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9 Mar 2007
UBC – IEEE Workshop on Future Communications Systems
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UWB Radiowave Propagation within the Passenger Cabin of a
Boeing 737-200 AircraftJames Chuang, Ni Xin, Howard Huang, Simon Chiu, and David G. Michelson
jimc|[email protected]
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I. Introduction• Studies of wireless aboard aircraft have been conducted by:
– German Aerospace Centre (DLR) and the European Union’s WirelessCabin project
– Old Dominion University and NASA– Qualcomm and Boeing
• These have emphasized:– Studies and field trials for existing technologies,– Measurement of RF coverage using client devices,– Simulation of aircraft interiors using RF coverage tools, – Characterization of the wideband channel response.
Past Work and Its Limitations• UWB holds great promise for facilitating,
– deployment of high data rate multimedia and network access services.
– operations and maintenance through deployment of sensor networks and precise positioning system.
• Past efforts to develop measurement-based models for UWB propagation channels have focused on residential, office, outdoor and industrial environments
• No previous published work concerning the UWB propagation channel within aircraft passenger cabin or the effect of human presence within such environments.
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Where do we fit in?
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Conventional Environments
Aircraft Environment
ConventionalWireless Systems
UWBUBCRSL
IEEE 802.15.3a/4a
Many Organizations
DLR & EUNASA & Boeing
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Objectives• Characterize large-scale aspects of UWB propagation within
the passenger cabin of an aircraft:– Distance and frequency dependence of path loss.– Time dispersion
• RMS delay spread• Parameters of the AR-FD channel model.
– The effect of human presence.• Prepare for the next step: characterization of the detailed
structure of the UWB channel impulse response.
Outline• Section II – Measurement Approach
– Point-to-Multipoint and Peer-to-Peer Configurations• Section III – UWB Channel Sounder
– Implementation, Settings and Configuration– Data Collection, Receiver Sampling Strategy
• Section IV – Results– Distance and Frequency Dependence of Path Loss– Time Dispersion Parameters and AR-FD Channel
Modeling• Section V – Conclusions
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II. Measurement Approach
• The main cabin of a Boeing 737-200 is:• 21 m in length,• 3.54 m in width,• 2.2 m in height.
• We have considered both point-to-multipoint and peer-to-peer wireless system configurations.
Point-to-Multipoint Configuration
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• Transmitting antenna (access point) on the ceiling
• Receiving antenna (user terminals) placed at headrest, armrest and footrest levels.
RX ANTENNA
Peer-to-Peer Configuration
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• Transmitting antenna (user terminal) placed at headrest, armrest and footrest levels
• Receiving antenna (user terminal) placed at headrest, armrest and footrest levels.
RX ANTENNA TX ANTENNA
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III. UWB Channel Sounder
LNAPA
MeasurementReceiver
Laptop
~
RB
Control Signals
Source
Reflections from objects in the environment
Display/ Controller
Transmitting Antenna
VNA
Receiving Antenna
Implementation• An Agilent E8362B vector network analyzer (VNA) was
used to collect complex frequency response of the channel throughout the aircraft.
• Two UWB biconical antennas, Electro-metrics 6865, were used as both the transmitter and receiver.
• Two 15 m long LMR-400 UltraFlex coaxial cables were used to connect the antennas to the VNA.
• Calibration is done up to the antenna connectors.• Both the antennas and the channel are treated as the device
under test by the VNA.
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Configuration and Settings
VNA SettingsStart Frequency 3 GHzStop Frequency 10.6 GHzFrequency Steps 6401Transmit Power 5 dBmIF Bandwidth 3 kHzSweep Time 2 secTime Resolution 132 psec
EM-6865 UWB Biconical Antenna
Agilent E8362B PNA
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Data Collection• Point-to-multipoint configuration
• Tx antenna• near the cabin ceiling.• at 3 locations throughout the cabin.
• Rx antenna • at headrest, armrest, footrest.• at over 50 locations throughout the cabin.
• Redundancies in the data base allowed us to check the consistency of our results.
• At 3 transmitter locations,• At over 50 receiver locations.
