Optical communication network node

Details Optical communication network node Optical communication network node

1998-07-30

2003-11-04

Yao, Kwang Bin (Department: 2662)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C359S107000, C370S395100, C370S396000, C370S535000

Reexamination Certificate

active

06643042

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an optical communication network node, and more particularly to an optical communication network node utilizing an asynchronous transfer mode (referred to as an ATM, hereinafter) technology and an optical wavelength dividing multiplex technology.
In recent years, together with improvement of a transmission band due to development of an optical fiber transmission technology, expectation to a broad band ISDN (referred to as a BISDN, hereinafter) has been raised, in which these kinds of communication services, such as voice, a data and an image, are contained together and which provides the services to a member. There is an ATM technology as a network technology indispensable for realizing this BISDN. The ATM is for dividing all information into packets, each having a fixed length, that are referred to cells, and transmitting the information after a header necessary for a routing is added thereto, as described in a publication “ATM-LAN” (authored by Hiroshi Shimizu and Hiroshi Suzuki, published by Soft Research Center on Feb. 10, 1995), for example.
In this case, the cells are transmitted to objective ATM nodes or terminals by means of two kinds of logical connections of a virtual circuit and a virtual path. The virtual circuit is the connection which is set by allocating network resources (a route and a band) necessary for communication between a plurality of terminals by means of a signaling procedure every time a call is generated.
The virtual path is a logical transmission path which is semifixedly preset between predetermined nodes in accordance with prediction of a demand for how many traffics are expected between nodes, such as exchanges and transmission devices within an ATM network, for example, or a monitoring result of an amount of traffics that are actually transmitted therebetween. The virtual path is a connection which does not depend on network topology formed by actually connecting transmission lines, such as optical fibers and coaxial cables, to each other. This virtual path contains a plurality of virtual circuits.
On the other hand, between ATM transmitting or exchange devices on the basis of such cells, because of development of an optical fiber communication technology, fast cells are converted into optical signals and transmitted. Moreover, in recent years, in order to make a network have a more massive capacity, an optical communication node is being investigated, in which a wavelength dividing multiplex typed optical cross-connect device for multiplexing and transmitting a plurality of optical wavelengths in one optical fiber transmission line and, in a communication node, an optical signal is switched to another predetermined node as it is, and an ATM device are combined.
Conventionally, as such an optical communication node, there is an optical communication network node described in First Optoelectronics and Communications Conference (OECC '96) Technical Digest, PD-1-5, pp. 10-11, 1996, “Optical Cross-connect System Using Fixed-wave Length Converters To Avoid Wavelength Blocking”, authored by Tatsuya, Shiragaki, Tomoki Kato, and Naoya Henmi.
FIG. 30
shows such an optical communication network node.
In addition, in explanation hereinafter, it is referred to a “drop” that a signal from a network constructed of the optical communication network node is sent to other networks and devices connected to a node of its own, as a matter of convenience. On the contrary, it is referred to an “insert” that a signal from other networks and devices connected to the node of its own is sent to the network constructed of the optical communication network node. Moreover, it is referred to a “pass” that a signal from an adjacent optical communication network node within the network is sent to other optical communication network nodes.
Optical signals from wavelength multi-inputting optical transmission lines
4100
-i (wherein i is 1 to M
1
, which is the same hereinafter.) are separated into optical signals having the n number of different wavelengths in wavelength de-multiplexers
4110
-i, and thereafter, are input to an optical switch network
4130
.
The optical switch network
4130
sends the optical signals from the wavelength de-multiplexers
4110
-i to predetermined wavelength converters
4140
-i·n or receiving interfaces
4160
-j (wherein j is 1 to M
2
, which is the same hereinafter.).
Each of the wavelength converters
4140
-(i·n-n+1) to
4140
-i·n fixedly converts a wavelength of the input optical signal into &lgr;1 to &lgr;n.
Wavelength multiplexers
4111
-i combines the optical signals from the wavelength converters
4140
-(i·n-n+1) to
4140
-i·n and sends the combined signals to wavelength multi-outputting optical transmission lines
4150
-i, respectively.
On the other hand, cells of the optical signals from the optical switch network
4130
are converted into cells of electric signals in receiving interfaces
4160
-k (wherein k is 1 to L, which is the same hereinafter.), respectively, and thereafter, are sent to an ATM switch
4170
. And, cells of the optical signals from input optical transmission lines
4180
-k are also converted into cells of electric signals in receiving interfaces
4161
-k, respectively, and thereafter, are sent to an ATM switch
4170
.
The ATM switch
4170
switches and outputs the input cells of the electric signals to predetermined transmitting interfaces
4162
-j or
4163
-k in accordance with headers thereof.
The switched cells of the electric signals are converted into cells of optical signals by the transmitting interfaces
4162
-j, and thereafter, are sent to the optical switch network
4130
.
The optical switch network
4130
also sends the cells of the optical signals from the transmitting interfaces
4162
-j to the predetermined wavelength converters
4140
-
1
to
4140
-M
1
·n or the receiving interfaces
4160
-J.
Also, the switched cells of the electric signals are converted into cells of optical signals by the transmitting interfaces
4163
-j, and thereafter, are sent to output optical transmission lines.
As described above, conventionally, the cells multiplied by the optical signals having an arbitrary wavelength, which are transmitted by the arbitrary wavelength multi-inputting optical transmission lines
4100
-i, can be dropped into the arbitrary output optical transmission lines
4190
-k. Also, the optical communication network node shown in
FIG. 30
converts the cells from the arbitrary input optical transmission lines
4180
-k into the optical signals having an arbitrary wavelength, and inserts the signals into the arbitrary wavelength multi-outputting optical transmission lines
4150
-i.
Moreover, the optical communication network node shown in
FIG. 30
can make the signals pass between the wavelength multi-inputting optical transmission lines
4100
-i and the wavelength multi-outputting optical transmission lines
4150
-i by converting the cells multiplied by the optical signals having an arbitrary wavelength, which are transmitted by the arbitrary wavelength multi-inputting optical transmission lines
4100
-i, into the optical signals having an arbitrary wavelength, and inserting the signals into the arbitrary wavelength multi-outputting optical transmission lines
4150
-i.
The above-mentioned conventional optical communication network node can conduct the drop and insert and further conduct the pass of the signals. However, this prior art has defects below.
First, in the above-mentioned prior art, two duplicate methods are used for conducting the conversion of a wavelength and passing the arbitrary optical signals between the wavelength multi-inputting optical transmission lines
4100
-i and the wavelength multi-outputting optical transmission lines
4150
-i. In other words, a method for realizing it by the optical switch network
4130
and the wavelength converters
4140
-
1
to
4140
-M
1
·n, and a method for realizing it by converting the optical signals from the optical switch network
4130
into the electric signals, and thereafte

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