Communication system, control method and central station

A control method in a communication system including an aggregation station and an extension station that communicates with the aggregation station by an analog radio-over-fiber (RoF), wherein

• the control method by the aggregation station includes
• a delay measurement signal transmission step of transmitting a delay measurement signal to the extension station,
• a delay measurement signal reception step of receiving the delay measurement signal folded back by the extension station;
• and
• a delay measurement step of measuring a delay time from a timing at which the delay measurement signal is transmitted and a timing at which the delay measurement signal is received, and
• the control method by the extension station includes
• a delay measurement signal folding step of folding back the delay measurement signal to the aggregation station.

An aggregation station in a communication system including an aggregation station and an extension station that communicates with the aggregation station by an analog radio-over-fiber (RoF), the station comprising:

• a delay measurement signal transmission circuitry that transmits a delay measurement signal to the extension station;
• a delay measurement signal reception circuitry that receives the delay measurement signal folded back by the extension station;
• and
• a delay measurement circuitry that measures a delay time from a timing at which the delay measurement signal is transmitted and a timing at which the delay measurement signal is received.