Design of an Enhanced Handover Algorithm Based on a New Adaptive SR-ARQ for Next-Generation Mobile Communication Networks

Next-generation mobile communication networks are supposed to provide various high capacity multimedia services to mobile users using various kinds of access networks. Among them, the WiNGS system developed by ETRI as one of 4G mobile system provides high performance RATs (Radio Access Technology) and network architecture with IP connectivity for merging them. In this paper, we propose a new link layer Selective-Repeat Automatic Repeat Request (SR-ARQ) mechanism that solves packet re-ordering problems during handovers and enhances handover performance in WiNGS system. In the proposed mechanism, we adopt an adaptive timer in the sending node in order to prevent unnecessary packet retransmission during handovers, and a delayed NAK scheme in the receiving node to prevent detection of temporal packet reordering due to handover delay. We implemented the proposed SR-ARQ mechanism in ns-2 simulator for performance evaluation. The simulation results show that the proposed SR-ARQ enhances handover performance for the WiNGS system by preventing unnecessary retransmission and reordering.