System Design Of Low Complexity In Wireless Powered Communication Networks

With the development of the technology and industrial application of wireless sensor, the traditional method of battery charging is no longer suitable for wireless network of energy-constrained sensor, and the it is an urgent problem that how to get the battery charged without disembowel the battery. Consequently, construction of green wireless communication system with high energy efficiency is the frontier topic of great importance in wireless communication field, and energy harvesting based on wireless energy transmission technology (WET) becomes very attractive and innovative.Because radio waves can carry energy and information at the same time, simultaneous wireless information and power transfer system (SWIPT) emerges. However, many studies focus on the wireless powered communication network (WPCN) due to the difficulties coming from the hardware of SWIPT system. The experts and scholars of domestic and foreign companies, universities and research institutes show great interests on the application of WPCN. They also throw light on the energy transfer mechanism, system design and performance analysis of the WPCN. At the same time, the research of the WPCN is still on the initial stage, which is in the need of further exploration.On the one hand, most of the proposed optimal algorithms were of high complexity though the existing literatures provided system design aiming to the system performance. As the WPCN system transmits energy with low efficiency, the design of low complexity systems requires further study. On the other hand, it was assumed that the system had the knowledge of the perfect channel state information in most of the existing system design literatures, which was impossible since obtaining the channel state information would assume much energy in practical application. Therefore robust WPCN system design needs be paid more attention in case of the channel state information with estimated error.Based on these two aspects, this paper concentrates on low complexity design of single-input single-output (SISO) and multi-input single-output (MISO) WPCN system design. In the SISO WPCN system, we study the time allocation problem to maximize the system sum-throughput. Due the near-far problem (i.e., user with the lager channel gain is allocated more time), the problem of maximizing the minimal user’s throughput is formulated and the fast time allocation algorithm is further studied respectively, then the performance and time complexity of the proposed fast algorithm is verified by simulation results. Algorithm of time allocation and beamforming design is researched in the multiple-input single-output WPCN system. In the case of the system knowing the channel state information, fast algorithm is given of the sum-throughput maximization problem. While in the case of estimated error of the channel state information existing, robust algorithm is studied with the subject of signal to noise ratio (SNR) outage probability, which is also demonstrated by simulation results.