1. Sebastian Max Radio and Frequency Assignment in Multi-Radio Multi-Channel Wireless Mesh Networks Radio and Frequency Assignment in Multi-Radio Multi-Channel Wireless Mesh Networks Sebastian Max Department of Communication Networks Faculty 6, RWTH Aachen University, Germany

2. Sebastian Max 2Overview Usage scenario Wireless mesh network types Multi-Radio Multi-Channel (MRMC) radio-to-link assignment –Problem –Optimization algorithm –Evaluation Summary & conclusion

3. Sebastian Max 3 Usage Scenario: Public Internet Access 1km 2 Service Area –Few km² –Densely built-up area No line-of-sight conditions –High user density Radio access technology –IEEE 802.11 WLAN –License-exempt frequency bands Deployment example –Mountain View, California © http://wifi.google.com/city/mv/apmap.html, 10.03.2009

4. Sebastian Max 4 Classic Wireless LAN

5. Sebastian Max 5 Classic Wireless LAN with Infrastructure

6. Sebastian Max 6 Wireless Mesh Network

7. Sebastian Max 7 Dual-Radio Wireless Mesh Network

8. Sebastian Max 8 Multi-Radio Multi-Channel (MRMC) Wireless Mesh Network

9. Sebastian Max 9 Multi-Radio Multi-Channel (MRMC) Wireless Mesh Network

10. Sebastian Max 10 Multi-Radio Multi-Channel (MRMC) Radio/Link Assignment Maximize network throughput Constraints –Maximum number of radios –Maximum number of channels Complete network Per node –Connectivity Assumptions –Given traffic distribution

11. Sebastian Max 11 Multi-Radio Multi-Channel (MRMC) Radio-to-Link Assignment Algorithm Channel expansion –Neglect restricted number of channels –Iteratively Find network bottleneck Reduce load on bottleneck Until maximum number of radios is reached  Local search for optimal configuration Channel reduction Combine two least loaded channels Start with dual-radio network

12. Sebastian Max 12Evaluation One square km service area –30 Nodes: Mesh Points (MPs) + Access Points (APs) –64 Stations –25 different random scenarios –5, 10 & 15 MPs per AP  Varying route length, hidden/exposed nodes Saturation throughput –Lower bound: dual radio wireless mesh network –Upper bound: no MPs –MRMC configuration with 2, 3, 5, 10 channels 3 or 4 radios System spectral efficiency –Same configurations as in saturation throughput

13. Sebastian Max 13 Evaluation: Saturation Throughput

14. Sebastian Max 14 Evaluation: System Spectral Efficiency

15. Sebastian Max 15 Summary & Conclusion Radio/link assignment algorithm for MRMC-WMNs –Bottleneck identification –Local search of best new radio-to-link assignment at bottleneck –Channel reduction MRMC increases –Saturation throughput More channels, more throughput No significant increase with 4 radios –System spectral efficiency Peak at 3 to 5 channels with 3 or 4 radios

16. Sebastian Max Thank you for your attention! smx@comnets.rwth-aachen.de