Location for 802.22 WRAN radio systems Presented to the IEEE - - PowerPoint PPT Presentation

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Location for 802.22 WRAN radio systems Presented to the IEEE - - PowerPoint PPT Presentation

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Doc: IEEE 22-06-0140-00-0000.odp July, 2006 Location for 802.22 WRAN radio systems Presented to the IEEE 802.22 by Ivan Reede TG4a Ivan Reede, AmeriSys Inc. Doc: IEEE 22-06-0140-00-0000.odp July, 2006 Location methods There are two

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SLIDE 1

Location for 802.22 WRAN radio systems

Presented to the IEEE 802.22 by Ivan Reede

July, 2006 TG4a Ivan Reede, AmeriSys Inc. Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 2

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

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 3

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) is converted to bearing – Requires known stable wave front

Source

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 4

Ranging

  • Difficult for low bandwidth (low speed) (MAC)
  • Well suited for higher bandwidth (fast) (PHY)
  • Requires simple logic addition (detector/counter)

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 5

Ranging Based Location Methods

  • Time Sum Of Arrival (TSOA)
  • Time Difference Of Arrival (TDOA)
  • Absolute Range

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 6

Location Method Requirements

  • TDOA and/or Direction Finding

– Requires minimal if any ranging abilities in CPEs – Requires at least two BS PHYs in cooperation to work – TDOA PHY array takes all readings at once – fastest result TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 7

Location Method Requirements

  • TSOA

– Requires more ranging abilities in CPEs and full ranging

abilites in BSs

– Requires at least two BSs in cooperation to work – Ill suited for currently single BS deployments TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 8

Location Method Requirements

  • Absolute

– Requires more ranging abilities in CPEs – Requires full ranging abilites in BSs – Requires only one BS to get some resolution – Works well with multiple BSs TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 9

Absolute Ranging Location

  • One range places source on the surface of a

sphere

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 10

Absolute Ranging Location

  • One range places source on the surface of a

sphere

  • Two intersecting spheres may place source on an

annular ring

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 11

Absolute Ranging Location

  • One range places source on the surface of a

sphere

  • Two intersecting spheres may place source on an

annular ring

  • Two intersecting annular rings may place source
  • n two points

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 12

Absolute Ranging Location

  • One range places source on the surface of a

sphere

  • Two intersecting spheres may place source on an

annular ring

  • Two intersecting annular rings may place source
  • n two points
  • Fourth range places source on a single point

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 13

Absolute Ranging Location

  • If we assume z=0 (forget altitude information)

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 14

Absolute Ranging Location

  • If we assume z=0 (forget altitude information)
  • One range places source on the surface of a ring

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 15

Absolute Ranging Location

  • If we assume z=0 (forget altitude information)
  • One range places source on an annular ring
  • Two intersecting rings may place source on any
  • f two points

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 16

Absolute Ranging Location

  • If we assume z=0 (forget altitude information)
  • One range places source on the surface of a circle
  • Two intersecting circles may place source on any
  • f 2 points
  • Third reading may place source on a single point

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 17

TSOA - I

  • TSOA is based on readings from two observers,

A and B at known locations. If the the sum of the time of arrival at A and B is known, D's position is constrained to be on the surface of an elipsoid

  • f revolution.

D A B

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 18
  • Two ranges places source on an ellipsoid of

revolution

  • Two intersecting ellipsiods of revolution may

place source on an annular ring

  • Two intersecting annular rings may place source
  • n two points
  • Another range may place source on one point
  • Some ranges may be replaced by geometrical

factors (such as assuming z=0)

TSOA - II

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 19

TDOA - I

  • TDOA is based on readings from two observers,

A and B at known locations. If the difference in the time of arrival at A and B is known, D's position is constrained to a hyperboloid of revolution.

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 20

TDOA - II

  • Two ranges places source on an hyperboloid of

revolution

  • Two intersecting hyperboloids of revolution may

place source on an annular ring

  • Another reading places source on two points
  • Another reading places source on one point
  • Some ranges may be replaced by geometrical

factors (such as assuming z=0)

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 21

TDOA Location - III

  • Graphically, the solution looks like:

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 22

Building a BS sensor array on the fly

  • Let's look at what's needed for a heterogenic BS

sensor array to self-construct in a plug & play map

  • To achieve this, we need to entertain the concept
  • f CPE time referential
  • Space has many dimensions

– X,Y,Z,Time,...

