感知/传输帧结构下基于有效容量的多功率分配策略

Multi-power Allocation Strategy Based on Effective Capacity in Sensing/Transmission Frame Structure

传统认知无线网络功率分配时,一般假定主用户(Primary User,PU)状态在一帧内不发生变化,并且未考虑传输时延的问题。在下一代移动网络中,由于主用户活跃程度的提高以及严格的时延要求,上述问题是功率资源分配时亟需考虑的重要方面。针对这种问题,以最大化认知用户可获得的有效容量为目标,采用基于感知/传输帧结构的四状态三功率传输策略,从而满足时延约束要求,且考虑了主用户的活跃程度。建立了系统以及状态转移模型,设计了使用服务质量(Quality of Service,QoS)约束的平均信道有效容量优化函数,采用Lagrangian方法详细分析推导了最佳有效容量的理论近似值,并对影响有效容量的不同因素进行了仿真分析。与传统的传输策略相比,在保证主用户正常通信的前提下,采用所提算法,认知用户的有效容量得到了显著提高。

For the existing power allocation problem in cognitive radio network,it is usually assumed that the state of the primary user(PU)is not changed within a frame.Meanwhile,transmission delay is seldom considered.However,in the next generation of mobile networks,the high PU′s activity leads to that the PUs′state may be changed even within a short frame,and the transmission delay has also a high requirement.For these questions,an optimization problem as maximizing the effective capacity of cognitive users(CUs)is formulated,and the four-state and three-power transmission strategy based on the sensing/transmission frame structure is adopted.Futuremore,the transmission delay requirement and the PU′active degree are considered.Then,the system and the state transition model are established,and the average channel effective capacity optimization function under quality of service(QoS)constraints is designed.The theoretical approximation of the optimal effective capacity is analyzed by using the Lagrangian method,where the different factors influencing the effective capacity are considered.Compared with traditional transmission strategy,the effective capacity of the CUs is significantly improved by the proposed algorithm.