JP2008092488A - Optical frequency hopping code division multiplex transmission system and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network system by which information signals can be sent and received via an optical transmission path without using an expensive optical wavelength filter at the time of optical code division multiplex transmission. <P>SOLUTION: By the optical frequency hopping code division multiplex transmission system and the optical frequency hopping code division multiplex transmission method, coded light 56 which is coded by a temporal-optical frequency hopping spread code 54 for temporally varying the optical frequency is transmitted together with signal light 53 on the side of transmission of information signals 51. Light beat signals 61 generated by the coded light 56 and the signal light 53 are received. The light beat signals 61 are decoded by using a temporal-optical beat frequency spread code which is obtained by converting the optical frequency of frequency hopping into a frequency difference between the coded light and the signal light and the information signals 51 are demodulated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a system and method for optical multiple access transmission, and more particularly to optical CDM (code division multiplexing) transmission.

In the conventional optical CDM system, spread coding is performed on the time axis or on the optical wavelength or frequency axis. In spread coding on the time axis, high-speed signal processing is required in proportion to a wider band. On the other hand, in spreading coding on the optical wavelength or frequency axis, filtering processing for each optical wavelength is required for spreading and despreading. There is no example in which the optical CDM method is applied to wireless communication.
10Gb / s × 2ch Signal Unrepeated Transmission Over 100km of Data Rate Enhanced Time-Spread / Wavelength-Hopping OCDM USING 2.5-Gb / s-FBG END 15, NO. 2, FEBRUARY 2003

  As the signal speed increases and the number of nodes increases, a long code length is required. At this time, in spread coding on the time axis, required signal processing becomes faster. On the other hand, in the spread coding on the optical wavelength or frequency axis, the wavelength interval or frequency interval is narrowed, so that a highly accurate setting of the optical wavelength or frequency is required. As a result, the spread coding on the time axis, the optical wavelength, or the frequency axis has a problem that the design of the optical device becomes complicated and expensive.

  In particular, in spread coding on the optical wavelength or frequency axis, it is necessary to maintain the wavelengths of a plurality of light sources and wavelength filters with high accuracy at the absolute frequency level. However, the light source and the wavelength filter are easily affected by the external environment such as temperature. For this reason, it has been difficult to maintain the wavelength with high accuracy between remote nodes with completely different external environments. Furthermore, since it is necessary to maintain the wavelength of multiple light sources and wavelength filters with high accuracy at the absolute frequency level, it is not possible to dynamically change the design of the optical wavelength, and it is flexible to changes in the node configuration. It is difficult to respond.

  In addition, when a part of the transmission path section is wireless, a normal optical transmission scheme transmits and receives baseband signals. For this reason, in order to make a part of the section of the optical transmission line wireless, it is necessary to provide a wireless base station having a function of converting the signal light into an electric signal and further converting it into a baseband signal. There is a problem that becomes.

  An object of the present invention is to provide an optical code division multiplexing transmission system and an optical code division multiplexing transmission method capable of transmitting and receiving an information signal through an optical transmission line without using an expensive optical wavelength filter in optical code division multiplexing transmission. And

  The present invention transmits code light encoded by a temporal-optical frequency hopping spread code that temporally fluctuates the optical frequency on the information signal transmission side together with signal light, and light generated by the code light and signal light. Receives a beat signal, decodes the optical beat signal using a temporal-optical beat frequency spread code obtained by converting the optical frequency of frequency hopping into a frequency difference between the coded light and the signal light, and demodulates the information signal And

  Specifically, an optical frequency hopping code division multiplexing transmission system according to the present invention is an optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line and an information signal is transmitted and received between the nodes. The transmitting node among the nodes stores a temporal-optical frequency hopping spreading code storage unit that stores a temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other are allocated for each chip time, and Temporal-optical frequency hopping for outputting an optical frequency hopping signal for changing an optical frequency for each chip time according to the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage unit The temporal-optical frequency hopping is performed by a spread code modulator and the optical frequency hopping signal. A code light emitting unit that emits code light having an optical frequency changed to an optical frequency assigned by a spreading code, and a temporal-optical frequency hopping spread of a modulation signal that is modulated on or off according to the information signal. An information signal modulating unit that outputs each block of code, a signal light emitting unit that emits signal light having a constant optical frequency and that is modulated on or off by the modulation signal, and an output of the code light emitting unit A combined light emitting unit for combining the coded light and the signal light emitted from the signal light emitting unit, and emitting the combined light to the optical transmission path, An optical beat signal receiving unit for photoelectrically converting the combined light emitted from the combined light emitting unit into an electrical signal and receiving an optical beat signal of the combined light; and an optical frequency of the temporal-optical frequency hopping spread code The light for each chip time according to a temporal-optical beat frequency spread code replaced with an optical beat frequency that is a frequency difference between the optical frequency of the code light emitting section and the optical frequency of the temporal-optical frequency hopping spread code By extracting the beat frequency component from the optical beat signal received by the optical beat signal receiver, the temporal-temporal decoding of the optical beat signal of the signal light encoded by the temporal-optical frequency hopping spreading code is performed. -An optical frequency hopping spreading code decoding unit; and an information signal demodulating unit that demodulates the information signal from an optical beat signal of the signal light decoded by the temporal-optical frequency hopping spreading code decoding unit. To do.

  An optical frequency hopping code division multiplexing transmission system according to the present invention is an optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line, and transmits and receives information signals between the nodes. The transmitting node includes a temporal-optical frequency hopping spreading code storage unit for storing a temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other are allocated for each chip time, and the temporal An optical frequency hopping signal for changing an optical frequency in a predetermined time zone within the chip time according to the temporal optical frequency hopping spread code stored in the optical frequency hopping spread code storage unit; Output temporally-optical frequency hopping spread code modulation unit for each, and in the predetermined time zone, A code light having an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spreading code is emitted by a frequency hopping signal, and in a time zone excluding the predetermined time zone within the chip time, the optical frequency The code light emitting unit that emits constant signal light and the signal light emitted from the code light emitting unit are turned on or off for each block of the temporal-optical frequency hopping spread code according to the information signal. A signal light emitting unit that emits the modulated signal light and the coded light, a light branching unit that branches the signal light and the coded light emitted from the signal light emitting unit, respectively, and the light The time of the predetermined time zone is set so that the timing of emission of the code light and the timing of emission of the signal light coincide with each other of the signal light and the code light branched by the branching unit. An optical delay unit that delays by a time width that is less than the time width of the chip time, and the signal light and code light delayed by the optical delay unit and the other signal light and code that are branched by the optical branch unit. A combined light emitting unit for combining the signal light and the combined light, and outputting the combined light to the optical transmission path, wherein the node that receives the light is the combined light emitting An optical beat signal receiving unit that photoelectrically converts the combined light emitted by the unit into an electrical signal and receiving an optical beat signal of the combined light; and an optical frequency of the temporal-optical frequency hopping spread code of the signal light According to the temporal-optical beat frequency spread code replaced with the optical beat frequency that is the frequency difference between the optical frequency and the optical frequency of the temporal-optical frequency hopping spread code, the component of the optical beat frequency for each chip time is Temporal-optical frequency hopping diffusion for decoding the optical beat signal of the signal light encoded by the temporal-optical frequency hopping spread code by extracting from the optical beat signal received by the optical beat signal receiving unit A code decoding unit; and an information signal demodulating unit that demodulates the information signal from the optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding unit.

  An optical frequency hopping code division multiplexing transmission system according to the present invention is an optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line, and transmits and receives information signals between the nodes. The transmitting node includes a temporal-optical frequency hopping spreading code storage unit for storing a temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other are allocated for each chip time, and the temporal An optical frequency hopping signal for changing an optical frequency in a predetermined time zone within the chip time according to the temporal optical frequency hopping spread code stored in the optical frequency hopping spread code storage unit; Output temporally-optical frequency hopping spread code modulation unit for each, and in the predetermined time zone, A code light having an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spreading code is emitted by a frequency hopping signal, and in a time zone excluding the predetermined time zone within the chip time, the optical frequency The code light emitting unit that emits constant signal light and the signal light emitted from the code light emitting unit are turned on or off for each block of the temporal-optical frequency hopping spread code according to the information signal. A signal light emitting unit that emits the modulated signal light and the code light to the optical transmission path, and the node that receives the signal includes the signal light emitted from the signal light emitting unit and An optical branching unit that splits the code light into two, and the signal light and the code light that is branched from the optical branching unit are divided into the output timing of the code light and the signal light. An optical delay unit that delays by a time width that is greater than or equal to the time width of the predetermined time period and less than the time width of the chip time, and the signal light and the code that are delayed by the optical delay unit A combined light emitting unit for combining light and the other signal light branched by the light branching unit and the combined light, and emitting combined light obtained by combining the signal light and the combined light; and the combined light emitting unit The combined light emitted from the optical signal is photoelectrically converted into an electrical signal, and an optical beat signal receiving unit that receives the optical beat signal of the combined light; and the optical frequency of the temporal-optical frequency hopping spread code is set to the light of the signal light In accordance with the temporal-optical beat frequency spread code replaced with the optical beat frequency, which is the frequency difference between the frequency and the optical frequency of the temporal-optical frequency hopping spread code, the component of the optical beat frequency for each chip time is pre- Temporal-optical frequency hopping spread for decoding the optical beat signal of the signal light encoded by the temporal-optical frequency hopping spread code by extracting from the optical beat signal received by the optical beat signal receiving unit A code decoding unit; and an information signal demodulating unit that demodulates the information signal from the optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding unit.

