Data transmission method, system, sending terminal node and receiving terminal node

The invention provides a data transmission method, a system, a sender node and a receiver node thereof. During a time slot i allocated to the sender node, the sender node sends an RTS message in the RTS(transmit requires) period; if an NTS message is received in the NTS period of the time slot i, the step of sending an RTS message is turned to in the next time slot j allocated to the sender node;otherwise, service data is sent in the DATA period of the time slot i. As for the receiver node, if the RTS message is not received successfully in the RTS period of the time slot i, the NTS message is sent in the NTS period of the time slot i and the sender node is forbidden to send the service data during the time slot i; and if the RTS message is successfully received in RTS period, no NTS message is sent in the NTS period of the time slot i. The method and the system can realize the harmonious transmission of broadcasting and unicasting service data.