Advanced Wireless Communications: A Physical Layer Perspective

After years of advances and developments in telecommunications industry, mobile cellular systems are becoming mature. Physical layer was at the forefront of rapid changes in the previous decades and still remains an important research area in new technologies such as Cognitive Radio, Spectrum Sharing, Energy Harvesting and Wireless Powered Communications etc. Cognitive Radio has emerged as one of the most promising technologies to resolve the issue of spectrum scarcity, caused by the escalating growth in wireless data traffic. The concept of spectrum sharing was originally proposed in cognitive radio networks to allow secondary (unlicensed) users to opportunistically access the temporally or spatially unused spectrum bands of the primary (licensed) users. Energy harvesting technique through radio frequency transmissions seems to be a very promising solution to power hungry applications such as wireless sensor networks where limited lifetime degrades the performance of the network.