber of adjustable idle half-rate channels in a cell does not exceed 1, the BSC assignsthe idle Single.

Figure 12-3 Full rate TCH preferable channel adjustment procedure

Yes

No

No

Yes

No

Yes

Start


full-rate channels?

TCHF preferred request

Whether there areappropriate Couple

channels?


channels?

Convert all the Couplechannels into the full-rate channels

Initiate an intra-cell handoverand convert the Couple

channels formed after thehandover into the full-ratechannels

Assign the full-rate channelsAssign the half-rate channels

End

NOTE

Only when the Enhanced TCH Adjust Allowed is enabled, the calls on a Single can be handed over, andthen an adjustment is triggered when a half-rate channel is converted into a full-rate channel.

Full-Rate/Half-Rate Adjustment ProcedureFull-rate/half-rate adjustment consists of the adjustment from a full-rate channel to a half-ratechannel and the adjustment from a half-rate channel to a full-rate channel.



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Adjustment from a Full-Rate Channel to a Half-Rate Channel

1. If the related resources are not assigned for the channel application, the channel applicationenters the queue. The queuing duration is set through the "Timer of Waiting Channel Adjust(ms)." By default, the duration is three seconds.

l Queuing fails

– For the request for full-rate only or half-rate only type, the queuing fails.

– For the request for full-rate preferred or half-rate preferred, channels that are selectedsecondarily, such as, Couples or full-rate channels are assigned. For detailed decisionprocedure, refer to Figure 12-4. The procedure is complete.

Figure 12-4 Half rate TCH only/half rate TCH preferable channel adjustmentprocedure

Yes

No

No

Yes

No

Yes

Start


Single channels?

Half-rate request


Couple channels?


full-rate channels?

Convert thefull-rate channels into the

Couple trannels

Assign thehalf-rate channelsChannels fail to be assigned

End

l Queuing succeeds

The BSC adjusts a full-rate channel to two Couples, sets the necessary values of channelattributes, initiates the command of adjusting the BSC timeslots, enables the "Timer ofWaiting BMRC Response(ms)", and takes statistics of related performancemeasurement. If the Flex Abis is enabled, go to step 2 directly and the BSC takesstatistics of related performance measurement.

2. The BSC sends the command of adjusting and setting the channel attributes to the BTSbefore adjusting the BSC timeslots. If the time of processing the commands of adjusting




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the BSC timeslots and adjusting the channel types that are sent to the BTS expires, as longas the system is normal, the adjustment command is reinitiated.

3. After receiving the command, the BTS starts converting channels. After channels areconverted, the BTS sends the "Status Change Report" to the BSC.

4. After receiving the "Status Change Report", the BSC sets the converted Couples to idle andavailable. The BSC completes the adjustment, assigns channels to the current call in thequeue, and takes statistics of related performance measurement.

Adjustment from a Half-Rate Channel to a Full-Rate Channel1. If the current channel is a Couple, the corresponding channel request enters the queue. The

queuing duration is set through the "Timer of Waiting Channel Adjust (ms)." By default,the duration is three seconds.l Queuing fails


– For the request for full-rate preferred or half-rate preferred, channels that are selectedsecondarily, such as, Couples or Singles are assigned. For detailed decisionprocedure, refer to Figure 12-5 and Figure 12-6. The procedure is complete.

Figure 12-5 Full rate TCH only channel adjustment procedure

Yes

No

No

Yes

No

Yes

Start

Whether thereare appropriate full-rate

channels?

TCHF only requests


Couple channels?


channels?

Convert all the Couple channels into the full-rate channels

Initiate an intra-cell handover,and then convert all the Couple

channels formed after thehandover into the full-rate channels

Assign full-rate channelsReject requests

End



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Figure 12-6 Full rate TCH preferable channel adjustment procedure

Yes

No

No

Yes

No

Yes

Start


full-rate channels?

TCHF preferred request

Whether there areappropriate Couple

channels?


channels?

Convert all the Couplechannels into the full-rate channels

Initiate an intra-cell handoverand convert the Couple

channels formed after thehandover into the full-ratechannels

Assign the full-rate channelsAssign the half-rate channels

End

l Queuing succeeds

The BSC adjusts two Couples to a full-rate channel. For the subsequent procedure, referto Adjustment from a Full-Rate Channel To a Half-Rate Channel. The BSC setsthe necessary values of channel attributes. If the Flex Abis is not enabled, the BSCinitiates the command of adjusting the BSC timeslots, informs the BTS of completingthe channel conversion, and takes statistics of related performance measurement.

