Research On Admission Control In CDMA Systems And The Implementation Of NAS &USIM In WCDMA

The system capacity of the cell in CDMA system is limited. Whether a new user will be admitted and how this new user will be admitted are kernel questions of the admission control. As a mainstream standard of 3G mobile communication systems, the research and development of admission control algorithms is an important issue.Firstly, the paper introduces the system capacity in CDMA system which is the foundation of admission control. In contrast to the 1G and 2G systems, users in CDMA system share the same frequency resource, so its capacity is much larger. At the same time, there is multi-access interference in the system which makes its capacity limited. Compared to the problem of limited resources, the multi-access interference is more complicated.Secondly, this paper studies admission control algorithms based on received power. According to this kind of algorithm, if the new user causes excessive interference to other users, he will not be admitted. The paper gives two methods to estimate the increment of interference, and compares their performance. Subsequently, simulation results are provided according to multi-traffic mode of WCDMA.Traffic priority and handoff priority are considered. The paper also gives the infection of different admission thresholds, and analyses adaptive problem.Then we investigate admission control algorithm based on throughput. This kind of algorithm decides whether admit a new user or not by computing the load factor of the system and the load factor of a new user. When there are two kinds of services comprised of real time service and non-real time service in the system, we give the simulation results. In the simulation, some questions are considered, such as priority between different traffic,priority between new users and handoff users.Lastly, the paper introduces some results of the research and design of WCDMA mobile phone signaling software in National Mobile Communications Research Lab. Two main modules are included: non-access stratum (NAS) in network side and universal subscriber identity module (USIM) in UE side.