Wireless body area networks (WBAN) require long life links and energy efficient system. Besides the increasing commercialization of WBAN, health monitoring applications calls for enhanced quality of service (QoS). The establishment of the reliable and energy efficient link is crucial to support the improvement of the WBAN performance parameters. In this article, we propose a cross-layer routing mechanism for WBAN quality of service enhancement. The protocol uses a cost function, which linearly combines node energy ratio, link reliability, and specific absorption rate functions. The proposed algorithm initially maximizes network lifetime longevity by reducing node energy consumption with nearly reasonable throughput and the packet delivery ratio whereas the enhancement of the QoS focused on improving network throughput and the packet delivery success rate for WBAN applications. The algorithm is implemented in two stages, firstly by designing the energy efficient and reliable link routing policy in the network layer and secondly the adjustment of the contention window for QoS performance enhancement in the data link layer using IEEE 802.11 medium access control (MAC) protocol. We conduct parametric modeling of the cost function to analyze network performance in different parametric combinations and contention window adjustments. Simulation results show the proposed protocol improves network performance indicators such as energy efficiency, lifetime longevity maximization, throughput, packet success delivery ratio, reduced end to end delay, and routing overhead.

This paper studies the joint beamforming design and time allocation for a two-way energy harvesting (EH) relay network, where a single-antenna base station and a single-antenna user communicate with each other through multiple-single antenna EH relay nodes, and an external multiantenna power beacon wirelessly power the relays. Unlike the existing studies that assumed the symmetric two-way relaying scenario, we assume a more practical scenario of asymmetric two-way relaying considering different traffic demands on the downlink and uplink. In this paper, we design the optimal beamforming vectors at the relays and at the power beacon jointly with the time allocation between information and EH transmissions, in the sense of maximizing the sum rate of the asymmetric information transmission under the EH constraints at the relays, and the power constraint at the power beacon. The formulated optimization problem is nonconvex, and thus, it is difficult to solve. To solve this challenging problem, we propose an iterative algorithm based on the semidefinite relaxation and the successive convex approximation techniques. Also, to reduce the computational complexity, we propose an efficient noniterative scheme based on the maximum-ratio transmission. The performance of the proposed schemes is demonstrated through simulations.