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 23

CPE Location and Ranging

BS A CPE F CPE E CPE D CPE B CPE C TfAB TfAC TfAD TfAE TfAF

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 24

CPE Location - I

  • Assume the BS PHYs are at known locations
  • CPEs have minimal location abilities

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 25

CPE Location - I

  • BS Transmits Ranging Query

– BS PHY records first high resolution time stamp

Ta BS time line CPE time line

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 26

CPE Location - II

  • CPE Receives Ranging Query

– CPE PHY records first high resolution time stamp

Ta TfAX Tx BS time line CPE time line

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 27

CPE Location - III

  • CPE Responds to Query with value Txr

– CPE PHY records second high resolution time stamp

Ta TfAX Txr BS time line BS time line

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 28

CPE Location - IV

  • BS Receives response to Query

– BS PHY records second high resolution time stamp

  • CPE transmits its time stamps to BS

Ta TfAX Txr TfXA Ta' BS time line CPE time line

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 29

RFD Location - V

  • In range BSs can report RFD TDOA data
  • Out of range BSs can report RFD TSOA data
  • CPE's don't need to keep track of absolute time

Ta TfAX Tx Txr Tx' TfXA Ta' BS A time line CPE time line

TfAX=(Ta'-Ta-Txr)/2

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 30

Proposal Conclusion

  • It may be very useful to include protocol

– To allow for time independent readings – To allow for TDOA and TSOA readings – To allow for simplified, rangeless CPEs

  • It may be useful to mandate a ranging packet data

pattern that forces a sharp leading edge pulse (6 Mhz BW) out of the FFT engine

  • This would make CPE ranging easier and more

precise (interpolating down to 5 meter resolution)

TG4a Ivan Reede, AmeriSys Inc. July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 31

3 Sensor TDOA Math I

TG4a Ivan Reede, AmeriSys Inc.

Assumptions

  • Let x,y,z be the position on the X and Y and Z axis of a flat

cartesian space

  • Position of sensors

– Sensor1, x1=0, y1=0, z1=0 (at the coordinate system origin) – Sensor2, x2=x2, y2=0, z2=0 (somwhere on the x axis) – Sensor3, x3=x3, y3=y3, z3=0 (somewhere on the x-y plane)

  • Position of source x0=xs, y0=ys, z0=zs
  • Distances can be computed from propagation delay

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 32

3 Sensor TDOA Math II

  • Let the propagation delay of a signal from the source to a sensor be

– D1 = delay from source to Sensor1 – D2 = delay from source to Sensor2 – D3 = delay from source to Sensor3

  • Let the TDOA from one sensor to another be

– D12 = D1 – D2 (TDOA between Sensor1 and Sensor2) – D13 = D1 – D3 (TDOA between Sensor1 and Sensor3)

  • Let the corresponding distances be

– R12 = R1 – R2 – R13 = R1 – R3

TG4a Ivan Reede, AmeriSys Inc.

Notations

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 33

3 Sensor TDOA Math III

TG4a Ivan Reede, AmeriSys Inc.

Assuming the source is located at x,y,z, geometry the

x2 y2 z2 x x2

2

y2 z2 R 12 x2 y2 z2 x x3

2

y y 3

2

z2 R 13

Starting Premise

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 34

3 Sensor TDOA Math IV

TG4a Ivan Reede, AmeriSys Inc.

Define an antenna baseline

L 3 x3

2

y 3

2

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 35

3 Sensor TDOA Math V

TG4a Ivan Reede, AmeriSys Inc.

After simplification

we obtain after simplification:

R 12

2

x2

2

2 x2

.

x

.

2 R 12

.

x2 y2 z2

.

R 13

2

L 3

2

2 x3

.

x

.

2 y 3

.

y

.

2 R 13

.

x2 y2 z2

.

These equations represent hyperboloids of revolution with foci at Sensors 1 and 2

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 36

3 Sensor TDOA Math VI

TG4a Ivan Reede, AmeriSys Inc.

Solution eliminate one degree of freedom by expressing y as a function of x

u R 13 R 12 x2

.

x3 y 3 v L 3

2

R 13

2

R 13 R 12

.

R 13 R 12 x2

2

.

2 y 3

.

y x ( ) u x

.

v

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 37

3 Sensor TDOA Math VII

TG4a Ivan Reede, AmeriSys Inc.

Solution eliminate a second degree of freedom by expressing z as a function of x

z x ( )2 d x2

.

e x

.

f d 1 x2 R 12

2

u2 e x2 1 x2 R 12

2

.

2 u

.

v

.

f R 12

2

4 1 x2 R 12

2 2

.

v2

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 38

3 Sensor TDOA Math VIII

TG4a Ivan Reede, AmeriSys Inc.

Solution eliminate a second degree of freedom by expressing z as a function of x

z x ( )2 d x2

.

e x

.

f

18.449 18.449 z plus x ( ) z minus x ( ) 2 1 x 1 0.75 0.5 0.25 0.25 0.5 0.75 1 1.25 1.5 1.75 2 20 10 10 20

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp

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SLIDE 39

3 Sensor TDOA Math VIX

TG4a Ivan Reede, AmeriSys Inc.

Solution If z is known, with the knowledge of the TDOA polarity, x is determined

z x ( )2 d x2

.

e x

.

f

xpos e e2 4 d

.

f

.

2 d

.

xneg e e2 4 d

.

f

.

2 d

.

For examples, with z=0, we have:

July, 2006 Doc: IEEE 22-06-0140-00-0000.odp