CN108234376B

CN108234376B - Wireless data communication method and device

Info

Publication number: CN108234376B
Application number: CN201711270239.0A
Authority: CN
Inventors: 陈力; 赵琮; 吴晓立; 丘聪; 陈世超; 丘家行
Original assignee: SHENZHEN RENERGY TECHNOLOGY CO LTD
Current assignee: SHENZHEN RENERGY TECHNOLOGY CO LTD
Priority date: 2017-12-05
Filing date: 2017-12-05
Publication date: 2021-08-13
Anticipated expiration: 2037-12-05
Also published as: CN108234376A

Abstract

The invention is suitable for the technical field of communication, and provides a wireless data communication method and a device, wherein the method comprises the following steps: generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises a coarse synchronization signal and a fine synchronization signal; modulating a digital signal to be transmitted to generate a modulated signal, and inserting a preamble symbol sequence set in front of the modulated signal to form a transmission signal; the method comprises the steps of carrying out coarse synchronization and fine synchronization processing on a received signal, obtaining timing deviation, carrier frequency deviation and carrier phase of the received signal, carrying out timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal, and carrying out carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase. According to the invention, coarse synchronization detection and further fine synchronization detection are carried out on the received signals based on Chirp, so that the method can effectively capture the signals under the working condition of low SNR.

Description

Wireless data communication method and device

Technical Field

The invention belongs to the technical field of communication, and particularly relates to a wireless data communication method and device.

Background

The wireless low-power-consumption wide area network is a long-distance wireless communication technology which is generated in order to meet the demand of the internet of things, and the communication technology requires that equipment has low receiving sensitivity and can work in a low-power-consumption and low-cost state.

According to shannon's theorem, reducing the communication service rate is the most direct and effective means for improving the receiving sensitivity, and when other overheads such as spreading and FEC are not considered, the service rate can be effectively reduced by reducing the physical layer symbol rate, but reducing the physical layer symbol rate excessively brings about a reduction in the effective bandwidth Bw of the signal, which may be limited by the electromagnetic spectrum supervision of the application environment and the carrier frequency deviation between the transceiver devices. In addition, the effective service rate can be continuously reduced through spread spectrum under the condition of not reducing the symbol rate of the physical layer of the system; however, spreading results in a reduction of the demodulation threshold SNR within the receiver system bandwidth, and the existing communication system cannot acquire signals quickly and effectively under the low SNR operating condition.

Disclosure of Invention

In view of this, embodiments of the present invention provide a wireless data communication method and apparatus, so as to solve the problem in the prior art that a signal cannot be captured quickly and effectively under a low SNR operating condition.

A first aspect of an embodiment of the present invention provides a wireless data communication method, including: the method comprises the steps of signal transmission and signal reception;

generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises a coarse synchronization signal and a fine synchronization signal;

modulating a digital signal to be transmitted to generate a modulated signal, and inserting a sequence set of preamble symbols in front of the modulated signal to form a transmission signal;

receiving a transmitting signal, and performing coarse synchronization and fine synchronization processing on the receiving signal to acquire a timing deviation, a carrier frequency deviation and a carrier phase of the receiving signal;

and performing timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal, and performing carrier recovery on the received signal subjected to the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase.

Optionally, the coarse synchronization signal includes one or more continuous forward chirp signals and reverse chirp signals; the fine synchronization signal comprises a synchronization signal with autocorrelation characteristics;

the coarse synchronization processing of the received signal comprises: multiplying the received linear frequency modulation pulse signal by a conjugate signal of a local reference signal, calculating a power spectrum of a multiplied product signal, and roughly estimating the carrier frequency deviation and the timing of a leading symbol starting boundary according to the maximum peak position of the power spectrum;

the fine synchronization processing of the received signal comprises: and performing coarse synchronization information compensation on the signal to be detected, performing correlation operation on the signal to be detected and a fine synchronization signal, determining the carrier frequency deviation and symbol timing of the received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to the phase information of an accumulated complex result corresponding to the effective energy output.

Optionally, the performing carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency offset and the carrier phase includes,

performing integral processing on the loop filter output signal according to the received carrier frequency deviation and the carrier phase to obtain an output phase;

performing phase compensation on the received signal according to the output phase, outputting the obtained phase compensation signal, and performing phase discrimination processing on the phase deviation of the phase-compensated signal to obtain the estimation of the phase difference;

and filtering the estimated value of the phase difference to obtain a loop filtering output signal.

Optionally, before modulating the digital signal to be transmitted, the method further includes: performing spread spectrum processing on a digital signal to be transmitted in a bit data redundancy mode;

after the timing recovery compensation processing is performed on the received signal, the method further includes: and performing despreading processing on the signal subjected to timing recovery compensation.

Optionally, before modulating the digital signal to be transmitted, the method further includes: FEC coding processing is carried out on digital signals needing to be sent;

after the carrier recovery compensation processing is performed on the received signal, the method further includes: and performing FEC decoding processing on the signal subjected to the carrier recovery compensation processing.

A second aspect of an embodiment of the present invention provides a wireless data communication apparatus, including:

the system comprises a preamble symbol generating module, a preamble symbol generating module and a preamble symbol transmitting module, wherein the preamble symbol generating module is used for generating a sequence set of preamble symbols, and the sequence set of preamble symbols comprises a coarse synchronizing signal and a fine synchronizing signal;

the modulation module is used for modulating the digital signal to be transmitted to generate a modulation signal and inserting a preamble symbol sequence set in front of the modulation signal to form a transmission signal;

the synchronization module is used for receiving the transmitting signal, performing coarse synchronization and fine synchronization processing on the receiving signal, and acquiring the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal;

and the carrier adjusting module is used for carrying out timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal and carrying out carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase.

