CN111106838B - A communication synchronization method, device and system - Google Patents

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

A communication synchronization method, device and system

technical field

The present invention belongs to the field of wireless communication, and more particularly, relates to a communication synchronization method, device and system.

Background technique

To complete a successful communication, the sender and receiver of communication need to be completely synchronized. With the progress of society and the development of science and technology, people have higher and higher requirements for communication quality. Therefore, it is important to study communication synchronization methods, devices and systems. meaning.

In order to keep the sender and receiver fully synchronized, the receiver needs to know the sender's signal start time, modulation center frequency, channel phase, and the coding, puncturing, interleaving, modulation, spreading/frequency hopping, Filter parameters and other information. In the existing communication synchronization method, a synchronization signal and a control word are embedded in the communication signal to be sent, wherein the synchronization signal provides the receiver with the signal start time, modulation center frequency and channel phase of the sender; Necessary parameter information for codeword demodulation and decoding, such as data codeword modulation method, coding method, symbol rate, data length, codeword length, the difference between the start time of the data codeword and the end time of the synchronization codeword, Modulation center frequency and parameter information such as puncturing, interleaving, spreading, frequency hopping, filtering, etc. Although the synchronization signal can achieve synchronization between the receiver and the transmitter, it will occupy a large overhead and waste a lot of spectrum resources. In addition, because the synchronization signal is a fixed signal, it is easy for the observer to grasp the transmission and reception by detecting the synchronization signal. The ongoing communication behavior of the dual transmission leads to a decrease in the confidentiality and security of the communication. In addition, due to the different coding and modulation methods of data signals in the transmitting end, the control words are also different. However, in order to save overhead, in most communication systems, the receiving and transmitting parties usually negotiate this information in advance, thereby greatly reducing the cost of flexibility of communication. It can be seen from the above that the existing communication synchronization methods cannot take into account both the channel overhead and the flexible communication.

SUMMARY OF THE INVENTION

In view of the above defects or improvement requirements of the prior art, the present invention provides a communication synchronization method, the purpose of which is to solve the problem in the prior art that the synchronization signal needs to provide the sender's signal start time, modulation center frequency and channel phase information, In addition, the control word needs to be agreed in advance by both the receiver and the sender, which leads to the technical problem that the channel overhead and flexible communication cannot be taken into account.

In order to achieve the above object, in a first aspect, the present invention provides a communication synchronization method, comprising 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.

Further preferably, the receiving end receives, demodulates and decodes the subsequent data signal according to the obtained synchronization parameters and the calculated starting time, modulation center frequency and channel phase of the subsequent data signal to obtain the data sent by the transmitting end.

Further preferably, the data signal is sent 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 extended 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 the address of the receiver.

Further preferably, the transmitting end performs polar code encoding 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 a combination of multiple groups of preset signal start times, modulation center frequencies and channel phases, perform timing sampling, frequency offset correction and phase correction processing on the received extended synchronization signal, and obtain P' codes after demodulation word reception sequence; wherein, P' is the number of combinations of signal start time, modulation center frequency and channel phase, and each code word 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.

Further preferably, in 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, includes the following steps:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N，则转至步骤S223；若当前译码比特的索引序号i大于N，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为极化码码长，i为正整数；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 ;

令i＝i+1，返回步骤S221；其中，S_l表示译码器列表中第l条路径所对应的码字接收序列为

S_l的初始取值为l，

表示译码器列表中第l条路径对应的码字接收序列的第一个比特u₁的判决值，u₁是固定比特，

的取值均为已知的固定比特u₁的取值；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;

将每条路径

l＝1,2,...,L′扩展为

l＝1,2,...,L′，令i＝i+1，返回步骤S221；其中，

表示译码器列表中第l条路径对应的码字接收序列

的判决值，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且

的取值为已知的固定比特u_i的取值；S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

l=1,2,...,L' expands to

l=1,2,...,L', 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 ;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；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;

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。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.

Further preferably, the transmitting end concatenates the CRC encoding before the polar code encoding, and performs the CRC concatenated polar code encoding on the synchronization parameter; in step S22, the multi-codeword receiving sequence SCL decoder is used to receive the P' codewords. The method for simultaneously decoding the P codewords in the received sequence comprises the following steps:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N，则转至步骤S223；若当前译码比特的索引序号i大于N，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为极化码码长，i为正整数；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 ;

令i＝i+1，返回步骤S221；其中，S_l表示译码器列表中第l条路径所对应的码字接收序列为

S_l的初始取值为l，

表示译码器列表中第l条路径对应的码字接收序列的第一个比特u₁的判决值，u₁是固定比特，

的取值均为已知的固定比特u₁的取值；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;

将每条路径

l＝1,2,...,L′扩展为

l＝1,2,...,L′，令i＝i+1，返回步骤S221；其中，

表示译码器列表中第l条路径对应的码字接收序列

的判决值，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且

的取值为已知的固定比特u_i的取值；S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

l=1,2,...,L' expands to

l=1,2,...,L', 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 ;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；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;

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。S226, output the decision sequence corresponding to a path that satisfies the CRC check and has 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.

