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School of Information and Communication Technology

Providing Gigabit Internet to High Speed Trains?

- A Wireless@KTH Seed Project

Claes Beckman

Director Wireless@KTH


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

http://www.goodlogo.com/extended.info/tele2-logo-2873


Goals Identify radio requirements for providing Gigabit connection to a train using:

• Carrier aggregation

• MIMO


Background

The Global perspective


• 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


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


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


”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)


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


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


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:.

11

Presenter

Presentation Notes

Give an introduction to each method and the problems faced in each


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.

http://www.3gpp.org/


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….

http://www.huawei.com/en/index.htm


The Swedish perspective


Passenger Internet on trains 2002 -2012

http://www.teliasonera.com/sv/newsroom/nyheter/2012/osten-makitali-awards/


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


17 Icomera confidential

Aggregating on IP-level

Presenter

Presentation Notes

SureWAN is Icomera's patented core technology that provides aggregation and handover support using multiple communication links. SureWAN requires that the client is able to use the included communication links to send UDP packets on one port (default 11235) on a single IP address. Note: The same IP address is used for all communication links. Network infrastructure must support the routing of this traffic.



Aggregating network capacity

x3 x2

x2 x2

Operator 2 Operator 3

Operator 1


19

Connected train



The Connected Train


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


Passanger internet 2020


4000 times cheaper


? times cheaper

2002 vs 2020 1000.000 times faster

? times cheaper

5G


Master Thesis project


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

mailto:[email protected]




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.

25

Presenter

Presentation Notes

Discuss the effect of the parameter on MIMO performance. High spped will have higher Doppler shift which will cause phase shifts on the different received signal paths


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.

26

Presenter

Presentation Notes

Discussing the simulation Environments, and the measurements parameters


Simulation antenna geometry

27

Presenter

Presentation Notes

This present s the antenna geometry used in the simulation. The mathmatical model used is provided in the report. The system capacity was calculated as a sum of parallel SISO system with different gain according to Eign values of the channel. The path length between the nth transmetted signal to the mth rx-ed antenna were calculated. To have a non-zero channel paths gain the inner product of the channel matrix vector should be zero which results the following relation, as can be seen it depends on the distance and the tx and RX separation and the number of antenna used


Simulation Results

28

Pathloss Model �=2.6 Average velocity=175 km/h

Simulation MIMO capacitt

Presenter

Presentation Notes

Here we can see the results of the simulation , the path loss model was used with path loss exponant=2.6 and average velocity =175km/h. as we can see increasing the number of antenna will increase the spectral efficacy of the system. Each SNR value presents different distance between the train-BS, and results on different receiver antenna separtion


Relation between inter-elements receiver distances and TX-RX distance (CN<2dB)

29

Presenter

Presentation Notes

As can be seen the separation between receiver antenna elements depends on the distance between the train and the BS, this separation values found at 900MHz band and to give the best MIMO performance as can be seen from the CN values<2


Comparison Between simulation and fixed receiver elements distances to λ/2

30

Presenter

Presentation Notes

Here we compare the model used with fixed anntenna separation to lambda/2 on all distances between train to BS


Rohde & Schwarz Universal Radio Network Analyzer equipment (TSMW)

31

• 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.

Presenter

Presentation Notes

Introduction to TSMW and the functions it provide.


Measurements setup

32


900 MHz coverage (measurements)

33

LTE 900 Coverage along the track

Presenter

Presentation Notes

The cover points were mapped using mapinfo. The coverage map agrees with the map provided by tele2, which means that the critiera chsoen for coverage agrees with tele2 RF prediction for coverage


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.

34

Presenter

Presentation Notes

The mimo performance was evaluated according to the average CN reading on the whole channel, CN less than 10 means that the channel is weel conditioned to support MIMO and the strongest path have gain 1-3.16 times the weakest path gain


MIMO statistics

35

70% 68% 63% 60%

Presenter

Presentation Notes

Here we calculate the statistics for different MIMO performance as we can see the 10.5m, 37% of the points support MIMo on the whole channel, if we sum up the MIMO working with the MIMO working but unstable we get


MIMO Speeds Statistics

36

MIMO v.s. Speed

Presenter

Presentation Notes

In the slides we show the speed statsitics on MIMO working point and MIMO working but unstable and on all the covered point as we can see on the average for all scenarios 75% of MIMO working points occurs with speed>100km/h which proves that MIMO works with high speed but in the same time we have an average of 74% of the covered points collected at speed >100km/h so we couldn’t related the MIMO performance with the speed


Average Throughput

• TSWM calculates the throughput according to MIMO/resource block decision

37


Plausibility for achieving Gigabit

38


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.

39


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