Submission Title: [Spectral Properties of tg4a Signals] Sept 2005 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Spectral Properties of tg4a Signals] Date Submitted: [30-Sep-2005] Source: [Laurent Ouvry, Samuel Dubouloz, Mathieu Sambuq] Company [CEA-Leti] Address [17 rue des Martyrs 38054 Grenoble] Voice:[+33-4-38-38-93-88 ], FAX: [+ 33-4-38-38-51-59 ], E−Mail: [laurent.ouvry@cea.fr; samuel.dubouloz@cea.fr; mathieu.sambuq@cea.fr] Re: [802.15.4a.] Abstract: [Spectral Properties of tg4a Signals] Purpose: [To promote discussion in 802.15.4a.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Objective Determine impact of : Sept 2005 Objective Determine impact of : Peak PRF Burst length Scrambling (polarity and time) Symbol duration (& mean PRF) on signal average power (with FCC definitions) L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Average Power Measurements Sept 2005 Average Power Measurements Measure in a 1MHz RBW Bandwidth Averaging time lower or equal to 1ms Use of functions given in doc #354r1-UWB-Power-Measurements L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Signal Models Burst composed by N pulses repeated at peak PRF Sept 2005 Signal Models Burst composed by N pulses repeated at peak PRF Symbol time Ts Mean PRF is therefore N/Ts Scrambling is used Pulse polarity codes Burst position scrambling codes L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Worst Case : No polarity code, no time scrambling Sept 2005 Worst Case : No polarity code, no time scrambling Signal can be expressed as: According to doc # 354r1: Burst of N impulsions p(t) Pulse Spectrum composed by spectral lines spaced by PRF and convolved by a sinc function of N/PRF width Burst every Ts TF Pulse PSD, lower than -41.3 dBm/MHz RBW < 1/Ts Spectral lines amplitudes, not depending on PRF RBW ≥ 1/Ts L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Example (No polarity code, no time scrambling) Sept 2005 Example (No polarity code, no time scrambling) Measurement Calculation -32.7362 PRF = 247 MHz Amplitude = -41.3 + 10*log10(RBW * N) – 60 = -32.26 Difference (negligible) is due to sinc Function sidelobes L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

No Modulation – No Time Scrambling Sept 2005 No Modulation – No Time Scrambling Burst Size (N) + 3 dB Y-scale is what is above –41.3dBm/MHz (in previous simple example, would be 8.6dB) identical L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Modulation Effects PPM Modulation Sept 2005 It is worst with PPM modulation only L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Modulation Effects (2) PPM + Polarity Sept 2005 PPM + Polarity is better than PPM only L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Time Scrambling Effects Sept 2005 Time Scrambling Effects  No Difference between simple modulation (2-PPM, 4-PPM) and fine time scrambling L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Polarity Codes Effect Sept 2005 Each pulse has a random polarity Standard deviation is about 0.25dB Polarity Codes are required for spectrum smoothing L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti

Sept 2005 Conclusions Peak PRF has no influence on the average transmitted power (w.r.t. FCC) Time scrambling has a minor effect on spectrum smoothing and is not better than PPM Modulation in this respect Random Polarity codes are required as soon as bursts of pulses are used Burst size and symbol time do not influence the spectrum anymore with random polarity codes A power backoff (margin) of about 1.5dB is required  compliant with doc # 605r1 L. Ouvry, S. Dubouloz, M. Sambuq CEA-Leti