面向Best Effort业务的IEEE 802.16m休眠模式及性能评估

Sleep Mode of IEEE 802.16m and Its Performance Evaluation with Best Effort Traffic

针对IEEE 802.16m提出的新的休眠模式,为了定量刻画系统参数对系统性能的影响、优化设计系统参数,将有数据传输的扩展监听窗口抽象为忙期,无数据传输的监听窗口及之后的休眠窗口抽象为休假期,建立一个多重休假排队模型.结合Best Effort业务,考虑忙期长度与休假期长度之间的相互依赖关系,令首个休假长度随机变化,之后的休假长度按照指数方式增长.利用嵌入马尔科夫链方法,导出排队系统的稳态解,给出能量节省率及响应时间等性能指标的表达式.结合数值实验与仿真实验,揭示不同性能指标之间的折衷关系.构造成本函数,对休眠周期等系统参数进行优化设置,为IEEE 802.16m休眠模式的算法改进提供理论依据.

Based on the novel sleep mode provided in IEEE 802.16m, aiming at mathematically analyze the influence of system parameters on system performance and optimize the system parameters, regarding the listening window with packet transmission as a busy period, the listening window without packet transmission together with the subsequent sleep window is seen as a vacation period, a queuing model with multiple-vacation is built. Concerning the Best Effort traffic, taking into account the time lengths of the vacation period and the busy period are not independent of each other, the first vacation is supposed to be a stochastic variable, the subsequent vacations are assumed to increase binary-exponentially. Applying the method of embedded Markov chain, the queuing system is analyzed in steady-state, the formulas of energy saving ratio and the response time of packets are given accordingly. Using numerical results with analysis and simulation, the trade-off between different performance measures is investigated. The system parameter of sleep cycle is optimized by constructing a cost function. The achievements in this paper have potential applications in the strategy improvement of the sleep mode in IEEE 802.16m.