Optical code division multiple access system and signal transmission method thereof

Abstract

The present disclosure relates to the technical field of communications, and provides an optical code division multiple access system and a signal transmission method thereof. The optical code division multiple access system of the present disclosure comprises a signal access control unit, a plurality of data signal input interfaces, an encoder group, an optical channel, a decoder group, a plurality of data signal output interfaces and a signal output control unit; each data signal input interface is equipped with a return-to-zero code optical pulse signal generator; the signal access control unit is configured to determine, in response to a data access request of a user and on the basis of a communication rate required for transmitting a user data signal, whether an idle channel is present, and when an idle channel is present, on the basis of the communication rate required for the user data signal, adjust a repetition period of optical pulses generated by the return-to-zero code optical pulse signal generator.

Description

Optical code division multiple access system and signal transmission method thereof Technical Field

[0001] The present disclosure belongs to the field of communication technology, and particularly relates to an optical code division multiple access system and a signal transmission method thereof. Background Art

[0002] Optical Code Division Multiple Access (OCDMA) is a highly flexible and secure communication technology that applies traditional code division multiple access technology to optical communication systems. OCDMA systems are simple to implement, using passive components for encoding and decoding, without the need for additional synchronization control. This paves the way for their application in scenarios with diverse and agile communication requirements. These scenarios include multimodal rich media transmission and perception, high-speed mobile communications, marine communications, and multi-scale artificial intelligence. Time division multiple access and frequency division multiple access systems, which are currently widely used in optical communications, require high-precision synchronization technology to ensure accurate information transmission, while OCDMA systems have a natural random asynchronous access capability. Random asynchronous access will make service slicing and large-scale heterogeneous network integration for next-generation communications in current 5G communication systems more flexible. Therefore, it is necessary to improve and optimize the asynchronous access capabilities of OCDMA systems to make them more adaptable to new service scenarios and new communication requirements.

[0003] Despite its long history, OCDMA technology continues to demonstrate significant application value in emerging fields. Research has revealed that existing OCDMA systems consume more or more complex codewords, greater power, or wider spectrum resources when transmitting multi-rate signals than single-rate transmission systems. This often requires a complete overhaul of the system's codec architecture, resulting in high upgrade costs and limited flexibility.

[0004] In summary, it is necessary to take measures to transmit as many signals of different rates as possible while making full use of limited codeword resources to meet the current and future needs of random asynchronous access of ultra-fine classified multi-rate services.

[0005] Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a code division multiple access system and a signal transmission method thereof.

[0007] In a first aspect, an embodiment of the present disclosure provides an optical code division multiple access system, comprising: a signal access control unit, multiple data signal input interfaces, an encoder group, an optical channel, a decoder group, multiple data signal output interfaces, and a signal output control unit; wherein the data signal input interface is configured with a return-to-zero code optical pulse signal generator;

[0008] The signal access control unit is configured to respond to a user's data access request and determine whether there is an idle channel based on a communication rate required for transmitting the user data signal, and, if the idle channel exists, adjust the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator based on the communication rate required for transmitting the user data signal;

[0009] The data signal input interface is configured to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group;

[0010] The encoder group includes a plurality of encoders, each of which is configured to encode a received optical pulse signal to generate an encoded optical signal;

[0011] The optical channel is configured to transmit the encoded optical signal to the decoder group;

[0012] The decoder group includes a plurality of decoders, each of which is configured to decode the received encoded optical signal to obtain the user data signal;

[0013] The signal output control unit is configured to control the data signal output interface to output the user data signal decoded by the decoder according to a communication rate required by the user data signal.

[0014] In which, the optical code division multiple access system also includes an electro-optical conversion module and a photoelectric conversion module; when the user data signal is an electrical signal, the electro-optical conversion module is configured to convert the user data signal in the form of an electrical signal into a user data signal in the form of an optical signal, so that the return-to-zero code pulse generator can generate an optical pulse signal based on the user data signal in the form of an optical signal, and then send it to the encoder for encoding; the photoelectric conversion module is configured to convert the decoded user data signal in the form of an optical signal into a user data signal in the form of an electrical signal.

[0015] Wherein, the signal access control unit includes:

[0016] A receiving module configured to receive a data access request from a user;

[0017] a determination module configured to determine, when the receiving module receives the user access request, a communication rate required for a user data signal to be transmitted by the user;

[0018] a query module configured to determine whether there is an idle channel according to the communication rate required by the user data signal;

[0019] The control module is configured to adjust the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator according to the communication rate required by the user data signal when it is determined that there is an idle channel, and control the data signal input interface to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group.

[0020] The receiving module is specifically configured to receive a user's data access request in a query or interrupt manner.

[0021] The query module is specifically configured to determine whether there is an idle channel according to a pre-stored correspondence table of codec links and rates and the communication rate required by the user data signal.

[0022] Wherein, the data signal input interface is an electrical signal interface or an optical signal interface.