  The optical frequency hopping code division multiplexing transmission system according to the present invention further comprises a plurality of radio base stations that are connected to the node through the optical transmission path and transmit / receive the information signal, and the radio base station transmitting the radio base station The station wirelessly transmits the optical beat signal received by the optical beat signal receiving unit and the optical beat signal receiving unit that photoelectrically converts the combined light emitted from the combined light output unit and receives the optical beat signal of the combined light. A radio signal transmitting unit for transmitting, the radio base station receiving among the radio base stations is a radio signal receiving unit for receiving an optical beat signal transmitted by radio from the radio signal transmitting unit, and the signal light emitting unit Code light having an optical frequency obtained by adding the frequency of the optical beat signal received by the wireless signal receiving unit to the optical frequency of the signal light emitted by the signal light, and the signal light emitted by the signal light emitting unit The signal light of frequency multiplexes, the base station emitting unit for emitting a multiplexed the multiplexed light to the optical transmission path is preferably provided with a. Since the combined light of the signal light and the code light is transmitted, if the optical frequency of the signal light and the code light is selected so that the optical beat signal is in the millimeter wave class, the wireless transmission is easily incorporated into a part of the optical transmission line. be able to. Thereby, flexibility can be given to the form of the network.

  In the optical frequency hopping code division multiplexing transmission system according to the present invention, the timing of the code light input to the combined light output unit and the timing of the signal light input to the combined light output unit are the temporal-light A timing adjustment unit for matching each block of the frequency hopping spread code is further provided in a preceding stage of the combined light output unit, and the combined light output unit is synchronized for each block of the temporal-optical frequency hopping spread code It is preferable to combine the code light and the signal light. By further including a timing adjustment unit, a timing shift at the time of multiplexing of the coded light and the signal light is prevented, and the light encoded with the temporal-optical frequency hopping spread code every time the information signal is turned on or off A beat signal can be generated.

  An optical frequency hopping code division multiplexing transmission method according to the present invention is an optical frequency hopping code division multiplexing transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes. At a transmitting node, a temporal-optical frequency hopping spread code storage unit stores a temporal-optical frequency hopping spread code in which optical frequencies orthogonal to each other are allocated for each chip time. A hopping spread code storing procedure and a light in which the temporal-optical frequency hopping spread code modulating unit varies the optical frequency according to the temporal-optical frequency hopping spread code storing procedure stored in the temporal-optical frequency hopping spread code storing procedure. Temporal-optical frequency hopping spread code for outputting frequency hopping signal every chip time A modulation procedure, and a code light emitting unit that emits code light having an optical frequency changed to the optical frequency assigned by the temporal-optical frequency hopping spread code by the optical frequency hopping signal, and information A signal modulation unit modulates the modulation signal to be turned on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, and the optical frequency hopping signal of the temporal-optical frequency hopping spread code modulation procedure. Information signal modulation procedure that is output in synchronization with the signal light, and the signal light emitting unit converts the signal light having a constant optical frequency and being turned on or off by the modulation signal into the code light of the code light emission procedure. The signal light emission procedure for outputting in synchronization and the combined light emission unit emit the code light emitted in the code light emission procedure and the signal light emission procedure. A combined light output procedure for combining optical signals at a timing at which the block of the temporal-optical frequency hopping spread code and the information signal are synchronized, and outputting the combined light to the optical transmission line, and the node In the receiving node, the optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light output procedure into an electrical signal, and receives the optical beat signal of the combined light, The temporal-optical frequency hopping spread code decoding unit determines an optical frequency of the temporal-optical frequency hopping spread code as a frequency difference between the optical frequency of the signal light emitting procedure and the optical frequency of the temporal-optical frequency hopping spread code. The component of the optical beat frequency for each chip time in the optical beat signal reception procedure according to the temporal-optical beat frequency spread code replaced with the optical beat frequency to be A temporal-optical frequency hopping spread code decoding procedure for decoding the optical beat signal of the signal light encoded by the temporal-optical frequency hopping spread code by extracting from the received optical beat signal; and an information signal The demodulating section includes an information signal demodulation procedure for demodulating the information signal from the optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding procedure.

  An optical frequency hopping code division multiplexing transmission method according to the present invention is an optical frequency hopping code division multiplexing transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes. At a transmitting node, a temporal-optical frequency hopping spread code storage unit stores a temporal-optical frequency hopping spread code in which optical frequencies orthogonal to each other are allocated for each chip time. A hopping spreading code storing procedure and a temporal-optical frequency hopping spreading code modulating unit in advance in the chip time according to the temporal-optical frequency hopping spreading code stored in the temporal-optical frequency hopping spreading code storing procedure. An optical frequency hopping signal that fluctuates the optical frequency in a predetermined time zone is set for each chip time. The optical frequency assigned to the temporal-optical frequency hopping spread code by the optical frequency hopping signal in the predetermined time zone is transmitted by the temporal-optical frequency hopping spread code modulation procedure Code light emission procedure for emitting signal light having a constant optical frequency in a time zone excluding the predetermined time zone within the chip time, and a signal light emission unit, The signal light emitted in the code light emission procedure is modulated on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, and the modulated signal light and the code light are emitted. A signal light emitting procedure, an optical branching unit that splits the signal light and the code light emitted in the signal light emitting procedure into two, respectively, and an optical delay unit that transmits the light The one of the signal light and the code light branched in the branching procedure is equal to or longer than the time width of the predetermined time zone so that the timing of emission of the code light coincides with the timing of emission of the signal light. An optical delay procedure for delaying by a time width less than the time width, and the combined light emitting unit, the signal light delayed by the optical delay procedure, the signal light and the other signal light branched by the optical branching unit, and An optical beat signal receiving unit includes: a combined light emitting procedure for combining the signal light and the combined light obtained by combining the signal light and the combined light to the optical transmission path; and a receiving node among the nodes. The optical beat signal reception procedure for photoelectrically converting the combined light emitted in the combined light emission procedure into an electrical signal and receiving the optical beat signal of the combined light, and the temporal-optical frequency hopping spread code decoding unit, Temporal A temporal-optical beat frequency spread code in which the optical frequency of the optical frequency hopping spread code is replaced with an optical beat frequency which is a frequency difference between the optical frequency of the signal light and the temporal-optical frequency hopping spread code; The signal light encoded by the temporal-optical frequency hopping spread code is extracted from the optical beat signal received in the optical beat signal reception procedure according to A temporal-optical frequency hopping spread code decoding procedure for decoding the optical beat signal, and an information signal demodulating section that receives the information signal from the optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding section. And an information signal demodulation procedure for demodulating the signal.

