WO2021217896A1

WO2021217896A1 - Baseband transmitter, baseband receiver, modulation and demodulation system, and terminal

Info

Publication number: WO2021217896A1
Application number: PCT/CN2020/102268
Authority: WO
Inventors: 李晓明; 郑波浪; 李建龙; 刘伟; 熊艳伟
Original assignee: 北京升哲科技有限公司
Priority date: 2020-04-28
Filing date: 2020-07-16
Publication date: 2021-11-04
Also published as: CN111565161B; TW202141957A; TWI770560B; CN111565161A

Abstract

The present application discloses a baseband transmitter, a baseband receiver, a modulation and demodulation system, and a terminal. The baseband transmitter groups, by means of a Hadamard modulation module and according to the length of a preset spread spectrum signal, inputted digital signals to be transmitted; each signal group is mapped to a corresponding baseband modulation signal according to a preset Hadamard matrix, and each baseband modulation signal is transmitted to a scrambling module; a scrambling signal is generated by means of a scrambling signal generation module, and the scrambling signal is transmitted to the scrambling module; and the scrambling module performs, by using the scrambling signal, scrambling processing on the baseband modulation signal, so as to obtain a baseband scrambling signal.

Description

Baseband transmitter, baseband receiver, modem system and terminal

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 202010351136.2 on April 28, 2020, and the entire content of the above application is incorporated into this application by reference.

Technical field

This application relates to the field of communication technology, for example, to a baseband transmitter, a baseband receiver, a modem system, and a terminal.

Background technique

The baseband is a signal with a very narrow frequency range, that is to say, the amplitude spectrum is only non-zero near the origin (f=0), and other frequencies can be almost ignored. In telecommunications and signal processing, the baseband signal is transmitted without modulation, that is, the frequency range of the signal is not shifted, and the frequency is very low, including the frequency band from close to 0Hz to a higher cut-off frequency or maximum bandwidth. In the field of communication technology, how to transmit baseband signals has been extensively studied.

In the related art, the baseband transmitter modulates the baseband signal through multi-ary digital frequency modulation (MFSK), referred to as the multi-frequency system, and demodulates the modulated signal through the baseband receiver, so as to obtain the transmitted baseband signal.

This method leads to a large error in the signal obtained by demodulation of the baseband receiver and increases the hardware cost.

Summary of the invention

The present application provides a baseband transmitter, a baseband receiver, a modem system, and a terminal, so as to improve the accuracy of the signal demodulated by the baseband receiver without increasing the hardware cost.

A baseband transmitter is provided, including: a Hadamard modulation module, a scrambling signal generating module, and a scrambling module, wherein the Hadamard modulation module and the scrambling signal generating module are respectively connected to the scrambling module;

The Hadamard modulation module is configured to group the input digital signals to be transmitted according to the preset spread-spectrum signal length; map each signal group into a corresponding baseband modulation signal according to the preset Hadamard matrix, and map each signal to a corresponding baseband modulation signal. The baseband modulated signals are respectively transmitted to the scrambling module;

A scrambling signal generating module, configured to generate a scrambling signal, and transmit the scrambling signal to the scrambling module;

The scrambling module is configured to use the scrambling signal to perform scrambling processing on the baseband modulated signal to obtain a baseband scrambling signal.

A baseband receiver is also provided, including: a Hadamard demodulation module, a descrambling signal generation module, a descrambling module, and a decoder; the Hadamard demodulation module and the descrambling signal generation module are respectively connected to the descrambling module, and the Hadamard The demodulation module is connected to the decoder;

The descrambling signal generation module is configured to generate a descrambling signal and transmit the descrambling signal to the descrambling module;

The descrambling module is configured to use the descrambling signal to perform descrambling processing on the input baseband received signal to obtain a baseband descrambling signal, and to transmit the baseband descrambling signal to the Hadamard demodulation module;

A Hadamard demodulation module, configured to demodulate the baseband descrambling signal according to a preset Hadamard matrix, and transmit the demodulation result to the decoder;

The decoder is configured to perform binary decoding on the demapping result to obtain a baseband demodulated signal corresponding to the baseband received signal.

A modem system is also provided, including: the baseband transmitter according to any embodiment of the present application and the baseband receiver according to any embodiment of the present application.

A terminal is also provided, including the modem system described in any embodiment of the present application.

Description of the drawings

FIG. 1 is a schematic structural diagram of a baseband transmitter in Embodiment 1 of the present application;

2 is a schematic structural diagram of a baseband receiver in Embodiment 2 of the present application;

3 is a schematic structural diagram of a baseband receiver in Embodiment 3 of the present application;

FIG. 4 is a schematic structural diagram of a modem system in Embodiment 4 of the present application.

