KR100641719B1 - Encoder and decoder for optical code division multiple access network - Google Patents

Abstract

The present invention relates to an encryptor and an decryptor for an optical code division multiple access network for generating an orthogonal optical code. In the related art, in order to configure an up-down transmission system using optical code division multiple access, another pair of encryptors and decoders must be configured, so the number of elements required for this is doubled. Therefore, there is a problem that the manufacturing cost of the system rises and the volume of the system increases. In the present invention, it uses a single waveguide array lattice router to transmit and receive and configures an encryptor and a decryptor. Therefore, since the length of the optical fiber is cut in half and the number of expensive waveguide array lattice routers can be reduced to half, the optical code division multiple access network can be configured, thereby significantly reducing the network construction cost.

Description

ENCODER AND DECODER FOR OPTICAL CODE DIVISION MULTIPLE ACCESS NETWORK}

1A is a block diagram showing an embodiment of an encryption apparatus for an optical code division multiple access network according to the prior art;

1B is a block diagram showing an embodiment of a decoder for an optical code division multiple access network according to the prior art;

FIG. 2 is a block diagram of a downlink transmission network configured using the encryptor and the decryptor illustrated in FIGS. 1A and 1B, respectively.

3 is a block diagram showing an embodiment of an encoder and a decoder for an optical code division multiple access network according to the present invention;

4 is a block diagram showing another embodiment of an encryptor and decrypter for an optical code division multiple access network according to the present invention;

FIG. 5 is a block diagram illustrating an uplink and downlink transmission network configured using an encoder and a decoder for the optical code division multiple access network shown in FIG. 4;

6 is a table illustrating one embodiment of a two-dimensional codeword.

<Description of the symbols for the main parts of the drawings>

62: encryptor

64, 84, 102, 112, 122, 140, 150: light source

66, 86, 100, 114, 124, 138, 148: notch filter

Waveguide Array Lattice Routers: 68, 72, 92, 96, 120, 130, 134, 144

88, 98, 116, 126, 136, 146: optical circulator

90, 104, 118, 128, 142, 152: photo detector

132: constellation combiner

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to encoders and decoders for optical code division multiple access networks, and more particularly to network encoders and decoders for generating orthogonal optical codes.

The basic concept of optical code division multiple access is similar to the code division multiple access used in wireless communication. Since one code is assigned to each subscriber and orthogonal characteristics between codes, subscribers using different codes cannot access the network at the same time. Unlike an electrical signal, an optical signal cannot take a negative value, and thus, there are many difficulties in transferring information using bipolar codes (1, 0, -1). Therefore, most optical codes use unipolar codes that carry "1" and "0".

In order to construct an optical code division multiple access network, systems using various types of coders and decoders have been proposed. Among them, a multi-wavelength optical code division multiple access technique is a feasible technique. This method uses the light emitted from the light emitting diode (LED), a noncoherent source, as a light source, and uses an optical fiber grating and an optical fiber delay line to construct an encryptor and a decoder. Only unidirectional transmission has been considered. Alternatively, a pair of wavelength / time domain optical code coders and decoders consisting of waveguide array grating multiplexers, optical fiber delay lines, and reflectors can be constructed.

FIG. 1A is a block diagram showing an embodiment of an encoder for an optical code division multiple access network according to the prior art, wherein a light source 2, an optical circulator 4, and an arrayed waveguide grating multiplexer (AWGM) ( 6), optical fiber delay lines 8 to 12, and reflectors RF11 to RF14.

1B is a block diagram showing an embodiment of a decoder for an optical code division multiple access network according to the prior art, including an optical circulator 22, a waveguide array lattice multiplexer 20, optical fiber delay lines 14-18, and It is comprised from reflecting mirrors RF21-RF25.

1A and 1B, the light source 2 emits broadband light emitted from a multi-wavelength light source or a light emitting diode, for example, and provides it to the input terminal In1 of the light circulator 4. The light circulator 4 provides the light received from the light source 2 to the waveguide array grating multiplexer 6.

