Radio communications system

A radio communications system comprising:

• a first radio base station to convert multimedia broadcast multicast service (MBMS) data to unicast data and transmit the unicast data to an intermediate station;
• the intermediate station to receive the unicast data from the first radio base station and convert the unicast data to the MBMS data and broadcast the converted MBMS data to a mobile station;
• a second radio base station;
• and
• the mobile station to receive the same MBMS data from the first radio base station via the intermediate station and the second radio base station in the same period;
• wherein the first radio base station classifies subordinate stations into groups, and
• wherein the second radio base station comprises a transmitter that broadcasts, to one of the groups that is to receive the MBMS data from the intermediate station, the MBMS data that is the same as the MBMS data converted in advance by the intermediate station, at the same time when the intermediate station broadcasting the converted MBMS data to the mobile station by using same radio resource that the intermediate station uses in the broadcasting of the converted MBMS data.

A radio communications system comprising:

• a first radio base station;
• an intermediate station to receive data from the first radio base station and relay data to a mobile station;
• a second radio base station;
• and
• the mobile station to receive the same data from the first base station via the intermediate station and the second radio base station in the same period;
• wherein:
• the first radio base station converts unicast data to multimedia broadcast multicast service (MBMS) data and transmit the MBMS data;
• the intermediate station receives the MBMS data, converts the received MBMS data from the MBMS format to a unicast format, and relays the received data in the unicast format;
• and
• the second radio base station comprises a transmitter that transmits, using the unicast format, the data that is the same as the data converted in advance by the intermediate station, at the same time when the intermediate station transmitting the converted unicast data to the mobile station by using the same radio resource that the intermediate station uses in the transmission of the converted unicast data.

A radio communication method comprising:

• converting, by a first radio station, unicast data to multimedia broadcast multicast service (MBMS) data and transmitting the MBMS data to an intermediate station;
• receiving, by the intermediate station, the MBMS data;
• converting, by the intermediate station, covering a dead spot of the first radio base station the received data from the MBMS format to a unicast format, and transmitting the received data in the unicast format;
• transmitting, by a second radio base station, data that is the same as the data converted in advance by the intermediate station, at the same time when the intermediate station transmitting the converted unicast data to the mobile station by using the same unicast format;
• and
• receiving, by a mobile station, the same data from the first base station via the intermediate station and the second radio base station in the same period.

A radio communications system comprising:

• a first radio base station to convert multimedia broadcast multicast service (MBMS) data to unicast data and transmit the unicast data to an intermediate station;
• the intermediate station to receive the unicast data from the first radio base station and convert the unicast data to the MBMS data and broadcast the converted MBMS data;
• and
• a second radio base station;
• wherein:
• the first radio base station classifies stations into first and second groups, the first group being formed from the intermediate station and mobile stations that are to receive the unicast data directly from the first radio base station, the second group being formed from mobile stations that are to receive the converted MBMS data via the intermediate station;
• the first radio base station transmits the unicast data to the first group;
• the intermediate station receives the unicast data, executes converting operations on the received unicast data, and broadcasts the converted MBMS data to the second group;
• the second radio base station comprises a transmitter that broadcasts the MBMS data that is the same as the MBMS data converted in advance by the intermediate station, at the same time when the intermediate station broadcasting the converted MBMS data to the mobile station by using same radio resource that the intermediate station uses in the broadcasting of the converted MBMS data;
• and
• the mobile stations in the second group receive the same MBMS data from the first base station via the intermediate station and the second radio base station in the same period.

A radio communication method comprising:

• deploying a base station that transmits a radio signal having a multimedia broadcast multicast service (MBMS) format;
• deploying an intermediate station including a monitoring unit that monitors a number of mobile stations which receive the radio signal in the MBMS format under control of the intermediate station, and a communication format converter that performs conversion of the MBMS format before relaying the radio signal, depending on a result of the monitoring;
• and
• performing, by the communication format converter, conversion from the MBMS format to a unicast format so that the radio signal is relayed in the unicast format when the monitoring unit determines that the number of mobile stations falls below a threshold;
• wherein the MBMS format includes a first cyclic prefix and the unicast format includes a second cyclic prefix different from length of the first cyclic prefix of the MBMS format.