Evaluation of Signal Processing Resource Management Algorithms in 3G Markku Piiroinen S tietoverkkotekniikan diplomityöseminaari

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 speech 3G = 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 Nb ATM or IP backbone PSTN BSC A BTS Iub PS CORE Iu-PS Mc BTS Iur MGW RNC MSC Server 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 Iu Termination Nb Termination MGW Nb Termination PSTN Termination DTMF Detection IP/ATM Backbone PSTN RAN

Call Example (RNC) RNC Branch AMR MDC Branch DRNC MDC 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 1Unit 2Unit 1Unit 2 AfterBefore ? Unit 1Unit 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!