MDP-based handover policy in wireless relay systems

Wireless relay transmission has been considered as a supplementary technology for future wireless communication system, and handover is a key element in wireless relay transmissions to support users’ mobility. Handover failure will result in the forced termination of an ongoing call, and a good handover scheme will provide good system performance. This article focuses on the handover decision problem in wireless relay transmission systems. Initially, the architecture of a single-cell relay system is introduced. The handover decision problem is formulated as a Markov decision process (MDP). In the proposed model, a profit function is used to evaluate the quality-of-service of the chosen serving node, and a cost function is used to model processing load and signaling cost. Based on the profit and cost functions, the reward function is formulated. Moreover, the objective is to maximize the expected total reward per connection. The value iteration algorithm is employed to determine the optimal handover policy. Furthermore, the analysis is generalized to multi-cell relay systems. Numerical results show that the proposed MDP-based handover policy is well behaved in wireless relay systems.