Contract Design for Traffic Off-Loading Collaboration in H-CRAN with Asymmetric Information

Shutting off the small base stations (SBSs) with low traffic load is a promising approach to save energy, and how to incentive the SBSs nearby to cooperate and take over the traffic is an important problem, especially when these SBSs belong to different service providers and have different benefit targets. In this paper, we assume the channel state information (CSI) of both the access link and the fronthaul link of a potential off-loading SBS (oSBS) is unavailable to the shutting down SBS (sSBS). Under such an asymmetry information condition, contract theory is exploited to encourage the nearby oSBSs to take over the traffic- load and help the sSBS select an appropriate oSBS. Such an off-loading cooperation stimulation problem is formulated into a contract design problem, where the sSBS is the principal and the oSBSs are agents. Through theoretical analysis, we simplify the constraints of the formulated problem, and derive the optimal solution, i.e., the optimal contract, for the scenario where the CSI of the access link and fronthaul link of an oSBS are both quantized into two levels. Numerical results validate that the proposed contract-based incentive scheme is effective for improving the utilities of both the oSBS and sSBS.