The waveguide array grating multiplexer 6 separates optical pulses of various wavelength components corresponding to the light provided from the optical circulator 4 into different ports and passes through different optical fiber delay lines 8 to 12, respectively. And reflected by the reflectors RF11 to RF14, respectively. The reflected light pulses of various wavelength components are passed through the optical fiber delay lines 8 to 12 and the waveguide array grating multiplexer 6 to go through the optical circulator 4 to the output terminal Out1 at different times. The first optical pulse input as described above is encoded by the optical pulse train distributed in the wavelength / time domain and provided to the input terminal In2 of the optical circulator 22.

The operation of the decryptor as shown in FIG. 1B is similar to that of FIG. 1A, and the optical circulator receives the pulses of the length of the optical fiber delay lines 14 to 18 connected to the respective ports of the waveguide array lattice multiplexer 20 at the same time. It should be adjusted to go to the output terminal (Out2) of (22).

When the encrypted optical pulse train is input to the waveguide array grating multiplexer through the optical circulator 22, if the sequence of the decoders is opposite to the encoder and the spacing between the ports (the length of the optical fiber delay line) is properly adjusted, the pulse train is unified. Collected, one large power pulse can be sent to the output of the waveguide array grating multiplexer on the decoder side.

On the other hand, if the sequence of the input port of the decoder and the length of the delay line are not suitable for the encrypted signal, several small pulses are output instead of one large pulse.

Thus, if a pulse above a certain threshold power is output at the output of the decryptor, it is possible to decrypt the encrypted signal by judging it to "1" or "0", and signals from other encryptors that are not suitable for a given decryptor act as noise only. Done.

FIG. 2 is a block diagram of an up-and-down transmission network configured by using the encryptor and the decryptor shown in FIGS. 1A and 1B, respectively, and includes a switch 24 and a terminal 40. The exchanger 24 includes an encryptor 26 and a decryptor 34. Terminal 40 has an encryptor 48 and a decryptor 42. Encoder 26 includes a plurality of reflectors, a plurality of optical fiber delay lines, an arrayed waveguide grating router (AWGR) 32, an optical circulator 30, and a light source 28. The encryptor 48 includes a plurality of reflectors, a plurality of optical fiber delay lines, a waveguide array grating router 50, an optical circulator 52, and a light source 54. The decoder 34 has an optical circulator 36, a waveguide array grating router 38, a plurality of optical fiber delay lines, and a plurality of reflectors. The decoder 42 includes an optical circulator 44, a waveguide array grating router 46, a plurality of optical fiber delay lines, and a plurality of reflectors.

In the figure, in order to transmit up and down in an optical code division multiple access network, a pair of encoders and decoders can be used to construct a system. For example, if the exchange 24 includes a pair of encryptors 26 and a decryptor 34 and the terminal 40 includes a pair of encryptors 48 and a decryptor 42, the exchange 24 and the terminal 40 ) Enables bidirectional communication with each other.

In order to configure the up-down transmission system using the optical code division multiple access, another pair of encryptors and decoders must be configured, and thus the number of elements required for this is doubled. Therefore, there is a problem that the manufacturing cost of the system rises and the volume of the system increases.

The present invention has been made to solve the drawbacks of the prior art, to provide an encoder and a decoder for an optical code division multiple access network to transmit and receive using a single waveguide array grid router and to configure an encryptor and a decryptor. The purpose is.

The present invention for achieving the above object is an optical code division multiple access network encryptor comprising: a light source for emitting light; A filter for passing light of a specific band among the light emitted from the light source to provide an optical pulse of various wavelength components; Demultiplexing the optical pulses of various wavelength components provided from the filter and coupling to a plurality of optical fiber delay lines each having a different length, and then multiplexing the coupled optical pulses through the respective optical fiber delay lines And a waveguide array grating router for encrypting, coupling, and coupling to a predetermined output optical fiber.

Hereinafter, the embodiment of the present invention will be described in detail with reference to the following drawings.

3 is a block diagram showing an embodiment of an encryptor and decryptor for an optical code division multiple access network according to the present invention, which is composed of an encryptor 62 and a decryptor 70. As shown in FIG. Encryptor 62 includes a light source 64, a notch filter 66, a plurality of optical fiber delay lines, and a waveguide array grating router 68. The decoder 70 includes a plurality of optical fiber delay lines and waveguide array grating routers 70.