2. If the current channel is a Single, the corresponding channel request enters the queue. Thequeuing duration is set to 5.5 seconds, because the defragmentation requires a long time.

l Queuing fails


– For the request for full-rate preferred or half-rate preferred, the Single is assigned.For detailed decision procedure, refer to Figure 12-5. The procedure is complete.

l Queuing succeeds

The system initiates an mandatory intra-cell handover on another occupied half-ratechannel that is corresponding to the Single. The handover is not controlled by the relatedconfiguration of handover. The system initiates the "Timer of Waiting CRDLC HOResponses(s)" and reserves sufficient time for the intra-cell handover.




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Different operations are performed based on whether a forced handover response isreceived.– If a forced handover response is received, the "Timer of Waiting CRDLC HO

Responses(s)" is stopped. The BSC judges whether the forced handover succeeds.If the forced handover fails, an appropriate call needs to be found in the queue toassign the Single. The other occupied half-rate channel is not released. If the forcedhandover succeeds, the channel status is set to "waiting for releasing the channe"l,when the channel status is set to "the service is idle", refer to the Couple adjustmentprocedure to perform the dynamic adjustment.

– If a forced handover response is not received, but the "Timer of Waiting CRDLCHO Responses(s)" expires, the handover fails. A handover failure procedure isperformed.

Half-Rate/PDCH Adjustment ProcedureHalf-rate/PDCH adjustment consists of the adjustment from a half-rate channel to a PDCH andthe adjustment from a PDCH to a half-rate channel.

Adjustment from a Half-Rate Channel to a PDCH1. When an MS initiates the PS services, the PCU specifies a CS timeslot if there is no PS

channel, and then obtains the current channel type, usage state, and the flag that identifieswhether the PDCH assignment request can preempt the channels of CS services.



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Figure 12-7 Half-rate /PDCH channel adjustment procedure

Yes

Start

The PCU specifies a CS timeslot

The channelassignment fails

End

No

The channelssignment succeeds

Yes

No

Yes

No

No

Yes

Yes

No

Does the timeslotmeet the adjustment

requirements?Is the

timeslot idle?

Does the systeminitiate an intra-cell

handover?

Is the priority of the PSservice is higher than that

of the CS service?

Is the intra-cellhandover successful?

2. If the timeslot meets the adjustment requirements, the system performs operations asfollows:l If the timeslot specified by the PCU is idle, the system converts the channel on the

timeslot to PDCH, and then the BSC sends the message that the channel requestsucceeded to the PCU.

l If the timeslot specified by the PCU is busy, the cell initiates an intra-cell handover,that is the timeslot integration. The timeslot can be either a full-rate timeslot or a half-rate timeslot.

(1) Before initiating the intra-cell handover, the system determines whether there areenough idle timeslots in the current cell, and then performs the operations asfollows:– If there is no idle timeslots including full-rate and half-rate timeslots in the

current cell, the intra-cell handover is not performed.– If the channel requested by the PCU is a half-rate channel and there is only one

idle timeslot, the intra-cell handover is not performed. If the system cannotinitiate an intra-cell handover, the system determines whether the priority ofthe PS service is higher than that of the CS service.




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– If the priority of the PS service is higher, the system releases the channelon the specified timeslot forcibly and converts the channel to PDCH.

– If the priority of the CS service is higher, the system sends the request failuremessage to the PCU.

(2) If there are enough idle timeslots in the current cell, the system initiates the intra-cell handover, that is the timeslot integration. The timeslots can be either full-ratetimeslots or half-rate timeslots.– If the system initiates an intra-cell handover and the handover succeeds, the

channel on the specified timeslot is converted to PDCH.– If the intra-cell handover times out, the system detects whether the priority of

the PS service is higher.– If the priority of the PS service is high, the system releases the channel on

the specified timeslot forcily and converts the channel to PDCH.– If the priority of the CS service is higher, the system sends the request failure

message to the PCU.

NOTE

To avoid new intra-cell handover is triggered during the channel conversion of an intra-cell handover, the dynamic PDCH is not switched back and the system does not performhalf-rate/full-rate adjustment, and queuing and preemption.

