Patent ID: 7266300

Claim:
A bi-directional path switched ring (BPSR) optical transmission node connected to a first optical line through which an odd channel signal and an even channel signal are respectively transmitted to and from the BPSR optical transmission node in directions opposite to each other, the BPSR optical transmission node being further connected to a second optical line through which the odd channel signal and the even channel signal are respectively transmitted from and to the BPSR optical transmission node in directions opposite to each other, the BPSR optical transmission node comprising: a node section for directing the odd channel signal and the even channel signal in an equal direction, for amplifying the odd channel signal and the even channel signal, for at least one of dropping a desired channel from and adding a desired channel to at least one of the odd channel signal and the even channel signal, and for then allowing each of the odd channel signal and the even channel signal to proceed in a direction traveled by that channel signal upon arriving at the BPSR optical transmission node; a first filtering means coupled between the first optical line and the node section, the first filtering means allowing only the odd channel signal from among signals transmitted through the first optical line to pass through the first filtering section without substantially any attenuation by said first filtering means, the first filtering means transferring the even channel signal from the node section to the first optical line; and a second filtering means coupled between the second optical line and the node section, the second filtering means allowing only the even channel signal from among signals transmitted through the second optical line to pass through the second filtering section without substantially any attenuation by said second filtering means, the second filtering means transferring the odd; wherein the node section comprises: an amplifier for amplifying the odd channel signal and the even channel signal; an optical add/drop multiplexer for at least one of adding a desired channel to and dropping a desired channel from at least one of the odd channel signal and the even channel signal after said amplifying of the at least one channel signal; and an interleaver for routing the odd channel signal and the even channel signal, which have passed through the first and second filtering means, respectively, to the amplifier, and for routing the odd channel signal having passed through the optical add/drop multiplexer to the second filtering means and the even channel signal having passed through the optical add/drop multiplexer to the first filtering means.