CN109936393B - Synchronization method and device suitable for extremely low receiving rate - Google Patents
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Abstract
The embodiment of the invention provides a synchronization method and a device suitable for extremely low receiving rate, wherein the method comprises the following steps: comparing each spread spectrum bit in the spread spectrum sequence of the current information bit with each spread spectrum code word sequence after the specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, and determining whether the current information bit is a synchronous position. The synchronization method and the device suitable for the extremely low receiving rate, provided by the embodiment of the invention, can realize rapid and complete synchronization under a short spread spectrum period, and can effectively correct information loss and errors of transmission symbols in a quantum channel, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
Description
Technical Field
The embodiment of the invention relates to the technical field of communication, in particular to a synchronization method and a synchronization device suitable for an extremely low receiving rate.
Background
Quantum communication is an emerging interdisciplinary subject combining quantum physics and classical communication, and carries out information encoding, communication control and safe transmission by taking a quantum state as an information carrier and by means of the basic principle of quantum mechanics. As an important component of quantum communication, quantum secure direct communication technology carries out communication by directly establishing a quantum channel, and both communication parties do not need to determine a secret key in advance in the information transmission process, so that the quantum secure direct communication technology has the advantages of high security, high capacity and the like, and is a novel secure communication technology. However, when the transmitting end loads the transmitted information to the single photon through phase modulation, the single photon carrying the information is directly transmitted through the quantum channel. However, due to the attenuation effect of the quantum channel and the non-ideal characteristic of the single-photon source, the receiving end can only receive a small number of single photons, and the single-photon receiving rate is usually between four parts per million and two parts per thousand. This means that the receiving end can receive only a small amount of transmitted information. And the received sequence is phase shifted due to the effects of time delay and attenuation effects of the channel. If the synchronization method is not adopted to synchronize the code elements, correct decoding information cannot be obtained through de-spreading, so that decoding fails and efficient communication cannot be realized. Therefore, symbol synchronization is a necessary condition for achieving efficient quantum secure direct communication.
In the existing synchronization scheme, the synchronization method adopting a synchronization header and a sliding correlation method is the most common, wherein the synchronization header adopts a section of special sequence, and the received sequence is used for calibration after receiving the section of special code word information; the sliding correlation acquisition method is a time domain serial shift search method, and in the sliding search process, the code rates of the local spread spectrum code and the received signal are different, so that the two codes can be considered to slide relatively at the moment. Firstly, the spread spectrum code generated by a local spread spectrum code generator is used for correlating a received signal, then, the received signal is compared with a threshold value to judge whether the threshold condition is met, the phase state of the spread spectrum code is continuously changed until the threshold value is met, and the phase capturing is completed. Then, the traditional synchronization method cannot realize synchronization because the receiving rate of quantum secure direct communication is too low. Therefore, designing a high-performance and low-implementation-complexity synchronization algorithm suitable for quantum secure direct communication is of great significance for implementing quantum secure direct communication.
Disclosure of Invention
It is an object of embodiments of the present invention to provide a synchronization method and apparatus suitable for very low reception rates that overcomes or at least partially solves the above mentioned problems.
In order to solve the foregoing technical problem, in one aspect, an embodiment of the present invention provides a synchronization method suitable for an extremely low reception rate, including:
comparing each spread spectrum bit in a target spread spectrum sequence with each spread spectrum code word sequence after specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and determining whether the current information bit is a synchronous position or not according to the counting value.
In another aspect, an embodiment of the present invention provides a synchronization apparatus suitable for an extremely low reception rate, including:
the comparison module is used for comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and the synchronization module is used for determining whether the current information bit is a synchronization position according to the count value.
In another aspect, an embodiment of the present invention provides an electronic device, including:
the processor and the memory are communicated with each other through a bus; the memory stores program instructions executable by the processor, which when called by the processor are capable of performing the methods described above.
In yet another aspect, the present invention provides a non-transitory computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the above-mentioned method.
The synchronization method and the device suitable for the extremely low receiving rate, provided by the embodiment of the invention, can realize rapid and complete synchronization under a short spread spectrum period, and enable despread information after synchronization to be basically consistent with information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, information loss and errors of transmission symbols in a quantum channel can be effectively corrected, and the problem of reliable transmission of information in quantum secure direct communication is solved.
