CN105991502A - Method and device for receiving preambles - Google Patents

Abstract

The invention provides a method and a device for receiving a preamble, in view of at least one time domain symbol with a predetermined three-section time domain structure. The method and the device are characterized in that a preliminary timing synchronization mode comprises: by using a unique processing relationship and/or modulation relationship between the predetermined three-section time domain structures, delayed slip autocorrelation is carried out to acquire one group or multiple groups of cumulative correlation values; based on the one group or multiple groups of cumulative correlation values, after delay relationship matching and/or unique predetermined mathematical operation are/is carried out, an operation value is used for preliminary timing synchronization. As the method and the device are in view of at least one time domain symbol with a predetermined three-section structure, timing synchronization is carried out by using the delay relationship matching and/or the predetermined mathematical operation based on the three-section relationship between multiple time domain signals, the performance can be enhanced maximally, the timing synchronization algorithm is universal, and the complexity is low.

Description

Method and device for receiving preamble symbol

Technical Field

The invention belongs to the field of broadcast communication, and particularly relates to a method and a corresponding device for receiving a preamble symbol.

Background

At present, a method for implementing time synchronization between a transmitting end and a receiving end in an OFDM system is basically implemented based on preamble symbols. The preamble symbol is a symbol sequence known to both the transmitting end and the receiving end of the OFDM system, the preamble symbol marks the beginning of a physical frame (named as P1 symbol), only one P1 symbol or a plurality of P1 symbols occur consecutively in each physical frame, and the uses of the P1 symbol include:

1) enabling a receiving end to quickly detect whether a signal transmitted in a channel is an expected received signal;

2) providing basic transmission parameters (such as FFT point number, frame type information and the like) to enable a receiving end to carry out subsequent receiving processing;

3) detecting initial carrier frequency deviation and timing error for achieving frequency and timing synchronization after compensation;

4) emergency alerts or broadcast system wake-up.

Generally, the preamble symbol includes a physical layer Format Control part (PHY Format Control, or PFC) and a physical layer Content Control part (PHY Content Control, or PCC), and the preamble symbol of the DVB _ T2 system includes P1 and P2, which are used for transmitting signaling information or further for transmitting frame Format parameters. However, in the prior art, for the receiving method of the preamble symbol, it is considered that the plurality of transmitted preamble symbols transmit the required signaling to adapt to the system requirement, so the receiving method of the receiving end has low universality, and the algorithm complexity is often high in the timing synchronization process, and the transmission performance of the system is low.

Disclosure of Invention

The invention solves the problem that the receiving method of the leading symbol and the device in the prior art consider that a plurality of leading symbols are sent to transmit required signaling to adapt to the system requirement, so that the receiving method of the receiving end has low universality, the algorithm complexity is higher in the timing synchronization process, and the transmission performance of the system is lower.

In order to solve the above problem, an embodiment of the present invention provides a method for receiving a preamble symbol, where for at least one time domain symbol having a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure, the method includes the following steps: processing the physical frame to obtain a baseband signal and judging whether a preamble symbol expected to be received exists in the baseband signal; determining the position of the received preamble symbol in a physical frame; and decoding the signaling information carried by the preamble symbol when the signaling information exists, wherein a preliminary timing synchronization mode is included in the step of judging whether the preamble symbol expected to be received exists in the baseband signal, and the preliminary timing synchronization mode comprises the following steps: carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and performing delay relation matching and/or specific predetermined mathematical operation based on one or more groups of accumulated correlation values, using the operation values for initial timing synchronization, preliminarily determining the position of the preamble symbol in the physical frame, and when the preamble symbol comprises a plurality of three-segment structures, respectively obtaining three accumulated correlation values, namely U, between a third part C and a first part A, between the first part A and a second part B, and between the third part C and the second part B in the plurality of groups of three-segment structures_ca'(n)，U_cb'(n)，U_ab' (n) or at least two of them, performing delay relationship matching and/or a predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation values to obtain final operation values, and using the final operation values for initial synchronization.

Optionally, it is assumed that K time domain symbols respectively have a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure, and when the K time domain symbols are arranged as a first C-a-B and subsequent K-1B-C-a, at least one or more of the K time domain symbols having the predetermined three-segment time domain structures are used to obtain an accumulated correlation value

Will be provided withOne or more of the first and second delay values are subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain a first calculation value U_ca(n) the delay matching relationship comprises all or part of:

$U_{\mathrm{ca}}^1(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+{2\mathrm{Len}}_B+{\mathrm{Len}}_C)),$

$U_{\mathrm{ca}}^2(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ca}}^j(n-(K-j)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{ca}}^K\left(n\right)$

will be provided withOne or more of the first and second delay values are subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain a second calculation value U_cb-ab(n) the delay matching relationship comprises all or part of:

$U_{\mathrm{cb}}^1(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+{2\mathrm{Len}}_B)),$

$U_{\mathrm{ab}}^2(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ab}}^j(n-(K-j)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{ab}}^K\left(n\right).$

will be provided withOne or more of the first and second delay values are subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain a third calculation value U_ab-cb(n) of (a). The delay matching relationship comprises all or part of the following:

$U_{\mathrm{ab}}^1(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-\left({2\mathrm{Len}}_B\right)),$

$U_{\mathrm{cb}}^2(n-(K-2)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{cb}}^j(n-(K-j)\·(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{cb}}^K\left(n\right),$

finally, based on the first final operation value U_ca(n) and a second final calculated value U_cb-ab(n) and a third final calculated value U_ab-cbAnd (n) performing delay matching and performing specific operation on one or more of the delay elements, wherein the delay matching relationship comprises all or part of the following:

U_ca(n)，U_cb-ab(n),U_ab-cb(n-N_A)。

optionally, wherein the accumulated correlation value is obtained by using any one or at least two of K time domain symbols having a predetermined three-segment time domain structure.