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Receiver Sampling StrategyAisle
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Row 8
Row 9
Row 10
Row 11
Row 12
Row 13
Row 14
Row 15
Row 16
Row 17
Row 18
Row 19
Row 20
Row 21
Row 22
Passengers
12
4
3
1
11
10
98
7
65
19
16
1514
13
1817
22
2120
ABCDEFTx LocationPoint-to-Multipoint
2
23 24
Aisle
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Row 8
Row 9
Row 10
Row 11
Row 12
Row 13
Row 14
Row 15
Row 16
Row 17
Row 18
Row 19
Row 20
Row 21
Row 22
12
4
3
1
11
10
98
7
65
19
16
1514
13
1817
ABCDEF
Tx LocationPoint-to-Multipoint
2
Aisle
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Row 8
Row 9
Row 10
Row 11
Row 12
Row 13
Row 14
Row 15
Row 16
Row 17
Row 18
Row 19
Row 20
Row 21
Row 22
2
ABCDEF
Tx LocationPoint-to-Multipoint
1 3
4 5 6
7 8 9
10 11 12
13 14 15
16 17 18
19 20 21
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IV. Results• We processed our measurement database to characterize large-
scale aspects of UWB propagation within the passenger cabin of an aircraft:– Distance and frequency dependence of path loss.– Time dispersion
• RMS delay spread• Parameters of the AR-FD channel model.
– The effect of human presence.
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Distance & Frequency Dependence of Path Loss• We estimated the parameters of the IEEE 802.15.4a UWB
path loss model:
where d and f are distance and frequency, respectively, d0and fc are the reference distance and frequency, n and κ are the distance and frequency exponent, and k is a constant.
• The distance and frequency are assumed to be independent of each other.
( )2
0
,n
pc
d fG d f kd f
κ− −⎛ ⎞ ⎛ ⎞
= ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠
Distance Dependent Path Loss• We averaged path gain across the entire frequency response
and fit the results to the power law path loss equation
in dB scale
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( ) ( ) 2
1
1 ,M
ii
PL d H f dM =
= ∑
( ) 0 100
10 logdBdPL d PL n Xd σ
⎛ ⎞= + +⎜ ⎟
⎝ ⎠
Path Gain with No Passengers
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100 101-70
-65
-60
-55
-50
Distance [m]
Pat
h G
ain
[dB
]Headrest
Armrest
Footrest
Path Gain with Passengers in Every Other Seat
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100
101
-70
-65
-60
-55
-50
Distance [m]
Path
Gai
n [d
B]
Headrest
Armrest
Footrest
Path Gain with Passengers in Every Seat
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100
101
-70
-65
-60
-55
-50
Distance [m]
Path
Gai
n [d
B]
Headrest
Armrest
Footrest
Distance Dependent Path Loss Parameters
Passenger Density
Mounting Point
Path loss exponent,n
1-m Intercept(dBm)
Location variabilityσ (dB)
Headrest 2.1 -40.0 5.0Armrest 2.2 -42.6 5.1
No Passengers
Footrest 2.2 -45.1 4.7Headrest 2.4 -39.7 5.3Armrest 2.5 -43.1 5.2
Passengers in every other seats
Footrest 1.9* -49.1* 3.8*Headrest 2.6 -39.9 4.0Armrest 2.5 -46.0 3.9
Passengers in every seat
Footrest 1.7* -50.9* 2.4*
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* only measured in aisle seats
Frequency Dependent Path Loss
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( )PL f f κ−∝
4 6 8 10-90
-80
-70
-60
-50
-40
-30
Frequency [GHz]
Pat
h G
ain
[dB
]
κ(d) with Receiver at Headrest
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2 4 6 8 10 12 14-1.5
-1
-0.5
0
0.5
1
1.5
Distance [m]
kapp
a
κ(d) with Receiver at Armrest
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2 4 6 8 10 12 14-1.5
-1
-0.5
0
0.5
1
1.5
Distance [m]
kapp
a
κ(d) with Receiver at Footrest
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2 4 6 8 10 12 14-1.5
-1
-0.5
0
0.5
1
1.5
Distance [m]
kapp
a
Time Dispersion Parameters• Power Delay Profile
• RMS delay spread
• The ratio of power in the LOS and scattered components
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( )
( )
2k k
kRMS
kk
P
P
τ ττ
τ=∑∑
( )
( )LOS k
LOS k
SCAT SCAT kk
PPP P
τ
τ=∑∑
( ) ( ) 2k k k
kP aτ δ τ τ= −∑
CDF of RMS Delay Spread
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5 10 15 20 25 300.0
0.2
0.4
0.6
0.8
1.0
RMS Delay Spread [ns]
Cum
ulat
ive
prob
abili
ty
HeadrestArmrestFootrest
CDF of the Ratio of Power in the LOS and Scattered Components
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0 1 2 3 4 50.0
0.2
0.4
0.6
0.8
1.0
PLOS/PSCAT
Cum
ulat
ive
prob
abili
ty
HeadrestArmrestFootrest
Autoregressive Frequency Domain Channel Model
• The Difference Equation,
• The Poles,
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1
ˆ ˆ( , ; ) ( , ; ) ( , ; )p
k i k i ki
H f t x a H f t x U f t x−=
+ =∑
( )( )1
1
1
1k
ii
G zp z−
=
=−∏
AR-FD Model – Pole Distribution for Receiver at Headrest
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-1.0 -0.5 0.0 0.5 1.0-1.0
-0.5
0.0
0.5
1.0
Real Part
Imag
inar
y Pa
rt
all seatsoccupied
50% of seatsoccupied
emptyaircraft
AR-FD Model – Pole Distribution for Receiver at Armrest
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-1.0 -0.5 0 0.5 1-1.0
-0.5
0.0
0.5
1.0
Real Part
Imag
inar
y Pa
rt
all seats occupied
50% of seatsoccupied
empty aircraft
AR-FD Model - Pole Distribution for Receiver at Footrest
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-1.0 -0.5 0.0 0.5 1.0-1.0
-0.5
0.0
0.5
1.0
Real Part
Imag
inar
y Pa
rt
all seats occupied
50% of seatsoccupied
emptyaircraft
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V. Conclusions• We characterized the large-scale aspect of UWB propagation
in point-to-multipoint configuration within the passenger cabin of a mid-size airliner.
