A method and device for communicating in a contention-based communication network. The method includes upon an early termination of a previously obtained transmission opportunity (TXOP) for communications with one of a mobile device and a base station, transmitting a contention free end (CF-End) frame to the base station for further broadcasting to the network by the base station. Also, a method and device for communicating in a contention-based communication system. The method includes receiving in a base station a first contention free end (CF-End) frame from a first mobile device indicating an early termination of a transmission opportunity (TXOP) previously obtained by the first mobile terminal for communications between the first mobile device and one of the base station and a second mobile device; and omnidirectionally broadcasting a second CF-End frame with a duration field having a value equal to zero.