1. © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto 1 Improving the Performance of IEEE802.11s Networks using Directional Antennas over Multi-Radio/Multi-Channel Implementation – The Research Challenges Doctoral Symposium on Informatics Engineering INESC PORTO-FEUP Rua Dr. Roberto Frias, 378 4200 - 465 Porto, Portugal Email: kandasamy@inescporto.pt

2. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 2 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Outline Introduction Rationale State of The Art Research Challenges Directional Antenna Model Conclusion

3. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 3 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Introduction Wireless Mesh Networks (WMNs) –dynamic setup –mobile/static nodes Omnidirectional Antenna (OA) –IEEE802.11 standard –saturation in larger network or denser scenario Directional Antenna (DA) – Rationale?

4. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 4 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Rationale Gain of Directional Antenna –multi small hop  single long hop transmissions –lower the transmission delay Interference Reduction Capability –avoid interference that comes from unwanted directions –increases the signal to noise ratio (SNR) Utilization of Network –Increased Capacity –More users utilizing the network.

5. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 5 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Rationale Figure 1 – Omnidirectional Antenna Figure 2 – Directional Antenna

6. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 6 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Rationale Figure 3 – Traditional Directional Antenna Figure 5 – Streerable Beam Antenna Figure 4 – Switched Beam Antenna

7. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 7 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto State of The Art Wireless Mesh Networks –Hop Count Metrics [6] –Load Balance Traffic [7] –Reduction End to End Capacity - interference[8] Directional Antenna and Directional MAC Protocols [10,11,15] –Sectoring 120Deg – capacity increase by 1.714 [9] –Directional MAC – throughput 2x better than 802.11 [11] –Multihop MAC – outperforms 802.11 but depends on topology [12] Protocol Name Antenna Type Carrier Sensing Virtual Sensing With ACK Backoff Algorithm Hidden Terminal Free Exposed Terminal Free Busy Tone Based Split Channel Basic Protocol 802.11OmniYesYes/NoYesBEBYes/NoNo - MAC/DA1DirYesYes/NoYesBEBYes/NoYesNo 802.11 MAC/DA2DirYesYes/NoNoBEBYes/NoNo/YesNo 802.11 MAC/DA2 ACKDirYesYes/NoYesBEBYes/NoNo/YesNo 802.11 DBTMAOmniNoYesNoMILDYes - DBTMA/DADirNoYesNoMILDYes DBTMA

8. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 8 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto State of The Art Multi-Radio/Multi-Channel Wireless Mesh Networks –Two Radios (NIC) - 70% Throughput Increase [16], 8 times network throughput Improvement [17] Multi-Radio/Multi-Channel MAC Protocols –Multichannel Carrier Sense Multiple Access (MCSMA) – uses Total Receive Signal Strength [18] –Interleaved Carrier Sense Multiple Access (ICSMA) – interleaving mechanism [19] Cross Layer Mechanisms –significant performance gain [14-15] –at cost of higher overhead Figure 6 – ICSMA

9. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 9 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Research Challenges Directional Antenna –IEEE802.11 - No gain with DA More technical challenges  hidden terminal, deafness –suitable MAC protocol needed to best utilize DA may also worsen communications in the direction of transmission. transmitted power  contained till destination power saving MAC critical in battery operated AP/UE e.g. Solar Powered WMN Cross Layer –impossible to design a universal routing/MAC/multicast/transport protocol  expect it function efficiently in all situations –self-adaptive to network dynamics  meet end-to-end real-time deadlines of the applications.

10. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 10 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Research Challenges Mobility –AP/UE will come into a mesh and disappears in random manner –Fast Admission/Removal - AP/UE, once discovered Routing –Best routing but also a fair routing - lesser number of hops –Reducing control signal overheads and congestion in the network  increasing throughput for good user experience. Multi-Radio/Multi-Channel Wireless Mesh Networks –Frequency and Channel Diversity – additional radio interfaces –Switching strategies – Cognitive Radio

11. Improving the Performance of IEEE802.11s NT using DA over Multi-Radio/Multi-Channel Implementation – The Research Challenges 11 © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto Conclusion DA, directional MAC protocols over Multi-Radio/Multi-Channel approaches  increasingly studied Research Challenges  Opportunity for future work –Hot research topic as presented in the state of the art section. –Research activities still growing due to the immense benefit Envisage an evolution towards improved wireless mesh networks performance utilizing directional antennas for both the UE and also the AP.

12. © Saravanan Kandasamy, Ricardo Morla, and Manuel Ricardo,INESC Porto 12 Questão?