Drawings
Fig. 1 is a schematic diagram of a synchronization method suitable for very low reception rate according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a Hadamard codeword base matrix according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating a synchronization apparatus suitable for very low reception rate according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic diagram of a synchronization method applicable to an extremely low reception rate according to an embodiment of the present invention, and as shown in fig. 1, the embodiment of the present invention provides a synchronization method applicable to an extremely low reception rate, where the method includes:
step S101, comparing each spread spectrum bit in a target spread spectrum sequence with each spread spectrum code word sequence after specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and step S102, determining whether the current information bit is a synchronous position according to the counting value.
Specifically, a quantum communication system comprises: the device comprises a sending end, a quantum channel and a receiving end.
At a sending end, a single photon source generates a single photon signal, the single photon signal is subjected to phase coding, a code word sequence generated by the coding is subjected to spread spectrum, a plurality of spread spectrum sequences are generated after the spread spectrum, one information bit corresponds to one spread spectrum sequence, one spread spectrum sequence comprises a plurality of spread spectrum bits, and the number of the spread spectrum bits in one spread spectrum sequence is the spread spectrum period of the code word sequence. And finally, the transmitting end transmits the spread spectrum bits generated by spread spectrum to the receiving end through a quantum channel.
At the receiving end, the spread spectrum bit stream is received, and first, synchronization is performed according to the received spreading sequence.
And when the receiving end is successfully synchronized, despreading and decoding are carried out, so that the information is successfully acquired.
The following description will take a specific codeword space as an example of an r-order Hadamard codeword space after correction. The specific codeword space can be other codeword spaces besides the modified r-order Hadamard codeword space.
When the synchronization starts, firstly, each spread spectrum bit in the target spread spectrum sequence is respectively compared with each spread spectrum code word sequence after the r-order Hadamard code word space spread spectrum is carried out, the number of the same bits is respectively recorded as a group of counting values, and the target spread spectrum sequence is the spread spectrum sequence of the current information bit. The number of the spreading code word sequences in the corrected r-order Hadamard code word space is 2r+1A set of count values comprising 2rAnd counting the value.
Then, it is determined whether the current information bit is a synchronization position based on the count value.
The synchronization method applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that the despread information after synchronization is basically consistent with the information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, and the information loss and errors of transmission symbols in quantum channels can be effectively corrected, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
On the basis of the above-described embodiment, further,
comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after the space spread of the r-order Hadamard code word after the correction specifically comprises:
comparing the 1 st spreading bit in the target spreading sequence with the kth bit of each spreading code word sequence in the corrected r-order Hadamard code word space, comparing the 2 nd spreading bit with the kth +1 th bit of each spreading code word sequence in the corrected r-order Hadamard code word space, and comparing the 3 rd spreading bit with the kth +2 th bit of each spreading code word sequence in the corrected r-order Hadamard code word space until the Nth-kth spreading bit is compared with the Nth bit of each spreading code word sequence in the corrected r-order Hadamard code word space;
wherein, N is the spreading period of the spreading code word.
Specifically, starting from receiving the first spreading bit of the target spreading sequence, comparing the 1 st spreading bit in the target spreading sequence with the kth bit of each spreading code word sequence of the corrected r-order Hadamard code word space, comparing the 2 nd spreading bit with the k +1 th bit of each spreading code word sequence of the corrected r-order Hadamard code word space, comparing the 3 rd spreading bit with the k +2 th bit of each spreading code word sequence of the corrected r-order Hadamard code word space, and repeating until the nth-k spreading bits are compared with the nth bit of each spreading code word sequence of the corrected r-order Hadamard code word space, respectively recording the number of the same bits after comparison is completed, and obtaining 2r+1A count value of individuals, a set of count values.
N is the spreading period of the spreading code word and k is the starting point for the search, i.e., the kth bit of each spreading code word sequence from the modified r-order Hadamard code word space is compared with the 1 st spreading bit in the target spreading sequence.
