CN111106838A

CN111106838A - Communication synchronization method, device and system

Info

Publication number: CN111106838A
Application number: CN201911406621.9A
Authority: CN
Inventors: 屈代明
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-05-05
Anticipated expiration: 2039-12-31
Also published as: CN111106838B

Abstract

The invention discloses a communication synchronization method, device and system. Before sending a data signal, an extended synchronization signal carrying demodulated and decoded data signal parameter information is sent first. Based on the extended synchronization signal, the sending end can easily calculate When the control information of the data signal is obtained, it is not necessary to pre-agreed with the sending end the control information, and communication in different ways can be realized by changing the synchronization parameters, thereby greatly improving the flexibility of communication. In addition, the extended synchronization signal does not need to provide the sender's signal start time, modulation center frequency and channel phase information. After the signal is demodulated and decoded, the start time, modulation center frequency and channel phase of the extended synchronization signal are determined by checking the validity of the decoding result, which saves a lot of spectrum resources and can ensure that the channel overhead is small. to achieve flexible communication.

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

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 setting the l (l is 1, 2),., P) paths are recorded

Returning to step S221 by setting i to i + 1; wherein S is_lIndicates that the code word receiving sequence corresponding to the first path in the decoder list is

S_lThe initial value of (a) is l,

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,

all taking known fixed bits u₁Taking the value of (A);

s223, judging the ith bit u in the code receiving sequence_iIf 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 ″

Each path is divided into

L' is extended to 1,2

L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,

indicating the received sequence of code words corresponding to the first path in the decoder list

Is determined by the decision value ofSequence of

Element (1) of

Indicating the l-th path in the decoder list at u_iA decision value of (a), and

is a known fixed bit u_iTaking the value of (A);

s225, sequences in each path

At u_iThe positions are respectively taken as values 0 and 1 to obtain 2L' alternative paths

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

respectively representing the ith bit channel output of a length N polar code as

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

Obtaining a decoded code word by S recorded on a path corresponding to the decoded code word_lAnd 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

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

S_lThe initial value of (a) is l,

all taking known fixed bits u₁Taking the value of (A);

Each path is divided into

L' is extended to 1,2

L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,

Of decision values, sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iA decision value of (a), and

is a known fixed bit u_iTaking the value of (A);

s225, sequences in each path

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

The transition probabilities of 0 and 1 are input in time;

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

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

If the index number i of the current decoding bit is equal to the initial value 1, go to S222; if the index sequence of the current decoding bitIf the number i is greater than 1 and less than or equal to N, the process goes 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;

S_lThe initial value of (a) is l,

all taking known fixed bits u₁Taking the value of (A);

Each path is divided into

L' is extended to 1,2

l＝1,2,...,L′，Returning to step S221 by setting i to i + 1; wherein,

Of decision values, sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iA decision value of (a), and

is a known fixed bit u_iTaking the value of (A);

s225, if u_iFor information bits, sequences in each path

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

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 u_iTo check the bits, each path is mapped

Is extended to

Returning to step S221 by setting i to i + 1; wherein, the sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iAnd wherein

Is taken according to u_iThe check equation and the result of the information bit judged on the l path in the equation are checked;

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

Last bit u in^NIs 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

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;

S_lThe initial value of (a) is l,

all taking known fixed bits u₁Taking the value of (A);

Each path is divided into

L' is extended to 1,2

L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,

Of decision values, sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iA decision value of (a), and

is a known fixed valueBit u_iTaking the value of (A);

s225, sequences in each path

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

The transition probabilities of 0 and 1 are input in time;

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

And calculating a mapping sequence

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

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

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 expected undetectable error rate UER of the optimal decoding code word according to the obtained bipolar sequence number Q_e；

If the expected undetectable error rate UER_eIf 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

And R is the number of redundant bits in the optimal decoding code word.

