zte umts amr-nb and amr-wb feature description

AMR-NB & AMR-WB WCDMA RAN Feature Description

AMR-NB & AMR-WB Feature Description

ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. I

AMR-NB & AMR-WB Feature Description Version Date Author Approved By Remarks

V2.5 2009-1-20 Zhang jing Guo tian

V3.0 2009-2-27 Zhang jing Guo tian

© 2008 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information of the document is subjected to change without notice.


ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. II

TABLE OF CONTENTS 1 Functional Attribute ................................................................................................... 1

2 Overview ..................................................................................................................... 1 2.1 Function Introduction ................................................................................................... 1 2.1.1 ZWF21-02-001 CS AMR Voice and Session Service Bearer ..................................... 3 2.1.2 ZWF21-02-020 AMR-WB Voice Service ..................................................................... 3 2.1.3 ZWF21-04-005 Dynamic AMR Adaptation .................................................................. 3 2.1.4 ZWF21-06-002 TrFO Support ..................................................................................... 4

3 Technical Description................................................................................................ 5 3.1 CS AMR Voice and Session Service Bearer............................................................... 5 3.1.1 Implementation Mechanism of ZTE CS AMR Voice and Session Service Bearer

Function ....................................................................................................................... 5 3.1.2 Signaling Flow of AMR Service ................................................................................... 6 3.2 AMR-WB Voice Service............................................................................................... 7 3.2.1 Implementation Mechanism of ZTE AMR-WB Functions............................................ 7 3.3 Dynamic AMR Adaptation ........................................................................................... 9 3.3.1 Classification of Dynamic AMR Adaptation ................................................................. 9 3.3.2 Dynamic AMR Adaptation Based on Single-Link Transmission Power .................... 10 3.3.3 Dynamic Adjustment Triggered by Resource Congestion ........................................ 13 3.3.4 Dynamic Adjustment Triggered by Load ................................................................... 13 3.4 TrFO Support............................................................................................................. 13 3.4.1 OoBTC Outband Codec Control................................................................................ 14 3.4.2 IuUP Initialization ....................................................................................................... 15 3.4.3 IuUP Rate Control...................................................................................................... 15

4 Parameters and Configuration ............................................................................... 17 4.1 Parameter List of AMR Dynamic Rate Adjustment ................................................... 17 4.2 Configuration of AMR Dynamic Rate Adjustment Parameters.................................. 17

5 Counter and Alarm................................................................................................... 20 5.1 Counter List ............................................................................................................... 20 5.2 Alarm List ................................................................................................................... 20

6 Glossary .................................................................................................................... 20


ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. III

Figures and Tables Figure 1 Signaling Flow of AMR Service ..................................................................................... 6 Figure 2 UE Transmission Power Measurement Event Report................................................. 11 Figure 3 NodeB DTCP Measurement Event Report.................................................................. 12 Figure 4 Flow of OoBTC Outband Codec Control ..................................................................... 15 Figure 5 IuUP Initialization ......................................................................................................... 15 Figure 6 Flow of IuUP Rate Control ........................................................................................... 16

Table 1 AMR-NB Rate Classification.......................................................................................... 2 Table 2 AMR-WB Rate Classification......................................................................................... 2 Table 3 Parameter List.............................................................................................................. 17 Table 4 DPCH Maximum DL Power Default Value .................................................................. 19


ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. 1

1 Functional Attribute System version: [V08R2]

Attribute: [Optional]

NEs involved: UE NodeB RNC MSCS MGW SGSN GGSN HLR √ - √ √ √ - - √ Note: *-: No NE is involved. *√: An NE is involved.

Dependency: [None]

Mutual exclusion: [None]

Remarks: [None]

2 Overview

2.1 Function Introduction The present 3GPP employs narrowband AMR (AMR-NB) and wideband AMR (AMR-WB). For the AMR-NB, the speech channel bandwidth is limited to 3.7 MHz, and the sampling frequency is 8,000 Hz. For the AMR-WB, the speech channel bandwidth is up to 7 MHz, and the sampling frequency is up to 16,000 Hz. The AMR-WB has better speech quality than the AMR-NB, although the two modes have the same frame length of 20ms.

AMR is introduced into the 3G system based on the following considerations:

• By means of the AMR Control (AMRC), voice rate can be reduced to improve voice quality. In addition, system load can be effectively lightened. In the case of certain radio load, if users want to obtain the optimal subjective feeling of voice quality, the most suitable AMR is not the maximum rate, but a suitable medium rate. By weighing load, the AMRC can achieve the following goals:

− The AMRC can reduce an AMR when load is heavy. This lightens system load and improves voice quality.

− The AMRC can increase an AMR when load is light. In this way, QoS is greatly improved.

• When uplink coverage is limited, AMR can be reduced to effectively widen uplink coverage. In initial WCDMA network construction, both uplink coverage and



downlink capacity are limited; therefore, it is especially important to widen uplink coverage.

