The Research On Power Allocation And Relay Selection Algorithm In Energy Harvesting Cognitive Relay Networks Electronic And Communication Engineering

Energy harvesting(EH) is a promising technique for cognitive relaying network(CRN) where secondary users(SUs) and relaying nodes do not have a constant power supply each, the energy harvesting nodes can harvest the energy from the noise and interference from the environment for communication. In energy harvesting networks,we can improve the transmit power of SUs to optimize the data rate, which increases the energy consumption at the same time. The harvested energy of nodes is limited,and the energy consumption influent the communication lifetime of SUs directly, so we have to consider the energy consumption and energy efficiency in the process of optimizing the end-to-end(e2e) data rate.The power allocation and relay selection algorithm in energy harvesting cognitive relay network is proposed, whose objection is to maximize the energy efficiency and data rate. In particular, the channel states, spectrum states and energy states of each node(either a SU or a relay) are modeled as finite-state Markov chains.And the transmit power at a node is optimally allocated by jointly accounting for the interference threshold prescribed by primary users(PUs), the maximum transmit power and the harvested energy. The optimization problem can be readily solved by use of the Lagrange function and classic Karush-Kuhn-Tucker(KKT) conditions. In addition, the thesis puts forward a new relay selection criterion by taking both channel states information(CSI) of relaying links and energy states at relaying nodes into account to choose the best relay for signal forward and improve the communication performance of SUs. With extensive Monte-Carlo simulation results, the developed power allocation and relay selection algorithm based on data rate maximization is shown to outperform the existing ones in the open literature, in terms of the e2 e data rate. The joint power allocation and power allocation based on energy efficiency obtains higher system utility in lower transmit power, improves the energy efficiency and reduces outage probability.