Rearch On Hybrid ARQ Technique And Packet Scheduling Algorithm In HSDPA System

Nowadays, many data services such as video, streaming media download that require the system to provide higher transmission rates and shorter delays with the continuous development of the third generation mobile communication technology. In order to have the better development of data services, 3GPP introduced High Speed Downlink Packet Access technology by improved on the air interface. On the one hand, HSDPA technology to meet the higher requirements of the fast-growing internet business, real-time services and multimedia applications on the network bandwidth, QoS and scalability; on the other hand, HSDPA can solve the problem of the wireless channel susceptible to interference, fading and others. Therfore, many operators pay attention to it. This paper focuses on the hybrid ARQ technique and packet scheduling algorithm in HSDPA System.The main research contents and conclusions of this paper includes the following two aspects:(1) Research on hybrid ARQ technology. The introduction of HARQ technology in HSDPA system, whether the system performance is improved or the advantage is significant, which is the focus of this paper.First, analyse the application of HARQ retransmission protocol and function implementations in the HSDPA system, and then focus on HARQ retransmission combining proposal and the impact on system performance of the introduction of HARQ technology , simulation results show that the HARQ technology plays a vital role to achieve high speed data transmission in the low signal noise ratio environment, and the Type-Ill HARQ has the greatest impact on system performance. Finally research on a hybrid ARQ technology based on the constellation rearrange, and analyse the constellation rearrange process combine with HSDPA modulation, apply the basic types of HARQ technology combined with a constellation rearrange technique in HSDPA system, simulation results show that the introduction of this technology can greately improve the system performance in low SNR conditions,and the system only has to increase a small amount of complexity. (2) Research on packet scheduling algorithm. Three classical packet scheduling algorithms RR,Max C/I and PF are analyzed and studied from the point of system throughput and user fairness ,which are supported by Non-Real time services in HSDPA system. An enhanced packet scheduling algorithm combined with hybrid automatic request retransmission is proposed to deal with the problem of long retransmission delays in PF algorithm,which HARQ is based on the constellation rearrange,and presents a suitable model for packet scheduling in HSDPA system.The proposed algorithm can increase the priority , reduce retransmission delay of a UE that has HARQ retransmission packets, and improve the utilization of resource effectively; then build the OPNET network simulation platforms, simulate HPF algorithm in fairness, system throughput and data delay by comparing method, simulation results show that the HPF algorithm can reduce retransmission delays, while still ensuring the system throughput and user fairness.