The Adaptive Multi-Rate (AMR) is also called the AMR-NB (Narrowband). This service has three service RBs, and can provide eight speech rates and two mute rates, as shown in Table 1 :

Table 1 AMR-NB Rate Classification

AMR Codec Mode

Total Number of Bits

Sub-flow 1

Sub-flow 2

Sub-flow 3

Codec Mode

AMR 4.75 kbps 95 42 53 0 AMR_4.75 AMR 5.15 kbps 103 49 54 0 AMR_5.15 AMR 5.9 kbps 118 55 63 0 AMR_5.90 AMR 6.7 kbps 134 58 76 0 AMR_6.70 AMR 7.4 kbps 148 61 87 0 AMR_7.40 AMR 7.95 kbps 159 75 84 0 AMR_7.95 AMR 10.2 kbps 204 65 99 40 AMR_10.20 AMR 12.2 kbps 244 81 103 60 AMR_12.20 AMR SID 39 39 0 0 AMR_SID GSM-EFR SID 43 43 0 0 GSM-EFR SID

*SID (Silence Descriptor)

AMR-NB voice coding is divided into three sub-flows out of consideration for the importance of information and error tolerance in voice coding. Each sub-flow requires its own QoS assurance. Sub-flow 1 is the most important. Sub-flow 2 comes next. Sub-flow 3 is the least important. Sub-flow 1 needs better channel coding at an air interface to guarantee its accuracy. No data rate is the coding in the case of mute. SID uses this frame to indicate that current voice is not activated.

AMR-WB is short for Adaptive Multi-Rate Wideband. This service was introduced in 1999 in order to provide better speech quality and speech reproducibility. It can be applied both in 3G system and GSM system.

Unlike AMR-NB, the AMR-WB has only two service RBs and provides nine speech rates and one mute rate, as shown in the Table 2 below:

Table 2 AMR-WB Rate Classification

AMR-WB Codec Mode


Sub-flow 1

Sub-flow 2

Sub-flow 3

Codec Mode

1.75 40 0 40 0 AMR-WB_SID* 6.60 132 54 78 0 AMR-WB_6.60 8.85 177 64 113 0 AMR-WB_8.85 12.65 253 72 181 0 AMR-WB_12.65 14.25 285 72 213 0 AMR-WB_14.25



AMR-WB Codec Mode


Sub-flow 1

Sub-flow 2

Sub-flow 3

Codec Mode

15.85 317 72 245 0 AMR-WB_15.85 18.25 365 72 293 0 AMR-WB_18.25 19.85 397 72 325 0 AMR-WB_19.85 23.05 461 72 389 0 AMR-WB_23.05 23.85 477 72 405 0 AMR-WB_23.85

*SID (Silence Descriptor)

Like the AMR-NB, the AMR-WB sub-flow 1 contains the most important information of speech, with 12-bit CRC protection added on the air interface. The sub-flow 2 contains less important speech information, without CRC protection on the air interface.

2.1.1 ZWF21-02-001 CS AMR Voice and Session Service Bearer

ZTE equipment supports all the eight AMRs: 12.2kbps, 10.2kbps, 7.95kbps, 7.4kbps, 6.7kbps, 5.9kbps, 5.15kbps, and 4.75kbps. What rate (s) to be used is same as the rate(s) in RAB Assignment from CN. ZTE equipment supports DTX and SID.

The RAB parameters of ZTE RAN equipment, used to bear session AMR services, follow the definition in the 3GPP TS 34.108.

2.1.2 ZWF21-02-020 AMR-WB Voice Service

ZTE RAN equipment supports all the nine speech rates of WB-AMR session, that is, 23.85Kbps, 23.05Kbps, 19.85Kbps, 18.25Kbps, 15.85Kbps, 14.25Kbps, 12.65Kbps, 8.85Kbps, 6.6Kbps, together with the mute rate 1.75 Kbps. What rate-(s) to be used is same as the rate(s) in RAB Assignment from CN.

ZTE RNC does not support RAB negociation between AMR-NB and AMR-WB. When the AMR-WB can not be established because of resources congestion, it is not supported to establish AMR-NB by RAB negociation.

The RAB parameters of ZTE RAN equipment, used to bear session AMR-WB services, follow the definition in the 3GPP TS 34.108.

2.1.3 ZWF21-04-005 Dynamic AMR Adaptation

In WCDMA system, the radio environment between UE and a base station always changes. When a UE is far away from the base station or the radio environment degrades, the base station or UE is bound to transmit at a higher power under the action of closed-loop power control in order to guarantee the QoS of AMR service. The power change and power increase at this time may result in sharp increase in power and further deterioration of the radio environment. As a result, the system capacity decreases. Even when the power is increased to even a certain limit value, QoS requirements of service can not be satisfied.



ZTE RNC equipment can monitor the uplink transmission power of UE in a UE internal measurement report or the downlink transmission power of a Node B dedicated measurement report base station. When the uplink or downlink transmission power rises to a certain threshold, the RNC will automatically adjust this user's AMR to reduce the power necessary for service. That is, a conversation is most probably kept going by reducing voice quality. When the radio environment between UE and the base station is good and the transmission power of the base station or UE decreases to a certain threshold, AMR can be increased to provide users with better voice quality as long as other users' feeling and system performance are not affected.

In addition, when a cell evaluated by means of downlink transmission power and uplink interference has high downlink load and uplink load, ZTE RNC equipment can lighten the cell load by reducing the AMR of some low-priority users, so as to accommodate more users.

The actual AMR which can be adjusted by the RNC must belong to the AMR code set configured for users by the CN during call establishment. The voice quality when low-rate AMR coding is used is not as good as that when high-rate AMR coding is used, but low-rate AMR coding has higher capacity (number of users) and wider coverage than high-rate AMR coding. Analysis of simulation result shows that there is about 30% coverage radius gain when the lowest AMR (4.75Kbps) instead of the highest AMR (12.2Kbps) is used. When the lowest AMR is used, a cell will accommodate twice as many users as those when the highest AMR is used.

