Optimal Spectrum Sharing for Contention-Based Cognitive Radio Wireless Networks

Abstract

Fixed spectrum assignment policy lead to the need for a more dynamic approach to spectrum access. This paper analyzes the optimal dynamic spectrum sharing possibilities among primary and secondary users in cognitive radio networks, where the channel access for both primary and secondary users in the same channel is contention-based. We assume slotted time. Fixed and random allocations of primary users in the channels are considered for contention-based study. This means that in a fixed allocation, the number of primary users is fixed in a specific channel; their number may vary in different channels. Random allocation on the other hand considers primary users randomly allocated in different channels in each time slot. Given the number of channels and primary users, we find the optimal number of secondary users that obtains maximum throughput in spectrum sharing with primary users. The results obtained provide low complexity solutions for implementation in practical systems.