طرح تخصیص منابع بهینه برای شبکه های شناختی رادیویی با انتخاب رله بر اساس تئوری بازی

In this paper, we present a non-transferable utility coalition graph game (NTU-CGG) based resource allocation scheme with relay selection for a downlink orthogonal frequency division multiplexing (OFDMA) based cognitive radio networks to maximize both system throughput and system fairness. In this algorithm, with the assistance of others SUs, SUs with less available channels to improve their throughput and fairness by forming a directed tree graph according to spectrum availability and traffic demands of SUs. So this scheme can effectively exploit both space and frequency diversity of the system. Performance results show that, NTU-CGG significantly improves system fairness level while not reducing the throughput comparing with other existing algorithms.

Nowadays facing the problem between increasing bandwidth demands and underuse of licensed spectrum, cognitive radio (CR) has been proposed as possible approach for secondary users (SUs). Due to the possible changing environment sensed by different SUs in different location, a common available channel for a pair of SUs may be difficult to confirm. In order to solve above problem, cooperative relay has been introduced into CR networks [1]. With the assistance of other SUs, some of non-common spectrum bands can be bridged to exploit more spectrum opportunities. Then how to get optimal resource allocation with consideration on feasible relay selection scheme has attracted extensive interests recently for higher spectrum utilization [2–4]. In this paper, we study the optimal resource allocation with relay selection for a downlink orthogonal frequency division multiplexing (OFDM) cognitive radio network (CRN). The main contribution is to model this problem as a NTU-CGG, and propose a low-complexity algorithm for coalition graph formation to maximize SUs’ utility while guaranteeing their fairness. The rest of the paper is organized as follows. Sect. 2 describes the system model and problem formulation. Sect. 3 shows a low-complexity algorithm for coalition graph formation. Simulation results locate in Sect. 4, and conclusions are in Sect. 5.

In this paper, we study the problem of optimal resource allocation with relay selection and in overlay downlink cognitive relay network. This problem is formulated as a coalition graph game problem to maximize both the system capacity and fairness. Then we proposed a heuristic low-complexity algorithm to implement the coalition graph formation. The NTU-CGG approach consists of three phases, which are preformatted according to users’ spectrum availabilities. Results show that, the proposed algorithm outperforms other algorithms in terms of both throughput and fairness while adapting the topology to environment changes.