1. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 1 Lossless Data Compression: Data Compression can Significantly Increase Virtual Bandwidth in Wireless Networks Khurram Kazi kkazi@ieee.org Jeff Heath jheath@hns.com

2. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 2 Will the bandwidth supported by the existing and future wireless standards be enough? Once the fundamental issues of wireless networks’ security and mobility are addressed, it is expected that the wireless: –LANs and WANs will be widely deployed –Hotspots will be popping up at the airports, favorite hangouts, university campuses, trailer parks, and numerous other areas –More and more wireless networks will find their way into corporate infrastructure –Security, mobility, etc., will increasingly erode the amount of wireless bandwidth available for data.

3. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 3 Complimentary Solution to Optimized Air Interface Air interface due to the technology and physics allows certain data rate throughputs. Using complimentary techniques of lossless data compression the virtual bandwidth of wireless networks can be significantly increased Neutralize the affects of overhead introduced by security and mobility related functions Allows more users to send more data traffic at the hotspots where the wireless channel is shared.

4. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 4 Requirements for Data Compression in a Wireless Packet Network Compression must be lossless. Should execute efficiently with excellent compression when processing individual IP packets (Layer 1, etc.) Minimal latency Should not increase the packet size if uncompressible data is encountered –Use a bit to indicate if payload of the packet is already compressed (unused bit in header field) –Test compression ratio after 200 bytes or so and abort compression on the packet if not successful to that point Should be transparent to the end user once it is enabled Compression must be performed before data encryption

5. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 5 Standardized and Widely Used Compression algorithms Adopted by Standards Bodies and Forums to increase data throughput –ITU-T V.42bis (LZW) primarily used for modem applications –ITU-T V.44 (LZJH) adopted for use in modems but originally designed for packet networks –ANSI X3.241 (LZS) Stac algorithm used in packet networks ZIP (PKZIP, WinZIP, Deflate) two pass algorithms used primarily for compression of a file prior to and separate from network handling

6. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 6 Does it make sense to introduce compression in wireless networks Typical user in corporate wireless networks –Web access –Email –Instant message –Application software –VPN Social/Home-user –Web access –Email –Instant messaging

7. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 7 Does it make sense to introduce compression in wireless networks Web access, Emails, Instant messaging, application text data; the major source of traffic traversing wireless network – All have a great deal of redundancy in the data making them ideal for lossless compression Compression before data encryption offsets the encryption burden by reducing the amount of data encrypted and time to encrypt Compression enhances encryption efficiency and security by removing redundancy from the plaintext and thus thwarting cryptanalysis.

8. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 8 Compression ratios of HTML files using various compression algorithms (original file size/compressed file)

9. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 9 Compression ratios of HTML files using various compression algorithms (original file size/compressed file)

10. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 10 Compression ratios of HTML files using various compression algorithms (original file size/compressed file)

11. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 11 Comparisons between V.44 and WinZIP (original frame size/compressed frame) Sample frames captured while accessing www.yahoo.com

12. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 12 Virtual Bandwidth

13. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 13 Side benefits of data compression The compression will enhance encryption efficiency and security by minimizing the amount of data to be encrypted, and by removing redundancy from the plaintext and thus thwarting cryptanalysis.

14. doc.: IEEE 802.11-03/535r0 Submission July 2003 Khurram Kazi ECDD Tech, Jeff Heath Hughes Networks Slide 14 Conclusion Introducing lossless data compression can significantly increase the virtual bandwidth in wireless networks Based on the traffic patterns Compression ratios up to 7:1 have been reported. Our preliminary analysis shows that on an average ratios of 2:1 are seen Enhances the Encryption efficiencies Seriously consider introduction of V.44 or equivalent compression algorithm as a possible compression scheme for 802.11 networks to achieve significant bandwidth gains (compliments optimized air interface schemes)