2.1.4 ZWF21-06-002 TrFO Support

WCDMA employs AMR compressed voice encoding. The maximum encoding rate is 12.2kbit/s. At the R99 stage, TDM bearer is used between CS core network devices, and voice must employ 64kbit/s PCM encoding. One very important function of the R99 MSC is voice Transcoder (TC), which converts the AMR voice codes of a mobile terminal into PCM codes and transmits them over a network. The calls between mobile users require two voice encoding/decoding conversions, that is, AMR-PCM-AMR. Frequent encoding/decoding reduces voice quality.

In view of this, the 3GPP organization has introduced the Tandem Free Operation (TFO) and Transcoder Free Operation (TrFO) in the R4 protocol to avoid voice encoding/decoding. Meantime, the TFO and TrFO help save the transmission network bandwidth between core networks. The differences between both technologies are as follows: The TFO still needs TC resource. After call establishment, a direct connection is established between the TCs of the calling and called MSCs by means of in-band signaling negotiation to bypass encoding/decoding. The TrFO does not need any TC resource at all. It means that outband signaling encoding/decoding function (OoBTC) is used during call establishment to implement consistent voice encoding/decoding negotiation between UE and network.

The TFO technology is implemented in the core network equipment. It does not need the participation of RAN equipment. The TrFO technology requires that RAN equipment should support outband voice encoding negotiation and the processing related to a user plane. Both the TFO and TrFO can be used for AMR-WB encoding.

ZTE RAN equipment supports the TrFO function and complies with the 3GPP TS 23.153 and TS 25.415.



3 Technical Description

3.1 CS AMR Voice and Session Service Bearer

3.1.1 Implementation Mechanism of ZTE CS AMR Voice and Session Service Bearer Function

3.1.1.1 Set of CS AMR Voice and Session Service Bearer Functions Implemented by ZTE

• Selection of AMR-NB Rates

Function description: The 3GPP protocol defines eight speech rates and two mute rates for AMR-NB, which supports the speech rate up to 12.2k. A database saves all the rate configuration combinations of AMR-NB. According to the maximum rate of AMR-NB in a CN assignment message, the RNC searches for corresponding configuration information from the database.

• Setup of Single AMR-NB Service and Concurrence with the PS Service

Function description: This function supports the setup of a single AMR-NB service and the concurrency of AMR-NB and PS services.

• Three Service RBs Established for the AMR-NB

Function description: This function supports service transformation by means of three service RBs and reconfiguration.

• Mobility of AMR-NB

Function description: This function supports soft handover, hard handover, and relocation of AMR-NB service, and handover between 2G and 3G.

• Directed Retry of the AMR-NB Service During Assignment

Function description: This function supports directed retry of AMR-NB service during service assignment.

• Default Configuration ID of AMR-NB is 3, 10, and 15.

Function description: This function supports the default configuration ID of AMR-NB, that is, 3 (12.2 k), 10 (12.2/7.95/5.9/4.75k), and 15 (7.95 k). It is used for the handover between 2G and 3G. The RNC establishes bearer according to this default configuration, sets the default configuration in the HANDOVER TO UTRAN COMMAND message, and sends this message to the UE through the 2G network.

• Modification of AMR-NB



Function description: This function does not support the modification of AMR-NB service initiated by the RNC; it supports the modification of AMR-NB service initiated by the CN. At present, the main scenarios for the CN to initiate modification to the AMR-WB include the TFO or TrFO conditions satisfied after performance of handover, call forwarding, and intelligent service. The CN initiates the modification of AMR-NB.

• Dynamic Rate Adjustment for AMR-NB Service

Function description: This function supports dynamic rate adjustment for the AMR-NB service triggered by link level, resource congestion, and load control. If the rate adjustment threshold is met, the uplink rate is controlled by the RNC through the TFC Control, and the downlink rate is controlled by the RNC through the Iuup reverse rate control frame.

3.1.2 Signaling Flow of AMR Service

The setup flow of the AMR-WB and AMR-NB services is practically identical to that of common services. The following example demonstrates the setup flow of the DCH service in the synchronous mode.

6. D o w nl ink S yn ch ron is atio n

7 . Up li nk Sy nch ron is atio n

U E N o de B S ervi ng R NS

S ervin g R N C

C N

R R C RR C

1 0. D C C H : R ad io B earer Setu p C o mp lete

N B A P N BA P 4 . R ad io L in k R eco nfigu ratio n R ead y

D C H-F P

N B AP N B A P 8 . R ad io Li nk R eco n fi gu rat ion C om mit

R R C RR C

9 . D C CH : R ad io Bearer S etup

A pp ly n ew tran s po rt fo rmat se t

S elect L1 , L2 and Iu D ata T ran sp o rt Bearer p aramet ers

R AN A P R A N A P

1 1. R A B A ss ign men t R es po n se

5. A LC A P Iu b D ata Trans p ort B earer Setu p

2 . A L CA P Iu D ata T ran s po rt Bearer S etu p

N ot r equ ir ed to wa rd s PS d o m a in

R AN A P R A N A P

1 . R A B A s sig nmen t Req u est

[E s ta blis h m ent]

N B AP N B A P 3. R adio L ink R econ figu rat io n P rep are

[D C H A d d itio n ]

D C H-FP D C H -F P

D C H-F P

Figure 1 Signaling Flow of AMR Service



1 CN initiates establishment of the radio access bearer with RANAP message Radio Access Bearer Assignment Request. Parameters: Radio Access Bearer parameters, User Plane Mode, Transport Address, Iu Transport Association.

