Tr@Ins4 Onboard Communication Frederik Vermeulen
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Transcript of Tr@Ins4 Onboard Communication Frederik Vermeulen
Mobility scenarios
Legend:
AC
DE
B B B B
C C
FD
D: vehicle wireless connection pointE: way-side wireless connection pointF: station WiFi hotspot
A
LegendA: personal WiFi deviceB: on-board WiFi hotspotC: on-board services switch
Mobility scenarios
Mobility scenarios (1)
AC
DE
B B B
C C
C
DE
B B B
C C
A
1 2 3
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Mobility scenarios (1)
User moving inside train
Mobility scenarios (2)
Train moving -> handover
C
DE
B
C C
FD
1
A
B B2 B3
A
Mobility scenarios (3)
User leaving the train
B
FD
A
B
FD
A
6
NAT
DHCP
AAA
Train managementInternet
Local content
Mobility Management
Mobility Management
Tr@ins architecture
Onboard network components
TrainSwitch
TrainSwitch
On-board server: - voice/video communication, passenger information, entertainment - content server - web, mail cache - TCP accelerator - crew authentication, gateway - train management (TCMS) interface
Mobility Management
WiFiBS
WiFiBS
WiFiBS
Wayside linktechnologies
WiFiBS
WiFiBS
WiFiBS
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Onboard use cases
Seamless connectivity and Quality of Service for
- crew moving through the train
- passengers moving through the train
I. Moerman, B. Jooris, A. Schoutteet, F.Vermeulen
Applications on train
Passengers + Crew• on-board content (web/MM)• email• internet• video/audio streaming• VoIP
• e-ticketing• maintenance, manuals• CCTV
Applications
Vertical handovers when a crew terminal switches between the wired and the wireless connection
OSS
BSMAR
GP
RS
WLA
NSatellite
AP xAP-AP-
AP-AP-AP-
AP-AP-AP -
BS BS
OSS OSS contentx
OSS
BSMAR
GP
RS
WL
ANSatellite
AP xAP-AP-
AP-AP-AP-
AP-AP-AP -
BS BS
OSS OSS contentx
Two layer 2 handovers
Horizontal handover when a user is moving inside the train
OSS
BSMAR
GP
RS
WLA
NSatellite
AP xAP-AP-
AP-AP-AP-
AP-AP-AP -
BS BS
OSS OSS content
OSS
BSMAR
GP
RS
WL
ANSatellite
AP xAP-AP-
AP-AP-AP-
AP-AP-AP -
BS BS
OSS OSS content
x
x
Two layer 2 handovers
Connectivity requirements
bandwidth
latency (< 50 ms for voice)
continuous connectivity (=guaranteed <50ms latency at
handover) available solutions 500 ms
compatible with standards 802.3, 802.11
Requirements
Vertical handover: wired-wireless
Convergence layer:
Operating principle One virtual interface One MAC and one IP address
WLAN
MAC
ETH
MAC
Decision module
CL-MAC
CL-IP
COL-ACT-STA-
1 2 3 4 5 6 7 8 9101112HS1 HS2 OK1 OK2 PS
CONSOLE
1 Interface
1 Device
Gratuitous ARP
Switch
p. 15
BS = AP + extra functionality Extra WLAN NIC (passive)
listens to neighbor channel info per received Terminal
the MAC address a flag passive/active list with the last received RSSIs time of the last received packet IP address IP address of the BS RSSI per neighbor
Inter BS protocol Terminal info protocol
Horizontal handover
Details: horizontal handover
Vendor independent software packageRSSI of terminalmeasured on theserving BS
RSSI of terminalmeasured on theneighbor BSs, with their channels
Channel of the terminal
Sends beacons to the access network every X ms
Demo setup
BS X
TerminalAsterisk
Switch
A
AAP P
P
BS Z BS Y
Evaluation
• Sending 20Mb/s UDP with iPerf from server to terminal• Simulate motion handoff every 15 seconds→• Average of 15 lost packets per handoff• Lost packets ranged from 10 to 50 packets• 30 of the 37 handoffs less 14 lost packets→• Results in < 10ms disconnection time
1
2
3
4
5
6
X
Y
Z
A
PA
P
A
P
BS
BS
BS
Content
Switch
SB ATT 4:1 2:1
Terminalin SB
ATT 1-2
ATT 5-6
ATT 3-4
Attenuation
Time
Quality of Service onboard the train
BS
Provide QoS for Crew and Passenger applications
OSS
QoS AP with dynamic mapping of 5 Access Classes to 4 Access Queues
AP / Crew nodeAccess Queues:
• AQ_VO• AQ_VI• AQ_BE• AQ_BK
Access Classes:• Alarm • Voice• Video
• Best Effort• Background
Public nodeAccess Queues:
• AQ_VO• AQ_VI• AQ_BE• AQ_BK
ACCWmin[A
C]CWmax[A
C]AIFS[AC
]TXOP[A
C]Alarm 1 2 1 2048 ms
Voice 2 3 1 1504 ms
Video 3 4 2 3008 msBest Effort
4 10 3 2048 msBackgrou
nd4 10 7 0
EDCA parameters provided by QAP:
QoS results: Public and Crew Video, Downlink
Two Public video streams One Public and one Crew video stream
0
10
20
30
40
50
60
70
80
90
100
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181
time (s)
% o
f Max
imal
Thro
ughput
Public Video Traffic Stream Crew Video Traffic Stream
0
10
20
30
40
50
60
70
80
90
100
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171
Time (s)
% o
f Max
imal
Thro
ughput
Public Video Traffic Stream 1 Public Video Traffic Stream 2
AC_VI
AC_VI
AC_VI AC_VI
AC_VI
AC_VI AC_BE AC_VI
Conclusions
Onboard voice communication and multimedia have strict requirements Fast handover: new mechanisms developed QoS: dynamic class mappings
Layer 2 solutions for onboard network scope of onboard communication provider compatible with standard terminals
Q&A & Demo