Further preferably, the receiving end judges whether the optimal decoding codeword exists and satisfies the CRC check, and if it exists and satisfies the CRC check, the optimal decoding codeword is valid.

Further preferably, the transmitting end concatenates the verification code and the polar code, and performs the verification and concatenated polar code encoding on the synchronization parameter; in step S22, a multi-codeword receiving sequence SCL decoder is used to perform a multi-codeword receiving sequence SCL decoder to P' codewords. The method for simultaneously decoding the P codewords in the received sequence includes the following steps:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N，则转至步骤S223；若当前译码比特的索引序号i大于N，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为校验级联极化码码长，i为正整数；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 the check concatenated polar code, i is a positive integer;

令i＝i+1，返回步骤S221；其中，S_l表示译码器列表中第l条路径所对应的码字接收序列为

S_l的初始取值为l，

表示译码器列表中第l条路径对应的码字接收序列的第一个比特u₁的判决值，u₁是固定比特，

的取值均为已知的固定比特u₁的取值；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;

将每条路径

l＝1,2,...,L′扩展为

l＝1,2,...,L′，令i＝i+1，返回步骤S221；其中，

表示译码器列表中第l条路径对应的码字接收序列

的判决值，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且

的取值为已知的固定比特u_i的取值；S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

l=1,2,...,L' expands to

l=1,2,...,L', 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 ;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；判断2L′是否小于等于L，若是，保留2L′条路径；若否，则保留其中L条度量值最大的路径；并令i＝i+1，返回步骤S221；S225. If _ui is an information bit, 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

When inputting the transition probabilities of 0 and 1 respectively; judge whether 2L' is less than or equal to L, if so, keep 2L'paths; if not, keep the L paths with the largest metric value; and let i=i+1, return Step S221;

扩展为

令i＝i+1，返回步骤S221；其中，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且其中

的取值根据u_i所在校验方程和该方程中信息比特在第l条路径上已判决的结果校验得到；If u _i is the check bit, then each path will be

expands to

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

elements in

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

The value of u _i is obtained according to the verification equation where u i is located and the result of the judgment of the information bits in the equation on the lth path;

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。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.

中的最后一个比特u^N为固定比特；此时，步骤S22中采用多码字接收序列SCL译码器对P′个码字接收序列中的P个码字接收序列同时进行译码的方法，包括以下步骤：Further preferably, when the transmitting end performs polar code encoding on the synchronization parameters, the sequence of the input polar code encoder is

The last bit u ^N in is a fixed bit; at this time, in step S22, a method of simultaneously decoding the P codeword reception sequences in the P' codeword reception sequences is performed by the multi-codeword reception sequence SCL decoder, Include the following steps:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N-1，则转至步骤S223；若当前译码比特的索引序号i大于N-1，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为极化码码长，i为正整数；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-1, go to step S223; if the index of the current decoded bit is If the serial number i is greater than N-1, 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 length of polar codes, i is a positive integer;

令i＝i+1，返回步骤S221；其中，S_l表示译码器列表中第l条路径所对应的码字接收序列为

S_l的初始取值为l，

表示译码器列表中第l条路径对应的码字接收序列的第一个比特u₁的判决值，u₁是固定比特，

的取值均为已知的固定比特u₁的取值；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;

将每条路径

l＝1,2,...,L′扩展为

l＝1,2,...,L′，令i＝i+1，返回步骤S221；其中，

表示译码器列表中第l条路径对应的码字接收序列

的判决值，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且

的取值为已知的固定比特u_i的取值；S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

l=1,2,...,L' expands to

l=1,2,...,L', 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 ;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；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;

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。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.

Further preferably, the method for judging whether the optimal decoding codeword is valid, comprises:

并计算映射序列

与最优译码码字对应的码字接收序列x之间的距离d；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;

以及所得距离d，判断最优译码码字是否为有效译码码字。According to the Undetectable Error Rate (UER) requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

and the obtained distance d to determine whether the optimal decoded codeword is a valid decoded codeword.

以及所得距离d，判断最优译码码字是否为有效译码码字的方法，包括：Further preferably, according to the UER requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

And the obtained distance d, the method for judging whether the optimal decoding codeword is an effective decoding codeword, including:

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;

R为最优译码码字中冗余比特的个数。where the expected undetectable error rate

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

以及所得距离d，判断最优译码码字是否为有效译码码字的方法，包括：Further preferably, according to the UER requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

And the obtained distance d, the method for judging whether the optimal decoding codeword is an effective decoding codeword, including:

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;

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;

R为最优译码码字中冗余比特的个数。where the expected undetectable error rate

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

In a second aspect, the present invention provides a sending module, including an encoding unit and a modulation unit;

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

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

The synchronization parameters include parameter information of the demodulated and decoded data signals, and 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.

In a third aspect, the present invention provides a receiving module, including 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 code word and send it to the decoding unit;

The decoding unit is used for decoding the received synchronization codeword, and selects the optimal decoding codeword from the decoding result, and sends it to the judgment unit;

The judgment unit is used to judge whether the received optimal decoding codeword is valid. If 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. , extract the synchronization parameters in the optimal decoding codeword, and send the synchronization parameters and the start time, modulation center frequency and channel phase of the extended synchronization signal to the calculation unit;

The calculation unit is used to calculate 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.

