A receiver arrangement for receiving an optical signal comprising a number of optical channels equally distributed around an optical carrier frequency. The arrangement is configured to: i) received and detect the multichannel optical signal so as to provide at least one electrical quadrature signal comprising at least one folded channel, wherein each folded channel correspond to a set of two optical channels collapsed onto each other; ii) up-convert said at least one electrical quadrature signal so as to provide at least one up-converted quadrature signal comprising at least one pair of two separated unfolded channels, wherein each pair correspond to the two optical channels of a unique folded channel; and iii) demodulating said at least one up-converted quadrature signal so as to provide one baseband quadrature signal for each un folded channel such that each baseband quadrature signal corresponds to one unique optical channel.