July, 2002 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Propagation notes to P802.15 SG3a from IEEE Tutorial] Date Submitted: [17 July, 2002] Source: [Kai Siwiak] Company: [Time Domain Corporation] Address: [7057 Old Madison Pike, Huntsville, AL 35806] Voice: [256-990-9062] E-Mail: [ kai.siwiak@timedomain.com ] Re: [Response to the Call for Contributions on UWB Channel Models (IEEE P802.15-02/208r1-SG3a).] Abstract: [This contribution shows that a fundamental system gain limit in UWB places a constraint on maximum data rate versus bandwidth.] Purpose: [This contribution shows a fundamental system limit in UWB which is relevant to path loss and defines the fundamental limitations to range at a specific data rate in free space propagation. It is recommended that this fundamental limit be used to represent the performance of UWB systems instead of models representing tough RF environments which might be interpreted to conclude that UWB physical layer submissions for a high-rate extension to IEEE 802.15.3 would not work. The models need be concerned with selection criteria rather than with system design efforts. System designers will consider operating environments and other factors in designing and delivering robust implementations.] 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. Time Domain Corporation

UWB Propagation notes to P802.15 SG3a July, 2002 UWB Propagation notes to P802.15 SG3a A Fundamental System Gain Limit (Limit) for UWB can be defined in terms of: regulatory emission limits frequency band ideal modulation performance Implementations then degrade performance from this fundamental limit This limit provides a sanity check on UWB capabilities and should be used to describe the UWB median path loss for P802.15 SG3a activities. This propagation model along with multipath models being developed should then be used as selection criteria in SG3a Time Domain Corporation

UWB FCC Emission Limit for Hand-held Systems <month year> doc.: IEEE 802.15-<doc#> July, 2002 UWB FCC Emission Limit for Hand-held Systems 0.96 1.61 1.99 3.1 10.6 GPS Band Source: www.fcc.gov Time Domain Corporation <author>, <company>

Fundamental Limit: 173.3 dB/Hz System Gain <month year> doc.: IEEE 802.15-<doc#> July, 2002 Fundamental Limit: 173.3 dB/Hz System Gain -41.3 dBm/MHz -41.3 dBm / MHz +10 log(7.5x103) MHz -2.5 dBm EIRP 7,500 MHz -2.5 dBm EIRP -(-1.59) dB SNR -(-174.21) dBm/Hz . System Gain = 173.3 dBm/Hz -174.21 dBm/Hz -1.59 dB -1.59dB 3.1 GHz 10.6 GHz Bounded by FCC, Shannon, Boltzmann (thermal noise) Time Domain Corporation <author>, <company>

July, 2002 Limit and Parameters Limit means 1 b/s has available 173.3 dB path loss – nearly 2,000 km range between unity gain antennas! Practical implementations mean additional limits Desired data rates (much higher than 1 b/s!) EIRP further limited by FCC PSD masks corners, margin, and antenna implementations Practical modulations need further margin Noise figure and losses further limit performance Time Domain Corporation

Example: UWB at a High Data Rate <month year> doc.: IEEE 802.15-<doc#> July, 2002 Example: UWB at a High Data Rate Consider: 200 Mb/s system, Antipodal modulation: 10-3 BER, 9 dB noise figure + losses, 3.4-4.6 GHz, 0 dBi antennas System Gain 10 log(data bandwidth) SNR required by modulation System losses, (noise figure, implementation loss, ...) 10 log(“3dB” PSD BW / 7.5 GHz) Antenna gain or loss Path attenuation System Gain Limit 173.3 dB -10 log(200x106) = -83.0 dB -SNR= 6.8 - (- 1.59) = -8.4 dB -System losses = -9.0 dB 10 log(1.2 / 7.5) = -8.0 dB Antenna: = 0 dBi Left for Path attenuation: 64.9 dB 0.75 MAC and error correction factor brings link capacity to 150 Mb/s 1 m path loss = 44 dB, leaves 20+ dB for range: 10+ m in free space Time Domain Corporation <author>, <company>

Link Capacity vs. Range July, 2002 Limited by 2GHz bandwidth Fundamental limit with log2(1+S/N) in 3.1 to 10.6 GHz Fundamental limit 106 Example link, nominal path loss, 0.75 factor for MAC and error correction 105 104 103 Link Capacity, Mb/s 100 Example link, with 17dB additional loss 10 1 0.1 0.01 1 10 100 Nominal path loss from [4] 02/301r3 with d1=12 and g=3 Range, meters Time Domain Corporation

What limits UWB performance? July, 2002 System Gain Summary What limits UWB performance? Noise, bandwidth, emission limits, implementation efficiency What is the fundamental system gain limit? 173.3 dB/Hz How about a Practical limit? 173.3 – 8.4 – 9 – 8 »148 dB/Hz Time Domain Corporation

July, 2002 System Performance 200 Mb/s allows conservative error correction coding, ample MAC overhead for 110 Mb/s delivered at 10 m [2]: fits in 802.15.3 space and SG3a PAR [3] Noise figure and losses of 9 dB aggressive but realistic EIRP bandwidth respects 3.1 GHz 20 dB corner and UNII coexistence: again realistic Short range free space propagation between unity gain antennas assumed; seems justifiable as “total power” [4] propagation and in some LOS cases However, robust guaranteed-delivery system designs in the most difficult RF environments need as much as 17-20 dB more margin [5]!! Time Domain Corporation

July, 2002 Implications to 802.15 (SG3a) UWB Range limited by FCC masks and by practical implementations Propagation committee formed to study a channel model to realistically compare UWB solutions in multipath (and can provide important guidance to system designers) Practical 110 Mb/s at 10 m possible with realistic assumptions Additional margin is needed for robustness in the toughest and most demanding environments Implementers must consider operating environments and required performance in designing UWB solutions Time Domain Corporation

July, 2002 Conclusions Channel model (path loss + multipath) can serve many purposes Compare systems in a selection process Design robust guaranteed-performance systems Highlight especially challenging RF environments Robust guaranteed performance implies ~17 dB additional margin in tough RF environments – but lets not fix Guillotines! This margin is constant across systems Irrelevant to the SG3a selection criteria SG3a should follow the free space path loss model recommendation in [5] to 10 m, along with an accurate multipath component to depict system performance for selection process Time Domain Corporation

July, 2002 References [1] Kai Siwiak and Debra Culver, “UWB Radio Technology in Wireless PANs,” IEEE Vehicular Technology Conference, Birmingham, AL, May 6, 2002 [2] IEEEP802.15.(SG3a), “Technical Requirements Document,” 02104r10P802-15_SG3a-Technical-Requirements.doc, 17 June 2002 [3] IEEEP802.15.(SG3a), “IEEE P802.15.SG3a Alt-PHY Study Group PAR and 5 Criteria,” 02103r6P802-15_SG3a-PAR-5Criteria.doc, 24 June 2002 [4] K. Siwiak, “UWB Propagation Phenomena,” 02301r3P802-15_SG3a-UWB-Propagation-Phenomena.ppt, IEEEP802.15.(SG3a) document, July 2002 [5] Jeff Foerster, “SG3a Update of UWB Channel Modeling Sub-committee,” 02327r0P802-15_SG3a-Channel_model_update.ppt , IEEEP802.15. (SG3a) document, 11 July 2002 Time Domain Corporation