CPR: A CRC-based packet recovery mechanism for wireless networks

In wireless networks, the cyclic redundancy check (CRC) technique often cooperates with retransmission schemes to achieve reliable transmission. However, too many retransmissions in error-prone wireless environments not only create potential latency but also limit the overall bandwidth capacity. In general, an erroneously received packet is likely to possess some useful information, by which receivers can derive the original packet from a number of erroneously received copies. This study proposes a CRC-based packet recovery (CPR) mechanism to determine the original packet by minimizing the number of retries per packet. The CPR mechanism only buffers the first erroneously received copy and maintains a bitmap vector to relax the buffer requirement to derive the positions of inconsistent bits from erroneous copies. Based on these bit positions, the CPR mechanism generates all candidate packets, one of which is likely to be the correct packet. This study also designs two architectures with different numbers of CRC encoders to implement the proposed CPR mechanism for evaluations and comparisons. Performance evaluation results confirm that the proposed CPR mechanism can significantly reduce unnecessary retransmissions and buffer space consumption, compared with the existing mechanisms. Results also show that different architectures reveal a tradeoff between hardware cost and processing delay.