Spectral-efficient design in modern wireless communications networks

• Main Author: Lu, Lu
• Other Authors: Li, Geoffrey Ye
• Format: Others
• Language: en_US
• Published: Georgia Institute of Technology 2015
• Subjects: Wireless communications; Cognitive radio; Spectral efficiency; Spectrum sensing; Spectrum access mode; Spectrum overlay; Spectrum underlay
• Online Access: http://hdl.handle.net/1853/53902

We investigate spectral-efficient design and develop novel schemes to improve spectral efficiency of the modern wireless communications networks. Nowadays, more and more spectrum resources are required to support various high-data-rate applications while spectrum resources are limited. Moreover, static allocation and exclusive access in current spectrum assignment policy caused a lot of licensed spectrum bands to be underutilized. To deal with the problem, cognitive radio (CR) has been developed, which allows unlicensed/secondary users to transmit with licensed/primary users as long as the former ones do not generate intolerable interference to the latter ones. The coexistence of users and networks requires careful and dynamic planning to mitigate interference. Otherwise, the network performance will be severely undermined. We study both spectrum sensing and spectrum access techniques and propose several transmit schemes for different types of cognitive ratio networks, including spectrum overlay and spectrum underlay systems. The proposed algorithms can improve spectral efficiency of the networks efficiently and have potentials to be used in future wireless communications networks.