Optionally, in at least one time domain symbol having a predetermined three-segment time domain structure, a first time domain symbol has a three-segment structure of prefix-body-suffix type CAB, and a subsequent time domain symbol has a three-segment structure of prefix-body type BCA, and the length of the first part is set to N_ALet the length of the second part be Len_BLet the length of the third portion be Len_CThe serial number of a first sampling point of the prefix-body-suffix type three-section structure CAB, which is selected from the beginning of the second part B and corresponds to the first part A, is set to be N1_1, and the serial number of a second sampling point of the prefix-body-suffix type three-section structure BCA, which is selected from the beginning of the second part B and corresponds to the first part A, is set to be N1_2, so that the condition that the serial numbers meet the requirements that the serial numbers of the first sampling points ofThe formula is that N1_1+ N1_2 is 2N_A-(Len_B+Len_c) And N1_1+ Len_B＝N_A。

Optionally, the delay number used in the predetermined number of delay correlation processes is added or subtracted by one to form the self delay number and the respective added or subtracted self delay number, the added delay number and the subtracted delay number, the sliding delay autocorrelation is performed according to the three delay numbers, and then a correlation result is selected according to a predetermined selection rule.

Optionally, the method further comprises estimating a sampling frequency deviation based on the correlation result after selecting one correlation result according to a predetermined selected rule.

Optionally, after completing the preliminary timing synchronization of the preamble symbol, taking U_ca(n) obtaining a first angle from the angle of the maximum value in (n), calculating a first small deviation estimated value, and calculating the value of U_cb-ab(n) and U_ab-cbAnd (n) after conjugate multiplication, obtaining a second angle by taking the angle corresponding to the maximum value, calculating a second small deviation estimation value, and obtaining the small deviation estimation value based on the first small deviation estimation value and the second small deviation estimation value.

The embodiment of the present invention further provides a device for receiving a preamble symbol, which is used to receive at least one time domain symbol with a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure sent by a sending end, and is characterized in that the device includes: a reception judging unit which processes the physical frame to obtain a baseband signal and judges whether a preamble symbol expected to be received exists in the baseband signal; the positioning part determines the position of the received preamble symbol in the physical frame; and an analysis part for decoding the signaling information carried by the preamble symbol when the signaling information exists, wherein the receiving judgment part and/or the positioning part comprises a preliminary timing synchronization unit, and the preliminary timing synchronization unit is at least used for: carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and based on a groupOr after delay relation matching and/or specific preset mathematical operation are carried out on a plurality of groups of accumulated correlation values, the operation values are used for initial timing synchronization, the position of the preamble symbol in a physical frame is preliminarily determined, and when the preamble symbol comprises a plurality of three-section structures, three accumulated correlation values, namely U, between a third part C and a first part A, between the first part A and a second part B, and between the third part C and a second part B in the plurality of groups of three-section structures can be respectively obtained_ca'(n)，U_cb'(n)，U_ab' (n) or at least two of them, performing delay relationship matching and/or a predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation values to obtain final operation values, and using the final operation values for initial synchronization.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

according to the preamble symbol receiving method and the receiving device provided by the embodiment of the invention, as for at least one time domain symbol with a three-segment structure, timing synchronization is carried out by utilizing delay relationship matching and/or predetermined mathematical operation based on the three-segment relationship among a plurality of time domain symbols, the performance is improved to the maximum extent, and the timing synchronization algorithm is relatively universal and has low complexity.

Drawings

FIG. 1 is a schematic diagram of a time domain structure of a physical frame in an embodiment of the present invention;

fig. 2 is a schematic diagram of a physical frame structure including a format control part and a content control part in an embodiment of the present invention;

FIG. 3 is a schematic illustration of a first three-stage structure in an embodiment of the invention;

FIG. 4 is a schematic illustration of a second three-segment structure in an embodiment of the invention;

fig. 5 is a logic diagram of a timing synchronization manner of four time domain symbols in an embodiment of the present invention.

Detailed Description

The inventor finds that the preamble symbol receiving method and device in the prior art do not specifically describe and optimize the preamble symbols of a plurality of three-segment structures, particularly the first one is CAB, and the latter is all the BCA structure.

In view of the above problems, the inventors have studied and provided a timing synchronization method using delay relationship matching and/or predetermined mathematical operations based on a three-segment relationship between a plurality of time domain symbols, which improves performance to the maximum and is a general timing synchronization algorithm with low complexity.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

The sending end applicable to the method for receiving the preamble symbol of the invention needs to meet the predetermined three-segment structure rule, the sending end utilizes at least one time domain with the predetermined three-segment structure to transmit signaling information, and the time domain symbol can adopt any one of a first predetermined three-segment time domain structure (CAB) or a second predetermined three-segment time domain structure (BCA). The time domain structure that needs to be satisfied in the originating side is described below with reference to fig. 1 to 4.

Fig. 1 is a schematic time domain structure diagram of a physical frame in an embodiment of the present invention.

As shown in fig. 1, a physical frame transmitted by a transmitting end of the present embodiment includes a preamble symbol and a data area, respectively, where the preamble symbol is located before the data area.

