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QoS over Demand-assigned
TDMA Satellite Network
Presenter:
Mr Pang Yoke Kum
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Project Participants
1.Temasek Polytechnic
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Mr
Mr
Mr
Mr
SRINIVASAN SUKUMAR
PANG YOKE KUM
TEDDY RUSMIN
LOH YEOW MENG
2.Nanyang Technological University
Assoc
Prof. K R SUBRAMANIAM
3.Laboratories for Information Technology
DR
CHENG HENG SENG
Project funded by SINGAREN
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DA-TDMA - Introduction
Why DA-TDMA satellite network?
To efficiently allocate satellite bandwidth to remote VSATs
on demend.
Every remote VSAT transmits its carrier burst at the
same bandwidth and same frequency, but not at the
same time.
Every remote VSAT is not pre-assigned to transmit its
carrier burst within a specific time slot.
Each remote VSAT is allocated a fixed percentage of
satellite bandwidth (time slots).
There is a certain percentage of satellite bandwidth
which can be dynamically allocated to remote VSATs
basing on users’ demands.
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DA-TDMA - Issues
Time delay related issue
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When dynamically assigned satellite bandwidth to
remote VSATs, it imposes a certain amount of delay.
(Eg. Time delay during the change of modem
parameters). Such delay has an impact of the QoS
on various applications.
Channel error related issue
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With same transmit power, an change of satellite
bandwidth allocation causes a change of BER at the
receiving VSATs. Such change of BER has an impact
of the Qos on various applications.
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Project Objectives
To contribute to the study of DA-TDMA based satellite
networks in terms of providing research findings to
the research community in this field of study on :
(a) the effectiveness of QoS over the DA-TDMA
satellite networks and
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(b) the impact of channel errors over the DA-TDMA
satellite networks
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Introduction to a Star Shape DA-TDMA
Satellite Network
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Network Characteristics
1.
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3.
TDM outbound
TDMA inbound
Bandwidth on Demand
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Main Considerations In Implementing a
DA-TDMA Satellite Network
1)
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4)
Satellite bandwidth required.
Choice of satellite modem.
Ensuring a sufficient energy-per-bit-to-noise
density ratio (Eb/No).
Internet Protocol. (IPv4 and IPv6)
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Locations of VSAT Earth Station
1) Temasek Polytechnic, Singapore
2) Nanyang Technological University,
Singapore
3) University of Science Malaysia,
Malaysia
4) University Putra Malaysia, Malaysia
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Proposed Star Shape DA-TDMA Satellite Network
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Infrastructure Setup (ODU)
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RFT
Radio
Frequency
Transceiver
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Infrastructure Setup (ODU)
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SSPA
Solid
State
Power
Amplifier
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Infrastructure Setup (ODU)
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Feedhorn
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Infrastructure Setup (ODU)
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2.4m Dish
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Infrastructure Setup (IDU)
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Modem/Router
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Infrastructure Setup (IDU)
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Network Management System
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Proposed Tests
Impact of Bandwidth on Demand (BoD)
on QoS.
 Impact of Satellite Propagation Delays
on QoS.
 Performance Evaluation for IPv4 and
IPv6 Networks.
 QoS for several applications
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The OSI Layers
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Layer
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6
5
4
3
2
1
Application
Presentation
Session
Transport
Network
Data Link
Physical
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Test Methodology
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QoS at physical layer
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1) Transmit RF carrier at different transmit power levels
(within the permitted range) at the Hub modem and record
the BER and Eb/No values at the Remote modem.
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2) Plot the BER against Eb/No graph so as to determine
the range of Eb/No values, to be used for the testing of the
impact of channel errors over the DA-TDMA satellite
networks at Layer 3 (Network Layer).
• Transmission media
• Wireless
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Test Methodology
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QoS at data link layer
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With transmission of different data size from
remote to hub at different transmission rate,
measure the channel utilisation of the data link
and optimise the channel allocation for different
data traffic (NMS).
• Medium Access Control
• TDM (outbound)
• TDMA (inbound)
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Test Methodology
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QoS at network layer
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Tests under IPv4 and IPv6 platforms will be
performed. Only the necessary routes are added to
the routing table.
• Protocol
• IPv4
• IPv6
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Test Methodology
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QoS at transport layer
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For best performance, the buffer sizes on routers
and switches have to be adjusted.
• Protocol
• TCP
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Test Methodology
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QoS at application layer
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For best performance, OS window size has to be
adjusted.
• Applications
• Video-conferencing
• Data Transfer
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Schedule
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Work accomplished
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ODU and IDU set-up at TP
Completed satellite loopback test at TP
Collected BER and Eb/No data at TP
Work in progress
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Set up modems at USM and UPM
Establish satellite links with USM and UPM
Setup of IPv6 network
Measure network performance
Video conferencing
Set up Mobile IP system
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Thank you !
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