scope:

This European Telecommunication Standard (ETS) establishes a broadcasting standard of a System for Wireless Infotainment Forwarding and Teledistribution (SWIFT) designed for delivery of data services for mobile, portable and fixed receivers in the FM band. This ETS defines the nature and content of the transmitted SWIFT signal. It describes also the organization of the multiplex for the SWIFT standard.

A multiplex is necessary to optimize the use of the radio channel by sharing it between several applications. For example, a dGPS application has some precise constraints such as real time (one message per second), size (2 kbits per message). This application requires a continuous channel of perhaps 3 kbit/s. Assuming a DARC channel has a minimum useful bit rate of 6 kbit/s, it would be interesting to use the remaining 3 kbit/s for an other application, newspapers broadcasting for example.

On the opposite, in a newspaper application, it is necessary to broadcast the news twice a day for example in a maximum time (1 hour). This is a low rate service with a big amount of data and without real time. It would be interesting to stop for some time this service if hot news have to be sent (higher service priority).

Sometimes, the network operator can offer the same application (class of application/service) to different service providers, for example, different newspapers. It would be interesting to multiplex this newspapers on the same radio channel in a transparent manner for the service provider point of view.

The multiplex can be made:

- in the Transmitter Station Equipment (TSE), for splitting the radio channel into logical channels using a given mapping at a given time. The characteristic of the logical channels is a constant bit rate enabling real time applications and/or applications requiring constant bit rate all the time;

- in the TSE, for repeating regularly or inserting some information into the multiplex. In this case, a local priority management is required;

- on the network server, based on a priority mechanism. This enables for example the mixing of several applications with different priorities, but not real time and on demand (news and hot news, pictures preloading and weather information);

- on the network server, for multiplexing different processes of an application (for example, different newspapers for the application newspapers broadcasting). This is useful if it should offer a quicker "average" service (for example, the reading of a newspaper page by page before the complete loading).

As described above, there are different multiplexing levels/functions for different reasons. Each function is necessary and it shall be possible to make them running together.