1. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Time-Domain-CFP-Response] Date Submitted: [4 January, 2005] Source: [Vern Brethour, Adrian Jennings] Company: [Time Domain Corp.] Address: [7057 Old Madison Pike; Suite 250; Huntsville, Alabama 35806] Voice: [Vern: (256) 428-6331; Adrian: (256) 428-6326], E-Mail: [vern.brethour@timedomain.com; adrian.jennings@timedomain.com] Re: [802.15.4a CFP] Abstract:[802.15.4a CFP response from Time Domain. An impulse radio nominally occupying 3 – 5 GHz with 4 ns chip times using 40 chips/symbol and 300 ns quiet time between symbols.] Purpose: [Response to WPAN-802.15.4a CFP] 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 individuals or organization. The material in this document is subject to change in form and content after further study. The contributors reserve the right to add, amend or withdraw material contained herein. Release:The contributors acknowledge and accept that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

2. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 2 Time Domain Proposal: Single Band UWB Alternate Physical Layer for TG 802.15.4a

3. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 3 Proposal Contents General Overview Proposal Principles Regulatory Flexibility Performance Evaluation Matrix (in backup slides)

4. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 4 General Overview Impulse radio Single band nominally from 3 to 5 Ghz. 4 ns chip times 40 chips per symbol 300 ns quiet time between symbols Max symbol integration = 64 (data) Max symbol integration = 256 (acquisition)

5. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 5 Proposal Principles The most important part of a proposal is the signal as it appears on the air. For most signal definitions, there are many ways to build a radio, and as many corresponding performance results. However, as a standard, we can define a signal which will forever limit the systems ultimate performance. (For example, by not using all reasonably available bandwidth.)

6. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 6 The need for robust links There is already a 15.4a radio at 2.54GHz. We must be substantially better than that radio. This proposal provides the opportunity for maximum performance by occupying as much bandwidth as reasonable.

7. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 7 Regulatory Flexibility There are fundamentally two approaches to UWB regulatory flexibility: –1) using multiple bands. –2) longer chip times. Using long chip times allows for filters if needed and does little harm if not needed.

8. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 8 Regulatory Flexibility This proposal occupies all of the spectrum between the ISM bands and the UNII bands This proposal allows ample (4 ns) chip time to accommodate spectral shaping if necessary. This proposal also allows a future (optional) band between 6 and 10 GHz.

9. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 9 Support for positioning There are already radios which do the low data rate communications job without positioning. Excellent positioning performance will be the key differentiator for 15.4a. Use of as much bandwidth as reasonable gives the best positioning performance.

10. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 10 What about the “simple radio” approach? Vocabulary is important here. Words like “simplicity” imply virtue. Words like “crude” and “unsophisticated” might be used by others to describe the same radio. The critical issue is that there will be other users of the spectrum and the 4a standard must use spectrum and air time efficiently and effectively. A proposed standard which we think implies a “simple and virtuous” radio might be viewed by others as spectrally wasteful and unworthy of letter ballot approval.

11. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 11 What does “simple radio” mean? A “simple radio” to our customers doing system integration, is a radio with the lowest chip count, the least number of passives and the most forgiving antenna driver. The integration customer does not (and should not) care how hard we have to work to implement the design inside of our chip.

12. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 12 Performance: the optimistic story. A “marketing style” link budget looks very optimistic. Even for 250 KByte/sec links, at 100 meters the link budget shows over 6dB of margin. ParameterValue Information Data Rate1 Kbps250 Kbps Average TX Power-12 dBm Total Path Loss84.5 dB (@ 100 meters) 84.5 dB (@ 100 meters) Average RX Power-96.5 dBm Noise Power Per Bit-144 dBm-120 dBm CMOS RX Noise Figure8 dB Total Noise Power-136 dBm-112 dBm Required Eb/N02.25 dB Implementation Loss6 dB Link Margin31.25dB7.25 dB RX Sensitivity Level-128 dBm-104. dBm Max. Range (AWGN)3652 m230 m

13. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 13 Link Performance: A realistic story. Performance predicted by the link budget is optimistic primarily due to the use of “2” for the path loss exponent. Links inside buildings with interior walls, will suffer path loss exponents more like “3”.

14. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 14 Link Performance A more realistic idea of performance is available by scaling the results of the simulations done for 802.15.3a to longer ranges and lower data rates. The 802.15.3a DS proposal uses signaling similar to this proposal, so I will scale from simulations reported in 802.15.04.0483r5 (McLaughlin, November 2004).

15. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 15 Scaling the DS results: The 3a DS radio is simulating an 11.8 meter link in CM4 at 110 Mbit/sec with a 90% packet success rate. Going from a link distance of 11.8 meters to 100 meters would seem to require less than 20 dB of additional processing gain. BUT that’s with a path loss exponent of 2. A path loss exponent of 3 requires 28 dB of processing gain.

16. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 16 How much integration is needed for 28 dB of processing gain? Each time we double the integration, we get another 3dB of processing gain. For 28 dB, we need to do 10 doublings, or an integration rate of 1024. Integration rate 1024 will take the 110 Mbit/sec rate down to 107 Kbit/sec.

17. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 17 Noticeable difference: Data ratePredicted range Link Budget with Path Loss exponent 2 250 Kbit/sec245 meters Scaled Simulation with Path Loss exponent 3 107 Kbit/sec118 meters

18. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 18 Even the Scaled Simulation is a very optimistic result: The DS radio that this prediction rests on is a very fancy radio: –16 Rake taps –31 tap decision feedback equalizer –Constraint length 6 convolutional code with Viturbi decoder –RF front end with 6.6 dB noise figure

19. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 19 Link budgets do not address acquisition. Acquisition will usually be the performance limiter at long range. The Acquisition decision needs an additional 6 dB of processing gain over data demodulation.

20. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 20 We must acquire without benefit of a trained equalizer. Equalizers are fine, but only after they have been trained. If the spacing between symbols is too short, the resulting inter symbol interference makes trouble for acquisition. This proposal uses a relatively long (300 ns) distance between symbols to handle large channel delay spreads without an equalizer.

21. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 21 Applications need robust links. The applications can stand low data rates, so this proposal uses data symbol integration of 64 and acquisition symbol integration 256. The long acquisition integration puts a burden on crystal tolerance (2 ppm) that not all vendors will want to deal with, so shorter integration modes will also be supported.

22. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 22 Clear Channel Assessment This is a hard problem for all UWB approaches. We should not ignore it. Detection of energy at the chipping rate (as in the 15.3a DS proposal) is doable, but not reliable. We may need relief from the MAC.

23. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 23 Simultaneously Operating Piconets The long symbol (40 chips) enables good orthagonality between piocnets. Different piconets use slightly different chipping rates like the 15.3a DS proposal. Bits are modulated onto symbols using only BPSK so all of the symbol orthogonality is used for piconet isolation.

24. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 24 Power control is the key to compatibility with 15.3a This proposal is set up for 100 meter links. Many applications will have shorter links. For shorter links, we turn down the Tx power. Power control gives superior compatibility with all services.

25. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 25 Proposal Summary Impulse radio Single band nominally from 3 to 5 Ghz. 4 ns chip times 40 chips per symbol 300 ns quiet time between symbols Max symbol integration = 64 (data) Max symbol integration = 256 (acquisition)

26. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 26 Backup Slides

27. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 27 Evaluation Matrix

28. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 28 Self Evaluation – General Solution Criteria CRITERIAEvaluation Unit Manufacturing Cost (UMC)+(no need for an equalizer) Signal RobustnessInterference+(due to power control) Signal RobustnessSusceptibility+(due to using max bandwidth) Coexistence+(due to power control) Technical FeasibilityManufacturability+(due to low peak Tx amplitudes) Time To Market+ Regulatory Impact+ (due to long chip times) Scalability+ Location Awareness+(due to using max bandwidth)

29. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 29 Self Evaluation – PHY Protocol Criteria CRITERIAEvaluation Size and Form Factor+ Payload Bit Rate+ Packet Overhead+ PHY-SAP Throughput+ Simultaneously Operation Piconets+(due to the long 40 chip symbol) Signal Acquisition+(due to long symbol integration) System Performance+ Link Budget+(due to using max bandwidth) Sensitivity+ Power Management Modes+ Power Consumption+ Antenna Practicality+

30. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 30 Example of a chip waveform

31. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 31 ………………………… 1233940 160 ns …………………………... Quiet time 4567838 Non-inverted pulses are blue, Nulled pulses are orange, Inverted pulses are green. Multiple chips make a symbol:

32. doc.: IEEE 802.15-05-0013-01-004a Submission January 2005 Vern Brethour, Adrian Jennings (Time Domain) Slide 32 Allow plenty quiet time between symbols 160 ns ……………………………………………. 300 ns