非正交码移键控和码索引调制算法

针对正交码移键控(code shift keying, CSK)误比特率(bit error rate, BER)性能下降和非正交码索引调制(non-orthogonal-code index modulation, N-CIM)未能充分利用扩频码自相关性的不足,提出一种非正交CSK和码索引调制(non-orthogonal-CSK-code index modulation, N-CSK-CIM)算法。发送端信息比特分为调制比特和扩频码映射比特；调制比特用来进行符号调制，映射比特映射为扩频码的索引和码相位索引。首先根据调制比特进行符号调制，然后利用映射比特映射的扩频码索引选择同一原始扩频码，并根据码相位索引进行码移键控产生新的扩频码，调制后的符号实部与虚部分别用这一新的扩频码进行扩频。仿真结果表明,在加性高斯白噪声(additive white Gaussian noise, AWGN)信道和瑞利衰落信道中,相同信噪比时, N-CSK-CIM算法的BER性能优于N-CIM算法和正交CSK算法。

Algorithm for non-orthogonal code shift keying and code index modulation

To deal with the problem that the bit error rate(BER) performance degradation of orthogonal code shift keying(CSK) and the insufficiency that the non-orthogonal-code index modulation (N-CIM) cannot make full use of the autocorrelation of spread spectrum codes, an algorithm of the non-orthogonal-CSK-code index modulation (N-CSK-CIM) is proposed. The information bits of the transmitter are divided into modulation bits and spread spectrum code mapping bits; Modulation bits are used for symbol modulation, and mapping bits are mapped into spread spectrum code index and code phase index. Firstly, the symbol is modulated according to the modulation bits. Then, the same original spread spectrum code is selected by using the spread spectrum code index mapped by the mapping bits, and the new spread spectrum code is generated by code shift keying according to the code phase index. The real part and imaginary part of the modulated symbol are spread spectrum with this new spread spectrum code respectively. Simulation results show that the BER performance of N-CSK-CIM algorithm is better than that of N-CIM algorithm and orthogonal CSK algorithm in additive white Gaussian noise (AWGN) channel and Rayleigh fading channel with the same signal to noise ratio.