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10 EFRAbout This Chapter

10.1 Overview

This topic describes the definition and purposes of EFR.

10.2 Availability

The realization of EFR depends on the cooperation of related NEs and software.

10.3 Technical Description

This topic describes the EFR call establishment procedure and the EFR call signaling processing

procedure.

10.4 Implementation

The implementation of EFR refers to configuring EFR.

10.5 Maintenance Information

The maintenance information of EFR refers to related counters.

10.6 References

HUAWEI BSC6000 Base Station Subsystem

BSS Feature Description 10 EFR

Issue 01 (2007-09-05) Huawei Technologies Proprietary 10-1

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10.1 Overview

This topic describes the definition and purposes of EFR.

Definition

Enhanced Full Rate (EFR) is a type of speech coding scheme.

Purposes

EFR optimizes the speech quality for the subscribers.

Terms

None.

Abbreviation

Abbreviation Full Spelling

EFR Enhanced Full Rate

TDMA Time Division Multiple Access

10.2 Availability

The realization of EFR depends on the cooperation of related NEs and software.

Network Elements Involved

Table 10-1 lists the network elements involved in EFR.

Table 10-1 NEs involved in EFR

MS BTS BSC MSC MGW SGSN GGSN HLR

NOTE

l -: not involved

l : involved

Software Releases

Table 10-2 describes the software versions of GBSS products that support EFR.

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BSS Feature Description

10-2 Huawei Technologies Proprietary Issue 01 (2007-09-05)

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Table 10-2 GBSS products and related versions

Product Version

BSC BSC6000 V900R001 and later releases

BTS BTS3X All releases

BTS3002C All releases

BTS3001C Not supported

BTS3012 All releases

BTS3012AE All releases

BTS3006C All releases

Miscellaneous

None.

10.3 Technical Description

This topic describes the EFR call establishment procedure and the EFR call signaling processing

procedure.

10.3.1 EFR Call Establishment Procedure

This topic describes the EFR call establishment procedure.

10.3.2 EFR Call Signaling Processing Procedure

This topic describes the EFR call signaling processing procedure.

10.3.1 EFR Call Establishment Procedure

This topic describes the EFR call establishment procedure.

During the call establishment procedure, the BSC receives the assignment request from the MSC,

and decides whether the call supports EFR based on the speech version that the MSC allows and

the circuit pool number of the circuit. When the speech version carried in the Assignment Request

message is full-rate speech version 2 (EFR), and when the circuit pool implied by the CIC

information element supports EFR, the call is an EFR call. In other cases, a common call isestablished.

Figure 10-1 shows the EFR call establishment procedure.




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Figure 10-1 EFR call establishment procedure

Yes

No

Start

Speech versioncarried in the assignment

request is EFR

Circuit pool

implied by

the CIC information

element supportsEFR?

EFR call

A common cal l (FR)

End

EFR uses the CELP linearcoding scheme to optimize the speech quality. EFR is implemented

through the GDPUC software of the BSC and the DSP software of the BTS. The BSC host

software and OMC software provide some auxiliary functions.

When the EFR is applied in the GSM network, the transmission rate of speech signals transmittedby an MS is 12.2 kbit/s.

10.3.2 EFR Call Signaling Processing Procedure

This topic describes the EFR call signaling processing procedure.

Figure 10-2 shows the EFR call signaling processing procedure.

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Figure 10-2 EFR call signaling procedure

MS BTS BSC

Assignment

Request (1)

Channel Activation (2)

Channel ActivationAcknowledge

Assignment Command

SABM

UA

Establishment Indication

Assignment Complete (3)

Assignment

Complete

Start T3107

Stop T3107

Main DCCH

FACCH

FACCH

FACCH

Start T10

Stop T10

MSC

1. The MS sends the MSC a Setup message to indicate whether the MS supports EFR. Based

on the service type of the call, the MSC sends an Assignment Request message carrying

the speech version to the BSC.

2. The BSC decides whether the call supports EFR, based on the speech version allowed by

the MSC and the circuit pool to which the circuit belongs. If the call supports EFR, the

BSC sends a Channel Activation message to the BTS carrying the full-rate speech version

2 (EFR) in the channel mode. After the BTS responds with a Channel Activation

Acknowledge message, the BSC sends an Assignment Command message to the MS

carrying the full-rate speech version 2 (EFR) in the channel mode.3. The MS reports an Assignment Complete message to the BSC, and the BSC sends the

Assignment Complete message to the MSC. The EFR call establishment procedure is

complete.

10.4 Implementation

The implementation of EFR refers to configuring EFR.

10.4.1 Configuring EFR

This topic describes how to configure the EFR on the BSC6000 Local MaintenanceTerminal.




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10.4.1 Configuring EFR

This topic describes how to configure the EFR on the BSC6000 Local Maintenance

Terminal.

Procedure

Step 1 On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-clickthe target cell and then choose Configure Cell Attributes on the shortcut menu. A dialog box

is displayed, as shown in Figure 10-3.

Figure 10-3 Configuring Cells Attributes dialog box (1)

Step 2 Double-click the target cell in the Cell view area to add the cell to the Selected cells area.

Step 3 ClickNext. A dialog box is displayed, as shown in Figure 10-4.

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Figure 10-4 Configuring Cells Attributes dialog box (2)

Step 4 In the Cells to be set area, select the target cell and then clickSet Cell Properties. A dialog boxis displayed, as shown in Figure 10-5.




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Figure 10-5 Set Cell Attributes dialog box

Step 5 ClickCall Control. A dialog box is displayed, as shown in Figure 10-6.

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Figure 10-6 Set Channel Parameter dialog box

Step 6 ClickAdvanced. A dialog box is displayed, as shown in Figure 10-7.




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Figure 10-7 Set Call Control Parameter dialog box

Step 7 Click the Access Control tab. On the tab page, set the value ofSpeech Version to SupportFull-rate Version 2, as shown in Figure 10-8.

Figure 10-8 Set Call Control Parameter dialog box

Step 8 ClickOKto return to the dialog box shown in Figure 10-5.

Step 9 ClickOKto save the configuration of cell attributes. A previous dialog box is displayed, asshown in Figure 10-4.

Step 10 ClickFinish. The configuration of cell attributes is complete.

----End

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10.5 Maintenance Information

The maintenance information of EFR refers to related counters.

Alarms

None.

Counters

Table 10-3 lists the performance counters involved in EFR.

Table 10-3 Counters involved in EFR

Counter DescriptionA3167B: Speech version 2 completed

assignments (excluding directed retry)

(TCHF)

This counter indicates the number of the

Assignment Complete messages adopting the

full-rate speech version 2 that are sent by the MS.

It is a cell-level counter.

10.6 References

l GSM 08.08 version 7.6.1: "Digital cellular telecommunications system (Phase 2+)"






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