On upper bounds for decentralized MIMO receiver

In this paper we investigate the achievable rate of a system that includes a nomadic transmitter with a Gaussian codebook and several antennas, which is received by multiple agents, each with a single antenna, suffering independent channel gains and additive Gaussian noise. In the nomadic regime, we assume that the agents do not have any decoding ability. These agents process their channel observations and forward it to the final destination through lossless links with fixed capacities. This paper extends a previous work [1] by providing new upper bounds on the achievable rates, and demonstrates optimality of the suggested coding scheme in several asymptotic situations. For a finite 2 x 2 setting and Rayleigh fading, the upper-bounds for both fast and block fading are demonstrated.