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Connectivity in 802.11a
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Connectivity in 802.11a

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  1. Connectivity in 802.11a Steve Halford Jim Zyren Steve Halford, Intersil

  2. Goal • Gauge the level of support for modifications to increase range and market acceptance of 802.11a • Simple Modifications • Low complexity Steve Halford, Intersil

  3. Performance Issues for 802.11a • 802.11a offers advantages over 2.4 GHz • Currently less ‘crowded’ with interference • Offers more channels for re-use • Better Throughput for equivalent data rates • Smaller preamble • Shorter Slot intervals • 802.11a range is less than 802.11b/g range • Higher theoretical path loss at 5 GHz • Confirmed by testing of available 802.11a & 802.11b/g equipment Steve Halford, Intersil

  4. Importance of Connectivity • Basic connectivity may not be possible in 802.11a • Test show that 6 Mbps range is much less than range of 1 & 2 Mbps • Higher loss & higher SNR required • Why is this a problem? • For home networks -- Range equals Performance • Home networks are fed by internet connections @ rates < 2Mbps • Higher throughput not required • Complete coverage of home is critical • Small enterprise applications need coverage • Small number of AP’s is desired • Users expect rates comparable to their home networks • Check e-mail & IM don’t require 54 Mbps type rates Steve Halford, Intersil

  5. Problem • The range issues of 802.11a will become very clear to users • 802.11b users will expect same range with higher data rates • 802.11g users will enjoy 54 Mbps data rates & have the connectivity of 802.11b • Range issue could overwhelm the advantages of the 5 GHz spectrum! Steve Halford, Intersil

  6. How can we solve the range problem? • Increased Coding • Lower rate, better range • Could be as simple as repetition coding • Or, could add interleaver & outer block code • Ex: Reed-Solomon outer code • Expand 802.11b to 5 GHz band • Make 5 GHz look a little like 802.11g • Longer preamble • More robust initial detection • Enable the practical use of spatial diversity • Even simple switch diversity is a problem for 802.11a Steve Halford, Intersil

  7. Suggested Straw Poll “Should IEEE802.11 consider enhancements to improve the range of 802.11a?” • Yes • No • Abstain • 15/17/13 Steve Halford, Intersil