2 SRNC initiates set-up of Iu Data Transport bearer using ALCAP protocol. This request contains the AAL2 Binding Identity to bind the Iu Data Transport Bearer to the Radio Access Bearer (this step is not required towards PS domain).

3 SRNC requests its Node B to prepare establishment of DCH to carry the radio access bearer (Radio Link Reconfiguration Prepare). Parameters: Transport Format Set, Transport Format Combination Set, Power control information.

4 Node B allocates resources and notifies SRNC that the preparation is ready (Radio Link Reconfiguration Ready). Parameters: Transport layer addressing information (AAL2 address, AAL2 Binding Id) for Iub Data Transport Bearer.

5 SRNC initiates the setup of Iub Data Transport Bearer using ALCAP protocol. This request contains the AAL2 Binding Identity to bind the Iub Data Transport Bearer to DCH.

6 The Node B and SRNC establish synchronism for the Iub and Iur Data Transport Bearer by means of exchange of the appropriate DCH Frame Protocol frames Downlink Synchronization.

7 The Node B and SRNC establish synchronism for the Iub and Iur Data Transport Bearer by means of exchange of the appropriate DCH Frame Protocol frames Uplink Synchronization.

8 NBAP message Radio Link Reconfiguration Commit is sent from SRNC to Node B.

9 RRC message Radio Access Bearer Setup is sent by SRNC to UE. Parameters: Transport Format Set, Transport Format Combination Set.

10 UE sends RRC message Radio Access Bearer Setup Complete to SRNC.

11 SRNC sends RANAP message Radio Access Bearer Assignment Response to CN.

3.2 AMR-WB Voice Service

3.2.1 Implementation Mechanism of ZTE AMR-WB Functions

3.2.1.1 Set of AMR-WB Functions Implemented by ZTE

• Selection of AMR-WB Rates

Function description: The protocol 26.201 defines nine speech rates and one mute rate for AMR-WB, which supports the maximum speech rate of 23.85k. The database, with the AMR-WB service added, needs to save all AMR-WB rate configuration combinations. According to the maximum AMR-WB rate in the



message assigned by the CN, the RNC searches for corresponding configuration information from the database.

Note: The AMR-WB supports the voice bandwidth 50Hz-7kHz (the AMR-NB supports the voice bandwidth 200Hz-3.4kHz); therefore, it has better voice quality than the AMR-NB. Among the rates (23.85 kbps, 23.05 kbps, 19.85 kbps, 18.25 kbps, 15.85 kbps, 14.25 kbps, 12.65 kbps, 8.85 kbps, and 6.6 kbps) supported by the AMR-WB, 12.65kbps is the minimum rate that can achieve high-quality sound effects. The MOS values of 6.6 kbps, 8.85 kbps, and 12.65 kbps apparently increase as the rate rises. The MOS values of 12.65kbps, 14.25kbps, 15.85kbps, 18.25kbps, and 19.85kbps do not apparently increase as the rate rises. So the rates of 12.65 kbps, 8.85 kbps, and 6.6 kbps are recommended by 3GPP.

• Setup of Single AMR-WB Service and Concurrency with PS Service

Function description: The setup of a single AMR-WB service and the concurrency of the AMR-WB and PS services are supported in the same way as the AMR-NB.

• Three Service RBs Established for AMR-WB

Function description: Originally, the AMR-WB had only two service RBs while the AMR-NB had three. For easy conversion between these two services through reconfiguration, the 3GPP 25.331 and 34.108 specifications related to the AMR-WB recommend configuration of three service RBs. The service sub-flow associated with the third RB does not exist in the Iu port, and its actual data volume is 0 (0 × 60). The RNC requires special processing, that is, the Iu port still supports two service sub-flows, while the Iuup port needs to support the interconnection between two service sub-flows and three service RBs.

• Mobility of AMR-WB

Function description: Like the AMR-NB control policy, this function supports soft handover, hard handover, relocation, and 2G-3G handover for the AMR-WB service. This function uses the present parameters without new handover parameter added.

Note: The default inter-system handover configuration of AMR-WB is perfected in the 3GPP version released in September 2007; therefore, ZTE version 300 equipment does not support 2G-3G inter-system handover of AMR-WB, but supports 3G-2G inter-system handover.

• Directed Retry of AMR-WB Service During Assignment

Function description: Like the AMR-NB control policy, this function supports directed retry of the AMR-WB service during service assignment. This function uses the present parameters without new load balancing parameter added.

• Modification of AMR-WB

The RNC is not supported to initiate modification to the AMR-WB service, while the CN is supported to initiate the modification to the AMR-WB, which is performed in a way similar to that of the AMR-NB. At present, the main scenarios for the CN to initiate modification to the AMR-WB include the TFO or TrFO conditions satisfied after performance of handover, call forwarding, and intelligent service.



• Dynamic Rate Adjustment for AMR-WB Service

Function description: Like the AMR-NB control policy, this function supports the dynamic rate adjustment for the AMR-WB service triggered by link level, resource congestion, and load control. This function uses the present parameters without new load control parameter added. If the rate adjustment threshold is met, the uplink rate is controlled by the RNC through the TFC Control, and the CN downlink rate is controlled by the RNC through the Iuup reverse rate control frame.

3.3 Dynamic AMR Adaptation

3.3.1 Classification of Dynamic AMR Adaptation

According to the types of AMR, dynamic AMR adaptation is classified into AMR-NB dynamic rate adjustment and AMR-WB dynamic rate adjustment. The AMR-WB has rate adjustment principles and steps similar to those of the AMR-NB, except for some thresholds to trigger adjustment. The AMR-NB and AMR-WB dynamic rate adjustment based on single-link transmission power is controlled by the configuration parameter AmrRncAdjust.

