A Speech Processing Solution in a 3G Media Server

Miikka RautapääNokia Networks

Supervisor: Professor Raimo Kantola

04.11.2003

Abbreviations AEC Acoustic Echo Cancellation ALC Adaptive Level Control AMR Adaptive Multi-Rate (speech codec) AMR-WB Wideband AMR (speech codec) BSS Base Station System DSP Digital Signal Processor EC Echo Cancellation EFR Enhanced Full Rate (speech codec) FR Full Rate (speech codec) MIPS Million Instructions Per Second NS Noise Suppression RAN Radio Access Network TFO Tandem Free Operation TrFO Transcoder Free Operation

Agenda Problem Description Speech processing applications 3G Network MGW architecture Speech processing media server Testing Results Conclusions & Future Work

Problem DescriptionThe problem MGW provides services for different interfaces Every service has own speech processing

applications

The objective Find a solution to share speech processing

applications for all MGW terminations regardless of their interfaces

Used methodology Case: own solution for the media gateway project

IP

PSTN

ATMRAN

BSS

Control

Speech Processing Applications Speech coding Tandem coding avoidance (e.g. TFO, TrFO) Speech enhancements (e.g. EC, AEC, NS, ALC) Speech synthesis Speech recognition Conferencing, Announcements, Interactive

voice response Etc… Need lots of processing power

3G Network (1/2) Next-generation

network Media gateway (MGW)

routes traffic between packet network and circuit-switched network.

Media server processes, manages, and

delivers the media resources.

Open, scalable architecture

3G Network (2/2) 3GPP release 4 network

MGW MSC Server IP/ATM backbone

Simplified architecture of the 3GPP release 4 network

MGW Architecture Interfaces

ATM, RAN PSTN, BSS IP

DSP Unit Control

processor DSP chips

DSP softwareMGW applications provide different user plane framing protocols for different interfaces, and different supplementary services (e.g. announcements) for other MGW applications.MGW server processes provide basic functions for MGW applications.DSP Platform provides connection management, timer services and basic operating system functions.

Speech Processing Media Server Integrated part of the MGW

DSP Serves MGW applications with

different speech processing applications FR, EFR, AMR ALC

V-model design Client/server Signalling interface

* Own contribution

Testing Unit, integration and system testing True media gateway hardware Bit-exact tests Performance measurements

Codecs Overhead (control code)

Results 510 test cases (passed)

FR EFR AMR DTX

Overhead

MIPS

2.2 11.1 8.0-11.1

0.2 0.16-0.24

Control

Codecs

ALC Multi channel

60 436 8 6 Performance measurements (encoder&decoder)

Conclusions Speech processing applications

Several applications Need lots of processing power

Media server Optimised as enhanced services platform Integrated to the MGW

DSP Layered software (applications – servers – platform)

Results 510 test cases Performance depends on application algorithms

Future Work Other applications (e.g. AMR-WB, AEC)

Easy to integrate Interface

Signalling Function calls