可获得发射分集的正交空频索引调制算法

A Quadrature Space-Frequency Index Modulation Algorithm for Achieving Transmission Diversity

针对正交空频索引调制(QSFIM)算法不能获得发射分集的缺陷,提出了一种用于多输入多输出-正交频分复用系统中可获得发射分集的正交空频索引调制(TDA-QSFIM)算法。该算法首先将两个调制符号通过哈达玛矩阵和旋转矩阵关联起来构造对角码,然后通过两次独立地选择空频资源块中的索引号,将对角码的同相和正交分量分别放在空频码的不同位置得到每个资源块上的发送信号码字。根据空频编码的秩准则,由于该算法在每个资源块上的码字设计使得发射分集阶数为2,因此该传输算法得到了更好的误比特率性能。仿真结果表明:在独立瑞利信道下,频谱效率为1.78 bit/(s·Hz^(-1))、误比特率为10^(-5)时,TDA-QSFIM算法比QSFIM算法具有大约3.5 dB的性能增益;在相关瑞利信道下,当误比特率为10^(-3)时,TDA-QSFIM算法比QSFIM算法有大约5 dB的性能增益。

A new quadrature space-frequency index modulation(TDA-QSFIM)scheme which can obtain transmission diversity in MIMO System is proposed to solve the shortcoming that the quadrature space-frequency index modulation(QSFIM)algorithm cannot achieve transmission diversity.Firstly,two modulated symbols are related through a Hadamard matrix and a rotation matrix to construct a diagonal code,and then the transmitted signal codeword on each resource block is obtained by independently selecting the index number in the space-frequency resource block(RB)twice and placing the in-phase and quadrature components of the diagonal code in different positions of the space-frequency code,respectively.According to the rank criterion of space-frequency coding,the proposed transmission algorithm obtains better bit error rate performance because the codeword design of the algorithm on each resource block makes the transmission diversity order of 2.Simulation results show that when the spectral efficiency is 1.78 bit/(s·Hz^(-1))and BER is 10^(-5),the TDA-QSFIM algorithm has a performance gain of about 3.5 dB compared with the QSFIM algorithm under independent Rayleigh channel,and when BER is 10^(-3) the TDA-QSFIM algorithm has a performance gain of about 5 dB over the QSFIM algorithm under the relative Rayleigh channel.