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IEEE 802.11g Characteristics. Following is not in the Course textbook but is an important topic. The material is based upon several whitepapers Jerry Bernardini. 802.11 Summary Characteristics. 802.11g Requirements. Backward compatible with 802.11b Higher throughput than 802.11b
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IEEE 802.11g Characteristics Following is not in the Course textbook but is an important topic. The material is based upon several whitepapers Jerry Bernardini CCRI J. Bernardini
802.11 Summary Characteristics CCRI J. Bernardini
802.11g Requirements Backward compatible with 802.11b Higher throughput than 802.11b Mixed mode operation CCRI J. Bernardini
802.11g Protection • Before an 802.11g client can transmit to an 802.11g AP it must reserve the medium. • Must transmit so 802.11b will understand. • Two Protection Methods • CTS-to self at 802.11b modulation (slow Clear to Send) • RTS-CTS at 802.11b modulation • CTS-to-self is more efficient but may not be seen by hidden-node • RTS-CTS is more reliable but has more overhead • Both Methods dramatically reduce the 802.11g throughput CCRI J. Bernardini
802.11b/g Mixed Mode Operation Station802.11g Station802.11g AP 802.11g Station802.11b 1-Slow CTS 2-Slow CTS 2-Slow CTS 3-Fast Data 3-Fast Data 3-Fast Data CCRI J. Bernardini
Protection Throughput Effect CCRI J. Bernardini
802.11g Conclusions • 802.11g is significantly faster then 802.11b for all conditions • 802.11b station associating with a 802.11g network drops throughput due to protection • 802.11b station does not have to be active to reduce throughput (just associated ) • Mixed 802.11b/g deployments are likely to be common for the foreseeable future • Mixed 802.11b/a deployments will have higher throughput • 802.11b/g/n will also have to provide protection CCRI J. Bernardini
802.11g References • When is 54 not equal to 54? A look at 802.11a, b, g Throughput, Matthew Gast, www.oreillynet.com/lpt/a/4085 • The New Mainstream Wireless LAN Standard, IEEE802.11g White Paper, Broadcom, www.54g.org/802.11g-WP104-R • IEEE 802.11g New Draft Standard Clarifies Future of Wireless LAN, William Carney, Texas Instrument • The IEEE 802.11g Standard for High Data Rate WLANs, IEEE Network, May/June 2005 • Intersel triples 802.11g date rates, Tony Smith, The Register, 16 April 2003 • Maximizing Your 802.11G Investment, White Paper, Proxim Wireless Networks, 2003 • Deploying High Capacity Wireless LANS, White Paper, Cisco Systems • Project: Wireless Throughput, Adrian Fisher, AVF0714@ecu.edu, April 12, 2007 CCRI J. Bernardini