Effect of time frame duration and collision on the performance of OFDMA-based cognitive radio network

In this paper, we assume that Secondary Users (SUs) opportunistically access to spectrum and model joint optimal sensing time, power and sub channel allocation problem in Cognitive Radio Network(CRN) under different types of collision caused when (1) spectrum sensing is imperfect and (2) Primary Users (PUs) return to network during Secondary User´s(SU´s) transmission. Our problem is modeled as mixed integer nonlinear program (MINLP). Since, MINLP models are amongst the most difficult optimization problems. We formulate two MINLPs: a base model, and a modified model via applying a series of mathematical and operational research techniques. Finally we examine two different case studies. The first case study is to highlight the advantages of our modified MINLP model. In the second case study, we focus on the frame duration effect on total secondary network throughput under different types of collisions. We find that the optimum frame duration can be adjusted based on traffic pattern to give higher throughput. Our findings and study here are to prepare a framework for multiframe transmission in CRNs.