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Advisor : Prof. Yu- Chee Tseng Student : Yi-Chen Lu

Advisor : Prof. Yu- Chee Tseng Student : Yi-Chen Lu. ELPA: A Multicast Routing Protocol Using Energy Efficient and Load Balancing Probabilistic Anycast. Outline. Introduction Related Work Motivation Goal ELPA Simulation Conclusion. Outline. Introduction Related Work Motivation

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Advisor : Prof. Yu- Chee Tseng Student : Yi-Chen Lu

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  1. Advisor : Prof. Yu-Chee Tseng Student : Yi-Chen Lu ELPA: A Multicast Routing Protocol Using EnergyEfficient and Load Balancing Probabilistic Anycast

  2. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

  3. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

  4. Introduction • A WSN is composed of numerous inexpensive wireless sensor nodes, each of which is normally powered by batteries • Wireless sensor nodes are capable of not only collecting, storing, processing environmental information, but also communicating with neighboring nodes • Many research works have been dedicated to WSNs, such as routing, self-organization, deployment, and localization

  5. Introduction • Multicast is a fundamental routing service of network communication • In WSN, a single message can be delivered to multiple destinations efficiently through multicast communication • Many applications of multicast have been developed such as appliance automation, health care, and environmental security and control

  6. Introduction • ZigBee, , which is characterized as low-rate, short-range, low-cost, and easy-deployment, is a standard defined by ZigBee Alliance especially for WSN • In ZigBee, multicast communication is implemented by regional flooding • Although ZigBee multicast is simple and has low memory cost, it has several significant drawbacks • Heavy traffic overhead • High energy cost • Unreliable

  7. Outline • Introduction • Related Work • ZigBee Multicast • Overlay Multicast • Geographic Multicast • Relay-Selection Multicast • Motivation • Goal • ELPA • Simulation • Conclusion

  8. ZigBee Multicast • In ZigBee, multicast members are physically separated by a hop distance of no more than MaxNonMemberRadius • Depending on whether the source node is a group member or not, ZigBee multicast is divided into two modes • Member mode • Non-member mode

  9. ZigBee Multicast • Member mode • Exploit regional flooding to deliver the multicast message • Non-member mode • Perform a route discovery procedure to find a nearby member node • Unicast the message to the member node • Switch to member mode

  10. ZigBee Multicast Illustration • Member mode • Non-member mode Region bounded by MaxNonMemberRadius • Drawbacks of ZigBee multicast • Heavy traffic overhead • High energy cost • Unreliable Member Region bounded by MaxNonMemberRadius Non-Member Member Route Discovery

  11. Related Work • Overlay multicast • PAST-DM • Member nodes have to replicate the packets which leads to excessive energy consumption and redundant transmissions • AOM • Packet header overhead • Tree maintenance overhead • Overlay multicast only consider the network topology maintenance issues

  12. Related Work • Geographic multicast • GMREE • Cost over progress ratio • Packet header overhead • HGMR • HRPM + GMR • Drawbacks • Impractical assumption that location information is available • Suffering from the face routing cost • High computing complexity

  13. Related Work • Relay-selection multicast • uCast • Too simple • Steiner-tree-based multicast • MIP • Each node has to dynamically adjust transmission power • NJT and TJT • High computing complexity • These three kinds of multicast approaches lead to single node failure problem because the multicast paths are fixed

  14. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

  15. Motivation • As a result of the limited power resource, energy efficient multicast is a critical issue in WSN • Many approaches have been proposed to study on the energy-efficient multicast issues in WSN • In ZigBee, the multicast communication is not only energy inefficient but also unreliable • Other proposed approaches either have significant drawbacks or are not compatible with ZigBee

  16. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

  17. Goal • Propose a multicast routing protocol which has the following features • ZigBee Compatible • Energy efficient • Less energy consumption • Load balancing • Prolong the network lifetime • Avoid single node failure problem • Reliable • Higher delivery ratio

  18. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Network Formation • Multicasting • Simulation • Conclusion

  19. ELPA – Network Formation • In Network Formation phase, each member node disseminates necessary information to the sub-network limited by a hop distance of MaxNonMemberRadius, which is defined in ZigBee specification • Each node maintains a Multicast Information Table (MIT), which keeps the information of only the members located within the region bounded by MaxNonMemberRadius hops

  20. ELPA – MIT Maintenance • Each node periodically broadcasts a HELLO packet • Carry the node’s residual energy Er in the packet • Carry the number of reachable member nodes Ng in the packet • Each node maintains the max number of reachable member nodes among all nodes in the network, noted as Ngmax

