Achieving Stable Transmission on VSAT Networks

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Achieving Stable Transmission on VSAT Networks
Sameer Sahasrabudhe Saraswathi Krithivasan
Malathy Baru
Case Study Distance Education Program (DEP),
IIT Bombay
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Introduction

• Distance Education Program is now Satellite
  Transmission Unit under the Centre for Distance
  Engineering Education Programme, of IIT Bombay.

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Outline

• Introduction
• Network Setup
• Working Model
• Factors Affecting transmission
• Atmospheric
• Rain Fade, Sun outage
• Terrestrial
• Hardware, Software failures, Human Error
• Conclusions

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Introduction Network Setup
Uplink Center at IITB
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Introduction Working Model

• Uplink Center at IITB, starts multicast

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Introduction Working Model

• Uplink Center at IITB, starts multicast
• Multiple audio-video feeds from the classroom get
  encoded

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Introduction Working Model

• Uplink Center at IITB, starts multicast
• Multiple audio-video feeds from the classroom get
  encoded
• Two bandwidth channels for transmission-
• 512 kbps, data channel (DAMA)
• 16 kbps, control channel (TDMA)

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Introduction Working Model

• Remote Centers (RCs) receive the lecture and is
  projected on a screen for the participants.

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Introduction Working Model

• Remote Center (RC) uses the 16 kbps control
  channel to ask for the floor request
• 512 kbps data channel is allocated to the RC from
  IITB
• Re-allocated to IITB after the question is over

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Factors affecting transmission
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Factors affecting transmission

• Atmospheric
• Rain fadeLoss of signal due to increased sky
  noisetemperature caused by heavy rainfall
• Regulated with Automatic Uplink Power Controller
  (AUPC)
• Sun outage
• Noise from Sun overrides signals from Satellite
• ISRO announcements

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Factors affecting transmission

• Terrestrial
• Hardware
• Complexity of the network setup
• Restoring connectivity within threshold
• Hot-swappable redundancy
• Constant monitoring

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Factors affecting transmission

• Terrestrial
• Software
• Multiple Operating Software
• Closed User Group (CUG) access
• Network Management System
• Standardizing software configurations across RCs

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Factors affecting transmission

• Human Errors Minimize human errors to maintain
  uniform quality learning environment
• Training technicians
• Documenting procedures
• Reviewing RC Setup
• Standardizing equipment
• Maintaining Protocols

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Conclusions

• Improving quality of transmission
• Streamlining procedures
• Increasing participants

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• Thank You !