Evaluation of Signal Processing Resource Management

Algorithms in 3G

Markku Piiroinen

S-38.310 tietoverkkotekniikan diplomityöseminaari

7.9.2004

General Information

• Thesis is written at Nokia networks

• Supervisor: Professor Jorma Virtamo

• Instructor: Sami Lehesaari, M.Sc.

Contents• Background • Objectives of the thesis• Motivation• Methodology• Background Information

– Network Architecture (RNC, MGW)– Signal Processing (SP) and DSPs– Calls and SP-services

• Signal processing resource management• Tools• Simulations• Measurements• Results

Background• Evolution from 2G to 3G networks offers a

wide variety of new features to mobile UE

• Roughly:2G = mobile speech3G = mobile internet

• 3G offers service independent technology platform => 3G resource management is not trivial

Objectives of the thesis• The goal is to improve the signal processing

resource management in network elements:– Radio Network Controller (RNC) – Media Gateway (MGW)

• Enable resource management algorithm evaluation without real environment– evaluation in PC environment

• Develop simulation SW and tools to ease algorithm development for future signal processing services

Motivation (1/2)• The use of real target system takes a lot of

resources– time, – people, – HW, all has limited acces and availability and

costs money• Total system is not always available

– or does not work well enough to run mass tests– other processes may disturb the run

Motivation (2/2)

• Simulated time != realtime– test runs of few days can be run in one to few

hours• Debugging

– identical resouce management code is used– even a samll bug can cause a long test re-run

• Data collection is easier and more data can be collected– huge monitorings affect system performance– in simulated system it is possible to track all the

needed details

Methodology

• Signal Processing (SP) resource selection algorithm evaluation by simulation– Simulator development– Algorithm implementation– Traffic generation– Data analysis

Background Information

Network Architecture

CS CORE

3G RAN

2G BSS

Iu-CS

Mc

NbATM or IPbackbone PSTN

BSC

A

BTSIub

PS CORE

Iu-PS

Mc

BTS

BTS

Iur

MGW

RNC

RNC

MSCServer

Iub

MGW

SGSN

Radio Network Controller (RNC)

Related RNC functions:• Outer Loop Power Control (OLPC)

• Macro Diversity Combining (MDC)

• Ciphering

• Many protocols related to radio channels (UP, MAC, RLC, ...)

Media Gateway (MGW)

Related MGW functions:• Speech Transcoding (AMR, G.711, ...)

• Speech enhancements (EC, noise suppression, ...)

• Automatic level control (ALC)

• Supplementary services– DTMF (generation/detection)

– Tones

– Announcements

– Conference calls

Signal Processing and DSPs

• Most of speech and other user data manipulations in 3G is done by Digital Signal Processors (DSPs)

• System contains thousands of DSPs – even small inefficiencies cause a lot of wasted capacity

DSP Features

• Special purpose Processors

• Small memory

• Powerful in data processing

• Cheap – compared to general purpose processors– there are many of them - big multplier

Call Example (MGW)

MGW

IuTermination

NbTermination

MGW

NbTermination

PSTNTermination

DTMF Detection

IP/ATM Backbone

PSTNRAN

Call Example (RNC)

RNC RNC

Branch Branch

AMR MDC

Branch

DRNC MDC

Node B Node B Node B

Iub

Iur

Core network

Challenges Signal Processing Resource Allocation

• Different calls and related services have very different resource needs.– Nbr of needed services, delay, memory, MIPS,

communication, ...

• Resource fragmentation• Limited information at the call setup• Minimize the inter-unit communication• Additional limitations in unit selection

– Availability issues, load balancing …

• Dynamic problem

Challenges Signal Processing Resource Allocation

Unit 1 Unit 2 Unit 1 Unit 2

AfterBefore

?

Unit 1 Unit 2

Challenges Signal Processing Resource Allocation

Call 2

Call 3

time

Call 4

Call 5

Combined service sequence

Call 1

= Service setup

= End of call

Signal Processing Resource Manager (SPRM)

• The task of SPRM is resource selection for signal processing services– Global centralized resource manager

• Main tasks of SPRM– Makes the resource selection (unit selection)– Set service configuration into units (DSP+other)

Tools

• Tools are needed to:– Import the real system configuration into the

simulator– Traffic generation

• The simulator body– reads the configuration data and runs the

algorithms on given traffic

Simulator Usage

Data for analysis

Evaluated algorithms

SP service and unit capacity configuration

RNC/ MGW configuration Simulator

Traffic configuration

Simulations (1/2)

• Simulations were run with one HW configuration

• With different loads – near the system limits

• Two kind of traffic profiles were used– One call type – Mixture of all types (each call type had certain

probability)

Simulations (2/2)

• The load was set so that the system runs on the limit most of the time – There are no problems with light traffic– Problems arise only when the system is almost

out of resources

Measurements

• Call/service success rate

• Resource utilization

• Realized/offered traffic

• + Many other parameters to assure the result correctness– mean call duration,– mean inter-time (between calls and services in one call),

etc

Results

• It is not easy to make the unit selection in the case when all the units are almost full

• Small calls/services are ok but it is difficult to find resources for bigger services

Future Work

• Better algorithms(?)

• Information about call type – pooling – capacity pre-reservation

• Reorder of services

• … more than just resource management changes are needed

Questions?

Thank You!