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 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
BTS
BSC
2G BSS
MSC
Server
Mc
A
Mc
ATM or IP Nb
backbone
Iu-CS
BTS
MGW
MGW
Iub
CS CORE
RNC
Iu-PS
Iur
BTS
SGSN
Iub
RNC
3G RAN
PS CORE
PSTN
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
MGW
RAN
Iu
Termination
Nb
Termination
IP/ATM
Backbone
Nb
Termination
PSTN
Termination
DTMF
Detection
PSTN
Call Example (RNC)
Core
network
RNC
RNC
Iur
AMR MDC
DRNC MDC
Branch
Branch
Branch
Iub
Node B
Node B
Node B
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
Before
Unit 2
Unit 1
Unit 2
Unit 1
After
Unit 2
Challenges Signal Processing
Resource Allocation
= Service setup
= End of call
Call 1
Call 2
Call 3
Call 4
Call 5
time
Combined
service
sequence
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
SP service and
unit capacity
configuration
RNC/ MGW
configuration
Evaluated
algorithms
Traffic
configuration
Simulator
Data for
analysis
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!