RIS-Assisted Spatial Modulation and Space Shift Keying for Ambient Backscattering Communications

In wireless communications, reconfigurable intelligent surfaces (RIS) are emerging as a promising technology that is made possible by the advent of software controlled metamaterial sheets for controlling the wireless channels dynamically. In future applications, IoT devices will have small sizes and limited power supply. To make these devices spectrally and energy efficient in accordance with the advanced 5G and 6G specifications, we propose ambient backscattering (ABSc) technique along with spatial modulation (SM) and space shift keying (SSK) for data transfer assisted with RIS. We also conduct a thorough performance analysis of these schemes in terms of outage probability, and bit error rate, validated by Monte-Carlo simulations, and provide comparative results that illustrate the merits of the proposed techniques. In particular, it is shown that RIS-empowered SM and SSK along with ABSc perform much better than conventional communications.