[0023] The encoder has a first input interface and a first output interface, the first input interface is correspondingly connected to the data signal input interface, and the first output interface is connected to the optical channel; the first input interface and the first output interface are both optical fiber interfaces.

[0024] The optical channel includes a coupler, an optical fiber and an optical splitter; one end of the coupler is connected to the plurality of encoders, and the other end is connected to one end of the optical splitter through the optical fiber, and the other end of the optical splitter is connected to the plurality of decoders.

[0025] Wherein, the optical channel includes a coupler, a first optical fiber, a first antenna unit, a second antenna unit, a second optical fiber and an optical splitter;

[0026] One end of the coupler is connected to the plurality of encoders, and the other end is connected to the first antenna unit through the first optical fiber. The first antenna unit is connected to the second antenna unit through a spatial channel, and the second antenna unit is connected to one end of the optical splitter through a second optical fiber. The other end of the optical splitter is connected to the plurality of decoders.

[0027] Wherein, the first antenna unit and the second antenna unit are both lens antennas.

[0028] The decoder has a second input interface and a second output interface, the second input interface is connected to the optical channel, and the second output interface is correspondingly connected to the data signal output interface; the second input interface and the second output interface are both optical fiber interfaces.

[0029] Wherein, the signal output control unit includes:

[0030] a detection module configured to detect whether the decoder has the user data signal output and record the serial number of the data signal output interface to output the user data signal;

[0031] a communication rate estimation module configured to process the user data signal output by the decoder, obtain a period of the user data signal, estimate a required communication rate, and mark the estimation result;

[0032] The prompt module is configured to output the serial number of the decoder that outputs the user data signal and the required communication rate, so as to issue a control instruction to the data signal output interface to control whether to output the user data signal.

[0033] The data signal output interface is configured to perform pulse sorting and data judgment on the user data signal output by the decoder.

[0034] Wherein, the signal output by the data signal output interface is a return-to-zero pulse signal.

[0035] The encoder group is a code division multiple access encoder group, and the decoder group is a code division multiple access decoder group; or, the encoder group is a multi-rate encoder group, and the decoder group is a multi-rate decoder group.

[0036] In a second aspect, an embodiment of the present disclosure provides a signal transmission method for an optical code division multiple access system, wherein the optical code division multiple access system adopts any of the optical code division multiple access systems described above, and the method includes:

[0037] The signal access control unit responds to the user's data access request and determines whether there is an idle channel according to the communication rate required for transmitting the user data signal, and when the idle channel exists, adjusts the repetition period of the optical pulse generated by the return-to-zero code optical pulse signal generator according to the communication rate required for the user data signal;

[0038] In response to the signal access control unit determining that there is an idle channel, the data signal input interface outputs the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group; the encoder in the encoder group encodes the received optical pulse signal to generate an encoded optical signal, and transmits the encoded optical signal to the decoder group via the optical channel;

[0039] The decoders in the decoder group decode the received encoded optical signals to obtain the user data signals;

[0040] The signal output control unit controls the data signal output interface to output the user data signal decoded by the decoder according to the communication rate required by the user data signal.

[0041] The signal access control unit responds to the user's data access request and determines whether there is an idle channel according to the communication rate required for transmitting the user data signal, including:

[0042] Receive data access requests from users;

[0043] Upon receiving the user access request, determining a communication rate required for a user data signal to be transmitted by the user;

[0044] determining whether there is an idle channel according to a communication rate required by the user data signal;

[0045] When it is determined that there is an idle channel, the repetition period of the optical pulse generated by the return-to-zero code optical pulse signal generator is adjusted according to the communication rate required by the user data signal, and the data signal input interface is controlled to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group.

[0046] Wherein, when it is determined that there is an idle channel, the step of controlling the data signal input interface to receive the user data signal includes:

[0047] Controlling the return-to-zero pulse generator corresponding to the idle channel to generate a return-to-zero pulse of a specific period matching the communication rate required by the user;

[0048] The data signal input interface is controlled to receive the user data signal.

[0049] The step of receiving a user's data access request includes:

[0050] Receive user data access requests in the form of queries or interruptions.

[0051] The step of the signal output control unit controlling the data signal output interface to output the user data signal obtained by decoding the decoder according to the communication rate required by the user data signal includes:

[0052] detecting whether the decoder outputs the user data signal, and recording the serial number of the decoder that outputs the user data signal;

[0053] processing the user data signal output by the decoder to obtain a period of the user data signal, evaluating a required communication rate, and marking the evaluation result;

[0054] The serial number of the decoder that outputs the user data signal and the required communication rate are output to issue a control instruction to the data signal output interface to control whether to output the user data signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG1 is a block diagram of an optical code division multiple access system according to an embodiment of the present disclosure.

[0056] FIG2 is a timing diagram of a user data signal and an encoded optical signal in scenario 1 of an embodiment of the present disclosure.

[0057] FIG3 is a timing diagram of a user data signal and an encoded optical signal in scenario 2 of an embodiment of the present disclosure.