  An optical frequency hopping code division multiplexing transmission method according to the present invention is an optical frequency hopping code division multiplexing transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes. At a transmitting node, a temporal-optical frequency hopping spread code storage unit stores a temporal-optical frequency hopping spread code in which optical frequencies orthogonal to each other are allocated for each chip time. A hopping spreading code storing procedure and a temporal-optical frequency hopping spreading code modulating unit in advance in the chip time according to the temporal-optical frequency hopping spreading code stored in the temporal-optical frequency hopping spreading code storing procedure. An optical frequency hopping signal that fluctuates the optical frequency in a predetermined time zone is set for each chip time. The optical frequency assigned to the temporal-optical frequency hopping spread code by the optical frequency hopping signal in the predetermined time zone is transmitted by the temporal-optical frequency hopping spread code modulation procedure Code light emission procedure for emitting signal light having a constant optical frequency in a time zone excluding the predetermined time zone within the chip time, and a signal light emission unit, The signal light emitted in the code light emission procedure is modulated on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, and the modulated signal light and the code light are converted into the light. In the signal light emitting procedure for emitting to the transmission line and the receiving node among the nodes, the optical branching unit outputs the signal light and the coincident light emitted in the signal light emitting procedure. An optical branching procedure that branches into two, and an optical delay unit that outputs the one of the signal light and the code light branched in the optical branching procedure to the timing of emission of the code light and the output of the signal light. An optical delay procedure for delaying by a time width that is greater than or equal to the time width of the predetermined time zone and less than the time width of the chip time so that the timing matches, and the signal delayed by the combined light emitting unit by the optical delay procedure A combined light output procedure for combining the signal light and the encoded light, and the combined light obtained by combining the signal light and the encoded light; An optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light output procedure into an electrical signal and receives an optical beat signal of the combined light, and temporal-optical frequency hopping diffusion The code decoding unit A temporal-optical beat frequency spread code in which the optical frequency of the optical frequency hopping spread code is replaced with an optical beat frequency which is a frequency difference between the optical frequency of the signal light and the temporal-optical frequency hopping spread code; The signal light encoded by the temporal-optical frequency hopping spread code is extracted from the optical beat signal received in the optical beat signal reception procedure according to A temporal-optical frequency hopping spread code decoding procedure for decoding the optical beat signal, and an information signal demodulating section that receives the information signal from the optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding section. And an information signal demodulation procedure for demodulating the signal.

  In the optical frequency hopping code division multiplexing transmission method according to the present invention, the optical frequency hopping code division multiplexing transmission further transmits / receives an information signal by a plurality of radio base stations connected to the node through the optical transmission path and transmitting / receiving the information signal. In the method, in the radio base station that transmits among the radio base stations, an optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light emission procedure, and receives the optical beat signal of the combined light An optical beat signal receiving procedure, and a radio signal transmitting unit wirelessly transmitting an optical beat signal received in the optical beat signal receiving procedure, and receiving a radio base station out of the radio base stations In the station, the radio signal receiving unit receives the optical beat signal wirelessly transmitted by the radio signal transmitting procedure, and the base station emitting unit transmits the signal. Code light having an optical frequency obtained by adding the frequency of the optical beat signal received in the wireless signal reception procedure to the optical frequency of the signal light emitted in the light emission procedure, and the light of the signal light emitted in the signal light emission procedure It is preferable to have a base station emission procedure of combining signal light of a frequency and emitting the combined light to the optical transmission line. Since the combined light of the code light and the signal light is transmitted, if the optical frequency of the signal light and the code light is selected so that the optical beat signal is in the millimeter wave class, the wireless transmission can be easily incorporated into a part of the optical transmission line. be able to. Thereby, flexibility can be given to the form of the network.

  According to the present invention, in an optical code division multiplexing transmission, an information signal can be demodulated by receiving an optical beat signal, so that strict optical frequency control between nodes is not required. Therefore, it is possible to provide a network system that can transmit and receive information signals through an optical transmission line without using an expensive optical wavelength filter. Furthermore, since the optical beat signal component can be directly propagated in space, the function to be provided in the base station can be simplified even when part of the optical transmission path is wireless.

Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.
(Embodiment 1)
FIG. 1 is a configuration diagram illustrating an optical frequency hopping code division multiplexing transmission system according to the first embodiment. The optical frequency hopping code division multiplex transmission system 91 includes, for example, a PON (Passive Optical Network) in which n child nodes 81 ₁ to 81 _n and a parent node 82 are connected in an n-to-one manner by an optical transmission line 8. A network is formed. In the optical frequency hopping code division multiplexing transmission system 91, the optical directional coupler 7 and the optical transmission line 8 are shown in addition to the child node 81 ₁ to the child node 81 _n and the parent node 82. The network configuration is not limited to this. For example, although FIG. 1 shows a star type example in which the child nodes 81 ₁ to 81 _n are connected by one optical directional coupler 7, the present invention is not limited to this. In addition, a device for transmitting an optical signal such as a dispersion compensator or an amplifier may be provided in the optical transmission line 8. Hereinafter, a case where the child node 81 ₁ among the child nodes 81 ₁ to 81 _n transmits the information signal 51 ₁ represented by S ₁ (t) to the parent node 82 will be described.

Child node 81 _1, time - with optical frequency hopping spread code storing section 42, the time - with optical frequency hopping spread code modulation unit 4, the code-light emitting unit 3, an information signal modulation section 2, the signal light emission part 1 and the combined light emission part 41 are provided. Outgoing multiplexes light 57 of the multiplexed light emitting unit 41, the signal light 53 by the information signal 51 ₁ is first modulation, time - with optical frequency-hopping spread code 54 by the code light 56 which is secondary modulated, Is the combined light. When the combined light 57 is photoelectrically converted, an optical beat signal is generated. Child node 81 _1, the optical beat signal is characterized by performing frequency hopping so as to have an orthogonal relationship between the child nodes 81 ₁ to 81 _n.

Time - optical frequency hopping spread code storing section 42, time - is intended to perform optical frequency hopping spread code storing procedure, time specific to the child node 81 ₁ - storing optical frequency hopping spread code 54. Here, the temporal - the optical frequency hopping spread code 54, a spreading code is assigned in advance to the child node 81 _1, it is stored prior to transmission of the information signal expressed by S k _(t). Although FIG. 1 shows an example in which the temporal-optical frequency hopping spread code storage unit 42 is arranged outside the temporal-optical frequency hopping spread code modulation unit 4, the temporal-optical frequency hopping spread code modulation unit is shown. 4 may be incorporated.

  The temporal-optical frequency hopping spread code modulation unit 4 generates an optical frequency hopping signal 55 for changing the optical frequency of the coded light 56 in accordance with the temporal-optical frequency hopping spread code 54. Output every chip time. That is, the temporal-optical frequency hopping spread code modulation unit 4 performs a temporal-optical frequency hopping spread code modulation procedure. By outputting the optical frequency hopping signal 55 to the code light emitting unit 3, the code light emitting unit 3 performs secondary modulation by optical frequency hopping based on the temporal-optical frequency hopping spread code 54, and temporal-optical frequency. Coded light 56 having an optical frequency changed to the optical frequency assigned by the hopping spread code 54 is emitted. That is, the code light emitting unit 3 performs a code light emitting procedure. The code light emitting unit 3 is an optical frequency variable light source capable of changing the optical frequency of the code light 56 output by the optical frequency hopping signal 55 input from the temporal-optical frequency hopping spread code modulation unit 4. A light emitting element such as a semiconductor laser. Moreover, it is preferable that the code | cord light emission part 3 radiate | emits continuous light. In this embodiment, since the spread code is despread from the optical beat signal generated by the interference between the signal light 53 and the code light 56, the frequency difference between the signal light 53 and the code light 56 only needs to be stable. For this reason, precise control at the optical frequency level with a high-accuracy optical wavelength filter is unnecessary.

Information signal modulation section 2 in accordance with the information signal 51 _1, a modulation signal 52 for modulating the signal light 53 on or off, the time - and outputs for each block of the optical frequency hopping spread code 54. That is, the information signal modulation unit 2 performs an information signal modulation procedure. By outputting the modulation signal 52 to the signal light emitting unit 1, the signal light 53 emitted from the signal light emitting unit 1 can be primarily modulated by the information signal 51 ₁ represented by S _k (t). The signal light emitting unit 1 emits signal light 53 having a constant optical frequency and modulated on or off by a modulation signal 52. That is, the signal light emitting unit 1 performs a signal light emitting procedure. The signal light 53 is preferably continuous light. Further, it is preferable that the signal light emitting unit 1 easily emits the signal light 53 having a constant optical frequency even when the external environment such as temperature changes, and is, for example, a semiconductor laser.

  In the present embodiment, since the signal light 53 and the code light 56 are combined to perform spread encoding, the temporal-optical frequency hopping spread code modulation unit 4 outputs the optical frequency hopping signal 55 at a timing. The timing at which the information signal modulator 2 outputs the modulation signal 52 is synchronized with the clock of the optical frequency hopping code division multiplexing transmission system 91. The timing at which the code light emitting unit 3 emits the code light 56 and the timing at which the signal light emitting unit 1 emits the signal light 53 are synchronized. The timing adjustment mechanism of the optical frequency hopping code division multiplexing transmission system 91 is omitted.