There are three types of AMR dynamic rate adjustment depending on the trigger mechanisms:

• AMR dynamic rate adjustment based on single-link transmission power

Due to inner-loop power control, uplink/downlink single-link transmission power varies with the radio environment between the transmitting antennas of UE and NodeB. When the radio environment degrades, the RNC should reduce the AMR to decrease single-link transmission power to some degree. This serves to avoid heavy uplink/downlink load of a cell resulting from increase in single-link transmission power of AMR. When the single-link transmission power of AMR is low and the system load is light, the RNC may increase the AMR to provide users with better voice quality by making full use of system resources.

• AMR rate adjustment triggered by the uplink/downlink overload of a cell

When a cell has uplink/downlink overload, the rate of uplink/downlink AMR service should be reduced to decrease single-link transmission power, so as to lighten the uplink/downlink load of the cell.

• AMR rate adjustment triggered by the uplink/downlink resource congestion of a cell

Reduce the rate of uplink/downlink AMR service to lighten the uplink/downlink resource congestion.

In terms of the currently implemented functions and AMR service running, ZTE considers it unnecessary to control an uplink rate with the granularity as accurate as TTI. Therefore, ZTE has not yet implemented SRB5-based uplink AMR-WB rate adjustment.



3.3.2 Dynamic AMR Adaptation Based on Single-Link Transmission Power

AMR-WB dynamic rate adjustment and AMR-NB dynamic rate adjustment both involve uplink direction and downlink direction. They have the same principle and use the same threshold. In view of this, they are unified as AMR dynamic rate adjustment and described here.

3.3.2.1 Uplink Direction (Based on the UE Transmission power)

Uplink AMR dynamic rate adjustment is based on the transmission power reported by UE. Its operating principles are as follows:

• When the uplink transmission power reported by UE exceeds the threshold AMR_6A1 (invariably configured as 85% of the maximum transmission power (MaxUlDpchPwr) of uplink DPCH), the AMR should be reduced by one level if the current uplink AMR is not the minimum rate. If UE does not report any measurement result or the reported uplink transmission power exceeds the threshold AMR_6B1 (invariably configured as 70% of the maximum uplink transmission power of UE) some time (Trigger Timer is invariably configured as one second) after AMR reduction, we can concluded that the current transmission power is still relatively high. In this case, the AMR should be further reduced level by level until the uplink AMR is reduced to the minimum rate or the uplink transmission power reported by UE is lower than the threshold AMR_6B1. If the uplink transmission power reported by UE is lower than the threshold AMR_6B1, the AMR reduction will be terminated.

• When the uplink transmission power reported by UE is lower than the threshold AMR_6B2 (invariably configured as 35% of the maximum transmission power MaxUlDpchPwr of uplink DPCH), the AMR should be increased by one level if the current uplink AMR is not the maximum rate and the uplink load of the system is neither overloaded nor congested. If UE does not report any measurement result or the reported uplink transmission power is lower than the threshold AMR_6A2 (Trigger Timer is invariably configured as 50% of the maximum uplink transmission power of UE) some time (invariably configured as one second) after AMR increase, we can concluded that the current transmission power is still relatively low. If the current uplink AMR is not the maximum rate and the uplink load of the system is neither overloaded nor congested, the AMR should be further increased level by level until the uplink AMR is increased to the maximum rate or the uplink transmission power reported by UE exceeds the threshold AMR_6A2. If uplink overload or resource congestion occurs during the increase of the AMR, it is necessary to stop increasing the AMR. If the uplink transmission power reported by UE exceeds the threshold AMR_6A2, the AMR increase will be terminated.



Figure 2 UE Transmission Power Measurement Event Report

In the TrFO connection mode, the following judgments must be added on the basis of the steps above:

• If the target value of the AMR uplink rate increase originated from the local end is smaller than or equal to the maximum uplink rate of the Iu port, it is allowed to originate the rate increase, which then will be admitted by the admission control module. If the target value of the rate increase originated from the local end is greater than the maximum uplink rate of the Iu port, it is rejected to originate the rate increase.

When the RNC receives the rate control command from the CN, the maximum rate is the uplink target rate required by the CN. The admission control module determines the maximum uplink rate allowed by the current local end according to the uplink load state of the current cell and the single-link UE transmission power measurement report, and then returns this rate in the rate control response command to the peer end. At the same time, the RNC sends to the UE the TFC control command, requiring adjustment of the UE uplink rate to a smaller one of the maximum uplink AMR available with the local end and the maximum uplink AMR stated in the rate control command sent to the RNC from the CN.

3.3.2.2 Downlink Direction (Based on DTCP)

The downlink AMR adjustment is based on the special downlink transmission power measurement report from Node B on the basic principles as follows:

• When the special downlink transmission power reported by NodeB exceeds the threshold AMR_E1 (invariably configured as 60% of the maximum downlink transmission power (MaxDlDpchPwr) of AMR service), the downlink AMR should be reduced by one level if the current downlink AMR is not the minimum rate. If the special downlink transmission power reported periodically (Hysteresis Time is invariably configured as four seconds) by NodeB after the downlink AMR reduction still exceeds the threshold AMR_E1, we can concluded that the current transmission power is still relatively high. And the downlink AMR should be further reduced to the minimum rate, or the special downlink transmission power reported by NodeB is reduced to a value lower than AMR_E2 (invariably configured as 50% of the maximum transmission power (MaxDlDpchPwr) of downlink DPCH of AMR-WB service). If the special downlink transmission power reported by NodeB is



reduced to a value lower than the threshold AMR_E2, the AMR reduction should be stopped.