The data area is used for transmitting data information such as TS packets or IP packets.

The preamble symbol is used for fast detection to determine whether the signal transmitted in the channel is a signal expected to be received, and provides basic transmission parameters (such as FFT point number, frame type information, etc.), so that the receiving end can perform subsequent receiving processing; detecting initial carrier frequency deviation and timing error for achieving frequency and timing synchronization after compensation; emergency broadcast wakeup, etc.

Fig. 2 is a schematic diagram of a physical frame structure including a format control portion and a content control portion in an embodiment of the present invention.

As shown in fig. 2, the physical frame structure includes a preamble symbol and a data area, wherein the preamble symbol includes: the part PFC and the part PCC are controlled by the physical layer format. Of course, the preamble symbol according to the present invention is not limited to include the PFC part and the PCC part.

The format control part PFC consists of one or more time domain symbols (indicated by a hatched box in the figure), each OFDM time domain symbol being of the same size. In this embodiment, the time domain symbol is an OFDM symbol, and as can be seen from fig. 2, in this embodiment, the format control portion PFC of the sending end includes four time domain symbols.

FIG. 3 is a schematic illustration of a first three-stage structure in an embodiment of the invention; and FIG. 4 is a schematic illustration of a second three-stage structure in an embodiment of the present invention.

The format control part PFC of the preamble symbol includes at least one time domain symbol, and since the time domain symbol in this embodiment adopts the following first three-segment structure or second three-segment structure, the time domain symbol included in the preamble symbol may also be referred to as a three-segment structure time domain symbol. However, without limitation, the time domain symbols satisfying the above-mentioned preamble symbol may also adopt other structures other than the three-segment structure.

As can be seen from fig. 3 and fig. 4, in the first embodiment, the time domain symbol has the following three-stage structure: a first three-stage structure as in fig. 3: the method comprises the steps of firstly, generating a time domain main signal (A section), generating a prefix (C section) based on the rear part of the time domain main signal, and selecting a part of generated suffix (B section) in the prefix range based on the time domain main signal; a second three-stage structure as in fig. 4: the method comprises the steps of generating a time domain main signal (A section), generating a prefix (C section) based on the rear part of the time domain main signal, and selecting a part of generated prefix (B section) in a prefix range based on the time domain main signal.

A time domain body signal (denoted by a in the figure) is used as a first part, a part is taken out according to a preset acquisition rule at the tail end of the first part, the first part is processed and copied to the front part of the first part to generate a third part (denoted by C in the figure) to be used as a prefix, meanwhile, a part is taken out according to a preset acquisition rule from the rear part of the first part, the predetermined processing is processed and copied to the rear part of the first part or the predetermined processing is copied to the front part of the prefix to generate a second part (denoted by B in the figure) to be respectively used as a suffix or a super prefix, and therefore, a first three-segment structure (CAB structure) with B as a suffix and a second three-segment structure (BCA structure) with B as a super prefix shown in fig. 3 are respectively generated.

Based on the time domain symbol having the three-segment structure, the preamble symbol generated in this embodiment may include: a time domain symbol having a first three-segment structure; or a time domain symbol having a second three-segment structure; or a plurality of time domain symbols with the first three-segment structure and/or a plurality of time domain symbols with the second three-segment structure which are not arranged in sequence are freely combined. That is, the preamble symbol may only contain CAB or BCA, or may be several CABs or several BCAs, or may be any arbitrary combination of several CABs and several BCAs without limitation in number. It should be particularly noted that the preamble symbol of the present invention is not limited to a structure containing only C-a-B or B-C-a, but may also contain other time domain structures, such as a conventional CP structure.

The section A is obtained by performing IFFT transform of 2048 points, for example, on the basis of a certain frequency domain main body sequence, and the section C in the three-section structure is a direct copy of a part in the section A, while the section B is a modulation signal section of a part in the section A, and the data range of the section B does not exceed the data range of the section C, namely, the range of the part A selected to the modulation signal section B does not exceed the range of the part A intercepted as the prefix C. Preferably, the sum of the length of B and the length of C is the length of a.

Let N_ALet Len be the length of A_CIs the length of C, Len_BIs the length of the modulation signal segment B. Let the sampling point number of A be 0,1, … N_ALet N1 be the sample point number selected to be copied to the first portion a corresponding to the start of the second portion B of the modulation signal segment, and N2 be the sample point number selected to be copied to the first portion a corresponding to the end of the second portion B of the modulation signal segment. Wherein,

N2＝N1+Len_B-1 (formula 1)

In general, the modulation applied to the second part B segment is modulation frequency offset, modulation M sequence or other sequences, etc., in this implementation, taking modulation frequency offset as an example, if P1_ a (t) is a time domain expression of a, the time domain expression of the first common preamble symbol is

$P_{C-A-B}\left(t\right)=\left\{\begin{array}{cc}P1\_A(t+(N_A-{\mathrm{Len}}_C)T)& 0\&le;t<{\mathrm{Len}}_{c}T\\ P1\_A(t-{\mathrm{Len}}_{C}T)& {\mathrm{Len}}_{C}T\&le;t<(N_A+{\mathrm{Len}}_C)T\\ P1\_A(t-({\mathrm{Len}}_C+N_A-N1)T)e^{j2\mathrm{\&pi;}{f}_{\mathrm{SH}}t}& (N_A+{\mathrm{Len}}_C)T\&le;t<(N_A+{\mathrm{Len}}_C+{\mathrm{Len}}_B)T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 2)

Wherein, the modulation frequency deviation value f_SHCan be selected as the frequency domain subcarrier interval corresponding to the time domain OFDM symbol, namely 1/N_AT, or 1/(Len)_B+Len_c) T where T is the sampling period, N_AIs the length of a time domain OFDM symbol, e.g., N_AIs 1024, take f_SH1/1024T, and the modulation frequency offset may be arbitrarily chosen for the initial phase. To sharpen the correlation peak, f_SHCan also be selected to be 1/(Len)_BT) or a value close to its value.