A third aspect of an embodiment of the present invention provides a wireless data communication apparatus, including:

the digital modulator is used for generating a sequence set of the preamble symbols, modulating a digital signal to be transmitted to generate a modulation signal, and inserting the sequence set of the preamble symbols in front of the modulation signal to form a transmission signal; wherein, the preamble symbol sequence set comprises a coarse synchronization signal and a fine synchronization signal;

the digital demodulator is used for receiving the transmitting signal, carrying out coarse synchronization and fine synchronization processing on the receiving signal, acquiring the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal, carrying out timing recovery compensation processing on the receiving signal according to the timing deviation and the carrier frequency deviation of the receiving signal, and carrying out carrier recovery on the receiving signal subjected to the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase.

Optionally, the digital modulator includes:

a preamble symbol generator for generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises a coarse synchronization signal and a fine synchronization signal;

the modulator is used for modulating the digital signal to be transmitted to generate a modulation signal;

a framer for inserting a set of sequences of preamble symbols prior to modulating a signal to form a transmitted signal;

and the digital transmitter is used for transmitting the transmitting signal.

Optionally, the digital demodulator includes:

the digital receiver is used for receiving the transmission signal transmitted by the digital transmitter;

the synchronizer is used for carrying out coarse synchronization and fine synchronization processing on the received signals received by the digital receiver to obtain the timing deviation, the carrier frequency deviation and the carrier phase of the received signals;

a timing restorer for performing timing restoration compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal;

and the carrier restorer is used for restoring the carrier of the received signal subjected to the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase.

Optionally, the synchronizer includes:

the coarse synchronization unit is used for multiplying the received linear frequency modulation pulse signal by a conjugate signal of a local reference signal, calculating a power spectrum of a multiplied signal, and performing coarse estimation on the carrier frequency deviation and the timing of a leading symbol starting boundary according to the maximum peak position of the power spectrum;

and the fine synchronization unit is used for performing coarse synchronization information compensation on the signal to be detected, performing correlation operation on the signal to be detected and the fine synchronization signal, determining the carrier frequency deviation and symbol timing of the received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to the phase information of the accumulated complex result corresponding to the effective energy output.

Optionally, the carrier recoverer includes:

the phase compensator is used for carrying out phase compensation on the received signal according to the output phase and outputting the obtained phase compensation signal;

the phase discriminator is used for carrying out phase discrimination processing on the phase deviation of the phase-compensated signal to obtain an estimated value of the phase difference;

the loop filter is used for filtering the estimated value of the phase difference to obtain a loop filtering output signal;

and the digital oscillator is used for performing integration processing on the loop filtering output signal according to the carrier frequency deviation and the carrier phase to obtain an output phase.

Optionally, the wireless data communication apparatus further includes a spreader and a despreader, the spreader is connected to the modulator, and the despreader is connected to the timing recoverer;

the frequency spreader is used for performing spread spectrum processing on the digital signal to be sent in a bit data redundancy mode and sending the digital signal to the modulator;

the modulator is used for modulating the transmitting signal after the spread spectrum processing;

and the despreader is used for despreading the received signals subjected to the timing recovery compensation processing.

Optionally, the wireless data communication device further includes an encoder and a decoder, the encoder is connected to the modulator, and the decoder is connected to the carrier restorer;

the encoder is used for carrying out FEC encoding processing on the digital signals to be sent and sending the digital signals to the modulator;

the modulator is used for modulating the transmitting signal after the coding processing;

and the decoder is used for carrying out FEC decoding processing on the received signals after the carrier recovery processing to obtain demodulated signals.

Compared with the prior art, the embodiment of the invention has the following beneficial effects: the embodiment of the invention completes the communication process of wireless data through two steps of signal sending and signal receiving, and generates a sequence set of preamble symbols firstly, wherein the sequence set of the preamble symbols comprises a coarse synchronization signal and a fine synchronization signal; modulating a digital signal to be transmitted to generate a modulated signal, and inserting a preamble symbol sequence set in front of the modulated signal to form a transmission signal; the method comprises the steps of carrying out coarse synchronization and fine synchronization processing on a received signal, obtaining timing deviation, carrier frequency deviation and carrier phase of the received signal, carrying out timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal, and carrying out carrier recovery on the received signal according to the carrier frequency deviation and the carrier phase. The preamble symbol is formed by adopting the coarse synchronization signal and the fine synchronization signal, and meanwhile, the coarse synchronization processing and the fine synchronization processing are respectively carried out in the process of receiving the signal so as to correctly detect the timing, the carrier frequency deviation and the carrier phase of the received signal, so that the signal can be quickly and effectively captured under the working condition of low SNR.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a flow chart of a wireless data communication method provided by an embodiment of the invention;

fig. 2 is a schematic structural diagram of a preamble symbol sequence provided in an embodiment of the present invention;

FIG. 3 is a waveform diagram of a coarse synchronization signal according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a structure of a transmitting signal according to an embodiment of the present invention;

FIG. 5 is a drawing of S provided by an embodiment of the present invention_upbasechirp(t) and S_{downbasechirp}(t) a schematic diagram of the structure of the signal;

fig. 6 is a flowchart illustrating a carrier recovery process according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a wireless data communication device according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a carrier recoverer according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of another wireless data communication device according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of another wireless data communication device according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a specific wireless data communication device according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

Example one

Referring to fig. 1, a flow chart diagram of the wireless data communication method of the present invention is shown, which is detailed as follows:

step S101, generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises a coarse synchronization signal and a fine synchronization signal.

Referring to fig. 2, the composition of a preamble symbol sequence is shown. As can be seen from the figure, the preamble symbol includes two parts, namely a coarse synchronization signal 201 and a fine synchronization signal 202, which are respectively used for the coarse synchronization process and the fine synchronization process of the subsequent received signal.

Optionally, the coarse synchronization signal 201 includes one or more continuous forward chirp signals and reverse chirp signals, and the fine synchronization signal includes a synchronization signal with an autocorrelation characteristic.

