cross layer design in wireless mesh networks

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Cross Layer Design in Wireless Mesh Networks

指導教授：吳和庭教授報告：江昀庭2012/5/8

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Source Reference[1] N.M. Salleh, M. Muhammad, M. S. Zakaria, V.R. Gannapathy, M.K.

Suaidi, I. M.Ibrahim, M. Z. A. AbdulAziz, M.S. Johar, M.R. Ahmad “Wireless mesh network - Cross layer design challenge!!” Applied Electromagnetics, 2007. APACE 2007. Asia-Pacific Conference on Digital Object Identifier: 10.1109/APACE.2007.4603957

Publication Year: 2007 , Page(s): 1 - 10[2] Arianpoo, N.; Jokar, P.; Leung, V.C.M. “Enhancing TCP

Performance in Wireless Mesh Networks by Cross Layer Design” Computing, Networking and Communications (ICNC), 2012 International Conference on Digital Object Identifier: 10.1109/ICCNC.2012.6167405

Publication Year: 2012 , Page(s): 177 - 181

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Outline Introduction Cross Layer Design

Purpose Approach Challenge

Fair End-to-end Bandwidth Allocation(FEBA) More Hops Higher Priority (MHHP) Analytical Justification Performance Evaluation Conclusion

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Introduction Cross layer networking in the physical layer,

network layer and transport layer. Enhancing TCP performance by Cross Layer

Design. (MHHP)

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Purpose Improve bit error rate and noise between

neighbor in WMNs.

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Approach (1) Can be performed in two ways:

The first approach is to improve the performance of a protocol layer by taking into account parameters in other protocol layers. Typically, parameters in the lower protocol layers are reported to higher layers.

The second approach of is to merge several protocols into one component.

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Approach (2)

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Challenge (1) Physical Layer

• It’s not fundamentally different from other wireless technologies.

Network Layer• the wireless link where WMNs are radically

different from 3G systems, WLANs and WMANs. All these technologies use a single wireless link and hence have no need for a network layer.

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Challenge (2) Transport Layer

• Transport protocol is used TCP on the Internet. Unfortunately, TCP was designed and fine-tuned for wired networks where most packet losses are due to buffer overflows in the routers.

• Bit-error rate in wireless• Move and Work off

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• Fair End-to-end Bandwidth Allocation(FEBA) More Hops Higher Priority (MHHP) Analytical Justification Performance Evaluation Conclusion

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Fair End-to-end Bandwidth Allocation

FEBA bandwidth allocation is based on the weight of each flow.

FEBA assigns larger bandwidth to the nodes that relay a larger number of flows.

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• Fair End-to-end Bandwidth Allocation(FEBA) More Hops Higher Priority (MHHP) Analytical Justification Performance Evaluation Conclusion

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More Hops Higher Priority (1) To solve the unfairness problem of the nodes

with a larger number of hops. Propose an algorithm that gives a higher

priority to the flows coming from the farther nodes.

FlowPriority = PacketPriority × DistancetoDestination (1)

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More Hops Higher Priority (2) Giving priority to the nodes based on the

number of traversed hops might increase the computational load; but that is not an issue in WMN.

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More Hops Higher Priority (3) It’s an example. Assume same priority for all flows.

Throughput increase 115%

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• Fair End-to-end Bandwidth Allocation(FEBA)• More Hops Higher Priority (MHHP) Analytical Justification Performance Evaluation Conclusion

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Analytical Justification (1)

X is the transmit rate in bytes per second s is packet size in bytes RTT is the Round Trip Time p is the loss event rate, RTO is the TCP retransmission time out value in seconds b is the number of packets acknowledged by a single TCP

ACK packet.

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Analytical Justification (2) This method is in favore of the nodes with

larger number of hops; MHHP decreases RTT of farther nodes and increases RTT of closer nodes. Balancing RTT helps to make balance the throughput in the network.

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Performance Evaluation (1)

Fig. 2. End to end throughput of the longest flow

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Fig. 3. Round Trip Time of the longest flow

Decreases RTT of farther nodes and increases RTT of closer nodes ?

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Fig. 4. End to end throughput of the shortest flow

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Fig. 5. Round Trip Time of the shortest flow

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Fig. 6. End to end throughput of the longest flow - ring topology

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Fig. 7. End to end throughput of the longest flow - star topology

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Fig. 8. End to end throughput of the longest flow - triangular topology

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Fig. 9. Round Trip Time of the longest flow - ring topology

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Fig. 10. Round Trip Time of the longest flow - star topology

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Conclusion (1) Cross Layer Design improve bit error rate and

noise between neighbor in WMNs. In order to improve protocol efficiency, cross

layer design becomes indispensable. Cross-layer design have risks due to loss of

protocol layer abstraction

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Conclusion (2)

The impact of using MHHP on throughput in WMN is significant, especially when the number of hops is less than 5.

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Q&A

Thanks for your listening

cross layer design in wireless mesh networks

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