In a fourth aspect, the present invention provides a communication synchronization system, including the sending module proposed in the second aspect of the present invention and the receiving module proposed in the third aspect of the present invention; the sending module sends a signal to the receiving module.

In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. The present invention proposes a communication synchronization method. Before sending a data signal, an extended synchronization signal is sent first. Because the extended synchronization signal carries the parameter information for demodulating and decoding the data signal, and the carried parameter information for the demodulating and decoding data signal corresponds to the modulation and coding mode of the data, so based on the extended synchronization signal, the transmitting end can easily The control information of the data signal is obtained by calculating the data signal, and there is no need to agree on the control information with the sender in advance. By changing the synchronization parameters, different modes of communication can be realized, thereby greatly improving the flexibility of communication. In addition, in the extended synchronization signal of the present invention, there is no need to additionally provide the receiving end with the signal starting time, modulation center frequency and channel phase of the transmitting end. Receive the extended synchronization signal on the phase combination, demodulate and decode it, and further check the validity of the obtained decoding result to determine whether the current combination corresponds to the start time, modulation center frequency and channel phase of the extended synchronization signal. , so as to further calculate the start time, modulation center frequency and channel phase of the subsequent data signal, realize the communication synchronization between the receiver and the sender, greatly reduce the overhead occupation, and save a lot of spectrum resources. It can be seen from the above that the method provided by the present invention can realize flexible communication on the premise of ensuring that the channel overhead is small.

2. In the communication synchronization method proposed by the present invention, the extended synchronization signal is a non-fixed signal, and the synchronization parameters in it change with the change of the communication mode, so that the observer cannot grasp the ongoing transmission and reception by detecting the synchronization signal. Communication behavior, confidentiality and security are high.

3. The communication synchronization method proposed by the present invention, the method for verifying the validity of the obtained decoding result avoids the dependence on error detection coding, can reduce the resource overhead of transmitting error detection bits, thereby effectively improving coding efficiency and error correction. It also eliminates the limitation of the number of error detection bits on the UER control capability, and can flexibly control the undetectable error rate of decoding according to the actual system UER requirements.

Description of drawings

Fig. 1 is the flow chart of the communication synchronization method provided by the present invention;

FIG. 2 is a schematic diagram of a signal sent by a transmitter provided by the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

In order to achieve the above object, in the first aspect, the present invention provides a communication synchronization method, as shown in FIG. 1 , comprising 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;

Among them, the synchronization parameters include parameter information for demodulating and decoding the data signal, such as the modulation mode, encoding mode, symbol rate, data length, codeword length, start time of the data codeword and end time of the synchronization codeword of the data codeword difference, modulation center frequency, and parameter information such as puncturing, interleaving, spectrum spreading, frequency hopping, filtering, etc.; the parameter information of the demodulated and decoded data signal carried in the synchronization parameter corresponds to the modulation and coding mode of the data. Preferably, the synchronization parameter further includes the address of the receiver.

Specifically, the method at the transmitting end may use polar code coding, check concatenated polar code coding and other methods to encode the synchronization parameters. In an optional embodiment 1, the transmitting end performs polar code encoding on the synchronization parameter. Among them, the synchronization parameter contains 16 information bits, of which 8 bits are the address of the receiver, and the other 8 bits are the parameter information for demodulating and decoding the data signal. rate, data length. The modulation mode of the data code word occupies 2 bits, and in this embodiment, the value is 01, indicating that QPSK is used to modulate the data code word. The encoding mode of the data occupies 1 bit, and in this embodiment, the value is 1, indicating that LDPC is used to encode the data; the symbol rate occupies 2 bits, and in this embodiment, the value is 01, indicating that the symbol rate is 2MHz; The data length occupies 3 bits, and the value is 100 in this embodiment, indicating that the data length is 1024 bits. Perform polar code coding on the above synchronization parameters to obtain 64 coded bits, and use BPSK to modulate the obtained synchronization codeword with a symbol rate of 1MHz, modulate it to a center frequency of 500MHz, and send it to the receiving end.

The data signal can be sent immediately after the extended synchronization signal, or the extended synchronization signal can be sent after a period of time. When the extended synchronization information is sent after a period of time, the interval time is added to the synchronization parameter, so that the sender can calculate the data signal. Start time, communication is more 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 sent 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.

In this embodiment, after the extended synchronization signal is sent, the data signal is sent immediately, as shown in FIG. 2 . The modulation and coding modes of the data correspond one-to-one with the parameter information of the demodulated and decoded data signals carried in the synchronization parameters. Specifically, the transmitting end performs LDPC encoding on the data to be sent, the code word length is 1024 coded bits, and then uses QPSK to modulate the data code word. 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. When they are not the same, the difference between the two needs to be added to the synchronization parameters, so that the sender can easily calculate The corresponding information of the corresponding data signal is output, and the communication is more flexible. In this embodiment, the modulation center frequency and channel phase of the data signal are the same as those of the extended synchronization signal, and the symbol rate is 1 MHz, which is also modulated at the center frequency of 500 MHz for transmission.

