A method for providing two-way communication between a communications device (11, 12, 13) and a plurality of users based on an orthogonal frequency division multiplexing Time Division Multiple Access, OFDM-TDMA, two-way service, comprising: assigning, by means of the communications device, timeslots in a TDMA frame structure to multiple users in a TDMA manner, so that each user has a different timeslot; and in each timeslot: simultaneously sending a local-end OFDM signal from the communications device to user equipment of the user to whom the timeslot is assigned, and receiving said remote-end OFDM signal by the communications device, so that the timeslot is simultaneously used for uplink and downlink communication between the communications device and said user equipment; and cancelling, by means of the communications device, in an overlapped spectrum duplex, OSD, manner, interference caused by an echo OFDM signal, which is produced according to the local-end OFDM signal, to the remote-end OFDM signal, wherein a spectrum of the echo OFDM signal and a spectrum of the remote-end OFDM signal overlap, characterized in that the cancelling is performed in a digital signal frequency domain cancellation manner and comprises: obtaining, according to the echo OFDM signal produced by the local-end OFDM signal, and the remote-end OFDM signal, a phase difference between the echo OFDM signal and the remote-end OFDM signal and a channel transfer function of an echo path; generating an echo cancellation OFDM signal according to the phase difference, the channel transfer function of the echo path, and the local-end OFDM signal; and subtracting the echo cancellation OFDM signal from received signals, to cancel the echo OFDM signal in the received signals, wherein the received signals comprise the echo OFDM signal and the remote-end OFDM signal. assigning, by means of the communications device, timeslots in a TDMA frame structure to multiple users in a TDMA manner, so that each user has a different timeslot; and in each timeslot: simultaneously sending a local-end OFDM signal from the communications device to user equipment of the user to whom the timeslot is assigned, and receiving said remote-end OFDM signal by the communications device, so that the timeslot is simultaneously used for uplink and downlink communication between the communications device and said user equipment; and cancelling, by means of the communications device, in an overlapped spectrum duplex, OSD, manner, interference caused by an echo OFDM signal, which is produced according to the local-end OFDM signal, to the remote-end OFDM signal, wherein a spectrum of the echo OFDM signal and a spectrum of the remote-end OFDM signal overlap, simultaneously sending a local-end OFDM signal from the communications device to user equipment of the user to whom the timeslot is assigned, and receiving said remote-end OFDM signal by the communications device, so that the timeslot is simultaneously used for uplink and downlink communication between the communications device and said user equipment; and cancelling, by means of the communications device, in an overlapped spectrum duplex, OSD, manner, interference caused by an echo OFDM signal, which is produced according to the local-end OFDM signal, to the remote-end OFDM signal, wherein a spectrum of the echo OFDM signal and a spectrum of the remote-end OFDM signal overlap, characterized in that the cancelling is performed in a digital signal frequency domain cancellation manner and comprises: obtaining, according to the echo OFDM signal produced by the local-end OFDM signal, and the remote-end OFDM signal, a phase difference between the echo OFDM signal and the remote-end OFDM signal and a channel transfer function of an echo path; generating an echo cancellation OFDM signal according to the phase difference, the channel transfer function of the echo path, and the local-end OFDM signal; and subtracting the echo cancellation OFDM signal from received signals, to cancel the echo OFDM signal in the received signals, wherein the received signals comprise the echo OFDM signal and the remote-end OFDM signal. obtaining, according to the echo OFDM signal produced by the local-end OFDM signal, and the remote-end OFDM signal, a phase difference between the echo OFDM signal and the remote-end OFDM signal and a channel transfer function of an echo path; generating an echo cancellation OFDM signal according to the phase difference, the channel transfer function of the echo path, and the local-end OFDM signal; and subtracting the echo cancellation OFDM signal from received signals, to cancel the echo OFDM signal in the received signals, wherein the received signals comprise the echo OFDM signal and the remote-end OFDM signal.