TLC TECHNOLOGICAL STANDPOINT
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Contents |
History
Historically satellites have been most successful in distributing information over very large
geographical areas using a single transmission. With services such as television broadcasting,
data broadcasting, digital messaging, enterprise virtual private networks (VPNs) and point-to-point
telecom-datacom services, traditional "bent-pipe" satellites have played a significant role in our
daily lives. A new generation of application needs, higher throughput requirements, and
communication demands are changing the way satellite systems are designed, implemented and
operated. New architectures and system networking concepts are being implemented to make
satellite systems capable of addressing these new market demands. The progressive idea of
making satellite systems that are optimized for highly in demand services (e.g., Internet access,
VPNs, personal access) opens entire new market opportunities that go far beyond the traditional
viewpoint of selling services only into markets that where satellite services excel (e.g.,
broadcasting, multicasting and content delivery).
To illustrate the wide variety of market needs and user expectations we've formulated a
service and market requirements matrix as presented in Table 1. As can be seen, there is a very
wide range of service capability, performance expectations and pricing. Thus the concept that one
system can address the diverse needs of the consumer, business and mobile marketplace is just
not realistic.
To be successful in any particular market segment (or even any two adjacent segments) the
system must be customized to meet the particular segment demands. For example, to provide
upstream data rates of 1 to 4 Mbps the satellite terminal needs to have a much larger antenna,
significantly more transmit power or the satellite must have a high G/T factor (e.g., spotbeam operation) than that for a consumer Internet access service capable of 64 to 256 Kbps. Another
example is that a $300 to $400 terminal price is incompatible with a 4 Mbps upstream transmit
speed. Direct peer-to-peer connections needed for enterprise networking applications (and
potentially future consumer applications) require mesh connectivity, not hub-spoke as in other
systems. Small dish, high-speed mesh connectivity is currently only achievable using specialized
on-board satellite processing techniques in conjunction with Ka-band spot beams.
From the service operator's (and investors') perspective, the business' return on investment
(ROI) must be attractive and compelling-service revenues need to be maximized and the
operational costs minimized. Take for example the first generation of satellite broadband service
(e.g., StarBand) that operates with upstream rates of 30 to 60 Kbps and much larger downstream
capacity (150 to 500 Kbps per user, 30 Mbps total capacity) to the user terminals that number
10,000 to 20,000 per transponder. However, system operational limits keep the number of
concurrent online users to below 8,000 per transponder. Yet the ROI economics for the service
provider require many more subscribers per transponder-and the end users demand much higher
data capacity as interactive broadband applications and services become more widespread. [1]
What does broadband satellite really mean?
Broadband satellite systems both receive and transmit rich-media content to and among
network end-users whether at home or in the office-these systems are not intended to supply
huge amounts of bandwidth for backbone infrastructure purposes. The market need is great for
two-way broadband network access across large geographical areas where infrastructure has not
been built out, or would be too costly to implement. In short, satellite will become the broadband
"local-loop" in such communities.
Forecasted broadband satellite service revenues are projected in Figure 1 over the next eight
years, growing from $2.2B this year to over $40B and contribute 30 percent of broadband service
revenues worldwide. Thus, there is considerable economic motivation for today's heavy investment
in next-generation broadband satellite systems by a number of players. [1]
Status
The emerging satellite communication constellations differ substantially from prior generations of systems. For years, satellite
systems have offered broadcast and interactive services, but with major limitations. The new generation of services promise to
overcome the traditional barriers, such as terminal weight and size, equipment and service cost, and degree of mobility. Instead,
the new systems will provide completely new capabilities which expand the flexibility for the user and the range of potential
applications. However, the introduction of such a “next-generation” communications system is often plagued by difficulties in
forecasting market demand, as customer themselves may not accurately forecast their own needs for such services.
The global information infrastructure (GII) is
undergoing tremendous change as demand for Economics of broadband satellite services|broadband communications services continues to outstrip supply.
While a number of new ventures will attempt to fulfill
that demand by greatly increasing transoceanic fiber network
capacity, there is substantial doubt that wireline
facilities alone will be both adequate and technically and
financially feasible for providing the total bandwidth
required to sustain the GII. Satellite networks are already
playing a role in supporting the bandwidth demands of
the Internet as a backbone system, through such
enterprises as SkyCache. Other satellite service providers
such as Comsat provide bandwidth on demand to
major landline carriers to provide redundancy for wireline
networks or to supplement available bandwidth.
