2020/12/01 by Roy Karasik, Osvaldo Simeone, Karasik, Roy +5 · 1 citation
Engineering · #Advanced Wireless Communication Technologies #Satellite Communication Systems
paper · pdf · doi:10.48550/arxiv.2012.00407
A communication link aided by a reconfigurable intelligent surface (RIS) is\nstudied in which the transmitter can control the state of the RIS via a\nfinite-rate control link. Channel state information (CSI) is acquired at the\nreceiver based on pilot-assisted channel estimation, and it may or may not be\nshared with the transmitter. Considering quasi-static fading channels with\nimperfect CSI, capacity-achieving signalling is shown to implement joint\nencoding of the transmitted signal and of the response of the RIS. This\ndemonstrates the information-theoretic optimality of RIS-based modulation, or\n"single-RF MIMO" systems. In addition, a novel signalling strategy based on\nseparate layered encoding that enables practical successive cancellation-type\ndecoding at the receiver is proposed. Numerical experiments show that the\nconventional scheme that fixes the reflection pattern of the RIS, irrespective\nof the transmitted information, as to maximize the achievable rate is strictly\nsuboptimal, and is outperformed by the proposed adaptive coding strategies at\nall practical signal-to-noise ratio (SNR) levels.\n