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CN111106838B - Communication synchronization method, device and system - Google Patents

Communication synchronization method, device and system Download PDF

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CN111106838B
CN111106838B CN201911406621.9A CN201911406621A CN111106838B CN 111106838 B CN111106838 B CN 111106838B CN 201911406621 A CN201911406621 A CN 201911406621A CN 111106838 B CN111106838 B CN 111106838B
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CN111106838A (en
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屈代明
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Huazhong University of Science and Technology
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/11—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits using multiple parity bits
    • H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
    • H03M13/1105—Decoding

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Abstract

The invention discloses a communication synchronization method, a device and a system, wherein before sending a data signal, an extended synchronization signal carrying parameter information of a demodulated and decoded data signal is sent, based on the extended synchronization signal, a sending end can easily calculate control information of the data signal, the control information does not need to be agreed with the sending end in advance, and different modes of communication can be realized by changing synchronization parameters, so that the flexibility of communication is greatly improved. In addition, the extension synchronous signal does not need to provide information of signal starting time, modulation center frequency and channel phase of a sender, a receiving end receives the extension synchronous signal on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, after demodulation and decoding, the starting time, the modulation center frequency and the channel phase of the extension synchronous signal are determined by checking the validity of a decoding result, a large amount of frequency spectrum resources are saved, and flexible communication can be realized on the premise of ensuring that the channel cost is low.

Description

Communication synchronization method, device and system
Technical Field
The present invention belongs to the field of wireless communication, and more particularly, to a communication synchronization method, apparatus and system.
Background
In order to complete a successful communication, both the sending and receiving sides of the communication need to keep complete synchronization, and with the progress of society and the development of technology, people have higher and higher requirements on communication quality, so that the research on communication synchronization methods, devices and systems has important significance.
In order to keep the sender and the receiver completely synchronized, the receiver needs to know the signal start time, modulation center frequency, channel phase of the sender, and information such as coding, puncturing, interleaving, modulation, spreading/hopping, filtering parameters and the like adopted by the sender. In the existing communication synchronization method, a synchronization signal and a control word are embedded in a communication signal to be transmitted, wherein the synchronization signal provides a signal start time, a modulation center frequency and a channel phase of a transmitter for a receiver; the control word includes necessary parameter information for demodulating and decoding the data codeword, such as modulation mode, coding mode, symbol rate, data length, codeword length, difference between start time of the data codeword and end time of the synchronization codeword, modulation center frequency, and parameter information for puncturing, interleaving, spreading, frequency hopping, filtering, etc. Although the synchronization signal can realize the synchronization of the receiving and transmitting parties, the synchronization signal occupies a large overhead and wastes a large amount of spectrum resources, and in addition, because the synchronization signal is a fixed signal, a listener can easily grasp the ongoing communication behavior of the receiving and transmitting parties by detecting the synchronization signal, so that the confidentiality and the safety of communication are reduced. In addition, since the coding and modulation modes of the data signals at the transmitting end are different, the control words are also different, but in order to save the overhead, in most communication systems, the transmitting and receiving parties usually have good information businesses in advance, so that the flexibility of communication is greatly reduced. As can be seen from the above, the existing communication synchronization method cannot consider both the channel overhead and the flexible communication.
Disclosure of Invention
In view of the above drawbacks or needs for improvement in the prior art, the present invention provides a communication synchronization method, which aims to solve the technical problem in the prior art that both channel overhead and flexible communication cannot be considered due to the fact that a synchronization signal needs to provide signal start time, modulation center frequency, and channel phase information of a sender, and a control word needs to be defined in advance by both the sender and the receiver.
To achieve the above object, in a first aspect, the present invention provides a communication synchronization method, including the following steps:
s1, sending end:
respectively coding the synchronous parameters and the data to obtain synchronous code words and data code words;
modulating the obtained synchronous code words and data code words respectively to form expanded synchronous signals and data signals, and then sequentially sending the expanded synchronous signals and the data signals to a receiving end;
the synchronous parameters comprise parameter information of demodulation and decoding data signals, and the parameter information of the demodulation and decoding data signals carried in the synchronous parameters corresponds to the modulation and coding modes of data one by one;
s2, receiving end:
receiving the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals, respectively decoding the signals, and selecting optimal decoding code words from decoding results;
judging whether the obtained optimal decoding code word is effective, if the optimal decoding code word is effective, the initial time, the modulation center frequency and the channel phase of the current signal are the initial time, the modulation center frequency and the channel phase of the expanded synchronous signal, and extracting the synchronous parameters in the optimal decoding code word;
and calculating the initial time, the modulation center frequency and the channel phase of the subsequent data signal according to the obtained synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization.
Further preferably, the receiving end receives, demodulates and decodes the subsequent data signal according to the obtained synchronization parameter and the calculated start time, modulation center frequency and channel phase of the subsequent data signal, so as to obtain the data sent by the sending end.
Further preferably, the data signal is transmitted immediately after the extended synchronization signal, and the start time of the data signal is equal to the sum of the start time of the extended synchronization signal and the length of the extended synchronization signal.
Further preferably, the modulation center frequency of the data signal is the same as the modulation center frequency of the spread synchronization signal.
Further preferably, the channel phase of the data signal is the same as the channel phase of the extended synchronization signal.
Further preferably, the synchronization parameter further includes a receiver address.
Further preferably, the sending end performs polar code coding on the synchronization parameter;
the method for receiving the expanded synchronous signals by the receiving end on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals and then respectively decoding the demodulated expanded synchronous signals to obtain optimal decoding code words comprises the following steps:
s21, carrying out timing sampling, frequency offset correction and phase correction on the received extended synchronous signal by adopting the combination of a plurality of groups of preset signal start time, modulation center frequency and channel phase, and obtaining P' code receiving sequences after demodulation; wherein, P' is the combination number of the signal starting time, the modulation center frequency and the channel phase, and each code receiving sequence corresponds to a group of parameters including the signal starting time, the modulation center frequency and the channel phase;
s22, decoding each P code word receiving sequences in the P code word receiving sequences simultaneously by adopting a multi-code word receiving sequence SCL decoder to obtain P'/P decoding results;
and S23, selecting the decoding result with the maximum likelihood probability as the optimal decoding code word according to the maximum likelihood principle for the P '/P decoding results, wherein P is a positive integer smaller than P ', and P '/P is an integer.