The combined light emitting unit 41 combines the code light 56 emitted from the code light emitting unit 3 and the signal light 53 emitted from the signal light emitting unit 1, and outputs the combined light 57 to the optical transmission path 8. That is, the combined light emitting unit 41 performs a combined light emitting procedure. Here, it is preferable that the multiplexed light emitting unit 41 multiplexes the code light 56 and the signal light synchronized with each block of the temporal-optical frequency hopping spread code 54. Therefore, the child node 81 _1, the timing of the code light 56 to be input to the multiplexing-light emitting unit 41, and the timing of the signal light 53 to be input to the multiplexing-light emitting unit 41, a time - for optical frequency-hopping spread code 54 It is preferable to further include a timing adjustment unit (not shown) for matching each block. By further comprising a timing adjusting unit prevents shift of the timing at the time of multiplexing the codes beam and a signal beam, the information signal 51 temporally for each modulated signal light on or off in response to the ₁ - optical frequency An optical beat signal encoded with the hopping spread code 54 can be generated.

  The timing adjustment unit adjusts, for example, the timing at which the temporal-optical frequency hopping spread code modulation unit 4 outputs the optical frequency hopping signal 55 and the timing at which the information signal modulation unit 2 outputs the modulation signal 52. The timing of the code light 56 input to the combined light output unit 41 and the timing of the signal light 53 input to the combined light output unit 41 are matched for each block of the temporal-optical frequency hopping spread code 54. Further, the timing adjustment unit delays at least one of the code light 56 emitted from the code light emission unit 3 and the signal light 53 emitted from the signal light emission unit 1 and inputs the code light 56 input to the combined light emission unit 41. And an optical delay line that matches the timing of the signal light 53 input to the multiplexed light emitting unit 41 for each block of the temporal-optical frequency hopping spread code 54.

Furthermore, the child node ₈₁₁ detects the optical beat signal in the light detector 5 is taken out a portion of the combined light 57, the temporal order to constant the transmission output of the band pass filter 6 - optical frequency hopping spread code modulation unit By feeding back to 4, it is possible to stabilize the signal output of the optical beat signal received by the optical beat signal receiving unit 9 constant.

Multiplexed light 57 ₁ for emitting the combined light emitting portion 41 is further combined with multiplexed light ₅₇ 2 to 57 _n from the optical directional coupler 7 child node ₈₁ 2 to 81 _n propagated through the optical transmission line 8 The parent node 82 is reached. In the parent node 82, the optical beat signal receiving unit 9 photoelectrically converts the combined light 57 emitted from the combined light emitting unit 41 into an electrical signal, and receives the optical beat signal 61 of the combined light 57. That is, the optical beat signal receiving unit 9 performs an optical beat signal receiving procedure. The amplifier 10 outputs an optical beat signal 62 obtained by selectively amplifying an intermediate frequency component that is a component of the optical beat signal 61 among the electrical signals output from the optical beat signal receiving unit 9. The distributor 11 distributes the optical beat signal 62 by the number n of the child nodes 81 _{1 to} 81 _n .

The temporal-optical frequency hopping spreading code decoding units 12 _{1 to} 12 _n assign the optical beat signal 63 distributed by the distributor 11 to the temporal-optical frequency hopping assigned to each of the child nodes 81 ₁ to 81 _n. time corresponding to the spreading code 54 specific - n number of time based on the optical beat frequency spreading code - is decrypted with the optical frequency-hopping spread code decoding unit 12 ₁ to 12 _n. That is, the temporal-optical frequency hopping spreading code decoding units 12 _{1 to} 12 _n perform a temporal-optical frequency hopping spreading code decoding procedure. For example, the temporal-optical frequency hopping spreading code decoding unit 12 ₁ uses the optical beat signal based on the temporal-optical beat frequency spreading code corresponding to the temporal-optical frequency hopping spreading code 54 assigned to the child node 81 _1. 63 is decrypted. Here, the temporal-optical beat frequency spreading code is obtained by calculating the optical frequency of the temporal-optical frequency hopping spreading code 54 between the optical frequency of the signal light emitting unit 1 and the optical frequency of the temporal-optical frequency hopping spreading code 54. It is a code for despreading that is replaced with an optical beat frequency that is a frequency difference.

The information signal demodulation units 13 _{1 to} 13 _n perform primary modulation on the electrical signals 64 ₁ to 64 _n obtained by decoding of the temporal-optical frequency hopping spread code decoding units 12 _{1 to} 12 _n to perform information signals 51 _{1 to} 51 _n. demodulating the _n, it outputs the information signal 51 ₁ need to be represented by _S k (t). That is, the information signal demodulation units 13 _{1 to} 13 _n perform an information signal demodulation procedure. For example, the information signal demodulator 13 _1, time - to demodulate the optical beat signal 64 ₁ by decoding the optical frequency hopping spread code decoding unit 12 ₁ to the information signal 51 _1.

Temporal-optical frequency hopping spread code decoding units 12 _{1 to} 12 _n receive the optical beat frequency component for each chip time of the temporal-optical beat frequency spread code from the optical beat signal 61 received by the optical beat signal receiving unit 9. Extract. In this way, the optical beat signal 63 of the signal light 53 encoded by the temporal-optical frequency hopping spread code 54 is decoded by performing despread frequency filtering using the temporal-optical beat frequency spread code. can do. In the decoding from the optical beat signal 63, it is sufficient that the child nodes 81 ₁ to 81 _n and the parent node 82 are stable at the beat signal frequency much lower than the optical frequency. Can be realized.

As described above, in the PON network in which the child nodes 81 ₁ to 81 _n and the parent node 82 are connected in an n-to-one manner, the wavelength or frequency of light at each transmission / reception node required for encoding is highly accurate. The child nodes 81 ₁ to 81 _n and the parent node 82 only need to be stable at a frequency of the optical beat signal that is much lower than the optical frequency, so that the filter characteristics are changed according to the situation. It is rich in flexibility. For example, when applied to a PON network used for FTTH, transmission up to about 100 Gb / s can be performed as a total capacity (= number of nodes × capacity) without changing the PON network shape at all. In addition, when a part of the transmission path between the transmitting and receiving nodes is replaced with radio, the optical beat signal component can be directly spatially propagated as optical radio (ROF) by an EA modulator or the like. Compared with, the base station function can be greatly simplified.

FIG. 2 is an explanatory diagram illustrating an example of a modulated signal and a temporal-optical frequency hopping spread signal. Time allocated to child node indicated 81 ₁ in Figure 1 - an example of an optical frequency hopping spread code, for ease of understanding, as shown in a matrix of time factor and the frequency component. In the temporal-optical frequency hopping spreading code, the optical frequencies f _k orthogonal to each other between the child nodes 81 ₁ to 81 _n shown in FIG. 1 are assigned for each chip time T _chip . In this embodiment, since there are n child nodes 81 ₁ to 81 _n , the spreading code length is a variation of n frequencies, and the optical frequency f _k (k = 1 to n) every n chip times. An example in which “1” is given to any of the above is shown. In accordance with this temporal-optical frequency hopping spreading code, an optical frequency hopping signal 55 for changing the optical frequency f _k of the code light 56 is output every chip time T _chip . FIG. 2 shows an example in which “10101... 1” is changed for each chip time T _chip and optical frequency. As described above, the optical frequency of the encoded light of the child node 81 ₁ varies for each chip time T _chip , and the optical frequency for each chip time T _chip is a different child node 81 _k (k = 2 to n). ), The beat signal of the combined light of the signal light of the center frequency f _L and the code light of the optical frequency f _k (k = 1 to n) is extracted for each chip time, and the extracted signal output Is integrated over the block of the temporal-optical frequency hopping spreading code, it is determined whether the modulation signal 52 that modulates the signal light 53 combined with the code light 56 is on or off. be able to. Whether the modulation signal of the signal light on the transmission side is on or off is discriminated based on a threshold value, and the information signal 51 of 1 or 0 can be demodulated according to the on or off.

FIG. 3 is a graph showing an example of an optical frequency hopping signal. For example, if the code light emitting unit 3 is a semiconductor laser (LD), the temporal-optical frequency hopping spread code modulation unit 4 outputs an optical frequency hopping signal 55 of a drive current corresponding to the optical frequency output by the code light 56. Output. The temporal-optical frequency hopping spread code modulating unit 4 drives the coded light emitting unit 3 with a current that modulates light having a predetermined optical frequency by the temporal-optical frequency hopping spread code 54. The code light 56 emitted from the code light emitting unit 3 hops in the center optical frequency in accordance with the drive current of the optical frequency hopping signal 55 output from the temporal-optical frequency hopping spread code modulation unit 4, and at the chip time T _chip . Change over time. The drive current output from the temporal-optical frequency hopping spread code modulation unit 4 at this time has a rectangular multi-valued two-dimensional distribution as shown in FIG. 3, for example.

