Communication device, radio communication system, and synchronization signal transmission method

A communication device comprising:

• a plurality of antenna elements;
• a plurality of power amplifiers that are provided in association with the plurality of antenna elements;
• a plurality of phase shifters that are provided in association with the plurality of antenna elements;
• and
• a processor that controls the plurality of power amplifiers and the plurality of phase shifters, wherein the processor executes a process including:
• acquiring maximum number of beam information that indicates the maximum number of beams formed by the own device;
• determining a width and a direction of each of the beams such that a number of beams that covers a cell is equal to or less than the maximum number of beams;
• setting, to each of the phase shifters, an amount of phase shift for forming a beam having the determined width and the determined direction;
• and
• transmitting synchronization signals that are different for each of the beams formed by the respective phase shifters.

A radio communication system comprising:

• a plurality of radio units;
• and
• a communication control device that is connected to the plurality of radio units, wherein
• the communication control device includes
• a communication interface that communicates with the plurality of radio units, and
• a processor that is connected to the communication interface, wherein the processor executes a process including:
• determining a maximum number of beams that indicates an upper limit of a number of beams formed by each of the plurality of radio units such that a sum total of the number of beams formed by the plurality of radio units is equal to or less than a number of synchronization signals that are able to be transmitted within a predetermined time unit;
• and
• notifying the plurality of radio units of the determined maximum number of beams.

A synchronization signal transmission method comprising:

• determining a maximum number of beams that indicates an upper limit of a number of beams formed by each of a plurality of radio units such that a sum total of the number of beams formed by the plurality of radio units is equal to or less than a number of synchronization signals that are able to be transmitted within a predetermined time unit, the plurality of radio units including a plurality of antenna elements and a plurality of phase shifters that are associated with the plurality of respective antenna elements;
• determining a width and a direction of each of the beams such that the number of beams that covers a cell associated with each of the plurality of radio units is equal to or less than the maximum number of beams;
• setting, to each of the phase shifters, an amount of phase shift for forming a beam having the determined width and the determined direction;
• and
• transmitting synchronization signals that are different for each of the beams formed by the respective phase shifters, using a processor.