Further preferably, the method for simultaneously decoding P received sequences of codewords in P' received sequences of codewords by using the multiple received sequences of codewords SCL decoder in step S22 includes the following steps:
s221, receiving sequences for P code words to be decoded
Figure BDA0002348805690000031
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of the preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer;
s222, initializing P paths in the decoder list, and marking the l (l ═ 1, 2., P) path as the l (l ═ 1, 2., P) path
Figure BDA0002348805690000041
Returning to step S221 by setting i to i + 1; wherein S islIndicates that the code word receiving sequence corresponding to the first path in the decoder list is
Figure BDA0002348805690000042
SlThe initial value of (a) is l,
Figure BDA0002348805690000043
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure BDA0002348805690000044
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, noting that the number of current paths in the decoder list is L ', and the L (i ═ 1, 2.., L') th path is L ″
Figure BDA0002348805690000045
Each path is divided into
Figure BDA0002348805690000046
L' is extended to 1,2
Figure BDA0002348805690000047
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure BDA0002348805690000048
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure BDA0002348805690000049
Of decision values, sequence
Figure BDA00023488056900000410
Element (1) of
Figure BDA00023488056900000411
Indicating that the ith path in the decoder list isuiA decision value of (a), and
Figure BDA00023488056900000412
is a known fixed bit uiTaking the value of (A);
s225, sequences in each path
Figure BDA00023488056900000413
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA00023488056900000414
And
Figure BDA00023488056900000415
wherein, L1, 2
Figure BDA00023488056900000416
And
Figure BDA00023488056900000417
all correspond to the receiving sequence
Figure BDA00023488056900000418
And the path
Figure BDA00023488056900000419
And
Figure BDA00023488056900000420
the path metric values are respectively
Figure BDA00023488056900000421
And
Figure BDA00023488056900000422
Figure BDA00023488056900000423
and
Figure BDA00023488056900000424
respectively representing the ith bit channel output of a length N polar code as
Figure BDA00023488056900000425
The transition probabilities of 0 and 1 are input in time;
judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
s226, outputting the corresponding decision sequence on the path with the maximum path metric value from the L paths
Figure BDA0002348805690000051
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
Further preferably, the sending end concatenates CRC codes before the polarization code coding, and performs CRC concatenated polarization code coding on the synchronization parameter; in step S22, the method for simultaneously decoding P codeword received sequences in P' codeword received sequences by using a multiple codeword received sequence SCL decoder includes the following steps:
s221, receiving sequences for P code words to be decoded
Figure BDA0002348805690000052
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of the preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer;
s222, initializing P paths in the decoder list, and marking the l (l ═ 1, 2., P) path as the l (l ═ 1, 2., P) path
Figure BDA0002348805690000053
Returning to step S221 by setting i to i + 1; wherein S islRepresenting a decoder listThe code word receiving sequence corresponding to the first path is
Figure BDA0002348805690000054
SlThe initial value of (a) is l,
Figure BDA0002348805690000055
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure BDA0002348805690000056
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, noting that the number of current paths in the decoder list is L ', and the L (i ═ 1, 2.., L') th path is L ″
Figure BDA0002348805690000057
Each path is divided into
Figure BDA0002348805690000058
L' is extended to 1,2
Figure BDA0002348805690000059
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure BDA00023488056900000510
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure BDA00023488056900000511
Of decision values, sequence
Figure BDA00023488056900000512
Element (1) of
Figure BDA00023488056900000513
Indicating the l-th path in the decoder list at uiA decision value of (a), and
Figure BDA00023488056900000514
is a known fixed bit uiTaking the value of (A);
s225, sequences in each path
Figure BDA00023488056900000515
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA00023488056900000516
And
Figure BDA00023488056900000517
wherein, L1, 2
Figure BDA00023488056900000518
And
Figure BDA0002348805690000061
all correspond to the receiving sequence
Figure BDA0002348805690000062
And the path
Figure BDA0002348805690000063
And
Figure BDA0002348805690000064
the path metric values are respectively
Figure BDA0002348805690000065
And
Figure BDA0002348805690000066
Figure BDA0002348805690000067
and
Figure BDA0002348805690000068
respectively representing the ith bit channel output of a length N polar code as
Figure BDA0002348805690000069
The transition probabilities of 0 and 1 are input in time;
judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
s226, outputting the decision sequence corresponding to the path which meets the CRC check and has the maximum path metric value from the L paths
Figure BDA00023488056900000610
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
Further preferably, the receiving end determines whether the optimal decoding codeword exists and meets CRC check, and if the optimal decoding codeword exists and meets CRC check, the optimal decoding codeword is valid.
Further preferably, the sending end cascades the check code and the polarization code, and checks the synchronous parameter to cascade the polarization code; in step S22, the method for simultaneously decoding P codeword received sequences in P' codeword received sequences by using a multiple codeword received sequence SCL decoder includes the following steps:
s221, receiving sequences for P code words to be decoded
Figure BDA00023488056900000611
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of a preset SCL decoding algorithm, a code receiving sequence is composed of polarization codes, N is the code length of the check cascade polarization codes, and i is a positive integer;
s222, initializing P paths in the decoder list, and marking the l (l ═ 1, 2., P) path as the l (l ═ 1, 2., P) path
Figure BDA00023488056900000612
Returning to step S221 by setting i to i + 1; wherein S islIndicates that the code word receiving sequence corresponding to the first path in the decoder list is
Figure BDA00023488056900000613
SlThe initial value of (a) is l,
Figure BDA00023488056900000614
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure BDA00023488056900000615
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, noting that the number of current paths in the decoder list is L ', and the L (i ═ 1, 2.., L') th path is L ″
Figure BDA0002348805690000071
Each path is divided into
Figure BDA0002348805690000072
L' is extended to 1,2
Figure BDA0002348805690000073
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure BDA0002348805690000074
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure BDA0002348805690000075
Of decision values, sequence
Figure BDA0002348805690000076
Element (1) of
Figure BDA0002348805690000077
Indicating the l-th path in the decoder list at uiA decision value of (a), and
Figure BDA0002348805690000078
is a known fixed bit uiTaking the value of (A);
s225, if uiFor information bits, sequences in each path
Figure BDA0002348805690000079
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA00023488056900000710
And
Figure BDA00023488056900000711
wherein, L1, 2
Figure BDA00023488056900000712
And
Figure BDA00023488056900000713
all correspond to the receiving sequence
Figure BDA00023488056900000714
And the path
Figure BDA00023488056900000715
And
Figure BDA00023488056900000716
the path metric values are respectively
Figure BDA00023488056900000717
And
Figure BDA00023488056900000718
and
Figure BDA00023488056900000719
respectively representing the ith bit channel output of a length N polar code as
Figure BDA00023488056900000720
The transition probabilities of 0 and 1 are input in time; judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
if uiTo check the bits, each path is mapped
Figure BDA00023488056900000721
Is extended to
Figure BDA00023488056900000722
Returning to step S221 by setting i to i + 1; wherein, the sequence
Figure BDA00023488056900000723
Element (1) of
Figure BDA00023488056900000724
Indicating the l-th path in the decoder list at uiAnd wherein
Figure BDA00023488056900000725
Is taken according to uiThe check equation and the result of the information bit judged on the l path in the equation are checked;
s226, outputting the corresponding decision sequence on the path with the maximum path metric value from the L paths
Figure BDA00023488056900000726
Obtaining a decoded codeword, aS recorded on path corresponding to over-decoded codewordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
Further preferably, when the transmitting end performs the polar code encoding on the synchronization parameter, the sequence input into the polar code encoder is enabled
Figure BDA0002348805690000081
Last bit u inNIs a fixed bit; at this time, the method for simultaneously decoding the P codeword received sequences in the P' codeword received sequences by using the multiple codeword received sequence SCL decoder in step S22 includes the following steps:
s221, receiving sequences for P code words to be decoded
Figure BDA0002348805690000082
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index sequence number i of the current decoding bit is greater than 1 and less than or equal to N-1, go to step S223; if the index sequence number i of the current decoding bit is greater than N-1, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of the preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer;
s222, initializing P paths in the decoder list, and marking the l (l ═ 1, 2., P) path as the l (l ═ 1, 2., P) path
Figure BDA0002348805690000083
Returning to step S221 by setting i to i + 1; wherein S islIndicates that the code word receiving sequence corresponding to the first path in the decoder list is
Figure BDA0002348805690000084
SlThe initial value of (a) is l,
Figure BDA0002348805690000085
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure BDA0002348805690000086
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, noting that the number of current paths in the decoder list is L ', and the L (i ═ 1, 2.., L') th path is L ″
Figure BDA0002348805690000087
Each path is divided into
Figure BDA0002348805690000088
L' is extended to 1,2
Figure BDA0002348805690000089
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure BDA00023488056900000810
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure BDA00023488056900000811
Of decision values, sequence
Figure BDA00023488056900000812
Element (1) of
Figure BDA00023488056900000813
Indicating the l-th path in the decoder list at uiA decision value of (a), and
Figure BDA00023488056900000814
is a known fixed bit uiTaking the value of (A);
s225, sequences in each path
Figure BDA00023488056900000815
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA00023488056900000816
And
Figure BDA00023488056900000817
wherein, L1, 2
Figure BDA00023488056900000818
And
Figure BDA00023488056900000819
all correspond to the receiving sequence
Figure BDA00023488056900000820
And the path
Figure BDA00023488056900000821
And
Figure BDA00023488056900000822
the path metric values are respectively
Figure BDA00023488056900000823
And
Figure BDA00023488056900000824
Figure BDA0002348805690000091
and
Figure BDA0002348805690000092
respectively representing the ith bit channel output of a length N polar code as
Figure BDA0002348805690000093
The transition probabilities of 0 and 1 are input in time;
judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
s226, outputting the corresponding decision sequence on the path with the maximum path metric value from the L paths
Figure BDA0002348805690000099
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
Further preferably, the method for determining whether the optimal decoded codeword is valid includes:
mapping the obtained optimal decoding code word into a bipolar sequence to obtain a mapping sequence
Figure BDA0002348805690000094
And calculating a mapping sequence
Figure BDA0002348805690000095
The distance d between the codeword receiving sequences x corresponding to the optimal decoding codewords;
according to the Undetected Error Rate (UER) requirement of the system, the code word receiving sequence x and the mapping sequence corresponding to the optimal decoding code word
Figure BDA0002348805690000096
And judging whether the optimal decoding code word is an effective decoding code word or not by the obtained distance d.
