Energy Allocation Research On Energy Harvesting Based On Cooperation Relay Network

Wireless relaying and cooperation technology can resist path loss and multipath fading effectively, extend the coverage, increase the transmission rate and save transmission energy. As a new energy harvesting technology, Simultaneous Wireless Information and Power Transfer technology based on the nature of radio frequency signal that carry both information and energy can realize information and power transmission synchronously from terminal to terminal. Energy harvesting based on cooperation network, can increase the running time of the network and avoid shortcomings that the traditional wireless devices need replace the battery, due to network nodes collecting the energy from surrounding environment. Therefore, combining the advantages of energy harvesting and wireless cooperation, applying SWIPT to the wireless cooperation network, has become a new research focus. In this paper, we focused on wireless cooperation network with energy harvesting, and investigated the optimal power control and power transmission allocation problem in this network. The main contribution of this paper can be described as follows:(1) This paper obtain the optimal power control solutions for the three slots and two slots transmission mode in two-way relay system with SWIPT. For three slots relay system, based on the conclusion that system achieves maximum rate when the rate of the two-hop network is equal and under the situation that the channel gain of a two-hop network is different, the closed form solution of optimal power split ratio is given, which makes the system achieved maximum throughput. In two slots relay system, similarly, for different channel state information relationship of two-hop network, the optimal power split ratio is also derived, when the system achieved maximum rate. Finally, the simulations compare with the performance of the two systems model. It is found that the relay's position has a large impact on system performance, when the relay located in the middle position of the source and destination nodes, there is a case that three time slot bidirectional relaying is better than the two slots in system performance.(2) We proposed a power allocation strategy based on time-slot for a wireless cooperation network, where the user harvests energy from an energy access point(EAP) to power its information transmission to a data access point(DAP). Our objective is to minimize the energy that EAP transfer to the user, when satisfying the minimum rate requirement of user's wireless information transmission(WIT) link. Firstly, a causal control slot energy transfer strategy is proposed. Under the two circumstances that only satisfying user's rate requirement and joint considering rate requirement and battery capacity, then we obtain the system energy allocation strategy during each slot by using staircase water-filling(SWF) algorithm. Finally, under the same rate requirement constraint, numerical simulation results show that the proposed algorithm can make the system consume less energy than a conventional random power allocation.