| 摘要 |
PROBLEM TO BE SOLVED: To restrain adverse effects of ASE noise in a multi-rate Passive Optical Network (PON) system where home optical line terminating devices (ONUs) having a plurality of transmission rates are accommodated existing alongside each other, thereby increasing the maximum number of branches and the maximum transmission distance per fiber optic line.SOLUTION: A station side optical line terminating device (OLT) 100 comprises an optical amplifier 350 whose gain of optical signal amplification is variable and a wavelength filter 340 whose pass wavelength band is variable. According to the transmission rates and transmission wavelengths of each ONU 110, instructions to change the gain of the optical amplifier 350 and the pass wavelength band of the wavelength filter 340 are given. At this time, a grant generation unit 260 of the OLT 100 assigns a time slot for time division multiplex control to each ONU 110 collectively for each transmission rate and further for each transmission wavelength band, so that the number of times such changes are needed will be reduced. |
