Patent ID: 8649682

Claim:
A distribution node for a passive optical network comprising: a first port for receiving a first optical continuous envelope modulated downstream data signal at a first wavelength from a first optical line termination (OLT) unit; a second port for receiving a second optical continuous envelope modulated downstream data signal at a second wavelength from a second OLT unit; a third port for connecting to a first group of optical network units (ONUs); a fourth port for connecting to a second group of ONUs; a first converter which is arranged to perform continuous envelope modulation-to-intensity modulation conversion of the first optical downstream data signal and to forward the converted first optical downstream data signal to the first group of ONUs; and a second converter which is arranged to perform continuous envelope modulation-to-intensity modulation conversion of the second optical downstream data signal and to forward the converted second optical downstream data signal to the second group of ONUs; wherein the distribution node is further arranged to forward a seed signal at the first wavelength to the second group of ONUs and forward a seed signal at the second wavelength to the first group of ONUs, each seed signal being for use in forming an upstream modulated signal at an ONU.