Hsdpa, Call Admission Control Mechanisms

As one of the strategies of Radio Resource Management (RRM), Call Admission Control (CAC) plays an important part in 3G-telecommunication system (WCDMA etc.). Proper CAC schemes can take effective and efficient use of system resource, guarantee the Quality of Service (QoS) for user services, while ensuring the stability of system.High Speed Downlink Packet Access (HSDPA) is an evolution version of WCDMA. The Techniques employed include Adaptive Modulation and Coding (AMC), Hybrid Automatic Repeat reQuest (H-ARQ), Fast Cell Selection (FCS) and so on. New Logical channels such as High Speed Downlink Shared Channel (HS-DSCH) and High Speed Shared Control Channel (HS-SCCH) are introduced, so are several corresponding physical channels. The protocol architecture is also updated.Accordingly, traditional CAC algorithms that are employed in WCDMA are no longer suitable for HSDPA. Considering the characteristic of HSDPA, this article proposes a CAC scheme carried on HSDPA HS-DSCH, which uses both a channel load threshold and a power threshold to decide whether a call request is admitted by system or not. Simulation results indicate that this scheme is effective in decreasing call-blocking probability while maintaining system throughput rate.The remainder of this paper is organized as follows:Chapter 1 explains RRM and HSDPA conceptions briefly, introduces the structure of this article in the end. Traditional CAC schemes of WCDMA are presented in Chapter 2. Chapter 3 depicts HSDPA in detail, and proposes a CAC method for HSDPA subsequently. Chapter 4 describes the system simulation platform, which includes three layer architectures, message processing procedures and so on. Simulation results are evaluated finally. The research work is summarized in Chapter 5 and further targets are discussed.