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Providing Gigabit Internet to High Speed Trains?
- A Wireless@KTH Seed Project
Claes Beckman
Director Wireless@KTH
School of Information and Communication Technology
Participants • Mats Karlsson & Martin Bergek, Icomera
• Mohammad Alsali, Per Zetterberg and Claes Beckman, KTH
• Willy Stjernudde Göran Linné and Petter Essén, SJ
• Axel Ericsson and Henrik Andersson, Tele2
• Anders Hedlund Ascom
• Daniel Kerek Delta Node
• Pontus Segerberg Rohde-Schwarz
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Goals Identify radio requirements for providing Gigabit connection to a train using:
• Carrier aggregation
• MIMO
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Background
The Global perspective
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• High-speed rail service in China was introduced on April 18, 2007, and daily ridership has grown from 237,000 in 2007 to 796,000 in 2010
• The trains typically reach operational speeds of up to 380 km/h and carries up to 1200 passengers
High speed rails in China
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Global expanision of HS Rail
• In the world there is today some 17000km high speed rail
• Some 9000km is currently being buildt and 16000km is planed
• Year 2025 förväntas det existera ca 43000km snabbtågsräls i världen av vilket ca 1/3 kommer att ha byggts i Kina
• 2015 HS rail is expected to transport 10 million passangers per day!
• All these passangers will require ICT services on board
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What is the need for ICT on trains
It is easy to envision what type of infotainment services that can be of interest on board:
- Mobile telephony - Information - Cloud servces
”Cloud computing” Social media E-mail IP-TV News
- Entertainment Film Games
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”State of the Art Technology”,
• Today there exists a number of different technologies for providing internet on trains
- Satellite systems - Dedicated radio networks - Connection to the cellular 3G/4G
network
• Operating these services can be either - Train operators (TOC) - Mobile operators (MOB) - A System Integrator (SI)
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Satellite Connection
• Satellite connection to the traina was a common solution before the roll-out of the 3G networks
• However, it is an expensive low data rate solution.
• Today, this type of solution is mainly used in rural areas with absolutely no other options for connectivity: e.g. rural parts of Russia
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Dedicated Terestreal Networks
• An other alternative is to buil a terestreal radio network dedicated for providing the connectivity to the train
• Flash-OFDM on the 450-band is one standard that has been depolyed for commercial use for this service
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Connecting to cellular networks
Several options: 1.Personal dongle: Connection directly to BS, signal penetrates train window .
2.RF repeaters: Good signal quality. Limited by the operator coverage.
3.Centralized Wi-Fi system connected to the cellular systems:.
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What about 3GPP?
• In 2008 China Mobile proposed that ”relays” would be implemented in the 4G standard, LTE, in order for the operators to be able to support mobile broadband for ”group mobility”, i.e. passangers onboard busses and trains
• After the launch of the high speed rail road between Beijing and Shanghai in 2011, China Mobile has brought up the issue to 3GPP again.
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Huawei….
• In 2011 Huawei presented an ICT solution for trains
• Huawei concludes that the capacity needed per train set will be in the order of Gigabit allready within 5 years.
• In order to reach those capacities, Huawei proposes a solution that is based on
- Carrier aggregation - Multiple networks - Multipl standards
Sounds innovative but is it new….
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The Swedish perspective
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Passenger Internet on trains 2002 -2012
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Icomera History
1999 – Icomera founded at Chalmers’ Studenthem!
2002 – First on train installation. First commercial use of the solution in a mobile environment
2003 – First commercial roll-out in Sweden, LINX
2004 – First commercial contract outside of Sweden with GNER in the UK
2005 – Full fleet roll-out of SJ’s trains in Sweden
2006 – Full fleet deployment for GNER.
2008 – Acquisition of Moovera. First US contract
2009 – New installations in Spain, Ireland and Germany
2010 – Icomera X product platform introduced
2011 – New installations in Denmark, France, and Switzerland
2012 – Full fleet roll out in Ireland and in Czech Republic
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17 Icomera confidential
Aggregating on IP-level
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Aggregating network capacity
x3 x2
x2 x2
Operator 2 Operator 3
Operator 1
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Connected train
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The Connected Train
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10 years of Passanger Internet on board SJ X2000
• 2002 2002 - Satellite 1 Mbit/s 1 MSEK/per year
2002 – GPRS 10 kbit/s, 20 SEK/MB, 1 MB per hour per passenger
• 2012 2012 – LTE 10 Mbit/s, 0.005 SEK/MB 50 MB per hour
2012 vs 2002 1000 times faster
4000 times cheaper
4G
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Passanger internet 2020
2012 vs 2002 1000 times faster
4000 times cheaper
2012 vs 2002 1000 times faster
? times cheaper
2002 vs 2020 1000.000 times faster
? times cheaper
5G
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Master Thesis project
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LTE MIMO Performance Measurements on Trains
Student : Mohammad Alasali ([email protected])
Supervisor : Claes Beckman ([email protected])
Examiner : Ben Slimane ([email protected])
(September 2012) This work conducted in collaboration with: Icomera, Tele2, R&S and SJ
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Problem Formulation
• Is it plausible to use MIMO antennas to reach higher capacities in LOS environments on board trains?
• How is the MIMO performance in LOS dependent on:
- Distance between base-stations and train. - Distance between receiver antenna elements. - Train speed.
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Methodology
• Simulation: using Matlab to simulate typical LOS environments with different train-to-BS distances.
• Measurements: measurements using LTE scanner on the main track between Stockholm-Gothenburg on board train SJ X2000, eight antenna were mounted at 4m height.
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Simulation antenna geometry
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Simulation Results
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Pathloss Model �=2.6 Average velocity=175 km/h
Simulation MIMO capacitt
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Relation between inter-elements receiver distances and TX-RX distance (CN<2dB)
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Comparison Between simulation and fixed receiver elements distances to λ/2
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Rohde & Schwarz Universal Radio Network Analyzer equipment (TSMW)
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• TSMW used to optimize conventional wireless networks.
• In this project TSMW used to scan LTE 900MHz network (Tele2 own this band)
- Coordinates of both BS and train. - RSRP. - RS-SINR. - GPS speed. - Channel matrix, RI and CN on each resource block.
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Measurements setup
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900 MHz coverage (measurements)
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LTE 900 Coverage along the track
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MIMO Performance
• To evaluate MIMO performance the CN readings where analyzed on covered points:
1. MIMO works: CN<=10dB (stronger path have gain 1-3.16
times the weakest path).
2. MIMO works but unstable : 10dB<CN<=15dB (3.16-5.6), unstable means that the channel support rank 2, but not all channel resource blocks support MIMO.
3. MIMO doesn’t work: CN>15dB.
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MIMO statistics
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70% 68% 63% 60%
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MIMO Speeds Statistics
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MIMO v.s. Speed
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Average Throughput
• TSWM calculates the throughput according to MIMO/resource block decision
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Plausibility for achieving Gigabit
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Conclusion
• MIMO systems actually works in LOS environments
• The higher the speed of the rain is, the better MIMO seem to work.
• The receiver inter-elements is dependent on the average train-BS distance.
• To achieve optimum MIMO performance, base stations should be close to the track and the antennas on the train well separated (>10m)
• Using LTE-A and its features such as 8x8 MIMO and carrier aggregation is a promising technology for future provisioning of internet on board trains.
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Welcome Aboard
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