Publication Date:
2018-01-03
Description:
We study the degrees of freedom (DoFs) of a multiple-input multiple-output $K$ -pair two-way relay channel with delayed channel state information (CSI) with $J$ distributed relays. In the considered model, we assume that the users are equipped with $M$ antennas and the relay with $N$ antennas. We propose two schemes, where the signaling design can be carried out either in each individual time slot or across multiple time slots with and without knowledge of CSI. The scheme involves a joint design of user beamforming matrices, relay beamforming matrices, and user postprocessing matrices, so as to meet interference neutralization and rank conditions. We show that the optimal DoF of $frac{N}{2K}$ per user can be reached for $frac{M}{N}geq 1$ for an arbitrary number of user pairs when $J=1$ . This implies that delayed CSI does not compromise the DoF performance of the considered model when $frac{M}{N}geq 1$ .
Print ISSN:
1070-9908
Electronic ISSN:
1558-2361
Topics:
Electrical Engineering, Measurement and Control Technology
