**4.2.2 Priority application communication requests management**

The broadband communication platform enables train and terrestrial railway applications to communicate each other. So when an application attempts to start a new communication makes a communication request to the platform. Then the system make a decision about what priority requests can be served concurrently by the system taking into account active link bandwidth limitations and requests QoS requirements.

On the train side, the OCM must be able to prioritize communication requests made by the on board applications. So, the OCM queues train applications' requests in base of established prioritization criteria. Then taking into account communication active link bandwidth properties, the OCM notifies to TCM about the on board most priority requests that could be served concurrently by the system respecting these requests QoS requirements. TCM will ultimately decide and notify the OCM which communications can be addressed at every moment, considering the rest of the terrestrial applications' request.

Therefore, on the ground side the TCM will manage terrestrial applications' requests as OCM do in the train. Besides, TCM will have a queue for each train on the system containing that train's requests (notified by its OCM) and terrestrial requests in order to make decisions about what applications' requests can communicate at every moment.