The synchronization method applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that the despread information after synchronization is basically consistent with the information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, and the information loss and errors of transmission symbols in quantum channels can be effectively corrected, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
On the basis of the foregoing embodiments, further, the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
if judging that one count value in a certain pair of count values is larger than a first threshold value and the other count value is smaller than a second threshold value, determining that the current information bit is a synchronous position and the system enters a synchronous state, wherein the first threshold valueThe number of the spreading code word sequences in the corrected r-order Hadamard code word space is 2 when the number is larger than the second threshold valuer+1The count value is 2 in totalrAnd counting the value.
Specifically, 2r+1Each count value is 2 in totalrAnd for the counting value, the counting value is discussed in stages according to the size of the counting value, if one value of a certain pair of counting values is extremely large and the other value is almost 0, namely, if one value of the certain pair of counting values is larger than a first threshold value and the other value of the certain pair of counting values is smaller than a second threshold value, the current information bit is determined to be a synchronous position, the system enters a synchronous state, wherein the first threshold value is larger than the second threshold value, the first threshold value is extremely large relative to the second threshold value, the second threshold value is almost 0 relative to the first threshold value, and the number of the spreading code word sequences in the modified r-order Hadamard code word space is 2r+1The count value is 2rAnd counting the value.
The synchronization method applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that the despread information after synchronization is basically consistent with the information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, and the information loss and errors of transmission symbols in quantum channels can be effectively corrected, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
On the basis of the foregoing embodiments, further, the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
and if the absolute value of the difference between the two count values in any pair of count values is judged and obtained to be smaller than the third threshold value and is not zero, determining that the current information bit is an asynchronous position, and enabling the system to enter an out-of-step state.
Specifically, the values of each pair of count values are relatively close, that is, the absolute value of the difference between two count values in any pair of count values is smaller than the third threshold value and is not zero, the current information bit is determined to be the asynchronous position, and the system enters the out-of-step state.
The synchronization method applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that the despread information after synchronization is basically consistent with the information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, and the information loss and errors of transmission symbols in quantum channels can be effectively corrected, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
Get 2rAnd for the counting value, determining whether the current information bit is the synchronous position according to the size of each pair of counting values.
The synchronization method applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that the despread information after synchronization is basically consistent with the information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, and the information loss and errors of transmission symbols in quantum channels can be effectively corrected, thereby solving the problem of reliable transmission of information in quantum secure direct communication.
The above method is explained in detail by a specific example as follows:
a cascade code consisting of an LDPC code with the code length of 4000 and the code rate of 0.5 and a 4-order Hadamard code word is adopted as an encoding method. The code word space of the Hadamard code is constructed by a base matrix, fig. 2 is a schematic diagram of the base matrix of the Hadamard code word provided by the embodiment of the invention, as shown in fig. 2, each Hadamard code word is orthogonal, wherein the information bits are [0,20,2 ]1,...,2r-1]And the last bit is a parity bit.
1) At a sending end, generating a single photon signal through a single photon source, carrying out phase coding on the single photon signal, and coding an information sequence into a coding sequence which is connected by a plurality of 16-bit Hadamard code words according to an LDPC and Hadamard cascade mode, wherein the Hadamard code words meet the LDPC check matrix.
2) And (3) spreading each Hadamard code word, wherein the spreading period is 64, the length of a new code word after spreading is 64 x 16, selecting a pseudorandom sequence with the length of 64 x 16, multiplying all code word sequences used for information transmission after spreading by the corresponding position of the pseudorandom sequence to obtain a modified sequence, and the modified sequence has good correlation performance. And passing the corrected code word sequence through a quantum channel.
3) At the receiving end, each received frame is stored, and from the first bit received, each codeword sequence with the length of 64 × 16 selected in sequence is compared with 32 sequences in the code word space after the spread spectrum correction in a state machine by using the correlation of the corrected spread spectrum Hadamard codeword sequences. Starting from the first spread spectrum bit of the received sequence, the spread spectrum bit of each spread spectrum period and the Hadamard sequence after spread spectrum correction respectively judge the state of the current bit according to a set threshold value so as to judge the current state of the system, thereby determining the synchronous position.