FIG. 4 is a pick-up diagram of the parent node. FIG. 5 is a graph showing an example of an optical beat signal received by the parent node. Multiplexed light 57 is photoelectrically converted by the optical beat signal receiving unit 9, an intermediate frequency band from the frequency which is the frequency component of the optical beat signal at the intermediate frequency amplifier 10 (f L _{-f 1)} to the frequency (f L _{-f n)} Is extracted and enters the bandpass filter 14. The optical beat components included in the output signal 66 from the optical beat signal receiving unit 9 are transmitted and transmitted through the band-pass filter 14 in which the transmittance is set for each chip time based on the temporal-optical beat frequency spread code. Is output and differentially amplified by the differential amplifier 15. Thereby, the optical beat signal encoded with the temporal-optical frequency hopping spread code can be extracted for each chip time. The extracted optical beat signal for each chip time is differentially amplified by a differential amplifier 15 and integrated by an integrator 16 over a block of temporal-optical frequency hopping spread codes. If the optical beat signal integrated by the integrator 16 exceeds a predetermined threshold value, the information signal demodulating unit 13 demodulates the information signal to “1”, for example, as the signal light 53 modulated on on the transmission side. . On the other hand, if the value integrated by the integrator 16 is equal to or smaller than a predetermined threshold, the information signal demodulating unit 13 demodulates the information signal to, for example, “0”. Here, the integrator 16 may be a low-pass filter that determines fluctuations in signal output in units of temporal-optical frequency hopping spreading codes.

FIG. 5 shows the characteristics of the bandpass filter 14. FIG. 5 shows a case where the temporal-optical frequency hopping spreading code is “10101... 1” in order of the optical frequency and the chip time, and the light transmitting region of the bandpass filter 14 is indicated by a dotted line. Thus, of the frequency components of the optical beat signal for each optical frequency f _k (k = 1 to n), the frequency (f _L −f ₁ ) and frequency (f _L − f ₃ ), frequency (f _L −f ₅ ),... frequency (f _L −f _n ) are sequentially transmitted every chip time, and other regions are not transmitted. The frequency interval between adjacent beat signals is, for example, the bandwidth of the information signal. The extraction of the frequency of the optical beat signal whose spreading code is 1 is the frequency (f _L −f ₁ ), the frequency (f _L −f ₃ ), the frequency (f _L −f ₅ ),... The frequency (f _L The optical beat signal may be extracted by a filter that transmits −f _n ), and the extracted optical beat signal may be decoded by a switch that selects each chip time.

In the first embodiment described above, an example has been described for transmitting from the child node 81 ₁ to the parent node 82 of the information signal, transmits the information signal from one of the child nodes 81 _{k (k} = 1~n) to the parent node 82 May be. Further, the information signal may be transmitted from the parent node 82 to any of the child nodes 81 _k (k = 1 to n). For example, a parent node 82 the signal light emission part, information signal modulation section, code-light emitting unit, time - with optical frequency hopping spread code modulation unit, the child node ₈₁₁ is an optical beat signal receiver, time - optical frequency By providing the hopping spreading code decoding unit and the information signal demodulating unit, it is possible to transmit the information signal from the parent node 82 to the child node 81 _k (k = 2 to n).

(Embodiment 2)
FIG. 6 is a block diagram showing an optical frequency hopping code division multiplexing transmission system according to this embodiment. The case where the information signal 51 ₁ is transmitted from the child node 83 ₁ to the parent node 84 in the optical frequency hopping code division multiplexing transmission system 92 shown in FIG. 6 will be described. Child node 83 _1, time - provided with an optical frequency-hopping spread code modulating portion 16, a code-light emitting unit 17, the signal light output unit 19, a - and optical frequency-hopping spread code storing section 42, time. Unlike the optical frequency hopping code division multiplexing transmission system 91, the present embodiment is characterized in that the signal light 53 and the code light 56 are allocated to different time zones within one chip time instead of the combined light. To do. The optical frequency hopping code division multiplexing transmission system 91 that simultaneously generates the signal light 53 and the code light 56 within one chip time requires a light source connected in parallel, whereas the optical frequency hopping code division multiplexing transmission system 92 requires one light source. It is characterized by being configurable.

The temporal-optical frequency hopping spread code modulation unit 16 varies the optical frequency hopping signal for changing the optical frequency in a predetermined time zone within the chip time in accordance with the temporal-optical frequency hopping spread code 54 described in FIG. 55 is output every chip time. That is, the temporal-optical frequency hopping spread code modulation unit 16 performs temporal processing according to the temporal-optical frequency hopping spread code 54 in which optical frequencies orthogonal to each other among the child nodes 83 _{1 to} 83 _n are allocated for each chip time. -Perform optical frequency hopping spread code modulation procedure. The code light emitting unit 17 having the center frequency f ₀ is subjected to the temporal-optical frequency hopping spread code 54 by the temporal-optical frequency hopping spread code modulating unit 16 for a predetermined time zone in which the optical frequency hopping signal 55 is input. The code light 56 that fluctuates to the assigned optical frequency is emitted. On the other hand, in the time zone in which the optical frequency hopping signal 55 is not input, the signal light 58 with the center frequency f ₀ having a constant optical frequency is emitted. That is, the code light emitting unit 17 performs a code light emitting procedure. The signal light emitting unit 19 outputs the signal light 58 of the code light 56 and the signal light 58 for each block of the temporal-optical frequency hopping spread code according to the information signal 51 represented by S ₁ (t). Primary modulation is performed on or off, and the modulated signal light 53 is emitted. That is, the signal light emitting unit 19 performs a signal light emitting procedure. Here, it is preferable that the signal light emitting unit 19 emits the signal light 53 and the matching light 56 in accordance with the time zone within the chip time. Sign light 56 and signal light 53 is emitted from the child node 83 ₁ to the optical transmission line 8, it is transmitted by the optical transmission line 8.

The combined light 56 and signal light 53 emitted from each of the child nodes 83 ₁ to 83 _n are combined by the optical directional coupler 7, propagated through the optical transmission line 8, and reach the parent node 84. Each of the optical beam 56 and the signal light 53 reaching the parent node 84 is branched into two by the optical branching unit 20a. That is, the optical branching unit 20a performs the optical branching procedure. Then, one encoded light 56 and the signal light 53 branched by the optical branching unit 20a enter the combined light emitting unit 20b via the optical delay unit 21, and the other encoded light 56 branched by the optical branching unit 20a. And the signal light 53. That is, the optical delay unit 21 performs an optical delay procedure, and the combined light output unit 20b performs a combined light output procedure. It is preferable that both the optical branching unit 20a and the combined light emitting unit 20b use an optical directional coupler. The processing after the combined light emitted from the combined light emitting unit 20b enters the optical beat signal receiving unit 9 is the same as that of the optical frequency hopping code division multiplexing transmission system 91 described above. That is, the optical beat signal receiving unit 9 performs the optical beat signal receiving procedure, and the temporal-optical frequency hopping spread code decoding units 12 _{1 to} 12 _n perform the temporal-optical frequency hopping spread code decoding procedure, thereby demodulating the information signal. Units 13 _{1 to} 13 _n perform an information signal demodulation procedure.

Here, the optical delay unit 21 uses the code light emitting unit 17 so that the timing of the code light 56 and the timing of the signal light 53 match the one of the code light 56 and the signal light 53 branched by the optical branching unit 20a. Is delayed by a time width not less than the time width of the chip time and not less than the time width of the predetermined time zone for emitting the code light. Since the chip time can be used effectively, the predetermined time zone is preferably the first half or the second half of the chip time T _chip . For example, if the predetermined time zone is the first half of the chip time, when the first half of the chip time T _chip is modulated with the code light 56 and the second half of the chip time T _chip is modulated with the signal light 53, the optical delay unit 21 However, by delaying the code light 56 and the signal light 53 by a half cycle of the chip time T _chip , it is possible to generate a combined light 57 obtained by combining the code light 56 and the signal light 53. The optical delay unit 21 is, for example, an optical fiber delay line. The optical branching section 20a for generating a multiplexed light 57, optical delay unit 21 and the multiplexed light exit portion 20b is not in the parent node 84, is provided downstream of the signal light output unit 17 of the child node 83 ₁ Also good.