Detailed ways

Hereinafter, the embodiments of the present application will be further described in detail with reference to the accompanying drawings and embodiments. Example one

Figure 1 is a schematic structural diagram of a baseband transmitter in Embodiment 1 of the present application. This embodiment can be used to modulate and scramble a baseband signal to obtain a baseband scrambled signal to be transmitted. Referring to FIG. 1, the baseband transmitter 100 includes a Hadamard modulation module 110, a scrambling signal generating module 120 and a scrambling module 130.

Wherein, the Hadamard modulation module 110 and the scrambling signal generating module 120 are respectively connected to the scrambling module 130.

The Hadamard modulation module 110 is configured to group the input digital signals to be transmitted according to a preset spread-spectrum signal length; map each signal group into a corresponding baseband modulated signal according to the preset Hadamard matrix The baseband modulated signals are respectively transmitted to the scrambling module 130.

The length of the preset spreading signal is related to the spreading factor. For example, if the spreading factor is K, the length of the preset spreading signal is N=2^K, where K can be any positive integer. , It is not limited in the embodiments of this application.

Exemplarily, if the preset spreading factor is 10, which means that each preset spreading signal can transmit 10 bits of information, the digital signals to be transmitted can be grouped according to the preset spreading factor of 10, for example, , Starting from the first bit of information, sequentially divide the 10 bits of information into a group.

Optionally, the preset Hadamard matrix can be: a square matrix generated by Hadamard matrix construction methods such as Sylvester's construction or Paley construction; or, a square matrix. A matrix obtained by dual-polarization processing or a matrix obtained by extracting a subset of a square matrix.

Specifically, the dimension of the preset Hadamard matrix is N×L, where L can be equal to, greater than, or less than N, which is not limited in the embodiment of the present application. It can be understood that when L=N, the preset Hadamard matrix is a square matrix; when L<N or L>N, the preset Hadamard matrix is a matrix.

Among them, the preset Hadamard matrix can be generated iteratively by Sylvester's construction. At this time, L=N, and the number of bits transmitted by each signal b is equal to the spreading factor K; the preset Hadamard matrix can also be selected by selecting N×N Hadamard matrix. Generated from a subset of the matrix matrix. At this time, L can be greater than N, and the number of bits transmitted by each signal b is less than the spreading factor K. The advantage of this setting is that it can reduce the bit rate and increase the demodulation threshold; preset Hada The Ma matrix can also be generated by performing dual polarization processing on the N×N Hadamard matrix. In this case, L can be less than N, and the number of bits transmitted by each signal b is greater than the spreading factor K. The advantage of this setting is that Improve bit rate and spectrum utilization.

Optionally, the Hadamard modulation module 110 may include: a spread-spectrum signal grouping unit 111, a binary/decimal conversion unit 112, and a modulation unit 113 that are sequentially connected; wherein the spread-spectrum signal grouping unit 111 is configured to follow a preset spread spectrum The signal length groups the input digital signal to be transmitted, and transmits each signal packet to the binary/decimal conversion unit 112; the binary/decimal conversion unit 112 is configured to generate a decimal value that matches the input signal group, and convert the decimal The value is transmitted to the modulation unit 113; the modulation unit 113 is configured to select a data row matching the decimal value output by the binary/decimal conversion unit 112 in the Hadamard matrix, and map the data row to a baseband modulation signal matching the signal group .

Specifically, the spread-spectrum signal grouping unit 111 included in the Hadamard modulation module 110 groups the signals to be transmitted according to a preset spread-spectrum signal length, and transmits each grouped signal to the binary/decimal conversion unit 112 in turn.

The binary/decimal conversion unit 112 converts the received binary bit information into a decimal value, and transmits the converted decimal value to the modulation unit 113; exemplary, if the binary bit information is "0110", the converted decimal is "6", and transmit "6" to the modulation unit 113.

The modulation unit 113 selects a data row matching the decimal value from the determined Hadamard matrix, and maps the data row into a baseband modulation signal matching the signal group. Exemplarily, if the decimal value is "6" in the above example, the data in the sixth row of the Hadamard matrix can be mapped to a baseband modulated signal matching the signal group.

Specifically, the scrambling signal generating module 120 is configured to generate a scrambling signal, and transmit the scrambling signal to the scrambling module 130.

Among them, the scrambled signal in the embodiment of the present application may be a chirp signal. The scrambling signal in the embodiment of the present application may also be a pseudo-random sequence (m sequence or Gold code), which is not limited in the embodiment of the present application.

Optionally, the scrambling signal generating module 120 may be a chirp signal generating module. The scrambling module 130 is a multiplier; the scrambling module 130 is configured to multiply the baseband modulated signal and the chirp signal by corresponding elements to obtain the baseband scrambled signal; wherein the signal length of the chirp signal is the same as the signal length of the baseband modulated signal.