• These results include:– Distance and frequency dependence of path loss,– Time dispersion parameters,
• RMS delay spread• PLOS/PSCAT
• Parameters of the AR-FD channel model– The effect of human presence.
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Conclusions - 2• The results will assist those:
– planning UWB deployment and field trials in aircraft,– wishing to verify the results of eletromagnetic simulations
of aircraft interiors,– wishing to simulate UWB aircraft systems with realistic
channels.
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Future Work• Peer-to-peer configuration• Going beyond the passenger cabin, e.g., cargo holds, wings,
cockpit, etc.• Characterization of channel impulse response • Small-scale fading parameters.
Acknowledgements• We are grateful to the management and staff of the BCIT
Aerospace Technology Campus at Vancouver International Airport for providing us with access to their Boeing 737-200 aircraft during the course of this study.
• We thank Ivan Chan, Alex Lee, Chris Pang, Cecilia Yeung, Chad Woodworth, and especially Shahzad Bashir for their considerable assistance during the data collection phase of this study.
• This work was supported by Bell Canada’s University Laboratories R&D Program, Nokia Canada, and the Natural Sciences and Engineering Research Council of Canada.
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References1. N.R. Diaz and M. Holzbock, “Aircraft cabin propagation for multimedia
communications,” Proc. EMPS 2002, 25-26 Sep. 2002.2. C.P. Niebla, “Coverage and capacity planning for aircraft in-cabin wireless
heterogeneous network,” Proc. IEEE VTC 2003-Fall, 6-9 Oct. 2003, pp. 1658-1662.
3. G.A. Berit, H. Hachem, J. Forrester, P. Guckian, K.P. Kirchoff, B.J. Donham, “RF propagation characteristics of in-cabin CDMA mobile phone networks,”Digital Avionics Systems Conference, 30 Oct. – 3 Nov. 2005, pp. 9.C.5-1---9.C.5-12.
4. N.R. Diaz and J.E.J. Esquitino, “Wideband channel characterization for wireless communication inside a short haul aircraft,” Proc. IEEE VTC 2004 Spring, 17-19 May 2004, pp. 223-228.
5. A.F. Molisch, “Ultrawideband propagation channels: Theory, measurement, and modeling,” IEEE Trans. Veh. Technol., vol. 54, no. 5, Sep. 2005, pp. 1528-1545.
References (cont.)6. A.F. Molisch, et al., “A comprehensive standardized model for ultrawideband
propagation channels,” IEEE Trans. Antennas Propag., vol. 54, no. 11, Nov. 2006, pp. 3151-3165.
7. T.B. Welch, et al., “The effects of the human body on UWB signal propagation in an indoor environment,” IEEE J. Sel. Areas Commun., vol. 20, no. 9, Dec. 2002, pp. 1778-1782.
8. S.J. Howard and K. Pahlavan, “Autoregressive modeling of wide-band indoor propagation,” IEEE Trans. Commun., vol. 40, no. 9, Sep. 1992, pp. 1540-1552.
9. S.S. Ghassemzadeh, R. Jana, C.W. Rice, W. Turin, and V. Tarokh, “Measurement and modeling of an ultra-wide bandwidth indoor channel,” IEEE Trans. Commun., vol. 52, no. 10, Oct. 2004, pp. 1786-1796.
10. N. Xin, and D. G. Michelson, “Frequency domain analysis of the IEEE 802.15.4a standard channel models,” Proc. IEEE WCNC 2007, 11-15 Mar. 2007.
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