UWB System Design for Low Power, Precision Location

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title: [UWB System Design for Low Power, Precision Location TG4a] Date Submitted: [March 2004] Source: [Roberto Aiello] Company [Staccato Communications] E-mail [Roberto@StaccatoCommunications.com] Re: [Design Considerations for UWB low rate] Abstract: [This presentation introduces some fundamental concepts for UWB system design in preparation for evaluation of forthcoming PHY proposals] Purpose: [In anticipation of CFP for 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 or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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.

2. UWB System Design Considerations for Low Power + Precision Location Roberto Aiello Roberto@StaccatoCommunications.com Staccato Communications Roberto Aiello, Staccato Communications

3. Summary • Applications of low power & location awareness • Requirements • Low duty cycle – long battery life • Precision ranging – methods of location estimation • Other relevant parameters Roberto Aiello, Staccato Communications

4. Application examples • Building automation (ease of installation and maintenance) • Home automation • Inventory (hospital, warehouses, file tracking, etc.) • People tracking (resource optimization in offices), optimize efficiency/security in factories, etc.) Roberto Aiello, Staccato Communications

5. Location relevant requirements • No mobility or low speed requirement • Relatively fast response time for tracking • Centimeters to meters resolution and accuracy • Low power (long battery lifetime) • Low cost Roberto Aiello, Staccato Communications

6. Methods for location awareness • Fixed infrastructure • Access points synchronization • Inverse GPS triangulation • Ad hoc network • No engineered access points • Only relative distances between nodes are known • Ad hoc network with fixed references • Some network nodes fix location and provide reference • 2 references to fix in 2D, 3 references to fix in 3D Roberto Aiello, Staccato Communications

7. UWB advantages • High accuracy (proportional to bandwidth) • Robust to multipath and to interference • Low power consumption • Leads to low cost implementation Roberto Aiello, Staccato Communications

8. Battery characteristics Source: doc.: IEEE 802.15-01/231r2 Roberto Aiello, Staccato Communications

9. Power sources’ characteristics • 100mW is the threshold for energy scavenging Roberto Aiello, Staccato Communications

10. Practical means of energy scavenging Roberto Aiello, Staccato Communications

11. Example UWB link budget • Negative RX antenna gain • 500 MHz bandwidth • 2 MHz chip rate (10 chips/bit) • 200 kbps raw bit rate, ½ coding • 30 dB link margin at 10m • 300 m path loss d = 2 • 30 m path loss d = 3.5 Roberto Aiello, Staccato Communications

12. Radio transmitter • Minimum UWB bandwidth allowed: 500 MHz • UWB transmit power • PSD = -41.3 dBm/MHz • Average power: -14.3dBm => 38 mW • Energy/bit (@100 kbps) = 0.38 nJ/bit Roberto Aiello, Staccato Communications

13. Radio receiver • Analog section power typically dominated by oscillators and mixers • Digital section power driven by clock rate • Low power UWB radio: not a software radio! • Analog section • No LNA: increase transmit power, allow higher noise figure • No oscillator at the receiver: envelope detector • Low power oscillator: low Q and relaxed phase noise requirement, low power reference oscillator • Digital section • Circuits running at symbol rate (kHz or MHz), not at RF rate (GHz) • Design compromise for very low power optimization will impact performance optimization Roberto Aiello, Staccato Communications

14. Transceiver architecture • Fast wake-up • 1ms acquisition time => 6.2mJ per first bit acquired • Transmit/receive accurate synchronization • Requires correct system architecture • Adaptive periodic polling (application dependent) Receiver power budget Roberto Aiello, Staccato Communications

15. Other issues relevant to TG4 • Communication and location may not require processing different paths, but different clock resolution • Communication and location are probably separate functions • Most of location function is PHY related -> no MAC modifications required Roberto Aiello, Staccato Communications

16. Conclusions • UWB is a natural technology for location awareness • Provides additional feature beyond a “communications only” platform • UWB works in multipath environments where narrow band approaches are challenged Roberto Aiello, Staccato Communications

17. References • UWB: a solution for location awareness in TG4 applications • 03050r1P802-15_TG4-UWB-a-solution-for-location-awareness • Understanding UWB - Principles & Implications for Low-Power Communications • 03157r1P802-15_WG-Understanding_UWB_For_Low-Power_Communications-A_Tutorial Roberto Aiello, Staccato Communications