Broadband communication network architecture with train control network and train serving network combined, and communication method thereof

A broadband communication network with a train control network and a train serving network combined, the broadband communication network, used for a data transmission in a combined network of the train control network and the train serving network, comprising a trusted network and an untrusted network;

• a data communication being performed between the trusted network and the untrusted network via a security gateway;
• wherein:
• the trusted network comprises a trusted carriage-level network element provided in each carriage, and in each of a front carriage and a last carriage, in addition to the trusted carriage-level network element, a trusted train-level network element is provided, the trusted carriage-level network element communicates with the trusted train-level network element;
• data transmitted in the trusted network comprises control data, monitored data and diagnostic information data in the train control network, and passenger information data and video information data in the train serving network;
• the untrusted network comprises untrusted train-level network elements respectively provided in the front carriage and the last carriage;
• one trusted train-level network element communicates with one untrusted train-level network element via a security gateway, and several security gateways are redundant to each other;
• the untrusted network is responsible for a connection between the train and a ground;
• data to be transmitted between the trusted network and the untrusted network is communicated bi-directionally between the trusted train-level network element and the untrusted train-level network element via a security gateway.