In this section we present a few articles and applications regarding studies
over the VSAT network and also some software tools we found.
1. A Simulation Study of a Broadband Multimedia VSAT network
- is a simulation approach for assessment of quality of service and bandwidth
utilisation for a meshed broadband VSAT system over a geostationary satellite. u4l8lo
- A multi-frequency timedivision multiple access is used (MF_TDMA) with an integrated
call admission control (CAC) and bandwidth on demand (BOD) algorithm for uplink
from the VSATs.
- Traffic source models of variation multimedia services are implemented along
with the CAC and BOD scheme using OPNET. Using this simulation platform, we
measure the quality of service for different applications and uplink bandwidth
utilization.
- After extensive simulation experiment for various traffic mixes, the results
refer to uplink throughput, SIT queing delay and end-to-end queing delai.
- Based on the results several issues can be effectively addressed. For example,
the system designers can determine how to mix different applications to obtain
maximum capacity utilization network revenue, guarantee the QoS for all applications
with limited network resources, and implement buffers of sufficient size to
reduce loss.
2. Optimal resource Utilisation in VSAT Networks
- Provides optimal resource utilization for various traffic streams in VSAT
networks.
- Presents various types of traffic such as bursty, demand based traffic and
multimedia traffic and worked on the problem of optimal utilization of the satellite
bandwidth under various traffic conditions. A GUI oriented discrete-event simulator
in Visual C++, is decvelopped and implemented many MAC layer protocols like
ALOHA, R-ALOHA, FDMA, TDMA, frequency hopping and their combinations for simulation
and study of various scenarios.
- An ALOHA protocol simulator written in Visual C++. All the parameters are
adjustable and it shows the packets animation in real-time.
- A Visual MAC Simulator was that automatically does bandwidth utilization
analysis and outputs a report file. Sources can be configured and any number
can be added. It supports many different kinds of sources and also many different
MAC protocols like Aloha, FDMA, TDMA, FTDMA etc. It activates the sources and
records actual bandwidth utilization. Purpose was to find efficient ways of
bandwidth utilization in VSAT networks.
- There are also available some graphs generated by the simulator with some
of the MAC protocols we tried.
3. Digisim 3.0 Satellite Communications Software
- DIGISIM can help planning for new satellite digital transmission services,
preserving link quality of existing services and supporting spectrum coordination
processes.
- DIGISIM can serve satellite operators, teleports, VSAT-operators etc., in
areas as diverse as link analysis, transmission planning, system engineering,
systems architecture, spectrum coordination, interference control, and more.
- DIGISIM is a time-domain simulation tool, simultaneously generating up to
3 modulated carriers, passed through individual satellite transponders or sharing
one transponder. Each carrier can be independently configured for offset frequency,
symbol rate and modulation type. Supported modulation formats are QPSK, Offset-QPSK,
BPSK, 8-PSK and 16-QAM. Roll-off factor of pulse-shaping filters can be independently
set for transmitter and receiver. Automatic receiver clock synchronisation can
be overridden by manual control. Additional carriers can be added to create
a desired interference or inter-modulation scenario. Each transponder can be
individually configured with user-supplied filter and (TWT-)nonlinearity response
files. The built-in filter set-up algorithm performs GD-to-phase conversion
and re-interpolation necessary for filter computation. Transponder input back-off
and relative output levels are individually adjustable. Multipath interference
from adjacent uplinks is included by default, can be disabled. Dynamic uplink
pre-distortion can be individually enabled to compensate for Imux-, TWT- and/or
Omux-responses of each active transponder. Carrier phase noise can be enabled,
combining cascaded contributor spectra (up-converter, on-board LO, LNB) read
from file. Phase noise spectrum can also be manually entered as discrete points
on a logarithmic scale, and stored to file if desired. Result of each simulation
run is presented as a Symbol-Error-Rate(SER)-curve plotted against Eb/N0, Es/N0,
C/N in Nyquist bandwidth or user bit rate. Multiple SER-curves can be overlaid,
edited and annotated for comparison between runs. Waveform plots (constellation
plot, output spectrum, eye-diagram, I/Q waveform plot), as well as possibly
generated phase noise spectrum plots can be called from menu functions. The
computed output spectrum can be exported to file. The user interface is fully
GUI-based, facilitating parameter entry and file loading.
- It is not a freeware software.
References :
· “Simulation Study for a Broadband Multimedia VSAT Network”
-; Yi Qian, Rose Hu and Hosame Abu-Amara
· “Optimal Resource Utilisation in VSAT Networks” -;
AshishGupta https://www.cs.northwestern.edu/Iagupta/_projects/visual_mac_simulator/
· https://www.ses-astra.com/corpSite/site_en/SupportServices/TechCom/index.php
· https://www.angelfire.com/electronic/vikram/tech/vsattut.html#1
· https://www.comsys.co.uk/vsat_rep.htm
· https://www.telesat.ca/telecom/anikomVSAT.htm
· https://www.qpcomm.com/vsat_info.html
· https://www.satcoms.org.uk/vsat/vsat_tutorial.asp
· https://www.telekom.com.my/business/corporate_government/data_services/vsat_faq.htm#01
