ud freq reconfig with min disturbance

Open InformationUSER DESCRIPTION 1 ( 16 )

EAB/RJZ/GTF Kjell Wikander 50/1553-HSC10312/4 Uen

EAB/RJZ/GTE (Ulrika Unell) 2003-01-17 A

Prepared (also subject responsible if other) No

Approved Checked Date Rev Reference

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User Description, Frequency Re-configuration withMinimum Disturbance

Contents Page

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Glossary .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Concepts .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Abbreviations and acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4 Technical description .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.2 Algorithm .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.3 Main changes in Ericsson GSM system R10/BSS R10 .. . . . . . . . . . . . . . . . . . . . . . 14

5 Engineering Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.1 Selection of Frequency Re-configuration Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6 Parameters .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.1 Main controlling parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.2 Value ranges and defaults values .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

7 References .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

A4 XSEIF R2






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1 Introduction

Frequency Re-configuration with Minimum Disturbance allows the following tobe performed with minimal disturbance to ongoing traffic within a cell:

addition of a frequency to a cell

change of frequency within a cell

automatic use of newly installed TRX

automatic use of recovered TRX

automatic HFS extension

2 Glossary

2.1 Concepts

BasebandHopping

A method of frequency hopping in which each transmitterserving a cell is configured to transmit on one frequency only.All transmitters serving a channel group or cell transmit ona different frequency. Frequency hopping is achieved bytransmitting each Basic Physical Channel from a differenttransmitter in successive TDMA frames.

BasicPhysicalChannel

A Basic Physical Channel (BPC) is a channel transmitted on theradio interface between the BTS and MS and occupying oneTime slot Number within each TDMA frame.

ChannelGroup

A channel group is a group of frequencies within one cell. A cellmay have one or more channel groups. A given frequency canappear in different channel groups in a cell.

HoppingFrequencySet

The set of frequencies over which the Basic Physical Channelswithin a Hopping Group are permitted to hop.

HoppingGroup

A group of Basic Physical Channels each transmitted fromdifferent transmitters serving the same cell, all occupying thesame Time slot Number in the air and all having the sameHopping Frequency Set. Refer to figure 1 .

HFSExtension

A mechanism that increases the number of frequencies within aHopping Frequency Set when one or more unused transmittersbecome available for use. When HFS Extension is complete, acell can support a greater number of Basic Physical Channelsand traffic capacity is increased.






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HFSreduction

A reduction of the number of supported frequencies withina Hopping Frequency Set. This may be because the cellspecification has changed so that the current configurationno longer supports the required HFS. Alternatively, one ormore transmitters supporting the HFS may have becomenon-operational. When HFS reduction has occurred then thecell can support fewer Basic Physical Channels and trafficcapacity is reduced.

SynthesizedHopping

A method of frequency hopping in which a Basic PhysicalChannel is transmitted by one transmitter only. Frequencyhopping is achieved by configuring all transmitters serving achannel group or cell to transmit on a different frequency insuccessive TDMA frames.

f1

f2

f3

BCCHf0

f4

f5

}}

CHGR 0

CHGR 1HFS 1

CHGR 2HFS 2

CHGR0 contains the BCCH only on f0

The circled groups of BPC indicate separate Hopping Groups (HG).CHGR2 hops over HFS2 comprising f5f4 and

f1CHGR1 hops over HFS1 comprising f2 f3, and

Figure 1 Relation between CHGR, HFS and HG

2.2 Abbreviations and acronyms

BCCH Broadcast Control Channel

BPC Basic Physical Channel






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BSC Base Station Controller

BTS Base Transceiver Station

CHGR Channel Group

GPRS General Packet Radio Service

HG Hopping Group

HFS Hopping Frequency Set

MS Mobile Station

SDCCH Standalone Dedicated Control Channel

TDMA Time Division Multiple Access

TG Transceiver Group

TRX Transceiver

TX Transmitter

3 Capabilities

The user can specify the re-configuration method to be used for eachTransceiver Group (TG). For all methods, frequency re-configuration isperformed with increased regard to maintaining existing traffic capacity. Theuser has the following options for each TG:

No BPCdeletion

No command ordered HFS Extension is possible for the TG.The benefit is that any command ordered HFS Extension cannotdisturb ongoing traffic carried by the TG.

