CuMPE : CLUSTER-MANAGEMENT AND POWER EFFICIENT PROTOCOL FOR WIRELESS SENSOR NETWORKS ITRE’05 Information Technology: Research and Education Shen Ben Ho and Xiao Su Department of Computer Engineering, San Jose State University, San Jose, CA 95192

Outline Introduction Related work CuMPE Protocol ROUTING IN CuMPE MAC SCHEDULING IN CuMPE Simulation Conclusions

Introduction – background Important issues in data gathering Low power consumption Limited power supply Low transmission delay Large number of sensor nodes

Introduction – motivation Routing and MAC protocols should be power efficient Should organize nodes in a way that the Message transmission delay is small

Related work - HIT Hybrid Indirect Transmissions (HIT) for Data Gathering in Wireless Micro Sensor Networks with Biomedical Applications (CCW 2003 )

Related work - HIT Closest node to i d(u, H) < d(i, H) d(i, u) < d(i, H). Parallel transmissions The drawback distance advertisement messages cover the entire cluster

CuMPE - overview Cluster head election Route set-up TDMA scheduling Data transfer

ROUTING IN CuMPE Cluster head election Route set-up find routing trees with minimum transmission cost reduce the energy used

Cluster head election Depending on requirements from application Four ways can be used to select cluster head: Random Node ID Residential energy Connectivity or geography location

Route set-up Finds the path to the cluster head with minimum cost Phase one: Cluster Head Advertisement Phase two: Path setup

Cluster Head Advertisement Advertisement (fixed signal strength) Type: DISCOVERY Cost: 0 Any node receiving this packet knows the ID of cluster head the signal strength of the packet. CH a db f h g e c

Path setup Updated message (fixed signal strength) Type: DISCOVERY Cost: (cost to cluster head) Any node receiving the updated information packet knows node ID of the sender (probably upstream node) cost from the sender to the cluster head cost to the sender. CH a db f h g e c

Path setup The node receives update message The New cost Compares current cost High : ignore Low : the sender become the new upstream node CH a db f h g e c Cost(c,b)+Cost(b,CH) <Cost(c,CH) Cost(d,b)+Cost(b,CH) >Cost(d,CH)

Path setup CH a db f h g e c

MAC SCHEDULING IN CuMPE Use TDMA to schedule nodes for transmission Reduce overall delays of message transmission Blocking Nodes Critical Path

Blocking Nodes G blocks nodes H to L Node X block node Y : d( X, uX) > d( X, uY)

Critical Path Critical path : the path that involves the longest delay to transmit messages from leaf nodes to the root. the delay depends on the height of the path the number of downstream nodes along the path.

TDMA scheduling There are four phases in this step Upstream node notice Sending downstream node list and downstream-blocking node list Schedule setup Schedule broadcast

Upstream Node Notice The message Type: UpStream Upstream: ID of the upstream neighbor Any node that hears this message will put the sender downstream node list (its own ID) downstream-blocking node list. A C D B F H G E Downstream node list: D Downstream node list: H G Downstream-blocking node list :D

Sending Downstream Node List and Downstream-Blocking Node List A C D B F H G E

Schedule setup The protocol assigns the time slot reversely i.e., assigns the last time slot first The protocol checks if any blocking node is assigned to that time slot. A C B

Schedule setup Nodes with an asterisk on right are in the queue. C BB E F

Schedule setup Node D blocks the downstream nodes of C and E (i.e., nodes E, F, G, and H), The algorithm shifts node F to the next free slot B E F F E F D

Schedule setup Choose to delay the blocked node results in a shorter overall delay Slot 1Slot 2Slot 3Slot 4Slot 5Slot 6Slot7 BA HIJKL GCDEF Slot 1Slot 2Slot 3Slot 4Slot 5Slot 6Slot7Slot8Slot9Slot10Slot11 BA HIJKL GCDEF

Schedule setup Finished TDMA scheduling all the nodes in the queue are leaf nodes have no downstream nodes E F D F D G H G

Schedule Broadcast The cluster head sends the TDMA schedule information to the cluster members. The message has the following fields Type: Timeslot Time slot: the time slot assigned. A C D B F H G E

Simulation Network: diameter of 1000 meters 100 nodes Cluster heads : 5% node Initial energy of node : 25 joules Packet size :100 bits The route is recomputed every 100 rounds of data gathering

Simulation- Lifetime

Simulation- Average Delay

Conclusion CuMPE consists of a routing and a TDMA scheduling algorithm has longer life time has shorter transmission delay