[0058] FIG4 is a timing diagram of a user data signal and an encoded optical signal in scenario 3 of an embodiment of the present disclosure.

[0059] FIG5 is a timing diagram of a user data signal and an encoded optical signal in scenario 4 of an embodiment of the present disclosure.

[0060] FIG6 is a timing diagram of another user data signal and an encoded optical signal in scenario 2 of an embodiment of the present disclosure.

[0061] FIG7 is a timing diagram of another user data signal and an encoded optical signal in scenario 3 of an embodiment of the present disclosure.

[0062] FIG8 is a block diagram of a signal access control unit according to an embodiment of the present disclosure.

[0063] FIG9 is a block diagram of another optical code division multiple access system according to an embodiment of the present disclosure.

[0064] FIG10 is a schematic diagram of an optical signal according to an embodiment of the present disclosure.

[0065] FIG11 is a schematic diagram of another optical channel according to an embodiment of the present disclosure.

[0066] FIG12 is a block diagram of yet another optical code division multiple access system according to an embodiment of the present disclosure.

[0067] FIG13 is a block diagram of a signal output control unit according to an embodiment of the present disclosure.

[0068] FIG14 is a flowchart of a signal transmission method of an optical code division multiple access system according to an embodiment of the present disclosure.

[0069] FIG15 is a specific flow chart of step S01 of an embodiment of the present disclosure.

[0070] FIG16 is a specific flow chart of step S04 of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0071] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0072] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0073] In the first aspect, Figure 1 is a block diagram of an optical code division multiple access system of an embodiment of the present disclosure; as shown in Figure 1, an embodiment of the present disclosure provides an optical code division multiple access system, which includes a signal access control unit, multiple data signal input interfaces, an encoder group, an optical channel, a decoder group, multiple data signal output interfaces and a signal output control unit; wherein the data signal input interface is configured with a return-to-zero code optical pulse signal generator.

[0074] The signal access control unit is configured to respond to a user's data access request and determine whether there is an idle channel based on the communication rate required for transmitting the user data signal. If an idle channel exists, the signal access control unit adjusts the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator based on the communication rate required for transmitting the user data signal, and allocates a transmission channel.

[0075] The data signal input interface is configured to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group.

[0076] The encoder group includes a plurality of encoders, each of which is configured to encode a received optical pulse signal to generate an encoded optical signal.

[0077] The optical channel is configured to transmit the encoded optical signal to the decoder bank.

[0078] The decoder group includes a plurality of decoders, and the decoders are configured to decode the received encoded optical signals to obtain user data signals.

[0079] The signal output control unit is configured to control the data signal output interface to output the user data signal decoded by the decoder according to the communication rate required by the user data signal.

[0080] In the embodiment of the present disclosure, the signal access control unit can adjust the repetition period of the optical pulse generated by the return-to-zero pulse generator, thereby achieving asynchronous access support for multi-rate user data signals of any proportion. Therefore, the optical code division multiple access system of the embodiment of the present disclosure is more applicable.

[0081] In some examples, the signal access control unit adjusts the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator, and the adjustment may be specifically performed according to the following four situations.

[0082] If the system address code period is fixed to T s The address code chip width, that is, the time width of the light pulse in the encoded optical signal is fixed to T c , which means that multi-rate transmission can be performed without changing the codec of the single-rate transmission system. L = T s / T c is the time domain coding code length, and the data bit time width of user k is T k , that is, the time width of the user data signal of user k is T k .

[0083] Case 1: T k =T s ,As shown in Figure 2, the data bit time width of user k is the same as the system address code period.

[0084] Case 2: T k =n k T s , where n k is a positive integer, that is, n k =1, 2, ..., as shown in FIG3 , the data bit time width of user k is an integer multiple of the system address code period.

[0085] Case 3: T k =(n k +α k )T s , where n k =1, 2, ..., 0 < α k <1, as shown in Figure 4, the data bit time width of user k is greater than the system address code period, but is a non-integer multiple, that is, T k With T s The ratio includes the integer part n k and the fractional part α k , where the integer part n kis a positive integer, the decimal part α k is a positive decimal;

[0086] Case 4: T k =α k T s , where 0<α k <1, as shown in FIG5 , the data bit time width of user k is less than one system address code period, which means that the data of the user cannot be completely optical code division multiple access encoded in the time domain.

[0087] Analyzing cases 1 to 4, we can see that cases 1 to 3 can all be classified into one general form, namely T k =(n k +α k )T s , where n k =1, 2, ..., 0≤α k <1, case 4 remains unchanged. Note that for case 4, α is required here k cannot be equal to 0, if α k A value of 0 means that the signal does not exist.

[0088] For scenario 1, the signal access control unit controls the optical pulse generator to directly convert the user data signal into a pulse with a width of T c The return-to-zero code optical pulse signal is then transmitted to the encoder for encoding, and the return-to-zero code duty cycle is equal to 1 / L.