Further preferably, the code word receiving sequence x and the mapping sequence corresponding to the optimal decoding code word are determined according to the UER requirement of the system
Figure BDA0002348805690000097
And the obtained distance d, judge whether the optimum decoding code word is a method of the valid decoding code word, including:
obtaining the number Q of bipolar sequences of which the distance between code word receiving sequences corresponding to the optimal decoding code words in all the bipolar sequences with the length of N is smaller than the distance d; wherein, N is the optimal decoding code word length;
calculating the pre-of the optimal decoding code word according to the obtained bipolar sequence number QUndetected error rate UERe；
If the expected undetectable error rate UEReIf the UER requirement of the communication system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
wherein an undetected error rate is expected
Figure BDA0002348805690000098
And R is the number of redundant bits in the optimal decoding code word.
Further preferably, the code word receiving sequence x and the mapping sequence corresponding to the optimal decoding code word are determined according to the UER requirement of the system
Figure BDA0002348805690000101
And the obtained distance d, judge whether the optimum decoding code word is a method of the valid decoding code word, including:
obtaining the number Q of bipolar sequences of which the distance between code word receiving sequences corresponding to the optimal decoding code words in all bipolar sequences with the length of N is smaller than or equal to the distance d; wherein, N is the optimal decoding code word length;
calculating the expected undetectable error rate UER of the optimal decoding code word according to the obtained bipolar sequence number Qe；
If the expected undetectable error rate UEReIf the UER requirement of the communication system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
wherein an undetected error rate is expected
Figure BDA0002348805690000102
And R is the number of redundant bits in the optimal decoding code word.
In a second aspect, the present invention provides a transmitting module, including a coding unit and a modulation unit;
the coding unit is used for coding the synchronization parameters and the data respectively to obtain synchronization code words and data code words and sending the synchronization code words and the data code words to the modulation unit;
the modulation unit is used for modulating the received synchronous code words and the data code words respectively to form expanded synchronous signals and data signals, and then the expanded synchronous signals and the data signals are sent out in sequence;
the synchronization parameters comprise parameter information of demodulation and decoding data signals, and the parameter information of the demodulation and decoding data signals carried in the synchronization parameters corresponds to the modulation and coding modes of data one to one.
In a third aspect, the present invention provides a receiving module, which includes a demodulating unit, a decoding unit, a judging unit, and a calculating unit;
the demodulation unit is used for receiving and demodulating the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase to obtain synchronous code words and sending the synchronous code words to the decoding unit;
the decoding unit is used for decoding the received synchronous code words, selecting optimal decoding code words from decoding results and sending the optimal decoding code words to the judging unit;
the judging unit is used for judging whether the received optimal decoding code word is effective, if so, the starting time, the modulation center frequency and the channel phase of the current signal are the starting time, the modulation center frequency and the channel phase of the extended synchronous signal, extracting the synchronous parameters in the optimal decoding code word, and sending the synchronous parameters, the starting time, the modulation center frequency and the channel phase of the extended synchronous signal to the calculating unit;
the calculation unit is used for calculating the initial time, the modulation center frequency and the channel phase of the subsequent data signal according to the received synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization.
In a fourth aspect, the present invention provides a communication synchronization system, including the transmitting module proposed in the second aspect of the present invention and the receiving module proposed in the third aspect of the present invention; the transmitting module transmits the signal to the receiving module.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
1. the invention provides a communication synchronization method, which is characterized in that an extended synchronization signal is transmitted before a data signal is transmitted. The extended synchronization signal carries parameter information of demodulation and decoding data signals, and the carried parameter information of the demodulation and decoding data signals corresponds to the modulation and coding modes of data one to one, so that based on the extended synchronization signal, a sending end can easily calculate control information of the data signals, the control information does not need to be agreed with the sending end in advance, communication in different modes can be realized by changing synchronization parameters, and the flexibility of communication is greatly improved. In addition, the invention does not need to provide the signal starting time, the modulation center frequency and the channel phase of the sending end for the receiving end in addition in the expanded synchronous signal, the receiving end receives the expanded synchronous signal on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, after demodulating and decoding the expanded synchronous signal, and further checks the validity of the obtained decoding result to determine whether the current combination corresponds to the starting time, the modulation center frequency and the channel phase of the expanded synchronous signal, thereby further calculating the starting time, the modulation center frequency and the channel phase of the subsequent data signal, realizing the communication synchronization of the receiving end and the sending end, greatly reducing the occupation of the expenditure and saving a large amount of spectrum resources. Therefore, the method provided by the invention can realize flexible communication on the premise of ensuring that the channel overhead is small.
2. In the communication synchronization method provided by the invention, the expanded synchronization signal is a non-fixed signal, and the synchronization parameter in the expanded synchronization signal changes along with the change of the communication mode, so that a listener cannot grasp the forward communication behavior of transmitting and receiving double-transmitter by detecting the synchronization signal, and the confidentiality and the safety are higher.
3. The communication synchronization method provided by the invention avoids the dependence on error detection codes by checking the effectiveness of the obtained decoding result, can reduce the resource overhead of transmitting error detection bits, thereby effectively improving the coding efficiency and the error correction performance, eliminating the limitation of the number of the error detection bits on the control capability of the UER, and flexibly realizing the control on the undetectable error rate of decoding according to the actual requirements of the UER of the system.
Drawings
FIG. 1 is a flow chart of a communication synchronization method provided by the present invention;
fig. 2 is a schematic diagram of a transmitting end transmitting signals provided by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
To achieve the above object, in a first aspect, the present invention provides a communication synchronization method, as shown in fig. 1, including the following steps:
s1, sending end:
respectively coding the synchronous parameters and the data to obtain synchronous code words and data code words;
modulating the obtained synchronous code words and data code words respectively to form expanded synchronous signals and data signals, and then sequentially sending the expanded synchronous signals and the data signals to a receiving end;
the synchronization parameters include parameter information of demodulated and decoded data signals, such as parameter information of modulation mode, coding mode, symbol rate, data length, code word length, difference between start time of data code word and end time of synchronization code word, modulation center frequency, and puncturing, interleaving, spreading, frequency hopping, filtering, etc.; the parameter information of the demodulated and decoded data signals carried in the synchronization parameters corresponds to the modulation and coding modes of the data one to one. Preferably, the synchronization parameter further comprises a receiver address.