Commandordered HFSExtension

A command ordered HFS Extension is possible for the TG. Thebenefit is that the user can order an HFS Extension during a lowtraffic period. Thus, existing traffic capacity is maintained anddisturbance of ongoing traffic is minimised.

Minimumdisturbance

Frequency re-configuration is performed immediately andautomatically. Disturbance of ongoing traffic is minimised.The benefit is that call revenue may increase and subscribersexperience improved reliability of ongoing calls.

FastestRecovery

Frequency re-configuration is performed immediately andautomatically. Maximum traffic capacity is achieved as fast aspossible. The benefit is that call revenue may increase andsubscribers experience improved access.






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4 Technical description

4.1 General

4.1.1 BackgroundConfiguration is a process applied automatically to one or more TransceiverGroup (TG) in response to the user defining and activating a cell. Configurationmeets the requirements of a cell specification by performing the following:

allocating unused BTS equipment of the appropriate capability to the cell

defining the radio network characteristics of the allocated BTS equipment

After successful configuration, BTS equipment is reserved for use by a cell andhas the radio network characteristics specified for the cell. The cell then meetsthe cell specification on the radio interface.

Re-configuration becomes necessary when (for any reason) the allocatedBTS equipment no longer meets the requirements of the cell. This can bebecause the user has changed the cell specification in a way that is no longersupported by the BTS equipment. Alternatively, if BTS equipment becomespermanently or temporarily faulty then the cell may no longer have the requiredradio network characteristics.

The benefit of Frequency Re-configuration with Minimum Disturbance ismostly seen in cells using Frequency Hopping. For a description of the benefitsof Frequency Hopping, refer to User Description, Frequency Hopping . Thepurpose of the feature is to minimise disturbance to ongoing traffic and maintaintraffic capacity in the event that re-configuration is necessary.

Cells using Synthesized Hopping are sensitive to changes in the HoppingFrequency Set (HFS) that result from addition or removal of frequencies withina Channel Group. The reason is that all Transmitters supporting the HoppingGroups in that Channel Group must then be re-configured to hop over thenew HFS.

Cells using Baseband Hopping are also sensitive to changes in the HFS butare particularly sensitive to reductions in the number of available Transmitters.This results from a permanent or temporary fault in a Transmitter that isserving the cell. The reason is that in Baseband Hopping all Basic PhysicalChannels (BPC) within one or more Hopping Groups make use of a number ofTransmitters. Consequently, if one Transmitter becomes faulty then the requiredre-configuration potentially disturbs many BPC.

4.1.2 Selection of Re-configuration MethodThere is a choice of re-configuration method for each TG. This is because adifferent method is appropriate depending on the cell specification. The useris able to specify the method to be used for each TG. This is because thepreferred method depends to some extent on operational policy. Refer toengineering guidelines in chapter chapter 5 . Each method results in a different






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re-configuration algorithm. The algorithms are described in chapter chapter4.2 .

Refer to table 1 . This indicates the selected re-configuration algorithmdepending on the specified re-configuration method and the reason why are-configuration is required. There are many reasons why re-configuration ofa TG may be required. Only those cases where HFS reduction is possible(and therefore HFS Extension is required) are indicated. In all other cases,re-configuration is always performed without HFS Extension.

Table 1 Selected Re-configuration Algorithm

Algorithm when Method is:Reason forre-configuration NODEL CMD FASTREC MINDISTHopping Groupdata changed

FastRecovery.AutomaticHFSExtension



MinimumDisturbance.AutomaticHFSExtension

BSC Restart FastRecovery.No HFSExtension

FastRecovery.No HFSExtension



TX becomesoperational





CommandOrdered HFSExtension

Notpermittedfor TG

HFSExtensiononly

Notpermittedor requiredfor TG

Not permittedor required forTG

Other reason. Inall cases, HFSExtension is notrequired.

FastRecovery

FastRecovery

FastRecovery

MinimumDisturbance

If the re-configuration method is NODEL and HFS reduction has occurred thenthe cell must be manually halted and then activated. Halting a cell results inloss of all ongoing traffic in the cell. Activating the cell starts Configuration.Configuration will then satisfy the cell specification in full if sufficient BTSequipment of the appropriate capability is available.