In the figure, the encoder 62 and the decoder 70 are orthogonal and cyclical codes, for example, are constructed using a prime code which is one of unipolar codes. The prime code consists of several chips, where a chip is a time slot generated by subdividing T, the data transmission period, to represent one bit of information, where information "1" is optical. Send a pulse and the information "0" transmits nothing. As shown in FIG. 6, which illustrates an embodiment of a two-dimensional codeword, a signal encrypted by the encoder 62 using a prime code is a signal corresponding to a code assigned to each subscriber through correlation in the decoder 70. Only detoxification.

The two-dimensional multi-wavelength optical code can be represented by the matrix X. When X _{i, j, which} is a member of the matrix, 1, an optical pulse having a wavelength? I exists in the time chip.

The light source 64 emits light to the notch filter 66 using, for example, a light emitting diode that is a noncoherent source.

The notch filter 66 passes light of a specific band among the light emitted from the light source 64 to provide light pulses of various wavelength components to the waveguide array grating router 68.

The waveguide array grating router 68 demultiplexes the optical pulses of various wavelength components provided from the notch filter 66 and couples them into a plurality of optical fiber delay lines each having a different length, and then couples through each optical fiber delay line. The ringed optical pulses are multiplexed and coupled to a predetermined output optical fiber, and the optical pulses of various wavelength components are encoded into a plurality of small pulses of power pulses dispersed in a wavelength / time region and provided to the decoder 70. In this process, optical pulses of different wavelength channels passing through different lengths of optical fiber delay lines are dispersed in the time domain.

Here, assuming that the center wavelength of the waveguide array grating router 68 is λ 0, the wavelength channels have a cyclic characteristic. In order to obtain an encrypted optical pulse sequence of the same power, the wavelength λ 7 is removed by the notch filter 66, and the wavelength λ 7 passes through the waveguide array grating router 68 only once, and thus has less loss than other wavelengths. Get

The operation of the decoder 70 is similar to that of the encoder 62, and the pulses of the length of the optical fiber delay lines connected to the respective ports of the waveguide array grating router 72 are output to the output terminal of the decoder 70 at the same time. You have to adjust it. Codewords can be constructed by adjusting the length and position of the optical fiber delay line.

Such a decryptor 70 can be used as an encryptor, and the sequence encrypted by the decryptor 70 can only be decrypted by the encryptor 62. It can be seen that the sequence encrypted by the decryptor 70 is the same as the codeword C ₆ of FIG. 6. By using the bidirectional optical code division multiple access function of the waveguide array lattice routers 68 and 72, it is possible to configure a vertical transmission system using one optical fiber.

4 is a block diagram showing another embodiment of an encryptor and a decryptor for an optical code division multiple access network according to the present invention, and is composed of a switch 82 and a terminal 94. As shown in FIG. The exchanger 82 includes a light source 84, notch filter 86, light circulator 88, light detector 90, a plurality of optical fiber delay lines, and a waveguide array grating router 92. The terminal 94 includes a light source 102, a notch filter 100, an optical circulator 98, an optical detector 104, a plurality of optical fiber delay lines, and a waveguide array grating router 96.

In the figure, when transmitting signals through the optical fiber delay line from the switch 82 to the terminal 94, the light source 84 and the notch filter 86 are connected to the light source 64 and the notch filter 66 of FIG. Works together. That is, the light source 84 emits light to provide the notch filter 86, and the notch filter 86 passes light of a specific band among the light emitted from the light source 84 to output light pulses of various wavelength components. do.

The optical circulator 88 provides optical waveguides of various wavelength components provided from the notch filter 86 to the waveguide array grating router 92. The waveguide array grating router 92 operates like the waveguide array grating router 68 of FIG. 3 to demultiplex the optical pulses of various wavelength components provided from the optical circulator 88 and have a plurality of optical fibers each having a different length. After coupling to a delay line, the optical pulses coupled through each optical fiber delay line are multiplexed and coupled to a predetermined output optical fiber so that optical pulses of various wavelength components are dispersed in the wavelength / time domain. Encrypted by the optical pulse train and provided to the waveguide array grating router 96 in the terminal 94 through the optical fiber delay line.

