Cramer-Rao bounds for MIMO LOS systems affected by distributed Wiener phase noise in the large-blocklength regime

In this paper, we compute the Bayesian Cramér-Rao bound for a MIMO line-of-sight system with independent equal oscillators at each antenna and Wiener phase-noise model. In particular, we consider the case where the blocklength is large enough and derive analytical expressions for the bound in the middle of the block. The results distinguish between phase detectors that can use both past and future samples (smoothers) and phase detectors that are bound to use only past samples (filters). Simulation results show that the performance dictated by the bounds can be achieved within a 2-dB SNR gap.