1. Performance optimisation of UMTS radio network towards Quality of Service
Author: Mikko Rönö
Istructor: M.Sc. Jussi Setälä
Supervisor: Prof. Jörg Ott

2. Outline of this presentation
Objectives of the thesis
Background
Research methods
Key findings
Conclusion
Questions
Mikko Rönö

3. Objectives of the thesis
The objective of this thesis was to study the means of a mobile network operator to differentiate users or services according to their requirements or prioritization.
The aim was to study what became possible, in terms of QoS, with the introduction of HSPA, and which of the new possibilities are actually worth the investment.
Mikko Rönö

4. Background
The introduction of HSDPA into commercial networks showed a sharp increase in mobile data traffic. The long waited ”hockey stick” shape finally seemed to realize.
The faster data rates enabled new services with different requirements for the network.
The data traffic growth rate seemed to be faster than capacity increasing usually is.
More adaptable ways to handle the increased load and differentiated requirements could be the solution.
Although QoS has failed in mobile networks so far, the introduction of HSPA has brought fundamental changes to the picture.
Mikko Rönö

5. Research methods 1 Theory:
3GPP QoS architecture was studied to find out what is specified on QoS. Basically the specifications give an overview of the architecture, and tools to differentiate and define a level of service.
Mikko Rönö

6. Research methods 2 (3GPP QoS architecture)
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7. Research methods 3 (Services)
The variety of services offered in mobile networks was studied to find out the common requirements they set for a network.
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8. Research methods 4
The specifications of 3GPP and the feature documents of vendors were studied to learn the technologies that are actually enabling better Quality of Service in a UMTS radio network.
The focus in the technology study was in HSPA, since the older WCDMA features were expected to be known, and they did not provide enough flexibility for differentiation.
Mikko Rönö

9. Research methods 5 (Measurements)
Finally the features which were already available in real (network and user) equipment were measured in a test laboratory.
These measurement results were compared to the simulation results of previous work.
Since differentiation is not the only way of increasing QoS, the measurements included differentiation as well as the general HSPA improvements.
Mikko Rönö

10. Key findings 1
Since the specifications on the actual implementation of QoS architecture are quite loose, the vendors have different implementations for handling QoS. It could be argued that the specification is not met by some parts of the actual implementations at the moment.
Although there is an increasing variety of services and requirements in the network, they mostly set requirements for few basic attributes;
RTT
Data rate
SDU error ratio
Mikko Rönö

11. Key findings 2
ITU-T G.1010
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12. Key findings 3
Although there is a great variety of services available, there actually are not that many different services simultaneously on one base station. Thus the theoretical potential of radio interface differentiation is not realized nowadays.
The gain expected in the theory by differentiation was 50% in cell total throughput. With real equipment and realistic traffic mix the best achieved gain was 10%. In many cases there was a decrease in throughput.
Mikko Rönö

13. Key findings 4
The real gain in all of the attributes the services require, were achieved with features targeted to increase spectral efficiency.
Adaptive and efficient modulation and coding, shared channel architecture and fast retransmission handling resulted into higher data rates, lower RTT and higher SDU success rates.
The difference of achieved gain, when compared to differentiation, was 10 fold!
In addition, the gain of e.g. improved modulation or coding is available even for the only user in a cell.
Mikko Rönö

14. Conclusion
Service and user differentiation was found to be a good way to handle congestion and assure resources to the most critical services.
However,
It decreases spectral efficiency in most cases.
The gain is only experienced by some users or services, and only when the network is congested.
Performance of all the services and users was increased much more with features to increase spectral efficiency.
Mikko Rönö

15. Questions?
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16. …Thank you!

17.
Mikko Rönö