(3) If there is no enough timeslots in the current cell, the system detect whether thepriority of the PS service is higher.– If the priority of the PS service is high, the system releases the channel on the

specified timeslot forcibly and converts the channel to PDCH.– If the priority of the CS service is higher, the system sends the request failure

message to the PCU.(4) If the intra-cell handover times out, the system detects whether the priority of the

CS service is higher.– If the priority of the PS service is high, the system releases the channel on the

specified timeslot forcibly and converts the channel to PDCH.– If the priority of the CS service is higher, the system sends the request failure

message to the PCU.



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Adjustment from a PDCH to a Half-Rate Channel

CAUTIONPay attention to the following points in the adjustment from a PDCH to a half-rate channel:l The BSC requests that the dynamic PDCH converted by the PCU must meet the requirements

of the CS calls. Thus the factors such as the frequency bands and concentric cells should beconsidered during the conversion.

l If the type of the assigned channel required by the CS calls is half rate TCH only and theBSC determines that the rate adjustment is not supported by the TRX where one of thedynamic PDCHs to be converted is located, the BSC does not request the PCU to convertthe dynamic PDCH.

l The BSC should not assign the dynamic PDCH for the CS services.The priority of channels contains the dynamic PDCH bit. If the initial configuration type isa dynamic PDCH, the bit that indicates the priority of channel types is set to 1. That is, thepriority is low. In other similar conditions, as the weight of dynamic PDCH is heavier, thepriority is lower.

1. When no available channels can be assigned to the CS calls, the BSC sends the channelrequest message to the PCU. The BSC requests the PDCH to convert to the half-rate channeland puts the current calls in a queue.

Figure 12-8 Half-rate/PDCH channel adjustment procedure

Yes

Start

The BSC sends thechannel request to the PCU

The channelassignment fails

End

No

The channel assignmentsucceeds

YesNoEnable the TCH ReqSuspend Interval timer

Covert thePDCH to TCHF

Conver the PDCH toTCHH

Half rateTCH preferable andthe TCH Rate AdjustAllow is set to Yes?

Doesthe BSC receive the

acknowledgement of thechannel request?

2. After the BSC receives the acknowledgement of the channel request, it performs operationsas follows:




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l If the CS calls request full-rate channels or the TCH Rate Adjust Allow is set to No,the system converts PDCH to TCHF.

l If the CS calls request half rate TCH preferable or the TCH Rate Adjust Allow is setto Yes, the system converts PDCH to TCHH.

3. After receiving the reject message of the channel application, the BSC enables the TCHReq Suspend Interval.

NOTE

l The call queuing mode is used in the dynamic adjustment. Since the call is in the queue before the BSCsends the channel application to the PCU, queuing times out and the call is released.

l If there is no call in the queue when the PCU releases the PDCH, the system converts PDCH to TCHF.

12.3.3 Function of Reserving Priority ResourcesThe function of reserving priority resources is used to ensure the service quality of high priorityusers by reserving certain full-rate speech channels for these users.

After half-rate services are enabled, the coding rate is 5.6 kbit/s, because the coding scheme isdifferent from that of full-rate service. Thus the speech quality is decreased.

Some outdated or cheap MSs used by some low-end users do not support half-rate services. Inthe cells that half-rate services are enabled, these users occupy the full-rate channels to obtainthe services of high quality. However, since the MSs of some high-end users support half-rateservices, in the cells that the half-rate is enabled, these MSs preferably choose the half-ratechannels. This makes it possible that these high-end users obtain services of low quality.

If the function of reserving priority resources is configured, full-rate channels are assigned tothe MSs of high priority users even if the cell is busy.

12.3.4 Estimation of the Number of the Full-Rate and the Half-RateChannels in a Cell

In some situations, users need estimate the number of the full-rate and half-rate channels in acell.

The full-rate and half-rate channels in a cell can be configured appropriately according to theestimated number of channels. Set the TCH Traffic Busy Threshold(%) according to theestimated proportion of full-rate and half-rate channels. Enabling the TCH Rate AdjustAllow of all the TRXs in the cell makes the adjustable number of full-rate and half-rate channelsto be appropriate according to the traffic volume.

