1. Jim Zyren Mark Webster Steve Halford Intersil Corporation
March 2001
TGg Final Statement
Jim Zyren
Mark Webster
Steve Halford
Intersil Corporation
J. Zyren, M. Webster, S. Halford, Intersil Corp

2. OFDM for IEEE 802.11g CCK / OFDM Industry Convergence
March 2001
CCK / OFDM
Fully compliant with TGg requirements
Backward compatible with IEEE b
Utilizes a as a basis for the higher data rates
Data rates identical to a (6,9,12,18,24,36,48,54 Mbps)
Industry Convergence
OFDM already adopted for a & HiperLAN2
Uses technology developed by MANY companies
Regulatory Issues
All TGg proposals require rule change
FCC is changing rules
Do we want to enable another hi rate technology?
Inevitable direct competition with 2.4 & 5 GHz
J. Zyren, M. Webster, S. Halford, Intersil Corp

3. March 2001
Regulatory Status
None of the TGg proposals meets the FCC requirements for 2.4 GHz DSSS systems
FCC considers spectral efficiency to be a key component
Meeting processing gain or CW jammer test alone is not sufficient
FCC has compelling reasons to modify 2.4 GHz DSSS rules:
WiLan Application for Review
TI proposal for PBCC
Current proceeding (99-231) regarding DSSS testing
Consumer demand for higher data rates
FCC is planning to initiate a rule making process to change the rules for DSSS systems in the 2.4 GHz band
Expected to redefine “DSSS” to permit higher data rates
Likely initiated in the spring timeframe
OFDM is coming to the 2.4 GHz band
OFDM (Wi-LAN) has been turned down
TI has never obtained regulatory approval for PBCC
J. Zyren, M. Webster, S. Halford, Intersil Corp

4. Why OFDM for 2.4 GHz? OFDM is a powerful and proven waveform
March 2001
OFDM is a powerful and proven waveform
Selected for both a and HyperLan2
Robust performance against multi-path, AWGN, and in-band interference
Real world performance impacts
Interleaving and error coding result in very robust performance
Data rates to 54 Mbps
Industry Convergence
Many companies are developing OFDM technology
Industry working to develop a single 5 GHz standard for the 5 GHz bands
5 GHz IAG and IEEE GSG
Provide graceful migration path from b to a
CCK-OFDM offers forward & backward compatibility
OFDM is being widely adopted
TGg should capitalize on this development --- not resist it!
J. Zyren, M. Webster, S. Halford, Intersil Corp

5. Comparison of PBCC and OFDM
March 2001
PBCC was adopted by IEEE on the same day as CCK but no PBCC based products are on the market
Design complexity delays practical implementation
WLAN channels are limited by multi-path not AWGN
Convolutional codes emphasize AWGN performance but complicate receiver via complex equalization requirements
By comparison, CCK block codes are optimized for multi-path properties
Block codes are selected for autocorrelation and cross correlation properties
Lowers receiver complexity and speeds implementation
Similarly, OFDM characteristics are well suited to WLAN applications
Robust performance against multi-path, in-band interference and AWGN
Receiver scales to higher data rates with no increase in complexity
PBCC is more differentiated from CCK than OFDM
PBCC is not optimized to address real world WLAN effects
PBCC requires the use of an entirely different receiver structure
J. Zyren, M. Webster, S. Halford, Intersil Corp

6. Some Closing Thoughts
March 2001
Single carrier systems do not scale well to higher data rates
Selection of PBCC will effectively cap data rates and require the standardization of yet another technology
TGg should adopt the fastest technology for the HI RATE EXTENSION
OFDM provides for data rates to 54 Mbps
Complements a
Speeds WLAN adoption in BOTH 2.4 & 5 GHz bands
OFDM will likely come into the band regardless of what the IEEE does
IEEE should standardize around OFDM
OFDM is the right choice for TGg
J. Zyren, M. Webster, S. Halford, Intersil Corp