If the re-configuration method is CMD then an HFS Extension can be orderedmanually for the TG by BSC command. The cell does not need to be halted inthis case. A command ordered HFS Extension executes the HFS Extension






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part of the re-configuration only. If the re-configuration method is other thanCMD then a command ordered HFS Extension is not accepted for the TG.

Automatic HFS Extension means that HFS Extension is performed withoutrequiring manual intervention. The consequence is that the cell specification isalways satisfied in full if sufficient BTS equipment of the appropriate capabilityis available.

It can be seen that Automatic HFS Extension is always performed in the casethat the user has changed the Hopping Group data for a cell or channel group.The reason is that such a change always results in HFS reduction and sometraffic disturbance. Therefore, attempting HFS Extension is always worthwhile.Changes of Hopping Group data include: addition or removal of frequenciesfrom a channel group or cell already configured as frequency hopping; and anychange of hopping status for a channel group or cell.

In the cases of either a BSC Restart or a Transmitter becoming operational,HFS reduction may have occurred. In these cases, Automatic HFS Extensionis performed only if the specified re-configuration method is FASTREC orMINDIST .

4.2 Algorithm

This section describes the re-configuration algorithms used depending on themethod specified for a TG. The intention is to provide an overview and illustratethe differences between each method.

4.2.1 Common Aspects

There are a number of features common to all re-configuration methods.Re-configuration is always performed for one Transceiver Group (TG).Re-configuration of a cell is achieved by repeating re-configuration for all TGconnected to each Channel Group. A different re-configuration method canbe selected for each TG (if required). All Hopping Groups within a TG areprocessed. Each Hopping Group is re-configured before the next HoppingGroup is considered. Consequently, the number of BPC unavailable for traffic atany given time is minimised. Thus, disturbance to ongoing traffic is minimisedand traffic capacity is maintained where possible.

4.2.2 Minimum Disturbance and Fastest Recovery

Refer to figure 2 and figure 3 . These illustrate the algorithms used by there-configuration methods MINDIST and FASTREC respectively.






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No

For each surplus BPC in Hopping Group

Yes

2. Is there an unused Transmitter thatcan satisfy the Hopping Frequency Set? No

4. If a busy traffic channel then attemptintra-cell handover. If not possible then attempt handover to a neighbouring cell.

3. Make idle BPC unavailable for new calls.

For each Hopping Group within the TG

1. Is the required Hopping Frequency Set reduced?

Yes

5. Configure BTS equipment to support Hopping Group.

7. All Hopping Groups within TG configured?

6. Make all configured BPC available for new calls. Wait for all BPC to become available.

NoYesFinish


Automatic HFS Extension.

Figure 2 Re-configuration with Minimum Disturbance






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1. Is the required Hopping Frequency Set reduced?


No

No

4. If a busy traffic channel then attempt handoverto a neighbouring cell. If not possible thenattempt intra-cell handover.

3. Make idle BPC unavailable for new calls.

For each Hopping Group within the TG

Yes

Yes

2. Is there an unused Transmitter thatcan satisfy the Hopping Frequency Set?

6. Configure BTS equipment to support Hopping Group.

7. Make all configured BPC available for new calls. Do not wait for all BPC to become available.

No

Finish

8. All Hopping Groups within TG configured?

Yes

Automatic HFS Extension

Figure 3 Re-configuration with Fastest Recovery

For each Hopping Group, the algorithm considers if the Hopping Group isHopping Frequency Set (HFS) reduced. This means that the HFS for theHopping Group is not satisfied. This may be the case because, for example,a Transmitter being used by the Hopping Group is no longer operational.Alternatively, the user may have added or changed a frequency within the cell.






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If the Hopping Group is HFS reduced then the algorithm considers if there is aTransmitter available that would satisfy the HFS. This may be an operationalTransmitter that is currently not in use (unconfigured) or is configured to afrequency no longer required.

If a Transmitter is available that can satisfy the HFS then the algorithmconsiders for each BPC in the Hopping Group whether it is still required orwhether it is surplus. A BPC is considered surplus if it no longer supports thecurrent cell specification or is not required by the current cell specification.

