Evaluation of Signal Processing Resource Management Algorithms in 3G

1. Evaluation of Signal Processing Resource Management Algorithms in 3G Markku Piiroinen S-38.310 tietoverkkotekniikan diplomityöseminaari 7.9.2004

2. General Information • Thesis is written at Nokia networks • Supervisor: Professor Jorma Virtamo • Instructor: Sami Lehesaari, M.Sc.

3. 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

4. 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

5. 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

6. 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

7. 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

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

9. Background Information

10. PSTN BSC BTS BTS BTS Network Architecture MSC Server Mc Mc A 2G BSS ATM or IPbackbone Nb Iu-CS MGW MGW Iub CS CORE RNC Iu-PS Iur SGSN Iub RNC PS CORE 3G RAN

11. 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, ...)

12. 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

13. 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

14. DSP Features • Special purpose Processors • Small memory • Powerful in data processing • Cheap • compared to general purpose processors • there are many of them - big multplier

15. MGW MGW Nb Termination PSTN Termination PSTN Iu Termination Nb Termination RAN DTMF Detection IP/ATM Backbone Call Example (MGW)

16. Node B Node B Node B RNC RNC Iur AMR MDC DRNC MDC Core network Branch Branch Branch Iub Call Example (RNC)

17. 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

18. Unit 1 Unit 2 ? Unit 1 Unit 2 Unit 1 Unit 2 Before After Challenges Signal Processing Resource Allocation

19. = Service setup = End of call Call 1 Call 2 Call 3 Call 4 Call 5 time Combined service sequence Challenges Signal Processing Resource Allocation

20. 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)

21. 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

22. Simulator Usage Traffic configuration SP service and unit capacity configuration Simulator RNC/ MGW configuration Data for analysis Evaluated algorithms

23. 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)

24. 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

25. 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

26. 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

27. Future Work • Better algorithms(?) • Information about call type • pooling • capacity pre-reservation • Reorder of services • … more than just resource management changes are needed

28. Questions? Thank You!