Time division duplex orthogonal frequency division multiplexing distributed antenna system, base station and remote access unit

A base station of a time division duplex orthogonal frequency division multiplexing distributed antenna system (TDD-OFDM DAS), the base station using a transmission band comprising a used band subcarrier set and a guard band subcarrier set, the base station comprising:

• a signal processing circuit, being configured to perform an inverse fast Fourier transform on a user downlink signal, a transmitting/receiving enable signal and an input control signal to generate a first OFDM signal, the user downlink signal being carried on the used subcarrier set of the first OFDM signal, and the transmitting/receiving enable signal and the input control signal being carried on the guard band subcarrier set of the first OFDM signal;
• and
• a fiber transceiver, being electrically connected to the signal processing circuit and being connected to a remote access unit (RAU) via a fiber transmission line, and being configured to transmit the first OFDM signal to the RAU via the fiber transmission line, so that the RAU filters the transmitting/receiving enable signal and the input control signal carried on the guard band subcarrier set of the first OFDM signal to generate a second OFDM signal, retrieves the transmitting/receiving enable signal and the input control signal from the guard band subcarrier set of the first OFDM signal, switches between a transmitting mode and a receiving mode periodically according to the transmitting/receiving enable signal, transmits the second OFDM signal to a user device in the transmitting mode, performs a clock synchronization with the base station according to the transmitting/receiving enable signal, and performs a system configuration according to the input control signal.

A remote access unit (RAU) of a time division duplex orthogonal frequency division multiplexing distributed antenna system (TDD-OFDM DAS) using a transmission band comprising a used band subcarrier set and a guard band subcarrier set, the RAU comprising:

• a fiber transceiver, being connected to a base station via a fiber transmission line and being configured to receive the first OFDM signal from the base station via the fiber transmission line, the base station performing an inverse fast Fourier transform on a user downlink signal, a transmitting/receiving enable signal and an input control signal to generate the first OFDM signal, the user downlink signal being carried on the used subcarrier set of the first OFDM signal, and the transmitting/receiving enable signal and the input control signal being carried on the guard band subcarrier set of the first OFDM signal;
• an RF transceiver, being electrically connected to the fiber transceiver and being configured to filter the transmitting/receiving enable signal and the input control signal carried on the guard band subcarrier set in the first OFDM signal to generate a second OFDM signal;
• a frequency division multiplexing bandpass filter bank, being electrically connected to the fiber transceiver and being configured to retrieve the transmitting/receiving enable signal and the input control signal from the guard band subcarrier set of the first OFDM signal;
• a synchronization circuit, being electrically connected to the frequency division multiplexing bandpass filter bank and being configured to perform a clock synchronization with the base station according to the transmitting/receiving enable signal;
• and
• a control circuit, being electrically connected to the frequency division multiplexing bandpass filter bank and being configured to perform a system configuration according to the input control signal, switch between a transmitting mode and a receiving mode periodically according to the transmitting/receiving enable signal and transmit the second OFDM signal to a user device in the transmitting mode.