IEEE 802.11-02/777 Steve Halford Jim Zyren May 2002 November 2002 Connectivity in 802.11a Steve Halford Jim Zyren Steve Halford, Intersil Steve Halford, Intersil Corp

November 2002 Goal Gauge the level of support for modifications to increase range and market acceptance of 802.11a Simple Modifications Low complexity Steve Halford, Intersil

Performance Issues for 802.11a November 2002 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

Importance of Connectivity November 2002 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

Problem The range issues of 802.11a will become very clear to users November 2002 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

How can we solve the range problem? November 2002 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

November 2002 Suggested Straw Poll “Should IEEE802.11 consider enhancements to improve the range of 802.11a?” Yes No Abstain 15/17/13 Steve Halford, Intersil