1. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 1 Jeonghun Noh Deepesh Jain A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs

2. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 2 Outline Introduction –Motivation, RaDiO vs. CoDiO, intuition behind CoDiO Problem Identification : Dedicated Line vs. Shared WLAN Channel Estimation Techniques Simulation Results on dynamic wireline and WLANs Conclusions

3. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 3 Motivation A huge success of video streaming over the Internet Requirements –A small buffer at the receiver –Small delay of user control and short preroll delay Research done in the network parts –Reservation based Routing Protocols : RSVP –QoS support : diffserv, interv –Priority queue at the network layer and the Link Layer Research done in the application parts –Frame reordering, ARQ, RaDiO, CoDiO

4. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 4 RaDiO vs CoDiO RaDiO : An optimal transmission policy for each packet determined by minimizing D+λR –D : expected distortion according to the current policies –R : expected transmission rate CoDiO : An optimal transmission policy for each packet determined by minimizing D+λΔ –D : expected distortion according to the current policies –Δ : expected congestion in the network (last hop) –Delay on the last hop is determined by the size of the queue CoDiO achieves the same R-D performance yet reduces congestion

5. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 5 4 4 Why CoDiO performs better? Intuition behind CoDiO CoDiO and RaDiO send virtually the same set of packets Big difference comes from how to order them time 2 1 3 1 3 2

6. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 6 Problem Identification Why WLANs? –Becoming popular as the last hop –Provide more bandwidth than 3G/4G cellular system Why hard? –Bandwidth fluctuation –Shared medium with multiple users –No guarantee of QoS service Differences with the previous work –Available bandwidth is no longer fixed –Multiple users share the same wireless channel

7. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 7 consideration of WLANs Channel Capacity fluctuates –mobile movement –interference from electronic devices –Other users sharing bandwidth For CoDiO, Channel Capacity is important for delay estimation –Determines drain rate of packets at the bottleneck link time Queue size Drain rate

8. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 8 Inputs to RaDiO/CoDiO Issue: To measure current available bandwidth Need: New Bandwidth Estimation technique RaDiO/CoDiO Video Info Network Bandwidth Optimal Scheduling Policy

9. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 9 Channel Estimation Technique 1 Packet-pair to estimate the bottleneck link capacity

10. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 10 Channel Estimation Technique 2 Loss Delay based algorithm (LDA) –measures current available channel bandwidth Initial Bandwidth Estimate Send Packets Packet Lost Packed received late Decrease Capacity Increase Capacity NO Yes B: Bandwidth C: Capacity Rf: Reduction factor If: Increment factor AIR: Additive increment rate

11. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 11 Network Simulation Setup - Wireline Network path composed of high bandwidth link and low bandwidth last hop Channel Capacity Fluctuating Random cross traffic last hop Video traffic Acknowledgements High bandwidth links PI

12. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 12 Network Simulation Setup - WLAN Network path composed of high bandwidth link and wireless last hop Channel traffic varying Random cross traffic last hop Video traffic Acknowledgements High bandwidth links PI

13. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 13 Video / background traffic setup Layered video stream encoded with H.263+ Network experiments in ns-2 over a 2-link path 22Mbps of exponential cross traffic T3 link Wireline / WLAN Video traffic Traffic over WLAN

14. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 14 Comparison results : Dynamic Wireline Simulations using H.263+ Rate : 10 fps ( 1 view every 100ms) Sequence : Foreman Layered Coding : BL32kbps,EL32kbps Sequence length : 24s Preroll delay : 600ms Capacity change (50-34Kbps every sec) Capacity estimation using burst packets Optimistic (Cap = Cap estimated)

15. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 15 Comparison results : Dynamic Wireline Simulations using H.263+ Rate : 10 fps ( 1 view every 100ms) Sequence : Foreman Layered Coding : BL32kbps,EL32kbps Sequence length : 24s Preroll delay : 600ms Capacity change (50-34Kbps every sec) Capacity estimation using burst packets Pessimistic (Cap = Cap estimated*f) f<1

16. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 16 4 4 Why CoDiO performs worse? RaDiO sends packets aggressively at the beginning CoDiO distributes packets over time to reduce congestion time 2 1 3 1 3 2

17. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 17 Comparison results : WLAN Simulations using H.263+ Rate : 10 fps ( 1 view every 100ms) Sequence : Foreman Layered Coding : BL32kbps,EL32kbps Sequence length : 24s Preroll delay : 600ms Capacity = 130Kbps Bandwidth = 60Kbps No Traffic

18. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 18 Comparison results : WLAN Simulations using H.263+ Rate : 10 fps ( 1 view every 100ms) Sequence : Foreman Layered Coding : BL32kbps,EL32kbps Sequence length : 24s Preroll delay : 600ms Capacity = 130Kbps Bandwidth = 60Kbps Traffic = 64Kbps

19. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 19 Comparison results : WLAN with LDA Simulations using H.263+ Rate : 10 fps ( 1 view every 100ms) Sequence : Foreman Layered Coding : BL32kbps,EL32kbps Sequence length : 24s Preroll delay : 600ms Capacity = 130Kbps Traffic = 80Kbps (on/off every sec) Bandwidth estimation using LDA

20. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 20 Conclusion Summary –R-D curve for RaDiO & CoDiO similar (WLAN) –RaDiO aggressive creating more congestion (WLAN) –CoDiO reduces congestion (WLAN) –CoDiO more sensitive to available bandwidth –Need a good bandwidth estimation technique like LDA Future work –Design a stochastic model of delay estimation –Analyze the effect of varying Capacity to transmission Rate –More general network configurations

21. A Comparison of RaDiO and CoDiO over IEEE 802.11 WLANs May 25 th 2004 21 Acknowledgement Professor Girod –Valuable discussion and feedback on intermediate results Eric Setton –Wonderful code and guidance to a meaningful project result –Allowed us to use his slides for the presentation Anonymous peer reviewers –Help us to identify the project scope (not too ambitious!) All the valuable questions and feedback so far!