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1 L U N D U N I V E R S I T Y QoS Provisioning in Wireless Mesh Networks Ali Hamidian and Ulf Körner Fourth EuroNGI/FGI Workshop on Wireless and Mobility.

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Presentation on theme: "1 L U N D U N I V E R S I T Y QoS Provisioning in Wireless Mesh Networks Ali Hamidian and Ulf Körner Fourth EuroNGI/FGI Workshop on Wireless and Mobility."— Presentation transcript:

1 1 L U N D U N I V E R S I T Y QoS Provisioning in Wireless Mesh Networks Ali Hamidian and Ulf Körner Fourth EuroNGI/FGI Workshop on Wireless and Mobility January , Barcelona, Spain

2 2 L U N D U N I V E R S I T Y Outline Overview of IEEE e EDCA with Resource Reservation (EDCA/RR) Multi-hop resource reservation in EDCA/RR Summary

3 3 L U N D U N I V E R S I T Y IEEE e and HCF e introduces hybrid coordination function (HCF), which has 2 medium access methods: – enhanced distributed channel access (EDCA) – HCF controlled channel access (HCCA) HCF introduces 2 new concepts: – transmission opportunity (TXOP): A bounded time interval during which a station may transmit multiple frames – traffic specification (TSPEC): Contains information about the QoS expectation of a traffic stream (frame size, service interval, data rate, burst size, delay bound, etc.)

4 4 L U N D U N I V E R S I T Y EDCA HCCA Contention-based “Enhanced DCF” Distributed Service differentiation Contention-free “Enhanced PCF” Centralized Resource reservation

5 5 L U N D U N I V E R S I T Y Motivation of EDCA/RR: QoS Limitations in e Problem with EDCA – Contention-based medium access & no distributed admission control ==> not possible to guarantee QoS Problem with HCCA – Centralized infrastructure requirement ==> HCCA not useful in ad hoc/mesh networks We need a solution which is – Contention-free (unlike EDCA) Remove the random medium access delays – Distributed (unlike HCCA) Remove the need of an access point

6 6 L U N D U N I V E R S I T Y Outline Overview of IEEE e EDCA with Resource Reservation (EDCA/RR) Multi-hop resource reservation in EDCA/RR Summary

7 7 L U N D U N I V E R S I T Y EDCA/RR Operation EDCA/RR is similar to EDCA as long as the stations are sending LP-frames (which do not need resource reservation). source destination

8 8 L U N D U N I V E R S I T Y EDCA/RR Operation When an HP-stream needs to reserve resources, EDCA/RR in the source checks whether its own new stream can be admitted. source destination

9 9 L U N D U N I V E R S I T Y EDCA/RR Operation If admission control OK: schedule the new stream broadcast ADDTS request containing TSPEC wait for ADDTS response ADDTS request source destination

10 10 L U N D U N I V E R S I T Y EDCA/RR Operation Once all ADDTS responses are received by the source, it waits until its first reserved TXOP at service start time & starts transmitting. ADDTS response source destination

11 11 L U N D U N I V E R S I T Y EDCA/RR Operation Now the source has periodic and contention-free access to the medium. HP data frames source destination

12 12 L U N D U N I V E R S I T Y Simulation Setup EDCA/RR implementation in ns-2.26 based on Mike Moreton’s enhanced /802.11e implementation EDCA vs. EDCA/RR The impact of (hidden) LP-streams on an HP- stream HP stream (AC_VO): G.711, 180 B, UDP datagrams every 20 ms LP stream (AC_BE): FTP, 1000 B, TCP segments

13 13 L U N D U N I V E R S I T Y Average End-to-End Delay - 0 % packet error no. of LP- streams average end-to-end delay (ms) 99 % confidence interval (ms) EDCAEDCA/RREDCAEDCA/RR (0.69,0.69)(12.13,12.53) (6.20,6.22)(12.02,12.42) (11.14,11.19)(12.08,12.47) (13.90,13.96)(12.01,12.42) (17.08,17.16)(12.19,12.57) (20.46,20.56)(12.06,12.45)

14 14 L U N D U N I V E R S I T Y Outline Overview of IEEE e EDCA with Resource Reservation (EDCA/RR) Multi-hop resource reservation in EDCA/RR Summary

15 15 L U N D U N I V E R S I T Y Motivation: Why EDCA/RR for Wireless Mesh Networks (WMNs)? EDCA/RR (with multi-hop capability) is especially well-suited for static wireless networks, like WMNs IEEE s for mesh networks is based on EDCA, so it is not too difficult/unrealistic extending s to support EDCA/RR

16 16 L U N D U N I V E R S I T Y Motivation: Why EDCA/RR for Wireless Mesh Networks (WMNs)? Results from a 4-hop g WMN CS = Counter Strike server to clients: ( × n) B every 60 ms clients to server: 42 B every 50 ms

17 17 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR Combined route discovery (AODV) and resource reservation (EDCA/RR) – search for route fulfilling the QoS requirements – faster route discovery/resource reservation Why AODV? Because it will be part of HWMP (Hybrid Wireless Mesh Protocol), which is the default routing protocol suggested in s – reactive part: RM-AODV (Radio Metric AODV) – proactive part: tree-based routing

18 18 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR An HP-packet is sent down the protocol stack and reaches the routing protocol (AODV). ABC RRQ (route and reservation request) is a RREQ extended with some TSPEC fields. 1.Copy TSPEC from HP-packet to RRQ 2.Do admission control 3.Temporarily mark resources as reserved and broadcast RRQ

19 19 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR ABC 1.Copy TSPEC from RRQ 2.Do admission control 3.Temporarily mark resources as reserved and rebroadcast RRQ

20 20 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR ABC 1.Copy TSPEC from RRQ 2.Do admission control 3.Schedule the traffic request and send a RRP

21 21 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR ABC Schedule traffic and forward RRP

22 22 L U N D U N I V E R S I T Y Multi-hop Resource Reservation in EDCA/RR ABC Schedule traffic; TXOP reservation done

23 23 L U N D U N I V E R S I T Y Summary EDCA/RR – is a MAC scheme with distributed admission control and scheduling – allows stations to reserve TXOPs for periodic and contention-free medium access – suites well for WMNs


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