【作者】 张毅杰；

【导师】 朱光喜；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2009， 硕士

【摘要】 随着移动通信技术宽带化、多媒体化的趋势日益明显,人们对移动通信系统的要求与日俱增:不仅需要高速的数据传输速率,而且服务质量需要得到一定的保障。面对人们不断变化的需求,新的技术孕育而生。当前是移动通信技术发展的关键时期,3GPP此时推出LTE。为了纠正恶劣的无线信道带来的传输错误,LTE系统采用HARQ和ARQ两种重传技术加以控制:经过物理层HARQ技术的纠错和重传之后,如果数据仍然无法恢复,那么数据链路层将通过ARQ技术对发送失败的数据再次进行重传,从而确保数据传输的可靠性。本文以与中国移动研究院合作的“LTE无线接口协议仿真评估”项目为背景,对LTE系统两层重传方案进行了深入的调研、仿真和分析。虽然物理层和数据链路层两层都使用重传技术可以进一步提高数据传输的可靠性,但是为了降低系统开销和实现复杂度,LTE系统两层重传方案物理层采用N通道停止等待式HARQ协议,因此数据的发送只能以HARQ通道为单位,导致物理资源的使用效率不高,影响了系统吞吐率和业务时延。首先,针对LTE系统两层重传方案的不足,本文提出了基于RLC子层的跨层HARQ重传方案。然后,本文从系统框架、传输格式、资源分配算法和HARQ流程四个方面对本方案进行了详细的阐述。本方案通过跨层设计,充分利用HARQ与ARQ之间的共享信息,使得不同QoS需求的数据可以独立的进行发送,提高了物理资源的使用效率,在改善系统吞吐率和业务时延的同时,保障了多业务的QoS,从而克服了LTE系统两层重传方案的不足。最后,本文对本方案进行了严格的仿真,并且将本方案的仿真结果与LTE系统两层重传方案进行了性能对比,从吞吐率和时延两个方面验证了本方案的优势。更多还原

【Abstract】 As the broadband and multimedia trend of mobile communication technologies is becoming increasingly prominent, the demand for mobile communication systems has kept rising with each passing day: not only the data rate, but also the quality of services. New technologies were born to meet people’s constantly changing needs. At the moment of the development of mobile communication technologies, 3GPP proposed LTE which uses both HARQ and ARQ to correct the errors caused by bad transmission condition in wireless channel. If the original data cannot be recovered after correction and retransmission by HARQ in physical layer, ARQ will again retransmit the data in data-link layer to insure reliable transmission.This thesis is based on the project‘LTE Radio Access Network Protocol Simulation and Evaluation’in which CMCC and our lab are working in collaboration with each other and does some investigation, simulation and analysis work on LTE retransmission scheme. Although retransmissions on both physical layer and datalink layer will improve the reliability of transmission more, LTE adopts N-process stop-and-wait ARQ protocol as the retransmission protocol of HARQ in physical layer in order to reduce system cost and implementation complexity. Therefore data has to be sent in unit of HARQ process so that the ideal resource utilization efficiency cannot be realized. As a result, system throughput is decreased and traffic delay is increased. In order to solve this problem, this thesis firstly proposes the cross-layer HARQ retransmission scheme based on RLC sublayer. Then this thesis explains the architechture, transportation format, scheduling algorithm and HARQ workflow of this scheme in detail. This scheme combines HARQ and ARQ by cross-layer design in order to improve resource utilization efficiency. This scheme not only increases system throughput and decreases traffic delay, but also guarantees the quality of service of multiple traffic. In the end this thesis does some simulation of this scheme and contrasts the performence of this scheme with that of LTE retransmission scheme, which confirms the advantages of this scheme.更多还原