In the structure of B-C-A, the modulation frequency deviation value is just opposite to that of the structure of C-A-B, and the modulation can be arbitrarily selected as an initial phase.

$P_{B-C-A}\left(t\right)=\left\{\begin{array}{cc}P1\_A(t+\left(N1\right)T)e^{-j2\mathrm{\&pi;}{f}_{\mathrm{SH}}\left({t-\mathrm{Len}}_{C}T\right)}& 0\&le;t<{\mathrm{Len}}_{B}T\\ P1\_A(t-({\mathrm{Len}}_B-N_A+{\mathrm{Len}}_C)T)& {\mathrm{Len}}_{B}T\&le;t<({\mathrm{Len}}_B+{\mathrm{Len}}_C)T\\ P1\_A(t-({\mathrm{Len}}_B+{\mathrm{Len}}_C)T)& ({\mathrm{Len}}_B+{\mathrm{Len}}_C)T\&le;t<({\mathrm{Len}}_B+{\mathrm{Len}}_C+N_A)T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 3)

Setting the serial number of a first sampling point corresponding to the first part (A) and selecting the starting point of the second part (B) in the first three-segment structure (CAB) as N1_1, setting the serial number of a second sampling point corresponding to the first part (A) and selecting the starting point of the second part (B) in the second three-segment structure (BCA) as N1_2, wherein the serial numbers of the first sampling point N1_1 and the second sampling point N1_2 need to satisfy the following formula

N1_1+N1_2＝2N_A-(Len_B+Len_c) (formula 4)

The advantage of satisfying such a relationship is that the delay relationship of the same content from segment C to segment B in the C-A-B structure is the same as the delay relationship of the same content from segment B to segment A in the B-C-A structure, and the delay relationship of the same content from segment A to segment B in the C-A-B structure is the same as the delay relationship of the same content from segment B to segment C in the B-C-A structure, which is beneficial for the receiver implementation. And in the C-A-B structure and the B-C-A structure, if the modulation adopted for the B section is modulation frequency offset, the frequency offset values f of the two structures_SHBut just the opposite, facilitates the receiver implementation.

In addition, N1_1+ Len is usually taken_B＝N_A。

The symbol of C-A-B structure is represented by the symbol No. 1, and the symbol of B-C-A structure is represented by the symbol No. 2. Then, let P1_ A (t) be the time domain expression of A1, P2_ A (t) be the time domain expression of A2, and then the time domain expression of the C-A-B three-segment structure is

$P1\left(t\right)=\left\{\begin{array}{cc}P1\_A(t+(N_A-{\mathrm{Len}}_C)T)& 0\&le;t<{\mathrm{Len}}_{c}T\\ P1\_A(t-{\mathrm{Len}}_{C}T)& {\mathrm{Len}}_{C}T\&le;t<(N_A+{\mathrm{Len}}_C)T\\ P1\_A(t-({\mathrm{Len}}_C+N_A-N1\_1)T)e^{j2\mathrm{\&pi;}{f}_{\mathrm{SH}}t}& (N_A+{\mathrm{Len}}_C)T\&le;t<(N_A+{\mathrm{Len}}_C+{\mathrm{Len}}_B)T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 5)

The time domain expression of the three-section structure of B-C-A is as follows

$P2\left(t\right)=\left\{\begin{array}{cc}P2\_A(t+(N1\_2)T)e^{-j2\mathrm{\&pi;}{f}_{\mathrm{SH}}\left({t-\mathrm{Len}}_{C}T\right)}& 0\&le;t<{\mathrm{Len}}_{B}T\\ P2\_A(t-({\mathrm{Len}}_B-N_A+{\mathrm{Len}}_C)T)& {\mathrm{Len}}_{B}T\&le;t<({\mathrm{Len}}_B+{\mathrm{Len}}_C)T\\ P2\_A(t-({\mathrm{Len}}_B+{\mathrm{Len}}_C)T)& ({\mathrm{Len}}_B+{\mathrm{Len}}_C)T\&le;t<({\mathrm{Len}}_B+{\mathrm{Len}}_C+N_A)T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 6)

The first three-segment structure and the second three-segment structure which are arranged in sequence are not distinguished, and different leading symbols which are freely combined by a plurality of first three-segment structures and/or a plurality of second three-segment structures can be respectively formed according to different sequences. The time domain expression of a first preamble symbol, which is 1C-a-B and 1B-C-a in order, and the time domain expression of a second preamble symbol, which is 1B-C-a and 1C-a-B in order, are given below by way of example.

Then, the time domain expression of the first preamble symbol is:

(formula 7)

The time domain expression of the second preamble symbol is:

(formula 8)

Other combinations of C-A-B and B-C-A can be deduced according to the time domain expression of the first preamble symbol and the second preamble symbol, and repeated description is omitted here.

As in the above case, when the C-a-B structure and the B-C-a structure are cascaded, the problem of small bias estimation failure under a dangerous delay can be solved. When the critical delays cause the cancellation of the C and a segments, the CB segment of the first structure and the BC segment of the second structure can still be used for timing synchronization and estimation bias.