4) Starting from a first received sequence with the length of 64 x 16, performing shift comparison by using 32 specific sequences, obtaining 16 pairs of count values for each shift, storing the count values after 64 x 16 shifts, finding out a value meeting a threshold condition for each specific sequence, recording the position of the current shift, then selecting a second received sequence with the length of 64 x 16, finding out the position meeting the condition, and finding out the position with the largest number of occurrences after a plurality of comparisons, wherein the position is a synchronous position.
The Bit Error Rate (BER) of the received information sequence recovered by the receiving end at different signal receiving rates was tested, and the test results are shown in table 1. Under the condition that the receiving rate is more than or equal to 0.004, the error rate of the experimental result is very close to the error rate under the ideal condition, and the synchronous performance can almost reach complete synchronization.
TABLE 1 test results
Fig. 3 is a schematic diagram of a synchronization apparatus suitable for an extremely low reception rate according to an embodiment of the present invention, and as shown in fig. 3, an embodiment of the present invention provides a synchronization apparatus suitable for an extremely low reception rate, for executing the method described in any of the above embodiments, and specifically includes a comparing module 301 and a synchronizing module 302, where:
the comparison module 301 is configured to compare each spread spectrum bit in the target spread spectrum sequence with each spread spectrum codeword sequence after the specific codeword space spreading, and record the number of the same bits as a group of count values, where the target spread spectrum sequence is a spread spectrum sequence of the current information bit; the synchronization module 301 is configured to determine whether the current information bit is a synchronization position according to the count value.
Specifically, a quantum communication system comprises: the device comprises a sending end, a quantum channel and a receiving end.
At a sending end, a single photon source generates a single photon signal, the single photon signal is subjected to phase coding, a code word sequence generated by the coding is subjected to spread spectrum, a plurality of spread spectrum sequences are generated after the spread spectrum, one information bit corresponds to one spread spectrum sequence, one spread spectrum sequence comprises a plurality of spread spectrum bits, and the number of the spread spectrum bits in one spread spectrum sequence is the spread spectrum period of the code word sequence. And finally, the transmitting end transmits the spread spectrum bits generated by spread spectrum to the receiving end through a quantum channel.
And when the receiving end is successfully synchronized, despreading and decoding are carried out, so that the information is successfully acquired.
When the receiving end fails to synchronize successfully according to the current information bit, the receiving end needs to synchronize according to the spread spectrum sequence of the next information bit until the synchronization is successful.
When the synchronization starts, first, each spreading bit in the target spreading sequence is compared with each spreading code word sequence after the specific code word space spreading by the comparison module 301, and the number of the same bits is respectively recorded as a group of count values, where the target spreading sequence is the spreading sequence of the current information bit.
Then, it is determined whether the current information bit is a synchronization position according to the count value through the synchronization module 302.
The synchronization device applicable to the extremely low receiving rate provided by the embodiment of the invention realizes rapid and complete synchronization under a short spreading cycle under the condition of the extremely low receiving rate, and ensures that despread information after synchronization is basically consistent with information under an ideal synchronization condition, so that the whole communication system obtains completely consistent performance with theoretical synchronization, information loss and errors of transmission symbols in quantum channels can be effectively corrected, and the problem of reliable transmission of information in quantum secure direct communication is solved.
Fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, and as shown in fig. 4, the electronic device includes: a processor (processor)401, a memory (memory)402, and a bus 403;
wherein, the processor 401 and the memory 402 complete the communication with each other through the bus 403;
comparing each spread spectrum bit in a target spread spectrum sequence with each spread spectrum code word sequence after specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and determining whether the current information bit is a synchronous position or not according to the counting value.
In addition, the logic instructions in the memory may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Embodiments of the present invention provide a computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions that, when executed by a computer, enable the computer to perform the methods provided by the above-mentioned method embodiments, for example, including:
comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence in a specific code word space, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and determining whether the current information bit is a synchronous position or not according to the counting value.
Embodiments of the present invention provide a non-transitory computer-readable storage medium, which stores computer instructions, where the computer instructions cause the computer to perform the methods provided by the above method embodiments, for example, the methods include:
comparing each spread spectrum bit in a target spread spectrum sequence with each spread spectrum code word sequence after specific code word space spread spectrum, respectively recording the number of the same bits as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
and determining whether the current information bit is a synchronous position or not according to the counting value.
