在TDMA通信系统中,时隙分配是影响业务时延性能的重要因素,包括时隙数量分配(带宽分配)、时隙分配周期(TDMA帧长)和时隙位置分配三方面.本文针对可变速率和固定速率两类业务,基于随机服务系统理论和交通流理论建立了业务时延模型,得到了平均时延的解析式,分析了时隙数量、时隙位置和TDMA帧长度对业务时延影响的规律和特点.结果表明时隙位置分配越均匀,越能改善业务的平均时延和时延抖动性能;而在传统的时隙连续分配方式下,增加时隙数量分配对时延性能提高非常有限.在DVB-RCS卫星系统等具有较长帧设计的TDMA系统中,采用时隙均匀分配方式能够有效提高业务时延性能.计算机仿真验证了建模分析的正确性.%In TDMA communications, timeslot assignment has important influence on delay performance, which includes timeslot count (bandwidth assignment), assignment period (TDMA frame length) and timeslot location. In this paper, we firstly proposed traffic delay models based on stochastic service system theory and traffic flow theory for variable bit rate and constant bit rate traffics.Then the analytical formula for average delay was provided. Furthermore, we analyzed the characteristic of influence of timeslot count, assignment period and timeslot location on traffic delay performance, and the results showed that when the timeslot location in frame is more uniform, the average delay and jitter performance of traffic is better. With the mode of consecutive timeslot assignment only increasing bandwidth could promote the delay performance quite limitedly. In TDMA systems with long frame length, such as DVB-RCS satellite systems, the delay performance of traffics can be guaranteed effectively according to uniform timeslot assignment. The validity of proposed models was verified by computer simulation.
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