Referring to fig. 3, a coarse synchronization signal is shown, wherein a coarse synchronization signal comprises a plurality of forward chirps and a plurality of reverse chirps, and the number of the forward chirps and the number of the reverse chirps can be respectively configured independently and flexibly. The forward Chirp signal can be expressed as an Up Chirp signal, and the frequency of the Up Chirp signal is linearly increased along with time; the inverse Chirp signal may be represented as a Down Chirp signal whose frequency decreases linearly with time. Here, a portion composed of the Up Chirp signal is referred to as upchirp period, and a portion composed of the Down Chirp signal is referred to as Down Chirp period. The length of the last Up Chirp signal and the last Down Chirp signal can both be fractional, for example 1/4 length is generated for the first 1/4 truncation which is expressed as a full Up Chirp signal or Down Chirp signal length.

For the fine synchronization signal, a signal having an autocorrelation characteristic is selected. Autocorrelation is a measure of the degree of signal correlation, and can be regarded as the integral operation of the product of the signal multiplied by its own delayed signal, and the autocorrelation signal plays an important role in signal detection. Here, the m-sequence can be generated by constellation mapping by using a standard m-sequence, and the m-sequence is a linear pseudo-random sequence and has good autocorrelation characteristics. In addition, the length of the m-sequence can be flexibly configured according to the requirements of the system.

Step S102, modulating the digital signal to be transmitted to generate a modulated signal, and inserting the sequence set of the preamble symbols before the modulated signal to form a transmission signal.

In general, a digital signal to be transmitted is not suitable for long-distance transmission on a transmission channel, and therefore, the digital signal must be modulated to shift the signal from a low frequency to a high frequency before the signal can be transmitted in the channel. The digital modulation scheme here may be selected from various modulation schemes such as BPSK, QPSK, QAM, and (G) FSK. Referring to fig. 4, for a modulated signal, it needs to be combined with a preamble symbol 401 to generate a transmission signal, where a sequence set of preamble symbols 401 is inserted before a modulated signal 403, and according to the requirements of the system, a packet header 402 may also be inserted between the sequence set of preamble symbols 401 and the modulated signal 403, where the packet header is used to carry some control information of the physical layer.

And transmitting the combined transmitting signal after the transmitting signal is subjected to transmitting forming and up-sampling processing. For example, transmit shaping filtering typically employs a root-rising residual filter, whose impulse response function RC is the same as when BPSK digital modulation is employed₀(t) the following:

the roll-off factor alpha can be flexibly and fittingly arranged according to the application requirements of the system; t is_sIs a symbol duration period. The root raised cosine filter can achieve the effect of the raised cosine filter, and meanwhile, intersymbol interference is eliminated, and distortion of sampling points is avoided.

Since there is a certain difference between the data rate processed in the signal modulation process and the data rate required by D/a conversion and radio frequency transmission, the transmitted data needs to be up-sampled to make the data suitable for transmission in the D/a conversion module.

The signals after the emission forming processing and the up-sampling processing are subjected to D/A conversion to realize the conversion of data from digital signals to analog signals, and the analog signals after the D/A conversion are subjected to up-conversion, radio frequency I/Q quadrature modulation, power amplification and the like and then are emitted through an antenna.

Step S103, receiving the transmitting signal, and performing coarse synchronization and fine synchronization processing on the receiving signal to obtain the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal.

Similarly, corresponding to the signal transmission process, in the signal reception process, the antenna input signal needs to be processed by analog filtering, I/Q quadrature down-conversion, and the like, so as to output a low intermediate frequency or baseband analog signal. After obtaining the low intermediate frequency or baseband analog signal, the received signal needs to be sampled, so as to realize the conversion from the analog signal to the digital signal.

Corresponding to the transmit shaping process and the up-sampling process in the transmit signal, the receive signal needs to be down-sampled, receive shaped filtered, etc. at one end of the receive signal. The down-sampling process performs conversion of the input digital signal a/D sampling rate to a digital baseband sampling rate (e.g., 8 times the system symbol rate). When BPSK digital modulation is used, the receive shaping filter uses a root-rising residual rotation filter that is consistent with the transmit shaping.

After the receiving end completes the down-sampling processing and the receiving shaping filtering processing of the received signal, the receiving end needs to adopt the preamble symbol to perform the capture detection, the timing deviation, the carrier frequency deviation and the phase estimation on the received signal, thereby completing the correct demodulation of the received signal. The synchronization process is divided into two steps of coarse synchronization processing and fine synchronization processing.

Optionally, the performing coarse synchronization processing on the received signal includes: multiplying the received linear frequency modulation pulse signal with a conjugate signal of a local reference signal, calculating a power spectrum of the multiplied product signal, and roughly estimating the carrier frequency deviation and the timing of the starting boundary of the preamble symbol according to the maximum peak position of the power spectrum.

Illustratively, assuming that the carrier frequency deviation of the received signal is Δ f, the Chirp symbol timing deviation is Δ τ, and the slope of the Chirp signal frequency linearly changing with time is μ. And sequentially carrying out Up Chirp detection and Down Chirp detection on the received signal by taking a Chirp symbol as a unit.

First, the detection process for the Up Chirp is as follows: mixing the signal r (t) to be detected with the locally generated basic Down Chirp signal S_{downbasechirp}(t) multiplying, performing FFT operation on the multiplied output signal to obtain frequency domain power output pow _ up ═ abs (FFT (r (t) × S)_{downbasechirp})))²When the current signal is judged to be a valid Up Chirp signal according to the pow _ Up maximum peak value, the estimation of delta f + u delta tau can be obtained through the pow _ Up maximum peak value position index, wherein abs (·) is a function of solving amplitude.