The waveguide array grating router 96 operates like the waveguide array grating router 72 of FIG. 3, and adjusts the pulses in which the lengths of the optical fiber delay lines connected to the respective ports are distributed to the optical circulator 98 at the same time. do. The optical circulator 98 provides the optical detector 104 with optical pulses of various original wavelength components provided from the waveguide array grating router 96. The photo detector 104 generates an electrical signal corresponding to the light pulse provided from the light circulator 98.

On the contrary, when the signal is transmitted from the terminal 94 to the switch 82 through the optical fiber delay line, the terminal 82 transmits the signal from the switch 82 to the terminal 94 through the optical fiber delay line. Finally, the photo detector 90 generates an electrical signal corresponding to the light pulse provided from the light circulator 88.

FIG. 5 is a block diagram of an uplink and downlink network configured by using an encoder and a decoder for the optical code division multiple access network shown in FIG. 4, the light sources 112, 122, 140, 150, notch filters 114, 124, 138, 148, Optical circulators 116, 126, 136, 146, photo detectors 118, 128, 142, 152, waveguide array grating routers 120, 130, 134, 144, and constellation combiner 132.

In the figure, the operation of the light sources 112 and 122, the notch filters 114 and 124, the light circulators 116 and 126, the light detectors 118 and 128, and the waveguide array grating routers 120 and 130 are shown in FIG. In Fig. 4, the operation of the light source 84, the notch filter 86, the optical circulator 88, the photo detector 90, and the waveguide array grating router 92 is similar to that of the operation.

The operation of the light sources 140 and 150, the notch filters 138 and 148, the light circulators 136 and 146, the light detectors 142 and 152, and the waveguide array grating routers 134 and 144 are illustrated in FIG. 4. 102, the notch filter 100, the optical circulator 98, the optical detector 104, and the waveguide array grating router 96 are similar to those of the operation, and the description thereof is also omitted.

In FIG. 4, the waveguide array grating routers 92 and 96 are connected by optical fiber delay lines, and in FIG. 5, the waveguide array grating routers 120, 130, 134 and 144 are connected to the constellation combiner 132. The constellation coupler 132 is used to connect a plurality of waveguide array grating routers to each other.

As described above, the present invention allows the transmission and reception using one waveguide array lattice router and configures an encryptor and a decryptor. Therefore, since the length of the optical fiber is cut in half and the number of expensive waveguide array lattice routers can be reduced to half, the optical code division multiple access network can be configured, thereby significantly reducing network construction costs.

Claims (7)

