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Optimization of DATA Transmission for Transport SectorUser case, TMB
David LumbrerasProject Area Manager
In this presentation:
• User requirements• High efficiency in AVL Systems
– Comparing methods
• An example: TMB case
Fleet Manager Requirements:
Traffic Bus Regulation. Frequency Improvement. Customer Service. Investment Optimization. Passengers Safety
How to do it?
Voice Communications with the Control Centre. Half-duplex and duplex voice calls.
Status and short data transmission. Vehicle sensors transmission. MMI integrated on driver’s dashboard. Interaction with passenger information system. GPS-based location system.
How often is needed?
Data User Requirements: Continuous Actualization of Data in Control
Centre. Normally 20/ 30 second each Terminal.
User Requirements
Bus on-board equipment
Example: CONFIGURATION STRUCTURE
- PTT- Emergency button
- Call request
Passenger information
system
Audio interface
Bus driver’s audio system
Bus driver’s
MMI
control
PEI Telemetry sensors
Billing system
Other peripherals
engine, speed, doors...
Control unitControl unit
DISPLAYDISPLAY
data
Ambience listening
microphone
Hands-free audio kit
Handset
TETRA MSTETRA MS
Bus on-board equipment
Example: INSTALLATION DETAILS
Passenger Passenger information information
systemsystem
Micro speaker & Micro speaker & hands-free michands-free mic
TETRA TETRA radioradio
Driver’s MMI consoleDriver’s MMI console
Control unitControl unitBus system Bus system
interfaceinterface
Looking for the most efficient way for
DATA TRANSMISSION with TETRA
technology
• In this type of scenario it is necessary to analyse carefully the geographic positioning as the stronger requirement.
• Short Data Messages (SDS) comparing to Packet Data Protocol (PDP), the conclusions are:
With these conclusions, we are going to work with SDS polling to obtain the geographic positioning.
Nº slots
1 (MCCH)
2
3
4
Type of service
Ran
dom
PD
Polli
ng P
D
Ran
dom
SD
S
Polli
ng S
DS
MCCH Occupation
25%
50%
75%
100%
49%Scenario example
500 buses. 30 seconds of latency for all buses.20 bytes of information size.3 coverage sites (SBS).
High efficiency in AVL, Comparing Methods
• With the standard SDS procedure the requirement for the network is still strong.
• So now, it is necessary to think beyond the TETRA technology.
• New option improving the efficiency.
• Packets used in MCCH to transmit 20 bytes of data.
SwMiMobile in MCCH
ACK1/2 slot downlink SwMi acknowledge
Status REQUEST+ slot granting (1).D_STATUS_REQ1/2 slot downlink
Ack to Status + SDS data (160 bits)ACK + SDS_DATA1 slot uplink
System considerations.
Terminal considerations.
High efficiency in AVL, Comparing Methods
• New optimised polling SDS is the best solution to this type of application.
Nº slots
1 (MCCH)
2
3
4
Type of service
Ran
dom
PD
Polli
ng P
D
Ran
dom
SD
S
Polli
ng S
DS
MCCH Occupation
25%
50%
75%
100%
49%
Opt
imis
edPo
lling
SD
S
The
bes
t o
ne
Scenario example
500 buses. 30 seconds of latency for all buses.20 bytes of information size.3 coverage sites (SBS).
High efficiency in AVL, Comparing Methods
TMB User case
8 SBS´s
1300 buses
• With the best service selected…
Now it is necessary to think how we are going to synchronize the different CCHs.
Here using 1MCCH and 3 SCCH per SBS:• 15% of the control channel is used for geographic positioning.
To obtain this percentage it is necessary to synchronise all CCHs
Real scenario example
1300 buses. 20 seconds of latency for all buses.20 bytes of information size.8 coverage sites (SBS).
High efficiency in AVL, Comparing Methods
Synchronising the polling means...
...obtaining following figures:8 SBS x 4 CCHs = 24 CCHs to request the bus position
1300 buses / ( 20 seconds x 24 CCHs ) = 3 buses per second per CCH
Doing this polling is possible to obtain success with the application.
TMB user case, High efficiency in AVL
Synchronising the polling means...
The problem is:
External Application has not the capability to know where is located every bus in every second.
So for this reason Infrastructure manufacturers have to give the synchronism solution.
In that case the SwMi has to give to the applications provider several commands to introduce the buses to be polling, then…
..... polling answer will come from the SwMi Automatically.
TMB user case, High efficiency in AVL
Commands used by the application provider:
NEBULA
OUTPUT
COMMANDS User Application
List of commands needed to manage this application:
AVL-ADD-ISSIAVL-DEL-ISSIAVL-START-POLLINGAVL-STOP-POLLINGAVL-GET-POSITION
TMB user case, High efficiency in AVL
How the SwMi uses the ISSI list to poll at same time every CCH?
Real time operative system.
SwMi knows where all buses are placed so it can request them as same time with an internal table.
SBS1MCCH
SBS1SCCH1
SBS1SCCH2
SBS1SCCH3
SBS2MCCH …..
SBS8MCCH
SBS8SCCH1
SBS8SCCH2
SBS8SCCH3
70030 89903 34990 32122 08578 ….. 32890 38767 9009 348798439 33432 88998 83439 34343 ….. 34788 43433 34988 493834897 34676 34657 34686 34577 ….. 43789 43763 34876 34767
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .43677 34768 34566 34777 76667 ….. 36776 47767 3476 33344467 34553 33763 33 ….. 46673
33878 78898 3433 6676 ….. 4676634786 67763 ….. 6666787555 ….. 5346667657 ….. 53443
….. 34674
This three ISSI lines will be sent to poll the buses in one second
In 20 seconds all ISSIs on the table have to be sent to the
base stations to poll the complete buses fleet
TMB user case, High efficiency in AVL
Conclusions:
This solution can save around 60% of the channels in the network, with respect to the other alternatives
Only synchronized polling generated by the SwMi can manage with success this amount of data traffic
Thinking beyond the TETRA technology manufacturers can give to the customers the final solution
TMB user case, High efficiency in AVL
Optimization of DATA Transmission for Transport SectorUser case, TMB
Thank you for your attention
David LumbrerasProject Area Manager
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