Throughput analysis for a contention-based dynamic spectrum sharing model

In this paper we present throughput analysis for a contention-based dynamic spectrum sharing model. We consider two scenarios of allocating channels to primary users, fixed allocation and random allocation. In fixed allocation, the number of primary users allocated to a channel is fixed all the time, but the number of users in different channels may be different. In random allocation, each primary user dynamically and randomly selects a channel in each time slot. We assume that the spectrum band of primary users is divided into multiple channels and the time is slotted. Primary users allocated to a specific channel compete to access this channel in each time slot. Secondary users are able to dynamically detect the idle channels in each time slot, and compete to access these channels. We develop analytical models for the throughput of primary users and secondary users in both scenarios and examine the impact of the number of secondary users on the throughput of the system. For a given number of primary users, channels and traffic generation probability, we aim to find the number of secondary users to maximize the total throughput of both primary users and secondary users. Our solutions match closely with the numerical results.