In the above manner, the sender can easily calculate the control information of the data signal according to the received extended synchronization signal, without having to agree on the control information in advance with the sender. flexibility. In addition, the extended synchronization signal provided by the present invention is a non-fixed signal, in which the synchronization parameter changes with the change of the communication mode, so that the observer cannot grasp the ongoing communication behavior of the transceiver and the transmission by detecting the synchronization signal. High security.

It should be noted that the synchronization parameters include the above-mentioned modulation mode of the data code word, data encoding mode, symbol rate, data length, the difference between the start time of the data signal and the end time of the extended synchronization signal, the difference between the data signal and the data signal. The difference between the modulation center frequency, channel phase, and symbol rate of the extended synchronization signal, and the necessary parameters for demodulating and decoding the data signal, including puncturing, interleaving, spreading, frequency hopping, filtering, etc. any parameter in .

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 codeword; specifically, in an optional manner, for the obtained decoding result, the decoding result with the largest likelihood probability is selected from the obtained decoding result according to the principle of maximum likelihood, as the optimal decoding codeword;

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 decoded codeword; in addition, in an optional implementation manner, if the optimal decoded codeword is invalid, go to step S1, and the transmitting end resends the signal.

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. Specifically, when the data signal is not sent immediately following the extended synchronization signal, or the modulation center frequency or channel phase of the data signal and the extended synchronization signal are not the same, the synchronization parameter correspondingly includes the difference between the corresponding parameters of the two, and the obtained extended synchronization The starting time, modulation center frequency and channel phase of the synchronization signal are added to the difference of the corresponding parameters in the synchronization parameters, and the corresponding information of the corresponding data signal can be easily calculated, thereby realizing the communication synchronization between the receiver and the sender. .

比特u₁到u_N依次在第1个到第N个比特信道上发送，极化码非固定比特信道序号集合为

M为正整数，固定比特信道序号集合记为A^c。集合A中的元素满足当1≤i＜j≤M时，a_i＜a_j。非固定比特序列记为

极化码固定比特在收发两端已知，固定比特序列

设置为全0。极化码编码为

G_N为极化码生成矩阵。Preferably, the transmitting end performs polar code encoding on the synchronization parameters; specifically, when performing polar code encoding on the synchronization parameters, the input sequence of the polar code encoder is:

Bits u ₁ to u _N are sent on the 1st to Nth bit channels in turn, and the set of polar code non-fixed bit channel sequence numbers is

M is a positive integer, and the set of fixed-bit channel sequence numbers is denoted as A ^c . The elements in the set A satisfy a _i <a _j when 1≤i<j≤M. The non-fixed bit sequence is denoted as

The polar code fixed bits are known at both ends of the transmission and reception, and the fixed bit sequence

Set to all 0s. Polar codes are encoded as

_GN is the polar code generator matrix.

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 a combination of multiple groups of preset signal start times, modulation center frequencies and channel phases, perform timing sampling, frequency offset correction and phase correction processing on the received extended synchronization signal, and obtain P' codes after demodulation word reception sequence; wherein, P' is the number of combinations of signal start time, modulation center frequency and channel phase, and each code word reception sequence corresponds to a set of parameters including signal start time, modulation center frequency and channel phase;

其中l＝1,2,...,P′，M₁、M₂、M₃均为正整数。需要说明的是信号起始时间、调制中心频率和信道相位的组合数量足够大，能够覆盖可能的起始时间、调制中心频率和信道相位。Specifically, M ₁ values are set for the signal start time, M ₂ values are set for the modulation center frequency, and M ₃ values are set for the channel phase. There are ₃ values P′=M ₁ M ₂ M in total Value combination, for each value combination, the received signal is sampled according to the signal start time, and the frequency offset correction is performed according to the modulation center frequency, and the phase correction is performed according to the channel phase, and a correction signal is obtained. sequence, and then demodulate to obtain a codeword received sequence, denoted as

Wherein l=1,2,...,P', and M ₁ , M ₂ , and M ₃ are 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.

且这4路输出信号的起始抽样点依次记为r₁，r₂，r₃，r₄，由于采样率是符号速率的8倍，接收端需进行8倍下采样，故

其中，l∈[1,4]，w_i＝r_(i-1)×8+l。对所得的4路抽样输出信号

分别进行频偏矫正，其中，每一个输出信号

l∈[1,4]分别进行f₁，f₂，f₃，f₄四种频偏矫正，一共输出16路信号。对输出的16路信号，分别进行4种相位偏移矫正，一共输出M₁M₂M₃＝64路信号。然后，对输出的64路信号

的每一路信号均进行补零操作，使补零之后信号长度为发送端母码的长度128，输出64路补零之后的信号，记为

将信号

采用BPSK算法进行解调，得到64个码字接收序列。In an optional embodiment 2, first, M ₁ =4 values are set for the signal start time; M ₂ =4 values are set for the modulation center frequency, which are respectively denoted as f ₁ , f ₂ , f ₃ , f ₄ ; M ₃ =4 values are set for the channel phase, which are respectively denoted as θ ₁ , θ ₂ , θ ₃ , and θ ₄ . The received signal is sampled according to the preset signal start time, and the length of each sampled signal is N _p = 110, then 4 sampled output signals can be obtained

