Utility maximization of three phase spectrum leasing scheme using Stackelberg game

Cognitive Radio (CR) is a promising technology to alleviate spectrum scarcity problem. CR enables a technique called spectrum leasing where the secondary users able to access licensed spectrum bands opportunistically by making monetary payment. A three phase spectrum leasing scheme is considered where primary user allows users in a distributed secondary network to access its licensed band either in underlay or overlay CR transmission manner. A network of multiple users competing for the same idle spectrum ends up causing intolerable interferences to the primary receiver. An improved interference alignment technique is incorporated to reduce the effect of interference at primary receiver while maximizing the SINR at each receiver. Since the idle spectrum of PU is a valuable commodity and many users are competing for the same time, there arises conflict among them in taking decisions. This issue is resolved using game theory. The problem is formulated under Stackelberg game framework and optimal strategies are found out at the equilibrium. Using these optimal strategies, it is found out that the utility of users is improved. Simulations are carried out to study the proposed system and an improvement in performance is observed under various network conditions.