Multiuser Two Way Relaying Schemes in the Future Cellular Network

We propose a set of multiuser two-way relay beam-forming schemes in the cellular network. While the previous schemes are applicable only when there exist a single base station (BS) and a single relay station (RS) with the same number of antennas, multiple BSs or multiple RSs can exist in the proposed scheme without such restriction on the numbers of antennas. The degree of freedoms (DoF) achievable are analyzed and conditions to achieve these DoF values are presented. Both the decode-and-forward (DaF) protocol and amplify-and-forward (AaF) protocol are considered. It turns out that the channel alignment and the interference alignment in the multi-cell environment act the key roles in the development. We also provide an interference alignment scheme in the multi-cell environment that improves the achievable DoF values upon those of the previous schemes. The simulation results corroborate that the proposed beam-forming works as analyzed.