The BPC carrying the BCCH for the cell is only considered surplus if the userhas specified a change of BCCH frequency or if the transmitter that is carryingthe BCCH is no longer operational. In all other cases, the BPC carrying theBCCH is unaffected. This ensures that ongoing traffic is undisturbed andnew calls can be set up in the cell.

If (exceptionally) a BPC carrying an SDCCH needs to be removed then thechannel must be released on the radio interface. The unavoidable consequenceis that (for a short period) no new calls can be established in the cell until a newBPC is re-configured with an SDCCH.

If the re-configuration method is MINDIST then all surplus and idle (non-trafficcarrying) BPC within the Hopping Group are made unavailable for new calls. Asecond pass of the Hopping Group is then made. If a surplus BPC is carrying abusy traffic channel then the BSC performs an intra-cell handover. If no idleBPC are available within the serving cell then the BSC attempts a handover toa neighbouring cell. If a suitable BPC is not available in a neighbouring cellthen the MS is ordered to release the channel on the radio interface and thecall is unavoidably lost. An intra-cell handover is always attempted first as thisresults in minimum disturbance to the call. Once a given Hopping Group hasbeen re-configured then there is a high probability that idle BPC are available tosatisfy handovers performed for BPC within the next Hopping Group. Idle andbusy BPC are considered in separate passes of each Hopping Group. Thisallows an intra-cell handover to be performed without the possibility of multiplehandovers of the same call.

If the re-configuration method is FASTREC then all surplus BPC (idle andbusy) are considered in one pass of the Hopping Group. Consequently,re-configuration is completed in less time relative to method MINDIST . An idleBPC is made unavailable for new calls. If a surplus BPC is carrying a busytraffic channel then the BSC attempts a handover to a neighbouring cell. If asuitable BPC is not available in a neighbouring cell then the BSC performs anintra-cell handover. If no idle BPC are available within the serving cell then theMS is ordered to release the channel on the radio interface and the call isunavoidably lost. A handover to neighbouring cell is always attempted first.This allows all BPC to be considered in a single pass of the Hopping Groupwithout the possibility of multiple handovers of the same call.

Once all surplus BPC in the Hopping Group are idle and unavailable fornew calls then the BTS is re-configured. The appropriate BTS equipmentis configured according to the current cell specification and to support therequired HFS of the Hopping Group.






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Once the required BTS equipment is configured then all BPC previously madeunavailable are now made available again to new calls. This process takessome time to execute in the BSC. If the re-configuration method is MINDISTthen the BSC waits for this process to complete before considering the nextHopping Group. The benefit is that the number of BPC unavailable for callsat any given time is minimised at the expense of slower recovery of full TGcapacity. Additionally, there is an increased probability that idle BPC will beavailable for an intra-cell handover when the next Hopping Group is processed.This reduces the risk of disturbance to ongoing calls. If the re-configurationmethod is FASTREC then the BSC does not wait for all BPC to becomeavailable before considering the next Hopping Group. The benefit is that themaximum possible TG capacity is recovered as fast as possible at the expenseof reduced capacity during the re-configuration.

Re-configuration is repeated Hopping Group by Hopping Group until allHopping Groups served by the TG are configured. The benefit is that onlyone Hopping Group is affected at a time so the number of calls actually orpotentially disturbed is minimised. Also, each Hopping Group supports therequired HFS in full before the next Hopping Group is considered. This isreferred to as Automatic HFS Extension. The benefit is that the maximumpossible traffic capacity is achieved automatically without requiring userintervention. Additionally, the available traffic capacity is maximised at all timesduring the re-configuration.

4.2.3 Other methods

The re-configuration methods NODEL and CMD use an equivalent algorithm tothat of FASTREC with the difference that automatic HFS Extension is usuallynot performed (refer to chapter chapter 4.1.2 ).If automatic HFS Extension is not performed then one or more Hopping Groupsserved by the TG are left HFS reduced. The consequence is that one or moreBPC are unavailable for traffic and the traffic capacity of the cell is reduced.

If the re-configuration method is CMD then the user is able to manually orderan HFS Extension by command. In this case, the resulting re-configurationperforms only the HFS Extension part of the algorithm used by methodFASTREC .

