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Www.eng.monash.edu Gateway Multipoint Relays an MPR-based Broadcast Algorithm For Ad Hoc Networks Ou Liang, Ahmet Sekercioglu and Nallasamy Mani Department.

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Presentation on theme: "Www.eng.monash.edu Gateway Multipoint Relays an MPR-based Broadcast Algorithm For Ad Hoc Networks Ou Liang, Ahmet Sekercioglu and Nallasamy Mani Department."— Presentation transcript:

1 Gateway Multipoint Relays an MPR-based Broadcast Algorithm For Ad Hoc Networks Ou Liang, Ahmet Sekercioglu and Nallasamy Mani Department of Electrical and Computer Systems Engineering Monash University, Australia

2 2 Sections 1.Broadcasting in wireless ad hoc networks. 2.Multipoint Relays (MPRs). 3.Our new algorithm. 4.Conclusion and future work.

3 3 Broadcasting in wireless ad hoc networks Section 1Section 2Section 3Section 4 1.It is commonly used in routing protocols. 2.As a necessary mechanism in various applications that need to maintain global network information (paging a particular host or sending alarm signals).

4 4 Network wide broadcast in ad hoc networks Due to the limitation of radio power, a mobile node may not be within the transmission range of all other nodes. Therefore, broadcast packets have to be relayed by other recipient nodes. S Section 1Section 2Section 3Section 4

5 5 Proposed broadcast algorithms Generally, broadcast algorithms in ad hoc networks can be categorized into five groups [1] : Probability based algorithms. Distance based algorithms. Location based algorithms. Neighbor-designating algorithms. Cluster based algorithms. Section 1Section 2Section 3Section 4

6 6 Neighbor–designating algorithms 1.Each node informs neighbor nodes about its node information such as node IDs of neighbor nodes. Section 1Section 2Section 3Section 4 2.A node determines whether its neighbors should forward broadcast packets.

7 7 Neighbor–designating example S A C B Node S chooses its neighbors A, B and C to relay broadcast packets. Section 1Section 2Section 3Section 4

8 8 Cluster based algorithms 1.Network is clustered and cluster-heads are elected. Cluster-heads are referred to as dominators. 2.Cluster-heads select some connectors to connect other cluster-heads. Section 1Section 2Section 3Section 4

9 9 Cluster example 1 A B 2 C Dominators: {A, B, C} Connectors: {1, 2} Section 1Section 2Section 3Section 4

10 10 Multipoint Relays (MPRs) Section 1Section 2Section 3Section 4 It is a broadcast mechanism used in the Optimized Link State Routing protocol (OLSR) [2, 3], and it belongs to the family of neighbor–designating algorithms. Each node selects a subset of nodes from its one-hop neighbors to cover all its two-hop neighbors.

11 11 Multipoint Relays example Section 1Section 2Section 3Section 4 d b f a c e a {1, 2, 3} b {3, 4, 5} e {6, 7, 8} f {8} c { } d { } e {6, 7, 8} b {4, 5} f {8} c { } d { } b {4, 5} f { } c { } d { } Selected MPRs: {a, b, e}

12 12 Our Gateway Multipoint Relays (GMPR) Section 1Section 2Section 3Section 4 Node states Dominator: It is the cluster-head, and it performs MPR calculation. Dominatee: The nodes connected by dominators. Connector: Can only be entered from dominatee state. Candidate: Initial state that attends dominator election. 1.It is a combination of Clustering and Multipoint Relay methods. 2.Each node in the network can be in one of the four states: dominator, dominatee, connector and candidate.

13 13 Operations of GMPR Section 1Section 2Section 3Section 4 1.Dominators (nodes that covers most number of candidates) are elected in the network where all nodes can be covered by the dominators. 2.Each dominator selects MPRs to cover its two-hop neighbor nodes. 3.An MPR is a connector if it is selected by the largest dominator of this MPR. Only dominators and connectors forward broadcast packets.

14 14 Gateway Multipoint Relays example Section 1Section 2Section 3Section 4 DB F A E C G H I J O P N L K M 1.Elect dominators based on the candidate coverage. 2.Dominators calculate MPRs to cover two-hop neighbor nodes. 3.Each MPR decides whether it is the connector. Selected by H Selected by D Selected by H Selected by P Selected by D T

15 15 Self-pruning procedure Section 1Section 2Section 3Section 4 Aim: To further reduce retransmissions by preventing leaf-dominators forwarding broadcast packets. A dominator D is a leaf-dominator if it has a one-hop connector that can cover all Ds one-hop neighbors. A leaf-dominator is referred to as the Silent-dominator, which still selects MPRs but does not retransmit broadcast packets.

16 16 Self-pruning procedure example Section 1Section 2Section 3Section 4 G A D EHF I B C After selecting connectors Dominators: E, H Connector: F Then Both dominators apply self-pruning procedure, and H becomes a silent-dominator.

17 17 Simulation studies Section 1Section 2Section 3Section 4 SimulatorOMNeT++ with Mobility Framework. MAC protocolAssume a perfect MAC layer (error and collision free). Network area100m x 100m two dimensional area. Topology generating Randomly distribute nodes in the area. Each node is placed within the transmission range of a previously placed node to make sure connectivity. Number of nodes Range from 20 to 100. Transmission range Two transmission ranges: 25m and 50m. Number of runsA sufficient number of runs are conducted to achieve 95% confidence interval within a ±5% margin.

18 18 Simulation results Section 1Section 2Section 3Section 4 Transmission range R = 25m

19 19 Simulation results Section 1Section 2Section 3Section 4 Transmission range R = 50m

20 20 Conclusion and future work We have proposed a new efficient broadcast algorithm based on the Multipoint Relays and clustering methods. Simulation studies show that compared with related work, our algorithm generates fewer forwarding nodes thus reducing retransmissions and collisions. Future work: investigate the performance of our algorithm in both dense and mobile environment. Section 1Section 2Section 3Section 4

21 21 References [1]. J. Wu and F. Dai, A generic distributed broadcast scheme in ad hoc wireless networks, in Proceedings of MOBIHOC, 2002, pp [2]. A. Laouiti, A. Qayyum, and L. Viennot, Multipoint relaying: an efficient technique for flooding in mobile wireless networks, in 35th Annual Hawaii International Conference on System Sciences HICSS2001. [3].T. Clausen and P. Jacquet, Optimized link state routing protocol (OLSR), RFC 3626, Oct [online]. Available:

22 22 Questions?

23 23 Thank you!

24 24 Probability based algorithms It is similar to the blind flooding, but each node rebroadcast a packet with a predetermined probability value P. Problems: Can not guarantee full coverage in the network. Has little effect on in sparse network. Section 1Section 2Section 3Section 4

25 25 Distance based algorithms A node retransmit a broadcast packet if the distance between it and the sender of the packet is larger than a predefined threshold distance. S A B d1d1 d2d2 Problems: Energy wastage (unnecessary broadcast) Cannot guarantee full coverage Section 1Section 2Section 3Section 4

26 26 Location based algorithms Use positioning devices such as GPS (Global Positioning System) to provide precise locations of hosts in a network. S A B d1d1 d2d2 Additional coverage A host retransmits a broadcast packet if the additional area it covers is larger than a threshold value. Section 1Section 2Section 3Section 4


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