September 2000 doc IEEE 802 11 -00 294

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September 2000 doc. : IEEE 802. 11 -00/294 Suggested PA Model for 802. 11 HRb Mark Webster Intersil Corporation September, 2000 Submission 1 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Overview • This presentation describes a power amplifier non-linearity for 802. 11 HRb proposal use. • The PA impacts spectral mask. • The PA impacts packet-error-rate. • The model is a fair representation of solid-state power amplifiers. • The model is easy to use. • Used by 802. 11 a. • OFDM for Wireless Multimedia Communications Richard van Nee, Ramjee Prasad, Artech House, 2000 Submission 2 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Effect of Power Amplifier 11 MHz Chip rate QPSK Signal NRZ Filter 5 th Order Butterworth Filter Rapp PA (p = 2) 3. 5 d. B Output Backoff Power Spectrum after PA Historical Signal Power Spectrum before PA Submission 3 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 General PA Model Power Amplifier Time-varying Signal Envelop Matlab Abs(*) AM/AM Distortion Amplitude of Envelope AM/PM Distortion Phase of Envelope + Matlab Angle(*) Submission 4 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Recommended PA Model Fairly Representative of Solid State Amplifiers Power Amplifier Matlab Abs(*) RAPP AM/AM Distortion Amplitude of Envelope Phase of Envelope Matlab Angle(*) Submission 5 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 RAPP Model for AM/AM RAPP Model for PA AM/AM Distortion 0 d. B Output Back-Off from Full Saturation Ref. IEEE 802. 11 -97/123 Submission 6 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Output Power Description: 1 d. B Compression Point vs. Full Saturation 1 2 3 4 "p" parameter 5 6 7 8 9 10 0 -1 d. B Units Output Power (d. B) -2 -3 -4 -5 -6 Output Power at 1 d. B Compression Point Saturation Point -7 -8 -9 -10 Submission 7 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 How to Specify Drive Level OPTIONS 1. PA input back-off from 1 d. B Compression point. 2. PA output back-off from 1 d. B Compression point. 3. PA output back-off from full saturation. COMMENTS • 1 d. B compression point is amplifier model dependent. • Output from full saturation is directly usable in link budget calculations. Submission 8 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Practical Matters 2 x to 4 x over sample TX Packet Add multipath, noise and send to Receiver RAPP Model Gain Adjust for Desired OBO Submission Measure Average Packet Power 9 Output Back-off (OBO) from Full Saturation M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Matlab Code %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Rapp. Pa. m % % RAPP model of a power amplifier. % % Input: Vector of complex numbers. % Output: Vector of complex numbers with same dimension as input. % % Mark Webster September 18, 2000 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function y = Rapp. Pa( x, p ) denom = (1 + abs(x). ^(2*p)). ^ (1/(2*p)); y = x. / denom; Submission 10 M. Webster

September 2000 doc. : IEEE 802. 11 -00/294 Summary • Recommend use of RAPP PA model. • Use p=2 and p=3. • Measure output back-off (OBO) from full saturation to specify the drive level. • Over-sample signal 2 x to 4 x. • Show influence on spectrum (mask). • Show influence on Carrier Degradation in AWGN. Submission 11 M. Webster

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