一種在無線衰落信道上支持實時業(yè)務的分組調(diào)度算法
Packet Scheduling Supporting Real-Time Data Service over Wireless Fading Channels
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摘要: 無線分組調(diào)度算法能為蜂窩網(wǎng)絡中的移動用戶提供服務質(zhì)量的保證。在此問題上，以前的研究工作中一個經(jīng)典的假設是基站與用戶之間的信道條件變化為一平穩(wěn)隨機過程。但在實際情況中，這樣的平穩(wěn)假設并非總是合理的。研究表明基于平穩(wěn)假設的調(diào)度算法，如流行的M-LWDF和EXP-rule算法，在非平穩(wěn)信道上的性能下降明顯。在CDMA蜂窩通信系統(tǒng)中，為在時變衰落信道上支持實時數(shù)據(jù)業(yè)務，該文提出一種基于模糊邏輯控制的分組調(diào)度算法，簡稱FROS。它能在保證用戶QoS要求的同時，考慮到無線信道的快衰落特性而充分利用多用戶分集(Multiuser diversity)所帶來的增益，從而提高系統(tǒng)容量。系統(tǒng)級仿真證明，F(xiàn)ROS算法能在優(yōu)化系統(tǒng)分組時延性能和優(yōu)化系統(tǒng)吞吐量性能之間保持良好的平衡和折衷，在平穩(wěn)信道和非平穩(wěn)信道的條件下都能獲得比M-LWDF和EXP-rule算法更好的性能。Abstract: 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.
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