MATC Fall Lecture Series: Hamid Sharif
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Transcript of MATC Fall Lecture Series: Hamid Sharif
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
State of Wireless Communications in North American Freight Railroads
Hamid SharifComputer and Electronics Engineering Department
Advanced Telecommunications Engineering Laboratory (TEL)
University of Nebraska – LincolnSeptember 28, 2012
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Wireless in Railroads
• The Five-Year US Federal Railroad Administration (FRA) Strategic Plan for Railroad Research and Development
identifies mobile wireless communication as one of the most critical areas to collect, process, and disseminate information to improve the safety, security, and operational effectiveness of railroads. *
* From: The vision for the future of intelligent railroad systems
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
• Voice – Portions of the voice wireless infrastructure are
more than 30+ years old.• Data
– The Advanced Train Control System (ATCS) wireless data networks (developed in 80s) are only supporting at best 4800/9600 bps and not designed to support today’s multimedia and Internet type applications.
State of Wireless in Railroads
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Project’s Objectives
• Study the suitable wireless technology for current and future of mobile railroads to support:
– high-speed data network for moving trains
– real-time Internet accessibility for trains’ crews, passengers, and ground crews
– improving railroad operating safety and effective operations
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Industry Partners
• Federal Railroad Administration (FRA)• American Association of Railroad (AAR)• Freight Railroads of North America:
– Union Pacific Railroad– BNSF Railway– CSX Transportation– Norfolk Southern Railway– Canadian National Railway– Canadian Pacific Railway
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Research MethodologyReal-World
Test Bed Experiments
Detailed Simulation
ModelsAnalytical
Models
• Build comprehensive simulation models to complement our theoretical study for wireless standard protocols.
• Testbed experiments to study and evaluate the implementation of these technologies for the railroad environments.
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
PHASE 1 - WIFI
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Overview of WiFi Project Phase
• Feasibility of WiFi in mobile railroad environment
• Performance evaluations of WiFi throughput in mobile railroad scenarios
• Study of handoff and Quality of Service (QoS) in WiFi for mobile railroad applications
• Performance evaluations of multimedia applications over WiFi in railroad environments
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
• Investigation of the mobility impact on performance of the 802.11x system with fading under different client velocities
• Analysis of the impact of Doppler shift caused by the velocity of transmitter and receiver
• The multipath interference due to reflections and diffractions from terrain and objects in the radio coverage area and other serious impairment factors
• Study of the bit error rate performances for various velocities with different data rates
Theoretical Approach
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Simulation Models
• 802.11x features designed and implemented:• PHY:
– Determines the impact of noise, fading and Doppler shift– Calculates effects of shadowing, Rician and Rayleigh
fading• MAC:
– Fragmentation and Defragmentation, Data Retransmission– Multirate support (fixed as well as rate adaptation)– Multiple channels, Channel scanning– Synchronization, Power management– Authentication, Association, Re-Association, Handoff
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
WiFi Test bed
• A 3.5 mile section of BNSF track at Crete Nebraska was chosen for it’s close proximity to the UNL, low traffic volumes, and challenging environment (heavy foliage, curves, surrounding hills).
• Test bed utilizes the 802.11 technology to support wireless connectivity between moving trains and fixed Access Points.