Specifically, the method at the transmitting end may use methods such as polarization code encoding and check-cascade polarization code encoding to encode the synchronization parameter. In an alternative embodiment 1, the transmitting end performs polar code encoding on the synchronization parameters. The synchronization parameter includes 16 information bits, wherein 8 bits are the address of the receiving party, and the other 8 bits are parameter information for demodulating and decoding the data signal, specifically including the modulation mode of the data code word, the coding mode of the data, the symbol rate, and the data length. The modulation mode of the data codeword occupies 2 bits, and the value is 01 in this embodiment, which means that QPSK is used to modulate the data codeword. The encoding mode of the data occupies 1 bit, and the value is 1 in the embodiment, which means that the data is encoded by using the LDPC; the symbol rate occupies 2 bits, and the value is 01 in the embodiment, which means that the symbol rate is 2 MHz; the data length occupies 3 bits, and in this embodiment, the value is 100, which indicates that the data length is 1024 bits. And carrying out polarization code coding on the synchronization parameters to obtain 64 coded bits, modulating the obtained synchronization code words by adopting BPSK (binary phase shift keying), modulating the symbol rate to 500MHz central frequency at 1MHz, and sending to a receiving end.
The data signal can be sent immediately after the extended synchronous signal, or the extended synchronous signal can be sent at intervals, when the extended synchronous information is sent after the interval is a period, the interval time is added into the synchronous parameters, so that the sending end can calculate the initial time of the data signal, and the communication is flexible. Specifically, the start time of the data signal is the sum of the start time of the extended synchronization signal, the interval time and the length of the extended synchronization signal. Preferably, the data signal is transmitted next to the extended sync signal, and the start time of the data signal is equal to the sum of the start time of the extended sync signal and the length of the extended sync signal.
In this embodiment, after the extended synchronization signal is transmitted, the data signal is transmitted, as shown in fig. 2. The modulation and coding modes of the data correspond to the parameter information of the demodulated and decoded data signals carried in the synchronization parameters one to one. Specifically, the sending end performs LDPC encoding on data to be sent, where the length of a codeword is 1024 encoded bits, and then modulates a data codeword by using QPSK. The start time of the data signal is the start time of the extended synchronization signal plus the transmission time of 64 BPSK symbols.
The modulation center frequency, channel phase and symbol rate of the data signal and the extended synchronization signal can be the same or different, and when the modulation center frequency, channel phase and symbol rate are different, the difference between the two needs to be correspondingly added into the synchronization parameters, so that the sending end can conveniently calculate the corresponding information of the corresponding data signal, and the communication is flexible. In this embodiment, the modulation center frequency and the channel phase of the data signal are the same as those of the spread synchronization signal, the symbol rate is 1MHz, and the data signal is modulated on the center frequency of 500MHz to be transmitted.
Through the mode, the sending end can easily calculate the control information of the data signal according to the received extended synchronous signal, does not need to agree with the sending end in advance, and can realize communication in different modes by changing the synchronous parameters, so that the flexibility of communication is greatly improved. In addition, the extended synchronous signal provided by the invention is a non-fixed signal, and the synchronous parameter in the extended synchronous signal changes along with the change of the communication mode, so that a listener cannot grasp the forward communication behavior of transmitting and receiving double-transmitting by detecting the synchronous signal, and the confidentiality and the safety are high.
The synchronization parameters include any of the above-mentioned modulation scheme of the data codeword, coding scheme of the data, symbol rate, data length, difference between the start time of the data signal and the end time of the spread synchronization signal, and difference between the modulation center frequency, channel phase, and symbol rate of the data signal and the spread synchronization signal, and necessary parameters for demodulating and decoding the data signal, such as puncturing, interleaving, spreading, frequency hopping, and filtering, according to the specific communication scheme of the transmitting and receiving terminals.
S2, receiving end:
receiving the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals, respectively decoding the signals, and selecting optimal decoding code words from decoding results; specifically, in an optional manner, for the obtained decoding result, the decoding result with the maximum likelihood probability is selected from the obtained decoding results according to the maximum likelihood principle, and is used as the optimal decoding codeword;
judging whether the obtained optimal decoding code word is effective, if the optimal decoding code word is effective, the initial time, the modulation center frequency and the channel phase of the current signal are the initial time, the modulation center frequency and the channel phase of the expanded synchronous signal, and extracting the synchronous parameters in the optimal decoding code word; in addition, in an alternative embodiment, if the optimal decoded codeword is invalid, the process goes to step S1, and the sender retransmits the signal.
And calculating the initial time, the modulation center frequency and the channel phase of the subsequent data signal according to the obtained synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization. Specifically, when the data signal is not sent immediately following the extended synchronization signal, or the modulation center frequency or the channel phase of the data signal and the extended synchronization signal are different, the start time, the modulation center frequency and the channel phase of the obtained extended synchronization signal are respectively added to the difference values of the corresponding parameters in the synchronization parameters when the synchronization parameters correspondingly include the difference values of the corresponding parameters, so that the corresponding information of the corresponding data signal can be conveniently calculated, and the communication synchronization of the receiving party and the transmitting party is realized.
Preferably, the sending end performs polar code encoding on the synchronization parameter; specifically, when the synchronous parameters are encoded by the polarization code, the input sequence of the polarization code encoder is
Figure BDA0002348805690000151
Bit u1To uNSequentially transmitting on the 1 st to the Nth bit channels, and the polar code non-fixed bit channel sequence number set is
Figure BDA0002348805690000153
M is a positive integer, and the fixed bit channel sequence number set is marked as Ac. The elements in the set A satisfy a when i is more than 1 and less than j and less than Mi＜aj. The non-fixed bit sequence is denoted as
Figure BDA0002348805690000154
The fixed bits of the polarization code are known at both the transmitting and receiving ends, the fixed bit sequence
Figure BDA0002348805690000155
Set to all 0 s. The polarization code is coded into
Figure BDA0002348805690000152
GNA matrix is generated for the polarization code.
The method for receiving the expanded synchronous signals by the receiving end on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals and then respectively decoding the demodulated expanded synchronous signals to obtain optimal decoding code words comprises the following steps:
s21, carrying out timing sampling, frequency offset correction and phase correction on the received extended synchronous signal by adopting the combination of a plurality of groups of preset signal start time, modulation center frequency and channel phase, and obtaining P' code receiving sequences after demodulation; wherein, P' is the combination number of the signal starting time, the modulation center frequency and the channel phase, and each code receiving sequence corresponds to a group of parameters including the signal starting time, the modulation center frequency and the channel phase;
specifically, M is set for the signal start time1Seed value, setting M for modulation center frequency2Seed value, setting M for channel phase3The seed value is total of P' ═ M1M2M3And (3) carrying out value combination, namely, for each value combination, sampling a received signal at fixed time according to the signal starting time in the value combination, carrying out frequency offset correction according to the modulation center frequency in the value combination, carrying out phase correction according to the channel phase in the value combination to obtain a corrected signal sequence, and then obtaining a code word receiving sequence through demodulation, and recording the code word receiving sequence as a corrected signal sequence
Figure BDA0002348805690000161
Wherein l is 1,2, P', M1、M2、M3Are all positive integers. It should be noted that the number of combinations of signal start time, modulation center frequency and channel phase is large enough to cover the possible start time, modulation center frequency and channel phase.
