In IEEE 802.16 specifications, a CRC field can be attached in the rear of a WiMAX MPDU. Thus, each intermediate node (relay node or base station) in an 802.16-based multihop network can perform error detection on a received WiMAX MPDU. On the sender, the ARQ mechanism will be enabled to retransmit the MPDU if a transmission error occurs and an ACK message cannot be received. However, the ARQ mechanism is unsuitable for real-time traffic due to the delay consideration and the CRC field becomes an option to reduce the overhead of a WiMAX MPDU. Once the CRC field is removed from a WiMAX MPDU, the error occurrence cannot be detected by the intermediate nodes in time, and the erroneous data is still forwarded in the network but discarded by the destination. The resources of nodes in a network are wasted. Hence, the error detection mechanism should be retained for real-time traffic, but the overhead of CRC should be reduced. In this paper, we study an efficient discrete-error-checking scheme (DECS) to reduce the CRC overhead for real-time traffic. The DECS only needs several CRC checking bits, which are attached behind some WiMAX MPDUs. The DECS can efficiently provide the error detection for the intermediate nodes to discard these erroneous and useless data early. Thus, the utilization of node resources and wireless bandwidth can be improved significantly
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