Interference Cancellation and Energy Harvesting Techniques for Cooperative Spectrum Sharing Cognitive Radio Systems

With the exponential increase in wireless applications, there arises the need to utilize the spectrum more efficiently. Cooperative spectrum sharing (CSS) schemes have been proposed as a viable framework for cognitive radio where, an unlicensed (secondary) user can access the spectrum of licensed (primary) user, on the condition that unlicensed user will help the licensed user in achieving the target rate of communication. While sharing the spectrum, primary user always has higher priority. In the proposed work, a two phase CSS scheme is proposed, where secondary’s transmitter equipped with multiple antennas uses transmit antenna selection to improve the primary’s performance by reducing the interference level of secondary signal at primary receiver. Moreover, a three phase interference cancellation CSS scheme using STBC (Space time block code) is also proposed. It has been shown that the proposed scheme helps in achieving diversity gain of three and two for primary and secondary system respectively. Apart from above, we have also proposed a novel approach to solve the power issues in secondary user by utilizing technique such as RF (radio frequency) energy harvesting. Specifically, we have shown that significant performance gains can be obtained for both primary and secondary user by using RF energy harvesting.