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Doc.: IEEE 802.22-06/0206r0 Submission October 2006 Ivan Reede Reede Slide 1 Ranging and Location for 802.22 WRANs IEEE P802.22 Wireless RANs Date: 2006-10-10.

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Presentation on theme: "Doc.: IEEE 802.22-06/0206r0 Submission October 2006 Ivan Reede Reede Slide 1 Ranging and Location for 802.22 WRANs IEEE P802.22 Wireless RANs Date: 2006-10-10."— Presentation transcript:

1 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 1 Ranging and Location for WRANs IEEE P Wireless RANs Date: Authors: Notice: This document has been prepared to assist IEEE 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at > Ivan Reede Montreal,CA

2 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 2 Abstract A means to range links from base stations to customer premise equipment inter customer premise equipments distances inter base stations distances Means to apply obtained results to establish the geographic location of these devices

3 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 3 Location methods There are two basic data acquisition methods –Direction Finding –Ranging Both can be used together to determine a location from another location Both can be used without the other to determine a location from a group of other locations

4 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 4 Direction Finding Conventionally performed by CW systems –CW time difference of arrival at the sensors –Results obtained from difference in time of arrival –Time difference (phase) between arials is converted to bearing –Requires known stable wave front Source Arial 1 Arial 2

5 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 5 Ranging Difficult for some legacy PHY layers Difficult for some legacy MAC layers Well suited for higher bandwidth (fast) (PHY)

6 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 6 Ranging over OFDM Well suited for PHY layer May be supported by MAC layer Requires a conceptually simple addition

7 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 7 OFDM receivers inherently effect range bearing information collection in normal operations Such information is required for their operation Such information has not yet been recognized in any public documentation as range bearing In a 6 MHz BW channel, 1 meter ranging resolution may be achieved By the following means... OFDM System Example Assertion Overview

8 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 8 OFDM System Example Founding Premises OFDM systems transmit using a plurality of carriers These carriers are at slightly different frequencies at RF, but are harmonically related at baseband They are related by the fact that they are all transmitted simultaneously in a package called an OFDM symbol

9 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 9 The source of the OFDM symbol is usually an IFFT device The symbol output is generally composed of a sum of sine and cosine waves All of these sine and cosine waves –Start at the beginning of each symbol –End at the end of each symbol –Sine waves begin and end with zero values –Cosine waves begin and end with full amplitude values at symbol edges OFDM System Example Model Overview

10 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 10 The receiver is generally composed of an FFT device This device acts as a multi-carrier QPSK or n-QAM demodulator Each carrier can be demodulated as QPSK, 16-QAM, 64-QAM or other As such, the OFDM receiver extracts amplitude and phase information from each carrier OFDM System Example Model Overview

11 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 11 Current receiver designs use pilot carriers to align the constellation demodulation process Assume, by standardization –That a pilot carrier be emitted with a known phase The receiver, in aligning to this carrier, essentially effects a “phase lock” to this pilot It demodulates with a known phase resolution –~±45° for QPSK, ~±7.5° for 64-QAM OFDM System Example Model Overview

12 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 12 To demodulate QPSK phase lock must be much better than ±45° OFDM System Example QPSK Constellation

13 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 13 To demodulate 16-QAM phase lock must be much better than ±19° OFDM System Example 16-QAM Constellation

14 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 14 To demodulate 64-QAM phase lock must be much better than ±7.5° OFDM System Example 64-QAM Constellation

15 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 15 Transmitters internally use at least one clock The symbols they transmit are related to this clock By transmitting an OFDM symbol, they inherently broadcast their space-time reference frame, relative to their geolocation and their clock OFDM System Example Transmitter Space-Time Reference Frame

16 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 16 Tx Symbols emanating from the transmitter Transmitted wave conveys the Tx's Space-time frame OFDM System Example Transmitter Space-Time Reference Frame

17 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 17 If the receiver knew exactly at what time the symbol was sent by the transmitter, the receiver could determine the distance from the flight time The receiver lacks this knowledge The receiver, however, can lock an internal time base (i.e. a counter) to the received wave The receiver can therefore create a relative space-time frame from a received OFDM symbol OFDM System Example Receiver Premises

18 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 18 Assume a transmitter emits an OFDM symbol that contains a pilot carrier whose frequency is 3 KHz The wavelength associated with this frequency is ~100 km. A 64-QAM receiver, can lock its time base to this pilot within ±7.5° This creates a receiver relative space-time frame –in a km radius to a 2.08 km resolution OFDM System Example Fundamental Operating Principles

19 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 19 OFDM System Example Transmitted 3 Khz Wave Symbol

20 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 20 A ±7.5° quantization amounts to ±2.08 km space-time uncertainty OFDM System Example Receiver Space-Time Reference Frame

21 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 21 A ±7.5° quantization amounts to a 100 km range ±2.08 km space-time frame uncertainty Rx Tx OFDM System Example Receiver 3 Khz wave Space-Time Reference Frame

22 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 22 A ±7.5° quantization amounts to a 100 km range ±2.08 km space-time frame uncertainty Rx Tx Receiver 3KHz wave Space-time frame OFDM System Example Receiver 3 Khz wave Space-Time Reference Frame Snapshot

23 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 23 Assume the transmitter emits an OFDM symbol that contains a pilot carrier whose frequency is 6 KHz The wavelength associated with this frequency is ~50 km. A 64-QAM receiver, can lock its time base to this pilot within ±7.5° This creates a wrapped relative space-time frame –in a 0-50 km radius to a 1.04 km resolution –in a km radius to a 1.04 km resolution OFDM System Example (cont.)