Similar to the detection of the Up Chirp, the detection process of the Down Chirp signal is as follows: the signal r (t) to be detected and the locally generated basic Up Chirp signal S_upbasechirp(t) multiplying, performing FFT operation on the multiplied output signal, and obtaining a frequency domain power output pow _ down ═ abs (FFT (r (t) × S)_upbasechirp)))²When the current signal is judged to be an effective Down Chirp signal according to the pow _ Down maximum peak value, the estimation of the delta f-u delta tau can be obtained through the index of the pow _ Down maximum peak value position.

Referring to FIG. 5, a basic Up Chirp signal S is shown_upbasechirp(t) and a basic Down Chirp Signal S_do_wnba _sechirp(t) of (d). By combining the detection results of the Up Chirp and the Down Chirp, the estimation of Δ f and Δ τ can be obtained, thereby completing the rough estimation of the timing of the starting boundary of the pilot signals Up Chirp and Down Chirp symbols in the received signal and the carrier frequency deviation.

In addition, a plurality of continuous Up Chirp signals can be transmitted at the transmitting end, so that in the Up Chirp detection process, the frequency domain power output pow _ Up of a plurality of continuous symbols can be subjected to inter-symbol filtering to improve the detection performance, and the inter-symbol filtering can be performed by smoothing or IIR iterative filtering. Similarly, a plurality of continuous Down Chirp signals can be transmitted at the transmitting end, so that in the Down Chirp detection process, inter-symbol filtering can be performed on the frequency domain power output pow _ Down of a plurality of continuous symbols to improve the detection performance.

After the coarse synchronization processing of the signal is completed, the fine synchronization processing needs to be performed on the signal on the basis of the coarse synchronization processing.

Optionally, the performing fine synchronization processing on the received signal includes: and performing coarse synchronization information compensation on the signal to be detected, performing correlation operation on the signal to be detected and a fine synchronization signal, determining the carrier frequency deviation and symbol timing of the received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to the phase information of an accumulated complex result corresponding to the effective energy output.

Before fine synchronization processing, carrier frequency offset correction needs to be performed on a received signal according to carrier frequency offset obtained through coarse synchronization detection, and then fine synchronization detection needs to be performed on the corrected signal.

Illustratively, a Down Chirp signal is taken as an example to illustrate the fine synchronization processing process of the signal.

Suppose that the length of the downlink Chirpperiod part of the preamble symbol is T_downchirpOne standard Up Chirp or Down Chirp has a length T_chirpWhen the coarse synchronization detection is successful, the coarse timing of the corresponding first downlink Chirp start symbol boundary is t_sThe maximum possible residual timing deviation and carrier frequency deviation after the coarse synchronization is successful are STO respectively_ErrAnd CFO_Err。

The determined coarse timing of the start symbol boundary when the coarse synchronization detection is successful is t_sOn the basis of

As a starting reference point, in the following

An integer T_chirpPeriodic candidate timing point (t)₀，t₀+T_chirp，t₀+2*T_chirp，...，t₀+(N_c-1)*T_chirp) Two-dimensional searches of the time-frequency domain are performed in turn, where floor is expressed as a floor function.

Wherein, the time domain search and the frequency domain search can be simultaneously and concurrently carried out in the fine synchronization detection process, the reference standard of the time domain search is the estimation result of the timing deviation of the coarse synchronization, and the range is-STO_ErrTo STO_ErrThe timing search step accuracy depends on system performance requirements and can be four times the oversampling rate (time step 1/4 × t)_s) (ii) a The frequency domain search reference is the carrier frequency deviation estimation result of coarse synchronization, and the range is-CFO_ErrTo CFO_ErrThe frequency search precision step size is related to the fine synchronization signal length and the system performance requirements.

After the timing point and the search range of the search are determined, fine synchronization processing is started on the received signals, correlation operation needs to be carried out on the received signals and local known fine synchronization signals in the processing process, the correlation results are accumulated and the energy of the correlation results is output, once effective energy output is detected, fine synchronization detection is successful, the estimation results of timing and carrier frequency deviation of the fine synchronization signals are updated according to the time domain and frequency domain deviation of the current search, and meanwhile, the phase information of a corresponding correlation accumulation complex result of the effective energy output is utilized to obtain the estimation result of the current carrier phase.

And step S104, performing timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal, and performing carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase.

The timing recovery compensation process is used for tracking and compensating the drift of data sampling timing caused by clock deviation in the demodulation process of the received signal so as to ensure the correct demodulation of data. The data required when the timing recovery compensation processing is performed on the signal comprises the carrier frequency deviation of the received signal obtained by the synchronization processing, the receiving and transmitting sampling clock error can be estimated by the carrier frequency deviation of the received signal, and the timing pre-compensation processing is further performed on the data to be demodulated. Suppose that the carrier frequency offset is Δ f and the RF carrier frequency is f_cThen the transmit-receive sampling clock offset is estimated as: delta f/f_c. The detected timing offset is compensated for after the clock offset estimate is obtained. Alternatively, the timing recovery compensation process may be implemented by a delay locked loop.

Optionally, referring to fig. 6, performing carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency offset and the carrier phase includes steps S601 to S603.

Step S601, performing integration processing on the loop filter output signal according to the received carrier frequency offset and carrier phase to obtain an output phase.

Wherein the carrier frequency deviation and the carrier phase are carrier frequency deviation f determined after synchronous processing₀And a carrier phase theta 0, and performing frequency integration processing on the output fi (t) of the loop filter to obtain an output phaseAnd transmitting the signal to a phase compensation module for phase compensation.

Step S602, performing phase compensation on the received signal according to the output phase, outputting the obtained phase compensation signal, and performing phase discrimination processing on the phase deviation of the phase compensated signal to obtain an estimate of the phase difference.

And compensating the received signal according to the obtained phase compensation, wherein the compensated signal is the output of carrier recovery. Meanwhile, the compensated signal is also used as an input signal for phase discrimination processing, and the phase difference of the received signal is estimated through the phase discrimination processing.

