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Optical access network system

a network system and optical access technology, applied in the field of optical access network systems, can solve the problems of increasing the number of subscribers, the inability to maintain physical secrecy, and the inability to achieve high-speed communication exceeding 100 mbps, so as to increase the number of subscribers and expand the bandwidth

Inactive Publication Date: 2009-07-23
FUJITSU LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical access network system that can expand bandwidth and increase the number of subscribers. It can be used in both long-distance transmission and tree-shaped or star-shaped network topology, making it widely used from access to a metro area. The system takes into consideration physical security, allowing enterprise users to feel at ease in using the system. It also lowers cost by increasing the number of users per system. The system includes a relay station that receives wavelength multiplexed optical signals and transmits them to subscriber units. The relay station has optical demultiplexing means, optical branching means, and optical switching means. The system also includes a subscriber unit with a wavelength selection filter and a decoding circuit for separating and decoding the optical signals. The system can perform bi-directional transmission over one fiber optic transmission path using one wavelength.

Problems solved by technology

In the case of a PON system, a network can be created using inexpensive passive optical elements, however, there is a problem in that it is possible to use only a bandwidth of approximately 30 to 100 Mbps per subscriber, and high-speed communication exceeding 100 Mbps is not possible.
Therefore, the danger of communication contents being decoded increases, making it impossible to maintain physical secrecy, and thus in a certain sense, the system can be said to be the same as a public wireless LAN.
As can be seen from the above explanation, a conventional PON system has the disadvantage in that there is insufficient security for financial or business uses.
However, since WDM optical signals are used, the number of users that can use a system is limited to a few tens of users due to restrictions of the number of multiplexed wavelengths, and to build a WDM-PON system, an enormous amount of fiber optic cables which connect between the communication carrier and users is necessary, which is reflected in the cost of the fiber optic equipment.
On the ONU side as well, when WDM optical signals are used, signal wavelength management of each individual ONU is necessary, which increases the cost of the ONU terminal.
In addition, in a WDM-PON, it is possible to maintain sufficient bandwidth, however, wasted bandwidth occurs due to ping-pong transmission.

Method used

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first embodiment

(B) First Embodiment

[0045]FIG. 4 is a drawing showing the overall construction of an optical communication network system that comprises the optical access network system of a first embodiment of the invention, where the transmission side SDS is connected to the optical access network system PACN via a broadband optical communication network BPN, and where in the optical access network system PACN, relay stations RST are connected to the user side by optical transmission paths.

[0046]The maximum distance between the transmission side SDS and a relay station RST is 300 km, the maximum distance between a first and second relay station RST1, 2 is 20 km, and the distance between a relay station RST and the user side USS is several km or less. The relay stations RST are divided into first and second relay stations RST1, RST2, and the optical access network PACN is built in a tree shape from the first relay station to a subscriber unit. The allowable number of users for one relay station R...

second embodiment

(C) Second Embodiment

[0090]FIG. 14 shows a second embodiment, where the same reference numbers are given to parts that are the same as those of the first embodiment shown in FIG. 4. The construction of this embodiment differs in that: (1) C-L couplers 20, 35 are provided on the transmission side and relay station side of a common transmission path 25; (2) the transmitter 65 of a subscriber unit performs intensity modulation of L-band signal light of a 1.5 μm band using transmission data, and transmits that signal light to the second relay station RST2-1; and (3) a serializer 50 is provided for each group in the second relay stations RST2-1 to RST2-8, and by shifting the optical signals that are input from each subscriber unit in time and combining them, outputs the signal as an optical signal having one wavelength. The C-L couplers 20, 35 are both optical wavelength multiplexing / demultiplexing filters, or optical circulators, and they select and transmit C-band optical signals in th...

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PUM

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Abstract

In an optical access network system in which a relay station receives a wavelength multiplexed and time-division multiplexed optical signal (WDM optical signal) from an optical network, and the relay station transmits optical signals having specified wavelengths to subscriber units, the relay station demultiplexes the WDM optical signal into a plurality of groups with one group having a plurality of optical signals having a fixed wavelength interval between signals, then divides the optical signals of each group into k branches (k is the number of subscriber units) and inputs the signals to optical switches, and by turning ON / OFF the optical switches such that they are spaced in time, inputs the branched optical signals to the respective specified subscribers units.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to an optical access network system that transmits high-speed optical signals to subscribers, and more particularly to an optical access network system that receives a multiplexed optical signal of a plurality of optical signals having different wavelengths from a broadband optical network, and transmits optical signals having specified wavelengths to subscribers.[0002]Various methods have been proposed as a next-generation optical access network system that transmits optical signals to a subscriber as is without performing electrical conversion. The work of global standardization is advancing, and as examples of such an access system, there is (1) E-PON (Ethernet PON Ethernet frames that is obtained by modifying a B-PON (Broadband Passive Optical Network) for ATM frames, (2) GE-PON (Giga Ethernet PON) for Giga Bit Ethernet, and (3) Unique-standard G-PON. These PON systems do not use active elements that perform electric...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04J14/00H04B10/27H04B10/07H04B10/272H04B10/297H04J14/02
CPCH04J14/0226H04J14/0227H04J14/0282H04J14/0232H04J14/0257H04J14/0246H04J14/0247H04J14/025H04J14/0252H04J14/0238
Inventor KAI, YUTAKAAOKI, YASUHIKO
Owner FUJITSU LTD