may 2008 doc.: ieee 802.15-08-0286-02-0006 giriraj goyal, samsung electronics submission slide 1...

May 2008 doc.: IEEE 802.15-08-0286-02-0006

Giriraj Goyal, Samsung ElectronicsSlide 1Submission

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)(WPANs)

Submission Title: Ranging as a requirement for BAN and study on existing ranging schemes

Date Submitted: May 12, 2008Source: Giriraj Goyal, Kiran Bynam, Ranjeet Kumar Patro, Arun Naniyat, Seung-Hoon Park,

Noh-Gyoung Kang, Jaeseung Son, EunTae WonContact: Giriraj Goyal, [email protected], Samsung ElectronicsVoice: +91 80 41819999, E-Mail: [email protected]: []Abstract: Brief overview of existing ranging techniquesPurpose: To identify ranging as a requirement for BAN applications set and present brief

study on existing ranging mechanisms.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'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 acknowledges and accepts that this contribution becomes the property of IEEE and in May’08 it would be made publicly available by P802.15.

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Agenda

• Ranging applications

• Ranging as a Requirement criterion for BAN

• Existing Ranging and localization Techniques

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Ranging applications

• GPS based application

• Radar applications

• Ship navigation

• Tracking ‘search & rescue’

• Inventory

• Security and surveillance

May 2008 doc.: IEEE 802.15-08-0286-02-0006


BAN Applications requiring Ranging

• Game application

• Body posture detection

• Tracking applications

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Common Ranging Techniques

• Time-of-Arrival (TOA)– TOA/TWR– DTOA– TOA/OWR– TDOA

• Received signal strength (RSS)

• Angle-of-Arrival (AOA)

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Assumptions with ranging techniques

• Direct line of sight

• Static channel condition

• Anchor (reference) nodes and the nodes are static when distances are measured.

• Anchor nodes positions are known to each other.

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Dev A Transmits signal

Dev B receives the signal

Dev B Respond back to dev A Dev A receives response from Dev B

TOF TResponse TOF

T0 T1

time

• TOF = Time of flight for signal from Dev A to Dev B• TResponse = Turnaround time for Dev B to respond back to Dev A (Prescribed Protocol Delay and/or

Processing Time)

Time Of Arrival (TOA) – 1• TOA/TWR – Two way ranging (Single packet exchange)

c.T

~d~

TTT2

1T~

OFAB

01AOF

ReplyDistance (between A and B) estimation done by A

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Time of Arrival (TOA) - 2

Range estimation with TOA/TWR is affected by :– Relative clock drift between A and B

– Clock accuracy in A and B

– Prescribed response delay

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Dev A Tx signal

Dev B rx signal

Dev B Respond back to dev A

Dev A rx response from Dev B

TOF TResponse TOF

T0 T1

time

• TOF = Time of flight for signal from Dev A to Dev B• TResponse = Turnaround time for Dev B to respond back to Dev A (Prescribed Protocol Delay and/or

Processing Time)

Time Of Arrival (TOA) – 3• TWR with Double packet exchange; known as DTOA (Differential Time of Arrival)• DTOA is a modification of TOA/TWR technique, to remove effects of

protocol/response delay (turn around time)

TOF TDelay = 2*TResponse TOF

T’0 T’1

Dev A Tx signal

Dev B rx signal

Dev B Respond back to dev A

Dev A rx response from Dev B

Distance (between A and B) estimation done by A c.T

~d~

}2/)'T'T{()TT(T

OFAB

0101OF

Random Time Delay

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Time Of Arrival (TOA) - 4• OWR – One way ranging, If Terminals are synchronized to a common

clock, direct OWR can be used.

Dev A* Transmits signal

TOF

T0 T1

Dev* B receives the signal

Distance (between A and B) estimation done by B

c.T

~d~

TTT~

BOFAB

01BOF

time

• TOF = Time of flight for signal from Dev A to Dev B• * Device A and Device B are isochronous

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Time Of Arrival (TOA) – 5

2d

3d

A1Anchor1 (x1, y1)

A3Anchor3 (x1, y1)

A2Anchor2 (x1, y1)

MMobile Node (xm, ym)

1d

•Anchors A1, A2 & A3 are centers of circles.•Three circles will pass through one common point for a single solution.