In an alternative embodiment 2, first, M is set for the signal start time14 values are obtained; setting for modulation center frequencyM24 values are recorded as f1，f2，f3，f4(ii) a Setting M for channel phase3The values are 4 and are respectively marked as theta1，θ2，θ3，θ4. Sampling the received signal at fixed time according to a preset signal starting time, wherein the length of each sampling signal is Np110, 4 sampling output signals can be obtained
Figure BDA0002348805690000162
And the initial sampling points of the 4 output signals are sequentially marked as r1，r2，r3，r4Since the sampling rate is 8 times of the symbol rate, the receiving end needs to perform 8 times of down sampling, so
Figure BDA0002348805690000163
Wherein l is ∈ [1,4 ]]，wi＝r(i-1)×8+l. Sampling the obtained 4 channels to output signal
Figure BDA0002348805690000164
Separately performing frequency offset correction, wherein each output signal is
Figure BDA0002348805690000165
l∈[1,4]Are separately carried out1，f2，f3，f4And correcting the four frequency deviations, and outputting 16 paths of signals in total. Respectively carrying out 4 phase offset corrections on the output 16 paths of signals, and outputting M in total1M2M364 signals. Then, for the 64 paths of signals output
Figure BDA0002348805690000166
Each path of signals is subjected to zero filling operation, the length of the signals after zero filling is 128 of the mother code of the sending end, and 64 paths of signals after zero filling are output and recorded as
Figure BDA0002348805690000167
Will signal
Figure BDA0002348805690000168
And demodulating by adopting a BPSK algorithm to obtain 64 code word receiving sequences.
S22, decoding each P code word receiving sequences in the P code word receiving sequences simultaneously by adopting a multi-code word receiving sequence SCL decoder to obtain P'/P decoding results and corresponding code word receiving sequences; and for the P '/P decoding results, selecting the decoding result with the maximum likelihood probability as the optimal decoding code word according to the maximum likelihood principle, wherein P is a positive integer smaller than P ', and P '/P is an integer.
Specifically, in an optional embodiment 3, P' is 64, P is 8, and L is 8. In step S22, the method for simultaneously decoding P codeword received sequences in P' codeword received sequences by using a multiple codeword received sequence SCL decoder includes the following steps:
s221, receiving sequences for P code words to be decoded
Figure BDA0002348805690000171
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of the preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer;
s222, initializing P paths in the decoder list, and marking the l (l ═ 1, 2., P) path as the l (l ═ 1, 2., P) path
Figure BDA0002348805690000172
Returning to step S221 by setting i to i + 1; wherein S islIndicates that the code word receiving sequence corresponding to the first path in the decoder list is
Figure BDA0002348805690000173
SlThe initial value of (a) is l,
Figure BDA0002348805690000174
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure BDA0002348805690000175
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, noting that the number of current paths in the decoder list is L ', and the L (i ═ 1, 2.., L') th path is L ″
Figure BDA0002348805690000176
Each path is divided into
Figure BDA0002348805690000177
L' is extended to 1,2
Figure BDA0002348805690000178
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure BDA0002348805690000179
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure BDA00023488056900001710
Of decision values, sequence
Figure BDA00023488056900001711
Element (1) of
Figure BDA00023488056900001712
Indicating the l-th path in the decoder list at uiA decision value of (a), and
Figure BDA00023488056900001713
is a known fixed bit uiTaking the value of (A);
s225, sequences in each path
Figure BDA00023488056900001714
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA0002348805690000181
And
Figure BDA0002348805690000182
wherein, L1, 2
Figure BDA0002348805690000183
And
Figure BDA0002348805690000184
all correspond to the receiving sequence
Figure BDA0002348805690000185
And the path
Figure BDA0002348805690000186
And
Figure BDA0002348805690000187
the path metric values are respectively
Figure BDA0002348805690000188
And
Figure BDA0002348805690000189
Figure BDA00023488056900001810
and
Figure BDA00023488056900001811
respectively representing the ith bit channel output of a length N polar code as
Figure BDA00023488056900001812
The time inputs are respectively0. 1, transition probability;
judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
s226, outputting the corresponding decision sequence on the path with the maximum path metric value from the L paths
Figure BDA00023488056900001813
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
In an optional embodiment 4, the sending end may further perform CRC concatenated coding before the polar code coding, and perform CRC concatenated polar code coding on the synchronization parameter; at this time, compared with the method described in alternative embodiment 3, the method described in step S22 modifies step S226 described in alternative embodiment 3 to: outputting a decision sequence corresponding to the path satisfying the CRC check and having the maximum path metric value from the L paths
Figure BDA00023488056900001814
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word. At this time, the receiving end judges whether the optimal decoding code word exists and meets the CRC check, and if the optimal decoding code word exists and meets the CRC check, the optimal decoding code word is valid.
In an optional embodiment 5, the sending end concatenates the Check code with the polarization code, and checks the Concatenated polarization code for the synchronization parameter, specifically, concatenates the Check code with the polarization code, which may significantly improve the error correction performance of the polarization code, and the Concatenated code is referred to as the Check Concatenated polarization code, wherein the basic principle of checking the Concatenated polarization code is described in articles Tao Wang, Daiming Qu, and Tao Jiang, "Parity-Check-coordinated Polar Codes," IEEE Communications Letters, vol.20, No.12, pp.2342-2345, and dec.2016; in the check equation for checking the outer code of the concatenated polar code, the selection method of the information bit and the check bit is disclosed in the patent of 'a method for error correction coding of concatenated polar code and multi-bit parity check code' (patent number: CN201510995761. X). At this time, the method for simultaneously decoding the P received code sequences in the P' received code sequences by using the multiple received code sequence SCL decoder in step S22 is different from the method described in alternative embodiment 3 in that:
step S221 is modified to: receiving sequences for P code words to be decoded
Figure BDA0002348805690000191
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of a preset SCL decoding algorithm, a code receiving sequence is composed of polarization codes, N is the code length of the check cascade polarization codes, and i is a positive integer;
step S225 is modified to: if uiFor information bits, sequences in each path
Figure BDA0002348805690000192
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure BDA0002348805690000193
And
Figure BDA0002348805690000194
wherein, L1, 2
Figure BDA0002348805690000195
And
Figure BDA0002348805690000196
all correspond to the receiving sequence
Figure BDA0002348805690000197
And the path
Figure BDA0002348805690000198
And
Figure BDA0002348805690000199
the path metric values are respectively
Figure BDA00023488056900001910
And
Figure BDA00023488056900001911
and
Figure BDA00023488056900001912
respectively representing the ith bit channel output of a length N polar code as
Figure BDA00023488056900001913
The transition probabilities of 0 and 1 are input in time; judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
if uiTo check the bits, each path is mapped
Figure BDA00023488056900001914
Is extended to
Figure BDA00023488056900001915
Returning to step S221 by setting i to i + 1; wherein, the sequence
Figure BDA00023488056900001916
Element (1) of
Figure BDA00023488056900001917
Indicating the l-th path in the decoder list at uiAnd wherein
Figure BDA00023488056900001918
Is taken according to uiAnd checking the check equation and the judged result of the information bit on the ith path in the equation to obtain the check result.
In one optionIn the embodiment 6, when the transmitting end performs the polar code encoding on the synchronization parameter, the sequence inputted to the polar code encoder is used
Figure BDA00023488056900001919
Last bit u inNIs a fixed bit; at this time, the method for simultaneously decoding the P received code sequences in the P' received code sequences by using the multiple received code sequence SCL decoder in step S22 is different from the method described in alternative embodiment 3 in that:
step S221 is modified to: receiving sequences for P code words to be decoded
Figure BDA0002348805690000201
If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index sequence number i of the current decoding bit is greater than 1 and less than or equal to N-1, go to step S223; if the index sequence number i of the current decoding bit is greater than N-1, go to step S226; and P is less than or equal to L, L is the maximum path number of a preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer. By making the input sequence of a polar code encoder
Figure BDA0002348805690000202
Last bit u ofNIs a fixed bit and skips the last bit u in the decoding processNThe value of the carrier phase is only required to be between 0 and pi, so that half of decoding can be reduced, and the decoding efficiency is greatly improved.
