Signal Constellation Construction via Radio Frequency Mirrors

Abstract

By integrating feedback with Radio Frequency (RF) mirrors, we develop a closed-loop media-based modulation system for efficient utilization of the signal space. Specifically, this closed-loop construction optimizes the inherited signal constellation from the media, achieving a significantly larger minimum pairwise Euclidean distance than the original configuration. The initial signal constellation, derived from the media, is used to compute a set of complex weights for all activation patterns of the RF mirrors. These complex weights are then fed back to the transmitter to refine the transmit signal before it reaches the mirrors. This feedback mechanism ensures that the received, shaped signal constellation retains improved properties, enabling more reliable transmission. Notably, the closed-loop approach enables the media-based modulation to approach the performance of an AWGN channel, while the channel from each mirror to the single-antenna receiver is modeled as Rayleigh fading.