• When the special downlink transmission power reported by NodeB is lower than the threshold AMR_F1 (invariably configured as 40% of the maximum transmission power (MaxDlDpchPwr) of downlink DPCH of AMR service), the downlink AMR should be increased by one level if the current downlink AMR is not the maximum rate and the downlink load of the system is neither overloaded nor congested. If the special downlink transmission power reported periodically (Hysteresis Time is invariably configured as four seconds) by NodeB after the rate increase is still ultra-lower than the threshold AMR_F1, we can concluded that the current transmission power is still relatively low. If the current downlink AMR is not the maximum rate and the downlink load of the system is neither overloaded nor congested, the downlink AMR should be further increased level by level until the downlink AMR rises to its maximum or the special downlink transmission power reported by NodeB is higher than the threshold AMR_F2 (invariably configured as 50% of the maximum downlink transmission power (MaxDlDpchPwr) of AMR service). If downlink overload or resource congestion occurs during increase of the AMR rate, it is necessary to stop increasing the AMR rate. If the special downlink transmission power reported by NodeB has exceeded the threshold AMR_F2, the downlink AMR increase should be stopped.

Figure 3 NodeB DTCP Measurement Event Report

In the TrFO connection mode, the downlink rate depends on the downlink rate of the Iu port; In a Mobile to Mobile call, the downlink rate depends on the uplink rate of the peer end. Therefore, the downlink AMR-WB rate adjustment algorithm has the following changes in comparison with the TrFO connection mode:

• When the local end needs to adjust the downlink AMR, the RNC sends the adjusted target rate through the rate control command to the CN, which then sends this rate through the rate control command to the peer-end RNC. The returned rate control response command contains the maximum uplink rate available with the peer end. The peer end UE sends data at the smaller rate between the maximum uplink rate supported by the peer end and the target rate required by the local end, so as to complete downlink rate adjustment for the local end.



• When the uplink rate of the peer end is decreased, the downlink rate of the local end will be decreased accordingly.

When the uplink rate of the peer end is increased, the downlink rate of the local end will be increased accordingly, resulting in change of the cell downlink load and the single-link downlink D-TCP. The RNC should determine whether to decrease the increasing downlink rate according to the cell downlink load and the single-link downlink D-TCP measurement report. If the downlink rate should be decreased, the RNC sends to the CN the rate control command that contains the maximum rate supported by the local end, so as to control the downlink rate of the Iu port.

3.3.3 Dynamic Adjustment Triggered by Resource Congestion

In case of uplink/downlink resource congestion, the RNC should decrease the rate of some AMR services by priority. When the uplink/downlink resource congestion is cleared, the RNC should increase step by step the rate of any decreased AMR service that meets the rate increase conditions described above. For details, please refer to ZTE UMTS Congestion Control Feature Description.

3.3.4 Dynamic Adjustment Triggered by Load

In case of uplink/downlink overload on a cell, the RNC should decrease the rate of some AMR services by priority. When the uplink/downlink overload is cleared, the RNC should increase step by step the rate of any decreased AMR service that meets the rate increase conditions described above. For details, please refer to ZTE UTMS Overload Control Feature Description.

3.4 TrFO Support At the R99 stage, voice at the CN CS employs 64kbit/s PCM encoding based on TDM bearer. Therefore, the R99 MSC must have the voice TC function. But voice encoding/decoding is apt to reduce voice quality. The calls between mobile users, in particular, need dual voice encoding/decoding. If a codec is not used, voice quality will be improved with network bandwidth saved.

At the R4 stage, voice encoding/decoding times can be reduced by establishing a TrFO connection. The TrFO connection can be established throughout end-to-end process or between some node of a call connection. For example, for a call between UMTS UE and a fixed telephone, the TrFO connection only exists between UMTS UE and a core network. The core network and RNC in the TrFO connection must support the IuUP V2. Otherwise, no TrFO connection can be established. ZTE supports the IuUP V1 and IuUP V2. The RNC will make a choice according to CN RAB assignment parameters.

The TrFO is implemented by employing the outband signaling encoding/decoding control function (OoBTC). It is applicable to the calls between mobile networks and those between a mobile network and an external network. When the same voice encoding/decoding type is used between both call parties or between one call party and a node in the call connection, the TrFO can transparently transmit compressed voice, which improves voice quality and saves transmission bandwidth.



The node on both sides with a TrFO connection successfully established between them will use completely the same common compressed voice encoding type negotiated at the OoBTC stage. A codec must be inserted between a TrFO connection and a non-TrFO connection to convert one encoding type into another. The implementation strategy of the core network will, to the greatest extent, ensure that the insertion position can meet the following requirements:

• The insertion position should reduce the use of a transcoder and improve voice quality;

• The insertion position should save transmission bandwidth, that is, it should prolong the connection which uses compressed voice encoding data for transmission.

For a UTRAN, its IuUP initialization, reverse initialization, IuUP rate control, and IuUP reverse rate control are related to the TrFO process.