Step S603, filter the estimated value of the phase difference to obtain a loop filter output signal.

And filtering the phase difference of the received signals obtained after phase discrimination to obtain frequency output. Wherein, the loop filter can select a first order or a multi-order structure.

Through the steps, the carrier frequency offset can be tracked, and the influence of the carrier frequency offset and the phase deviation on the received signal can be eliminated, so that the correct and stable demodulated signal can be obtained.

Through analysis in the background art, it can be known that the service rate can be effectively reduced through spread spectrum under the condition that the system symbol rate is certain, and meanwhile, higher anti-interference capability can be obtained through spread spectrum, and the frequency band utilization rate is improved. Therefore, the digital signal to be transmitted is spread before being modulated.

When the spreading factor is SF, the effective bit service rate after spreading is reduced to 1/SF before spreading. The spreading can be achieved by a data bit redundancy method, that is, input data is repeated SF times in units of each bit and is output in sequence. When the input bit stream is L, the output bit stream after spreading is L × SF. For the spreading, it can also be realized by a pseudo-random sequence or an orthogonal spreading code, which is not described herein again.

Similarly, corresponding to the data transmitting end, the received data needs to be despread at the data receiving end to recover the transmitted data.

Here, by performing the spread spectrum processing on the transmission signal first, the traffic rate can be reduced without reducing the physical symbol rate, and the performance limit of the reception sensitivity can be further reduced.

Optionally, before modulating the digital signal to be transmitted, the method further includes: and performing FEC encoding processing on the digital signals to be transmitted.

FEC coding is forward error correction coding that ensures reliable transmission of signals over long distances by adding redundant error correction codes to the transmission code sequence. Specifically, FEC encoding is performed on a signal to be transmitted, so that the error correction capability of data subjected to noise and environmental interference during transmission can be improved, and thus correct transmission of the data is ensured. FEC coding can be divided into convolutional codes and block codes, where convolutional codes not only have excellent error correction capability, but also have the advantages of smaller decoding delay and moderate implementation complexity compared with common linear block codes, so convolutional codes are used here.

Illustratively, the process of encoding data using convolutional codes is: when the convolutional code is (2, 1, K) (where K represents the constraint length), starting from the first input bit of the upper service data packet, serially coding bit by bit, where each input bit corresponds to 2 coded bits output; in order to ensure the reliability of decoding the last several data bits, K-1 tail bits 0 are usually filled in the tail of the input data bit, and after the decoding of the receiving end is finished, the corresponding tail bits need to be deleted.

Similarly, corresponding to the data transmitting end, the data receiving end needs to perform FEC decoding processing on the received data to recover the transmitted data.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

Compared with the prior art, the embodiment of the invention completes the communication process of wireless data through two steps of signal sending and signal receiving, and generates the sequence set of the preamble symbols firstly, wherein the sequence set of the preamble symbols comprises a coarse synchronizing signal and a fine synchronizing signal; modulating a digital signal to be transmitted to generate a modulated signal, and inserting a sequence set of preamble symbols in front of the modulated signal to form a transmission signal; the method comprises the steps of carrying out coarse synchronization and fine synchronization processing on a received signal, obtaining timing deviation, carrier frequency deviation and carrier phase of the received signal, carrying out timing recovery compensation processing on the received signal according to the timing deviation and the carrier frequency deviation of the received signal, and carrying out carrier recovery on the received signal after the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase. The preamble symbol is formed by adopting the coarse synchronization signal and the fine synchronization signal, and meanwhile, the received signal is subjected to coarse synchronization processing and fine synchronization processing so as to accurately detect the timing, carrier frequency deviation and carrier phase accurate estimation of the received signal, thereby being capable of quickly and effectively capturing the signal under the working condition of low SNR.

Example two

Corresponding to the wireless data communication method described in the first embodiment, the present invention provides a block diagram of a wireless data communication device.

And the leading symbol generating module is used for generating a sequence set of leading symbols, wherein the sequence set of leading symbols comprises a coarse synchronizing signal and a fine synchronizing signal.

And the modulation module is used for modulating the digital signal to be transmitted to generate a modulation signal and inserting the preamble symbol sequence set in front of the modulation signal to form a transmission signal.

And the synchronization module is used for receiving the transmitting signal, performing coarse synchronization and fine synchronization processing on the receiving signal, and acquiring the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal.

The wireless data communication device generates a coarse synchronization signal and a fine synchronization signal by arranging the preamble symbol generating module, performs coarse synchronization processing and fine synchronization processing on a received signal by the synchronization module at a receiving end, acquires timing deviation, carrier frequency deviation and carrier phase of the received signal by combining the coarse synchronization processing and the fine synchronization processing of the received signal, and finally performs carrier recovery on the received signal by the carrier adjusting module according to the timing deviation, the carrier frequency deviation and the carrier phase. The synchronous capture of the burst signal under the low SNR is realized by combining coarse synchronous detection and fine synchronous detection based on the Chirp signal.

EXAMPLE III

Fig. 7 shows a block diagram of a wireless data communication device according to an embodiment of the present invention, which corresponds to the wireless data communication method according to the first embodiment. For convenience of explanation, only the portions related to the present embodiment are shown.

Referring to fig. 7, the wireless data communication apparatus includes a digital modulator 70 and a digital demodulator 71.

A digital modulator 70 for generating a sequence set of preamble symbols, modulating a digital signal to be transmitted to generate a modulated signal, and inserting the sequence set of preamble symbols before the modulated signal to form a transmission signal; wherein, the preamble symbol sequence set comprises a coarse synchronization signal and a fine synchronization signal;

the digital demodulator 71 receives the transmission signal, performs coarse synchronization and fine synchronization on the reception signal, obtains a timing offset, a carrier frequency offset, and a carrier phase of the reception signal, performs timing recovery compensation processing on the reception signal according to the timing offset and the carrier frequency offset of the reception signal, and performs carrier recovery on the reception signal subjected to the timing recovery compensation processing according to the carrier frequency offset and the carrier phase.