It should be noted that the polar code is a linear block code whose coding formula is
Figure BDA0002348805690000203
Wherein N represents the length of the code of the polarization code, vector
Figure BDA0002348805690000204
Representing polar code words, ci(i ═ 1, 2.. times.n) denotes the ith coded bit, the vector
Figure BDA0002348805690000205
From two sub-vectors uA＝(uiI ∈ A) and
Figure BDA0002348805690000206
composition, set
Figure BDA0002348805690000207
Non-fixed set of bit indices, called polar codes
Figure BDA00023488056900002010
The complement of a is called the fixed set of bit indices of the polar code. When the polarization code is coded, the sub-vector uASet as information bit sequence, sub-vector
Figure BDA00023488056900002011
The fixed bit sequence known to the receiving end is set to be a sequence of all 0's. According to uAAnd
Figure BDA00023488056900002012
determining a vector
Figure BDA0002348805690000208
And coding to obtain polarization code word
Figure BDA0002348805690000209
By the method, the signal start time, the modulation center frequency and the channel phase of the sending end do not need to be additionally provided for the receiving end in the expanded synchronous signal, the receiving end receives the expanded synchronous signal on a plurality of groups of preset combinations of the signal start time, the modulation center frequency and the channel phase, decodes the obtained synchronous code word after demodulation, and further verifies the validity of the obtained decoding result to determine whether the current combination corresponds to the start time, the modulation center frequency and the channel phase of the expanded synchronous signal, so that the start time, the modulation center frequency and the channel phase of the subsequent data signal are further calculated, the communication synchronization of the receiving end and the sending end is realized, the occupation of overhead is greatly reduced, and a large amount of frequency spectrum resources are saved.
Preferably, the method for determining whether the optimal decoded codeword is valid includes:
mapping the obtained optimal decoding code word into a bipolar sequence to obtain a mapping sequence
Figure BDA0002348805690000211
And calculating a mapping sequence
Figure BDA0002348805690000212
The distance d between the codeword receiving sequences x corresponding to the optimal decoding codewords; specifically, the optimal decoding codeword is a 0, 1 sequence with length N, and under the condition of correct decoding, the decoding codeword is the same as the encoding codeword. Mapping the optimal decoding code word into a bipolar sequence to obtain a mapping sequence
Figure BDA0002348805690000213
Wherein, in an alternative embodiment 7, bit 0 in the decoded codeword is mapped to +1, and bit 1 in the decoded codeword is mapped to-1; mapping sequences
Figure BDA0002348805690000214
The distance between the received sequences x of code words corresponding to the optimal decoded code words is specifically Euclidean distance, and the distance
Figure BDA0002348805690000215
According to UER requirement of system, receiving sequence x and mapping sequence of code word corresponding to optimum decoding code word
Figure BDA0002348805690000216
And judging whether the optimal decoding code word is an effective decoding code word or not by the obtained distance d.
In an optional embodiment, according to the UER requirement of the system, the code word receiving sequence x and the mapping sequence corresponding to the optimal decoding code word
Figure BDA0002348805690000217
And the obtained distance d, judge whether the optimum decoding code word is a method of the valid decoding code word, including:
1) obtaining the number Q of bipolar sequences of which the distance between code word receiving sequences x corresponding to the optimal decoding code words in all bipolar sequences with the length of N is smaller than the distance d;
in this embodiment, values of elements in the bipolar sequence are all +1 or-1; in all bipolar sequences
Figure BDA0002348805690000218
In, calculate satisfied with
Figure BDA0002348805690000219
The number of bipolar sequences Q. By analyzing the above formula, record
Figure BDA00023488056900002110
The above problem can be effectively translated into a bipolar sequence of the received sequence x for the code word corresponding to the closest optimal decoded code word among all bipolar sequences of length N
Figure BDA00023488056900002111
Is calculated to satisfy
Figure BDA00023488056900002112
Due to the number of bipolar sequences
Figure BDA00023488056900002113
The above problem can be further translated into, in all bipolar sequences
Figure BDA0002348805690000221
In, calculate satisfied with
Figure BDA0002348805690000222
The number of bipolar sequences of (a); and can be further converted to, in all bipolar sequences
Figure BDA0002348805690000223
In, calculate satisfied with
Figure BDA0002348805690000224
The number Q of bipolar sequences of (2), wherein,
Figure BDA0002348805690000225
representing a sequence
Figure BDA0002348805690000226
And
Figure BDA0002348805690000227
a set of sequence numbers of non-identical elements,
Figure BDA0002348805690000228
representing bipolar sequences
Figure BDA0002348805690000229
And bipolar sequences
Figure BDA00023488056900002210
A set of sequence numbers of non-identical elements. Due to the fact that
Figure BDA00023488056900002211
Is a constant number, memory
Figure BDA00023488056900002212
Solving the problem of the number Q is further convertible to
Figure BDA00023488056900002213
In, calculate satisfied with
Figure BDA00023488056900002214
The number of bipolar sequences of (a); in summary, the problem of the final solution number Q may be converted to a calculation satisfying the requirement in the subset S of the sequence numbers a ═ {1,2, …, N } of all the elements in the sequence x
Figure BDA00023488056900002215
Wherein the subset S includes an empty set and a full set.
Based on the above inference, in the embodiment of the present invention, obtaining the number Q of bipolar sequences whose distance from the sequence x is smaller than the distance d in all bipolar sequences with the length N specifically includes:
1.1) obtaining a code word receiving sequence x ═ x corresponding to the optimal decoding code word in all bipolar sequences with the length of N1,x2,…,xN]Bipolar sequence of (2)
Figure BDA00023488056900002216
In particular, bipolar sequences
Figure BDA00023488056900002217
Of (2) element(s)
Figure BDA00023488056900002218
The acquisition mode is as follows: if xgIs not less than 0, then
Figure BDA00023488056900002219
If not, then,
Figure BDA00023488056900002220
where g ∈ {1,2, …, N }.
1.2) introduction of Bipolar sequences
Figure BDA00023488056900002221
And mapping sequences
Figure BDA00023488056900002222
Comparing to obtain the serial number sets of elements which are not identical in the two sequences
Figure BDA00023488056900002223
1.3) aggregation according to sequence number
Figure BDA00023488056900002224
Screening out corresponding elements from the sequence x, and calculating the sum of absolute values of the screened elements to obtain a constant
Figure BDA00023488056900002225
1.4) obtain the sequence number set a of all elements in sequence x ═ {1,2, …, N }, and satisfy all subsets of sequence number set a
Figure BDA00023488056900002226
Number of subsets Q*Determining the number Q of bipolar sequences with the distance between the bipolar sequences with the length N and the sequence x smaller than the distance d; wherein S is a subset of the sequence number set A;
specifically, the number of subsets Q*The acquisition method specifically comprises the following steps: for the interval [0, C]Performing M equal division to obtain M +2 subintervals in a real number range; for each subset S 'with the number of elements n and contained in the sequence set A, screening the elements from the sequence x according to the subset S', and calculating the sum of absolute values of the screened elements
Figure BDA0002348805690000231
Marking as the screening sum of the subset S'; counting the screening of the subsets and the distribution condition among the subintervals to obtain a distribution sequence Bn＝[Bn,0,Bn,1,…,Bn,M+1](ii) a According to distribution sequence BnCalculating the number of subsets Q*Comprises the following steps:
Figure BDA0002348805690000232
wherein N belongs to {1,2, …, N }; and distribution sequence BnThe acquisition mode is specifically as follows: taking absolute value of each element in the sequence x to obtain the sequence x*＝[|x1|,|x2|,…,|xN|](ii) a Statistical sequence x*The distribution situation of each element in each subinterval is obtained, thereby obtaining a distribution sequence A*＝[a0,a1,...,aM+1](ii) a Specifically, a00; m is more than or equal to 1 and less than or equal to M, amRepresents a sequence x*The number of elements with a value of not less than (M-1) C/M and less than mC/M; a isM+1Represents a sequence x*The number of elements with values greater than or equal to C; definition of distribution sequence An＝[An,0,An,1,…,An,M+1]And according to distribution sequence A*Calculating distribution sequence AnThe method specifically comprises the following steps: if n is 1, then A1＝A*(ii) a If N is greater than 1 and less than or equal to N, M is greater than or equal to 0 and less than or equal to M, and M is an integer nm', A is an integern,m＝A1,m′(ii) a If N is more than 1 and less than or equal to N, M is more than or equal to 0 and less than or equal to M, and M is not equal to nm', then A isn,m0; if N is greater than 1 and less than or equal to N and M is M +1, then
Figure BDA0002348805690000233
According to distribution sequence AnCalculating distribution sequence BnComprises the following steps:
Figure BDA0002348805690000234
wherein, denotes convolving the two sequences and defining the maximum element number of the resulting sequence as M + 1; specifically, to calculate [ r0,r1,...,rM+1]＝[p0,p1,...,pM+1]◆[q0,q1,...,qM+1]The calculation process is illustrated by way of example. Specifically, the sequence [ p ]0,p1,...,pM+1]And [ q ]0,q1,...,qM+1]Performing convolution operation to obtain the result sequence of v0,v1,...,v2M+2]＝[p0,p1,...,pM+1]*[q0,q1,...,qM+1]Wherein denotes a convolution operation; the maximum element number of the result sequence is limited to M +1, so that
Figure BDA0002348805690000241
2) According to the aboveThe expected undetectable error rate of the optimal decoded codeword is calculated by the number Q and is marked as UERe；
In particular, an undetected error rate is expected
Figure BDA0002348805690000242
Wherein, R is the number of redundant bits in the optimal decoding code word, and Q is the number of bipolar sequences with the distance between the bipolar sequences with the length of N and the sequence x being less than the distance d.
