一种在无线衰落信道上支持实时业务的分组调度算法

Packet Scheduling Supporting Real-Time Data Service over Wireless Fading Channels

无线分组调度算法能为蜂窝网络中的移动用户提供服务质量的保证。在此问题上,以前的研究工作中一个经典的假设是基站与用户之间的信道条件变化为一平稳随机过程。但在实际情况中,这样的平稳假设并非总是合理的。研究表明基于平稳假设的调度算法,如流行的M-LWDF和EXP-rule算法,在非平稳信道上的性能下降明显。在CDMA蜂窝通信系统中,为在时变衰落信道上支持实时数据业务,该文提出一种基于模糊逻辑控制的分组调度算法,简称FROS。它能在保证用户QoS要求的同时,考虑到无线信道的快衰落特性而充分利用多用户分集(Multiuser diversity)所带来的增益,从而提高系统容量。系统级仿真证明,FROS算法能在优化系统分组时延性能和优化系统吞吐量性能之间保持良好的平衡和折衷,在平稳信道和非平稳信道的条件下都能获得比M-LWDF 和EXP-rule算法更好的性能。

Wireless packet scheduling algorithms, which have been proposed for Quality of Service （QoS） for mobile users in cellular networks, depend on the fundamental idea that the service rate allocated to each user is proportional to a positive weight. Previous work on this problem has typically assumed that the channel conditions between the base station and the users are governed by a stationary stochastic process. However, such stationary assumption is not always reasonable and the study shows that the algorithms based on the stationary assumption, such as a popular algorithm known as M-LWDF, would have extremely poor performance over non-stationary channels. In this paper an opportunistic scheduling model is designed by means of fuzzy logic, which can exploit the time-vary nature of channel conditions to enhance system capacity while satisfying diverse QoS requirements. Simulations illustrate that this design can achieve better performance than previous algorithms under both stationary channel conditions and non-stationary channel conditions.