Relay-assisted beamforming for multicast systems with energy harvesting capability

In this paper, multi-group multicasting scenario is considered where single antenna sources transmit their own information to different groups of users with the help of single antenna relays. Users have energy harvesting capability, i.e., a part of the received signal is used for information decoding while the rest is used for energy harvesting. Beamforming is performed by the relays which use amplify-and-forward protocol. The design of complex relay coefficients and power splitting ratios for the users is studied and the resulting nonconvex optimization problem is converted into a form suitable for quadratically constrained quadratic programming. In this paper, phase-only beamforming is also considered and both problems are solved iteratively.