Wireless information and energy transfer in multi-cluster MIMO uplink networks through opportunistic interference alignment

In this paper, we consider a K-cluster (K ≥ 2) simultaneous wireless information and power transfer network, where S nodes (S ≥ 2) are selected from N nodes within each cluster for the uplink information transmission and the remaining N - S idle nodes are dedicated to energy harvesting. Based on the intra-cluster performance aware (ICPA) philosophy, a pair of opportunistic interference alignment (OIA) schemes, namely, the coarse ICPA-OIA (C-ICPA-OIA) and the refined ICPA-OIA (R-ICPA-OIA), are proposed for balancing the sum rate performance achieved and the energy harvested. Specifically, the C-ICPA-OIA treats the overall signal strength within the reference signal subspace (RSS) as a coarse description of the node's effective signal strength. By comparison, to take full advantage of zero-forcing-based reception, the R-ICPA-OIA considers the projected signal strength with respect to the orthonormal basis of RSS as a substantially refined description of the node's effective signal strength. Furthermore, we analyzed the harvested power and the working time of the system. Extensive simulation results validate our theoretical analyses, demonstrating that our schemes outperform the existing OIA schemes.