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This presentation explores the performance of web browsing on wireless PDAs, analyzing data at the HTTP, TCP, MAC, and error levels. It identifies key issues and proposes future research areas.
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Multi-Layer Analysis of Web Browsing Performance for Wireless PDAs Adesola Omotayo & Carey Williamson January 6, 2020
Presentation Outline • Introduction & Motivation • Related Work • Data Gathering & Validation • HTTP-level Analysis • TCP-level Analysis • MAC-level & Error Analysis • Summary • Future Work
Introduction & Motivation • Widespread availability of WiFi hot spots • Limited understanding of multi-layer protocol interactions over IEEE 802.11b WLAN • Crucial to understand the performance of the wireless Web
Related Work • Workload of clients at wireline networks • Client-based • “Changes in Web Client Access Patterns”,P. Barford, A. Bestavros, A. Bradley, and M. Crovella, 1999 • Server-based • “Internet Web Servers: Workload Characterization and Performance Implications”,M. Arlitt and C. Williamson, October 1997 • Proxy-based • “On the Scale and Performance of Cooperative Web Proxy Caching”,A. Wolman, G. Voelker, N. Sharma, N. Cardwell, A. Karlin, and H. Levy, December 1999 • Workload of wireless clients • Local-area • “Analysis of a Local-Area Wireless Network”, D. Tang and M. Baker, August 2000 • Campus-area • “Analysis of a Campus-Wide Wireless Network”, D. Kotz and K. Essien, September 2002 • Metropolitan-area • “Analysis of a Metropolitan-Area Wireless Network”, D. Tang and M. Baker, August 1999
Internet Wired Network Access Point Wireless Sniffer Wireless Client Data Gathering & Validation • Selected websites • news, yellow pages, driving directions, stock quotes, educational resources, and downloadable PDA software • Over a period of 35 minutes • 398 TCP connections • 1.8% with expected FIN handshake • 96.5% used the RST packet • 1.7% unsuccessful connections A very simple workload AP: Netgear WAB 102 PDA: Compaq iPAQ 3600 Pocket PC, Windows CE, IE, MTU size of 1500 bytes Wireless Sniffer: Sniffer Pro 4.60.01, microsecond resolution timestamps
HTTP-level Analysis Server Response Time distinct plateaus consistent server response time response times < 200 ms Network RTT dominates the response latency Cache per-destination state information
HTTP-level Analysis Web Object Sizes • object sizes: 90% < 10 KB 2.5% > 40 KB • file types: most prevalent: GIF, JPG & HTML Least prevalent: PNG • largest objects transferred: executables Cache contents from wireless portals on Proxy Servers Increase support for PNG file type across browsers Compress executable files to be more compact
HTTP-level Analysis HTTP Transfer Time • HTTP transfers 96% < 1 second 2.5% > 2 seconds • larger objects take longer to download • few small objects have excessively long transfer times HTTP transfer times are generally low Most responses fit in a single TCP packet
TCP-level Analysis TCP Connection Type 13% were persistent 87% were non-persistent 4% of TCP connections sent > 10 HTTP requests 65% of HTTP transfers occurred on persistent connections As much as 73 HTTP requests were seen per connection Use persistent connections for all web sites
TCP-level Analysis TCP Connection Duration 75% sent < 20 packets 6% sent > 100 packets 80% sent < 10 KB 8% sent > 50 KB 75% lasted < 1 second 10% lasted > 30 seconds 4 connections lasted > 300 sec. Most TCP connections are non-persistent Most web object transfers are small Tightly set the persistent connection timeout
Distribution of TCP Connection Throughput 14 12 10 8 6 4 2 0 Frequency in Percent 0 0 2000004000006000008000001e+061.2e+06 Connection Throughput in bits per second (bps) TCP-level Analysis TCP Connection Throughput 95% < 400 Kbps Non-persistent TCP connections Small HTTP transfer size Non-negligible RTTs TCP slow start effects
MAC-level & Error Analysis MAC-level Retransmissions CRC Errors 3% of the packets 40% of the connections most retry attempts for a packet: 6 0.04% of the packets TCP-level Retransmissions HTTP-level Errors 0.2% of the packets 12 TCP connections 2 connection have > 3 packet loss Unsuccessful: 1% Successful: 96.74% Aborted: 2.26% Wireless channel quality does not have a major impact on wireless Web browsing performance
Future Work • Expand the work to a large scale traffic measurement • Study the effect of interference and range overlapping among closely located APs
References • M. Arlitt and C. Williamson, “Internet Web Servers: Workload Characterization and Performance Implications”, IEEE/ACM Transactions on Networking, Vol. 5, No. 5, pp. 631-645, October 1997. • P. Barford, A. Bestavros, A. Bradley, and M. Crovella, “Changes in Web Client Access Patterns”, World Wide Web Journal, 1999. • D. Kotz and K. Essien, “Analysis of a Campus-Wide Wireless Network”, Proceedings of ACM MOBICOM, Atlanta, GA, pp. 107-118, September 2002. • D. Tang and M. Baker, “Analysis of a Metropolitan-Area Wireless Network”, Proceedings of ACM MOBICOM, Seattle, WA, pp. 13-23, August 1999. • D. Tang and M. Baker, “Analysis of a Local-Area Wireless Network”, Proceedings of ACM MOBICOM, Boston, MA, pp. 1-10, August 2000. • A. Wolman, G. Voelker, N. Sharma, N. Cardwell, A. Karlin, and H. Levy, “On the Scale and Performance of Cooperative Web Proxy Caching”, Proceedings of ACM SOSP, December 1999.