Contract-based Spectrum Sharing And Data Offloading

In recent years, economic theories have been widely applied in the field of wireless communications. Many domestic and foreign scholars have been trying to use economic theories to solve the problems in wireless communication systems. As an important branch of economics, contract theory has also attracted lots of attention from the scholars in the field of wireless communications. Contract theory studies how economic subject deals with the information asymmetry problem by designing a proper contract. In wireless communication systems, information asymmetry is quite common. So, contract theory is particularly suitable for solving the problems in wireless communication systems.To settle the spectrum sharing problem in cognitive radio networks, we propose a new cooperative spectrum sharing scheme based on contract theory. In this scheme,there is information asymmetry between primary user and secondary user. We take into consideration secondary user’s energy-sensitivity, and classify secondary users into different types according to their own characteristics such as relay channel state,remaining energy and so on. Aiming at maximizing its utility, primary user offers secondary user a contract to employ it to work as a relay to help primary user transmit data. Meanwhile, on the premise of not degrading its own system performance, primary user can sell some spectrum access time to secondary users. In this scheme, we design a proper incentive mechanism to encourage primary user and secondary user to join the cooperative spectrum sharing system. Simulation results show that the proposed scheme can not only improve the spectrum eficiency, but also provide spectrum access opportunities to secondary users and significantly improve primary user’s utility.In addition, we propose a novel contract-based data offloading scheme to solve the offloading problem in wireless cellular networks. In Macrocell and WiFi/Small Cell based two-tier heterogeneous networks, there is information asymmetry between the Internet Service Provider and users. We classify users into different types according their percentages of mobile data trafic offloaded to the WiFi or Small Cell networks.The contract the Internet Service Provider offers to its users consists of a series of data plans, and each user can choose one proper data plan according to its own type. In this scheme, the design method of optimal contract under asymmetric information scenario is given. Simulation results show that the proposed scheme can not only greatly improve the Internet Service Provider’s utility, but also achieve the goal of data offloading effectively. Meanwhile, our scheme encourages the Internet Service Provider to offer better WiFi/Small Cell network service to improve its utility.