Available Information

The traffic volume in a cell is 1 Erl and the call loss rate that is permitted by an operator is B%.Therefore, the number of the required channels in the cell is n. If the number of TRXs in the cellis m, the number of the service timeslots that can be supplied by the cell is a. Therefore, thenumber of service channels that can be supplied by the cell ranges from a to 2a.

Rules

Based on the traffic volume (1 Erl) and the allowed call loss rate described in ERLANG B, thenumber of the channels required in the cell is n.



12-17

l If n <= a, all the service channels in the cell can be configured as TCHFs.The TCH Traffic Busy Threshold(%) is set to 100. If the AMR exists, the AMR TCH/H Prior Cell Load Threshold is set to 99. Dual-rate MSs select the full-rate channels.

l If 2a > n > a, the number of TCHFs (f) configured in the cell must meet the condition, thatis, f + 2 (a-f) > n (f = [2a-n]). Other timeslots are configured as the TCHHs.The TCH Traffic Busy Threshold(%) is set to 100 x [2a-n]/a. If the AMR exists, theAMR TCH/H Prior Cell Load Threshold is set to be smaller than 100 x [2a-n]/a. Whenthe traffic volume in the cell is large, the dual-rate MSs select the half-rate channels.

l If n >= 2a, one or two service channels are configured as TCHFs in the cell. Other channelsin the cell are configured as the TCHHs. At the same time, Huawei recommends that thecapacity of the cell be expanded. The configured TCHFs are mainly reserved for the MSsthat can use only TCHFs. The call loss rate is greater than B%.The TCH Traffic Busy Threshold(%) is set to 0. If the AMR exists, the AMR TCH/HPrior Cell Load Threshold is set to 0. Dual-rate MSs select the full-rate channels.

ExamplesIf a cell holds two TRXs, the cell is configured with one BCCH and two SDCCHs.

Based on ERLANG B, if the traffic volume is X, the number of configured channels is 10. Thenumber of channels that can be configured as TCHs in the cell is 13 (2 x 8 - 3). Because 13 >10, all the channels in the cell can be configured as TCHFs. The TCH Traffic Busy Threshold(%) can be set to 100. The AMR TCH/H Prior Cell Load Threshold is set to 99.

Based on ERLANG B, if the traffic volume in the cell is Y, the number of configured channelsis 17 and the number of channels that can be used as TCHs in the cell is 13. Because 13 x 2 >17 > 13, nine (2 x 13 - 17) channels in the cell should be configured as Techs. Other channelsin the cell are configured as TCHHs. The TCH Traffic Busy Threshold(%) is set to 70 (100x [2 x 13 - 17]/13). The AMR TCH/H Prior Cell Load Threshold must be smaller than theTCH Traffic Busy Threshold(%).

Based on ERLANG B, if the traffic volume in the cell is Z, the number of configured channelsis 28 and the number of channels that can be used as TCHs in the cell is 13. Because 28 > 13 x2, all the channels in the cell should be configured as TCHHs. At the same time, Huaweirecommends that a user should perform an expansion. The TCH Traffic Busy Threshold(%)is set to 0 and the AMR TCH/H Prior Cell Load Threshold is set to 0.

NOTE

The method of configuring the full-rate and half-rate channels described previously is simple. The supportcapability of MSs for the full-rate and half-rate channels and the channel assignment strategies are notconsidered. In fact, the call loss rate in a cell is related to these factors. Therefore, Huawei recommendsthat the method described previously be used as a rough estimation method. You need adjust the settingsof TCH Traffic Busy Threshold(%) and AMR TCH/H Prior Cell Load Threshold based on the trafficvolume.

12.4 CapabilitiesBSC6000V900R001C01 supports up to 2048 TRXs that can provide half-rate services.




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12.5 ImplementationThis describes how to configure half-rate services, verify half-rate services, activate the functionof reserving priority resources, adjust half-rate services, and deactivate half-rate services.

12.5.1 Configuring Parameters of Half-Rate ServicesConfigure the half-rate parameters through the BSC6000 Local Maintenance Terminal.

12.5.2 Verifying Half-Rate ServicesBased on different channels configured on TRXs, the verification methods are different.

12.5.3 Enabling the Function of Reserving Priority ResourcesEnable the function of reserving priority resources through the BSC6000 Local MaintenanceTerminal.

