1. PPM Sensitivity of 10 MHz OFDM Channels
doc.:IEEE /156r0
January 2004
January 2004
PPM Sensitivity of 10 MHz OFDM Channels
Mark Webster
Al Garrett
Mark Webster, GlobespanVirata
Mark Webster, GlobespanVirata

2. September 2003
Overview
15 PPM oscillators are more expensive than 20 PPM oscillators a specs 20 PPM.
For 10 MHz channels, the PPM frequency error impacts
Acquisition performance
Tracking performance
Acquisition was addressed in doc:IEEE /454r0
It was shown that a 20 PPM spec has no degradation on acquisition performance
This new submission addresses tracking performance
Mark Webster, GlobespanVirata

3. September 2003
Overview (cont’d)
Typical radio impairments are used to simulate 64 QAM 27 Mbps PER performance versus PPM error
Phase noise
PA distortion (EVM limited)
Tx/Rx filtering
DC notching using a HPF
It is shown that at worst-case PPM error (not typical) with the most sensitive 10 MHz modulation with 64 QAM at 27 Mbps, 20 PPM degradation is only 0.25 dB beyond 15 PPM’s degradation
Mark Webster, GlobespanVirata

4. Worst-Case Frequency Error for 10 MHz OFDM Channels
September 2003
Worst-Case Frequency Error for 10 MHz OFDM Channels
Set Frequency Error to Worst Case
Equivalent Osc. Spec
0 PPM spec
10 PPM spec
15 PPM spec
20 PPM spec
Mark Webster, GlobespanVirata

5. September 2003
Conclusion
This submission has shown that the extra cost of the 15 PPM oscillator can be avoided with a 20 PPM spec
The extra link degradation with a 20 PPM spec is small
About 0.25 dB
Using 20 PPM minimizes a design changes required to implement 10 MHz channels
Mark Webster, GlobespanVirata