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;

wherein an undetected error rate is expected

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:

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

Bit u₁To u_NSequentially transmitting on the 1 st to the Nth bit channels, and the polar code non-fixed bit channel sequence number set is

M is a positive integer, and the fixed bit channel sequence number set is marked as A^c. The elements in the set A satisfy a when i is more than 1 and less than j and less than M_i＜a_j. The non-fixed bit sequence is denoted as

The fixed bits of the polarization code are known at both the transmitting and receiving ends, the fixed bit sequence

Set to all 0 s. The polarization code is coded into

G_NA matrix is generated for the polarization code.

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

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 timesStart 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 M for modulation center frequency₂4 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 N_p110, 4 sampling output signals can be obtained

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

Wherein l is ∈ [1,4 ]]，w_i＝r_(i-1)×8+l. Sampling the obtained 4 channels to output signal

Separately performing frequency offset correction, wherein each output signal is

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

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

Will signal

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

S_lThe initial value of (a) is l,

all taking known fixed bits u₁Taking the value of (A);

Each path is divided into

L' is extended to 1,2

L ═ 1, 2., L', let i ═ i +1, return to step S221; wherein,

Of decision values, sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iThe decision value of (a) is determined,and is

Is a known fixed bit u_iTaking the value of (A);

s225, sequences in each path

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

respectively representing the ith polar code of length NA bit channel output of

The transition probabilities of 0 and 1 are input in time;

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

Obtaining a decoded code word by S recorded on a path corresponding to the decoded code word_lAnd 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 sender 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, where 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 dynamics Letters, vol.20, No.12, pp.2342-2345, 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

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 u_iFor information bits, sequences in each path

And

wherein, L1, 2

And

all correspond to the receiving sequence

And the path

And

the path metric values are respectively

And

and

if u_iTo check the bits, each path is mapped

Is extended to

Returning to step S221 by setting i to i + 1; wherein, the sequence

Element (1) of

Indicating the l-th path in the decoder list at u_iAnd wherein

Is taken according to u_iAnd 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 an alternative embodiment 6, when the sending end performs the polar code encoding on the synchronization parameter, the sequence input into the polar code encoder is used

Last bit u in^NIs 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

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

Last bit u of^NIs a fixed bit and skips the last bit u in the decoding process^NThe 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

Wherein N represents the length of the code of the polarization code, vector

Representing polar code words, c_i(i ═ 1, 2.. times.n) denotes the ith coded bit, the vector

From two sub-vectors u_A＝(u_iI ∈ A) and

composition, set

Non-fixed set of bit indices, called polar codes

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 u_ASet as information bit sequence, sub-vector

The fixed bit sequence known to the receiving end is set to be a sequence of all 0's. According to u_AAnd

determining a vector

And coding to obtain polarization code word

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:

And calculating a mapping sequence

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

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

The distance between the received sequences x of code words corresponding to the optimal decoded code words is specifically Euclidean distance, and the distance

According to UER requirement of system, receiving sequence x and mapping sequence of code word corresponding to optimum decoding code word

In an alternative embodiment, the optimization is based on the UER requirements of the systemCode word receiving sequence x and mapping sequence corresponding to decoding code word

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

In, calculate satisfied with

The number of bipolar sequences Q. By analyzing the above formula, record

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

Is calculated to satisfy

Due to the number of bipolar sequences

The above problem can be further translated into, in all bipolar sequences

In, calculate satisfied with

The number of bipolar sequences of (a); and can be further converted to, in all bipolar sequences

In, calculate satisfied with

The number Q of bipolar sequences of (2), wherein,

representing a sequence

And

a set of sequence numbers of non-identical elements,

representing bipolar sequences

And bipolar sequences

A set of sequence numbers of non-identical elements. Due to the fact that

Is a constant number, memory

Solving the problem of the number Q is further convertible to

In, calculate satisfied with

The number of bipolar sequences of (a); to sum up, the problem of finally solving the number Q can be converted into an in-orderIn the subset S of the sequence numbers a ═ {1,2, …, N } of all elements in the column x, the calculation satisfies

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,…,x_N]Bipolar sequence of (2)

In particular, bipolar sequences

Of (2) element(s)

The acquisition mode is as follows: if x_gIs not less than 0, then

If not, then,

where g ∈ {1,2, …, N }.