4.2.4 Working Example

Refer to figure 4 . This illustrates how the re-configuration algorithm affectsone Channel Group for a typical working example.






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HG0 HG1 HG2 HG3 HG 4 HG5 HG6 HG7

BCCH

TCH

TCH

TCH

TCH

TCH

TCH

SDCCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH TX0

TX1

TX2

f0

f1

f2

f3

.

BCCHf0

f1

f2

f3

TCH

TCH

TCH

TCH

TCH

TCH

SDCCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH TX0

TX1

TX2

TX3

Frequency is replaced by f4After re-configuration of the first HG, HG0 is HFS reduced due to unavailabilityof a TX transmitting on frequency f4

f4

BCCHf0

f1

f2

f3

TCH

TCH

TCH

TCH

TCH

SDCCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH TX0

TX1

TX2

TX3

HG0 HG6to are HFS reduced.After re-configuration of all HG, There is automatic HFS extension of HG7 to include frequency

BCCHf0

f1

f2

f4

TCH

TCH

SDCCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH TX0

TX1

TX2

TX3

After the second pass of re-configuration, there is automatic HFS extension of HG0 6HGto All BPC are available and hopping over frequency f4

f4 TX3






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Figure 4 Automatic HFS extension at change of frequency in cell

The case illustrated by figure 4 is for a TG providing four transmitters only (TX 0to TX 3 ), having one connected Channel Group and configured for BasebandFrequency Hopping over four frequencies (f 0 to f 3 ). The described behaviouris applicable to all re-configuration methods.

If a TG has unused transmitters available then re-configuration can becompleted after only one pass of the algorithm per Hopping Group. In thisexample, all transmitters are utilised. Therefore, a second pass of the algorithmis required. This is explained below.

The first diagram of figure 4 shows the situation before the re-configuration isstarted. The TG supports 8 Hopping Groups hopping over four frequenciesand all BPC are available. In this example, the user has removed frequency f 3from the connected Channel Group and added frequency f 4 . This results ina re-configuration due to the change of required hopping frequencies. In thiscase, Automatic HFS Extension is always performed irrespective of selectedre-configuration method.

Re-configuration is performed for the first Hopping Group (HG o ). All BPC in theHopping Group are considered surplus and made unavailable for new calls. TheBCCH is not affected because it is non-hopping and the user has not changedfrequency f 0 . Handovers are performed for any ongoing calls supported bythe Hopping Group. The transmitters TX 0 to TX 2 are re-configured and theBPC transmitted by these TX are made available for new calls. During this time,transmitter TX 3 is still transmitting on frequency f 3 and is unavailable becauseit is required to serve the remaining Hopping Groups. Therefore, HG 0 is HFSreduced. This is the instance in time illustrated by the second diagram of figure4 . The BPC marked with a cross is unavailable for traffic at this time.

Re-configuration is repeated for HG 1 to HG 6 . Consequently, HG 0 to HG 6 areall HFS reduced. When HG 7 is considered then TX 3 can be configured withfrequency f 4 and the required HFS is supported for this Hopping Group. Thisis the instance in time illustrated by the third diagram of figure 4 . The BPCmarked with a cross are unavailable for traffic at this time due to HFS reductionof their Hopping Group.

A second pass of the algorithm is now performed. All BPC (with the exceptionof that carrying the BCCH) in HG 0 to HG 6 are considered surplus and madeunavailable for traffic (once more). This is because these BPC must bere-configured with the new HFS. However, the last BPC in each of the first 6Hopping Groups can now be supported by TX 3 . Therefore, all BPC can bere-configured and made available for traffic. Thus, the second pass achievesAutomatic HFS Extension for the remaining Hopping Groups. Finally, full trafficcapacity is restored with all BPC baseband hopping over the new frequency f 4 .This is the situation illustrated by the fourth diagram of figure 4 .






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4.3 Main changes in Ericsson GSM system R10/BSS R10

No major changes. Channel group concept updated to reflect that the samefrequency can be used in different channel groups in R10.

5 Engineering Guidelines

For engineering guidelines regarding use of Frequency Hopping in a cell, referto User Description, Frequency Hopping .