Alternatively, the digital modulator 70 includes: a preamble symbol generator 7001 configured to generate a sequence set of preamble symbols, wherein the sequence set of preamble symbols includes a coarse synchronization signal and a fine synchronization signal; a modulator 7002 for modulating a digital signal to be transmitted to generate a modulated signal; a framer 7003 for inserting a set of sequences of preamble symbols before modulating the signal to form a transmission signal; and the digital transmitter 7004 is used for performing transmission processing on the transmission signal.

Optionally, the digital demodulator 71 includes: a digital receiver 7101 for receiving the transmission signal transmitted by the digital transmitter; a synchronizer 7102, configured to perform coarse synchronization and fine synchronization on the received signal received by the digital receiver 7101, and acquire a timing offset, a carrier frequency offset, and a carrier phase of the received signal; a timing recoverer 7103, configured to perform timing recovery compensation processing on the received signal according to the timing offset and the carrier frequency offset of the received signal; and a carrier restorer 7104, configured to perform carrier restoration on the received signal after the timing restoration compensation processing according to the carrier frequency offset and the carrier phase.

Optionally, synchronizer 7102 includes a coarse synchronization unit and a fine synchronization unit.

And the coarse synchronization unit is used for multiplying the received linear frequency modulation pulse signal by a conjugate signal of a local reference signal, calculating a power spectrum of a multiplied signal, and performing coarse estimation on the carrier frequency deviation and the timing of the starting boundary of the preamble symbol according to the maximum peak position of the power spectrum.

Optionally, referring to fig. 8, the carrier recoverer 7104 includes: phase compensator 801, phase detector 802, loop filter 803, and digital oscillator 804. A phase compensator 801 configured to perform phase compensation on the received signal according to an output phase, and output an obtained phase compensation signal; the phase discriminator 802 is configured to perform phase discrimination processing on the phase deviation of the phase-compensated signal to obtain an estimated value of the phase difference; a loop filter 803, configured to perform filtering processing on the estimated value of the phase difference to obtain a loop filter output signal; and the digital oscillator 804 is configured to perform integration processing on the loop filtering output signal according to the carrier frequency deviation and the carrier phase to obtain an output phase.

Optionally, referring to fig. 9, the wireless data communication apparatus further includes a spreader 7005 and a despreader 7105, the spreader 7005 is connected to the modulator 7002, and the despreader 7105 is connected to the timing recoverer 7103; the frequency spreader 7005 is configured to perform frequency spreading processing on a digital signal to be transmitted in a manner of bit data redundancy, and send the digital signal to the modulator 7002; the modulator 7002 is configured to modulate the transmission signal after the spread spectrum processing; the despreader 7105 is configured to perform despreading processing on the received signal after the timing recovery compensation processing.

Optionally, referring to fig. 10, the wireless data communication apparatus further includes an encoder 7006 and a decoder 7106, the encoder 7006 is connected to the modulator 7002, and the decoder 7106 is connected to the carrier restorer 7104; the encoder 7006 is configured to perform FEC encoding processing on the digital signal to be transmitted, and send the digital signal to the modulator 7002; the modulator 7002 is configured to modulate the transmission signal after the encoding processing; the decoder 7106 is configured to perform FEC decoding processing on the received signal after the carrier recovery processing, so as to obtain a demodulated signal.

Compared with the prior art, the embodiment of the invention realizes the communication of wireless data by arranging the digital modulator and the digital demodulator, and generates the sequence set of the preamble symbols by the preamble symbol generator, wherein the sequence set of the preamble symbols comprises a coarse synchronizing signal and a fine synchronizing signal; modulating a digital signal to be transmitted by a modulator to generate a modulated signal, and inserting a preamble symbol sequence set in front of the modulated signal by a framer to form a transmitting signal; transmitting the signals by a digital transmitter; the method comprises the steps of receiving transmitted data through a digital receiver, carrying out coarse synchronization and fine synchronization processing on a received signal through a synchronizer to obtain timing deviation, carrier frequency deviation and carrier phase of the received signal, carrying out timing recovery compensation processing on the received signal through a timing restorer according to the timing deviation and the carrier frequency deviation of the received signal, and carrying out carrier recovery on the received signal through the carrier restorer according to the carrier frequency deviation and the carrier phase to obtain accurate demodulation data. The received signals are respectively subjected to coarse synchronization processing and fine synchronization processing through the coarse synchronization unit and the fine synchronization unit so as to accurately detect the timing, carrier frequency deviation and carrier phase estimation of the received signals, and therefore the signals can be rapidly and effectively captured under the working condition of low SNR.

Example four

For ease of understanding, embodiments of the present invention provide a block diagram of another wireless data communication device. For convenience of explanation, only the portions related to the present embodiment are shown.

Generally, a digital communication system mainly includes a digital modulator, a D/a converter, a radio frequency transmitter, a radio frequency receiver, an a/D converter, a digital demodulator, and the like. The specific implementation of modulation and demodulation at the transmitter and receiver in the system will vary for different digital modulation techniques. Referring to fig. 10, the BPSK modulation technique is used as a reference, and the structure of the digital communication system is shown, and when other modulation techniques are adopted, the structure of the digital communication system is partially different from that of fig. 11.

The digital modulator 110 is configured to complete conversion from upper layer service data to a physical frame, input an upper layer effective service data bit, and output a physical frame digital signal. The digital modulator 110 mainly includes sub-modules, such as a preamble symbol generator 116, an FEC encoder 111, an interleaver 112, a spreader 113, a scrambler 114, a modulator 115, a framer 117, and a digital transmission front end 118, which are respectively described as follows:

the preamble symbol generator 116 is configured to generate a preamble symbol sequence, where the preamble symbol sequence includes two parts, namely a coarse synchronization signal and a fine synchronization signal, the coarse synchronization signal includes an Up Chirp signal and a Down Chirp signal, and the signals may be divided into two parts, namely, an upchirp period and a Down Chirp period. The fine synchronization signal is a synchronization signal having good correlation characteristics. The specific Up Chirp signal, the Down Chirp signal and the fine synchronization signal are described in detail in the first embodiment, and are not described herein again.