1.2) introduction of Bipolar sequences

And mapping sequences

Comparing to obtain the serial number sets of elements which are not identical in the two sequences

1.3) according toSet of sequence numbers

Screening out corresponding elements from the sequence x, and calculating the sum of absolute values of the screened elements to obtain a constant

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

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

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 B_n＝[B_n,0,B_n,1,…,B_n,M+1](ii) a According to distribution sequence B_nCalculating the number of subsets Q^*Comprises the following steps:

wherein N belongs to {1,2, …, N }; and distribution sequence B_nThe acquisition mode is specifically as follows: taking absolute value of each element in the sequence x to obtain the sequence x^*＝[|x₁|,|x₂|,…,|x_N|](ii) a Statistical sequence x^*The distribution condition of each element in each subinterval is obtained, thereby obtaining the distribution orderColumn A^*＝[a₀,a₁,...,a_M+1](ii) a Specifically, a₀0; m is more than or equal to 1 and less than or equal to M, a_mRepresents a sequence x^*The number of elements with a value of not less than (M-1) C/M and less than mC/M; a is_M+1Represents a sequence x^*The number of elements with values greater than or equal to C; definition of distribution sequence A_n＝[A_n,0,A_n,1,…,A_n,M+1]And according to distribution sequence A^*Calculating distribution sequence A_nThe 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 integer_n,m＝A_1,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 is_n,m0; if N is greater than 1 and less than or equal to N and M is M +1, then

According to distribution sequence A_nCalculating distribution sequence B_nComprises the following steps:

wherein ◆ denotes convolving the two sequences and defining the maximum element number of the resulting sequence as M +1, specifically to calculate [ r [ -r ]₀,r₁,...,r_M+1]＝[p₀,p₁,...,p_M+1]◆[q₀,q₁,...,q_M+1]The calculation process is illustrated by way of example. Specifically, the sequence [ p ]₀,p₁,...,p_M+1]And [ q ]₀,q₁,...,q_M+1]Performing convolution operation to obtain the result sequence of v₀,v₁,...,v_2M+2]＝[p₀,p₁,...,p_M+1]*[q₀,q₁,...,q_M+1]Wherein denotes a convolution operation; the maximum element number of the result sequence is limited to M +1, so that

2) Calculating the expected undetected error rate of the optimal decoding code word according to the number Q, and recording the rate as UER_e；

In particular, an undetected error rate is expected

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 UER_eIf 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

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 Q_e；

3) If the expected undetectable error rate UER_eIf 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

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.

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

1. a communication synchronization method, is characterized in that, comprises the following steps:

S1. Sender:

The synchronization parameters and data are encoded respectively to obtain the synchronization codeword and the data codeword;

The obtained synchronization code word and data code word are modulated respectively to form an extended synchronization signal and a data signal, which are then sent to the receiving end in turn;

Wherein, the synchronization parameter includes parameter information of the demodulated and decoded data signal, and the parameter information of the demodulated and decoded data signal carried in the synchronization parameter corresponds to the modulation and coding modes of the data one-to-one;

S2. Receiver:

Receive extended synchronization signals on multiple preset combinations of signal start time, modulation center frequency and channel phase, demodulate them, and decode them respectively, and select the optimal decoding from the decoding results numbers;

Determine whether the obtained optimal decoding codeword is valid. If the optimal decoding codeword is valid, the start time, modulation center frequency and channel phase of the current signal are the start time, modulation center frequency and channel phase of the extended synchronization signal. , and extract the synchronization parameters in the optimal decoding codeword;

According to the obtained synchronization parameters and the start time, modulation center frequency and channel phase of the extended synchronization signal, the start time, modulation center frequency and channel phase of the subsequent data signal are calculated to achieve communication synchronization.