And the starting sampling points of these four output signals are recorded as r ₁ , r ₂ , r ₃ , and r ₄ in turn. Since the sampling rate is 8 times the symbol rate, the receiver needs to downsample 8 times, so

Wherein, l∈[1,4], w _i =r _(i-1)×8+l . For the obtained 4-channel sampling output signal

Perform frequency offset correction separately, where each output signal

l∈[1,4] performs four frequency offset corrections of f ₁ , f ₂ , f ₃ and f ₄ respectively, and outputs 16 signals in total. For the output 16-channel signals, 4 kinds of phase offset corrections are respectively performed, and a total of M ₁ M ₂ M ₃ =64-channel signals are output. Then, for the output 64 signals

The zero-filling operation is performed on each channel of the signal, so that the length of the signal after zero-filling is 128, the length of the mother code of the transmitting end, and the 64-channel signal after zero-filling is output, denoted as

will signal

BPSK algorithm is used for demodulation, and 64 codeword reception sequences are obtained.

S22. The multi-codeword reception sequence SCL decoder is used to simultaneously decode each P codeword reception sequence in the P' codeword reception sequences to obtain P'/P decoding results and their corresponding codeword receptions sequence; for the obtained P′/P decoding results, the decoding result with the largest likelihood probability is selected as the optimal decoding codeword according to the principle of maximum likelihood, where P is a positive integer smaller than P′, and P′ /P is an integer.

Specifically, in an optional embodiment 3, the value of P' is 64, the value of P is 8, and the value of L is 8. In step S22, a method for simultaneously decoding P codeword reception sequences in P' codeword reception sequences by using a multi-codeword reception sequence SCL decoder, includes the following steps:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N，则转至步骤S223；若当前译码比特的索引序号i大于N，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为极化码码长，i为正整数；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 ;

令i＝i+1，返回步骤S221；其中，S_l表示译码器列表中第l条路径所对应的码字接收序列为

S_l的初始取值为l，

表示译码器列表中第l条路径对应的码字接收序列的第一个比特u₁的判决值，u₁是固定比特，

的取值均为已知的固定比特u₁的取值；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;

将每条路径

l＝1,2,...,L′扩展为

l＝1,2,...,L′，令i＝i+1，返回步骤S221；其中，

表示译码器列表中第l条路径对应的码字接收序列

的判决值，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且

的取值为已知的固定比特u_i的取值；S224: Denote the number of current paths in the decoder list as L', and the lth (l=1, 2, . . . , L') path is

each path

l=1,2,...,L' expands to

l=1,2,...,L', 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 ;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；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;

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。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.

获得译码码字，通过译码码字对应路径上记录的S_l获得译码码字对应的码字接收序列。此时，接收端判断最优译码码字是否存在且满足CRC校验，若存在且满足CRC校验，则最优译码码字有效。In an optional embodiment 4, the aforementioned transmitting end may also concatenate CRC encoding before polar code encoding, and perform CRC concatenated polar code encoding on the synchronization parameter; at this time, the method described in step S22 is the same as the optional Compared with the method described in Embodiment 3, step S226 described in Optional Embodiment 3 is modified to: output from L paths a decision sequence corresponding to a path that satisfies the CRC check and has the largest path metric value

_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. At this time, the receiving end judges whether the optimal decoding codeword exists and satisfies the CRC check, and if it exists and satisfies the CRC check, the optimal decoding codeword is valid.

In an optional embodiment 5, the sending end concatenates the verification code and the polar code, and performs the verification and concatenated polar code encoding on the synchronization parameter. Specifically, the verification code and the polar code are combined Concatenation can significantly improve the error correction performance of polar codes. This concatenated code is called a check concatenated polar code. The basic principle of the check concatenated polar code can be found in the paper Tao Wang, Daiming Qu, and Tao Jiang, "Parity-Check-Concatenated Polar Codes," IEEE Communications Letters, vol. 20, no. 12, pp. 2342-2345, Dec. 2016; In the check equation for checking the outer code of concatenated polar codes, the information bits For the selection method of the sum check bits, see the patent "An Error Correction Coding Method for Concatenating Polar Codes and Multi-bit Parity Check Codes" (Patent No.: CN201510995761.X). At this time, in step S22, the method of simultaneously decoding the P codeword reception sequences in the P' codeword reception sequences using the multi-codeword reception sequence SCL decoder is the same as the method described in the optional embodiment 3. Compared, the difference is:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N，则转至步骤S223；若当前译码比特的索引序号i大于N，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为校验级联极化码码长，i为正整数；Step S221 is modified as: receiving sequence for 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 the check concatenated polar code, i is a positive integer;

在u_i处分别取值0和1，获得2L′条备选路径

和

其中，l＝1,2,...,L′，路径

和

均对应接收序列

且路径

和

的路径度量值分别为

和

和

分别表示长度为N的极化码第i个比特信道输出为

时输入分别为0、1的转移概率；判断2L′是否小于等于L，若是，保留2L′条路径；若否，则保留其中L条度量值最大的路径；并令i＝i+1，返回步骤S221；Step S225 is modified as: if u _i is an information bit, the sequence in each path is

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

When inputting the transition probabilities of 0 and 1 respectively; judge whether 2L' is less than or equal to L, if so, keep 2L'paths; if not, keep the L paths with the largest metric value; and let i=i+1, return Step S221;

扩展为

令i＝i+1，返回步骤S221；其中，序列

中的元素

表示译码器列表中第l条路径在u_i处的判决值，并且其中

的取值根据u_i所在校验方程和该方程中信息比特在第l条路径上已判决的结果校验得到。If u _i is the check bit, then each path will be

expands to

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

elements in

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

The value of u _i is obtained by checking the check equation where u i is located and the result of the decision of the information bits in the equation on the lth path.

