Fuente: Wipo "digitalization" A transmission/reception system includes: a second transmission/reception device configured to convert a multiplexed signal into a first digital signal in a first format, convert the signal into a first analog signal, and convert the signal into a second optical signal, and convert a first electrical signal into a second digital signal, demodulate the signal to generate a third digital signal, and output a plurality of sixth optical signals; and third transmission/reception device configured to convert a second electrical signal into a fourth digital signal, and demodulate the signal to generate a plurality of fifth digital signals; and convert a plurality of sixth digital signals into a seventh digital signal in a second format, convert the signal into a second analog signal, and convert the signal into a fourth optical signal.