Tr@Ins6 Trackside Communication Herman Claus

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Handover solution for Pico-Cells Herman Claus based on work from Tom Van Leeuwen Siemens, Nokia Siemens Networks, OTN

Transcript of Tr@Ins6 Trackside Communication Herman Claus

Page 1: Tr@Ins6 Trackside Communication   Herman Claus

Handover solution for Pico-Cells

Herman Claus – based on work from Tom Van

Leeuwen

Siemens, Nokia Siemens Networks, OTN

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Outline

The Project and The Company

Problem statement

Existing solutions

Radio over Fibre solution

WLAN Fast Handover

Supporting Hardware

Future evolution

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The Project and the Company

During the project, the Siemens Herentals company

went through a lot of changes

At the start, Siemens Herentals (formerly Atea) formed the

Com Division of Siemens Belgium

Two departments were interested in this project

Siemens OTN department : world leader in track-side communication

for metro, also interested in trains etc.

IP-on-trains for TGV by Siemens Services department

The project received a GO with a dual goal

Build up and exchange knowledge about IP-on-trains

Good partners

Own knowledge from Services

Build up knowledge about communication with metro

Experimental technology for OTN

IBBT knowledge

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The Project and the Company

During the project

Siemens Com carved out from Siemens

Nokia Transmission Systems carved out from Nokia

Both merged to form Nokia Siemens Networks

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The Project and the Company

In Herentals

Siemens Com merged with Nokia Transmission Systems

Corporate R&D at Herentals (with the exception of OTN) was

spun off (160 developers) and sold to Devoteam

11 june 2008, after several months of negotiations, it was

announced that the OTN group wil carve out and is due to be

independend july 1st 2008 (GIMV -> see www.gimv.be for

press releases and other information)

All this had its impact on the project

But with the help of he IBBT the project could be finalised

This presentation : only the OTN part of the project is

described

IP-on-trains : contact Walter van Brussel, is explained in the

other WPs

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Problem statement

Communication with metro

Tunnels

Communication with trains

No cheap global wireless coverage

Cost of bandwidth for wireless is high

Bandwitdh x surface should somehow be related to cost

So : use pico-cells

For moving vehicles : handover problem

The faster the more problematic

Same solution for use in tunnels

So there is a technological problem

Remark : there is also an economical one

Base stations are expensive, so picocells are, too.

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Problem statement

Pico-cells are a problem Speed of access point is no problem for most technologies

But handover between cells is

Eg : WiFi : cell of 200 m diameter, speed 120 kmh,

handover every 6 seconds, bad conditions at the edge

Normally handover takes time

Problems with VPN connections etc

What is needed is Seamless handover mechanism

Handover invisible to end-device and to network

Part of the problem solved by other WPs Making handover invisible to end user and network

Same problem as eg satellite etc.

So : concentrate on handover mechanism

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Existing solutions

IST projects FIFTH and MOWGLY

DVB-S2, DVB-RCS

IBBT project FAMOUS

WLAN for fast moving users

InterAccess Point protocol modification proposed

Several algorithms studied

Predicting future access point

Easily adaptable to trains and metro

Making handover mechanism faster

Eg SyncScan algorithm for optimising scanning

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Existing solutions

On the level of fast context switching

Solutions available

Our project

Fast re-association of wireless connection

Be as standard as possible

Two solutions developed by IBBT / Ghent

Radio over fibre based solution

WLAN GAP filler solution

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Radio over Fibre solution

Not part of the project

Idea : between antenna and electronics of the base

station there is a wire

With fibre this wire can span hughe distances

So :

make many antennae, place them widely apart

connect them to one set of electronics

Use overlapping frequencies

neither base station, neither moving access point is aware of

the fact that the moving access point is moving

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Radio over Fibre solution

Some manipulation of datastreams required

See article feb 2007 IEEE Communications Magazine

Problem : economical : cost of antennae-base stations

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WLAN Fast Handover

Handover problem : wireless layer problem When moving from one cell to another cell

Old cell : communication dies

New cell : communication starts up

Dying and starting under bad conditions (low power budget)

Uses lots of time because of robust modulation, broadcast messages etc : normal communication in cell disrupted

Idea :

Separate the handover from normal communication in the cell

Cell 1 uses channel1 : high speed encoding

Cell 2 uses channel2 : high speed encoding

Cell 1 and Cell 2 also support channel3

Channel3 is used for handover,

overlaps in space between cells

Uses soft handover

Low-speed robust encoding

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Fast Roaming WLAN Switch for Rail Systems

Fast Roaming

WLAN AP

Fast Roaming

WLAN AP

Fast Roaming

WLAN AP

Fast Roaming

WLAN AP

Radius

ServerGateway

Fast Roaming

WLAN Client

Data – 802.11a/g Control - 802.11h

WLAN Fast Handover

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WLAN Fast Handover

Client

1 interface

802.11a/g data channel

802.11h control channel

Lightweight Access Points

2 interfaces

same dedicated handover frequency

limited functionality

handoff limited to change in WLAN channel

Switch

association, authentication and security

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Handover

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The GAP filler solution

The problem it solves

The system handles frequency handovers under good signal

conditions

The handover frequency of Channel3 guarantees low speed

but continuous operation of wireless link

The handover does not disrupt the high speed

communication

Association with channel1, channel2 and channel3 can be

done while no data is being transmitted over this paricular

interface

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Hardware

OTN developed a generic supporting hardware

Ethernet layer based data transport

Supporting TDM separated IP channels over one fibre

Transparant to all higher layers

Central switch can ‘directly’ connect to access points

Controlled delay

All channels can be serviced individually

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Hardware

Port10Port1 Port2 Port9

Ethernet programmable

Switch logic

Backplane

Logic 1

Segment 1

10Mbps

Backplane

Logic 2

Segment 2

25Mbps

Backplane

Logic 10

Segment 12

30Mbps

Backplane

Logic 9

Segment 11

10Mbps

User side

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Hardware

FPGA

10/100Mbps 1

2

10

.

.

.

10/100/1000Mbps

10/100/1000Mbps

11

12

10/100Mbps

10/100Mbps

10 * max. 196 Mbps

2 * max. 784 Mbps

Backplane

Maximum 12 segments

Maximum 784 Mbps

Front-end

.

.

.

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Future

Merging of several technolgies needed

Fast handover

Billing and access control

VPN structures

The job ain’t finished yet