2. communication synchronizing method according to claim 1 is characterized in that, the receiving terminal receives the subsequent data signal according to the starting time, modulation center frequency and channel phase of the obtained synchronization parameter and the calculated follow-up data signal, Demodulate and decode to get the data sent by the sender.

3. The communication synchronization method according to claim 1, wherein the data signal is sent immediately after the extension synchronization signal, and the start time of the data signal is equal to the start time of the extension synchronization signal and the extension synchronization signal. The sum of the lengths of the extended synchronization signals.

4 . The communication synchronization method according to claim 1 , wherein the modulation center frequency of the data signal is the same as the modulation center frequency of the extended synchronization signal. 5 .

5. The communication synchronization method according to claim 1, wherein the channel phase of the data signal is the same as the channel phase of the extended synchronization signal.

6 . The communication synchronization method according to claim 1 , wherein the synchronization parameter further comprises a receiver address. 7 .

7. The communication synchronization method according to claim 1, wherein the transmitting end performs polar code coding on the synchronization parameters;

The receiving end receives the extended synchronization signal on a combination of multiple groups of preset signal start times, modulation center frequencies and channel phases, and after demodulating them, respectively performs decoding to obtain an optimal decoding codeword. The method includes the following steps: The following steps:

S21. Using the preset combination of signal start time, modulation center frequency and channel phase in the P' group, perform timing sampling, frequency offset correction and phase correction processing on the received extended synchronization signal, and obtain P' after demodulation Codeword receiving sequence; wherein, P' is the number of combinations of signal start time, modulation center frequency and channel phase, and each codeword reception sequence corresponds to a set of parameters including signal start time, modulation center frequency and channel phase;

S22, using a multi-codeword receiving sequence SCL decoder to simultaneously decode each P codeword receiving sequence in the P' codeword receiving sequences to obtain P'/P decoding results;

S23. For the obtained P'/P decoding results, select the decoding result with the largest likelihood probability as the optimal decoding code word according to the principle of maximum likelihood, where P is a positive integer smaller than P', and P' /P is an integer;

Wherein, in the step S22, a method for simultaneously decoding the P codeword reception sequences in the P' codeword reception sequences by using a multi-codeword reception sequence SCL decoder specifically includes the following steps:

S221, receiving sequences for the P codewords to be decoded

If the index number i of the current decoded bit is equal to its initial value 1, go to S222; if the index number i of the current decoded bit is greater than 1 and less than or equal to N, go to step S223; if the index number i of the current decoded bit is is greater than N, go to step S226; wherein, P≤L, L is the maximum number of paths of the preset SCL decoding algorithm, the codeword receiving sequence is composed of polar codes, N is the code length of polar codes, and i is a positive integer ;

S222, initialize P paths in the decoder list, and record the lth (l=1, 2, . . . , P) path as

Let i=i+1, return to step S221; wherein, S1 represents that the codeword receiving sequence corresponding to the _lth path in the decoder list is

The initial value of S _l is l,

Indicates the decision value of the first bit u ₁ of the codeword received sequence corresponding to the lth path in the decoder list, where u ₁ is a fixed bit,

The value of is the known value of the fixed bit u ₁ ;

S223, determine whether the _i -th bit ui in the codeword receiving sequence is a fixed bit, if so, go to step S224; if not, go to step S225;

S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

expands to

Let i=i+1, return to step S221; wherein,

Indicates the received sequence of codewords corresponding to the lth path in the decoder list

The decision value of , the sequence

elements in

represents the decision value of the lth path in the decoder list at _ui , and

The value of is the value of the known fixed bit _ui ;