For a data signal to be transmitted, the data signal is first encoded by the FEC encoder 111, so as to enhance the interference resistance of data transmission in a channel. The data passed through the FEC encoder 111 is passed through an interleaver 112 to further improve interference rejection performance of the transmitted data. The original data sequence can be scrambled by the interleaver 112, so that the correlation between the data sequences before and after interleaving is weakened, the interleaving mode can be flexibly selected, and the signal can be interleaved by adopting a fixed row and column permutation mode.

The interleaved signal is processed by the spreader 113 to reduce the effective service rate, and the anti-interference capability of the signal can be enhanced by the spread spectrum processing. The signal is spread and then passed through a scrambler 114 to reduce bit repetition and the presence of long consecutive 0 or 1 bits in the data due to the spreading operation described above. Specifically, the m sequence has a good pseudo-random sequence characteristic and can be used as a scrambling code sequence. And performing binary logic exclusive OR operation on the bit data stream output by the spread spectrum module and the scrambling code sequence with the same length bit by bit, and then outputting the bit stream as scrambling. The scrambled signal is passed through a modulator 115 to perform digital modulation of the data binary bit stream.

The modulated signal output from the modulator 115 and the preamble symbol generated by the preamble symbol generator 116 are input to the framer 117, and the framer 117 combines the output modulated signal and the preamble symbol to obtain a physical frame signal. The obtained physical frame signal is processed by the digital transmission front end 118, the signal is processed by the transmission shaping process and the up-sampling process, the signal is output to the D/a converter 130, and the conversion from the digital signal to the analog signal is completed through the D/a converter. The D/a converted signal is output to the rf transmitter 140, and the signal transmitted by the rf transmitter 140 is further transmitted through an antenna.

At the signal receiving end, the demodulation of the signal is accomplished by the rf receiver 160, the a/D converter 150 and the digital demodulator 120.

The signal transmitted by the transmitting end is received at the signal receiving end through the antenna, the transmitted signal is processed by the radio frequency receiver 160 to obtain a low intermediate frequency or baseband signal, the obtained low intermediate frequency signal is processed by the a/D converter 150 to complete the signal sampling, and a sampled digital signal is obtained.

The digital demodulator 120 is mainly used for performing demodulation and receiving processing of the digital signal after a/D conversion, and includes sub-modules, such as a receiving digital front end 121, a synchronizer 122, a timing recoverer 123, a descrambler 124, a despreader 125, a carrier recoverer 126, a demapper 127, a deinterleaver 128, and an FEC decoder 129, which are respectively described as follows:

the sampled digital signal obtained by the a/D converter 150 is subjected to down-sampling and receive-shaping filtering processing by the receive digital front end 121. Transmitting the signal processed by the receiving digital front end 121 to the synchronizer 122 and the timing restorer 123, and performing capture detection and coarse estimation of the timing deviation, carrier frequency deviation and carrier phase of the physical frame by a coarse synchronization unit in the synchronizer 122; accurate estimation of the fine synchronization signal timing and carrier frequency offset is then accomplished via the fine synchronization unit in synchronizer 122 via the autocorrelation properties of the fine synchronization signal. While sending the data generated by the receiving digital front end 121 to the synchronizer 122, the data generated by the receiving digital front end 121 and the data output by the synchronizer are transmitted to the timing restorer 123, and the timing restorer 123 can obtain an estimate of a receiving and transmitting sampling clock error according to the receiving and transmitting carrier frequency deviation provided by the synchronizer 122, and further perform timing pre-compensation processing on the data to be demodulated.

The signal processed by the timing recoverer 123 sequentially passes through the descrambler 124 and the despreader 125. The transmit data portion signal is multiplied symbol-by-symbol by a descrambler 124 with the conjugate of a locally generated known descrambling signal, which is a digitally modulated signal of the transmit side scrambling sequence, to remove the effect of scrambling on the signal. The influence of the spreading on the received data in the transmitting end is removed by the despreader 125, and when the spreading factor is SF, the rate of the despread signal is 1/SF before spreading.

The despread data is sent to the carrier restorer 126, and the data output by the synchronizer is sent to the carrier restorer 126, and the data sent by the despreader 125 is used as an input signal, and on the basis of the carrier frequency offset and the phase information provided by the synchronizer 122, the carrier restorer 126 is used to remove the residual carrier frequency offset and the influence of the carrier frequency and the phase drift in the demodulation process, so as to ensure that a correct and stable demodulated signal is obtained. The carrier recoverer 126 may perform the effects of carrier frequency offset and phase offset on the signal through a digital phase locked loop.

The signal processed by the carrier recoverer 126 also needs to pass through a demapper 127, a deinterleaver 128, and an FEC decoder 129 in this order. It is easily understood that the deinterleaver 128 and the FEC decoder 129 are required to be provided at the receiving end corresponding to the interleaver 112 and the FEC encoder 111 at the transmitting end of the communication system. Meanwhile, the fine synchronization signal is generated by constellation mapping of the m-sequence signal at the transmitting end, and the influence of the constellation mapping on the received signal needs to be eliminated at the output end.

Specifically, the demapper 127 outputs a soft decision result in the FEC mode; in the non-FEC mode, the result to be judged is output. The signal passing through the demapper 127 is output to the deinterleaver 128, and the detailed operation of the deinterleaver 128 is related to the processing of the interleaver 112. The deinterleaved signal is processed by the FEC decoder 129 to perform corresponding decoding, and decoded bit data information is output. For example, when the FEC coding employs convolutional coding, the whole decoding process is performed using the Viterbi maximum likelihood algorithm.

