Добавил:
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
курсач / материалы / es_201980v040102p.pdf
Скачиваний:
0
Добавлен:
13.05.2026
Размер:
1.25 Mб
Скачать

78

ETSI ES 201 980 V4.1.2 (2017-04)

When the Time and date data entity or announcement support and switching data entity is included in the SDC, and alternative frequencies are signalled, then a semi-dynamic use of the SDC is recommended. In this case one or more SDC blocks in the cycle defined by the AFS index are signalled to be invalid by use of the FAC Identity field thereby allowing the content of those blocks to be changed continuously, whilst other SDC blocks are always signalled as valid by use of the FAC Identity field thereby allowing the AFS function to be performed. An example of changing the SDC content and of using the semi-dynamic scheme with the AFS index = 1 is given in annex G.

A change of the AFS index is only allowed at reconfiguration.

6.4.6Signalling of reconfigurations

6.4.6.0Introduction

The DRM Multiplex may be reconfigured at transmission super frame boundaries.

Reconfiguration of the DRM multiplex shall be signalled in advance in order to permit receivers to make the best decisions about how to handle the changes. There are two types of reconfiguration: a service reconfiguration, which concerns the reallocation of the data capacity between the services of the MSC, changes in the MSC protection level or changes in the source coding or data applications; and a channel reconfiguration, which concerns changes to the channel parameters or robustness mode.

Both types of reconfiguration are signalled by setting the FAC reconfiguration index to a non-zero value. The index then counts down on each subsequent transmission super frame. The reconfiguration index shall be identical for all transmission frames of a transmission super frame. The final transmission super frame corresponding to the current configuration shall be that in which the reconfiguration index = 1. The new configuration takes effect for the next transmission super frame and in which the reconfiguration index = 0.

All data entity types that use the reconfiguration mechanism for the version flag that are present in the current configuration, and all data entity types that use the reconfiguration mechanism for the version flag that are required in the new configuration, shall be sent during the period when the reconfiguration index is non-zero with the version flag indicating the next configuration. This shall include data entity type 10 that signals the FAC channel parameters for the new configuration.

6.4.6.1Service reconfigurations

A service reconfiguration is one in which the data capacity of the MSC is reallocated between services. This happens when the number of services in the multiplex is changed or the size of data streams is changed. A service reconfiguration shall also be signalled if any of the content of the data entity types using the reconfiguration mechanism of the version flag changes. The reconfiguration shall be signalled as far in advance as possible in order to provide the greatest chance that the receiver gets all the information necessary for the next configuration. Therefore the reconfiguration index shall first take the value 7. In most cases the receiver can follow service reconfigurations without interruption to the audio (see annex Q).

When a new service is introduced, and the overall capacity of the MSC is not changed, then the receiver shall follow the currently selected service through the reconfiguration. To facilitate this, the Service identifier and Short Id of all continuing services shall remain the same. The new service shall use a Short Id that is not used in the current configuration. The one exception to this rule is if there are four services in the current configuration and four services in the new configuration. In this case, if the currently selected service is discontinued, then the receiver follows to the new service with the same Short Id if it is of the same type (e.g. both are audio services).

If the currently selected service is discontinued at the reconfiguration, then the receiver may try to find another source of that service on another frequency and/or system by using the information from data entity types 3 and 11.

ETSI

Соседние файлы в папке материалы