| US 7,389,048 B2 | ||
| Optical wavelength-division multiple access system and optical network unit | ||
| Jun-ichi Kani, Narashino (Japan); and Katsumi Iwatsuki, Yokohama (Japan) | ||
| Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (Japan) | ||
| Appl. No. 10/525,407 PCT Filed Jun. 18, 2004, PCT No. PCT/JP2004/008952 § 371(c)(1), (2), (4) Date Feb. 23, 2005, PCT Pub. No. WO2004/114555, PCT Pub. Date Dec. 29, 2004. |
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| Claims priority of application No. 2003-173898 (JP), filed on Jun. 18, 2003. | ||
| Prior Publication US 2006/0146855 A1, Jul. 06, 2006 | ||
| Int. Cl. H04J 14/00 (2006.01) | ||
| U.S. Cl. 398—72 [398/66; 398/67; 398/68; 398/69; 398/70; 398/71; 398/79; 398/99; 398/100; 398/91; 398/59; 398/140; 398/141; 398/135; 398/82; 398/84; 398/87; 398/89; 385/24; 385/37] | 9 Claims |
| 1. A wavelength-division multiple access system having a center apparatus (OLT), n optical network units (ONU), and m ONUs
arranged via a wavelength multi/demultiplex apparatus, the OLT and the wavelength multi/demultiplex apparatus being connected
together in a multiplex section via multiplex section optical fibers, the wavelength multi/demultiplex apparatus and the ONUs
being connected together in an access section via access section optical fibers, downlink optical signals from the OLT to
the ONUs and uplink optical signals from the ONUs to the OLT being transmitted through the multiplex section using wavelengths
assigned to the respective ONUs while multiplexing the wavelengths, the wavelength multi/demultiplex apparatus carrying out
wavelength multiplexing or demultiplexing for bidirectional transmissions,
wherein a wavelength band Da (wavelengths λd1 to λdn) for downlink optical signals corresponding to the n ONUs, a wavelength band Ua (wavelengths λu1 to λun) for uplink optical signals corresponding to the n ONUs, a wavelength band Db (wavelengths λdn+1 to λdn+m) for downlink
optical signals corresponding to the m ONUs, and a wavelength band Ub (wavelengths λun+1 to λun+m) for uplink optical signals
corresponding to the m ONUs are set different from one another, the wavelength bands Ua and Ub are set adjacent to each other,
and the wavelength bands Ua and Da or the wavelength bands Ub and Db are set adjacent to each other,
said OLT comprises:
means for multiplexing said downlink optical signals multiplexed in the wavelength band Da (wavelengths λd1 to λdn) and said downlink optical signals multiplexed in the wavelength band Db (wavelengths λdn+1 to λdn+m) and then transmitting
to the multiplex section optical fibers; and
means for demultiplexing the uplink optical signals transmitted via the multiplex section optical fibers into said uplink
optical signals multiplexed in the wavelength band Ua (wavelengths λu1 to λun) and said uplink optical signals multiplexed in the wavelength band Ub (wavelengths λun+1 to λun+m);
said wavelength multi/demultiplex apparatus comprises:
means for demultiplexing the downlink optical signals transmitted via the multiplex section optical fibers into said downlink
optical signals multiplexed in the wavelength band Da (wavelengths λd1 to λdn) and said downlink optical signals multiplexed in the wavelength band Db (wavelengths λdn+1 to λdn+m); and
means for multiplexing said unlink optical signals multiplexed in wavelength band Ua (wavelengths λu1 to λun) and said unlink optical signals multiplexed in wavelength band Ub (wavelengths λun+1 to λun+m) and then transmitting
to the multiplex section optical fibers; and
each of the ONUs comprises:
downlink optical signal receiving means for receiving a downlink optical signal of one of the wavelengths λd1 to λdn+m in the wavelength bands Da and Db which wavelength is assigned to the ONU; and
uplink optical signal transmitting means for transmitting an uplink optical signal of one of the wavelengths λu1 to λun+m in the wavelength bands Ua and Ub which wavelength is assigned to the ONU or an uplink optical signal within a broad
band including the wavelength bands Ua and Ub.
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