Optical WDM (wavelength division multiplexing) transmission system and method for configuring the same

A method for configuring an optical WDM (Wavelength Division Multiplexing) transmission system by integrating a first point-to-multipoint optical transmission system and a second point-to-multipoint optical transmission system into a point-to-multipoint optical transmission system, said first point-to-multipoint optical transmission system splitting a first optical signal with a wavelength of .lambda..sub.1 output from a first center terminal, and supplying split optical signals to a plurality of first user terminals within a first allowed loss, and said second point-to-multipoint optical transmission system splitting a second optical signal with a wavelength of .lambda..sub.2 output from a second center terminal, and supplying split optical signals to a plurality of second user terminals within a second allowed loss, said method comprising the steps of:

• selecting a multi-service user terminal which receives both said first optical signal and said second optical signal from said first user terminals and said second user terminals;
• establishing a transmission line for supplying said multi-service user terminal with an optical signal formed by splitting a third optical signal obtained by optically combining said first optical signal and said second optical signal;
• and
• setting a splitting number of at least one of said first optical signal and said second optical signal such that an optical loss from said first center terminal to said first user terminal falls within said first allowed loss, and an optical loss from said second center terminal to said second user terminal falls within said second allowed loss.