March 2004

Communications Research Laboratory Slide 1

doc.: IEEE802.15-04-0111-00-004a

Submission

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

Submission Title: [Path-Loss Exponents of Ultra Wideband Signals in Line-of-Sight Environments]Date Submitted: [14 March, 2004]Source: [Shunsuke Sato and Takehiko Kobayashi]Company [UWB Technology Institute, Communications Research Laboratory / Tokyo Denki

University]Address [Tokyo Denki University, 2-2 Kanda-nishiki-cho, Chiyoda-ku, Tokyo 101-8457, Japan]Voice [+81 3 5280 3839]E-Mail: [shunsuke@grace.c.dendai.ac.jp, koba@c.dendai.ac.jp]Re: [Status report of the 802.15.4a channel modeling subgroup]Abstract: [This contribution describes a new line-of-sight path loss formula for ultra wideband signals in the presence of the ground plane reflection.]Purpose: [Reports on a UWB pass loss formula for IEEE802.15TG4a]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 may be made publicly available by P802.15.

March 2004

Communications Research Laboratory Slide 2

doc.: IEEE802.15-04-0111-00-004a

Submission

Path-Loss Exponents ofUltra Wideband Signals in Line-of-Sight Environments

Shunsuke Sato and Takehiko KobayashiCommunications Research Laboratory

Tokyo Denki University

Presented by Honggang Zhang, Yuko RikutaCommunications Research Laboratory

March 2004

Communications Research Laboratory Slide 3

doc.: IEEE802.15-04-0111-00-004a

Submission

Table of contents

• Background • Narrowband two-path model• Conventional UWB two-path model• Proposal of a new UWB two-path model formula• Experimental verification • Conclusion

March 2004

Communications Research Laboratory Slide 4

doc.: IEEE802.15-04-0111-00-004a

Submission

Background

Conventional UWB path-loss models• Free Space : path loss exponent = 2• UWB Two path model [1] :

– Direct wave plus reflected wave from the ground plane– Path loss exponent changes from 2 to at a breakpoint– Breakpoint distance = 2 m (no reason given)– Applicable to the order of meters (?)

• Another UWB two path model [2]– Breakpoint distance is not given

Proposal for a new line-of-sight path loss formula of UWBsignals in the presence of the ground plane reflection.

March 2004

Communications Research Laboratory Slide 5

doc.: IEEE802.15-04-0111-00-004a

Submission

Narrowband two-path model [3]

x

Transmittingantenna

Receivingantenna

Direct wave

ReflectedwavePlanar ground

h T

h R

March 2004

Communications Research Laboratory Slide 6

doc.: IEEE802.15-04-0111-00-004a

Submission

Path-loss based on the narrowband two-path model

1 0 1 0 0 1 0 0 0

6 0

8 0

1 0 0

1 2 0

1 4 0

D i s t a n c e [ m ]

Pat

h lo

ss [

dB]

T w o - p a t h m o d e l ( 1 0 . 6 G H z )D i r e c t w a v e o n l y ( 1 0 . 6 G H z )

hT = hR = 1 m ， = 1 , =

Path loss exponent changes 2 to 4 at the breakpoint

Breakpoint

March 2004

Communications Research Laboratory Slide 7

doc.: IEEE802.15-04-0111-00-004a

Submission

The narrowband two-path model formulaDistance between the transmitting and receiving antennas x,transmitting antenna height hT, receiving antenna height hR,

frequency f ， velocity of the light c, and ground reflection

coefficient exp ( j)

1

22

2cos21

4log10]dB[

c

lf

fx

cL

　x

hhl RT2

March 2004

Communications Research Laboratory Slide 8

doc.: IEEE802.15-04-0111-00-004a

Submission

Breakpoint distance• The Freznel zone distance [3]:

• The linear envelope with a slope of x2 intersects the line of approximation with a slope of x4 :

RT

f

hhD

4

RT

b

hhD

2

Frequency fD bD

3.1 GHz 41.6 m 64.9 m

10.6 GHz 142 m 222 m

hT = hR = 1 m

March 2004

Communications Research Laboratory Slide 9

doc.: IEEE802.15-04-0111-00-004a

Submission

The proposed UWB two-path model formula [4]

•　 The path loss of a UWB the integral of the CW.Distance between the transmitting and receiving antennas x ,transmitting antenna height hT, receiving antenna height hR,lowest frequency fL ， highest frequency fH ， velocity of the light c, and ground reflection coefficient exp ( j).

