Auto-tuning of RRM parameters in UMTS networks. Feasibility study.
Tutor / director / evaluatorGarcía Lozano, Mario
Document typeMaster thesis
Rights accessOpen Access
The present PFC is located inside the framework of the UMTS networks, and more specifically in the development of new Radio Resource Management (RRM) algorithms capable to maximize the capacity and the performance of the network. In this sense a powerful simulation tool capable to analyze in depth the behavior of the UMTS network under different simulation scenarios has been developed. It has been focused in the study of the main algorithms that manage the allocation of radio resources in UMTS networks: Power Control (PC), Admission Control (AC) and Soft/Softer Handover (SHO). The problem observed in classical SHO strategies is the rigidity of the mechanism, which cannot adapt to variations in the traffic patterns. The improvements on SHO procedures are based on dynamic automated tuning of SHO parameters. A three blocks based functional architecture is described to adapt parameters to service mix dynamics and overcome capacity problems. Several tests have been done over different traffic situations in order to demonstrate the feasibility of the Auto-Tuning System (ATS). The results obtained show a considerable increment in the network capacity. In this sense ATS is considered as an effective pre-congestion-control strategy. Referring now to AC strategies, it is necessary to underline that three new AC algorithms have been implemented: Dynamic AC, Complete Partitioning AC (CP-AC) and Complete Sharing AC (CS-AC) strategies have been developed with the same goal, enhance the capacity of the network. Dynamic AC was proposed to provide flexibility to the current AC algorithm. This strategy is based on the ATS philosophy where a dynamic AC threshold is fixed to the optimum threshold in real time according to the current service mix. On the other hand, CS-AC and CP-AC are complex strategies based on static algorithms where fixed thresholds or load margins were applied in order to note their advantages and drawbacks depending on the users distribution, uniform or mostly close to the cell edge. As a result of this project a scientific publication inside the context of COST european projects has been carried out. In special, is about the COST 2100 ”Pervasive Mobile & Ambient Wireless Communications” and the title of the publication is ”Automatic Tuning of Soft Handover Parameters in UMTS Networks”. The paper was presented in the meeting number 3, held in Duisburg (Germany) between 10th and 12th of September 2007.
Due to the intrinsic characteristics of WCDMA and the great number of services offered by UMTS, its radio channel is much more dynamic compared with GERAN systems. The traffic fluctuations and users mobility can cause the impairment of the network performance and of the quality of service (QoS) in certain cells. In the worst case a significant degradation of the QoS may be observed and as a result the operator defined targets are not met. Nowadays UMTS operators have fixed, and usually uniform, settings for their network parameters. This static configuration is not able to adapt automatically to the changes that occur in the network. A fixed parameter setting then gives a non optimal solution for the network optimization process and thus the utilization of the radio interface is not maximized. The goal of the automated tuning is to adjust dynamically these parameters in a continuous way without human intervention, which is only required in definition of the reference QoS. The current PFC aims at validating the feasibility of automated optimization of certain UMTS RRM parameters. The main tasks to be developed by the students are: - Simulator developement (Matlab programmed). A basic static Montecarlo simulator is available as a reference. - Study of UMTS handover algorithm and study of potential parameters to be automatically tuned. - Proposal of algorithm to tune the previously selected parameters, and evaluation of achieved gains. - Study of UMTS CAC algorithm and study of potential parameters to be automatically tuned. Development of first and basic ideas to propose tuning algorithm.