[0089] For scenario 2, the signal access control unit controls the optical pulse generator to generate a pulse at the data bit time width T of user k. k Converts the user data signal into n k The period is T s , pulse width is T c The return-to-zero code pulse signal is then transmitted to the encoder for encoding, and the return-to-zero code duty cycle is equal to 1 / L;

[0090] For scenario 3, the signal access control unit controls the optical pulse generator to generate a pulse at the data bit time width T of user k. k Converts the user data signal into n k The period is T k / n k , pulse width is T c The return-to-zero code pulse signal is then OCDMA-encoded and transmitted. The return-to-zero code duty cycle is n k T c / T k, the duty cycle is less than 1 / L. The address code chip width remains unchanged, and the codec structure remains unchanged. This method can be understood as processing low-speed data as high-speed data for asynchronous access transmission.

[0091] For scenario 4, for an optical code division multiple access system using one-dimensional time domain coding, since the coding may be incomplete or the coded signals of the two cycles before and after may be mixed together, thus causing interference with the own signal, it is necessary to avoid the transmission of such signals within the system; for an optical code division multiple access system using two-dimensional time-frequency hybrid coding, it is sufficient to ensure that the light wave frequencies of the optical pulse signals within the coding period are different, that is, the light wave wavelengths of the optical pulse signals are different. In this case, the processing method is to ensure that the data bit time width T of user k is different. k The user data signal is converted into a period of T k , pulse width is T c The return-to-zero pulse signal has a duty cycle of T c / T k , the duty cycle is greater than 1 / L.

[0092] The mathematical model of the above situations is summarized. First, consider situations 1 to 3. Assume that the data bit signal transmitted by user k is b k (t), whose value is 0 or 1 changing with time, and the data time period is T k , convert the user's data bit signal into a period of T k / n k , pulse width is T c The return-to-zero code pulse signal of user k is expressed in time domain as follows:

[0093] Where n k =[T k / T s ], that is, take T k / T s The integer part of u(t) represents the unit step function

[0094] Then consider case 4, assuming that the data bit signal transmitted by user k is b k (t), the data time width is T k , convert the user's data into a period of T k , pulse width is T c The return-to-zero code pulse signal of user k converted by the processing method is expressed in time domain as follows:

[0095] In the embodiment of the present disclosure, the encoding process of the encoder and the decoding process of the decoder are as follows:

[0096] Assume that the signal's optical power is P, the number of time-domain coding bits is L, and the code weight—the number of optical pulses within a complete address code period of an optical code division multiple access system—is ω. Without loss of generality, two optical encoding and decoding methods are considered: a one-dimensional time-domain optical encoding and decoding method and a two-dimensional time-frequency hybrid optical encoding and decoding method.

[0097] For the one-dimensional optical encoding and decoding method, the one-dimensional optical encoder c k (j) is a one-dimensional time digital sequence with a value of 0 or 1 and a length of L, δ(t) is a unit impulse function, and the coding output of user k is

[0098] Where, “*” represents the time domain convolution calculation.

[0099] Suppose there are K users, and the delay time for user k (k=0,1,2,...,K-1) to randomly access the system is τ k For simplicity, we add the encoder output signals of K users directly, and the output signal is

[0100] The signal received by the receiver is r(t)=y(t)+n(t) (5)

[0101] Where n(t) is additive white Gaussian noise.

[0102] For decoder m, its decoding sequence is and satisfy

[0103] Then the output of decoder m is

[0104] Substituting equations (4) and (5) into equation (6), we can get

[0105] Especially for case 4, there is

[0106] For the two-dimensional encoding and decoding method, the number of time domain coding bits is L, the code weight is ω, and the encoding sequence of the two-dimensional encoder k is c k (j,λ) represents the two-dimensional coding sequence, λ represents the wavelength of the coded light wave, then the coding output of user k is

[0107] Where “*” represents the time domain convolution sum of the sequence of a specific wavelength.

[0108] Suppose there are K active users, and the delay time for user k (k=0,1,2,...,K-1) to randomly access the system is τ kFor simplicity, we add the encoder output signals of K users directly, and the output signal is

[0109] The signal received by the receiver is r(t,λ)=y(t,λ)+n(t,λ) (10)

[0110] Where n(t,λ) is the additive Gaussian noise.

[0111] For decoder m, its decoding sequence is and satisfy

[0112] The decoder output is

[0113] Substituting equations (9) and (10) into equation (11), we can get

[0114] Especially for case 4, there is

[0115] In some examples, for the above-mentioned cases 2 and 3, the data bit time width T of user k can be k Only one return-to-zero pulse signal is generated in the k Return-to-zero code pulses, as shown in Figures 6 and 7. Based on this, when the above encoder encodes, the data bit time width T of user k is k Only one codeword will be generated within the period T s The optical coding signal, the rest T k -T s The time between is the idle time, during which no optical signal is transmitted. This method can further reduce system power consumption and is a better communication method for green energy conservation.