Specifically, the scrambling signal generating module 120 generates a chirp signal with the same length according to the length of the baseband modulation signal, and transmits the chirp signal to the scrambling module 130; the scrambling module 130 combines the baseband modulation signal with the scrambling signal generating module 120 The generated chirp signal is multiplied by corresponding elements to obtain a baseband scrambled signal. Among them, the baseband scrambled signal is the baseband transmit signal.

Optionally, the baseband transmitter involved in the embodiment of the present application further includes: a spreading factor selection module 140, which is connected to the Hadamard modulation module 110; and the spreading factor selection module 140 is configured to The spreading factor determined by at least one of the channel quality and the quality of service determines the length of the spread signal, and transmits the length of the spread signal to the Hadamard modulation module 110.

Specifically, the spreading factor selection module 140 determines the spreading factor K according to the information of at least one of the quality of the signal transmission channel and the quality of service (Quality of Service, QoS), and determines the length of the spreading signal according to the spreading factor K, and The length of the spread spectrum signal is transmitted to the Hadamard modulation module 110, and the Hadamard modulation module 110 further processes the digital signal to be transmitted according to the length of the spread spectrum signal.

The baseband transmitter in this embodiment uses the Hadamard modulation module 110 to group the input digital signals to be transmitted according to the preset spread-spectrum signal length; each signal group is mapped to the corresponding baseband according to the preset Hadamard matrix Modulate the signal, and transmit each baseband modulation signal to the scrambling module 130; generate the scrambling signal through the scrambling signal generation module 120, and transmit the scrambling signal to the scrambling module 130; use the scrambling through the scrambling module 130 The signal scrambles the baseband modulated signal to obtain the baseband scrambled signal, which realizes the modulation and scrambling of the digital signal to be transmitted, and provides a basis for the subsequent baseband receiver to quickly obtain the transmission signal. While ensuring the signal transmission speed, it can also Ensure the quality of signal transmission, and will not increase hardware costs.

Example two

2 is a schematic structural diagram of a baseband receiver in the second embodiment of the present application. This embodiment may be suitable for receiving a baseband scrambled signal transmitted by a baseband transmitter, and obtain the baseband demodulated signal from the baseband scrambled signal Condition. Referring to FIG. 2, the baseband receiver 200 includes a Hadamard demodulation module 210, a descrambling signal generation module 220, a descrambling module 230 and a decoder 240.

Among them, the Hadamard demodulation module 210 and the descrambling signal generation module 220 are respectively connected to the descrambling module 230, and the Hadamard demodulation module 210 is connected to the decoder 240.

Specifically, the descrambling signal generation module 220 is configured to generate a descrambling signal and transmit the descrambling signal to the descrambling module 230; the descrambling module 230 is configured to use the descrambling signal to descramble the input baseband received signal After processing, the baseband descrambling signal is obtained, and the baseband descrambling signal is transmitted to the Hadamard demodulation module 210; the Hadamard demodulation module 210 is configured to demodulate the baseband descrambling signal according to the preset Hadamard matrix, and The demodulation result is transmitted to the decoder 240; the decoder 240 is configured to perform binary decoding on the demodulation result to obtain a baseband demodulation signal corresponding to the baseband received signal.

Optionally, the descrambling signal generating module 220 may be a chirp signal generating module, that is, the descrambling signal generated by the descrambling signal generating module 220 may be a chirp signal. It should be noted that the descrambling signal generating module 220 involved in the embodiment of the present application corresponds to the scrambling signal generating module 120. When the scrambling signal generating module 120 is a chirp signal generating module, the descrambling signal generating module 220 is also a chirp signal generating module; when the scrambling signal generating module 120 is a pseudo-random sequence generating module, the descrambling signal generating module 220 is also a chirp signal generating module. Pseudo-random sequence generation module.

The descrambling module 230 uses the descrambling signal generated by the descrambling signal generating module 220 to descramble the input baseband received signal to obtain a descrambling signal, and transmit the descrambling signal to the Hadamard demodulation module 210.

Optionally, the descrambling module 230 is a multiplier, and the descrambling module 230 can multiply the baseband received signal and the chirp signal by corresponding elements to obtain the baseband descrambling signal; wherein, the signal length of the chirp signal is the same as the signal length of the baseband received signal same.

Specifically, the descrambling signal generating module 220 generates a chirp signal with the same length as the baseband received signal according to the length of the baseband received signal, and transmits the chirp signal to the descrambling module 230; the descrambling module 230 combines the baseband received signal with the descrambling signal The chirp signal generated by the generating module 220 is multiplied by corresponding elements to obtain a baseband descrambling signal.

The Hadamard demodulation module 210 demodulates the baseband descrambling signal according to the preset Hadamard matrix, and transmits the demodulation result to the decoder 240.

