基于禁忌搜索和Q-learning的CR-NOMA系统的功率分配算法

Power allocation algorithm for CR-NOMA system based on tabu search and Q-learning

针对下一代移动通信对于高速率和大规模连接的需求,对认知无线电(CR)-非正交多址接入(NOMA)混(PATSQ)算法。首先,认知基站在系统环境中观测并学习用户的功率分配,次用户采用NOMA方式接入授权信道。其次,将功率优化分配问题中的功率分配、信道状态和总传输速率分别表述为马尔可夫决策过程中的动作、状态和奖励,通过结合禁忌搜索和Q-learning的方法来解决该马尔可夫决策过程问题并得到一个最优的禁忌Q表。最后,在主次用户服务质量(QoS)和最大发射功率的约束下,认知基站通过查找禁忌Q表得到最优的功率分配因子,实现系统中次用户总传输速率的最大化。仿真结果表明,在总功率相同条件下,所提算法在次用户总传输速率和系统容纳用户数量上要优于认知移动无线网络(CMRN)算法、次用户预解码(SFDM)算法以及传统等功率分配算法。

For the demand of high speed and massive connections of next-generation mobile communication,improving the total secondary users’transmission rate by the optimization of power allocation in Cognitive Radio-Non-Orthogonal MultiAccess(CR-NOMA)hybrid system was studied,and an algorithm of Power Allocation based on Tabu Search and Q-learning(PATSQ)was proposed.Firstly,the users’power allocation was observed and learnt by the cognitive base station in the system environment,and the secondary users used NOMA to access the authorized channel.Then,the power allocation,channel state and total transmission rate in the power allocation problem were expressed as action,state and reward in the Markov decision process,which was solved by combining tabu search and Q-learning and an optimal tabu Q-table was obtained.Finally,under the constraints of primary and secondary users’Quality of Service(QoS)and maximum transmitting power,optimal power allocation factors were obtained by the cognitive base station by looking up the tabu Qtable,so as to maximize the total transmission rate of secondary users in the system.Simulation results show that under the same total power,the proposed algorithm is superior to Cognitive Mobile Radio Network(CMRN)algorithm,Secondary user First Decode Mode(SFDM)algorithm and the traditional equal power allocation algorithm in terms of the total transmission rate of secondary users and the number of users contained in the system.