S225. Set the sequence in each path

Take the values 0 and 1 at u _i , respectively, to obtain 2L' alternative paths

and

Among them, l=1,2,...,L', the path

and

Both correspond to the receive sequence

and the path

and

The path metrics of , respectively, are

and

and

Respectively, the output of the i-th bit channel of the polar code of length N is

Enter the transition probabilities of 0 and 1, respectively;

Determine whether 2L' is less than or equal to L, and if so, keep 2L' paths; if not, keep L paths with the largest metric value; and set i=i+1, and return to step S221;

S226, output the decision sequence corresponding to the one path with the largest path metric value from the L paths

_The decoded codeword is obtained, and the received sequence of the codeword corresponding to the decoded codeword is obtained through S1 recorded on the path corresponding to the decoded codeword.

8. The communication synchronization method according to claim 1, wherein the method for judging whether the optimal decoding codeword is effective, comprises:

Mapping the obtained optimal decoding codewords into bipolar sequences to obtain the mapping sequence

and compute the mapping sequence

The distance d between the received sequence x of codewords corresponding to the optimally decoded codewords;

Obtain the number Q of bipolar sequences whose distances between the received sequences of codewords corresponding to the optimal decoding codewords in all bipolar sequences of length N are less than the distance d; where N is the optimal decoding codeword length;

According to the obtained bipolar sequence number Q, calculate the expected undetectable error rate UER _e of the optimal decoding codeword;

If the expected undetectable error rate UER _e meets the UER requirement of the communication system, the optimal decoding codeword is an effective decoding codeword; otherwise, the optimal decoding codeword is an invalid decoding codeword;

where the expected undetectable error rate

R is the number of redundant bits in the optimal decoding codeword.

9. The communication synchronization method according to claim 1, wherein the method for judging whether the optimal decoding codeword is effective, comprises:

and compute the mapping sequence

Obtain the number Q of bipolar sequences whose distances between the received sequences of codewords corresponding to the optimal decoding codewords in all bipolar sequences of length N are less than or equal to the distance d; among them, N is the optimal decoding codeword. code word length;

where the expected undetectable error rate

R is the number of redundant bits in the optimal decoding codeword.

10. A sending module, comprising: a coding unit and a modulation unit;

The encoding unit is used to encode the synchronization parameter and the data, respectively, to obtain a synchronization codeword and a data codeword, and send them to the modulation unit;

The modulation unit is used to modulate the received synchronization code word and the data code word respectively, form an extended synchronization signal and a data signal, and then send them out in turn;

The synchronization parameter includes parameter information of the demodulated and decoded data signal, and the parameter information of the demodulated and decoded data signal carried in the synchronization parameter corresponds to the modulation and coding modes of the data one-to-one.

11. A receiving module, comprising: a demodulation unit, a decoding unit, a judgment unit and a calculation unit;

The demodulation unit is used to receive and demodulate the extended synchronization signal on the combination of multiple preset signal start times, modulation center frequencies and channel phases, to obtain a synchronization codeword, and send it to the decoding unit;

The decoding unit is used to decode the received synchronization codeword, and select the optimal decoding codeword from the decoding result, and send it to the judgment unit;

The judging unit is used to judge whether the received optimal decoding codeword is valid, if valid, then the starting time, modulation center frequency and channel phase of the current signal are the starting time, modulation center frequency and channel phase of the extended synchronization signal. channel phase, extract the synchronization parameter in the optimal decoding codeword, and send the synchronization parameter and the start time of the extended synchronization signal, the modulation center frequency and the channel phase to the calculation unit;

The calculation unit is used for calculating the start time, modulation center frequency and channel phase of the subsequent data signal according to the received synchronization parameters and the start time, modulation center frequency and channel phase of the extended synchronization signal, so as to realize communication synchronization.

12. A communication synchronization system, characterized in that, comprising: the sending module of claim 10 and the receiving module of claim 11;

The sending module sends a signal to the receiving module.