• Involved with the design of Testbed were: AAR, BNSF, UP, CSX and CN
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
BNSF WAN
Microwave Link
VPN into BNSF WAN
DSL Link
CC
Router/Gateway
BNSF Core Network
Router/Gateway
AP7 AP6 AP5 AP4 AP3 AP2
NC
NCNCNC CCCCCCCCNCNCNCNC CCCCCC
AP8Crete Depot
AP1Berks East
Internet
Microwave Microwave
Test Bed
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Test Bed Area Map
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
• GPS with real-time mapping– GPS integrated into user interface– Retrieves current location in test bed from GPS device, displays location
of test client and all APs in test bed, calculates distances to all APs and records all information
• WifiPoll with real-time plotting– WifiPoll measures all Wifi adapter information, such as link speed and
status, signal strength, channel, current associated AP, throughput, etc.– Real-time plotting of these results allows real-time evaluation of testing
progress– Graphs include: Tput vs. Time, Tput vs. Distance, Tput histogram, RSSI
(signal strength) vs. Time, RSSI vs. Distance, RSSI histogram, AP association vs. Time
WifiTools Features
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Developed test tools (WifiViz)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Antenna Field Pattern
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Comparison of Test Bed Results and Simulation
12:21:01 12:23:54 12:26:47 12:29:39 12:32:32 12:35:25 12:38:18 12:41:110
1000
2000
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5000
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Comparison of Field Test Results and Simulation Results using GPS Log Information
Field Test 04/27/2006 Simulation using GPSLog
Time
Thro
ughp
ut (k
bps)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Throughput vs. Time
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10:33:36 11:45:36 12:57:36 14:09:36 15:21:36
Time
Th
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bp
s)
Throughput
Velocity vs Time
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10:33:36 11:45:36 12:57:36 14:09:36 15:21:36
Time
Vel
ocity
(mph
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Velocity
Mobility test results
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Throughput vs Distance Comparison - 802.11b 1 Mbps
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0 200 400 600 800 1000 1200 1400 1600 1800 2000
Distance (meters)
Th
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bp
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NS-2
Qualnet
Theory
Field Cutoff
Throughput vs. Distance Comparisons
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Summary of Findings• Benefits of WiFi:
– Operates in unlicensed frequency band, easily accessible for railroads– Good network throughput (about 6 Mbps in good channel)– Supports mobility (tested up to 70 mph)– Inexpensive and readily available equipment and setups– Supports real time multimedia applications
• Drawbacks of WiFi:– Communication Distance limited to only a mile (under excellent LOS conditions
only)– Limited number of channels in unlicensed band creates competition among all
WiFi networks in an area• Interference becomes a problem
– Contention-based multiuser access scheme creates problems for coexistence– No Quality-of-Service mechanism for multimedia applications– No standardized approach for interconnecting WiFi access points
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
PHASE 2 – MOBILE WIMAX
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX - Overview
• Is designed to be a 4G network technology– All-IP network infrastructure, based on IEEE 802.16e
• 802.16e/802.16-2007 is air interface only
• Mobile WiMAX defines end-to-end system
– Supports large communication distances• Initial target distance for Mobile WiMAX was 30 miles
– Supports high throughput• 20 MHz channel provides up to 70 Mbps throughput
– Supports mobility• Mobile nodes are supported even at 120 mph
– Supports QoS and streaming applications• Mobile WiMAX has robust QoS for video and voice applications over wireless
channels
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
• UNL has 5 EBS licenses, centered around Omaha, Lincoln, Kearney (35 miles radius), among them:
Mobile WiMAX – RF Frequency Space
WCG671 – around Lincoln WHR724 – around Omaha
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Simulation Model
Results from Lab Testing and Computer Simulations
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
WiMAX Simulation Model ComparisonFeatures QualNet 4.0 OPNet NS-2 Models:
Taiwan Italy NIST TEL (our model)
Air Interface 802.16e 802.16e 802.16-2004 802.16d 802.16e 802.16-2009
Duplex TDD n/a TDD n/a TDD TDD
PHY Mode OFDMA OFDMA OFDMA n/a OFDM OFDM, OFDMA
ARQ, Hybrid-ARQ Y, N Y, N N, Y N, N N, N Y, Y
Multihop Backhaul n/a n/a N Y N Y
QoS Y Y Y N N I/P
Flow Scheduling Y Y Y N N Y
AMC Support n/a n/a N n/a N Y
Mode Pt-to-MPt n/a Pt-to-MPt Mesh Pt-to-MPt Pt-to-MPt
Realistic RF model n/a n/a N n/a N Y
Mobility Support Y Y N N Y Y
Handoff Schemes Y Y, limited n/a n/a Y Y