The above-described embodiments of the apparatuses and devices are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (4)
1. A synchronization method for very low reception rates, comprising:
comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after the space spread spectrum of the r-order Hadamard code word after the correction, respectively recording the number of the same bit in each spread spectrum code word sequence as the target spread spectrum sequence as a group of counting values, wherein the target spread spectrum sequence is the spread spectrum sequence of the current information bit;
determining whether the current information bit is a synchronous position according to the count value;
comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after the space spread of the r-order Hadamard code word after the correction specifically comprises:
comparing the 1 st spreading bit in the target spreading sequence with the kth bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words, comparing the 2 nd spreading bit with the kth +1 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words, and comparing the 3 rd spreading bit with the kth +2 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words until the N-k spreading bits are compared with the N-1 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words;
wherein, N is the spread spectrum period of the spread spectrum code word;
the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
if judging that one of a pair of count values is larger than a first threshold value and the other count value is smaller than a second threshold value, determining that the current information bit is a synchronous position, and enabling the system to enter a synchronous state, wherein the first threshold value is larger than the second threshold value, the number of the spreading code word sequences in the corrected r-order Hadamard code word space is S, and the count values totally comprise S/2 pairs of count values;
the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
and if the absolute value of the difference between the two count values in any pair of count values is judged and obtained to be smaller than a third threshold value and not zero, determining that the current information bit is an asynchronous position, and enabling the system to enter a desynchronizing state, wherein the number of the spreading code word sequences in the corrected r-order Hadamard code word space is S, and the count values totally comprise S/2 pairs of count values.
2. A synchronization apparatus adapted for extremely low reception rates, comprising:
the comparison module is used for comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after the space spread spectrum of the r-order Hadamard code word after the correction, respectively recording the number of the same bits in each spread spectrum code word sequence as a group of count values, wherein the target spread spectrum sequence is a spread spectrum sequence of the current information bit;
the synchronization module is used for determining whether the current information bit is a synchronization position according to the count value;
comparing each spread spectrum bit in the target spread spectrum sequence with each spread spectrum code word sequence after the space spread of the r-order Hadamard code word after the correction specifically comprises:
comparing the 1 st spreading bit in the target spreading sequence with the kth bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words, comparing the 2 nd spreading bit with the kth +1 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words, and comparing the 3 rd spreading bit with the kth +2 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words until the N-k spreading bits are compared with the N-1 th bit of each spreading code word sequence after the space spreading of the r-order Hadamard code words;
wherein, N is the spread spectrum period of the spread spectrum code word;
the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
if judging that one of a pair of count values is larger than a first threshold value and the other count value is smaller than a second threshold value, determining that the current information bit is a synchronous position, and enabling the system to enter a synchronous state, wherein the first threshold value is larger than the second threshold value, the number of the spreading code word sequences in the corrected r-order Hadamard code word space is S, and the count values totally comprise S/2 pairs of count values;
the determining, according to the count value, whether the current information bit is a synchronization position specifically includes:
and if the absolute value of the difference between the two count values in any pair of count values is judged and obtained to be smaller than a third threshold value and not zero, determining that the current information bit is an asynchronous position, and enabling the system to enter a desynchronizing state, wherein the number of the spreading code word sequences in the corrected r-order Hadamard code word space is S, and the count values totally comprise S/2 pairs of count values.
3. An electronic device, comprising:
the processor and the memory are communicated with each other through a bus; the memory stores program instructions executable by the processor, the processor invoking the program instructions to perform the method of claim 1.
4. A non-transitory computer-readable storage medium, having stored thereon a computer program, which, when executed by a processor, implements the method of claim 1.
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| CN103152071A (en) * | 2011-12-06 | 2013-06-12 | 福建联拓科技有限公司 | Method and equipment for searching synchronization sequence |
| CN104125053A (en) * | 2014-08-12 | 2014-10-29 | 电子科技大学中山学院 | Method and device for capturing synchronous frame |
| CN105049080A (en) * | 2015-08-25 | 2015-11-11 | 四川九洲电器集团有限责任公司 | Spread spectrum synchronization method and device based on adaptive threshold |
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