1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
September 10, 2004
Project: IEEE Study Group for Wireless Personal Area Networks (WPANs)
Submission Title: [On Sensitivity of Location Estimates to SNR]
Date Submitted: [10 September, 2004]
Source: [Shahriar Emami, Celestino A. Corral, Gregg Rasor]: Company1 [Freescale Semiconductor], Address [8000 W. Sunrise Blvd., Plantation, FL ], Voice:[(954) ], FAX: [(954) ], Re: [Accuracy of Location Estimates]
Abstract: [The relationship between SNR and location accuracy is explored. A region with reasonable location accuracy is found.]
Purpose: [To gain an understanding of parameters that impact location accuracy of TG4a. This work should assist designers in predicting the location accuracy of their system.]
Notice: This document has been prepared to assist the IEEE P 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 may be made publicly available by P
Shahriar Emami, Freescale Semiconductor
<author>, <company>

2. On Sensitivity of Location Estimates to SNR
September 10, 2004
On Sensitivity of Location Estimates to SNR
Shahriar Emami, Celestino A. Corral and Gregg Rasor
Freescale Semiconductor
Shahriar Emami, Freescale Semiconductor

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
September 10, 2004
Outline
Introduction
Prior Art
Open Issues
Proposed Approach
Root Raised Cosine (RRC) Pulse Shape
Raised Cosine (RC) Pulse Shape
Error Statistics & Achievable Accuracy
Conclusions
Shahriar Emami, Freescale Semiconductor
<author>, <company>

4. September 10, 2004
Introduction
The impact of AWGN on the accuracy of measurement was previously investigated:
- R. Enns, “The Effect of AWGN on Accuracy of Time of Arrival Detection,” IEEE a, July 2004.
Outstanding questions:
What is the desirable SNR in AWGN channels?
Does pulse shaping impact the location estimates?
Shahriar Emami, Freescale Semiconductor

5. Approach Pulse shapes - Root raised cosine - Raised cosine
September 10, 2004
Approach
Pulse shapes
- Root raised cosine
- Raised cosine
Various roll-off factors ( )
A length 31 PN sequence was utilized
Peak detector at the receiver
Shahriar Emami, Freescale Semiconductor

6. September 10, 2004
RRC Pulse Shape -1
Mean location estimate does not vary with roll-off factor
Shahriar Emami, Freescale Semiconductor

7. RRC Pulse Shape - 2 There are three distinct regions:
September 10, 2004
RRC Pulse Shape - 2
There are three distinct regions:
Shahriar Emami, Freescale Semiconductor

8. September 10, 2004
RRC Pulse Shape - 3
omni antenna above house
omni antenna near ground
Variance of the location estimate does not vary with roll-off factor
Shahriar Emami, Freescale Semiconductor

9. September 10, 2004
RC Pulse Shape - 1
Dry soil
Wet soil and wet roof
200 m
200 m
Mean location estimate does not vary with roll-off factor
Shahriar Emami, Freescale Semiconductor

10. September 10, 2004
RC Pulse Shape - 2
Dry soil
Wet soil
Variance of the location estimate does not vary with roll-off factor
Shahriar Emami, Freescale Semiconductor

11. September 10, 2004
Error Statistics
Dry soil
Dry soil
Mean and variance of estimation error when SNR = -5 dB
TX antenna placed at 1.5m height and at the side of the house
Shahriar Emami, Freescale Semiconductor

12. Achievable Location Accuracy
September 10, 2004
Achievable Location Accuracy
Consider a UWB
transmitter with:
- RRC pulse shaping
- Rc = 10 Mc/s
- 100 samples/chip
Sub meter accuracy with SNR>0 dB
Shahriar Emami, Freescale Semiconductor

13. September 10, 2004
Conclusions
There are three regions in terms of location estimate accuracy.
To have a good accuracy you need to operate in region 1.
Location accuracy appears to be independent of pulse shape and roll-off factor.
Sub-meter accuracy can be achieved if
SNR > 0 dB.
Shahriar Emami, Freescale Semiconductor