An ARQ and HARQ interaction mechanism for IEEE 802.16j system

IEEE 802.16j is a promising option in future mobile communication. Using both ARQ (Automatic Repeat reQuest) and HARQ (Hybrid ARQ) in the 802.16j system can provide more reliable data transmission, while some issues, especially the long end-to-end latency due to multi-hop transmission, need to be considered. In this paper, we propose a simple but effective ARQ and HARQ interaction mechanism. In the mechanism, the ARQ_RETRY_TIMEOUT value dynamically changes according to the messages obtained from HARQ process. When the value is set to zero, a fast ARQ retransmission can be triggered. When the value is raised, it ensures that HARQ retransmission operation of an ARQ block can be completed before ARQ retransmission of the block occurs. The performance analysis results show that employing the proposed mechanism in 802.16j system using both ARQ and HARQ on a single connection can reduce the average transmission delay and delay jitter of an ARQ block.