Optimal power allocation for MIMO-OFDM based Cognitive Radio systems with arbitrary input distributions
Optimal power allocation for MIMO-OFDM based Cognitive Radio systems with arbitrary input distributions
复制标题
具有任意输入分布的基于 MIMO-OFDM 认知无线电系统的最优功率分配
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Evans
中科院分区：
文献类型：
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作者：
Ahmed Sohail;Mohammed Al;P. Xiao;B. Evans
在认知无线电（CR）系统中，在给定对主用户（PU）造成的干扰的阈值的情况下，可以通过优化发射功率来最大化次用户（SU）的数据速率。在传统的功率优化算法中，假设高斯输入分布，这是不现实的，而有限符号字母（FSA）输入分布（即，M-QAM）更适用于实际系统。本文研究了在FSA输入下基于多输入多输出正交频分复用的CR系统的功率优化问题，利用互信息和最小均方误差之间的关系，推导出了一种最优功率分配方案。所提出的方案示出，以节省发射功率相比，其传统的同行。此外，我们提出的方案实现了更高的数据速率相比，高斯优化的功率，由于更少的子载波被置零。提出的最优功率分配算法进行评估，并与传统的功率分配算法使用Monte Carlo模拟进行比较。数值结果表明，对于SU发射机和PU接收机之间的距离范围在50米到85米之间，所提出的算法的发射功率节省在13- 90%的范围内，而速率增益在5-31%的范围内，这取决于调制方案（即，BPSK、QPSK和16-QAM）。
In Cognitive Radio (CR) systems, the data rate of the Secondary User (SU) can be maximized by optimizing the transmit power, given a threshold for the interference caused to the Primary User (PU). In conventional power optimization algorithms, the Gaussian input distribution is assumed, which is unrealistic, whereas the Finite Symbol Alphabet (FSA) input distribution, (i.e., M-QAM) is more applicable to practical systems. In this paper, we consider the power optimization problem in multiple input multiple output orthogonal frequency division multiplexing based CR systems given FSA inputs, and derive an optimal power allocation scheme by capitalizing on the relationship between mutual information and minimum mean square error. The proposed scheme is shown to save transmit power compared to its conventional counterpart. Furthermore, our proposed scheme achieves higher data rate compared to the Gaussian optimized power due to fewer number of subcarriers being nulled. The proposed optimal power algorithm is evaluated and compared with the conventional power allocation algorithms using Monte Carlo simulations. Numerical results reveal that, for distances between the SU transmitter and the PU receiver ranging between 50m to 85m, the transmit power saving with the proposed algorithm is in the range 13-90%, whereas the rate gain is in the range 5-31% depending on the modulation scheme (i.e., BPSK, QPSK and 16-QAM) used.