1. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: Ranging as a requirement for BAN and study on existing ranging schemes Date Submitted: May 12, 2008 Source: Giriraj Goyal, Kiran Bynam, Ranjeet Kumar Patro, Arun Naniyat, Seung-Hoon Park, Noh-Gyoung Kang, Jaeseung Son, EunTae Won Contact: Giriraj Goyal, giriraj.g@samsung.com, Samsung Electronicsgiriraj.g@samsung.com Voice: +91 80 41819999, E-Mail: giriraj.g@samsung.comgiriraj.g@samsung.com Re: [] Abstract: Brief overview of existing ranging techniques Purpose: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 May08 it would be made publicly available by P802.15.

2. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 2 Agenda Ranging applications Ranging as a Requirement criterion for BAN Existing Ranging and localization Techniques

3. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 3 Ranging applications GPS based application Radar applications Ship navigation Tracking search & rescue Inventory Security and surveillance

4. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 4 BAN Applications requiring Ranging Game application Body posture detection Tracking applications

5. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 5 Common Ranging Techniques Time-of-Arrival (TOA) –TOA/TWR –DTOA –TOA/OWR –TDOA Received signal strength (RSS) Angle-of-Arrival (AOA)

6. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 6 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.

7. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 7 Dev A Transmits signal Dev B receives the signal Dev B Respond back to dev A Dev A receives response from Dev B T OF T Response T OF T0T0 T1T1 time T OF = Time of flight for signal from Dev A to Dev B T Response = 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) Distance (between A and B) estimation done by A

8. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 8 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

9. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 9 Dev A Tx signal Dev B rx signal Dev B Respond back to dev A Dev A rx response from Dev B T OF T Response T OF T0T0 T1T1 time T OF = Time of flight for signal from Dev A to Dev B T Response = 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) T OF T Delay = 2*T Response T OF T0T0 T1T1 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 Random Time Delay

10. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 10 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 T OF T0T0 T1T1 Dev* B receives the signal Distance (between A and B) estimation done by B time T OF = Time of flight for signal from Dev A to Dev B * Device A and Device B are isochronous

11. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 11 Time Of Arrival (TOA) – 5 A1 Anchor1 (x1, y1) A3 Anchor3 (x1, y1) A2 Anchor2 (x1, y1) M Mobile Node (xm, ym) Anchors A1, A2 & A3 are centers of circles. Three circles will pass through one common point for a single solution. TOA Localization (circle geometry): 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

12. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 12 Mobile Node M Tx signal T OF 2 T0T0 T2T2 time Time Of Arrival (TOA) - 6 TDOA (Time Difference of Arrival) localization is a modification of TOA localization technique T OF 3 T OF 1 T3T3 T1T1 Mobile* Tx Anchor 2* Rx Anchor 3* Rx Anchor 1* Rx Reference time Anchor 2 Rx signal Anchor 1 Rx signal Anchor 2 sends T2 info to Anchor 1 Anchor 3 sends T3 info to Anchor 1 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

13. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 13 TDOA Localization (hyperbola geometry): Time Of Arrival (TOA) - 7 A1 Anchor1 (x1, y1) A2 Anchor2 (x1, y1) A3 Anchor3 (x1, y1) M Mobile Node (xm, ym) Anchors A1, A2 & A3 are Foci of Hyperbola Hyperbolas are drawn for locus of M with and as constant. Calculate Algorithm for drawing hyperbolic trajectory and finding point of intersection Estimate Note: 3 anchors with known positions (at least) are required to retrieve a 2D-position

14. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 14 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

15. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 15 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

16. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 16 Angle of Arrival (AOA) AOA could be an alternative solution to TOA/TDOA I.Lower requirements in terms of synchronization and clock precision II.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

17. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 17 Comparison chart Ranging TechniquesAdvantagesDisadvantages TOA Highly accurate for wide bands transmission as synchronization accuracy is high Clock drift issue Clock accuracy in nodes Clock synchronization is required RSS Less complexity Effected by channel dynamics AOALocalization 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

18. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 18 Ranging challenges MAC role/computation complexities Energy attenuation Multi-path channel Clock synchronization

19. May 2008 doc.: IEEE 802.15-08-0286-02-0006 Giriraj Goyal, Samsung Electronics Submission Slide 19 Reference 15-04-0581-07-004a-ranging- subcommittee-final-report.doc http://rfdesign.com/mag/radio_uwb_techno logy_locationaware/http://rfdesign.com/mag/radio_uwb_techno logy_locationaware/