The number of at least one time domain symbol contained in the preamble symbol is set to transmit four symbols, and several preferred four time domain symbol structures are given below and are arranged in sequence as any one of the following structures:

(1) C-A-B, B-C-A, C-A-B, B-C-A; or

(2) C-A-B, B-C-A, B-C-A, B-C-A; or

(3) B-C-A, C-A-B, C-A-B, C-A-B; or

(4) C-A-B, B-C-A, C-A-B, C-A-B; or

(5) C-A-B, C-A-B, C-A-B, B-C-A; or

(6) C-A-B, C-A-B, C-A-B, C-A-B or

(7)C-A-B，C-A-B，B-C-A，B-C-A。

Among them, the structure of four time domain symbols, such as (1) C-A-B, B-C-A, maximizes the effect of concatenation. For example, (2) the structure of four time domain symbols, C-A-B, B-C-A, B-C-A, B-C-A, lengthens the guard interval of the subsequent symbol A portion, and typically the first symbol is a known signal, so C-A-B is used.

One preferred embodiment of a three-stage structure, N_A2048, let Len_CIs 520, Len_BWhere P1_ a (t) is the temporal body a expression, 504, N1_1 is 1544, N1_2 is 1528, it can be derived that the temporal expressions of C-a-B and B-C-a are the same

$P_{C-A-B}\left(t\right)=\left\{\begin{array}{cc}P1\_A(t+1528T)& 0\&le;t<520T\\ P1\_A(t-520T)& 520T\&le;t<2568T\\ P1\_A(t-1024T)e^{j2\mathrm{\&pi;}{f}_{\mathrm{SH}}t}& 2568T\&le;t<3072T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 9)

And

$P_{B-C-A}\left(t\right)=\left\{\begin{array}{cc}P1\_A(t+1528T)e^{-j2\mathrm{\&pi;}{f}_{\mathrm{SH}}(t-520T)}& 0\&le;t<504T\\ P1\_A(t+1024T)& 504T\&le;t<1024T\\ P1\_A(t-1024T)& 1024T\&le;t<3072T\\ 0& \mathrm{otherwise}\end{array}\right.$

(formula 10)

Further, f_SHCan be selected as 1/(1)024T) or 1/(2048T).

Further, the emergency broadcast system may be identified by selecting a different starting point for the second part B from the first part a, i.e. by selecting a different N1, or N1_1 and N1_2, by copying to the starting point of the B segment. A symbol of a three-segment structure such as C-a-B, N1_ 1-1544 identifies a general system, and N1_ 1-1528 identifies an emergency broadcast system. For another example, in the notation of the three-segment structure of B-C-a, N1_2 ═ 1528 identifies a general system, and N1_2 ═ 1544 identifies an emergency broadcast system.

The method for generating the preamble symbol of the transmitting end comprises the following steps:

the method comprises the steps of generating frequency domain subcarriers based on a frequency domain main body sequence, carrying out inverse Fourier transform (IFFT) on the frequency domain subcarriers to obtain a time domain main body signal A, and forming a time domain symbol with a three-section structure of C-A-B or B-C-A by the time domain main body signal A, so that a preamble symbol with at least one time domain symbol in the embodiment is formed.

The above description, with reference to fig. 1 to fig. 4, describes at least one time domain symbol with a predetermined three-segment structure in an applicable transmitting end for the preamble symbol receiving method of the present invention.

In this embodiment, the provided method for receiving a preamble symbol includes, for at least one time domain symbol having a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure, the following steps:

step S1: processing the physical frame to obtain a baseband signal and judging whether a preamble symbol expected to be received exists in the baseband signal;

step S2: determining the position of the received preamble symbol in a physical frame; and

step S3: and when the signaling information exists, the signaling information carried by the preamble symbol is solved.

Wherein, the step of judging whether the preamble symbol expected to be received exists in the baseband signal comprises a preliminary timing synchronization mode, and the preliminary timing synchronization mode comprises the following steps:

carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and

performing delay relation matching and/or specific predetermined mathematical operation based on one or more groups of accumulated correlation values, using the operation values for initial timing synchronization, preliminarily determining the positions of preamble symbols in a physical frame,

when the preamble symbol comprises a plurality of three-segment structures, three accumulated correlation values, namely U, between the third part C and the first part A, between the first part A and the second part B, and between the third part C and the second part B in the plurality of groups of three-segment structures can be obtained respectively_ca'(n)，U_cb'(n)，U_ab' (n) or at least two of them, performing delay relationship matching and/or a predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation values to obtain final operation values, and using the final operation values for initial synchronization.

The preliminary timing synchronization method for the time domain symbols with the first CAB structure and the subsequent BCA structure will be described below.

Wherein, the formula N1_1+ N1_2 ═ 2N is satisfied_A-(Len_B+Len_c) And N1_1+ Len_B＝N_A。

In particular, N_A2048, let Len_CIs 520, Len_B＝504,N1_1＝1544，N1_2＝1528,f_SH1/(2048T) for example.

