<month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Analysis of Time Variance of a UWB Propagation Channel (Slides)] Date Submitted: [5 November 2002] Source: [Steve Schell] Company [Bitzmo, Inc] Address [2130 Gold St. Suite 250, P.O. Box 1180, Alviso CA 95002] Voice:[+1-408-273-4529], FAX: [+1-408-273-4628], E-Mail:[schell@bitzmo.com] Re: [] Abstract: [An analysis of Intel’s channel measurements suggests that a 500-MHz wide channel can change as little as - 20 dB (10% NRMSE) over a duration of 60 milliseconds in the presence of an object moving at pedestrian speeds near the line-of-sight path. The analysis also suggests that the channel can change completely (100% NRMSE) over the same or smaller duration. The corresponding assumptions on packet-to-packet correlation are “high correlation” and no correlation, respectively. A recommendation is made to consider both scenarios in the evaluation of PHY proposals.] Purpose: [A sequence of UWB propagation channel impulse responses measured by Intel is analyzed to assist the 802.15.3a Study Group in determining whether to consider only propagation channels that are uncorrelated from packet to packet, or only those that are invariant from packet to packet, or both.] 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. Steve Schell, Bitzmo Inc <author>, <company>

Analysis of Time Variance of a UWB Propagation Channel* November 2002 Analysis of Time Variance of a UWB Propagation Channel* Steve Schell Bitzmo, Inc *see also 02/452 for accompanying paper Acknowledgement: Thanks to David Cheung and colleagues at Intel for making their channel measurements (on which this work is based) available to the UWB community. Steve Schell, Bitzmo Inc

Is a UWB channel correlated or uncorrelated from packet to packet? <month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Is a UWB channel correlated or uncorrelated from packet to packet? Motivations: understand the application environments in which a UWB-enabled consumer electronics device would operate contribute to SG3a / TG3a PHY evaluation process proposals that depend on time-variance or time-invariance should have weaknesses evaluated proposals that can smartly exploit time-variance or time-invariance should be allowed to shine Steve Schell, Bitzmo Inc <author>, <company>

Starting Point: Intel measurement data November 2002 Starting Point: Intel measurement data Sequence of impulse responses versus position of a water container 2-8 GHz measurement band data on USC ftp site Steve Schell, Bitzmo Inc

Intuition: Channel correlation vs. position varies from high to low November 2002 Intuition: Channel correlation vs. position varies from high to low high correlation LOS: water blockage out on the edges low correlation NLOS: water blockage in the LOS path Steve Schell, Bitzmo Inc

Analysis: Channel similarity from position to position November 2002 Analysis: Channel similarity from position to position Methodology Compute prediction error between channel impulse responses x(t,f) & y(t,f) from adjacent positions, as a function of center frequency f : prediction error Steve Schell, Bitzmo Inc

Results: Channel similarity from position to position November 2002 Results: Channel similarity from position to position Results for 500 MHz bandwidth {mean,min,max,etc} over all f of prediction_error(position) Steve Schell, Bitzmo Inc

Results: Channel similarity from position to position November 2002 Results: Channel similarity from position to position Results for 2000 MHz bandwidth {mean,min,max,etc} over all f of prediction_error(position) Steve Schell, Bitzmo Inc

Discussion of position-by-position results <month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Discussion of position-by-position results Transition regions water moves from non-blocking to blocking LOS path channel impulse response changes a lot prediction error up to 0 dB NRMSE or 100 % Stable regions propagation remains LOS (or NLOS) channel impulse response changes a little prediction error as little as -20 dB NRMSE or 10 % Overall channel impulse response changes by anywhere from -20 dB (10% NRMSE) to 0 dB (100% NRMSE) with a 2-inch change in water position Steve Schell, Bitzmo Inc <author>, <company>

<month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Re-interpretation of position-by-position results in terms of time variance Example: assume water blockage similar to pedestrian blockage 2 inch step at 3 km/hr  61 ms per step 1024-octet packet at 110 Mbps  74 μs per packet ≤ 800 packets per 2 inch step at pedestrian speeds channel impulse response changes by anywhere from -20 dB (10% NRMSE) to 0 dB (100% NRMSE) over a duration ≤ 800 packets: as little as 0.013% NRMSE change per packet Steve Schell, Bitzmo Inc <author>, <company>

Other discussion of results <month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Other discussion of results Doppler spectrum cannot be estimated for this data set transition regions violate wide-sense-stationarity requirement stable WSS contain too little data Bandwidth dependencies when blockage is moving, results for 500 MHz and 2000 MHz channel bandwidths are similar situation changes when Tx or Rx is moving time-variant propagation distance causes prediction error to increase with increasing bandwidth simulated relative Tx-Rx motion at pedestrian speeds: results for 500 MHz bandwidth very similar to stationary case results for 2000 MHz bandwidth much worse (min error = 25%) Center-frequency dependencies prediction error (% NRMSE) increases mildly with f mean 25% at 3 GHz, increases to 40% at 8 GHz Steve Schell, Bitzmo Inc <author>, <company>

Recommendation PHY proposal evaluation include 2 scenarios <month year> doc.: IEEE 802.15-02/453r0-SG3a November 2002 Recommendation PHY proposal evaluation include 2 scenarios perfect packet-to-packet correlation channel impulse response constant across 100’s of packets example application scenario highest data-rate, short-range data transfers zero packet-to-packet correlation channels for consecutive packets are independent example application scenarios wireless HDTV / home theater with scampering kids run amok lower throughput connections (low packet rate) Steve Schell, Bitzmo Inc <author>, <company>