MIMO Multi-Group Multi-Way Relaying: Interference Alignment in a Partially Connected Network

In this paper, a partially connected multi-group multi-way relay network is considered. Partially connected means that not all groups of nodes are connected to all relays in the network. However, any group is connected to at least one relay which serves this group of nodes. In such a network, each node wants to share a certain number of data streams with all other nodes in its group, but not with nodes in other groups. The most challenging part of such a network topology is the handling of the groups which are connected to multiple relays. This network topology can be represented as multiple subnetworks, where each of these contains one relay and all groups connected to this relay. In this paper, a new closed-form solution to achieve interference alignment is proposed. The relays are used to manipulate the effective channel in order to achieve interference alignment at each receiver. The concept of simultaneous signal and channel alignment is generalized in order to handle groups with more than two members. It is shown through simulation that the proposed interference alignment algorithm outperforms the reference algorithm in terms of sum rate and degrees of freedom.