When the preamble symbol has a time domain structure of C-A-B or B-C-A, the baseband signal is subjected to necessary inverse processing and/or signal demodulation and then is subjected to delay sliding autocorrelation by utilizing the processing relation and/or modulation relation specific to C-A-B and/or B-C-A to obtain 1 or more groups of accumulated correlation values, delay relation matching and/or specific mathematical operation are carried out on the basis of the one or more groups of accumulated correlation values, and then the operation value is used for initial timing synchronization, so that the position of the preamble symbol in a physical frame is preliminarily determined. For example, the formula of obtaining the accumulated correlation value by the delayed sliding autocorrelation is as follows:

U₁(n)＝r(n)r^*(n-N_A)

${U_1}^{\&prime;}\left(n\right)=\frac{1}{N_{\mathrm{CP}}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_1(n-k)$ (formula 11)

Can select the U pair₁' (n) normalizing the energy to obtain U_1s'(n)。

Namely, it is ${U_{1s}}^{\&prime;}\left(n\right)=\frac{{U_1}^{\&prime;}\left(n\right)}{0.5\underset{k=0}{\overset{N_{\mathrm{cp}}-1}{\mathrm{\&Sigma;}}}({\left|r(n-k)\right|}^2+{\left|r\left({n-k-N}_A\right)\right|}^2)}$ (formula 12)

Other methods of energy normalization are also possible, U₁The conjugation in (N) can also be performed by r (N), and r (N-N)_A) Conjugation is not taken.

In the structure of each C-A-B or B-C-A, three accumulated correlation values of CA, AB and CB based on the same content can be obtained respectively.

The same part of the section C and the section a is used for the sliding delay correlation, and it is noted that the above energy normalization step can be added, and is not described here again. Each 1C-A-B or B-C-A structure can give rise to trisThe correlation value is: u shape_ca'(n)，U_cb'(n)，U_cb'(n)

U₁(n)＝r(n)r^*(n-N_A)

(formula 13)

${U_{\mathrm{ca}}}^{\&prime;}\left(n\right)=\frac{1}{{\mathrm{Len}}_C}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_1(n-k)$

And performing sliding delay correlation by using the same part of the B section and the C section, which only modulates the frequency offset:

when the structure is C-A-B,

$U_2\left(n\right)=r\left(n\right)r^{*}(n-N_A-N_A+N1\_1)e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}=r\left(n\right)r^{*}({n-N}_A-{\mathrm{Len}}_B)e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}$

${U_{\mathrm{cb}}}^{\&prime;}\left(n\right)\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_2(n-k)$

(formula 14)

When the structure of B-C-A is shown,

$U_2\left(n\right)=r\left(n\right)r^{*}(n-(N1\_2-N_A+{\mathrm{Len}}_c+{\mathrm{Len}}_B))e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}=r\left(n\right)r^{*}\left(n-\left({\mathrm{Len}}_B\right)\right)e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}$

${U_{\mathrm{cb}}}^{\&prime;}\left(n\right)\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_2(n-k)$

(formula 15)

And B, performing sliding delay correlation by using the same part of the B section and the A section, which only modulates the frequency offset:

when the structure is C-A-B,

$U_3\left(n\right)=r\left(n\right)r^{*}({n-N}_A+N1\_1)e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}=r\left(n\right)r^{*}(n-{\mathrm{Len}}_B)e^{{-\mathrm{jnf}}_{\mathrm{SH}}T}$

${U_{\mathrm{ab}}}^{\&prime;}\left(n\right)\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_3(n-k)$

(formula 16)

When the structure of B-C-A is shown,

$U_3\left(n\right)=r\left(n\right)r^{*}(n-N1\_2-{\mathrm{Len}}_B-{\mathrm{Len}}_C)e^{-{\mathrm{jnf}}_{\mathrm{SH}}T}=r\left(n\right)r^{*}(n-N_A-{\mathrm{Len}}_B)e^{{-\mathrm{jnf}}_{\mathrm{SH}}T}$

${U_{\mathrm{ab}}}^{\&prime;}\left(n\right)\frac{1}{\mathrm{corr}\_\mathrm{len}}\underset{k=0}{\overset{N_{\mathrm{CP}}-1}{\mathrm{\&Sigma;}}}{U}_3(n-k)$

(formula 17)

Wherein corr _ len can take 1/f_SHT to avoid continuous wave interference, or Len_BSo that the peak is sharp.

When the preamble symbol comprises a plurality of time domain symbols and the time domain symbols all adopt a three-segment structure, a plurality of groups of three accumulated correlation values of CA, AB and CB can be obtained,namely U_ca'(n)，U_cb'(n)，U_ab' (n) using the U_ca'(n)，U_cb'(n)，U_ab' (n) obtaining a set of accumulated correlation values, performing delay relationship matching and/or mathematical operations based on one or more of the sets of values to obtain final operation values, and using the final operation values for initial synchronization.

For example, for the preferred K time domain symbols with three-segment structure, the arrangement is C-A-B, B-C-A, B-C-A, B-C-A, …, B-C-A, i.e. the first symbol is C-A-B structure, and the subsequent K-1 symbols are all B-C-A structure, so as to obtain the final product It should be noted that any one or at least two of K time domain symbols having a predetermined three-segment time domain structure may also be used to obtain an accumulated correlation value, and the present invention does not limit the number of the time domain symbols used, and may be used in all or in part.

