An architecture design approach for large satellite networks

Designing a world-wide satellite network that consists of hundreds of user sites and thousands of circuit connections is a complex problem, which involves selecting a set of candidate satellites and satellite beams/frequency bands from among numerous existing and planned satellites, evaluation of circuit connectivity, earth-station compatibility and sizing, and estimating transponder loading. The design process may also require assessment of the impact of a different set of satellites and modified user traffic requirements on the space segment, the earth-station types and quantity, and the total system cost. Although a conventional design approach based on link-by-link and site-by-site analysis provides accurate results, it is time-consuming and impractical for developing high-level network architectures in a time-constrained environment. A design technique is proposed which employs a set of rules for satellite network design, in combination with extensive databases of satellite parameters, earth-station parameters and user traffic requirements, to synthesize a network architecture. The technique is particularly useful for performing high-level trade-offs among alternative architectures in terms of space segment requirements, the number and type of earth-stations and overall system cost. Once the desired architecture has been selected, a detailed design may be developed using conventional methods.     

VSAT networks in the intelsat system

This paper describes how VSAT networks currently operate in the INTELSAT system. Four classes of VSAT networks (data transaction; circuit-switched; data distribution; microterminals) are identified, and it is verified that all of them can operate with INTELSAT satellites. Most VSAT networks in operation on INTELSAT today operate in fractional transponder leases. Fractional transponder capacity estimates are presented for a wide range of scenarios and different INTELSAT satellite series. These estimates clearly show increasing bandwidth utilization efficiencies for newer generations of INTELSAT satellites. Provided that VSAT and hub sizes are appropriately selected, efficiencies are already significant with existing satellites. Two possible ways of increasing the utilization of satellite resources are examined in the paper: demand assignment multiple access (DAMA) and multiple channel-per-carrier (MCPC) techniques. The impact of using DAMA in circuit-switched VSAT networks is quantified.     

The intelsat VIII/VIIIA generation of global communication satellites

Developed originally to meet increased demand forecast for C-band capacity in the Pacific Ocean Region (POR), this latest generation of INTELSAT satellites is planned to be operated in a number of traditional and new roles. To date INTELSAT has bought four INTELSAT VIII spacecraft for Pacific, Indian and Atlantic Ocean regions and two modified VIII-A to meet the specific Landmass requirements for the rapidly expanding Asia-Pacific and pan-American market. The VIII spacecraft, using Martin Marietta Astro Space's GS7000 bus has sufficient power and payload carrying capability that it can accommodate a wide variety of services. A new feature for INTELSAT is the inclusion of arcjet propulsion which has the potential for long lifetime while needing only half of the fuel requirement of conventional thrusters. This new high power satellite will form a key part of the INTELSAT global network through to the year 2010 and complement the INTELSAT VII and VIIA series.     

The TNS program: A computer simulation package for the intelsat TDMA network

The TNS (TDMA Network Simulation) program is a computer simulation package developed for the evaluation, test and analysis of all the protocols in the INTELSAT TDMA network. The TNS program faithfully simulates the dynamic operation of the network, taking account of the satellite motion, and makes it even possible to simulate the network operation under some abnormal conditions, such as terminal function failure and transponder failure. This paper describes the TNS program in terms of its design approach, its capabilities, its structure, its input and output data, and its operation. An example simulation for the whole system start-up procedure assuming the Atlantic Ocean region is also presented.