Transmitter Switching Algorithms For Energy Harvesting Wireless Communication Systems

Energy harvesting wireless communication systems attracted great research attentionin recent years as the battery technology developed. To minimize transmission completiontime in energy harvesting wireless communication systems, various transmissionscheduling schemes have been proposed. However, researchers did not consider the issuewhere a transmitter may fail before completing the transmission. When a transmitter isbroken or the energy harvested by a transmitter is insufficient, a transmitter switchingalgorithm is developed to choose a suitable transmitter to work whenever necessary. Toobtain this transmitter switching algorithm, the system with two energy harvestingswitching transmitters and two users, the system which consists of multiple energyharvesting switching transmitters and one receiver, and the system consisting multipleenergy harvesting switching transmitters and multiple receivers are studied respectively.The main contributions are listed as follows:In the system with two energy harvesting switching transmitters and two users, thetransmitters harvest energy in dependently and work alternately. The transmissionscheduling problem is formulated as minimizing the transmission completion time, underthe energy causality constraint, the data transmission constraint, and the transmitterswitching constraint. Transmitter switching is addressed by proving that a transmittershould not stop transmission before switching to the other transmitter and the switchingthreshold should be zero. Then, an optimal switching algorithm is proposed based onearlier works on rate region and the transmitter switching mechanism. The proposedoptimal switching algorithm can achieve a larger rate region than several kinds ofsuboptimal ones.In the system which consists of multiple energy harvesting switching transmitters andone receiver, a geometric projection-based transmitter switching algorithm is proposed,which can reduce the number of switches. The results show that the proposed transmitterswitching algorithm leads to a lower number of switches than several heuristic ones.In the system consisting multiple energy harvesting switching transmitters andmultiple receivers，First, regarding the transmitters as a`whole transmitter’, the optimaltotal transmission power and the optimal power allocation policy are obtained, with theaim of minimizing the transmission completion time. Then, a simpler power allocationalgorithm is developed to allocate the optimal total transmission power to the datatransmissions. A transmitter switching algorithm is further developed to choose a suitable transmitter to work whenever necessary. The results show that the proposed powerallocation algorithm performs close to the optimal one and outperforms some heuristicones in terms of transmission completion time. Besides, the proposed transmitter switchingalgorithm outperforms some heuristic ones in terms of number of switches.The energy harvesting wireless communication systems with switching transmittersare resilient and robust, high efficiency of energy and low number of transmitter switches.