[0116] In some examples, the main function of the signal access control unit in the embodiment of the present disclosure is to control the access process and signal input. The workflow is as follows: the signal access control unit adopts, including but not limited to, query or interruption methods to receive data access requests from users; after receiving the data access request from the user, the signal access control unit will determine the communication rate required by the user, and then query whether there are available idle channels for the newly accessed user to transmit data. Among them, an idle channel means that there is no signal transmitted on the optical codec link, and the multi-rate signal access control unit matched with the optical codec link meets the communication rate requirements required by the user; if there are available idle channels in the system, the signal access control unit issues an instruction allowing the user to transmit at the requested rate on the corresponding channel, and the user can start to transmit the user data signal at the requested rate to the corresponding channel. At the same time, according to the communication rate required by the user data signal, the repetition period of the optical pulse generated by the return-to-zero code optical pulse signal generator is adjusted. The specific adjustment can still be adjusted according to the above four situations, which will not be repeated here.

[0117] Furthermore, Figure 8 is a block diagram of a signal access control unit according to an embodiment of the present disclosure. As shown in Figure 8 , the signal access control unit, to implement the aforementioned functions, may specifically include a receiving module, a determination module, a query module, and a control module. The receiving module is configured to receive a user's data access request; for example, the receiving module is specifically configured to receive the user's data access request via a query or interrupt. The determination module is configured to, upon receiving the user access request, determine the communication rate required for the user data signal to be transmitted. The query module is configured to determine whether an idle channel exists based on the communication rate required for the user data signal; for example, the query module is specifically configured to determine whether an idle channel exists based on a pre-stored table of codec link and rate correspondences and the communication rate required for the user data signal. The control module is configured to, upon determining the existence of an idle channel, adjust the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator based on the communication rate required for the user data signal, and control the data signal input interface to output the optical pulse signal generated by the return-to-zero code pulse signal generator based on the user data signal to the encoder group.

[0118] In some examples, the function of the data signal input interface in the embodiments of the present disclosure is mainly to provide a hardware interface for user data signals to access the optical code division multiple access system. The data signal input interface can be an electrical signal interface or an optical signal interface, and the interface is configured with a return-to-zero optical pulse signal source required for the system to perform multi-rate signal access control, that is, a return-to-zero code optical pulse signal generator. Among them, for an optical code division multiple access system with K optical coding and decoding links, the data signal input interface of the user data signal input system is K hardware interfaces that do not interfere with each other, and the signal of each input data signal input interface is a serial digital bit signal; the number of return-to-zero code optical pulse signal generators is determined by the number of communication rate values ​​that the system needs to carry, and does not exceed the number of optical coding and decoding links that the system can provide, that is, for an optical code division multiple access system with K optical coding and decoding links, the number of return-to-zero code optical pulse signal generators does not exceed K.

[0119] Furthermore, FIG9 is a block diagram of another optical code division multiple access system according to an embodiment of the present disclosure. As shown in FIG9 , when the data signal input interface in the embodiment of the present disclosure is an electrical signal interface, the embodiment of the present disclosure further includes an electro-optical conversion module and a photoelectric conversion module. The electro-optical conversion module is configured to convert the user data signal from an electrical signal into an optical signal, and then generate an optical pulse signal based on the user data signal in the form of an optical signal through a return-to-zero code pulse generator, which is then sent to the encoder for encoding. The photoelectric conversion module is configured to convert the decoded user data signal in the form of an optical signal into a user data signal in the form of an electrical signal.

[0120] In some examples, the encoder group in the disclosed embodiments encodes multiple user data signals input to the system to generate encoded optical signals. The encoder group comprises multiple parallel encoders, each of which has a first input interface and a first output interface. The first input interface is a fiber interface that receives return-to-zero optical pulse signals generated based on user data bit signals, and the first output interface is a fiber interface that outputs the optical signals encoded by the corresponding encoders.

[0121] In some examples, an optical channel is a transmission channel shared by multiple signals encoded by an encoder group. It can be a wired channel in which multiple encoded optical signals are coupled to a single optical fiber via multiple optical fibers, or it can be a wireless spatial channel in which multiple signals are output via optical fiber-spatial coupling. For example, Figure 10 is a schematic diagram of an optical signal according to an embodiment of the present disclosure. As shown in Figure 10, the optical channel includes a coupler, an optical fiber, and an optical splitter. One end of the coupler is connected to multiple encoders, and the other end is connected to one end of the optical splitter via an optical fiber. The other end of the optical splitter is connected to multiple decoders. For another example, Figure 11 is a schematic diagram of another optical channel according to an embodiment of the present disclosure. As shown in Figure 11, the optical channel includes a coupler, a first optical fiber, a first antenna unit, a second antenna unit, a second optical fiber, and an optical splitter. One end of the coupler is connected to multiple encoders, and the other end is connected to the first antenna unit via the first optical fiber. The first antenna unit is connected to the second antenna unit via a spatial channel, and the second antenna unit is connected to one end of the optical splitter via the second optical fiber. The other end of the optical splitter is connected to multiple decoders. The first antenna unit and the second antenna unit include, but are not limited to, lens antennas.

