Spectral Control Issues for TGg

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					November 2002                   doc.: IEEE 802.11-02/777r0




  Connectivity in 802.11a



                Steve Halford
                  Jim Zyren




Submission           Slide 1               Steve Halford, Intersil
November 2002                   doc.: IEEE 802.11-02/777r0

                     Goal

 • Gauge the level of support for
   modifications to increase range
   and market acceptance of
   802.11a
       – Simple Modifications
       – Low complexity



Submission            Slide 2              Steve Halford, Intersil
 November 2002                                 doc.: IEEE 802.11-02/777r0

          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

 Submission                          Slide 3              Steve Halford, Intersil
November 2002                                          doc.: IEEE 802.11-02/777r0

                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

Submission                             Slide 4                    Steve Halford, Intersil
November 2002                          doc.: IEEE 802.11-02/777r0

                       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!


Submission                 Slide 5                Steve Halford, Intersil
November 2002                                      doc.: IEEE 802.11-02/777r0

  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

Submission                         Slide 6                    Steve Halford, Intersil
November 2002                       doc.: IEEE 802.11-02/777r0

                 Suggested Straw Poll

 “Should IEEE802.11 consider
   enhancements to improve the range of
   802.11a?”

             • Yes
             • No
             • Abstain
             • 15/17/13

Submission                Slide 7              Steve Halford, Intersil

				
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