High performance bit‐activation code index modulation method

Abstract

With the increasing demand of applications for the spread spectrum technique, especially the demand for data transmission rates and spectral efficiency, the advantages of the traditional direct sequence spread spectrum (DSSS) system are limited. Therefore, multi‐ary spread spectrum (M‐ary) technology, parallel combinatory spread spectrum (PCSS) technology, and code index modulation (CIM) technology have been proposed. Although these three new technologies can improve the data rate, they all face the problem of the large consumption of pseudo‐code resources. In order to solve the problem of pseudo‐code resources, a bit‐activation code index modulation (BA‐CIM) method is proposed. At the transmitter, considering the good correlation among multiple pseudo‐codes, the corresponding pseudo‐code activation principle is established, and the corresponding spreading pseudo‐code is activated by using the status of each bit of the index data according to the pseudo‐code activation principle. Then, multicode superposition processing is carried out to spread the modulation data. At the receiver, the corresponding activation pseudo‐code is obtained using the maximum peak‐to‐average ratio (MPAR) and secondary peak‐to‐average ratio (SPAR) judgement mechanisms to decode the multibit index data. Compared with existing methods, the proposed BA‐CIM method can not only achieve a better bit error rate performance but also use the least pseudo‐code resources. Moreover, BA‐CIM has the best comprehensive performance improvement and is far superior to other methods. This research can provide technical support for the application of efficient spread spectrum communication.