  21. ELPA – MIT Maintenance • When a node i receives a HELLO packet • Remember the residual energy if the HELLO packet comes from node i’s neighbor • Compare Ng with Ngmax maintained by node i • If Ng in the packet is smaller, replace Ng with Ngmax • Else, replace Ngmax with Ng • If the HELLO packet is originated from a member node and node i is adjacent to the member node within MaxNonMemberRadiushops • Remember the hop distance to the member node and rebroadcast • If the HELLO packet is not originated from a member node • Node i does not rebroadcast

  22. ELPA – Network Formation • Multicast Information Table (MIT) • Through the dissemination of HELLO packets, each node builds their own MITs • MIT keeps the information of only the members located within the region bounded by MaxNonMemberRadius hops

  23. ELPA-MIT Maintenance Example HELLO HELLO HELLO HELLO HELLO HELLO Region bounded by MaxNonMemberRadius

  24. ELPA-MIT Maintenance Example

  25. ELPA - Multicasting • In Multicasting phase, ELPA adopts a probabilistic anycast mechanism to realize the multicast protocol • The probabilistic anycast is based on a coverage over cost ratio • The goal of the coverage over cost ratio is to maximize the number of reachable member nodes while minimize the energy consumption

  26. ELPA – Initiating A Multicast • When a node wants to initiate a multicast, it piggybacks the following information in the packet and then broadcast the packet • The destination set D = {d1, d2,…, dn}, where diis the address of a member node i that is reachable by the source node • The distance set H = {h1, h2,…, hn}, where hiis the hop distance to di • Average residual energy of the source node’s neighbors, noted as En

  27. ELPA – Initiating A Multicast • When a node wants to initiate a multicast, it piggybacks the following information in the packet and then broadcast the packet • The destination set D = {d1, d2,…, dn}, where diis the address of a member node i that is reachable by the source node • The distance set H = {h1, h2,…, hn}, where hiis the hop distance to di • Average residual energy of the source node’s neighbors, noted as En

  28. ELPA – Upon Receipt of A Multicast Packet • A node which receives a multicast packet is called a candidate relay • The candidate relay compares its own destination set and distance set with those in the packet • For each destination member which exists in both destination sets, if the hop distance maintained by the candidate relay is longer than that in the packet • Remove the member from the candidate relay’s destination set • After the comparison • If the candidate relay’s destination set is not empty, it generates a random back-off interval based on the coverage over cost ratio • Otherwise, the packet is not rebroadcast

  29. ELPA – Coverage Over Cost Ratio • Coverage Over Cost Ratio • The coverage over cost ratio is targeted at reaching as many member nodes as possible while consuming as little energy as possible

  30. ELPA – Radom Back-Off Timer • The back-off timer interval t is generated randomly within the range [0, T] • With greater f value and greater residual energy Er, T should be smaller • Therefore, a node which is more energetic and covers more destination members with less energy cost has a better chance to generate a shorter back-off interval

  31. ELPA – Packet Forwarding • A candidate relay takes the following steps when it receives a multicast packet • Compare the destination sets, the packet is not forwarded if the candidate relay’s destination set is empty after the comparison • Calculate T by applying Eq.(2), and generate a random back-off timer interval t within [0, T] • If the same multicast packet is overheard from other candidate relays before the timer expires, go to step 4. Otherwise, go to step 5

  32. ELPA – Packet Forwarding • Compare the destination set in the overheard packet with the candidate relay’s destination set, remove the members which exist in both sets from the candidate relay’s destination set • When the timer expires • If the candidate relay’s destination set is not empty, replace the destination set, distance set, and En in the packet by those sets of the candidate relay • On the other hand, if the candidate relay’s destination set is empty, it will not forward the multicast packet

  33. ELPA – ACK Mechanism • After sending out the multicast packet, the sender waits for a period of time twaitto confirm that all the member nodes in the destination set are covered by the relay nodes • The source node makes such confirmation by overhearing the packets from the relay nodes • Every member which is covered by the relay nodes will be removed from the sender’s destination set • The sender decides whether to retransmit the packet or not according to whether the destination set is empty after twait expires

  34. ELPA – Packet Forwarding Example Multicast D={8} H={1} No Back-Off No Back-Off No forward Multicast D={5, 8} H={2, 2} Multicast D={8, 15} H={2, 1} Multicast D={15} H={2} No Back-Off Multicast D={15, 21} H={1, 1} Multicast D={21} H={2} Multicast D={8} H={2} No Back-Off No Back-Off Multicast D={5} H={2} No Back-Off Multicast D={5} H={1} No Back-Off

  35. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

  36. Outline • Introduction • Related Work • Motivation • Goal • ELPA • Simulation • Conclusion

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