According to the wireless data communication system, the preamble symbol sequence set is divided into the coarse synchronization signal and the fine synchronization signal, and then the received signal is subjected to coarse synchronization processing and fine synchronization processing at the signal receiving end, so that the timing deviation, the carrier frequency deviation and the carrier phase of the received signal are obtained, then the timing recovery compensation processing is carried out on the received signal through the timing restorer, and the carrier restorer carries out carrier recovery on the received signal according to the carrier frequency deviation and the carrier phase to obtain accurate demodulation data. In addition, the service rate is reduced by performing spread spectrum processing on the transmission signal, so that the receiver receiving sensitivity performance limit is effectively reduced. Meanwhile, the time overhead caused by the synchronization and demodulation processing delay of the whole receiving end is effectively reduced through the processes of synchronous capture of the synchronizer, carrier recovery demodulation of the carrier recoverer, convolution decoding and the like, the effective data throughput of the system is ensured, and the method can be applied to various networking environments.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims

1. A wireless data communication method, comprising signal transmission and signal reception, characterized in that,

generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises a coarse synchronization signal and a fine synchronization signal; the fine synchronization signal is a signal with autocorrelation characteristics and is generated by adopting a standard m sequence through constellation mapping;

receiving a transmitting signal, and performing coarse synchronization and fine synchronization processing on the receiving signal to acquire timing deviation, carrier frequency deviation and carrier phase of the receiving signal; wherein, the fine synchronization processing of the received signal comprises: performing coarse synchronization information compensation on a signal to be detected, performing correlation operation on the signal to be detected and a fine synchronization signal, determining the carrier frequency deviation and symbol timing of a received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to phase information of an accumulated complex result corresponding to effective energy output;

2. The wireless data communication method of claim 1, wherein the coarse synchronization signal comprises one to a plurality of consecutive forward chirp signals and reverse chirp signals;

the coarse synchronization processing of the received signal comprises: multiplying the received linear frequency modulation pulse signal with a conjugate signal of a local reference signal, calculating a power spectrum of the multiplied product signal, and roughly estimating the carrier frequency deviation and the timing of the starting boundary of the preamble symbol according to the maximum peak position of the power spectrum.

3. The wireless data communication method according to claim 1, wherein said carrier recovery of the received signal subjected to the timing recovery compensation process based on the carrier frequency offset and the carrier phase comprises,

4. The method of wireless data communication according to claim 1, further comprising, prior to said modulating the digital signal to be transmitted: performing spread spectrum processing on a digital signal to be transmitted in a bit data redundancy mode;

5. The wireless data communication method of claim 1,

before the modulating the digital signal to be transmitted, the method further comprises: FEC coding processing is carried out on digital signals needing to be sent;

6. A wireless data communication device, comprising:

the system comprises a preamble symbol generating module, a preamble symbol generating module and a preamble symbol transmitting module, wherein the preamble symbol generating module is used for generating a sequence set of preamble symbols, and the sequence set of preamble symbols comprises a coarse synchronizing signal and a fine synchronizing signal; the fine synchronization signal is a signal with autocorrelation characteristics and is generated by adopting a standard m sequence through constellation mapping;

the synchronization module is used for receiving the transmitting signal, performing coarse synchronization and fine synchronization processing on the receiving signal, and acquiring the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal; wherein, the fine synchronization processing of the received signal comprises: performing coarse synchronization information compensation on a signal to be detected, performing correlation operation on the signal to be detected and a fine synchronization signal, determining the carrier frequency deviation and symbol timing of a received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to phase information of an accumulated complex result corresponding to effective energy output;

7. A wireless data communication device, comprising:

the digital modulator is used for generating a sequence set of the preamble symbols, modulating a digital signal to be transmitted to generate a modulation signal, and inserting the sequence set of the preamble symbols in front of the modulation signal to form a transmission signal; wherein, the preamble symbol sequence set comprises a coarse synchronization signal and a fine synchronization signal; the fine synchronization signal is a signal with autocorrelation characteristics and is generated by adopting a standard m sequence through constellation mapping;

the digital demodulator is used for receiving the transmitting signal, performing coarse synchronization and fine synchronization processing on the receiving signal, acquiring the timing deviation, the carrier frequency deviation and the carrier phase of the receiving signal, performing timing recovery compensation processing on the receiving signal according to the timing deviation and the carrier frequency deviation of the receiving signal, and performing carrier recovery on the receiving signal subjected to the timing recovery compensation processing according to the carrier frequency deviation and the carrier phase; wherein, the fine synchronization processing of the received signal comprises: and performing coarse synchronization information compensation on the signal to be detected, performing correlation operation on the signal to be detected and a fine synchronization signal, determining the carrier frequency deviation and symbol timing of the received signal according to the searched time domain and frequency domain deviation when effective energy is detected, and determining the carrier phase of the received signal according to the phase information of an accumulated complex result corresponding to the effective energy output.

8. The wireless data communication apparatus of claim 7, wherein the digital modulator comprises:

a preamble symbol generator for generating a sequence set of preamble symbols, wherein the sequence set of preamble symbols comprises coarse synchronization symbols and fine synchronization symbols;

and the digital transmitter is used for transmitting the transmitting signal.

9. The wireless data communication device of claim 8, wherein the digital demodulator comprises:

10. The wireless data communication apparatus of claim 9, wherein the synchronizer comprises:

11. The wireless data communication apparatus of claim 9, wherein the carrier recoverer comprises:

12. The wireless data communication device of claim 9, further comprising a spreader and a despreader, the spreader coupled to the modulator and the despreader coupled to the timing recoverer;

13. The wireless data communication device according to claim 9, wherein the wireless data communication device further comprises an encoder and a decoder, the encoder coupled to the modulator and the decoder coupled to the carrier recoverer;