3) If the expected undetectable error rate UEReIf the UER requirement of the system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
specifically, the proximity of the decoded code word to the sequence x can be obtained by counting the number Q of the bipolar sequences with the distance between the bipolar sequences with the length N and the sequence x being smaller than the distance d, so as to obtain the probability that the decoded code word is an effective decoded code word.
In another alternative embodiment, the received sequence x of the code word corresponding to the optimal decoded code word and the mapping sequence are determined according to the UER requirement of the system
Figure BDA0002348805690000243
And the obtained distance d, judge whether the optimum decoding code word is a method of the valid decoding code word, including:
1) obtaining the number Q of bipolar sequences of which the distance between code word receiving sequences corresponding to the optimal decoding code words in all bipolar sequences with the length of N is smaller than or equal to the distance d; wherein, N is the optimal decoding code word length;
2) calculating the expected undetectable error rate UER of the optimal decoding code word according to the obtained bipolar sequence number Qe；
3) If the expected undetectable error rate UEReIf the UER requirement of the communication system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
wherein an undetected error rate is expected
Figure BDA0002348805690000251
And R is the number of redundant bits in the optimal decoding code word.
By the method, the dependence on error detection coding is avoided, the resource overhead of transmitting error detection bits can be reduced, the coding efficiency and the error correction performance can be effectively improved, the limitation of the number of the error detection bits on the control capability of the UER is eliminated, and the control on the undetected error rate of the decoding can be flexibly realized according to the actual requirement of the UER of the system.
The invention provides a communication synchronization method, in the whole process, an expanded synchronization signal does not need to provide signal starting time, modulation center frequency and channel phase information of a sender, control information of a sender does not need to be defined by the sender and the receiver in advance, corresponding synchronization parameters can be changed according to a communication mode, and flexible communication can be realized on the premise of ensuring that channel overhead is small. Further, the receiving end receives, demodulates and decodes the subsequent data signal according to the synchronization parameter obtained by decoding and the calculated start time, modulation center frequency and channel phase of the subsequent data signal, so as to obtain the data sent by the sending end.
In a second aspect, the present invention provides a transmitting module, including a coding unit and a modulation unit;
the coding unit is used for coding the synchronization parameters and the data respectively to obtain synchronization code words and data code words and sending the synchronization code words and the data code words to the modulation unit;
the modulation unit is used for modulating the received synchronous code words and the data code words respectively to form expanded synchronous signals and data signals, and then the expanded synchronous signals and the data signals are sent out in sequence;
the synchronization parameters comprise parameter information of demodulation and decoding data signals, and the parameter information of the demodulation and decoding data signals carried in the synchronization parameters corresponds to the modulation and coding modes of data one to one.
In a third aspect, the present invention provides a receiving module, which includes a demodulating unit, a decoding unit, a judging unit, and a calculating unit;
the demodulation unit is used for receiving and demodulating the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase to obtain synchronous code words and sending the synchronous code words to the decoding unit;
the decoding unit is used for decoding the received synchronous code words, selecting optimal decoding code words from decoding results and sending the optimal decoding code words to the judging unit;
the judging unit is used for judging whether the received optimal decoding code word is effective, if so, the starting time, the modulation center frequency and the channel phase of the current signal are the starting time, the modulation center frequency and the channel phase of the extended synchronous signal, extracting the synchronous parameters in the optimal decoding code word, and sending the synchronous parameters, the starting time, the modulation center frequency and the channel phase of the extended synchronous signal to the calculating unit;
the calculation unit is used for calculating the initial time, the modulation center frequency and the channel phase of the subsequent data signal according to the received synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization.
In a fourth aspect, the present invention provides a communication synchronization system, including the transmitting module proposed in the second aspect of the present invention and the receiving module proposed in the third aspect of the present invention; the transmitting module transmits the signal to the receiving module.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (12)

1. A method of communication synchronization, comprising the steps of:
s1, sending end:
respectively coding the synchronous parameters and the data to obtain synchronous code words and data code words;
modulating the obtained synchronous code words and data code words respectively to form expanded synchronous signals and data signals, and then sequentially sending the expanded synchronous signals and the data signals to a receiving end;
the synchronous parameters comprise parameter information of demodulation and decoding data signals, and the parameter information of the demodulation and decoding data signals carried in the synchronous parameters corresponds to the modulation and coding modes of data one by one;
s2, receiving end:
receiving the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals, respectively decoding the signals, and selecting optimal decoding code words from decoding results;
judging whether the obtained optimal decoding code word is effective, if the optimal decoding code word is effective, the initial time, the modulation center frequency and the channel phase of the current signal are the initial time, the modulation center frequency and the channel phase of the expanded synchronous signal, and extracting the synchronous parameters in the optimal decoding code word;
and calculating the initial time, the modulation center frequency and the channel phase of the data signal to be received subsequently according to the obtained synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization.
2. The communication synchronization method according to claim 1, wherein a receiving end receives, demodulates and decodes the data signal according to the obtained synchronization parameter and the calculated start time, modulation center frequency and channel phase of the data signal to be received subsequently, so as to obtain the data sent by a sending end.
3. The communication synchronization method according to claim 1, wherein the data signal is transmitted immediately after the extended synchronization signal, and a start time of the data signal is equal to a sum of the start time of the extended synchronization signal and a length of the extended synchronization signal.
4. The communication synchronization method according to claim 1, wherein a modulation center frequency of the data signal is the same as a modulation center frequency of the spread synchronization signal.
5. The communication synchronization method according to claim 1, wherein a channel phase of the data signal is the same as a channel phase of the extended synchronization signal.
6. The communication synchronization method of claim 1, wherein the synchronization parameter further comprises a receiver address.