Then can be combined withOne or more of them is subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain the final U_ca(n) of (a). Because they have the same phase value. Delay matching includes all or part of the following, for example:

$U_{\mathrm{cb}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+{2\mathrm{Len}}_B+{\mathrm{Len}}_C)),$

$U_{\mathrm{ca}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ca}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{ca}}^K\left(n\right)$

wherein, consider the example f_SH＝1/(2048T),N_A2048, let Len_CIs 520, Len_B504, i.e. (N)_A+Len_B+Len_C) 3072, soTo make phase adjustment, multiply by e^jπ。

Can be combined withOne or more of them is subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain the final U_cb-ab(n) of (a). Because they have the same phase value. Delay matching includes all or part of the following, examplesThe following were used:

$U_{\mathrm{cb}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+{2\mathrm{Len}}_B)),$

$U_{\mathrm{ab}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ab}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{ab}}^K\left(n\right).$

wherein, consider the example f_SH＝1/(2048T),N_A2048, let Len_CIs 520, Len_B504, i.e. (N)_A+Len_B+Len_C) 3072, soTo make phase adjustment, multiply by e^jπ。

Can be combined withOne or more of them is subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain the final U_ab-cb(n) of (a). Delay matching includes all or part of the following, for example:

$U_{\mathrm{ab}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-\left({2\mathrm{Len}}_B\right)),$

$U_{\mathrm{cb}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{cb}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

$U_{\mathrm{cb}}^K\left(n\right).$

wherein, consider the example f_SH＝1/(2048T),N_AIn the range of 2048 (parts by weight),let Len_CIs 520, Len_B504, i.e. (N)_A+Len_B+Len_C) 3072, soTo be multiplied by e^jπ.

Finally, based on U_ca(n) and U_cb-ab(n) and U_ab-cbAnd (n) performing delay matching and performing specific operation, wherein the delay matching comprises all or part of the following, for example:

U_ca(n)，U_cb-ab(n),U_ab-cb(n-N_A)

the initial timing synchronization is completed based on the operation result, and the specific digital operation may be absolute value addition. Such as taking the maximum position to complete initial timing synchronization.

It should be noted that, in the above embodiment, in consideration of the influence of the system sampling clock offset, the delay numbers of some of the delay correlators may be added or subtracted by one to form themselves and three delay numbers after adding or subtracting one, the sliding delay autocorrelation is performed according to the three delay numbers, and the most significant one of the correlation results is selected, so that the sampling frequency offset can be further estimated.

Fig. 5 is a logic diagram of a timing synchronization manner of four time domain symbols in an embodiment of the present invention.

In FIG. 5, A represents N_AB represents Len_BC represents Len_CFig. 5 also shows the logic diagram of a specific timing synchronization method, i.e., 4 time domain symbols for CAB-BCA, respectively.

It is particularly noted that, when the preamble symbol receiving method of the present invention completes the timing synchronization, U is taken_ca(n) obtaining a first angle from the angle of the maximum value in (n), thereby calculating a first estimated small deviation value, and calculating the U_cb-ab(n) and U_ab-cb(n) after conjugate multiplication, the angle corresponding to the maximum value is also takenAnd obtaining a second angle, thereby calculating a second small deviation estimated value. Based on the first and second small bias estimates, a small bias estimate may be derived, as noted in the portion of fig. 5 labeled FFO calculation.

Not shown in the drawings, an embodiment of the present invention further provides a receiving apparatus for a preamble symbol, configured to receive at least one time domain symbol with a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure sent by a sending end, where the receiving apparatus for a preamble symbol includes: a reception judging unit which processes the physical frame to obtain a baseband signal and judges whether a preamble symbol expected to be received exists in the baseband signal; the positioning part determines the position of the received preamble symbol in the physical frame; and an analysis unit configured to decode the signaling information carried by the preamble symbol when the signaling information exists.

Wherein, receiving judgement portion and/or location portion contain preliminary timing synchronization unit, and preliminary timing synchronization unit is used for at least:

carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and

performing delay relation matching and/or specific predetermined mathematical operation based on one or more groups of accumulated correlation values, using the operation values for initial timing synchronization, preliminarily determining the positions of preamble symbols in a physical frame,

when the preamble symbol comprises a plurality of three-segment structures, three accumulated correlation values, namely U, between the third part C and the first part A, between the first part A and the second part B, and between the third part C and the second part B in the plurality of groups of three-segment structures can be obtained respectively_ca'(n)，U_cb'(n)，U_ab' (n) or at least two of them, performing delay relationship matching and/or a predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation values to obtain final operation values, and using the final operation values for initial synchronization.

The preamble symbol generating device and the receiving device provided in this embodiment may respectively correspond to the preamble symbol generating method and the receiving method in the foregoing embodiments, so that the structure and technical elements in the device may be formed by corresponding conversion of the generating method, and are not described again here.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

Claims (8)

1. A method for receiving a preamble symbol is directed to at least one time domain symbol having a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure, and comprises the following steps:

processing a physical frame to obtain a baseband signal and judging whether a preamble symbol expected to be received exists in the baseband signal;

determining the position of the received preamble symbol in a physical frame; and

decoding the signaling information carried by the preamble symbol when the signaling information exists,

wherein, in the step of determining whether there is a preamble symbol expected to be received in the baseband signal, a preliminary timing synchronization mode is included, and the preliminary timing synchronization mode includes:

carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and

performing delay relation matching and/or specific predetermined mathematical operation based on one or more groups of accumulated correlation values, using the operation values for initial timing synchronization, preliminarily determining the positions of preamble symbols in a physical frame,

when the preamble symbol comprises a plurality of three-segment structures, three accumulated correlation values, namely U, between the third part C and the first part A, between the first part A and the second part B, and between the third part C and the second part B in the three-segment structures can be obtained respectively_ca'(n)，U_cb'(n)，U_ab' (n) or at least two of them, performing delay relationship matching and/or a predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation values to obtain final operation values, and using the final operation values for initial synchronization.