1

22

2cos21

4

1log10]dB[

H

L

f

fLH

dfc

lf

fx

c

ffL

　x

hhl RT2

March 2004

Communications Research Laboratory Slide 10

doc.: IEEE802.15-04-0111-00-004a

Submission

Predicted UWB path-loss characteristics

1 0 1 0 0 1 0 0 0

4 0

6 0

8 0

1 0 0

1 2 0

1 4 0

D i s t a n c e [ m ]

Pat

h lo

ss [

dB]

P r o p o s e d t w o - p a t h m o d e lD i r e c t w a v e o n l y

　hT = hR = 1 m, = 1, =, frequency=3.1-10.6 GHz ．

March 2004

Communications Research Laboratory Slide 11

doc.: IEEE802.15-04-0111-00-004a

Submission

Dependence of fL and bandwidth

1 0 1 0 0 1 0 0 0

4 0

6 0

8 0

1 0 0

1 2 0

1 4 0

1 6 0

D i s t a n c e [ m ]

Pat

h lo

ss[d

B]

1 0 1 0 0 1 0 0 0

4 0

6 0

8 0

1 0 0

1 2 0

1 4 0

1 6 0

D i s t a n c e [ m ]

Pat

h lo

ss [

dB]

fL = 3.1 GHz fL = 6.0 GHz

hT =hR =1 m

March 2004

Communications Research Laboratory Slide 12

doc.: IEEE802.15-04-0111-00-004a

Submission

Breakpoint distances and path-loss exponentscalculated by the proposed formula

Path loss exponent Bandwidth

[GHz]

Breakpoint

distance [m] d<Db d>Db

7.5 97 1.8 4.0

0.75 72 1.9 4.0

0.075 65 2.0 4.0

0.0075 64 2.0 4.0

CW 64 2.0 4.0

fL = 3.1 GHz , hT = hR = 1 m

March 2004

Communications Research Laboratory Slide 13

doc.: IEEE802.15-04-0111-00-004a

Submission

Breakpoint distance

0 2 4 6 8 1 0

0 . 4

0 . 6

0 . 8

1

1 . 2

1 . 4

1 . 6

B a n d w i d t h [ G H z ]

Bre

akpo

int d

ista

nce 　

[×2

h T h R

/ ]

L

( L + H ) / 2

( L

H ) 1 / 2

RT

b

hhD

2

fL=3.1 GHz

2HL

is the most appropriate:

March 2004

Communications Research Laboratory Slide 14

doc.: IEEE802.15-04-0111-00-004a

Submission

Experimental setup

d0.

1 m

0.1

m

Transmitting antenna

Receiving antenna

VNA

　Bandwidth ： 3.1-10.6 GHz, Polarization ： Vertical

x

March 2004

Communications Research Laboratory Slide 15

doc.: IEEE802.15-04-0111-00-004a

Submission

Experimental verification

0 . 1 1 1 0

0

2 0

4 0

6 0

8 0

1 0 0

D i s t a n c e [ m ]

Pat

h lo

ss [

dB]

U W B ( P r o p o s e d f o r m u l a )C W ( 3 . 1 G H z )C W ( 1 0 . 6 G H z )M e a s u r e m e n t s

March 2004

Communications Research Laboratory Slide 16

doc.: IEEE802.15-04-0111-00-004a

Submission

Conclusion

• Derived a new UWB two-path model formula

– The path-loss exponent of UWB signals changes from approximately 2 to 4 at the breakpoint.

– Breakpoint distance = ,

• Confirmed by an indoor experiment

RT hh2

2HL

March 2004

Communications Research Laboratory Slide 17

doc.: IEEE802.15-04-0111-00-004a

Submission

References [1] ITU-R Doc. 1-8/047-E, March 28, 2003. [2] ITU-R Doc, 1-8/32-E, Jan 16, 2003. [3] W. C. Y. Lee, Mobile Communications Engineering,

2nd ed., pp. 116-120, McGraw-Hill, New York, 1982. [4] S. Sato and T. Kobayashi, “Path-loss exponents of

ultra wideband signals in line-of-sight environments,” 2004 IEEE International Symposium on Spread Spectrum Techniques and Applications, Sydney, Australia, Aug. 30-Sept. 2, 2004, submitted.