12.5.4 Reconfiguring Half-Rate ParametersReconfigure the half-rate parameters through the BSC6000 Local Maintenance Terminal.

12.5.5 Disabling Half-Rate ServicesDisable the half-rate services through the BSC6000 Local Maintenance Terminal.

12.5.1 Configuring Parameters of Half-Rate ServicesConfigure the half-rate parameters through the BSC6000 Local Maintenance Terminal.

Procedure

Step 1 Apply for and enable the license.

1. To apply for the license for the half-rate service, in the BSC6000V900R001 ExceptionalCommercial License Application Template, you should fill in the number of the TRXs thatsupport half-rate service in a specified range in the corresponding row of Number of theTRX supporting half-rate in the Resource control items column.

2. Activate the license on the BSC6000 Local Maintenance Terminal. For details, refer toActivating the BSC License.

After the license is activated, the BSC supports the half-rate service. However, you still need toset the attributes of related objects and parameters through the BSC6000 Local MaintenanceTerminal.

Step 2 Configure the half-rate speech version.

NOTE

The half-rate speech versions that the BSC supports consist of Half-rate Version 1, Half-rate Version 2,and Half-rate Version 3.

Half-rate Version 2 in speech versions configured through the BSC6000 Local Maintenance Terminalis reserved for protocols. Currently, no service of Half-rate Version 2 is available.

1. On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-click the target cell, and then choose Configure Cell Attributes on the shortcut menu. Adialog box is displayed, as shown in Figure 12-9.



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Figure 12-9 Configuring Cells Attributes dialog box (1)

2. Double-click the target cell in the Cell view list box to add it to the Selected cells list box.

3. Click Next. A dialog box is displayed, as shown in Figure 12-10.


4. In the Cells to be set area, select the target cell, and then click Set Cell Properties. A dialogbox is displayed, as shown in Figure 12-11.




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Figure 12-11 Setting Cell Attributes dialog box

5. Click Call Control. A dialog box is displayed, as shown in Figure 12-12.



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Figure 12-12 Setting call control parameters (1)

6. Click Advanced. A dialog box is displayed, as shown in Figure 12-13.




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Figure 12-13 Setting call control parameters (2)

7. Click the Access Control tab. On the tab page, set the value of Speech Version to SupportHalf-rate Version 1, as shown in Figure 12-14.

Figure 12-14 Setting speech versions

8. Click OK to return to the dialog box shown in Figure 12-11.9. Click OK to save the configuration of cell parameters. A previous dialog box is displayed,

as shown in Figure 12-10.10. Click Finish. The configuration is complete.

Step 3 Adjust the type of the TRX channel as "TCH Half Rate"



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NOTE

The standard of selecting the type of a channel is as follows:

l If the half-rate channels are configured fixedly, the type of the channel is adjusted as "TCH Half Rate."

l If the full-rate channels are configured fixedly, or the rate of channels can be dynamically adjusted,the type of the channels is adjusted as "TCH Full Rate."

If a TRX is not configured with the half-rate channels, and if the TRX supports the half-rate service, theTCH Rate Adjust Allow must be enabled.

A TRX channel is configured as "TCH Half Rate" to support the half-rate service. The detailedprocedures are as follows:

1. As shown in Figure 12-11, in the Assigned TRXs area, select a TRX to be adjusted. ClickTRX Config. A dialog box is displayed, as shown in Figure 12-15.

Figure 12-15 Configuring TRX attributes

2. Select Channel Attributes tab. On the tab page, select the channel number to be adjustedin the Channel No.[0] area. In the Channel Type drop-down list box, select the channeltype to be set, as shown in Figure 12-16.




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Figure 12-16 Configure TRX Attributes-TRX0 dialog box

3. Click OK. The configuration of the TRX parameters is complete.

Step 4 If a TRX does not have "TCH Half Rate" channels and only has "TCH Full Rate" channels, theTCH Rate Adjust Allow needs to be enabled to enable the TRX to support the half-rate service.

NOTE

For a TRX whose TCH Rate Adjust Allow is not enabled, channels on the TRX are assigned preferably.Therefore, the channels on the TRXs that support the rate adjustment can be reserved for further use. Theresources can be used maximally.

1. As shown in Figure 12-11, in the Assigned TRXs area, select a TRX to be adjusted. ClickTRX Config. A dialog box is displayed, as shown in Figure 12-15.

