In multihop wireless networks, hop-by-hop reliability is generally achieved through positive acknowledgments at the MAC layer.However, positive acknowledgments introduce significant energy inefficiencies on battery-constrained devices.This inefficiency becomes particularly significant on high error rate channels.
We click here propose to reduce the energy consumption during retransmissions using a novel protocol that localizes bit-errors at the MAC layer.The proposed protocol, referred to as Selective Retransmission using Virtual Fragmentation (SRVF), requires simple modifications to the positive-ACK-based reliability mechanism but provides substantial improvements in energy efficiency.The main premise of the protocol is to localize bit-errors by performing partial checksums on disjoint parts or virtual 30x24x24 wall cabinet fragments of a packet.
In case of error, only the corrupted virtual fragments are retransmitted.We develop stochastic models of the Simple Positive-ACK-based reliability, the previously-proposed Packet Length Optimization (PLO) protocol, and the SRVF protocol operating over an arbitrary-order Markov wireless channel.Our analytical models show that SRVF provides significant theoretical improvements in energy efficiency over existing protocols.
We then use bit-error traces collected over different real networks to empirically compare the proposed and existing protocols.These experimental results further substantiate that SRVF provides considerably better energy efficiency than Simple Positive-ACK and Packet Length Optimization protocols.