The objective of the study was to optimise the cost of delivering over satellite interactive services for direct-to-home broadcast (Interactive TV, iTV). The intended services are mainly interactive additions to broadcast programmes, and are thus located "below" interactive broadband services for example in terms of per-user data rate.
To achieve such a cost optimisation, the study has addressed commercial and technical characteristics of the services and the associated transmission and delivery schemes, as well as the costs of equipment and of space segment.
The study has addressed the global market for such services, with main emphasis on North America.
Interactive TV is much less developed in North America than for example in Europe; the main platform for consumer-oriented interactive services in North America remains the PC. Market and service demand predictions are correspondingly less reliable. There is no appropriate existing capacity for iTV services in North America. The study therefore sketched three different scenarios for dedicated and shared systems, ranging from "starter" systems to full-scale implementations.
Technically, it emerged that return link spectral efficiency was not a key driver; this was exploited to achieve cost reductions in the form of high power efficiency, nonlinear amplifiers and a simple access method.
The business case used a model centered on the service provider, in line with that prevailing for DTH services in North America. In this model, user installations are sold in combination with subscriptions (free-to-air programming is virtually non-existing). The business case demonstrated viability of the services with an ARPU of only a few dollars per month (excluding content).
The study has demonstrated the technical and financial viability of providing interactive TV services in North America. In the process of doing so, it has sketched suitable space segment arrangements and defined air interfaces and outline terminal requirements. The main remaining questions are the market prospects (which are difficult to predict due to the relative infancy of iTV services in North America), and the availability of investment capital.
Since no suitable space segment capacity is available in North America, a number of scenarios were investigated. They all used a spotbeam arrangement in Ka-band for the return link. Some took advantage of the new 18/25 GHz broadcast bands soon to become available in Region 2.
The transmission techniques are derived from those employed in DVB-RCS, the open standard for interactive satellite services. However, due to the modest requirements of the iTV services, very considerable simplifications could be achieved. The recommended air interface uses a turbo-coded, constant-envelope scheme (Turbo-GMSK) and Slotted Aloha access.
The user terminals were based on the Multimedia Home Platform (MHP) standard. This standard provides an adequate framework for the iTV services. The interactive outdoor unit was assumed to employ a nonlinear power amplifier.
The study first investigated the potential size of the market and the technical characteristics of the services. Subsequently, a joint design of air interface techniques, space segment, shared ground segment and user terminal was executed, with a view to minimising overall service provisioning cost. Finally, cost estimates for all elements were combined to produce a business case. This included a number of parameter variations.
The activity was started in May 2002. The technical activities have been completed in March 2003.