2. On the Device Attributes tab page, set the value of the TCH Rate Adjust Allow to Yes,as shown in Figure 12-17.



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Figure 12-17 Device attributes

3. Click OK. The configuration of the TRX parameters is complete.

----End

12.5.2 Verifying Half-Rate ServicesBased on different channels configured on TRXs, the verification methods are different.

Procedure

Step 1 The TRX is configured with a "TCH Half Rate" channel.

1. On the BSC6000 Local Maintenance Terminal, right-click a TRX on the ManagementTree tab page. Choose Monitor Channel Status from the shortcut menu. A dialog box isdisplayed, as shown in Figure 12-18.




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Figure 12-18 Monitor Channel Status(1) dialog box

2. Click Start. If a channel shown in Figure 12-19 is found, the TRX supports the half-rateservice.

Figure 12-19 Half-rate channel status

Step 2 The TRX is configured with only "TCH Full Rate" channels.

1. Use an MS that supports the half-rate service to lock the frequency in a cell where a TRXis located.

2. On the BSC6000 Local Maintenance Terminal, right-click a TRX on the ManagementTree tab page. Choose Monitor Channel Status from the shortcut menu. A dialog box isdisplayed, as shown in Figure 12-18.

3. Click Start and view the channel status.4. On the BSC6000 Local Maintenance Terminal, right-click a cell where the TRX is

located on the Management Tree tab page. Then choose Modify Administrative State.A dialog box is displayed, as shown in Figure 12-20.



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Figure 12-20 Modifying management status

5. Block all the other TCHs in the cell where the TRX is located so that a new speech serviceinitiated by an MS in the cell can only use TCHs that is on the TRX.

6. As shown in Figure 12-21, click Channel Management. A dialog box is displayed, asshown in Figure 12-22.




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Figure 12-22 Setting channel management parameters

7. Click Advanced. A dialog box is displayed, as shown in Figure 12-23.




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Figure 12-23 Set Channel Parameter[Cell:3002E] dialog box

8. Select the HWII Channel Assignment and Radio Channel Control tab. On the tab page,set the value of the TCH Traffic Busy Threshold(%) to 0.

9. Click OK. The configuration of parameters is complete.10. Initiate a new speech service in the cell.11. View Figure 12-18 to check whether the latest occupied channel on the TRX is a half-rate

channel. If the channel is a half-rate channel, the TRX supports the half-rate service.

----End

12.5.3 Enabling the Function of Reserving Priority ResourcesEnable the function of reserving priority resources through the BSC6000 Local MaintenanceTerminal.

Procedure

Step 1 Apply for and enable the license.

1. To apply for the license for the half-rate service, in the BSC6000V900R001 ExceptionalCommercial License Application Template, ensure that the Whether or not to activatethe Channel Reserved function in the Resource control items column is set to 1. Thatis, the function of reserving priority resources is enabled.

2. Activate the license on the BSC6000 Local Maintenance Terminal. For details, refer toActivating the BSC License.

After the license is activated, the BSC supports the function of reserving priority resources.However, the attributes of related objects and parameters need to be set through the BSC6000Local Maintenance Terminal.

Step 2 On the BSC6000 Local Maintenance Terminal, right-click a cell on the Management Treetab page, and choose Configure Cell Attributes from the shortcut menu. A dialog box isdisplayed, as shown in Figure 12-24.



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Step 3 Double-click the target cell in the Cell view list box to add it to the Selected cells list box.

Step 4 Click Next. A dialog box is displayed, as shown in Figure 12-25.


Step 5 In the Cells to be set area, select the target cell, and then click Set Cell Properties. A dialogbox is displayed, as shown in Figure 12-26.




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Step 6 In the Advanced Attributes area, click Channel Management. A dialog box is displayed, asshown in Figure 12-27.



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Figure 12-27 Set Channel Parameter[Cell: 3002E] dialog box

Step 7 Set the value of Grade Access Allow to Yes. Set the value of Highest Priority to 1. Set thevalue of Reserved Channel Number to 3. Click OK.

NOTEThe value of

Reserved Channel Type can be only TCH FULL RATE. This parameter does not need to be adjusted.

Step 8 Click OK. The Configuring Cells Attributes dialog box is displayed.

Step 9 Click Finish to complete enabling the function of reserving priority resources.

