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 patcom@iee.org.>

Ivan Reede Montreal,CA 514-620-86522 i_reede@amerisys.com

October 2006

Ivan Reede Reede

Slide 2

doc.: IEEE 802.22-06/0206r0

Submission

Abstract

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

October 2006

Ivan Reede Reede

Slide 19

doc.: IEEE 802.22-06/0206r0

Submission

1

1

vp

10 p

sam ples

0 0 . 063 0 . 13 0 . 19 0 . 25 0 . 31 0 . 38 0 . 44 0 . 5 0 . 56 0 . 63 0 . 69 0 . 75 0 . 81 0 . 88 0 . 94 11

0

1B a s e b a n d t im e d o m a in s ig n a l

D A C ou tp u t sam p le #

OFDM System ExampleTransmitted 3 Khz Wave Symbol

October 2006

Ivan Reede Reede

Slide 20

doc.: IEEE 802.22-06/0206r0

Submission

A ±7.5° quantizationamounts to ±2.08 km

space-time uncertainty

OFDM System ExampleReceiver Space-Time Reference Frame

October 2006

Ivan Reede Reede

Slide 21

doc.: IEEE 802.22-06/0206r0

Submission

A ±7.5° quantizationamounts to a

100 km range ±2.08 kmspace-time frame

uncertainty

Rx

Tx

OFDM System ExampleReceiver 3 Khz wave Space-Time Reference Frame

October 2006

Ivan Reede Reede

Slide 22

doc.: IEEE 802.22-06/0206r0

Submission

A ±7.5° quantizationamounts to a

100 km range ±2.08 kmspace-time frame

uncertainty

Rx

Tx

Receiver 3KHz wave Space-time frame

OFDM System ExampleReceiver 3 Khz wave Space-Time Reference Frame Snapshot

October 2006

Ivan Reede Reede

Slide 23

doc.: IEEE 802.22-06/0206r0

Submission

• 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 50-100 km radius to a 1.04 km resolution

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 24

doc.: IEEE 802.22-06/0206r0

Submission

Transmitted 6 KHz wave symbol

1

1

vp

10 p

sam ples

0 0 . 063 0 . 13 0 . 19 0 . 25 0 . 31 0 . 38 0 . 44 0 . 5 0 . 56 0 . 63 0 . 69 0 . 75 0 . 81 0 . 88 0 . 94 11

0

1B a s e b a n d t im e d o m a in s ig n a l

D A C ou tp u t sam p le #

OFDM System ExampleTransmitted 6 Khz Wave Symbol

October 2006

Ivan Reede Reede

Slide 25

doc.: IEEE 802.22-06/0206r0

Submission

Rx

Tx

Receiver 3 and 6 Khz wave Space-time frame

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 26

doc.: IEEE 802.22-06/0206r0

Submission

A ±7.5° quantizationover 360° amounts to ±1.04 km resolutionover a 50 km range space-time frame

uncertainty

Rx

Tx

Receiver 6 Khz wave Space-time frame

The space-time framewraps twice through 360°

in a 100 km range

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 27

doc.: IEEE 802.22-06/0206r0

Submission

• Using both pilots, the OFDM 64-QAM receiver• May create a space-time frame

– With 1.04 km resolution– Within a 0-100 km radius

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 28

doc.: IEEE 802.22-06/0206r0

Submission

Transmitted 3 and 6 KHz waves symbol

1 .755

1 .755

vp

10 p

sam ples

0 0 .063 0 .13 0 .19 0 .25 0 .31 0 .38 0 .44 0 .5 0 .56 0 .63 0 .69 0 .75 0 .81 0 .88 0 .94 12

0

2B a s e b a n d t im e d o m a in s ig n a l

D A C ou tpu t sam p le #

OFDM System ExampleTransmitted 3 and 6 Khz Wave Symbol

October 2006

Ivan Reede Reede

Slide 29

doc.: IEEE 802.22-06/0206r0

Submission

Rx

Tx

Receiver 3 and 6 Khz wave Space-time frame

Using both wavesyields an unwrapped

2 km resolution100 km range

space-time frame

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 30

doc.: IEEE 802.22-06/0206r0

Submission

• 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 25-50 km radius– Within a 50-75 km radius– Within a 75-100 km radius

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 31

doc.: IEEE 802.22-06/0206r0

Submission

Transmitted 12 KHz wave symbol

1

1

vp

10 p

sam ples

0 0 . 063 0 . 13 0 . 19 0 . 25 0 . 31 0 . 38 0 . 44 0 . 5 0 . 56 0 . 63 0 . 69 0 . 75 0 . 81 0 . 88 0 . 94 11

0

1B a s e b a n d t im e d o m a in s ig n a l

D A C ou tp u t sam p le #

OFDM System ExampleTransmitted 12 Khz Wave Symbol

October 2006

Ivan Reede Reede

Slide 32

doc.: IEEE 802.22-06/0206r0

Submission

Transmitted 3 and 6 and 12 KHz wave symbol

2 .227

2 .227

vp

10 p

sam ples

0 0 .063 0 .13 0 .19 0 .25 0 .31 0 .38 0 .44 0 .5 0 .56 0 .63 0 .69 0 .75 0 .81 0 .88 0 .94 14

2

0

2

4B a s e b a n d t im e d o m a in s ig n a l

D A C ou tpu t sam p le #

OFDM System ExampleTransmitted 3 and 6 and 12 Khz Wave Symbol

October 2006

Ivan Reede Reede

Slide 33

doc.: IEEE 802.22-06/0206r0

Submission

Rx

Tx

Receiver 3 and 6 and 12 Khz wave Space-time frame

Using all 3 wavesyields an unwrapped0.52 km resolution

100 km rangespace-time frame

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 34

doc.: IEEE 802.22-06/0206r0

Submission

• With more pilot's, as follows

3000 100000 2083.33 5277.78 125006000 50000 1041.67 2638.89 6250

12000 25000 520.83 1319.44 312524000 12500 260.42 659.72 1562.548000 6250 130.21 329.86 781.2596000 3125 65.1 164.93 390.63192000 1562.5 32.55 82.47 195.31384000 781.25 16.28 41.23 97.66768000 390.63 8.14 20.62 48.83

1536000 195.31 4.07 10.31 24.413072000 97.66 2.03 5.15 12.215997000 50.03 1.04 2.64 6.25

Pilot Baseband Frequency (Hz)

Wavelength range (m)

'±7.5° rangeresolution (m)

'±19° rangeresolution (m)

'±45° rangeresolution (m)

OFDM System Example(cont.)

October 2006

Ivan Reede Reede

Slide 35

doc.: IEEE 802.22-06/0206r0

Submission

Transmitted 12 pilot wave symbol

6 .411

6 .411

vp

10 p

sam ples

0 0 .063 0 .13 0 .19 0 .25 0 .31 0 .38 0 .44 0 .5 0 .56 0 .63 0 .69 0 .75 0 .81 0 .88 0 .94 110

5

0

5

10B a s e b a n d t im e d o m a in s ig n a l

D A C ou tpu t sam p le #

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