授权雷达和非授权TD-LTE系统频谱共享下行功率分配算法

A Power Allocation Algorithm for OFDM-based Downlink System in Cognitive Network

针对在2.4～2.5 GHz频段上工作的授权雷达系统和非授权TD-LTE(TD-SCDMA long term evolution)系统的频谱共享问题,提出一种具体、有效的下行功率分配方法。建立了一个混合频谱共享系统模型,授权雷达系统和非授权TD-LTE系统以overlay和underlay的混合方式共存,并引入参数子载波空闲(忙碌)概率以简化模型。文中基于最优化理论,针对该问题建立相应的非凸优化模型。本模型的求解以注水算法为基础,借助蒙特卡洛法求解系统的遍历容量。最后,仿真结果证明此混合频谱共享系统模型能够很好地解决当前场景下的下行链路功率分配问题,并且验证了子载波空闲(忙碌)概率比信道增益对功率分配方案的影响更大。

A specific and effective downlink power allocation algorithm was proposed to solve the spectrum sharing problem for the OFDM downlink system.The cognitive network in this paper referred to authorized radar system and unauthorized TD-LTE system in 2.4～2.5 GHz band.The unauthorized users in this system are categorized into overlay and underlay schemes.And the probabilities while the subcarrier is busy or idle are involved in this model.Waterfilling algorithm is used to solve this non-convex optimization problem.The Monte-Carlo method is used with sufficient number of iterations to solve the ergodic capacity of the whole system.The simulation results shows that,compared to the channel gain,the probability of the subcarrier being idle has a greater effect on the power allocation method.And this mixed spectrum sharing system model is a good solution for the downlink power allocation problems.