[0122] In some examples, the decoder group of embodiments of the present disclosure functions to decode received, combined, encoded optical signals to recover the data signals transmitted by the user. The decoder group comprises multiple parallel decoders, each of which has a second input interface and a second output interface. The second input interface is a fiber optic interface that receives the combined, encoded optical signals transmitted via the optical channel, and the second output interface is a fiber optic interface that outputs the optical signal decoded by the corresponding decoder.

[0123] Furthermore, in the embodiment of the present disclosure, the encoder group and the decoder group can not only be an optical code division multiple access (OCDMA) encoder group and a decoder group, Figure 12 is a block diagram of another optical code division multiple access system of the embodiment of the present disclosure; as shown in Figure 12, a multi-rate encoder group and a multi-rate decoder group can also be used.

[0124] In some examples, the signal output control unit in the disclosed embodiments functions to indicate the communication rate of the user data signal output by the decoder group and control the output of the user data signal. The workflow is as follows: first, the signal output control unit detects whether there is a signal output from the output port of the decoder group and records the serial number of the port with a signal output; simultaneously, it uses digital signal processing technology to estimate the period of the output signal of the corresponding port, which is equivalent to the communication rate of the output user data signal, and indicates it; outputs or displays the serial number and rate information of the data signal output port to be outputting the user data signal through an external interface to inform the system administrator or user; and finally, issues a signal output control instruction to the user data signal output interface.

[0125] Furthermore, FIG13 is a block diagram of a signal output control unit of an embodiment of the present disclosure; as shown in FIG13 , the signal output control unit may specifically include a detection module, a communication rate estimation module, and a prompt module to implement the above functions. The detection module is configured to detect whether the decoder has a user data signal output, and record the serial number of the data signal output interface to be used for user data signal output. The communication rate estimation module is configured to process the user data signal output by the decoder, obtain the period of the user data signal, evaluate the required communication rate, and mark the evaluation result. The prompt module is configured to output the serial number of the decoder that outputs the user data signal, and the required communication rate, so as to issue a control instruction to the data signal output interface to control whether the user data signal is output.

[0126] In some examples, the function of the data signal output interface in the embodiment of the present disclosure is to perform pulse shaping and data judgment on the user data signal output by the decoder group, that is, to adjust the waveform of the decoder output signal affected by channel noise to a raised cosine pulse without inter-code interference that is very commonly used in communications, and judge its corresponding data as 0 or 1. It can directly output a return-to-zero code pulse signal, or it can output a non-return-to-zero pulse signal through an optical filter or an electrical filter, and then transmit it to the external interface.

[0127] In a second aspect, FIG14 is a flow chart of a signal transmission method for an optical code division multiple access system according to an embodiment of the present disclosure. As shown in FIG14 , an embodiment of the present disclosure provides a signal transmission method for an optical code division multiple access system, which may be the optical code division multiple access system described above. The signal transmission method for an optical code division multiple access system according to an embodiment of the present disclosure may specifically include the following steps:

[0128] S01. A signal access control unit responds to a user's data access request and determines whether an idle channel exists based on the communication rate required for transmitting the user's data signal. If an idle channel exists, the signal access control unit adjusts the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator based on the communication rate required for transmitting the user's data signal.

[0129] S02. In response to the signal access control unit determining that there is an idle channel, the data signal input interface outputs the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group; the encoder in the encoder group encodes the received optical pulse signal to generate an encoded optical signal, and transmits it to the decoder group through the optical channel.

[0130] S03. The decoders in the decoder group decode the received encoded optical signals to obtain user data signals.

[0131] S04. The signal output control unit controls the data signal output interface to output the user data signal decoded by the decoder according to the communication rate required by the user data signal.

[0132] In the embodiment of the present disclosure, the signal access control unit can adjust the time width of the optical pulse generated by the return-to-zero pulse generator, thereby achieving asynchronous access support for multi-rate user data signals of any proportion. Therefore, the signal transmission method of the optical code division multiple access system of the embodiment of the present disclosure is more applicable.

[0133] In some examples, FIG15 is a specific flow chart of step S01 in an embodiment of the present disclosure; as shown in FIG15 , step S01 may specifically include:

[0134] S011. Receive a data access request from a user in a manner including but not limited to a query or interruption manner.

[0135] In some examples, the receiving module in the signal access control unit may receive a data access request from a user in a manner including but not limited to a query or interruption manner.

[0136] S012. After receiving a data access request from a user, the signal access control unit determines the communication rate required by the user.

[0137] In some examples, when the receiving module receives the user access request, the determination module in the signal access control unit determines the communication rate required for the user data signal to be transmitted by the user.

[0138] S013: Check whether there is an available idle channel for the new user to transmit data.

[0139] The idle channel means that there is no signal transmitted on the optical codec link, and the multi-rate signal access control unit matched with the optical codec link meets the communication rate requirement of the user.

