Contract Theory Based Incentive Mechanism Design Approaches in Cognitive Radio Networks: A Survey

Through the previous decade, an ever increasing demand of wireless radio spectrum has been observed due to expeditious use of various wireless applications and devices. However, current fixed radio spectrum policy holds up the efficient use of radio spectrum due to which large part of the spectrum remain under-utilized. This requires a complete transformation of how currently spectrum is managed, from fixed spectrum assignment to dynamically accessing the spectrum. This step will help to considerably minimize the burden on bounded spectrum resources due to the expanded growth of wireless services. Recently, cognitive radio networks technology is gaining much attention due to its ability to use the spectrum more intelligently and flexibly. This technology of cognitive radio allows unlicensed users to exploit the idle spectrum channel dynamically while licensed users are not transmitting. This requires participation and agreement of licensed user to allow the use of their resources by the unlicensed users opportunistically. Thus, new incentive design mechanism in cognitive radio networks is required such that participation of licensed user nodes is ensured. Contract theory is an incentive design mechanism where participants are offered appropriately designed reward to encourage cooperation. To achieve this, the interaction between the licensed users and unlicensed users is modeled as a labor market using contract theory. In this work, first introduction to cognitive radio networks is provided followed by the survey of use of contract theory in the Next Generation Wireless Networks in the literature. The work is concluded with the possible future directions in this area.