A network device for modulating a plurality of network subscriber signals associated with different network subscribers, in accordance with the OFDM, Orthogonal Frequency Division Multiplexing, modulation scheme, comprising the following features: an allocation device for allocating a first group of subcarriers to a first network subscriber signal and for allocating a second group of subcarriers to a second network subscriber signal; or for allocating the first group of subcarriers to the first network subscriber signal and to a first portion of the second network subscriber signal and for allocating the second group of subcarriers to a second portion of the second network subscriber signal; a modulation device for modulating the first network subscriber signal onto the first group of subcarriers using inverse Fourier transform to obtain a first multi-carrier signal, and for modulating the second network subscriber signal onto the second group of subcarriers using inverse Fourier transform to obtain a second multi-carrier signal; or for modulating the first network subscriber signal and the first portion of the second network subscriber signal onto the first group of subcarriers using inverse Fourier transform to obtain a first multi-carrier signal, and for modulating the second portion of the second network subscriber signal onto the second group of subcarriers using inverse Fourier transform to obtain a second multi-carrier signal; wherein the allocation device is adapted to allocate a number of sub-carriers allocated to the first network subscriber signal to the second network subscriber signal if an increased number of subcarriers is necessary to modulate the second network subscriber signal and/or if a reduced number of subcarriers is sufficient to modulate the first network subscriber signal; and wherein the network device is adapted to modulate the plurality of network subscriber signals (101, 103) according to the OBM OFDM, Orthogonal Band Multiplexed OFDM, scheme, and wherein the network device is further adapted to transmit a control signal indicating the allocation of the first group of subcarriers to the first network subscriber signal and/or the allocation of the second group of subcarriers to the second network subscriber signal; an optical transmitter device (109, 111) for generating an optical signal from the first multi-carrier signal and/or the second multi-carrier signal, wherein the optical transmitter device (109, 111) comprises a first optical converter for converting the first multi-carrier signal into a first optical multi-carrier signal at a first carrier frequency, and a second optical converter for converting the second multi-carrier signal into a second optical multi-carrier signal at a second carrier frequency. an allocation device for allocating a first group of subcarriers to a first network subscriber signal and for allocating a second group of subcarriers to a second network subscriber signal; or for allocating the first group of subcarriers to the first network subscriber signal and to a first portion of the second network subscriber signal and for allocating the second group of subcarriers to a second portion of the second network subscriber signal; a modulation device for modulating the first network subscriber signal onto the first group of subcarriers using inverse Fourier transform to obtain a first multi-carrier signal, and for modulating the second network subscriber signal onto the second group of subcarriers using inverse Fourier transform to obtain a second multi-carrier signal; or for modulating the first network subscriber signal and the first portion of the second network subscriber signal onto the first group of subcarriers using inverse Fourier transform to obtain a first multi-carrier signal, and for modulating the second portion of the second network subscriber signal onto the second group of subcarriers using inverse Fourier transform to obtain a second multi-carrier signal; wherein the allocation device is adapted to allocate a number of sub-carriers allocated to the first network subscriber signal to the second network subscriber signal if an increased number of subcarriers is necessary to modulate the second network subscriber signal and/or if a reduced number of subcarriers is sufficient to modulate the first network subscriber signal; and wherein the network device is adapted to modulate the plurality of network subscriber signals (101, 103) according to the OBM OFDM, Orthogonal Band Multiplexed OFDM, scheme, and wherein the network device is further adapted to transmit a control signal indicating the allocation of the first group of subcarriers to the first network subscriber signal and/or the allocation of the second group of subcarriers to the second network subscriber signal; an optical transmitter device (109, 111) for generating an optical signal from the first multi-carrier signal and/or the second multi-carrier signal, wherein the optical transmitter device (109, 111) comprises a first optical converter for converting the first multi-carrier signal into a first optical multi-carrier signal at a first carrier frequency, and a second optical converter for converting the second multi-carrier signal into a second optical multi-carrier signal at a second carrier frequency.