中的最后一个比特u^N为固定比特；此时，步骤S22中采用多码字接收序列SCL译码器对P′个码字接收序列中的P个码字接收序列同时进行译码的方法，与可选实施例3中所述的方法相比，区别在于：In an optional embodiment 6, when the transmitting end performs polar code encoding on the synchronization parameters, the sequence input to the polar code encoder is

The last bit u ^N in is a fixed bit; at this time, in step S22, a method of simultaneously decoding the P codeword reception sequences in the P' codeword reception sequences is performed by the multi-codeword reception sequence SCL decoder, Compared with the method described in alternative embodiment 3, the difference is:

若当前译码比特的索引序号i等于其初始值1，则转至S222；若当前译码比特的索引序号i大于1小于等于N-1，则转至步骤S223；若当前译码比特的索引序号i大于N-1，则转至步骤S226；其中，P≤L，L为预设SCL译码算法的最大路径数量，码字接收序列由极化码组成，N为极化码码长，i为正整数。通过使输入极化码编码器的序列

的最后一个比特u^N为固定比特，并在译码过程中跳过最后一个比特u^N，载波相位的取值只需要在0到π之间，能够减少一半的译码，大大提高了译码效率。Step S221 is modified as: receiving sequence for 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-1, go to step S223; if the index of the current decoded bit is If the serial number i is greater than N-1, 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 length of polar codes, i is a positive integer. By making the input polar code encoder sequence

The last bit u ^N is a fixed bit, and the last bit u ^N is skipped during the decoding process. The value of the carrier phase only needs to be between 0 and π, which can reduce half of the decoding and greatly improve the decoding process. efficiency.

其中，N表示极化码码长，向量

表示极化码码字，c_i(i＝1,2,...,N)表示第i个编码比特，向量

由两个子向量u_A＝(u_i,i∈A)和

组成，集合

称为极化码的非固定比特索引集合，集合

为A的补集，称为极化码的固定比特索引集合。极化码编码时，子向量u_A设定为信息比特序列，子向量

设定为接收端已知的固定比特序列，一般设定为全0序列。根据u_A和

确定向量

并编码得到极化码码字

It should be noted that polar codes are a class of linear block codes, and their coding formula is

Among them, N represents the polar code length, and the vector

represents the polar code word, ci ( _i =1,2,...,N) represents the ith coded bit, the vector

By two sub-vectors u _A = (u _i , i∈A) and

composition, collection

A set of non-fixed bit indices called polar codes, the set

is the complement of A, which is called the fixed bit index set of polar codes. In polar code encoding, the sub-vector u _A is set as the information bit sequence, and the sub-vector

It is set to a fixed bit sequence known to the receiving end, and is generally set to an all-zero sequence. According to u _A and

determine vector

And encode to get polar code word

Through the above method, in the extended synchronization signal, it is no longer necessary to provide the receiver with the signal start time, modulation center frequency and channel phase of the transmitter. The extended synchronization signal is received on the combination, the obtained synchronization code word is decoded after demodulation, and the validity of the obtained decoding result is further checked to determine whether the current combination corresponds to the start time, modulation center frequency and The channel phase can be further calculated to obtain the start time, modulation center frequency and channel phase of the subsequent data signal, so as to realize the communication synchronization between the receiver and the sender, which greatly reduces the overhead and saves a lot of spectrum resources.

Preferably, the method for judging whether the optimal decoding codeword is valid, comprises:

并计算映射序列

与最优译码码字对应的码字接收序列x之间的距离d；具体的，最优译码码字是一个长度为N的0、1序列，在译码正确的情况下，译码码字与编码码字相同。将最优译码码字映射为双极性序列，得到映射序列

其中，在一种可选实施例7中，译码码字中的比特0被映射为+1，译码码字中的比特1被映射为-1；映射序列

与最优译码码字对应的码字接收序列x之间的距离具体为欧式距离，且距离

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 codeword; specifically, the optimally decoded codeword is a sequence of 0s and 1s of length N. In the case of correct decoding, the decoding The codeword is the same as the encoded codeword. Map the optimal decoded codewords into bipolar sequences to get the mapping sequence

Wherein, in an optional embodiment 7, bit 0 in the decoded codeword is mapped to +1, and bit 1 in the decoded codeword is mapped to -1; the mapping sequence

The distance between the codeword received sequences x corresponding to the optimal decoding codeword is specifically the Euclidean distance, and the distance

以及所得距离d，判断最优译码码字是否为有效译码码字。According to the UER requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

and the obtained distance d to determine whether the optimal decoded codeword is a valid decoded codeword.

