An efficient algorithm to optimize interference and system capacity for cognitive wireless networks

In this paper, we study time spectrum block (TSB) assignment in cognitive radio networks. We consider a community cognitive radio network with a set of access points (APs), and formulate the TSB assignment as a quadratic integer programming (QIP) problem with an NP hard complexity. To avoid the NP-hard complexity, we propose a near-optimal heuristic algorithm LISTS (Least Interference and Switching based TSB Scheduling) that can be obtained at a much lower complexity. The algorithm is developed to solve this problem with the objective to minimize co-channel interference between APs (and their nodes) and channel switching overhead, and thus maximize system capacity. The LISTS algorithm offers near optimal solutions for TSB assignment. The overall system capacity increases by 40 % when compared with worst case of random TSB assignments.