TOA Localization (circle geometry):

1312

~~d,d

MM yx ~,~

Calculate

Algorithm for drawing circle trajectory and finding common point of intersection

Estimation

• 3 anchors with known positions (at least) are required to retrieve a 2D-position

• 4 anchors with known positions (at least) are required to retrieve a 3D-position

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Mobile Node M Tx signal

TOF 2

T0

T2

time

Time Of Arrival (TOA) - 6• TDOA (Time Difference of Arrival) localization is a modification of TOA

localization technique

TOF 3

TOF 1

T3

T1

Mobile* Tx

Anchor 2* Rx

Anchor 3* Rx

Anchor 1* Rx

Reference time

Anchor 2 Rx signal

Anchor 2 Rx signal

Anchor 1 Rx signal

Anchor 2 sends T2 info to Anchor 1

Anchor 3 sends T3 info to Anchor 1

cTdTTT

cTdTTT

.~~~

.~~~

23233113

21212112

• Time of flight information by anchor nodes can be calculated by any of TOA method.

• Example shows Time Difference by a anchor node (anchor 1) can be calculated by any reference time if TOA/OWR ranging method

TDOA Estimation

May 2008 doc.: IEEE 802.15-08-0286-02-0006


TDOA Localization (hyperbola geometry):

Time Of Arrival (TOA) - 7

1312

~~d,d

MM yx ~,~1d

3113 ddd

2112 ddd

)( 21 MAMA

A1Anchor1 (x1, y1)

A2Anchor2 (x1, y1)

A3Anchor3 (x1, y1)

MMobile Node (xm, ym)

•Anchors A1, A2 & A3 are Foci of Hyperbola•Hyperbolas are drawn for locus of M with and as constant.)( 31 MAMA

Calculate

Algorithm for drawing hyperbolic trajectory and finding point of intersection

Estimate

2d

3d

Note: 3 anchors with known positions (at least) are required to retrieve a 2D-position

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Received Signal Strength (RSS) – 1

-Devices calculate ranges to their neighbors-Location is jointly estimated using collective information-Location Accuracy/ Range Extension

Processing unit

Data link

Anchor/reference node

Nodes required being located

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Received Signal Strength (RSS) – 2

• RSS is an alternative solution to TOA/TDOA as it lowers requirements in terms of synchronization and clock precision

The Disadvantages are –•RSSI requires precise channel behavioral model•This technique is sensitive to channel inconsistency

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Angle of Arrival (AOA)

AOA could be an alternative solution to TOA/TDOAI. Lower requirements in terms of synchronization and clock

precisionII. Two anchors are sufficient for 2D-positioning and three for 3D-

positioning

•AOA requires precise calibration at anchor nodes•Cost increases with size and size may not be reduced

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Comparison chart Ranging Techniques Advantages Disadvantages

TOAHighly accurate for wide bands transmission as synchronization accuracy is high

•Clock drift issue•Clock accuracy in nodes •Clock synchronization is required

RSSLess complexity Effected by channel dynamics

AOA •Localization technique•Number of anchors required for 2-D and 3-D positioning are lesser than TOA technique.

•Multi-path effects changes phase of a signal and can yield large positioning errors.•Requires array of antenna

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Ranging challenges

• MAC role/computation complexities

• Energy attenuation

• Multi-path channel

• Clock synchronization

May 2008 doc.: IEEE 802.15-08-0286-02-0006


Reference• 15-04-0581-07-004a-ranging-

subcommittee-final-report.doc

• http://rfdesign.com/mag/radio_uwb_technology_locationaware/

may 2008 doc.: ieee 802.15-08-0286-02-0006 giriraj goyal, samsung electronics submission slide 1...

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