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Energy-Efficient Communication Protocol for Wireless Microsensor Networks

Energy-Efficient Communication Protocol for Wireless Microsensor Networks. Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan. by Mikhail Nesterenko. Outline. I/O automaton definition examples of I/O automata execution operations on I/O automata composition hiding

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Energy-Efficient Communication Protocol for Wireless Microsensor Networks

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  1. Energy-Efficient Communication Protocol for Wireless Microsensor Networks Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan by Mikhail Nesterenko

  2. Outline • I/O automaton definition • examples of I/O automata • execution • operations on I/O automata • composition • hiding • fairness • properties and proof methods • invariants • trace properties • compositional reasoning • hierarchical proofs • complexity • randomization

  3. Radio and CommunicationModel • nodes have sensors and limited energy supply • nodes sense data and send it to centralized location – base station; base station has large energy supply • transmitter and receiver dissipate (use) the same amount of energy (50nJ/bit) • plus transmitter (amplifier) is using additional amount proportional to square of distance to transmit • radio channel is symmetric • constant bit rate data generation (every node is sensing and always ready to transmit)

  4. Energy Analysis of Routing Protocols • two models • direct communication to base station • drains the power of transmitters • since only base station receives no sensor’s energy is spent on the receivers • hence if base station is close to the nodes or energy to receive message is large, this strategy may be optimal • “minimum energy” multihop routing – in addition to sensing nodes act as routers to other nodes’ data • conventional protocol optimize transmitter’s energy minimum transmitter’s energy – MTE) but not receiver’s • see Figs. 3, 4, 5

  5. More Problems with MTE • MTE quickly drains the energy of nodes closest to base station (and they die) which, in turn, drains even more energy from nodes that are slightly off the base station – cascading effect • simulation • MTE – nodes closest to base station die first • direct – nodes furthest from bases station dies first • see Fig. 6

  6. Clustering • conventional clustering assumes that there is a cluster head (local base station) that collects the sensor data and transmits to base station • cluster head is close to the sensors so their energy is conserved • cluster head routes all messages from the cluster and quickly dies

  7. Low-Energy Adaptive Clustering Hierarchy (LEACH) • to conserve energy a cluster head LEACH includes randomized rotation of a cluster head • cluster head “compresses” (aggregates) the data before sending to base station • node randomly (proportional to the amount of remaining energy remaining) elects itself cluster head (independently of other nodes in the network) • informs neighbors about it • gives schedule as two when the neighbors send their data to cluster head • aggregates the sent data and sends it to base station • the number of clusters is determined in advance to conserve overall energy (see Figs 7, 8, 9, 10) • there exists an optimum number of cluster heads (~5%) • with this optimum LEACH reduces energy dissipation up to 7 times • less cluster heads, less detailed picture

  8. System Lifetime in LEACH • besides decreasing energy dissipation, LEACH increases system lifetime • under LEACH it takes approx 8 times longer for the first node to die and 3 times longer for the last node to die (compared to any other protocol) – see Table 1 • the pattern of nodes deaths is uniform which increases usability of the system as nodes dies; see Fig 12, compare to Fig 6

  9. LEACH Details • functioning is in rounds, each round has two phases • setup phase (short) – clusters are organized • steady phase (long) – data is transferred to the base station • phases • advertisement – each node probabilistically elects to be a cluster head and sends a “cluster-head-advertisement” message with the same energy, a non-head node picks the head on the basis of received signal strength • cluster setup – the nodes inform cluster heads about their choice • schedule creation – cluster head creates TDMA schedule and broadcasts it to the cluster • data transmission – each node sends data to cluster head, cluster head aggregates and forwards to base station • to reduce interference between clusters CDMA spreading codes are used (different frequencies?) • LEACH can be extended to hierarchy

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