----End

12.5.4 Reconfiguring Half-Rate ParametersReconfigure the half-rate parameters through the BSC6000 Local Maintenance Terminal.

Context

The reconfiguration of the half-rate parameters mainly refers to the modification of the channelmanagement parameters in a cell.




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Procedure

Step 1 As shown in Figure 12-28, reconfigure the parameter, and then click OK.

Figure 12-28 Set Channel Parameter[Cell:3002E] dialog box

NOTE

As shown in Figure 12-28, the channel management parameters related to the half-rate service can beconfigured. Basic parameters consist of Grade Access Allow, Highest Priority, Reserved ChannelNumber, and Enhanced TCH Adjust Allowed. Advanced parameters consist of TCH Traffic BusyThreshold(%).

Step 2 Click OK to return to the dialog box shown in Figure 12-29.



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Step 3 Click OK to save the configuration of cell parameters. The previous dialog box is displayed, asshown in Figure 12-30.




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Step 4 Click Finish. The configuration is complete.

----End

12.5.5 Disabling Half-Rate ServicesDisable the half-rate services through the BSC6000 Local Maintenance Terminal.

ContextIf a site does not supply the half-rate service, a license that is applicable to the site and that doesnot support the half-rate service can be applied. For the disabling of the license, refer toMaintaining the BSC License.

If you need only disable the half-rate service for a TRX, you need modify only the TRX attributes.For detailed procedures, refer to the following:

Procedure

Step 1 On the BSC6000 Local Maintenance Terminal, right-click a TRX on the ManagementTree tab page. Choose Configure TRX Attributes from the shortcut menu. A dialog box isdisplayed, as shown in Figure 12-31.



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Figure 12-31 Configuring TRX attributes wizard

Step 2 In the TRX view area, select a TRX whose attributes is to be modified. Then, click Set TRXAttributes. A dialog box is displayed, as shown in Figure 12-32.

Figure 12-32 Configuring TRX attributes




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Step 3 Click Channel Attributes tab. On the tab page, select a channel number that can enable theChannel Type to be TCH Half Rate from the Channel No.[0]. In the Channel Type drop-down list box, choose TCH Full Rate, as shown in Figure 12-33.

Figure 12-33 Configure TRX Attributes-TRX0 dialog box

Step 4 On the Device Attributes tab page, set the value of the TCH Rate Adjust Allow to Yes orNo.

Step 5 Click OK. to return to the dialog box shown in Figure 12-31.

Step 6 Click Finish to complete the modification of TRX attributes.

----End

12.6 Maintenance InformationThis lists the performance counters related to the half-rate service.

Alarms

None.

Counters

Table 12-3 describes the performance measurement counters involved in the half-rate service.



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Table 12-3 Counters related to the half-rate service

Counter Description

H3023A Failed Internal Intra-Cell Handovers(Dynamic Conversion, TCHF-TCHH)

H3023B Failed Internal Intra-Cell Handovers(Dynamic Conversion, TCHH-TCHF)

H3003A Internal Intra-Cell Handover Requests(Dynamic Conversion, TCHF-TCHH)

H3003B Internal Intra-Cell Handover Requests(Dynamic Conversion, TCHH-TCHF)

H3013A Internal Intra-Cell HandoverCommands (Dynamic Conversion,TCHF-TCHH)

H3013B Internal Intra-Cell HandoverCommands (Dynamic Conversion,TCHH-TCHF)

TH3033A Success Rate of Internal Intra-CellHandover (Dynamic Conversion,TCHF-TCHH)

TH3033B Success Rate of Internal Intra-CellHandover (Dynamic Conversion,TCHH-TCHF)

CH3033A Successful Internal Intra-CellHandovers (Dynamic Conversion,TCHF-TCHH)

CH3033B Successful Internal Intra-CellHandovers (Dynamic Conversion,TCHH-TCHF)

R3505A Channel Conversion Requests (TCHF-TCHH)

R3525A Successful Channel Conversions(TCHH-TCHF)

R3505B Channel Conversion Requests (TCHH-TCHF)

R3525B Successful Channel Conversions(TCHH-TCHF)

R3529A Number of Successful ChannelConversions (PDCH to TCHH)

R3522A Number of Successful ChannelConversions (TCHH to PDCH)




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12.7 ReferencesNone.



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Documents

Half Rate Service