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Unformatted text preview: ain translates to convolution in the spectral domain. Thus the resulting signal is wideband - Frequency Hopping (FH): carrier frequency rapidly hops among a large set of possible frequencies according to some pseudo random sequence (the code). The set of frequencies spans a large bandwidth. Thus the bandwidth of the transmitted signal appears as largely spread An Energy-Efficient MAC Protocol for Wireless Sensor Networks (S-MAC) [Ye+ 2002] S- MAC protocol designed specifically for sensor networks to reduce energy consumption while achieving good scalability and collision avoidance by utilizing a combined scheduling and contention scheme The major sources of energy waste are: 1. 2. 3. 4. collision overhearing control packet overhead idle listening S-MAC reduce the waste of energy from all the sources mentioned in exchange of some reduction in both per-hop fairness and latency (S-MAC) [Ye+ 2002] S- MAC protocol consist of three major components: 1. 2. 3. periodic listen and sleep collision and overhearing avoidance Message passing Contributions of S-MAC are: The scheme of periodic listen and sleep helps in reducing energy consumption by avoiding idle listening. The use of synchronization to form virtual clusters of nodes on the same sleep schedule In-channel signaling puts each node to sleep when its neighbor is transmitting to another node (solves the overhearing problem and does not require additional channel) Message passing technique to reduce application-perceived latency and control overhead (per-node fragment level fairness is reduced) Evaluating an implementation of S-MAC over sensor-net specific hardware A Transmission Control Scheme for Media Access in Sensor Networks [Woo+, 2003] Why STUDY MAC protocols in sensor networks? Application behavior in sensor networks leads t...
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- Spring '08