Communications system, communications method, transmitting apparatus, receiving apparatus and control program to variably adjust a symbol length

A communications method in which a first transmitting apparatus and a second transmitting apparatus share a frequency bandwidth, transmit respective information symbols by using the shared frequency bandwidth, and are initially configured to transmit the respective information symbols using different information symbol lengths with respect to the symbol length used by the other transmitting apparatus, the first transmitting apparatus being configured to communicate with a receiving apparatus in a first system using a first communication method and the second transmitting apparatus being configured to perform communication in a second system using a second communication method, the second system having a cell coverage area overlapping a cell coverage area of the first system, the method comprising:

• receiving, in the first transmitting apparatus, control information from the second system;
• identifying, in the first transmitting apparatus, a symbol length of a second information symbol transmitted from the second transmitting apparatus based on the received control information;
• and
• adjusting, in the first transmitting apparatus, a symbol length of a first information symbol transmitted from the first transmitting apparatus, by adding, to the first information symbol, a symbol length adjustment signal corresponding to the difference between the identified symbol length of the second information symbol and the symbol length of the first information symbol transmitted from the first transmitting apparatus.

A transmitting apparatus in a communications system in which the transmitting apparatus and a second transmitting apparatus share a frequency bandwidth, transmit respective information symbols by using the shared frequency bandwidth, and are initially configured to transmit the respective information symbols using different information symbol lengths with respect to the symbol length used by the other transmitting apparatus, the transmitting apparatus being configured to communicate with a receiving apparatus in a first system using a first communication method and the second transmitting apparatus being configured to perform communication in a second system using a second communication method, the second system having a cell coverage area overlapping a cell coverage area of the first system, the transmitting apparatus comprising:

• an identifying unit configured to receive control information from the second system and identify a symbol length of a second information symbol transmitted from the second transmitting apparatus based on the received control information;
• and
• an adjusting unit configured to adjust a symbol length of an information symbol to be transmitted from the transmitting apparatus, by adding, to the information symbol, a symbol length adjustment signal corresponding to the difference between the identified symbol length of the second information symbol received from the second transmitting apparatus and symbol length of the information symbol transmitted from the transmitting apparatus.

A receiving apparatus in a communications system which includes a first transmitting apparatus and a second transmitting apparatus, said first transmitting apparatus and second transmitting apparatus share a frequency bandwidth, transmit respective information symbols by using the shared frequency bandwidth, and are initially configured to transmit the respective information symbols using different information symbol lengths with respect to the symbol length used by the other transmitting apparatus, the first transmitting apparatus being configured to communicate with the receiving apparatus in the first system using a first communication method and the second transmitting apparatus being configured to perform communication in a second system using a second communication method, the second system having a cell coverage area overlapping a cell coverage area of the first system, the receiving apparatus comprising:

• an identifying unit configured to receive a reception signal from the second system and identify a symbol length of a second information symbol which is transmitted from the second transmitting apparatus based on the received reception signal;
• and
• an adjusting unit configured to specify a symbol length adjustment signal included in a received first information symbol received from the first transmitting apparatus and to remove the symbol length adjustment signal from the received first information symbol, in accordance with the identified symbol length of the second information symbol.

A computer readable recording medium having instruction code recorded thereon, the instruction code, when executed on a computer, is configured to provide a control program which controls a transmitting apparatus in a communications system in which the transmitting apparatus and a second transmitting apparatus share a frequency bandwidth, transmit respective information symbols by using the shared frequency bandwidth, and are initially configured to transmit the respective information symbols using different information symbol lengths with respect to the symbol length used by the other transmitting apparatus, the transmitting apparatus being configured to communicate with a receiving apparatus in a first system using a first communication method and the second transmitting apparatus being configured to perform communication in a second system using a second communication method, the second system having a cell coverage area overlapping a cell coverage area of the first system, wherein

• the control program makes the computer function as:
• an identifying unit configured to receive control information from the second system and identify a symbol length of a second information symbol which is the information symbol transmitted by the second transmitting apparatus based on the received control information;
• and
• a notifying unit configured to notify the transmitting apparatus of a symbol length adjustment signal to be added to a first information symbol transmitted by the transmitting apparatus, so as to adjust a symbol length of the first information symbol, by adding, to the first information symbol, a symbol length adjustment signal corresponding to the difference between the identified symbol length of the second information symbol and the symbol length of the first information symbol transmitted from the transmitting apparatus.