Effective Interference Nulling Virtual MIMO Broadcasting Transceiver for Multiple Relaying

In multi-hop relay networks, the improving end-to-end sum rate is a challenging issue. Although a new cooperative beamforming called virtual multiple-input multiple-output (MIMO) has been introduced as a possible solution, conventional virtual MIMO systems have severe signaling overhead among master and source nodes when the number of hops increases. To resolve this problem, a broadcast virtual MIMO system and a virtual MIMO broadcasting transceiver (VMBT) have been proposed to reduce the computational complexity and improve the end-to-end sum rate. However, the application of such methods is limited to environments wherein interference from other links and networks is not considered. Thus, it is difficult to apply them to practical multi-hop relay networks. In this paper, we propose a generalized version of the VMBT in which intra- and inter-network interferences are simultaneously caused by multiple transmission of clusters in the same network and each network's usage of the same frequency band, respectively. To achieve this goal, we propose an effective interference nulling VMBT scheme. Simulation results show that the proposed scheme has efficient performance in terms of average end-to-end sum rate compared with conventional schemes.