Multimedia Support n/a n/a N n/a N Y
Device Emulation n/a n/a N n/a N Y
ASN-GW Support N n/a N N N I/P
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Simulation Results
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Comparison of Theory, Simulation, Tests
qpsk-1/2 qpsk-3/4 16qam-1/2 16qam-3/4 64qam-2/3 64qam-3/40
5000000
10000000
15000000
20000000
25000000
Total Throughput for Simulation, Lab-Test, and Theory
Simu-wimax Test-pBst Theory
Thro
ughp
ut (k
bps)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Predicted Distance for Test Equipment
0 2000 4000 6000 8000 10000 12000 140000
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Mobile WiMAX Throughput vs Distance
64QAM34 DL64QAM23 DL16QAM34 DL16QAM12 DLQPSK34 DLQPSK12 DL
Distance (meters)
Thro
ughp
ut (k
bps)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Sample Simulation Scenarios we are studying
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Event Recorder Data UploadKey Parameters:• 70 mph train speed• 5 km AP Spacing (~3.1 miles)• Total length of 20 km• Uses maximum data transfer rate
0 50 100 150 200 2500
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Event Recorder UL - Throughput
TCP Throughput AP Association
Time (s)
Data
Thr
ough
put (
kbps
)
AP ID
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Event Recorder UL – File Size
FTPFileSize AP Association
Time (s)
File
Size
(Mby
te)
AP ID
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Video Streaming Fairness Comparison
Fairness Impact on Image Quality
0 2 4 6 8 10 12 14 160.5
0.55
0.6
0.65
0.7
0.75
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0.85
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0.95
1
Total Station Number
PS
NR
Fai
rnes
s In
dex
802.16
802.11
Fairness Impact on Throughput
0 2 4 6 8 10 12 14 160.5
0.55
0.6
0.65
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0.75
0.8
0.85
0.9
0.95
1
Total Station Number
Thr
ough
put
Fai
rnes
s In
dex
Throughput Fairness vs. Total Station Number
802.16
802.11
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Video: PKI Neighborhood
Drive around the new Aksarben Neighborhood: Distance to PKI is about 0.5 milesSeveral signal obstructions from buildings in the area.
This is all done under the coverage of a SINGLE WiMAX Base Station!
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Video: Park
Drive around Elmwood Park: Distance to PKI is about 0.4 miles at farthest pointExtreme signal obstruction and scattering from trees in park!
WiFi would fail after the first few yards into the park area!
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Video: Speed and Distance
Drive on West Center road: Distance to PKI is between 0.6 miles and 1.0 miles at end!Signal obstructions from buildings between road and PKI, Doppler shift from 60 mph!
Under the coverage of a SINGLE WiMAX Base Station, with LOS RSSI=-66dBm at 1 mile!
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Multiuser Comparison – WiFi and WiMAX
• WiMAX exhibits more efficiency (less overhead)– WiFi degrades with increased
no. of subscribers– Outcome of contention-based
operation in WiFi– Central resource management
eliminates these issues for downlink, drastically reduces its impact for uplink
• WiMAX also demonstrates better fairness among multiple subscribers
0 2 4 6 8 10 12 14 164
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Station Number
Thr
ough
put(
Mbp
s)
Uplink Performance under N STAs
802.11
802.16
Total Throughput vs. No. of Subscribers
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Mobile WiMAX Field Tests
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Field Tests - Overview
• Field tests designed to provide real-world performance data– Maximum communication distance
– Maximum throughput at different velocities
– Handover performance with and w/o ASN-GW
– Latency, Packet Loss, Quality-of-Service, etc.
• We are utilizing microwave tower sites made available to us by Union Pacific and BNSF
• Preliminary Field Tests have been performed around our campus
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Test Site 1 – UP: Logan, IA
Logan, IA - Tower
Road for WiMAX Tests
Main Antenna Direction Indicator
120degree coverage area of antenna (shaded area)
3 miles (approx.)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Test Site 2 – BNSF: Ashland, NE
Ashland, NE - TowerRoad for WiMAX Tests
Main Antenna Direction Indicator
120degree coverage area of antenna (shaded area)
3 miles (approx.)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Summary
• High-speed data networks is critical for effective railroad operations in mobile environments.
• One technology may not be the solution for all railroad needs.
• Combination of WiFi and WiMAX is a promising solution.
• An integrated solution is needed to support audio and video (multimedia type) applications.
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
UNIVERSITY OF NEBRASKA – LINCOLN COLLEGE OF ENGINEERING
Advanced Telecommunications Engineering Laboratory (TEL)
Contact Information
• Hamid Sharif• Email: [email protected]• Phone: (402) 554-3628• Web: www.tel.unl.edu
• Thank you!