However, an emerging generation of satellite systems
now promise to act as a primary carrier of interactive
broadband services, putting new demands both on satellite
technology and enabling the provision of new applications.
Incumbent satellite communications systems are optimized
to support three primary markets:
- Large enterprise customers, who use such services as Very Small Aperture Terminal or VSAT data communications and live television broadcasting (for television networks and corporate videoconferencing);
- Telecommunications carriers, who purchase wholesale telecommunications capacity for long-haul voice and data service; and
- Consumer households, who became major satellite service customers after the introduction of direct-to-home or direct-broadcast-satellite (DBS) television services in the 1990s.
They are primarily used to transmit between two fixed locations, due to the size and expense of ground station equipment (the exception being DBS, which is a point-to-multipoint service). In place of the current generation of systems, private companies are now launching new satellite communication systems which provide mobile rather than fixed communication services (Dornan, 1999). This new generation of systems are notable primarily for their use of low-earth-orbit (LEO) architectures, instead of the conventional geosynchronous (GEO) orbit configuration. Since the number of GEO orbit slots is limited, and signal latency to and from the GEO orbit is significant, LEO systems provide also superior performance in terms of signal quality and latency, terminal size, and availability of orbital slots. Other systems use mid-earth-orbit (MEO) architectures, or in some cases hybrid GEO-LEO and MEO-LEO configurations (see Table 2). [2]
Future trends and expected technological evolution
Two factors, epoch of the service start and
cost of the satellite, are picked up for consideration
of the future satellite. It is known that the
LEO mobile communications satellite is not
cost-competitive due to the surprised penetration
speed of the terrestrial cellular phones. On the
other hand, it is described that the broadcasting
satellite service is very cost-competitive to the
terrestrial broadcasting service.
Second, the cost-competitiveness of the futnre
communication satellite is examined in terms of
the cost and length of time to be developed. The
future satellite is based on a model of the future
communications satellite for next 30 years
which has been proposed. The satellite cost of
the 60-120 Gbps range of capacity, which is
called as a second generation communications
satellite, is estimated. It is shown that the second
generation communications satellite will be costcompetitive
in comparison with the terrestrial
system. It is also described that the third generation
communications satellite is more costcompetitive.
As far as the length of time for development
is concerned, it is described that the
small satellite is useful to develop the key technology. [3]
Factors defining cost - Competitiveness
Whether or not a satellite communications system is realized successfully depends on how its cost is competitive in comparison with other systems. In this chapter, the factors which define the cost-competitiveness are discussed. For the operational services, the cost-competitiveness means just less expensive than other systems. For the only one service system, it is important that the satellite communication service is started as soon as possible.
Cost-Competitiveness of mobile satellite
One of the factors which determine the cost-competitiveness is how the service can be provided at the optimal time. Further, the success of the mobile satellite communications system depends on how early and user friendly terminal to be developed.
Cost-Competitiveness of broadcasting satellite
It is said that the satellite broadcasting is very costcompetitive to the terrestrial broadcasting service. For example, the operation cost per year per household by the satellite broadcasting system is only one-fourth as much as the terrestrial broadcasting system. [3]
Cost of future communications satellite
The cost of the future communication satellite is discussed in this chapter. The purpose of the discussion is to examine whether or not the future communications satellite has cost-competitiveness.
Three generations approach of future communications satellite
The need of communications satellite will be unchanged in the future, because of the feature of satellite communications’. Considering the necessity of satellite communications in the future, three generations of communications satellites were proposed.
Cost estimation of the future communications satellite
The cost of a 2G satellite is estimated, considering the cost of bus, the cost of mission equipment and the development cost.
Consideration of cost-trend
In this section is shown the approximate cost trend of the communications satellite, with particular attention to the cost vs. generation power and the cost vs. capacity of the satellite.
Effective development for long time development
One of the barriers that the satellite communications system must cope is how to provide the services at the optimal time. It takes a long time to develop a satellite communications system, especially a satellite to develop new technologies with R&D. [3]
References
[1] M.Dankberg, J.Puetz
"Comparative approaches in the economics of broadband satellite services".
[2] E.G.Carayannis, J.Alexander
"Virtual, wireless mannah: a co-opetitive analysis of the broadband satellite industry".
[3] T.Iida
"Cost consideration for future communications satellite".