3.4.1 OoBTC Outband Codec Control

When a call is initiated, both call parties will negotiate about the codec so as to attempt to establish a TrFO operation. In an IAM, the O-MSC carries the supported codec type list and sends it to a transmission network. From the list, the transmission network deletes the types that are not supported and sends it to a T-MSC. From the list, the T-MSC also deletes the encoding types that are not supported. Then, the T-MSC selects an optimal common encoding/decoding type, returns it to the transmission network and the O-MSC, and notifies them of the currently selected encoding/decoding type. Meantime, the T-MSC feeds back the encoding/decoding type that the Terminating UE supports to the O-MSC, and begins to establish bearer on the basis of this codec. This flow is shown in Figure 4.

Codec List (v, w, x, y, z)

Codec List (v, w, x, z)

O-MSC Transit T-MSC

O-MGW T-MGWTransitMGW

Selected Codec = v, Available List (v, x, z, )

Selected Codec = v

Selected Codec = v

Selected Codec = v, AvailableList (v, x, z, )

Selected Codec = v

Bearer Established Bearer Established



Figure 4 Flow of OoBTC Outband Codec Control

The encoding type that the UE supports is transparently transmitted to the RNC by means of Uplink Direct Transfer-> NAS Message-> Bearer Capacity. Then, the RNC transparently transmits the encoding type to the MSC Server by means of Direct Transfer -> NAS Indicator ->Bearer Capacity. During RAB assignment, the encoding/decoding type lists of the calling and called parties are completely the same.

3.4.2 IuUP Initialization

IuUP initialization serves to define the mapping relationship (used at the data transmission stage) between the RNC and CN on both sides of IuUP, including RAB sub-flow combination, RFCIs, and SDU size of related RAB sub-flow.

If a bearer is successfully established, the CN will deliver an RAB assignment request message to the RNC. The RNC in R4 version must support all the SDU sub-flow combinations in the RAB assignment request message. That is, the content in the initialization frame is a universal set of sub-flow combinations determined by RAB assignment. Thus, the initialization frame will only be used to negotiate about IuUP version information and RFCI correspondence (each RFCI corresponds to a sub-flow combination). In the R99 version, this initialization process can only be initiated when the RNC receives RAB assignment/modification or RNC relocation. In the R4 version, the CN can also start this initialization process, called IuUP reverse initialization. IuUP initialization is shown in Figure 5.

*

Transfer Of User Data

CN/RNC

INITIALISATION ((RFCI, SDU sizes[, IPTIs

2)])m)

INITIALISATION ACK

* can be repeated N INIT times2) optional

RNC/CN

Figure 5 IuUP Initialization

In the RFCI set determined during IuUP initialization, the rate which corresponds to the first RAB sub-flow combination is the maximum rate in the initialization answer direction permitted by the local end when data transmission begins. The maximum rate must be greater than the guaranteed rate and SID rate. It can be modified during IuUP rate control after IuUP initialization. The rate greater than the guaranteed rate is called a controllable rate. The rate lower than the guaranteed rate cannot be modified.

3.4.3 IuUP Rate Control

IuUP rate control serves to notify the peer IuUP protocol layer of the maximum rate at the Iu port in the reverse direction of the rate control frame. In the R4 version, IuUP rate



control can be initiated by the RNC or the CN. In the R99 version, IuUP rate control can only be initiated by the RNC.

As long as an IuUP entity is not suspended by other control flows, it can initiate rate control. The controlled rates are all included in the RFC set determined during IuUP initialization. These rates that correspond to the RFC should be higher than the guaranteed rate. "Rate control" cannot be implemented in terms of the SID rate and the RFC lower than the guaranteed rate because they themselves cannot be prohibited.

CN/RNC

RNC/CN

RATE CONTROL (RFCI indicators)

RATE CONTROL ACK (RFCI indicators)

Figure 6 Flow of IuUP Rate Control

Note: The rate control frame describes the use limit of an "RFC set", which is called "RFC limit set" in the following parts.

In downlink direction, the RNC triggers the rate control frame, records the "RFC limit set" (downlink direction), and monitors the implementation behavior of the CN. If the CN still sends the data frame of the limited RFCI, the rate control frame must be resent. In uplink direction, the IuUP module of the RNC receives the rate control frame and implements the limit by means of TFC control.

The rate control initiated by the CN is as follows: After receiving a rate control message from the RNC, the CN initiates rate control to the other party of a call to limit or open the other party's uplink AMR level. Or the CN initiates a rate adjustment flow on its own according to TrFO. For example, in SRNS relocation, the CN first performs reverse initialization after a new RNC sends relocation detection to the CN. Then, the new RNC initiates a process called immediate initialization. This serves to negotiate about the maximum rate for data transmission between two IuUP entities which support TrFO.

The rate control initiated by the RNC is as follows: During dynamic AMR process, the RNC adjusts the downlink AMR level according the downlink load of a cell or the dedicated TCP measurement of an RL, and initiates rate control.

Compared with the encoding/decoding type negotiation before initialization, the IuUP rate control is in-band rate control.



4 Parameters and Configuration

4.1 Parameter List of AMR Dynamic Rate Adjustment

Table 3 Parameter List

Abbreviated name Parameter name AmrRncAdjust AMR Rate Adjustment Switch for RNC MaxUlDpchPwr Maximum Allowed Uplink DPCH Transmission Power MaxDlDpchPwr DPCH Maximum DL Power

4.2 Configuration of AMR Dynamic Rate Adjustment Parameters

4.2.1.1 AMR Rate Adjustment Switch for RNC

• Parameter Description

AMR Rate Adjustment Switch for RNC Parameter name AMR Rate Adjustment Switch for RNC

Abbreviated name AmrRncAdjust

Description This parameter indicates whether AMR rate adjustment is on or closed in the RNC.

