Code Index Modulated Chaotic Ambient Backscatter Communication With Differential Walsh Codes

This letter proposes a code index modulated chaotic ambient backscatter communication (CIM-CAmBC) over Rayleigh fading channels. In this system, multiple bits of the backscatter device can be transmitted in a radio frequency (RF) source symbol by using CIM technique. Moreover, we design a differential Walsh code matrix for CIM at the backscatter device such that direct-link interference (DLI) can be effectively eliminated at the reader without acquisition of channel state information (CSI). The theoretical error performance of the proposed CIM-CAmBC over multipath fading channels is derived and then verified by simulations. The results demonstrate that the proposed system can outperform the conventional DCSK-AmBC and CIM-DCSK-AmBC by more than 3 dB over fading channels.