[0140] In some examples, step S013 may specifically be that the query module in the signal access control unit is specifically configured to determine whether there is an idle channel according to a pre-stored correspondence table of codec links and rates and the communication rate required by the user data signal.

[0141] S014. If an available idle channel exists, the signal access control unit issues a command allowing the user to transmit at the requested rate on the corresponding channel. The user then begins transmitting the user data signal at the requested rate on the corresponding channel. Simultaneously, the repetition period of the optical pulses generated by the return-to-zero optical pulse signal generator is adjusted based on the communication rate required by the user data signal.

[0142] In some examples, when the control module in the signal access control unit determines that there is an idle channel, it adjusts the repetition period of the optical pulse generated by the return-to-zero code optical pulse signal generator according to the communication rate required by the user data signal, and controls the data signal input interface to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group.

[0143] In some examples, FIG16 is a specific flow chart of step S04 in an embodiment of the present disclosure; as shown in FIG16 , step S04 may specifically include:

[0144] S041. Detect whether a decoder has the user data signal output, and record the serial number of the decoder that has the user data signal output.

[0145] In some examples, step S041 may detect whether the decoder has a user data signal output by a detection module in the signal access control unit, and record the serial number of the data signal output interface to output the user data signal.

[0146] S042: Process the user data signal output by the decoder to obtain a period of the user data signal, evaluate a required communication rate, and mark the evaluation result.

[0147] In some examples, step S042 can process the user data signal output by the decoder through the communication rate estimation module in the signal access control unit to obtain the period of the user data signal, evaluate the required communication rate, and mark the evaluation result.

[0148] S043: Output the serial number of the decoder that outputs the user data signal and the required communication rate to issue a control instruction to the data signal output interface to control whether to output the user data signal.

[0149] In some examples, step S043 can output the serial number of the decoder that outputs the user data signal and the required communication rate through the prompt module in the signal access control unit to issue a control instruction to the data signal output interface to control whether the user data signal is output.

[0150] In some examples, step S00 may be included before step S01 to initialize the system when the system starts working. In this step, a pre-acquired table of codec links and rates may be stored.

[0151] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An optical code division multiple access system, comprising: A signal access control unit, multiple data signal input interfaces, an encoder group, an optical channel, a decoder group, multiple data signal output interfaces, and a signal output control unit; wherein, the data signal input interface is configured with a return-to-zero optical pulse signal generator. The signal access control unit is configured to respond to a user's data access request, determine whether there is an idle channel according to the communication rate required for transmitting the user data signal, and when there is an idle channel, adjust the repetition period of the optical pulses generated by the return-to-zero optical pulse signal generator according to the communication rate required for the user data signal. The data signal input interface is configured to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group. The encoder group includes multiple encoders, and the encoder is configured to encode the received optical pulse signal to generate an encoded optical signal. The optical channel is configured to transmit the encoded optical signal to the decoder group. The decoder group includes multiple decoders, and the decoder is configured to decode the received encoded optical signal to obtain the user data signal. The signal output control unit is configured to control whether the data signal output interface outputs the user data signal decoded by the decoder according to the communication rate required for the user data signal.

2. The optical code division multiple access system according to claim 1, wherein It further includes an electro-optical conversion module and an opto-electronic conversion module; when the user data signal is an electrical signal, the electro-optical conversion module is configured to convert the user data signal in electrical signal form into a user data signal in optical signal form, so that the return-to-zero code pulse generator generates an optical pulse signal according to the user data signal in optical signal form, and then sends it to the encoder for encoding; the opto-electronic conversion module is configured to convert the user data signal in decoded optical signal form into a user data signal in electrical signal form.

3. The optical code division multiple access system according to claim 1, wherein The signal access control unit includes: A receiving module configured to receive a user's data access request. A judging module configured to judge the communication rate required for the user data signal to be transmitted when the receiving module receives the user access request. A querying module configured to determine whether there is an idle channel according to the communication rate required for the user data signal. A control module configured to, when it is determined that there is an idle channel, adjust the repetition period of the optical pulses generated by the return-to-zero optical pulse signal generator according to the communication rate required for the user data signal, and control the data signal input interface to output the optical pulse signal generated by the return-to-zero pulse signal generator according to the user data signal to the encoder group.

4. The optical code division multiple access system according to claim 3, wherein, The receiving module is specifically configured to receive the user's data access request in a query or interrupt manner.

5. The optical code division multiple access system according to claim 3, wherein, The querying module is specifically configured to determine whether there is an idle channel according to a pre-stored correspondence table of encoding and decoding links and rates and the communication rate required for the user data signal.

6. The optical code division multiple access system according to claim 1, wherein, The data signal input interface is an electrical signal interface or an optical signal interface.

7. The optical code division multiple access system according to claim 1, wherein, The encoder has a first input interface and a first output interface. The first input interface is correspondingly connected to the data signal input interface, and the first output interface is connected to the optical channel. Both the first input interface and the first output interface are optical fiber interfaces.

