Base station, communication system and time synchronization method between base stations

A base station comprising:

• a radio communication section capable of performing a downlink signal transmission of an OFDM (Orthogonal Frequency Division Multiplexing) system to a mobile station;
• and
• a transmission timing control section of controlling a transmission timing for the mobile station, and
• wherein an own cell is located in a cell of another base station capable of performing a downlink signal transmission of the OFDM system to a mobile station, and
• wherein the transmission timing control section controls so as to stop a downlink signal transmission with respect to a predetermined subframe in which a downlink wraparound signal from the own base station interferes with a synchronization signal of the other base station, among subframes of the downlink signal including the synchronization signal of the other base station, and
• wherein the base station comprises:
• a downlink signal receiving section of receiving a downlink signal including a synchronization signal transmitted from the other base station;
• an interference removing section of directly receiving a residual transmitting signal corresponding to a transmitter noise transmitted from the radio communication section by a wired communication link even in a timing of stopping the downlink signal transmission of the own base station, acquiring a complex baseband signal by converting from the received residual transmitting signal, generating a replica signal of the residual transmitting signal with respect to the predetermined subframe based on the acquired complex baseband signal, and removing an interference of the residual transmitting signal from the received signal of the downlink signal;
• and
• a synchronization processing section of performing a time synchronization processing with the other base station by detecting a synchronization signal timing of the other base station based on the received signal of the downlink signal from which the interference of the residual transmitting signal is removed.

A time synchronization method between base stations, the time synchronization method synchronizing between a first base station capable of performing a downlink signal transmission of an OFDM (Orthogonal Frequency Division Multiplexing) system to a mobile station and a second base station capable of performing a downlink signal transmission the OFDM system to a mobile station, an own cell of the second base station being located in a cell of the first base station,

• wherein the second base station:
• receives a downlink signal including a downlink signal including a synchronization signal transmitted from the first base station and a downlink wraparound signal transmitted from the own base station;
• removes an interference of the wraparound signal from a received signal of the downlink signal with respect to a predetermined subframe in which the downlink wraparound signal from the own base station interferes with the synchronization signal of the first base station, among subframes of the downlink signal including the synchronization signal of the first base station;
• and
• performs a time synchronization processing with the first base station by detecting a synchronization signal timing of the first base station based on a received signal of the downlink signal from which the interference of the wraparound signal is removed.

A time synchronization method between base stations, the time synchronization method synchronizing between a first base station capable of performing a downlink signal transmission of an OFDM (Orthogonal Frequency Division Multiplexing) system to a mobile station and a second base station capable of performing a downlink signal transmission of the OFDM system to a mobile station, an own cell of the second base station being located in a cell of the first base station,

• wherein the second base station:
• controls to stop a downlink signal transmission with respect to a predetermined subframe in which a downlink wraparound signal from an own base station interferes with a synchronization signal of the first base station, among subframes of the downlink signal including the synchronization signal of the first base station;
• directly receives a residual transmitting signal corresponding to a transmitter noise transmitted from a radio communication section of the own base station by a wired communication link even in a timing of stopping the downlink signal transmission of the own base station;
• acquires a complex baseband signal by converting from the received residual transmitting signal;
• receives a downlink signal including a synchronization signal transmitted from the first base station;
• generates a replica signal of the residual transmitting signal with respect to the predetermined subframe based on the acquired complex baseband signal;
• removes an interference of the residual transmitting signal from a received signal of the downlink signal;
• and
• performs a time synchronization processing with the first base station by detecting a synchronization signal timing of the first base station based on a received downlink signal from which the interference of the transmitter noise is removed.