Wireless Mesh Networks Presented by: Sulaiman Al-Sulaim, 200425040 Meshari Al-Obaid, 200429300

1. Wireless Mesh Networks Presented by: Sulaiman Al-Sulaim, 200425040 Meshari Al-Obaid, 200429300 References: 1.http://en.wikipedia.org/wiki/Wireless_mesh_networks 2.http://en.wikipedia.org/wiki/IEEE_802.11s 3.http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01509968 4.http://communication.howstuffworks.com/how-wireless-mesh-networks-work2.htm 5.http://www.pcmag.com/article2/0,2817,1130864,00.asp

2. WMNs • This presentation consists of -Overview -Layered Communication Protocols -Current &Future Application

3. Overview • Mesh radio nodes • Types of nodes: - Mesh routers mesh back bone, mesh routing functionality , gateway functionality - Mesh clients

4. Continue, Overview Figure-1 Survey on Wireless Mesh Network [3] http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01509968

5. Physical layer • adaptive error resilience through link adaptation modulation, coding rates • For high-data rate: - OFDMA - UWB • To avoid wireless impairment: - Antenna diversity - MIMO

6. Continue, Physical layer • spectrum utilization - Frequency-agile radios - Cognitive radios

7. MAC layer • Two possible designs: 1)- Single channel MAC approaches: - Modifying existing MAC protocols Adjust parameters of CSMA/CA -Cross-layer design: Directional antenna-based MACs MACs with power control - Innovative MAC protocols TDMA or CDMA MAC protocols )complexity, cost, compatibility with existing MACs)

8. Continue, MAC layer 2)- Multi-channel MAC approaches - Multi-channel single-transceiver MAC for cost & compatibility. - Multi-channel multi-transceiver MAC one MAC. - Multi-Radio MAC multi MAC & PHY. multi-radio unification protocol(MUP)

9. Routing Layer For a routing protocol to be optimum, it must be: • Scalable. • Robust. • efficient routing with mesh infrastructure. • has multiple performance metrics. Routing Protocols with various performance metrics: • Three link quality metrics are used by LQSR; ETX, RTT and per-hop packet pair. • ETX achieves the best performance in the stationary nodes. • The minimum hop-count metric surpasses all three metrics in mobile nodes.

10. Multi Radio Routing: • Solves the previous issue of the mobile nodes. • New performance metric called (WCETT) is introduced. • WCETT combines both link quality metrics and minimum hop-count. • Good trade off between delay and throughput. Multi Path Routing: • achieves better load balance and high fault tolerance. • End-to-end delays, throughput and fault tolerance can be improved. • multiple paths backup each other if one of them is down. • Complexity.

11. Figure-2 Multi path in WMNs [1] http://en.wikipedia.org/wiki/Wireless_mesh_networks

12. Geographic Routing: • Topology change has less impact. • using the nodes location information and the destination node. • planner graph based geographic routing algorithms are used to guarantee the delivery.

13. Transport Layer there are no dedicated transport protocols for wireless mesh networks. There exist many transport protocols for ad hoc networks. Reliable transport protocols can be divided to two types: • TCP variants. • New transport protocols. TCP variants is better than the classical TCPs by considering the following aspects: Non Congestion Packet Losses: • In the classical TCP unnecessary congestion avoidance occurs. • a fast drop in the network throughput happens, when non-congestion losses occur.

14. Unknown Link Failure: • occurs due to the mobility of the nodes. • the single point of failure is avoided in WMNs. • Possibility of having a link failure in WMNs. • detection of the link failure will help in improving TCP performance. Network Asymmetry: • differences between the transmit and receive paths. • the difference in transmit and receive bandwidth. • the imbalance in the loss rate. • ACKs are affected due to asymmetry, TCP performance will be dramatically degraded. • ACK filters and ACK congestion control reduces networkasymmetry.

15. Large RTT Variations: • occur due to the frequent change of routing paths. • reduces the TCP performance. • New Transport protocol called ATP is developed for ad hoc networks. • ATP: • Rate based transmission. • Quick start during connection initiation. • Work supported congestion detection and control. • No transmission timeout. • Decoupled congestion control and reliability.

16. Current Applications In the Lack of Infrastructures: • Best solution for Countries that don’t have wired infrastructure. • can serve a whole village by connecting its nodes to one cellular or satellite internet connection. • Suitable for remote and hard-to-reach areas. Education: • Many education institutes are changing their networks to wireless mesh networks. • it can serve a large number of users. • the ease of installation. • capability of handling high bandwidth needs.

17. Figure 3 Ease of installation [4] http://communication.howstuffworks.com/how-wireless-mesh-networks-work.htm

18. Future Implementations Automobiles with built-in WMNs Nodes: • Drivers can form a wireless mesh network while they are driving. • Can share each other's music collection or other audio content. Military Purposes: • Sensor-chips occupied with wireless mesh nodes dropped on the battlefield. • Provide certain information like GPS coordinates and alerts. • these chips can communicate with each other.

19. Thank You Feel Free To Ask Any Question ?