1. WAVE Channel Modeling and the Midamble Insertion Effects
September Sep. 2008
March 2008July 2008
March 2008
doc.: IEEE /0360r0
September 2008
WAVE Channel Modeling and the Midamble Insertion Effects
Date:
Authors:
Slide 1
Stephen McCann, Nokia Siemens Networks

2. Contents Introduction 1 WAVE Channel Modeling 2 3
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Contents
Introduction 1
WAVE Channel Modeling 2
Overview of the Proposed Scheme 3
Performance Analysis 4
Conclusions 5

3. Introduction V2V/V2I communications September 2008 V2V V2I
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Introduction
V2V/V2I communications
V2V application : Vehicle Multi-hop Networking for Vehicle Safety
V2I application : Bi-directional Packet Communication for ITS/Telematics
Accident
GPS
Emergency
Message
Warning Message
Cellular/WiBro
Probe Data
TSP Server
Internet
RSE
Traffic
Information
V2V
V2I
Hopping

4. WAVE Channel Modeling (1/2)
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WAVE Channel Modeling (1/2)
September 2008
V2V and V2I models
Based on the measured data in 5.9GHz band
Long Model: # of mutipath>12
Model
Scenario
PSDU size [bytes]
Vehicle speed [km/hr] 1
V2V - Expressway Oncoming without Wall, 300m - 400m Model
200
140 2
V2I - Urban Canyon, 100 m Short Model
1000
120 3
V2I - Urban Canyon, 100 m Long Model 4
V2I - Expressway, 300m - 400m 140 km/hr Model 5
V2I - Expressway, 300m - 400m 200 km/hr Model 6
V2V - Urban Canyon Oncoming, 100m Short Model 7
V2V - Urban Canyon Oncoming, 100m Long Model 8
V2I - Suburban Street, 100m Short Model 9
V2I - Suburban Street, 100m Long Model 10
V2V - Expressway same direction with wall, 300m - 400m
V2I(Vehicle-to-Infrastructure)= R2V(Roadside-to-Vehicle)

5. WAVE Channel Modeling (2/2)
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WAVE Channel Modeling (2/2)
September 2008
V2I - Urban Canyon, 100 m
(#2, #3)
V2V - Expressway Oncoming without Wall, 300m - 400m Model (#1)
V2I- Expressway, 300m - 400m
(#4, #5)
V2V-Expressway Same Direction
with Wall, 300m-400m (#10)
V2V - Urban Canyon Oncoming, 100m
(#6, #7)
V2I- Suburban Street, 100m
(#8, #9)

6. Channel Model: Example
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Channel Model: Example
Model #1: VTV - Expressway Oncoming without Wall, 300m - 400m Model (Measured parameters)
Tap No.
Path No.
Tap Power (dB)
Relative Path Loss (dB)
Delay
Value
(ns)
Rician K
(dB)
Freq. Shift (Hz)
Fading
Doppler
(Hz)
LOS Doppler (Hz)
Modulation
Fad. Spec. Shape
=Doppler spectrum shape 1
0.0
-1.6
1451 60
1452
Rician
Round 2
-24.9
n/a
884
858
Rayleigh 3
-25.5
1005
486 4
-6.3
-13.1
100
761
655
Classic 3dB 5
-7.5
101
1445 56 6
-25.1
-28.9
200
819
823 7
-29.3
201
1466 75
Flat 8
-35.6
202
124 99 9
-22.7
-25.7
300
1437
110 10
-34.4
301
552
639 11
-27.4
302
868
Classic 6dB
Slide 6

7. Channel Model Simulator
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Channel Model Simulator
Consist of fading generator and TDL (Tapped delay line)

8. Channel Model: Example, PSD (channel #1)
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Channel Model: Example, PSD (channel #1)
Blue curves: Measured data
Red curves: Simulation data

9. Proposed Channel Estimation Scheme
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Proposed Channel Estimation Scheme
September 2008
Mid-amble based Channel Estimation
Update channel information using Mid-amble
Suitable for high mobility
Midamble
VMC Training Structure
Preamble
Data
···
Midamble
Channel
estimation
Equalizer
tracking
& Update
N symbol
Proposed Channel Estimation Method

10. Performance Simulation
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Performance Simulation

11. Performance Analysis: different modulation
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Performance Analysis: different modulation
September 2008
Use the channel model #5 (V2I- Expressway, 300m - 400m)
Various midamble insert rates
- BPSK, 200byte
- 16QAM, 200byte
BPSK: No big difference
16QAM: By increasing midamble insertion rate
 Achieve better performance when SNR is high

12. Performance Analysis: different packet size
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Performance Analysis: different packet size
Use the channel model #5 (V2I- Expressway, 300m - 400m)
Various midamble insert rates
- QPSK, 1000byte
- QPSK, 2000byte
As the packet size increases :
Performance decreases
Need frequent midamble insertion for performance enhancement

13. Performance Analysis: various channels(V2V)
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September 2008
Performance Analysis: various channels(V2V)
Packet size: 2000byte, modulation: QPSK
Channel #1: Expressway Oncoming without Wall
Channel #10: Expressway same direction with wall
Midamble rate is more sensitive
 In bad channel scenario

14. Performance Analysis: various channels(V2I)
September Sep. 2008
September 2008
Performance Analysis: various channels(V2I)
Packet size: 2000byte, modulation: QPSK
Channel #3: Urban Canyon, 100 m Long Model
Channel #9: Suburban Street, 100m Long Model
Midamble rate is more sensitive
 In bad channel scenario

15. Conclusions WAVE channel modeling
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September 2008
Conclusions
WAVE channel modeling
Three V2I channels & Three V2V channels
Consist of WAVE fading generator & TDL(Tapped delay line)
Well matched with the measured data
Performance analysis: the effect of midamble inserting rate
Midamble channel estimation guarantees the performance enhancement
As the modulation size increases
Frequent midamble insertion increases the performance dramatically
As the packet size increases
Frequent midamble insertion increases the performance
Midamble insertion effect is more critical
In bad channel condition
 Trade-off between the midamble rate & Modulation size/packet size

16. September Sep. 2008
September 2008
References
 G. Acosta and M.A. Ingram, “Six time- and frequency- selective empirical channel models for vehicular wireless LANs,” IEEE Vehicular technology magazine, vol. 2, issue. 4, Dec. 2007, pp.4-11.
G. Acosta, “Measurement, modeling, and OFDM synchronization for the wideband mobile-to-mobile channel,” Ph. D dissertation, Georgia Institute of Technology, 2007.
Sang In Kim, Hyun Seo Oh, and Hyun Kyun Choi, “Mid-amble aided OFDM performance analysis in high mobility vehicular channel,” 2008 IEEE Intelligent Vehicles Symposium, June 4-6, 2008 pp