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Báo cáo hóa học: "Research Article An Energy-Efficient Link Layer Protocol for Reliable Transmission over Wireless Networks"

Research Article An Energy-Efficient Link Layer Protocol for Reliable Transmission over Wireless Networks | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID791201 10 pages doi 10.1155 2009 791201 Research Article An Energy-Efficient Link Layer Protocol for Reliable Transmission over Wireless Networks Adnan Iqbal and Syed Ali Khayam School of Electrical Engineering and Computer Sciences National University of Sciences and Technology NUST 44000 Islamabad Pakistan Correspondence should be addressed to Adnan Iqbal adnan.iqbal@seecs.edu.pk Received 20 January 2009 Accepted 28 July 2009 Recommended by Lawrence Yeung 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 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 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 biterror traces collected over different real networks to empirically compare the proposed and existing protocols. These experimental results further substantiate that