Abstract
Recently, a variant of network coding at the physical layer named wireless network coding (WNC) has gained much attention due to it’s simplicity and capacity improvement of a bi-directional link. In this paper, we design and analyze a bi-directional cognitive radio (CR) system with multiple pairs based on WNC while taking into account the imperfect spectrum sensing and interference from/to the CR system. In addition, we design a resource allocation framework consisting of a subcarrier allocation strategy with different priority assignments and optimal power allocation algorithm. We show that the quality of service within the CR system highly depends on a proper design of the spectrum sensing process to minimize the probability of missed detection, while the spectrum efficiency of the CR system increases with the number of pairs within the system to which we assign priorities.
Highlights
A limited frequency spectrum is becoming a major problem to accommodate demands of new broadband wireless Internet services such as video streaming, video conferencing, and network gaming
A cognitive radio (CR) was proposed [2], where the spectrum not used by primary users (PUs) is allocated to secondary users (SUs)
With different subcarrier allocation algorithms, we evaluate the impact of the chosen priority policy on the total throughput of the CR system in the presence of power and interference constrains
Summary
A limited frequency spectrum is becoming a major problem to accommodate demands of new broadband wireless Internet services such as video streaming, video conferencing, and network gaming. A bi-directional CR system [5,6] with multi-antenna relay was presented to improve the spectrum efficiency while keeping the interference towards the PUs in tolerable limits in the case of frequency flat fading channels. We design and analyze a bi-directional CR system with multiple SU pairs enabled by WNC while assuming imperfect spectrum sensing and interference from/to the CR system. Because of the imperfection of spectrum sensing, some of the detected unoccupied (i.e., white) subcarriers may be used for primary transmission causing interference to the CR system. The communication protocol is initiated over the selected set of white subcarriers
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