24 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 24 Transmitted 6 KHz wave symbol OFDM System Example Transmitted 6 Khz Wave Symbol

25 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 25 Rx Tx Receiver 3 and 6 Khz wave Space-time frame OFDM System Example (cont.)

26 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 26 A ±7.5° quantization over 360° amounts to ±1.04 km resolution over a 50 km range space-time frame uncertainty Rx Tx Receiver 6 Khz wave Space-time frame The space-time frame wraps twice through 360° in a 100 km range OFDM System Example (cont.)

27 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 27 Using both pilots, the OFDM 64-QAM receiver May create a space-time frame –With 1.04 km resolution –Within a km radius OFDM System Example (cont.)

28 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 28 Transmitted 3 and 6 KHz waves symbol OFDM System Example Transmitted 3 and 6 Khz Wave Symbol

29 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 29 Rx Tx Receiver 3 and 6 Khz wave Space-time frame Using both waves yields an unwrapped 2 km resolution 100 km range space-time frame OFDM System Example (cont.)

30 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 30 Assume the transmitter emits an OFDM symbol that contains a pilot carrier whose frequency is 12 KHz A 64-QAM receiver, can lock its time base to this pilot within ±7.5° Using these pilots, the OFDM 64-QAM receiver May create a space-time frame –With 0.52 km resolution –Within a 0-25 km radius –Within a km radius –Within a km radius –Within a km radius OFDM System Example (cont.)

31 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 31 Transmitted 12 KHz wave symbol OFDM System Example Transmitted 12 Khz Wave Symbol

32 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 32 Transmitted 3 and 6 and 12 KHz wave symbol OFDM System Example Transmitted 3 and 6 and 12 Khz Wave Symbol

33 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 33 Rx Tx Receiver 3 and 6 and 12 Khz wave Space-time frame Using all 3 waves yields an unwrapped 0.52 km resolution 100 km range space-time frame OFDM System Example (cont.)

34 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 34 With more pilot's, as follows OFDM System Example (cont.)

35 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 35 Transmitted 12 pilot wave symbol OFDM System Example Transmitted 12 Pilot Example Wave Symbol

36 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 36 Using multiple pilots, the OFDM 64-QAM receiver May create a space-time frame –With 1 m resolution –Within a km radius It still does not know the transmitter to receiver distance It knows the space-time frame of the signal It may lock its time base to that space-time frame OFDM System Example (cont.)

37 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 37 The receiving station can respond to queries, in a manner synchronous to the center of this space-time frame. The initial transmitter, when it receives a response from the station, can also establish a similar space time frame The discrepancy between the transmitter's initial space-time frame and the responses space-time frame reveals the total flight time Taking into account that the receiver is able to receive 12 dB SNR signals, the phase lock of real receiver must be much better and the total travel time can be estimated to within ~±0.5m resolution OFDM System Example (cont.)

38 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 38 Other stations, hearing query responses, may also perceive and measure space-time frame discrepancies. These discrepancies reveal flight times, within ~±0.5 m resolution A collectivity of stations can accumulate a wealth of space-time frame discrepancies Once collected and processed, this information reveals precise station location and channel characteristics OFDM System Example (cont.)

39 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 39 Ranging Based Location Methods Time Sum Of Arrival (TSOA) Time Difference Of Arrival (TDOA) Absolute Range For more details see July 2006 presentation

40 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 40 Ranging Based Location Methods Geolocation Ranging Web Possibilities BS CPE4 CPE3 CPE2 CPE1 CPE5 Range web values may reveal elevation info / coax-lead-line length Z

41 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 41 OFDM Ranging Summary Costs Requires minimal if any ranging abilities in CPEs Requires at least three located waypoints, at the BS or CPE or some other known terrain characteristics Economical –it better exploits existing OFDM hardware –the pilot tones are already there for constellation sync –no special ranging symbols, symbols may be data bearing –practically no overhead –less overhead than any other location method –no external costs (such as GPS system costs + intsalltaion) Does not require many added abilities out of the CPE

42 doc.: IEEE /0206r0 Submission October 2006 Ivan Reede Reede Slide 42 OFDM Ranging Summary Benefits Simple, the pilot tones are already there for constellation sync Fast and precise results, from a single query-response –Provides the required resolution –Provides enough resolution for 3d location, including feed lines –Provides support for fixed devices –Provides support for mobility detection and tracking Is amenable to processing gain means on range and precision Is self supportive, does not require external technology assists Provides the ranging information needed to geolocate devices in a simple, economical, elegant, inband and transparent fashion


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