Ali Kariminezhad

Power efficiency of improper signaling in MIMO full-duplex relaying for K-user interference networks

Multi-hop communication is a spectral-efficient approach for connecting multiple pairs when direct links are absent or have insufficient strength. In this paper, we highlight the benefits of improper Gaussian signaling for a multi-pair full-duplex MIMO relay network in terms of power efficiency. By employing improper Gaussian transmission, the power minimization problem under rate constraints is intrinsically a non-convex problem due to non-convex rate expressions in the constraint set. We utilize Fenchels inequality to linearize the non-convex part of the constraint, which results in feasible solutions of the problem in polynomial time. This approximation results in an upper-bound for the original problem which gets tighter in the number of iterations performed. The solution is compared with analytical beamforming solutions, namely zero-forcing (ZF) and maximum-ratio transmission/combining (MRT/MRC). Due to the feasibility of single rank real-valued transmission in improper Gaussian signaling, the optimal solution switches to single rank transmission depending on the constraints defined by the requests of the users, which can not be captured by proper Gaussian signaling.

Optimal Power Splitting for Simultaneous Information Detection and Energy Harvesting

This letter deals with the joint information and energy processing at the receiver of a point-to-point communication channel. In particular, the tradeoff between the achievable information rate and harvested energy for a multiple-antenna power splitting receiver is investigated. Here, the rate-energy region characterization is of particular interest, which is intrinsically a nonconvex problem. In this letter, an efficient algorithm is proposed for obtaining an approximate solution to the problem in polynomial time. This algorithm is mainly based on the Taylor approximation in conjunction with semidefinite relaxation, which is solved by interior-point methods. Moreover, we utilize the Gaussian randomization procedure to obtain a feasible solution for the original problem. It is shown that by proper receiver design the rate-energy region can be significantly enlarged compared to the state of the art, while at the same time the receiver hardware costs is reduced by utilizing less number of energy harvesting circuitry.