FIG. 7 is an explanatory diagram illustrating an example of an information signal and a temporal-optical frequency hopping spread signal according to the second embodiment. Time in Figure 6 are assigned to the child node indicated 83 ₁ - which is an example of an optical frequency hopping spread code. The difference from the temporal-optical frequency hopping spreading code described with reference to FIG. 2 is that the optical frequency value in which the center optical frequency is constant frequency f ₀ and the optical frequency hopping is repeated alternately within one chip time T _chip . It is. FIG. 8 is a graph showing an example of an optical frequency hopping signal. When the code light emitting unit 17 is an LD and the information signal and the temporal-optical frequency hopping spread code shown in FIG. 7 are used, for example, the optical frequency hopping signal is a rectangular multi-value with a constant value i ₀ in between. Drive current. Unlike the case of FIG. 2, in this example, the drive current is about twice as fast, so the hopping frequency is doubled. The optical frequency f ₀ is obtained when the chip time T _chip is ½, and the optical delay signal can be received by the optical delay unit 21 by delaying the chip time T _chip by ½ of the chip time T _chip. it can. When the temporal-optical frequency hopping spread code 54 is “10101... 1” for each chip time T _chip and optical frequency, the optical beat signal is such that the optical frequency f _L in FIG. 5 is the optical frequency f _0. Peaks appear at frequencies (f ₀ -f ₁ ), (f ₀ -f ₃ ), (f ₀ -f ₅ ), ... (f ₀ -f _n ). Since frequency hopping is performed at twice the speed, in this case, the bandwidth of the signal having each beat signal as a carrier is about twice that of FIG. Regarding the decoding function, decoding can be performed with the same configuration and procedure as in FIG.

In a similar configuration as FIG. 6, the optical frequency deviation of the code light 56 rather than the half of the chip time _{T Chip,} may be a chip time _{T Chip.} For example, this corresponds to the case where the state of the optical frequency f ₀ is eliminated in FIG. 7, and the optical beat signal between the optical frequencies of the temporal-optical frequency hopping spread code in the adjacent chip time is represented by the temporal-optical frequency hopping spread code. The decryption unit decrypts. In this case, the delay time of the optical delay unit 21 is set to T _chip by making the frequency of the optical beat signal between the optical frequencies of the temporal-optical frequency hopping spread codes in adjacent chip times orthogonal to each other. However, an optical beat signal between adjacent hopping frequencies can be obtained. In this case, demodulation is possible with the same configuration and procedure as in FIG.

In the above embodiment 2, an example has been described for transmitting a child node 83 information signals from _one to the parent node 84, transmits the information signal from one of the child nodes 83 _{k (k} = 1~n) to the parent node 84 May be. Further, the information signal may be transmitted from the parent node 84 to any of the child nodes 83 _k (k = 1 to n). For example, a parent node 84 the signal light emission part, information signal modulation section, code-light emitting unit, time - with optical frequency hopping spread code modulation unit, the child node 83 ₁ is an optical beat signal receiver, time - optical frequency By including the hopping spread code decoding unit and the information signal demodulating unit, it is possible to transmit the information signal from the parent node 84 to the child node 83 _k (k = 2 to n).

(Embodiment 3)
FIG. 9 is a block diagram showing an optical frequency hopping code division multiplexing transmission system according to this embodiment. The case where a part of transmission path sections is made wireless is shown. Optical frequency hopping code division multiplex transmission system 93 shown in FIG. 9, between the child node 85 ₁ and the parent node 86, are connected with the child node 85 ₁ and the parent node 86 and the optical transmission path 24 and 33, the information signal 51 Are provided with a plurality of radio base stations 87 _{1 to} 87 ₂ . The radio base station 87 ₁ is connected to the child node 85 _{1 through the} optical transmission line 24. The radio base station 87 ₂ is connected to the parent node 86 in the optical transmission path 32. FIG. 9 shows the case where the uplink between the child node 85 ₁ and the parent node 86 is wireless, but the uplink between any of the child nodes 85 _k (k = 2 to n) and the parent node 86. May be down or down.

The child nodes 85 _{1 to} 85 _n have the same configuration as the child nodes 81 _{1 to} 81 _{n in} FIG. The parent node 86 has the same configuration as the parent node 82 in FIG. Outgoing multiplexes light 57 of the child node 85 ₁ through the optical transmission path 24, and reaches the radio base station 87 ₁ of the child node 85 _1. In the radio base station 87 ₁ , the optical beat signal receiving unit 25 photoelectrically converts the combined light 57 emitted from the combined light emitting unit of the child node 85 ₁ and receives the optical beat signal of the combined light 57. That is, the optical beat signal receiving unit 25 performs an optical beat signal receiving procedure. Here, the frequency of the optical beat signal received by the optical beat signal receiving unit 25 is preferably a wavelength band in which wireless transmission is possible. For example, if the frequency of the optical beat signal is from the quasi-millimeter to millimeter-wave band, ROF (Radio On Fiber) technology for converting light and radio can be applied. A configuration for receiving electrical signals in the optical frequency band and a configuration for wireless transmission such as an oscillator of a carrier wave because the frequency difference between the signal light and the coded light is a frequency band that allows direct wireless transmission. Can be largely omitted.

The optical beat signal 71 received by the optical beat signal receiving unit 25 is amplified by the amplifier 26 while maintaining the frequency. Then, the wireless signal transmission unit 27 wirelessly transmits the optical beat signal 71. That is, the wireless signal transmission unit 27 performs a wireless signal transmission procedure. The radio signal transmission unit 27 is an antenna that transmits and receives radio signals by radio waves, for example. Optical beat signal 71 transmitted by the radio signal transmitting unit 27 is received by the parent node 86 side of the radio base station 87 ₂ of the radio signal reception section 28. That is, the radio signal receiving unit 28 performs an optical beat signal receiving procedure. The optical beat signal 71 received by the wireless signal receiving unit 28 is amplified by the amplifier 29. Then, the base station emitting unit 30 modulates each of the optical frequencies f _{1 to} f _n from the light source 31 to on or off in accordance with the frequency of the optical beat signal 71, and combines with the light of the optical frequency f _L from the light source 31. to generate waves were multiplexed light, to reproduce the multiplexed light 57 incident to the radio base station 87 _1. The base station emitting unit 30 emits light to the optical transmission path 32 connected to the receiving parent node 86. That is, the base station emitting unit 30 performs a base station emitting procedure. Multiplexed light 57 emitted to the optical transmission line 32, leading to a parent node 86 through the optical directional coupler 33 _2. The processing in the parent node 86 is the same as the processing in the parent node 82 described in FIG.

Base station emission unit 30 includes an optical frequency _f 1 ~f _n obtained by adding the reception frequency of the optical beat signal 71 of the radio signal reception section 28 to the optical frequency _{f L} of the signal light, which is common in the child node ₈₅ 1 to 85 _n Are combined with the signal light having the optical frequency f _L of the signal light, and the combined light 57 is output to the optical transmission line 32 connected to the receiving parent node 86. The optical beat signal 71 includes an optical beat signal having a frequency difference between each of the optical frequencies f _{1 to} f _n and the optical frequency f _L. For this reason, the light according to the frequency (f _L −f ₁ ), frequency (f _L −f ₃ ), frequency (f _L −f ₅ ),... Frequency (f _L −f _n ) of the optical beat signal 71. The frequency combined light 57 is modulated and emitted. For example, if the frequency (f _L −f ₁ ) is included in the optical beat signal 71, the base station emitting unit 30 emits the combined light 57 of the encoded light having the optical frequency f ₁ and the signal light having the optical frequency f _L. To do. And an optical frequency _{f L} of the signal light emission of each child node ₈₅ 1 to 85 _n, and an optical frequency _f 1 ~f _n symbols light emission of each child node ₈₅ 1 to 85 _n, since is common, If the light source 31 emits n multiplexed lights 57 having different optical frequencies, the base station emitting unit 30 performs primary modulation according to on or off for each frequency included in the optical beat signal 71, thereby each child node. The combined light 57 emitted from 85 _{1 to} 85 _n can be reproduced. Here, the base station emitting unit 30 is, for example, an electroabsorption modulator. The light source 31 includes, for example, n light emitting elements that emit optical frequencies f _{1 to} f _n . The light source 31 may be a super continuum light source.

When the radio is applied in the configuration example of the optical frequency hopping code division multiplexing transmission system according to the second embodiment illustrated in FIG. 6, the optical branching unit 20a, the optical delay unit 21, and the combined light emitting unit 20b are connected to the parent node 84 side. In addition, since the multiplexed light 57 propagates through the optical transmission line 8 by providing it at the subsequent stage of the signal light emitting unit 19 of each of the child nodes 83 ₁ to 83 _n , it is possible to wirelessly use the same configuration as in FIG. .

  Since the present invention can perform despreading frequency filtering with an electric filter, the system configuration can be simplified. Further, since the optical beat signal component can be directly spatially propagated as optical radio (ROF), the base station function can be greatly simplified as compared with normal radio.