5.1 Selection of Frequency Re-configuration Method

The methods NODEL and CMD are the basic options. The methodsFASTREC and MINDIST are introduced as enhancements and are generallyrecommended. The reason is that these methods maintain the maximumpossible traffic capacity at all times without requiring manual intervention. Ifthese methods are selected then subscribers experience improved connectionreliability and access. Consequently, increased call revenues can be expected.

The same re-configuration method may be specified for all TG served by a BSCor different methods may be specified separately for each TG. One approachis to specify the same (preferred) method for all TG and then examine theappropriate traffic counters to determine whether a different method would bemore effective in specific cells. It is recommended that the same method isspecified for all TG connected to a given cell. The reason is that it is then easierto interpret the traffic counters for a cell. For a description of the appropriatetraffic counters refer to User Description, Radio Network Statistics .

The recommended method for a given TG depends on the following factors:

whether Frequency Hopping is used in a cell

whether Baseband or Synthesized Hopping is used in a cell

traffic usage of cell and neighbouring cells

whether connection reliability of ongoing calls is a priority

whether improved access for new calls is a priority

If no Frequency Hopping or only Synthesized Hopping is used in a cell then allmethods of re-configuration have a similar affect on traffic capacity. Specifically,a maximum of 8 BPC are affected for each Transmitter to be re-configured. Ifno Frequency Hopping is used in a cell then no benefit is seen from AutomaticHFS Extension.

A cell using Baseband Hopping is particularly sensitive to faulty Transmitters. Afault in one Transmitter affects all BPC in all Hopping Groups served by thatTransmitter. If a cell uses Baseband Hopping then methods FASTREC and






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MINDIST are recommended. The reason is that traffic capacity is recoveredautomatically following recovery of a faulty Transmitter.

If a cell and its neighbouring cell are typically congested (have high trafficusage) then the method FASTREC may be preferable to MINDIST . The reasonis that for both methods any attempts to hand over ongoing calls will typically faildue to lack of idle capacity. Therefore, the benefits of MINDIST are not realisedand the method FASTREC recovers maximum traffic capacity more quickly.

If connection reliability of ongoing calls is a priority in a cell then the methodMINDIST is recommended. This priority may be appropriate for a cell withlow or average traffic usage.

If improved access for new calls is a priority in a cell then the method FASTRECis recommended. This priority may be appropriate for a cell with higher thanaverage traffic usage.

If a significant proportion of calls in a cell carry GPRS traffic then the methodFASTREC is recommended. The reason is that GPRS traffic is tolerant ofpoor connection reliability but benefits considerably from improved accessand capacity.

In summary, if the user has no preference for improved access over connectionreliability then method MINDIST is generally recommended (as indicated intable 2 ). The reason is that MINDIST results in negligible disturbance to alltraffic (outside the peak traffic period) where as FASTREC is mainly of benefitduring the peak traffic period.

6 Parameters

6.1 Main controlling parameters

CONFMD indicates the method of frequency re-configuration to be used withina Transceiver Group. All methods of frequency re-configuration are performedwith regard to maintaining existing traffic capacity. All methods attempt topreserve ongoing calls.

CONFMD=NODEL indicates that no BPC can be deleted as a result of acommand ordered HFS Extension. A command ordered HFS Extension is notpermitted for the TG. No HFS Extension is performed when previously faultyBTS equipment recovers. Consequently, recovered BTS equipment may notbe fully utilised.

CONFMD=CMD indicates that a command ordered HFS Extension can beperformed for the TG. No HFS extension is performed when previously faultyBTS equipment recovers. Consequently, recovered BTS equipment may not befully utilised. If an HFS Extension is ordered by command then all availableBTS equipment (where required) is fully utilised.






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CONFMD=MINDIST indicates that disturbance of ongoing traffic is minimised.HFS Extension is performed automatically and immediately when required.

CONFMD=FASTREC indicates that maximum traffic capacity is recovered asfast as possible. HFS Extension is performed automatically and immediatelywhen required.

6.2 Value ranges and defaults values

Table 2 All Parameters

Parameter name Defaultvalue

Recommendedvalue

Value range Unit

CONFMD NODEL MINDIST NODEL, CMD,MINDIST,FASTREC

7 References

1 User Description, Frequency Hopping2 User Description, Radio Network Statistics

ud freq reconfig with min disturbance

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