(The) code switching & replacement schemes via an optical repeater and a secondary scrambling code for the enhancement of user capacity in WCDMA system

다국어 초록 (Multilingual Abstract)

Recently, the requirements for multimedia service have been increased in WCDMA system. This multimedia service requires much power and many code occupations. However, the total quantity of these resources, such as power and code, are not enough to support all of requirements for all users. Therefore, many researchers have been studied to accept these requirements as possible.With this background, this thesis proposes “the resources extended call admission algorithm” to accept more users. The power resource and the code resource are considered to support users. The power resource for call admission is extended by the use of repeaters. When a new requirement is rejected by power shortage, this power resource of a repeater in same sector is used for the rejected user. The code resource is extended by the use of a secondary scrambling code. This secondary scrambling code generates an additional channelization codes tree. A rejected user has an additional chance to be supported by the code extension.These extensions of the resources improve the user capacity and make more high data services accepted. However, the interference is also increased due to increase of user interference and the use of more power for data services. Therefore, the resource management is necessary for these resources to utilize more efficient.This thesis also proposes the channel switching method and code replacement method as the resource managements. The channel switching method helps users to receive through better channel during service time. For this process, the secondary common pilot channel is used as a measurement for estimating channels state.In this thesis, two types OVSF codes tree is considered due to the existence of a secondary scrambling code. The code replacement is proposed as the method to use a kind of OVSF codes tree as fully as possible. It is useful to decrease the interference by different types of codes.Simulation is performed on three sector model with a repeater in a sector. Simulation results show that the proposed methods provide the improvement of user capacity and the more data services are supported in the system.