7. The communication synchronization method according to claim 1, wherein the transmitting end performs polar code encoding on the synchronization parameter;
the method for receiving the expanded synchronous signals by the receiving end on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase, demodulating the expanded synchronous signals and then respectively decoding the demodulated expanded synchronous signals to obtain optimal decoding code words comprises the following steps:
s21, performing timing sampling, frequency offset correction and phase correction on the received extended synchronous signal by adopting the combination of the P 'group preset signal start time, the modulation center frequency and the channel phase, and demodulating to obtain P' code word receiving sequences; wherein, P' is the combination number of the signal starting time, the modulation center frequency and the channel phase, and each code receiving sequence corresponds to a group of parameters including the signal starting time, the modulation center frequency and the channel phase;
s22, decoding each P code word receiving sequences in the P code word receiving sequences simultaneously by adopting a multi-code word receiving sequence SCL decoder to obtain P'/P decoding results;
s23, selecting the decoding result with the maximum likelihood probability as the optimal decoding code word according to the maximum likelihood principle for the P '/P decoding results, wherein P is a positive integer smaller than P ', and P '/P is an integer;
in step S22, the method for simultaneously decoding P codeword receiving sequences in P' codeword receiving sequences by using a multiple codeword receiving sequence SCL decoder specifically includes the following steps:
s221, for P to be decodedReceived sequence of individual code words
Figure FDA0003148231880000021
If the index number i of the current decoding bit is equal to its initial value 1, go to S222; if the index number i of the current decoding bit is greater than 1 and less than or equal to N, go to step S223; if the index sequence number i of the current decoding bit is greater than N, go to step S226; wherein, P is less than or equal to L, L is the maximum path number of the preset SCL decoding algorithm, the code receiving sequence is composed of polarization codes, N is the code length of the polarization codes, and i is a positive integer;
s222, initializing P paths in a decoder list, and comparing the first path with the second path
Figure FDA0003148231880000031
The strip path is marked as
Figure FDA0003148231880000032
1,2, P; returning to step S221 by setting i to i + 1; wherein S islIndicates that the code word receiving sequence corresponding to the first path in the decoder list is
Figure FDA0003148231880000033
SlThe initial value of (a) is l,
Figure FDA0003148231880000034
indicating the first bit u of the received sequence of the code word corresponding to the ith path in the decoder list1A decision value of u1Is a fixed bit that is a bit that is fixed,
Figure FDA0003148231880000035
all taking known fixed bits u1Taking the value of (A);
s223, judging the ith bit u in the code receiving sequenceiIf the bit is a fixed bit, go to step S224 if yes; if not, go to step S225;
s224, recording the number of the current paths in the decoder list as L', the first path as
Figure FDA0003148231880000036
1,2,. L'; each path is divided into
Figure FDA0003148231880000037
L' is extended to 1,2
Figure FDA0003148231880000038
L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,
Figure FDA0003148231880000039
indicating the received sequence of code words corresponding to the first path in the decoder list
Figure FDA00031482318800000310
Of decision values, sequence
Figure FDA00031482318800000311
Element (1) of
Figure FDA00031482318800000312
Indicating the l-th path in the decoder list at uiA decision value of (a), and
Figure FDA00031482318800000313
is a known fixed bit uiTaking the value of (A);
s225, sequences in each path
Figure FDA00031482318800000314
At uiThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths
Figure FDA00031482318800000315
And
Figure FDA00031482318800000316
wherein, L1, 2
Figure FDA00031482318800000317
And
Figure FDA00031482318800000318
all correspond to the receiving sequence
Figure FDA00031482318800000319
And the path
Figure FDA00031482318800000320
And
Figure FDA00031482318800000321
the path metric values are respectively
Figure FDA00031482318800000322
And
Figure FDA00031482318800000323
Figure FDA00031482318800000324
and
Figure FDA00031482318800000325
respectively representing the ith bit channel output of a length N polar code as
Figure FDA00031482318800000326
The transition probabilities of 0 and 1 are input in time;
judging whether the 2L 'is less than or equal to L, if so, reserving 2L' paths; if not, keeping the path with the maximum L metric values; and let i equal to i +1, return to step S221;
s226, outputting the corresponding decision sequence on the path with the maximum path metric value from the L paths
Figure FDA0003148231880000041
Obtaining a decoded code word by S recorded on a path corresponding to the decoded code wordlAnd obtaining a code word receiving sequence corresponding to the decoding code word.
8. The communication synchronization method of claim 1, wherein the step of determining whether the optimal decoded codeword is valid comprises:
mapping the obtained optimal decoding code word into a bipolar sequence to obtain a mapping sequence
Figure FDA0003148231880000042
And calculating a mapping sequence
Figure FDA0003148231880000043
The distance d between the codeword receiving sequences x corresponding to the optimal decoding codewords;
obtaining all lengths of N*The number Q of the bipolar sequences with the distance between the code word receiving sequences corresponding to the optimal decoding code words in the bipolar sequences being less than the distance d; wherein N is*The optimal decoding code word length is obtained;
calculating the expected undetectable error rate UER of the optimal decoding code word according to the obtained bipolar sequence number Qe；
If the expected undetectable error rate UEReIf the UER requirement of the communication system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
wherein an undetected error rate is expected
Figure FDA0003148231880000044
And R is the number of redundant bits in the optimal decoding code word.
9. The communication synchronization method of claim 1, wherein the step of determining whether the optimal decoded codeword is valid comprises:
mapping the obtained optimal decoding code word into a bipolar sequence to obtain a mapping sequence
Figure FDA0003148231880000045
And calculating a mapping sequence
Figure FDA0003148231880000046
The distance d between the codeword receiving sequences x corresponding to the optimal decoding codewords;
obtaining all lengths of N*The number Q of the bipolar sequences with the distance between the code word receiving sequences corresponding to the optimal decoding code words in the bipolar sequences is less than or equal to the distance d; wherein N is*The optimal decoding code word length is obtained;
calculating the expected undetectable error rate UER of the optimal decoding code word according to the obtained bipolar sequence number Qe；
If the expected undetectable error rate UEReIf the UER requirement of the communication system is met, the optimal decoding code word is an effective decoding code word; otherwise, the optimal decoding code word is an invalid decoding code word;
wherein an undetected error rate is expected
Figure FDA0003148231880000051
And R is the number of redundant bits in the optimal decoding code word.
10. A receiving module, comprising: a demodulation unit, a decoding unit, a judgment unit and a calculation unit;
the demodulation unit is used for receiving and demodulating the expanded synchronous signals on the combination of a plurality of groups of preset signal starting time, modulation center frequency and channel phase to obtain synchronous code words and sending the synchronous code words to the decoding unit;
the decoding unit is used for decoding the received synchronous code words, selecting optimal decoding code words from decoding results and sending the optimal decoding code words to the judging unit;
the judging unit is used for judging whether the received optimal decoding code word is effective, if so, the starting time, the modulation center frequency and the channel phase of the current signal are the starting time, the modulation center frequency and the channel phase of the extended synchronous signal, extracting the synchronous parameters in the optimal decoding code word, and sending the synchronous parameters, the starting time, the modulation center frequency and the channel phase of the extended synchronous signal to the calculating unit;
the calculation unit is used for calculating the initial time, the modulation center frequency and the channel phase of the subsequent data signal to be received according to the received synchronization parameters and the initial time, the modulation center frequency and the channel phase of the expanded synchronization signal, so as to realize communication synchronization.
11. A transmitting module based on the receiving module of claim 10, comprising: a coding unit and a modulation unit;
the coding unit is used for coding the synchronization parameters and the data respectively to obtain synchronization code words and data code words and sending the synchronization code words and the data code words to the modulation unit;
the modulation unit is used for modulating the received synchronous code words and the data code words respectively to form expanded synchronous signals and data signals, and then sequentially sending the expanded synchronous signals and the data signals to the receiving module;
the synchronization parameters comprise parameter information of demodulation and decoding data signals, and the parameter information of the demodulation and decoding data signals carried in the synchronization parameters corresponds to the modulation and coding modes of data one to one.
12. A communication synchronization system, comprising: the transmitting module of claim 11 and the receiving module of claim 10;
the transmitting module transmits a signal to the receiving module.
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