For encoders for optical code division multiple access networks: A light source for emitting light; A filter for passing light of a specific band among the light emitted from the light source to provide an optical pulse of various wavelength components; Demultiplexing the optical pulses of various wavelength components provided from the filter and coupling them to a plurality of optical fiber delay lines each having a different length, and then multiplexing and encrypting the coupled optical pulses through the respective optical fiber delay lines An encoder for an optical code division multiple access network comprising a waveguide array grating router for coupling to a desired output fiber. The method of claim 1, And the light source emits light using a light emitting diode. For decoders for optical code division multiple access networks: The optical pulses of various wavelength components are dispersed in the wavelength / time domain, decoded into a plurality of optical pulse trains to demultiplex the provided optical signals, and coupled to a plurality of optical fiber delay lines each having a different length, and then each optical fiber delay And a waveguide array grating router for multiplexing the optical pulses coupled through the line to couple the optical pulses before they are encrypted to a predetermined output optical fiber. For encoders and decoders for optical code division multiple access networks: The encoder includes a light source for emitting light; A filter for passing light of a specific band among the light emitted from the light source to provide an optical pulse of various wavelength components; Demultiplexing the optical pulses of various wavelength components provided from the filter and coupling them to a plurality of optical fiber delay lines each having a different length, and then multiplexing and encrypting the coupled optical pulses through the respective optical fiber delay lines A first waveguide array grating router for coupling to a desired output optical fiber, The decoder demultiplexes the optical signal provided from the first waveguide array grating router into multiple optical fiber delay lines having different lengths, and then couples the optical signals through the respective optical fiber delay lines. And a second waveguide array grating router for multiplexing pulses to couple optical pulses before they are encrypted to a desired output optical fiber. For encoders for optical code division multiple access networks: A light source for emitting light; A filter for passing light of a specific band among the light emitted from the light source to provide an optical pulse of various wavelength components; An optical circulator for providing an optical pulse provided from the filter through an output stage and an optical pulse received through the output stage to a specific optical detection stage; An optical detector for generating an electrical signal corresponding to an optical pulse provided through an optical detection stage of the optical circulator; Demultiplexing the optical pulses of various wavelength components provided from the output end of the optical circulator and coupling them to a plurality of optical fiber delay lines each having a different length, and then multiplexing the coupled optical pulses through the respective optical fiber delay lines And encrypting and coupling to a predetermined output optical fiber, and for the encrypted optical pulse provided through the predetermined output optical fiber, the encryption process is reversed to provide a decrypted optical pulse to an output terminal of the optical circulator. Encryptor for optical code division multiple access networks, including grid routers. For decoders for optical code division multiple access networks: The optical pulses of various wavelength components are dispersed in the wavelength / time domain, decoded into a plurality of optical pulse trains to demultiplex the provided optical signals, and coupled to a plurality of optical fiber delay lines each having a different length, and then each optical fiber delay Multiplexing the coupled optical pulses over a line to couple the optical pulses before they are encrypted to a predetermined output optical fiber, and the decryption process for the pre-encrypted optical pulses provided through the predetermined output optical fiber. A waveguide array lattice router performing reverse to provide an encrypted optical pulse; An optical circulator for outputting the decoded optical pulses provided from the waveguide array grating router to a specific optical detection stage and providing the input optical pulses to the waveguide array grating router; A photo detector for generating an electrical signal corresponding to a light pulse provided from a specific light detection stage of the optical circulator; A light source for emitting light; And a filter for passing light of a specific band among the light emitted from the light source to input light pulses of various wavelength components to the optical circulator. For encoders and decoders for optical code division multiple access networks: The encoder includes a first light source for emitting light; A first filter passing light of a specific band among the light emitted from the first light source to provide an optical pulse of various wavelength components; A first optical circulator for providing an optical pulse provided from the first filter through an output stage and providing an optical pulse received through the output stage to a specific optical detection stage; A first photodetector for generating an electrical signal corresponding to an optical pulse provided through the photodetection stage of the first optical circulator; Demultiplexing the optical pulses of various wavelength components provided from the output end of the first optical circulator and coupling them into a plurality of optical fiber delay lines each having a different length, and then the coupled optical pulses through the respective optical fiber delay lines Multiplexed and encrypted and coupled to a predetermined output optical fiber, and for the encrypted optical pulse provided through the predetermined output optical fiber, the encryption process is reversed, and the decrypted optical pulse is output to the output terminal of the first optical circulator. Providing a first waveguide array grating router, The decoder demultiplexes the optical signal provided from the first waveguide array grating router into multiple optical fiber delay lines having different lengths, and then couples the optical signals through the respective optical fiber delay lines. The multiplexed pulses couple the optical pulses before they are encrypted to a predetermined output optical fiber, and the decryption process is reversed for the non-encrypted optical pulses provided through the predetermined output optical fiber, thereby encrypting the encrypted optical pulses. A second waveguide array grating router providing a to the first waveguide array grating router; A second optical circulator for outputting the decoded optical pulses provided from the second waveguide array grating router to a specific optical detection stage and providing the input optical pulses to the second waveguide array grating router; A second photo detector for generating an electrical signal corresponding to an optical pulse provided from a specific light detection stage of the second optical circulator; A second light source for emitting light; And a second filter for passing a light of a specific band among the light emitted from the second light source to input light pulses of various wavelength components to the second optical circulator.

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