1 is a configuration diagram showing an optical frequency hopping code division multiplexing transmission system according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating an example of a modulation signal and a temporal-optical frequency hopping signal in the first embodiment. 3 is a graph illustrating an example of an optical frequency hopping signal in the first embodiment. It is a pick-up figure of a parent node. It is a graph which shows an example of the optical beat signal which a parent node receives. It is a block diagram which shows the optical frequency hopping code division multiplexing transmission system which concerns on Embodiment 2. FIG. 6 is an explanatory diagram illustrating an example of a modulation signal and a temporal-optical frequency hopping signal in Embodiment 2. FIG. 6 is a graph showing an example of an optical frequency hopping signal in the second embodiment. It is a block diagram which shows the optical frequency hopping code division multiplexing transmission system which concerns on Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 19 Signal light emission part 2 Information signal modulation part 3, 17 Code light emission part 4, 16 Temporal-light frequency hopping spread code modulation part 5 Optical detector 6 Band pass filter 7 Optical directional coupler 8 Optical transmission line DESCRIPTION OF SYMBOLS 9 Optical beat signal receiving part 10 Amplifier 11 Divider 12 Temporal-optical frequency hopping spreading code decoding part 13 Information signal demodulating part 14 Band pass filter 15 Differential amplifier 16 Integrator 20a Optical branching part 20b Combined light emitting part 21 Optical delay Units 24 and 32 Optical transmission line 25 Optical beat signal receiving unit 26 Amplifier 27 Radio signal transmitting unit 28 Radio signal receiving unit 29 Amplifier 30 Base station emitting unit 31 Light source 33 Optical directional coupler 41 Combined light emitting unit 42 Temporal-light Frequency hopping spread code storage unit 51 Information signal 52 Modulated signal 53 Signal light 54 Temporal-optical frequency hopping spread code 55 Optical frequency hopping signal 56 Coded light 57 Combined light 58 Signal light 61, 62, 63, 71 Optical beat signal 64 Optical beat signal decoded according to temporal-optical beat frequency spread code 65 Demodulated information signal 66 Optical beat signal reception Signal 81, 83, 85 Child node 82, 84, 86 Parent node 87 ₁ , 87 ₂ Radio base station 91, 92, 93 Optical frequency hopping code division multiplexing transmission system

Claims (9)

An optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line and transmits and receives information signals between the nodes,
Among the nodes, the transmitting node is
A temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading codes in which optical frequencies orthogonal to each other between the nodes are assigned for each chip time;
Temporal-optical frequency hopping for outputting an optical frequency hopping signal for changing an optical frequency for each chip time according to the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage unit A spreading code modulator;
A code light emitting unit that emits code light of an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spreading code by the optical frequency hopping signal;
An information signal modulator that outputs a modulation signal that is modulated on or off according to the information signal for each block of the temporal-optical frequency hopping spreading code;
A signal light emitting unit that emits signal light having a constant optical frequency and modulated on or off by the modulation signal;
A combined light emitting unit for combining the coded light emitted from the coded light emitting unit and the signal light emitted from the signal light emitting unit, and emitting the combined light to the optical transmission path,
Among the nodes, the receiving node is
An optical beat signal receiving unit that photoelectrically converts the combined light emitted from the combined light output unit into an electrical signal and receives an optical beat signal of the combined light;
Temporal-light in which the optical frequency of the temporal-optical frequency hopping spread code is replaced with an optical beat frequency that is a frequency difference between the optical frequency of the coded light emitting unit and the optical frequency of the temporal-optical frequency hopping spread code According to the beat frequency spread code, the component of the optical beat frequency for each chip time is extracted from the optical beat signal received by the optical beat signal receiver, and is encoded by the temporal-optical frequency hopping spread code. A temporal-optical frequency hopping spread code decoding unit for decoding an optical beat signal of the signal light,
An information signal demodulating unit that demodulates the information signal from the optical beat signal of the signal light that is decoded by the temporal-optical frequency hopping spread code decoding unit;
An optical frequency hopping code division multiplexing transmission system. An optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line and transmits and receives information signals between the nodes,
Among the nodes, the transmitting node is
A temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading codes in which optical frequencies orthogonal to each other between the nodes are assigned for each chip time;
An optical frequency hopping signal for changing an optical frequency in a predetermined time zone within the chip time in accordance with the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage unit. A temporal-optical frequency hopping spread code modulator that outputs every chip time;
In the predetermined time zone, the optical frequency hopping signal emits code light having an optical frequency changed to the optical frequency assigned by the temporal-optical frequency hopping spread code, and the predetermined time zone within the chip time is emitted. In a time zone excluding, a code light emitting unit that emits signal light having a constant optical frequency;
The signal light emitted from the code light emitting unit is modulated on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, and the modulated signal light and the code light are emitted. A signal light emitting part;
An optical branching unit that splits the signal light and the code light emitted by the signal light emitting unit into two, respectively;
For the one of the signal light and the code light branched by the optical branching unit, the chip has a time width of the predetermined time period or longer so that the timing of emission of the code light coincides with the timing of emission of the signal light An optical delay unit that delays by a time width less than the time width of time,
The signal light and the combined light delayed by the optical delay unit are combined with the other signal light and the encoded light branched by the optical branching unit, and the combined signal light and the combined light are combined. A combined light emitting unit for emitting wave light to the optical transmission path,
Among the nodes, the receiving node is
An optical beat signal receiving unit that photoelectrically converts the combined light emitted from the combined light output unit into an electrical signal and receives an optical beat signal of the combined light;
Temporal-optical beat in which the optical frequency of the temporal-optical frequency hopping spreading code is replaced with an optical beat frequency that is a frequency difference between the optical frequency of the signal light and the optical frequency of the temporal-optical frequency hopping spreading code. According to the frequency spread code, the component of the optical beat frequency for each chip time is extracted from the optical beat signal received by the optical beat signal receiver, and is encoded by the temporal-optical frequency hopping spread code. A temporal-optical frequency hopping spread code decoding unit for decoding the optical beat signal of the signal light;
An information signal demodulating unit that demodulates the information signal from the optical beat signal of the signal light that is decoded by the temporal-optical frequency hopping spread code decoding unit;
An optical frequency hopping code division multiplexing transmission system. An optical frequency hopping code division multiplexing transmission system in which a plurality of nodes are connected by an optical transmission line and transmits and receives information signals between the nodes,
Among the nodes, the transmitting node is
A temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading codes in which optical frequencies orthogonal to each other between the nodes are assigned for each chip time;
An optical frequency hopping signal for changing an optical frequency in a predetermined time zone within the chip time in accordance with the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage unit. A temporal-optical frequency hopping spread code modulator that outputs every chip time;
In the predetermined time zone, the optical frequency hopping signal emits code light having an optical frequency changed to the optical frequency assigned by the temporal-optical frequency hopping spread code, and the predetermined time zone within the chip time is emitted. In a time zone excluding, a code light emitting unit that emits signal light having a constant optical frequency;
The signal light emitted from the code light emitting unit is modulated on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, and the modulated signal light and the code light are converted into the light. A signal light emitting part that emits to the transmission line,
Among the nodes, the receiving node is
An optical branching unit that splits the signal light and the code light emitted by the signal light emitting unit into two parts, respectively;
For the one of the signal light and the code light branched by the optical branching unit, the chip has a time width of the predetermined time period or longer so that the timing of emission of the code light coincides with the timing of emission of the signal light An optical delay unit that delays by a time width less than the time width of time,
The signal light and the combined light delayed by the optical delay unit and the other signal light and the combined light branched by the optical branching unit are combined, and the combined light obtained by combining the signal light and the combined light A combined light emitting part for emitting
An optical beat signal receiving unit that photoelectrically converts the combined light emitted from the combined light output unit into an electrical signal and receives an optical beat signal of the combined light;
Temporal-optical beat in which the optical frequency of the temporal-optical frequency hopping spreading code is replaced with an optical beat frequency that is a frequency difference between the optical frequency of the signal light and the optical frequency of the temporal-optical frequency hopping spreading code. According to the frequency spread code, the component of the optical beat frequency for each chip time is extracted from the optical beat signal received by the optical beat signal receiver, and is encoded by the temporal-optical frequency hopping spread code. A temporal-optical frequency hopping spread code decoding unit for decoding the optical beat signal of the signal light;
An information signal demodulating unit that demodulates the information signal from the optical beat signal of the signal light that is decoded by the temporal-optical frequency hopping spread code decoding unit;
An optical frequency hopping code division multiplexing transmission system. A plurality of radio base stations connected to the node via the optical transmission line and transmitting and receiving the information signal;
Among the wireless base stations, the transmitting wireless base station is
An optical beat signal receiving unit that photoelectrically converts the combined light emitted by the combined light emitting unit and receives an optical beat signal of the combined light;
A wireless signal transmitter that wirelessly transmits an optical beat signal received by the optical beat signal receiver;
The radio base station that receives the radio base station is:
A radio signal receiver for receiving an optical beat signal transmitted by radio from the radio signal transmitter;
Code light having an optical frequency obtained by adding the frequency of the optical beat signal received by the wireless signal receiving unit to the optical frequency of the signal light emitted by the signal light emitting unit, and the signal light emitted by the signal light emitting unit Base station emitting unit for combining the signal light of the optical frequency, and emitting the combined light to the optical transmission path,
The optical frequency hopping code division multiplexing transmission system according to claim 1 or 2, further comprising: A timing adjustment unit that matches the timing of the coded light input to the combined light output unit and the timing of the signal light input to the combined light output unit for each block of the temporal-optical frequency hopping spread code; In addition to the previous stage of the combined light emitting unit,
2. The optical frequency hopping code according to claim 1, wherein the multiplexed light emitting unit multiplexes the code light and the signal light synchronized for each block of the temporal-optical frequency hopping spread code. Division multiplexing transmission system. An optical frequency hopping code division multiplex transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes,
In the transmitting node among the nodes,
Temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other between nodes are allocated every chip time. When,
The temporal-optical frequency hopping spread code modulator transmits an optical frequency hopping signal for changing an optical frequency according to the temporal-optical frequency hopping spread code storage procedure stored in the temporal-optical frequency hopping spread code storage procedure to the chip time. A temporal-optical frequency hopping spreading code modulation procedure for each output;
A code light emitting unit, wherein the code light emitting unit emits code light of an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spread code by the optical frequency hopping signal;
An information signal modulation unit modulates the modulated signal that is turned on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, in the optical frequency hopping of the temporal-optical frequency hopping spread code modulation procedure. An information signal modulation procedure for outputting in synchronization with the signal;
A signal light emitting step for emitting signal light having a constant optical frequency and being modulated on or off by the modulation signal in synchronization with the code light of the code light emitting procedure;
The combined light emission unit outputs the code light emitted in the code light emission procedure and the signal light emitted in the signal light emission procedure at a timing at which the block of the temporal-optical frequency hopping spread code and the information signal are synchronized. A combined light emitting procedure for combining and emitting the combined light to the optical transmission path;
In the receiving node among the nodes,
An optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light emission procedure into an electrical signal, and receives an optical beat signal of the combined light; and
The temporal-optical frequency hopping spread code decoding unit determines an optical frequency of the temporal-optical frequency hopping spread code as a frequency difference between the optical frequency of the signal light emitting procedure and the optical frequency of the temporal-optical frequency hopping spread code. By subtracting the optical beat frequency component for each chip time from the optical beat signal received in the optical beat signal reception procedure according to the temporal-optical beat frequency spread code replaced with the optical beat frequency to be A temporal-optical frequency hopping spreading code decoding procedure for decoding the optical beat signal of the signal light encoded by the optical-optical frequency hopping spreading code;
An information signal demodulating unit for demodulating the information signal from an optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding procedure;
An optical frequency hopping code division multiplexing transmission method. An optical frequency hopping code division multiplex transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes,
In the transmitting node among the nodes,
Temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other between nodes are allocated every chip time. When,
A temporal-optical frequency hopping spread code modulator is configured to perform a predetermined time period in the chip time according to the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage procedure. Temporal-optical frequency hopping spread code modulation procedure for outputting an optical frequency hopping signal for changing an optical frequency at each chip time;
The code light emitting unit emits code light of an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spread code by the optical frequency hopping signal in the predetermined time zone, and the chip time In a time zone excluding the predetermined time zone, a code light emission procedure for emitting signal light having a constant optical frequency, and
A signal light emitting unit modulates the signal light emitted in the code light emission procedure on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, A signal light emitting procedure for emitting the code light;
An optical branching procedure in which the optical branching unit splits the signal light and the code light emitted in the signal light outgoing procedure into two, respectively;
The optical delay unit is configured to output the one of the signal light and the code light branched in the optical branching procedure in the predetermined time period so that the timing of emission of the code light coincides with the timing of emission of the signal light. An optical delay procedure for delaying by a time width equal to or greater than the time width and less than the time width of the chip time;
A combined light emitting unit combines the signal light and the code light delayed by the optical delay procedure and the other signal light and the code light branched by the optical branch unit, and the signal light and the code light. A combined light output procedure for outputting combined light, which combines light, to the optical transmission path;
In the receiving node among the nodes,
An optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light emission procedure into an electrical signal, and receives an optical beat signal of the combined light; and
The temporal-optical frequency hopping spread code decoding unit determines the optical frequency of the temporal-optical frequency hopping spread code as a frequency difference between the optical frequency of the signal light and the optical frequency of the temporal-optical frequency hopping spread code. By replacing the optical beat frequency component for each chip time from the optical beat signal received in the optical beat signal reception procedure according to the optical beat frequency spread code replaced with the optical beat frequency A temporal-optical frequency hopping spreading code decoding procedure for decoding the optical beat signal of the signal light encoded by an optical frequency hopping spreading code;
An information signal demodulation unit for demodulating the information signal from an optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding unit;
An optical frequency hopping code division multiplexing transmission method. An optical frequency hopping code division multiplex transmission method in which a plurality of nodes are connected by an optical transmission line, and transmits and receives an information signal between the nodes,
In the transmitting node among the nodes,
Temporal-optical frequency hopping spreading code storage unit for storing temporal-optical frequency hopping spreading code in which optical frequencies orthogonal to each other between nodes are allocated every chip time. When,
A temporal-optical frequency hopping spread code modulator is configured to perform a predetermined time period in the chip time according to the temporal-optical frequency hopping spread code stored in the temporal-optical frequency hopping spread code storage procedure. Temporal-optical frequency hopping spread code modulation procedure for outputting an optical frequency hopping signal for changing an optical frequency at each chip time;
The code light emitting unit emits code light of an optical frequency changed to an optical frequency assigned by the temporal-optical frequency hopping spread code by the optical frequency hopping signal in the predetermined time zone, and the chip time In a time zone excluding the predetermined time zone, a code light emission procedure for emitting signal light having a constant optical frequency, and
A signal light emitting unit modulates the signal light emitted in the code light emission procedure on or off for each block of the temporal-optical frequency hopping spread code according to the information signal, A signal light emitting procedure for emitting the code light to the optical transmission path;
In the receiving node among the nodes,
An optical branching procedure in which the optical branching unit splits the signal light and the code light emitted in the signal light outgoing procedure into two, respectively;
The optical delay unit is configured to output the one of the signal light and the code light branched in the optical branching procedure in the predetermined time period so that the timing of emission of the code light coincides with the timing of emission of the signal light. An optical delay procedure for delaying by a time width equal to or greater than the time width and less than the time width of the chip time;
A combined light emitting unit combines the signal light and the code light delayed by the optical delay procedure and the other signal light and the code light branched by the optical branch unit, and the signal light and the code light. A combined light output procedure for emitting combined light combining light;
An optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light emission procedure into an electrical signal, and receives an optical beat signal of the combined light; and
The temporal-optical frequency hopping spread code decoding unit determines the optical frequency of the temporal-optical frequency hopping spread code as a frequency difference between the optical frequency of the signal light and the optical frequency of the temporal-optical frequency hopping spread code. By replacing the optical beat frequency component for each chip time from the optical beat signal received in the optical beat signal reception procedure according to the optical beat frequency spread code replaced with the optical beat frequency A temporal-optical frequency hopping spreading code decoding procedure for decoding the optical beat signal of the signal light encoded by an optical frequency hopping spreading code;
An information signal demodulation unit for demodulating the information signal from an optical beat signal of the signal light decoded by the temporal-optical frequency hopping spread code decoding unit;
An optical frequency hopping code division multiplexing transmission method. An optical frequency hopping code division multiplexing transmission method further transmitting and receiving an information signal by a plurality of radio base stations connected to the node by the optical transmission path and transmitting and receiving the information signal,
In the radio base station to transmit among the radio base stations,
An optical beat signal receiving unit photoelectrically converts the combined light emitted in the combined light output procedure, and receives an optical beat signal of the combined light; and
A wireless signal transmission unit wirelessly transmitting the optical beat signal received in the optical beat signal reception procedure,
In the radio base station to receive among the radio base stations,
A radio signal receiving procedure for receiving an optical beat signal wirelessly transmitted by the radio signal transmitting procedure by the radio signal receiving unit;
The base station emitting unit adds the frequency of the optical beat signal received in the radio signal receiving procedure to the optical frequency of the signal light emitted in the signal light emitting procedure, and the signal light emitting procedure The base station emission procedure which combines the signal light of the optical frequency of the said signal light radiate | emitted in (8), and radiate | emits the combined light to the said optical transmission line is included. Optical frequency hopping code division multiplexing transmission method.

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