以及所得距离d，判断最优译码码字是否为有效译码码字的方法，包括：In an optional implementation manner, according to the UER requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

And the obtained distance d, the method for judging whether the optimal decoding codeword is an effective decoding codeword, including:

1) obtaining the distance between the codeword receiving sequence x corresponding to the optimal decoding codeword in all bipolar sequences of length N is less than the bipolar sequence number Q of the distance d;

中，计算满足

的双极性序列的个数Q。通过对上式进行分析，记

为所有长度为N的双极性序列中与最接近最优译码码字对应的码字接收序列x的双极性序列，上述问题可以有效转换为，在所有双极性序列

中计算满足

的双极性序列的个数，由于

故上述问题可以进一步转化成，在所有双极性序列

中，计算满足

的双极性序列的个数；并且可以进一步转换为，在所有双极性序列

中，计算满足

的双极性序列的个数Q，其中，

表示序列

和

不相同的元素的序号的集合，

表示双极性序列

和双极性序列

不相同的元素的序号的集合。由于

是常数，记

求解个数Q的问题进一步可转换为，在所有双极性序列

中，计算满足

的双极性序列的个数；综上，最终求解个数Q的问题可转换为在序列x中所有元素的序号集合A＝{1,2,…,N}的子集S中，计算满足

的子集的个数，其中，子集S包括空集和全集。In this embodiment, the values of the elements in the bipolar sequence are all +1 or -1; in all bipolar sequences

, the calculation satisfies

The number Q of bipolar sequences of . By analyzing the above formula, we can write

The bipolar sequence of the received sequence x for the codeword corresponding to the closest optimal decoding codeword in all bipolar sequences of length N, the above problem can be effectively transformed into, in all bipolar sequences

Computational Satisfaction

the number of bipolar sequences, since

Therefore, the above problem can be further transformed into, in all bipolar sequences

, the calculation satisfies

the number of bipolar sequences; and can be further converted to, in all bipolar sequences

, the calculation satisfies

The number of bipolar sequences Q, where,

Representation sequence

and

a collection of ordinal numbers of elements that are not identical,

represents a bipolar sequence

and bipolar sequences

A collection of ordinal numbers of elements that are not identical. because

is a constant, remember

The problem of solving the number Q can be further transformed into, in all bipolar sequences

, the calculation satisfies

the number of bipolar sequences of

The number of subsets of , where the subset S includes the empty set and the complete set.

Based on the above inference, in the embodiment of the present invention, the number Q of bipolar sequences whose distances from all bipolar sequences of length N and sequence x are less than the distance d is obtained, specifically including:

具体的，双极性序列

的元素

的获取方式为：若x_g≥0，则

否则，

其中，g∈{1,2,…,N}。1.1) Obtain the bipolar sequence x=[x 1 ,x 2 ,...,x N ] that is closest to the codeword received sequence x=[x ₁ ,x ₂ ,...,x _N ] in all bipolar sequences of length N

Specifically, bipolar sequences

Elements

The acquisition method is: if x _g ≥ 0, then

otherwise,

where g∈{1,2,…,N}.

与映射序列

进行比较，以得到两个序列中不相同的元素的序号集合

1.2) The bipolar sequence

with mapping sequence

Compare to get the ordinal sets of elements that are not identical in the two sequences

从序列x中筛选出相应的元素，并计算所筛选元素的绝对值之和，得到常数

1.3) Set according to the serial number

Filter out the corresponding elements from the sequence x, and calculate the sum of the absolute values of the filtered elements to get a constant

的子集个数Q^*，确定为所有长度为N的双极性序列中与序列x之间的距离小于距离d的双极性序列个数Q；其中，S为序号集合A的子集；1.4) Obtain the sequence number set A={1,2,...,N} of all elements in the sequence x, and set all subsets of the sequence number set A to satisfy

The number of subsets Q ^* of , is determined as the number Q of bipolar sequences whose distance from the sequence x is less than the distance d in all bipolar sequences of length N; wherein, S is a subset of the sequence number set A;

记为子集S′的筛选和；统计子集的筛选和在各子区间的分布情况，得到分布序列B_n＝[B_n,0,B_n,1,…,B_n,M+1]；根据分布序列B_n计算子集个数Q^*为：Specifically, the method for obtaining the number of subsets Q ^* is as follows: divide the interval [0, C] into M equal parts, so as to obtain M+2 sub-intervals within the real number range; For each subset S' of A, filter elements from the sequence x according to the subset S', and calculate the sum of the absolute values of the filtered elements

Denoted as the screening sum of subset S'; count the screening and distribution of subsets in each sub-interval, and obtain the distribution sequence B _n =[B _n,0 ,B _n,1 ,...,B _n,M+1 ] ; Calculate the number of subsets Q ^* according to the distribution sequence B _n as:

