October 2006 Ivan Reede Reede Slide 1 doc.: IEEE 802.22-06/0206r0 Submission Ranging and Location for 802.22 WRANs IEEE P802.22 Wireless RANs Date: 2006-10-10 N am e C om pany A ddress Phone em ail Authors: Notice: This document has been prepared to assist IEEE 802.22. 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 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf 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 Chair Carl 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected]. Ivan Reede Montreal,CA 514-620-86522 [email protected]
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October 2006
Ivan Reede Reede
Slide 1
doc.: IEEE 802.22-06/0206r0
Submission
Ranging and Location for 802.22 WRANsIEEE P802.22 Wireless RANs Date: 2006-10-10
Name Company Address Phone email
Authors:
Notice: This document has been prepared to assist IEEE 802.22. 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 802.22.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf 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 Chair Carl 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].>
A means to range802.22 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
October 2006
Ivan Reede Reede
Slide 3
doc.: IEEE 802.22-06/0206r0
Submission
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
October 2006
Ivan Reede Reede
Slide 4
doc.: IEEE 802.22-06/0206r0
Submission
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
October 2006
Ivan Reede Reede
Slide 5
doc.: IEEE 802.22-06/0206r0
Submission
Ranging
• Difficult for some legacy PHY layers• Difficult for some legacy MAC layers• Well suited for higher bandwidth (fast) (PHY)
October 2006
Ivan Reede Reede
Slide 6
doc.: IEEE 802.22-06/0206r0
Submission
Ranging over OFDM
• Well suited for PHY layer• May be supported by MAC layer• Requires a conceptually simple addition
October 2006
Ivan Reede Reede
Slide 7
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleAssertion Overview
October 2006
Ivan Reede Reede
Slide 8
doc.: IEEE 802.22-06/0206r0
Submission
OFDM System ExampleFounding 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
October 2006
Ivan Reede Reede
Slide 9
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleModel Overview
October 2006
Ivan Reede Reede
Slide 10
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleModel Overview
October 2006
Ivan Reede Reede
Slide 11
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleModel Overview
October 2006
Ivan Reede Reede
Slide 12
doc.: IEEE 802.22-06/0206r0
Submission
To demodulate QPSKphase lock must be
much better than ±45°
OFDM System ExampleQPSK Constellation
October 2006
Ivan Reede Reede
Slide 13
doc.: IEEE 802.22-06/0206r0
Submission
To demodulate 16-QAMphase lock must be
much better than ±19°
OFDM System Example16-QAM Constellation
October 2006
Ivan Reede Reede
Slide 14
doc.: IEEE 802.22-06/0206r0
Submission
To demodulate 64-QAMphase lock must be
much better than ±7.5°
OFDM System Example64-QAM Constellation
October 2006
Ivan Reede Reede
Slide 15
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleTransmitter Space-Time Reference Frame
October 2006
Ivan Reede Reede
Slide 16
doc.: IEEE 802.22-06/0206r0
Submission
Tx
Symbols emanatingfrom the transmitter
Transmitted wave conveys the Tx's Space-time frame
OFDM System ExampleTransmitter Space-Time Reference Frame
October 2006
Ivan Reede Reede
Slide 17
doc.: IEEE 802.22-06/0206r0
Submission
• 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 ExampleReceiver Premises
October 2006
Ivan Reede Reede
Slide 18
doc.: IEEE 802.22-06/0206r0
Submission
• 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 0-100 km radius to a 2.08 km resolution
OFDM System ExampleFundamental Operating Principles
OFDM System ExampleTransmitted 12 Pilot Example Wave Symbol
October 2006
Ivan Reede Reede
Slide 36
doc.: IEEE 802.22-06/0206r0
Submission
• Using multiple pilots, the OFDM 64-QAM receiver• May create a space-time frame
– With 1 m resolution– Within a 0-100 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.)
October 2006
Ivan Reede Reede
Slide 37
doc.: IEEE 802.22-06/0206r0
Submission
• 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.)
October 2006
Ivan Reede Reede
Slide 38
doc.: IEEE 802.22-06/0206r0
Submission
• 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.)
October 2006
Ivan Reede Reede
Slide 39
doc.: IEEE 802.22-06/0206r0
Submission
Ranging Based Location Methods
• Time Sum Of Arrival (TSOA)• Time Difference Of Arrival (TDOA)• Absolute Range
For more details seeJuly 2006 presentation
October 2006
Ivan Reede Reede
Slide 40
doc.: IEEE 802.22-06/0206r0
Submission
Ranging Based Location MethodsGeolocation Ranging Web Possibilities
BS
CPE4
CPE3
CPE2CPE1
CPE5
Range web valuesmay reveal elevationinfo / coax-lead-line
length
Z
October 2006
Ivan Reede Reede
Slide 41
doc.: IEEE 802.22-06/0206r0
Submission
OFDM Ranging SummaryCosts
• 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
October 2006
Ivan Reede Reede
Slide 42
doc.: IEEE 802.22-06/0206r0
Submission
OFDM Ranging SummaryBenefits
• 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