2. A preamble symbol receiving method as claimed in claim 1, wherein:

when K time domain symbols are arranged into a first C-A-B and subsequent K-1B-C-A, at least one or more of the K time domain symbols with the predetermined three-section time domain structure are used to obtain an accumulated correlation value

Will be provided withOne or more of the first and second delay values are subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain a first calculation value U_ca(n) the delay matching relationship comprises all or part of:

$U_{\mathrm{ca}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+2{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$

$U_{\mathrm{ca}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ca}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ca}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

will be provided withOne or more of them is subjected to delay relation matching and/or phase adjustment and then to addition or smoothingAll obtain a second calculation value U_cb-ab(n) the delay matching relationship comprises all or part of:

$U_{\mathrm{cb}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-(N_A+2{\mathrm{Len}}_B)),$

$U_{\mathrm{ab}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{ab}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{ab}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

will be provided withOne or more of the first and second delay values are subjected to delay relation matching and/or phase adjustment and then added or averaged to obtain a third calculation value U_ab-cb(n) of (a). The delay matching relationship comprises all or part of the following:

$U_{\mathrm{ab}}^1(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)-\left(2{\mathrm{Len}}_B\right)),$

$U_{\mathrm{cb}}^2(n-(K-2)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),....U_{\mathrm{cb}}^j(n-(K-j)\&CenterDot;(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C))$

$U_{\mathrm{cb}}^{K-1}(n-(N_A+{\mathrm{Len}}_B+{\mathrm{Len}}_C)),$ and

finally, based on the first final operation value U_ca(n) and a second final calculated value U_cb-ab(n) and a third final calculated value U_ab-cbAnd (n) performing delay matching and performing specific operation on one or more of the delay elements, wherein the delay matching relationship comprises all or part of the following:

U_ca(n)，U_cb-ab(n),U_ab-cb(n-N_A)。

3. a preamble symbol receiving method as claimed in claim 2, wherein:

and obtaining the accumulated correlation value by using any one or at least two of K time domain symbols with a preset three-segment time domain structure.

4. A preamble symbol receiving method as claimed in claim 1, wherein:

wherein, in the at least one time domain symbol having the predetermined three-segment time domain structure,

the first time domain symbol has a three-segment structure of prefix-body-suffix type CAB and the subsequent time domain symbol has a three-segment structure of prefix-body type BCA,

setting a length of the first portion to N_ASetting the length of the second part as Len_BSetting the length of the third portion to Len_CThe serial number of a first sampling point of the prefix-body-suffix type three-segment structure CAB, which is selected from the beginning of the second part B and corresponds to the first part A, is set to be N1_1, and the serial number of a second sampling point of the prefix-body-suffix type three-segment structure BCA, which is selected from the beginning of the second part B and corresponds to the first part A, is set to be N1_2, so that the following formula is satisfied:

N1_1+N1_2＝2N_A-(Len_B+Len_c) And N1_1+ Len_B＝N_A。

5. A preamble symbol receiving method as claimed in claim 1, wherein:

the delay number used in the delay correlation processing of the preset number is added and subtracted by one to form the self delay number and the self delay number, the added delay number and the subtracted delay number which are respectively added and subtracted, the sliding delay autocorrelation is implemented according to the three delay numbers, and then a correlation result is selected according to the preset selection rule.

6. A preamble symbol receiving method as claimed in claim 4, further comprising:

after selecting a correlation result with a predetermined selected rule, a sampling frequency deviation is estimated based on the correlation result.

7. A method of receiving preamble symbols according to claim 1,

after finishing the preliminary timing synchronization of the preamble symbol, taking U_ca(n) obtaining a first angle from the angle of the maximum value in (n), and calculating a first small deviation estimateEvaluating U, and then adding U_cb-ab(n) and U_ab-cb(n) after conjugate multiplication, taking the angle corresponding to the maximum value to obtain a second angle, thereby calculating a second small deviation estimated value,

and obtaining a small deviation estimated value based on the first small deviation estimated value and the second small deviation estimated value.

8. A receiving device of preamble symbols is used for receiving at least one time domain symbol with a first predetermined three-segment time domain structure or a second predetermined three-segment time domain structure sent by a sending end, and is characterized by comprising:

a reception determination unit configured to process a physical frame to obtain a baseband signal and determine whether a preamble symbol expected to be received exists in the baseband signal;

the positioning part determines the position of the received preamble symbol in the physical frame; and

an analysis unit for decoding the signaling information carried by the preamble symbol when the signaling information exists,

wherein, receiving judgement portion and/or location portion contain preliminary timing synchronization unit, and preliminary timing synchronization unit is used for at least:

carrying out necessary reverse processing and/or signal demodulation on a baseband signal by utilizing a processing relation and/or a modulation relation which are specific to a first preset three-section time domain structure and/or a second preset three-section time domain structure, and then carrying out delay sliding self-correlation to obtain one or more groups of accumulated correlation values; and

performing delay relation matching and/or specific predetermined mathematical operation based on one or more groups of accumulated correlation values, using the operation values for initial timing synchronization, preliminarily determining the positions of preamble symbols in a physical frame,

when the preamble symbol comprises a plurality of three-segment structures, three accumulated correlation values, namely U, between the third part C and the first part A, between the first part A and the second part B, and between the third part C and the second part B in the three-segment structures can be obtained respectively_ca'(n)，U_cb'(n)，U_ab' (n) any one or any at least two of which are subjected to delay relation matching and/or predetermined mathematical operation based on one or more of the plurality of sets of accumulated correlation valuesAnd calculating to obtain a final calculation value, and using the final calculation value for initial synchronization.