根据分布序列A_n计算分布序列B_n为：Among them, n∈{1,2,...,N}; and the method of obtaining the distribution sequence B _n is as follows: taking the absolute value of each element in the sequence x to obtain the sequence x ^* =[|x ₁ |,|x ₂ | ,...,|x _N |]; the distribution of each element in each sub-interval in the statistical sequence x ^* is obtained, so as to obtain the distribution sequence A ^* =[a ₀ ,a ₁ ,...,a _M+1 ]; specifically , a ₀ =0; for 1≤m≤M, a _m represents the number of elements in the sequence x ^* whose value is greater than or equal to (m-1)C/M and less than mC/M; a _M+1 represents The number of elements whose value is greater than or equal to C in the elements of the sequence x ^* ; define the distribution sequence A _n =[A _n,0 ,A _n,1 ,...,A _n,M+1 ], and according to the distribution sequence A ^* Calculate the distribution sequence A _n , specifically: if n=1, then A ₁ =A ^* ; if 1<n≤N, 0≤m≤M, and m=nm′, m′ is an integer, then A _n,m =A _1,m' ; if 1<n≤N, 0≤m≤M, and m≠nm', then A _n,m =0; if 1<n≤N, and m=M+1, then

According to the distribution sequence A _n , the distribution sequence B _n is calculated as:

Among them, ◆ means to convolve the two sequences and limit the maximum element sequence number of the result sequence to M+1; specifically, to calculate [r ₀ ,r ₁ ,...,r _M+1 ]=[p ₀ ,p ₁ ,...,p _M+1 ]◆[q ₀ ,q ₁ ,...,q _M+1 ] is an example to illustrate the calculation process. Specifically, the sequence [p ₀ ,p ₁ ,...,p _M+1 ] and [q ₀ ,q ₁ ,...,q _M+1 ] are subjected to convolution operation, and the result sequence is obtained as [v ₀ ,v ₁ ,...,v _2M+2 ]=[p ₀ ,p ₁ ,...,p _M+1 ]*[q ₀ ,q ₁ ,...,q _M+1 ], where * Represents a convolution operation; the maximum element number of the resulting sequence is limited to M+1, such that

2) Calculate the expected undetectable error rate of the optimal decoding codeword according to the number Q, and denote it as UER _e ;

其中，R为最优译码码字中冗余比特的个数，Q为所有长度为N的双极性序列中与序列x之间的距离小于距离d的双极性序列个数。Specifically, the expected undetectable error rate

Among them, R is the number of redundant bits in the optimal decoding codeword, and Q is the number of bipolar sequences whose distance from the sequence x is less than the distance d in all bipolar sequences of length N.

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

Specifically, by counting the number Q of bipolar sequences whose distance from the sequence x is less than the distance d in all bipolar sequences of length N, the closeness of the decoded codeword to the sequence x can be obtained, thereby obtaining the decoding The probability that a codeword is a valid decoded codeword.

以及所得距离d，判断最优译码码字是否为有效译码码字的方法，包括：In another optional embodiment, according to the UER requirements of the system, the codeword receiving sequence x corresponding to the optimal decoding codeword, the mapping sequence

And the obtained distance d, the method for judging whether the optimal decoding codeword is an effective decoding codeword, including:

1) Obtain the distance between the received sequences of codewords corresponding to the optimal decoding codewords in all bipolar sequences of length N whose distances are less than or equal to the number Q of bipolar sequences of the distance d; wherein, N is the most Optimal decoding codeword length;

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

3) 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;

R为最优译码码字中冗余比特的个数。where the expected undetectable error rate

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

Through the above method, the dependence on error detection coding is avoided, the resource overhead of transmitting error detection bits can be reduced, the coding efficiency and error correction performance can be effectively improved, and the limitation of the number of error detection bits on the UER control capability can be eliminated. Practical system UER requires flexible implementation of control over decoding undetectable error rate.

The invention provides a communication synchronization method. In the whole process, the extended synchronization signal does not need to provide the signal start time, modulation center frequency and channel phase information of the sender, and the control information of the sender does not need to be agreed in advance by the receiver and sender. , the corresponding synchronization parameters can be changed according to the communication mode, and flexible communication can be realized on the premise of ensuring that the 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 starting time, modulation center frequency and channel phase of the subsequent data signal to obtain the data sent by the transmitting end.

In a second aspect, the present invention provides a sending module, including an encoding unit and a modulation unit;

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

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

The synchronization parameters include parameter information of the demodulated and decoded data signals, and 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.

In a third aspect, the present invention provides a receiving module, including 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 code word and send it to the decoding unit;

The decoding unit is used for decoding the received synchronization codeword, and selects the optimal decoding codeword from the decoding result, and sends it to the judgment unit;

The judgment unit is used to judge whether the received optimal decoding codeword is valid. If 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. , extract the synchronization parameters in the optimal decoding codeword, and send the synchronization parameters and the start time, modulation center frequency and channel phase of the extended synchronization signal to the calculation unit;

The calculation unit is used to calculate 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.

In a fourth aspect, the present invention provides a communication synchronization system, including the sending module proposed in the second aspect of the present invention and the receiving module proposed in the third aspect of the present invention; the sending module sends a signal to the receiving module.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection 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

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

The strip path is marked as

1,2, P; 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, recording the number of the current paths in the decoder list as L', the first path as

1,2,. 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

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

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.

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

And calculating a mapping sequence

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 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.

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

And calculating a mapping sequence

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 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.

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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