Range and Step 0: Closed 1: Open

Unit None Default Value (note) 0: Closed

• OMC Path

View -> Configuration Management -> RNC NE -> RNC Radio Resource Management -> Advanced Parameter Manage dialog box -> RNC Radio Resource Management label -> AMR Rate Adjustment Switch for RNC

• Parameter Configuration

When the value of this parameter is "Closed", AMR dynamic rate adjustment will not be triggered due to UE internal measurement and NodeB special measurement; when the value of this parameter is "Open", AMR dynamic rate adjustment will be triggered due to the above-mentioned measurement. When this parameter is closed, AMR voice quality remains unchanged in any case; when this parameter is opened, AMR voice quality may slightly degrade according to different scenarios, but system capacity can be increased accordingly.



4.2.1.2 Maximum Allowed Uplink DPCH Transmission Power(dBm)


Maximum Allowed Uplink DPCH Transmission Power(dBm) Parameter name Maximum Allowed Uplink DPCH Transmission Power(dBm) Abbreviated name MaxUlDpchPwr

Description

This parameter indicates the maximum allowed UL power used to limit the maximum transmission power of the UE. When performing the uplink inner loop power control, the newly calculated transmission power of UE may be over the Maximum allowed UL TX power, in such case the UE can only transmit with Maximum allowed UL TX power.

Range and Step [-50, 33] dBm step 1 dBm

Unit dBm Default Value (note) 33.0dBm

• OMC Path

Configuration Management -> Rnc Radio Resource Management->Modify Advanced Parameter -> Power Control Related to Service and Diversity Mode


Background configuration value. The greater this value is, the higher the maximum permissible uplink transmission power.

4.2.1.3 Maximum Downlink DPCH Transmission Power


Maximum downlink DPCH transmission power Parameter name Maximum downlink DPCH transmission power

Abbreviated name MaxDlDpchPwr

Description

This parameter indicates the maximum downlink DPCH transmission power. When performing the downlink inner loop power control, the new transmission power must be smaller than or equal to the configured DPCH Maximum DL Power. If the newly computed transmission power is larger than the configured DPCH Maximum DL Power, make it equal to the configured DPCH Maximum DL Power.

Range and Step [-35, 15] dB step 0.1 dB Unit dB Default Value (note) See Table 4 .



Table 4 DPCH Maximum DL Power Default Value

Conversational DL 3.4k Signaling (AM): 0 dB Conversational DL WAMR6.60k~23.85k: 0dB Conversational DL 64K (PS Conversational Video): 3dB Conversational DL NAMR4.75k~12.2k: 0dB Streaming PS64k: 1dB Streaming PS384k: 4dB Streaming PS128k: 2dB Interactive PS64k: 1dB Interactive PS384k: 4dB Interactive PS128k: 2dB Background PS64k: 1dB Background PS384k: 4dB Background PS128k: 2dB Streaming CS64k: 3dB Interactive DL PS 1.2Mbps: 4dB Interactive DL PS 3.65Mbps: 4dB Interactive DL PS 7.2Mbps: 4dB Interactive DL PS 10.1Mbps: 4dB Interactive DL PS 14.0Mbps: 4dB Background DL PS 1.2Mbps: 4dB Background DL PS 3.65Mbps: 4dB Background DL PS 7.2Mbps: 4dB Background DL PS 10.1Mbps: 4dB Background DL PS 14.0Mbps: 4dB Streaming DL PS 1.2Mbps: 4dB Streaming DL PS 3.65Mbps: 4dB Streaming DL PS 7.2Mbps: 4dB Streaming DL PS 10.1Mbps: 4dB Streaming DL PS 14.0Mbps: 4dB

• OMC Path

Configuration Management ->Rnc Radio Resource Management->Modify Advanced Parameter ->Power Control Related to Service and Diversity Mode


It represents the maximum permissible downlink DPCH transmission power. It is related to service sub-class.



5 Counter and Alarm

5.1 Counter List No related counter list.

5.2 Alarm List No related alarm list.

6 Glossary A

AMR Adaptive Multi-Rate

AMRC Adaptive Multi-Rate Control

AMR-NB Adaptive Multi-Rate Narrow-Band

AMR-WB Adaptive Multi-Rate Wide-Band

C

CN Core Network

D

D-TCP Dedicated Transmitting Carrier Power

I

IAM Initial Address Message

IuUP Iu User Plane

M

MSC Mobile Switch Center

N

NAS Non-Access-Stratum

O

OoBTC Out-of-Band Transcoder Control

P



PCM Pulse Code Modulation

PSTN Public Switched Telephone Network

Q

QoS Quality of Service

O-MSC Originating Mobile Switch Center

R

RAB Radio Access Bearer

RFC RAB sub-Flow Combination

RFCI RAB sub-Flow Combination Indicator

RL Radio Link

RX Receive

RNC Radio Network Controller

S

SCR Source Controlled Rate

SDU Service Data Unit

SID Silence Information Description

SRNC Serving RNC

T

TC Transcoder

TCP Transmitting Carrier Power

TFC Transport Format Combination

TFO Tandem Free Operation

T-MSC Terminating Mobile Switch Center

TrFO Transcoder Free Operation

TX Transmit

U

UMTS Universal Mobile Telecommunications System

zte umts amr-nb and amr-wb feature description

Documents

aal2 binding

transport

dynamic adjustment

wb feature

loop power

zte confidential

current transmission

resource congestion