Two-way Code Index Modulation

Abstract

In this study, a new code index modulation (CIM) aided two-way network coded (TW-CIM) scheme with high energy-efficiency, high data speed and good error performance is proposed. In the proposed system model, unlike conventional decode-and-forward (DF) cooperative network coded communication techniques that perform three time-interval communications, only two time-intervals are used for communication since the spreading codes used are orthogonal to each other. In the proposed system structure, as well as the transmitted modulated symbol data, the spreading code indices carry data. In the TW-CIM system, two different users communicate via a half-duplex relay based on the CIM technique. The considered TW-CIM system has been compared with the cooperative TW-DF system at different data rates. The theoretical error analysis of the proposed system is performed and the average bit error probability is achieved. Performance analyzes have been performed on Rayleigh fading channels for BPSK modulation.