8. The optical code division multiple access system according to claim 1, wherein The optical channel includes a coupler, an optical fiber, and an optical splitter. One end of the coupler is connected to a plurality of the encoders, and the other end is connected to one end of the optical splitter through the optical fiber. The other end of the optical splitter is connected to a plurality of the decoders.

9. The optical code division multiple access system according to claim 1, wherein, The optical channel includes a coupler, a first optical fiber, a first antenna unit, a second antenna unit, a second optical fiber, and an optical splitter. One end of the coupler is connected to a plurality of the encoders, and the other end is connected to the first antenna unit through the first optical fiber. The first antenna unit is connected to the second antenna unit through a space channel. And the second antenna unit is connected to one end of the optical splitter through the second optical fiber. The other end of the optical splitter is connected to a plurality of the decoders.

10. The optical code division multiple access system according to claim 9, wherein, Both the first antenna unit and the second antenna unit are lens antennas.

11. The optical code division multiple access system according to claim 1, wherein The decoder has a second input interface and a second output interface. The second input interface is connected to the optical channel, and the second output interface is correspondingly connected to the data signal output interface. Both the second input interface and the second output interface are optical fiber interfaces.

12. The optical code division multiple access system according to claim 1, wherein, The signal output control unit includes: A detection module configured to detect whether the decoder has the user data signal output and record the serial number of the data signal output interface for which the user data signal output is to be performed. A communication rate estimation module configured to process the user data signal output by the decoder to obtain the period of the user data signal, evaluate the required communication rate, and mark the evaluation result. A prompt module configured to output the serial number of the decoder that outputs the user data signal and the required communication rate, so as to issue a control instruction to the data signal output interface to control whether to output the user data signal.

13. The optical code division multiple access system according to claim 1, wherein, The data signal output interface is configured to perform pulse shaping and data decision on the user data signal output by the decoder.

14. The optical code division multiple access system according to claim 13, wherein, The signal output by the data signal output interface is a return-to-zero pulse signal.

15. The optical code division multiple access system according to claim 1, wherein, The encoder group is a code division multiple access encoder group, and the decoder group is a code division multiple access decoder group; or, the encoder group is a multi-rate encoder group, and the decoder group is a multi-rate decoder group.

16. A signal transmission method for an optical code division multiple access system, the optical code division multiple access system being the optical code division multiple access system according to any one of claims 1-15, the method including: The signal access control unit responds to the user's data access request, determines whether there is an idle channel according to the communication rate required for transmitting the user data signal, and when there is the idle channel, adjusts the repetition period of the optical pulses generated by the return-to-zero optical pulse signal generator according to the communication rate required for the user data signal. The data signal input interface outputs the optical pulse signal generated by the return-to-zero pulse signal generator based on the user data signal to the encoder group in response to the signal access control unit determining that there is an idle channel; the encoder in the encoder group encodes the received optical pulse signal to generate an encoded optical signal, and transmits it to the decoder group through an optical channel; The decoder in the decoder group decodes the received encoded optical signal to obtain the user data signal; The signal output control unit controls whether the data signal output interface outputs the user data signal decoded by the decoder according to the communication rate required by the user data signal.

17. The signal transmission method of the optical code division multiple access system according to claim 16, wherein, The steps for the signal access control unit to respond to the user's data access request and determine whether there is an idle channel according to the communication rate required for transmitting the user data signal include: Receiving the user's data access request; When receiving the user access request, determining the communication rate required for the user data signal to be transmitted by the user; Determining whether there is an idle channel according to the communication rate required by the user data signal; When it is determined that there is an idle channel, adjusting the repetition period of the optical pulses generated by the return-to-zero code optical pulse signal generator according to the communication rate required by the user data signal, and controlling the data signal input interface to output the optical pulse signal generated by the return-to-zero pulse signal generator based on the user data signal to the encoder group.

18. The signal transmission method of the optical code division multiple access system according to claim 17, wherein, The steps for controlling the data signal input interface to receive the user data signal when it is determined that there is an idle channel include: Controlling the return-to-zero pulse generator corresponding to the idle channel to generate return-to-zero pulses with a specific period matching the communication rate required by the user; Controlling the data signal input interface to receive the user data signal.

19. The signal transmission method of the optical code division multiple access system according to claim 17, wherein, The steps for receiving the user's data access request include: Receiving the user's data access request in a query or interrupt manner.

20. The signal transmission method of an optical code division multiple access system according to claim 16, wherein, The steps for the signal output control unit to control whether the data signal output interface outputs the user data signal decoded by the decoder according to the communication rate required by the user data signal include: Detecting whether the decoder has the user data signal output, and recording the decoder serial number with the user data signal output; Processing the user data signal output by the decoder to obtain the period of the user data signal, evaluating the required communication rate, and marking the evaluation result; Outputting the serial number of the decoder outputting the user data signal and the required communication rate to issue a control instruction to the data signal output interface to control whether to output the user data signal.

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