Hsdpa Wireless Communication System, Packet Scheduling Algorithms

With the rapid development of communication technology, mobile users are increaseing dramatically. Communication system capacity is also increasing. Besides the traditional speech service, the future mobile communicaiotn system can also provide other services, such as low/high rate data, video etc. Heterogeneous services have different quality of service (QoS) requirements,for example, the requirements of maximum packet delay, the maximum acceptable packet drop rate, the minmum data rate. There are three issues for wireless network design, one is to guarantee QoS requirements for hetergenerous services, another is to guarantee the fairness between users, the third is to maximize the utilization of the wireless resource. All of thoese will depend on the Radio Resource Management (RRM). Because the future mobile communicaiotn system is based on the data traffic, wireless scheduling is the key of influencing system performance and guaranteeing users'QoS.In order to satify the increasing demand on the high data rates, the 3GPP introduces a new feature in the Release 5 specifications denominated High Speed Downlink Packet Access (HSDPA). The target of the HSDPA concept is to increase the peak data rates, improve the quality of service, and enhance the spectral efficiency for downlink packet traffic. Some new technologies are introduced in HSDPA ,including a shorter Transimission Time Interval (TTI),Adaptive Modulation and Coding (AMC) scheme and a fast physical layer Hybrid ARQ mechanism.This dissertation focuses on the packet scheduling in HSDPA communicaiotn system.First of all, we discuss the typical packet scheduling algorithms for HSDPA system and investigates their performances by simulations. We evaluate the user throughput performance of the scheduling algorithms which have no delay-constrainted, and the real-time packet delay performance and real-time traffic throughput performance of the ones which have delay-constrainted.Chapter3 proposes a wireless packet scheduling algorithm which can support multi-services in HSDPA system. In designing this scheduling algorithm, we not only consider the QoS requirement of real-time serivce, but also consider the transmission request of non-real-time service. Through the adjustment and optimization of the parameter, the proposed algorithm can guarantee the QoS of the real-time service and maximize the system capacity at the same time.In order to demonstrate the performance of the proposed algorithm, we compare our algorithm with M-LWDF. Numerical results show that the proposed algorithm is superior to the M-LWDF algorithm.To denmostrate and evaluate the proposed algorithm in this dissertation, we use OPNET? Modeler to model HSDPA packet scheduling simulation platform. The retalted modeling work is discussed in details in Chapter4.