IRS-Assisted Extended Variable Spatial Modulation: A High Spectral Efficiency Scheme

Intelligent reflecting surface (IRS) has been proposed as a promising candidate technology for next generation communication network, due to its superiority in reliable and high quality communication. In this letter, we propose a novel communication scheme that combines IRS with index modulation (IM) to achieve high spectral efficiency (SE), which is named IRS-assisted extended variable spatial modulation (IRS-EVSM). In the proposed scheme, the number of active antennas is determined by different transmission modes in each time slot, while IRS is divided into a number of sub-surfaces. To avoid the detection ambiguity at the detector, each transmission mode has its own modulation orders. Meanwhile, the theoretical upper bound of average bit error rate (ABER) based on maximum likelihood (ML) detector is proposed. Moreover, the impact of imperfect channel state information (CSI) on the system performance is investigated. Simulation results show the bit error rate (BER) performance of IRS-EVSM is better than those of IRS-RSM and IRS-RGSM schemes, and it can achieve higher SE under the same antenna setting.