Frame synchronization system between base stations of mobile radio communication system and base station device employing this system

An inter-base-station frame synchronous system in a mobile communication system comprising:

• plural base stations dispersively arranged within a service area and connected to a communication network, and having at least one master base station and plural slave base stations;
• and
• plural mobile stations wirelessly connected to said plural base stations by a time-division bi-directional multiplex system, wherein
• said master base station comprises:
• time information receiving means for receiving time information with high precision externally supplied;
• reference frame timing generating means for generating reference frame timing for a time-divisional multiplex connection at a predetermined time based on said time information;
• and
• first control channel signal transmitting means for transmitting a control channel signal to said plural slave base stations located around said master base station in synchronization with said reference frame timing, wherein
• said slave base stations comprise:
• control channel signal observation period setting means in which a predetermined time period is set as a control channel signal observation period starting from a first receiving time point of a control channel signal transmitted from said master base station or other slave base stations during a frame synchronization control period;
• slave base station frame timing generating means for generating slave base station frame timing on the basis of receiving timing of the control channel signal transmitted from said master base station or one of the other slave base stations when only this control channel signal is received during said control channel signal observation period, said slave base station frame timing generating means also generating said slave base station frame timing on the basis of one of receiving timings of control channel signals respectively transmitted from said master base station or plural slave base stations among the other slave base stations when these control channel signals are received during said control channel signal observation period;
• and
• second control channel signal transmitting means for transmitting each control channel signal in synchronization with said slave base station frame timing after said control channel signal observation period is terminated, wherein
• said slave base station frame timing generating means generates said slave base station frame timing based on receiving timing at a maximum receiving level among the control channel signals respectively transmitted from the master base station or plural slave base stations among the other slave base stations when these control channel signals are received during the control channel signal observation period.

A method of synchronizing a plurality of base stations in an inter-base-station frame synchronous system of a mobile communication system, the method comprising the steps of:

• generating, by a master base station, reference frame timing for a time-division multiplex connection in synchronization with predetermined synchronous setting timing set based on externally supplied time information;
• transmitting, by the master base station, a control channel signal to a plurality of slave base stations located within a geographic zone around the master base station;
• receiving, by a slave base station within the geographic zone during a frame synchronization control period, timing of the control channel signal transmitted by the master base station and setting a control channel observation period starting from a first receiving time point of the control channel signal;
• generating, by the slave base station, reference frame timing based on the timing of the received control channel signal received during the channel observation period;
• transmitting, by the slave base station after termination of the control channel observation period, a second control channel signal in synchronization with the reference frame timing of the slave base station, the second control channel signal being transmitted to a plurality of slave base stations in a second geographic zone around the base station.

A method of synchronizing a plurality of base stations in an inter-base-station frame synchronous system of a mobile communication system, the method comprising the steps of:

• generating, by a master base station, reference frame timing for a time-division multiplex connection in synchronization with predetermined synchronous setting timing set based on externally supplied time information;
• transmitting, by the master base station, a control channel signal to a plurality of slave base stations located within a geographic zone around the master base station;
• receiving, by a slave base station within the geographic zone during a frame synchronization control period, timing of the control channel signal transmitted by one of the master base station and another slave base station and setting a control channel observation period starting from a first receiving time point of one of the control channel signal;
• generating, by the slave base station, reference frame timing based on the timing of the received control channel signal received during the channel observation period;
• and
• transmitting, by the slave base station after termination of the control channel observation period, a control channel signal in synchronization with the reference frame timing of the slave base station, the control channel signal from the slave base station being transmitted to a plurality of slave base stations in a second geographic zone around the slave base station.

A master base station of an inter-base-station frame synchronous system in a mobile communication system, comprising:

• time information receiving means for receiving time information with high precision externally supplied;
• reference frame timing generating means for generating reference frame timing for a time division multiplex connection in synchronization with predetermined synchronous setting timing set based on said time information;
• and
• first control channel signal transmitting means for transmitting a control channel signal to a plurality of slave base stations located in a first geographic zone around said master base station in synchronization with said reference frame timing.

A slave base station of an inter-base-station frame synchronous system in a mobile communication system, comprising:

• control channel signal observation period setting means in which a predetermined period from a first receiving time point of a control channel signal transmitted from another base station during a frame synchronization control period is set to a control channel signal observation period;
• frame timing generating means for generating frame timing on the basis of receiving timing of the received control channel signal when said control channel signal is received during said control channel signal observation period set by said control channel signal observation period setting means, said frame timing generating means also generating said frame timing based on one of receiving timings of control channel signals respectively transmitted by one or more other base stations when the control channel signals are received during said control channel signal observation period;
• and
• control channel signal transmitting means for transmitting each control channel signal to other base stations within a geographic zone around said slave base station in synchronization with said frame timing after said control channel signal observation period is terminated, wherein
• said frame timing generating means generates said station frame timing in synchronization with a frame timing of a most advanced phase among a plurality of frame timings based on respective receiving timings of the control channel signals respectively transmitted from the one or more other base stations when these control channel signals are received during the control channel signal observation period.

A slave base station of an inter-base-station frame synchronous system in a mobile communication system, comprising:

• control channel signal observation period setting means in which a predetermined period from a first receiving time point of a control channel signal transmitted from another base station during a frame synchronization control period is set to a control channel signal observation period;
• frame timing generating means for generating frame timing on the basis of receiving timing of the received control channel signal when said control channel signal is received during said control channel signal observation period set by said control channel signal observation period setting means, said frame timing generating means also generating said frame timing based on one of receiving timings of control channel signals respectively transmitted by one or more other base stations when the control channel signals are received during said control channel signal observation period;
• and
• control channel signal transmitting means for transmitting each control channel signal to other base stations within a geographic zone around said slave base station in synchronization with said frame timing after said control channel signal observation period is terminated, wherein
• said frame timing generating means generates said frame timing based on receiving timing at a maximum receiving level among the control channel signals respectively transmitted from the one or more other base stations when the control channel signals are received during the control channel signal observation period.