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

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

3. Performance Issues for 802.11a
November 2002
Performance Issues for a
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 b/g range
Higher theoretical path loss at 5 GHz
Confirmed by testing of available a & b/g equipment
Steve Halford, Intersil

4. Importance of Connectivity
November 2002
Importance of Connectivity
Basic connectivity may not be possible in a
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 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 & 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
November 2002
Problem
The range issues of a 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 b
Range issue could overwhelm the advantages of the 5 GHz spectrum!
Steve Halford, Intersil

6. 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 b to 5 GHz band
Make 5 GHz look a little like g
Longer preamble
More robust initial detection
Enable the practical use of spatial diversity
Even simple switch diversity is a problem for a
Steve Halford, Intersil

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