By Bhanu Reddy Srinivas Madlapelli

1. A Comparison of VoIP Performance Over Three Routing Protocols for IEEE 802.11s-based Wireless Mesh Networks (WLAN mesh) By Bhanu Reddy Srinivas Madlapelli

2. Outline • Introduction • IEEE 802.11s standard • Routing in WMNs • Introduction to HWMP • VoIP performance Comparison in 3 protocols • Results • Conclusion • References

3. Introduction • Now Wireless mesh networks are becoming critical part of IP networks. • Routing in WMN has strong impact on capacity to support VoIP connections. • Here we compare three routing protocols in IEEE 802.11s based WMN. 1.AODV 2.DSR 3.HWMP

4. IEEE 802.11 standard • Widely accepted standard for Wireless Local Area Network (WLANs) • Because of its cost effective and its simple establishing wireless network. • In this context IEEE 802.11s group is designed to establish new extension of IEEE 802.11. • Multihop mesh networks techniques applied for interconnection of APs together that can build wireless connection to small-to-large scale WLANs.

5. Continues……. • This implementation is based on existing PHY layer of IEEE 802.11/a/b/g/n which are operating in 2.4-5 GHz unlicensed spectrum frequency band. • MAC layer supports multi radio/multichannel operation. And MAC routing protocol, MAC layer broadcast-multicast mechanism supports for extensive auto-configurability.

6. VoIP needs wide area wireless coverage for freedom of roaming. • For that tremendous works done on IEEE 802.11 capacity to support VoIP applications. • And showed VoIP packet aggregation mechanism to increase capacity of WMN to support many VoIP connections. • Also showed path selection(routing) in WMN has strong impact on capacity to support VoIP connections.

7. Routing in WMNs • Routing in WMNs is depending on routing protocol. • Mesh characteristics are different from MANET and mesh traffic is predominantly forwarded to and from wire-line gate way nodes by forming logical tree structure. • Many routing algorithms are proposed in WMN, by either proposing new routing protocol or adopting MANET routing protocol.

8. Introduction to HWMP • HWMP is proposed by 802.11 group and is based on radio metric. • Routing metrics affects the network performance. • Minimum weighted path selected by routing protocol must have good performance on terms of high throughput and low packet delay. • IEEE 802.11s WMNs uses airtime link metrics for calculation of link cost

9. HWMP • HWMP is default protocol for IEEE 802.11s WMN. • The word “Hybrid” refers it supports both reactive and proactive routing. • It supports two modes of operation depending on configuration. 1. On demand 2. Proactive

10. VoIP performance comparison in IEEE 802.11s • Simulation model To access capacity of each protocol they used Network simulator 2.It consists 50 nodes establish VoIP connections with each other has no background traffic. Each node has 2Mbps link and simulation time is 300 seconds, time period for each VoIP call is 20 seconds.

11. Results

16. Conclusion • Simulation results show the advantages of using HWMP over the other MANET protocols • AODV are not very effective due to hop count metrics • HWMP is effective because it addresses the shortcomings.

17. References [1] IEEE, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, IEEE Standard 802.11, June 1999. [2] IEEE, “Draft amendment: ESS mesh networking,” IEEE P802.11s Draft 1.00, November 2006. [3] IEEE 802.11e, Wireless LAN Medium Access Control (MAC) Enhancements for Quality of service (QoS), final 802.11e standard, July 2005. [4] L. Cai et al. “VoIP over WLAN: Voice capacity, admission control, QoS, and MAC”, In International Journal of Communication Systems 2006. [5] P. Wang et al. “IEEE 802.11e Enhancement for Voice Service”, In IEEE Wireless Communications magazine, February 2006

18. Thank you………