Study On Optimal Transmission Strategy For Simultaneous Wireless Information And Energy Transfer In MIMO Relay Channels

The wireless communication system with renewable energy is the future development trend of green mobile communications. The wireless transmission system which have energy harvesting can collect solar energy, wind energy and energy of radio frequency signal. Energy harvesting is a promising solution to increase the life cycle of wireless nodes and hence alleviates the energy bottleneck of green wireless networks. As one of the most representative in EH technology, Simultaneous Wireless Information and Power Transfer technology would solve the defect of the Wireless nodes often cann’t equip reliable power supply. Combining Multiple-Input-Multiple-Output technology and the relay technology, it will improve the efficiency of information transmission rate and energy transmission reliable. In view of this, this article study on optimal transmission strategy for simultaneous wireless information and energy transfer in MIMO relay channels, the main research points due to the following two aspects;(1) Antenna switching in SWIPT; two users with multiple antennas communicate with each other assisted by an energy harvesting MIMO relay that process signal and power transmission by applying antenna switching scheme. Firstly, the system can be divided into two phase. And we use the singular value decomposition method and water flooding algorithm to optimize precoding matrix of two phase. In the second phase, the relay node’s sending power is limited by the first phase’s energy harvesting, and sum rate of system is restricted to relay’s forwarding protocol. In order to balance the relay node’s information transmission rate and energy transfer efficiency, this paper calculate the antenna selection and optimization scheme by the exhaustive method, It can reasonable allocate the resources and improve the sum rate of system. The simulation results show that optimal antenna switching scheme greatly improved the sum rate of system. Finally, we optimize allocation of system’s time resources to delicate increase sum rate of system. The simulation results also show that time resources optimal improved the sum rate of system again.(2) Time switching in SWIPT; Compare with(1), the energy harvesting MIMO relay that process signal and power transmission by applying time switching scheme. And the system communication process is divided into three time slots. Firstly, we formulate the resource allocation optimization problem. We make the system rate maximization problem decomposed into several convex optimization sub-problems. Then, it is focused on the pre-coder design and resource allocation strategies for the system to allocate the resources among the nodes in Decode-and-Forward(DF) mode. The closed-form solutions for the time and power allocation are derived. It is revealed that the solution which combine time resource allocation and pre-coder design can flexibly allocate the resource for the MIMO relay channel to maximize the sum rate of the system. Simulation results demonstrated that the performance of the proposed algorithm outperforms the traditional fixed method.