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Delay Bound Rich Image Delivery over WLANs

Delay Bound Rich Image Delivery over WLANs . Shira S. Krishnan Georgia Tech, ECE Multimedia Communications Laboratory. Introduction. Wireless LANs are being used extensively across homes, offices and campuses.

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Delay Bound Rich Image Delivery over WLANs

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  1. Delay Bound Rich Image Delivery over WLANs Shira S. Krishnan Georgia Tech, ECE Multimedia Communications Laboratory

  2. Introduction • Wireless LANs are being used extensively across homes, offices and campuses. • The 802.11b/g technology, popular today is used for low bandwidth requirements like voice, data and low density image applications. • For high density image and hi-def video transmission, next generation 802.11 technologies like 802.11n are being considered. • Compatibility of 802.11n with existing 802.11b/g or 802.11a installations is also of great interest.

  3. Background A comparison of 802.11 technologies is listed in the table below • Protocol

  4. 802.11n 802.11n provides great advantages in terms of higher bandwidth and range • Reliability - Greater SNR • Predictable Coverage – Use of multiple spatial streams means fewer dead spots in a coverage area • Throughput – Higher data rates It achieves this through a variety of MAC enhancements like • Frame Aggregation – Mac Service Data Unit (MSDU) and Message Protocol Data Unit (MPDU) aggregation – single radio preamble for each transmission; Maximum frame size increased to 64 KB • MSDU – More efficient – Aggregation of Ethernet frames; MPDU – Aggregation of 802.11 frames • Block Acknowledgements – Ack for aggregated frames • Reduced Inter-frame Spacing – Lower overheads; can be used only in greenfield deployments

  5. Traffic of Interest • Traffic of Interest is High Density Images that have a delay bound of 5 seconds. • Three different sizes of images are considered for analysis -- 10, 100 and 1000 Mb images • Analysis of these images is done in the raw format, Mathematically lossless compressed form of 2:1 and Diagnostically lossless compressed form of 10:1

  6. Interactive time as a parameter • For certain applications like image conferencing, reliable transmission is necessary over the network within specified time know as the interactive time • For such application TCP will have to be used to ensure reliability and high speed network used as a transmission medium to ensure satisfaction of delay bound requirements

  7. Problem Definition • Identify a wireless system that is most suited for rich media delivery within a set interactive timeframe using a network designed to handle other forms of traffic.

  8. Assumptions • Packet losses not considered • Wireless link failures not considered • 802.11n draft 2.0 specs used to model systems • Ns2 models modified suitably to reflect the scenario of interest

  9. Results Size in Mb

  10. Theoretical Values

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