1. doc.: IEEE 802.11-01/xxxr0 Don Sloan, Cisco Systems November 13, 2001
6/3/2018
doc.: IEEE /xxxr0
.11g Higher Rate Modulation Compatible with .11a for Dual Band Radio Devices
Don Sloan, Cisco Systems
November 13, 2001
Don Sloan, Cisco Systems
Don Sloan, Cisco Systems

2. This presentation supports
This presentation supports .11g Higher Rate employing OFDM consistent with .11a for dual-band devices
WHY?
Dual-Band (2.4 & 5GHz) STA radios are a natural evolution in systems.
Much as dual-band and tri-band cellular phones allow seamless roaming across networks, dual- band STA radios would support seamless roaming on all networks (.11b and .11a).
Public access with 2.4GHz in some areas, 5GHz in others.
Don Sloan, Cisco Systems

3. Designing the .11g Higher Rate Standard with the same OFDM modulation as .11a makes dual-band STA devices practical.
Uses the same Encoder/Decoder circuitry for both bands
Same development and support knowledge for both bands
With a common higher rate in .11g and .11a the two bands are effectively merged into one larger set of high rate channels.
Don Sloan, Cisco Systems

4. Compatibility has some downside:
.11b Header is long, impacting Higher Rate throughput.
Eventually OFDM will likely proliferate replacing CCK in many systems allowing (optional) ultra-short headers with better throughput.
We had a similar situation when 11Mbps short headers were introduced as optional in 1&2 Mbps systems.
Don Sloan, Cisco Systems

5. Both 802.11 bands viewed as one standard
Conclusion:
The 2.4GHz band migrates up in bit rate with a visible future consistent with the emerging 5GHz systems.
Both bands viewed as one standard
.11g radios would use the same circuitry and technology as .11a in dual band radios
OFDM received the most votes last time and is the apparent choice, let’s get behind it and move forward.
Don Sloan, Cisco Systems