Optionally, the Hadamard demodulation module 210 may include: a connected fast Hadamard transform unit 211 and a decision unit 212; wherein the fast Hadamard transform unit 211 is configured to perform fast Hadamard transform on the baseband descrambling signal to determine the The decision unit 212 is configured to calculate the modulus of multiple demodulation soft values, determine the sequence number corresponding to the demodulation soft value with the largest modulus value as the estimated modulation value, and determine the demodulation result according to the estimated modulation value .

Specifically, after the Hadamard demodulation module 210 receives the baseband descrambling signal generated by the descrambling module 230, it performs a fast Hadamard transform on the baseband descrambling signal through the fast Hadamard transform unit 211, thereby determining multiple demodulation soft values ; Among them, the demodulation soft value is a complex number of the form a+bj, and a and b can be any real numbers. The decision unit 212 respectively calculates the modulus of each demodulation soft value, determines the sequence number corresponding to the demodulation soft value with the largest modulus as the estimated modulation value, and determines the demodulation result according to the estimated modulation value.

Exemplarily, if the demodulation soft value is 3+4j, the modulus of the demodulation soft value is

After finding the modulus of all the demodulation soft values, sort all the modulus values, and use the sequence number corresponding to the demodulation soft value with the largest modulus value as the estimated adjustment value; for example, the sequence number corresponding to the demodulation soft value with the largest modulus value is 10, you can use 10 as the estimated modulation value, and then determine the demodulation result according to the estimated modulation value.

The demodulation result is binary-decoded by the decoder 240 to obtain a baseband demodulated signal corresponding to the baseband received signal.

In this embodiment, the descrambling signal generation module 220 generates a descrambling signal, and transmits the descrambling signal to the descrambling module 230; the descrambling signal is used by the descrambling module 230 to perform descrambling processing on the input baseband received signal, Obtain the baseband descrambling signal, and transmit the baseband descrambling signal to the Hadamard demodulation module 210; through the Hadamard demodulation module 210, demodulate the baseband descrambling signal according to the preset Hadamard matrix, and The demodulation result is transmitted to the decoder 240; the demodulation result is binary-decoded by the decoder 240 to obtain the baseband demodulation signal corresponding to the baseband received signal, which realizes the realization of the received baseband demodulation signal. The received signal is demodulated, and the baseband demodulated signal can be obtained quickly without increasing the hardware cost.

Example three

FIG. 3 is a schematic structural diagram of a baseband receiver in the third embodiment of the present application. This embodiment refines the embodiment of the present application on the basis of the foregoing embodiment. The baseband receiver 200 may also include: a time-frequency synchronization module 250, a time-offset estimation module 260, and a frequency-offset estimation module 270; the time-frequency synchronization module 250 is respectively connected to the descrambling module 230, the time-offset estimation module 260, and the frequency-offset estimation module 270 , The time offset estimation module 260 is respectively connected to the descrambling signal generation module 220 and the decision unit 212, and the frequency offset estimation module 270 is connected to the decision unit 212.

Wherein, the time offset estimation module 260 is configured to determine the correlation value according to the demodulation result, the baseband descrambling signal and the compensation result determined by the decision unit 212, determine the time offset according to the correlation value, and transmit the time offset to the time-frequency synchronization module 250; The frequency offset estimation module 270 is configured to determine the frequency offset according to the phase of the demodulation result and the signal length determined by the decision unit 212, and transmit the frequency offset to the time-frequency synchronization module 250; the time-frequency synchronization module 250 is configured to estimate the frequency offset The frequency offset determined by the module 270 and the time offset determined by the time offset estimation module 260 compensate subsequent received signals, and the compensation results are transmitted to the Hadamard demodulation module 230 and the time offset estimation module 260 respectively.

Specifically, the time offset estimation module 260 determines the correlation value according to the demodulation result, the baseband descrambling signal, and the compensation result determined by the decision unit 212. For example, if the demodulation result determined by the decision unit 212 is

The baseband descrambling signal is

The compensation result is

Then the relevant value R is

and

The result of multiplying the corresponding elements of and then adding them together, where,

and

The dimensions are the same.

After the correlation value R is determined, the time offset estimation module 260 may estimate the time offset according to the correlation value R. In a specific example of the embodiment of the present application, the time offset can be determined by the formula (R _l+1 -R _l-1 )/(R _l+1 +R ₁ +R _l-1 ) or the formula (R _l+1- R _l-1 )/2(2R _l -R _l+1 -R _l-1 ) for estimation, where R _l+1 , R _l and R _l-1 are the correlation values corresponding to three consecutive baseband received signals . It should be noted that after the relevant values are determined in the embodiments of the present application, other methods may also be used to estimate the time offset, which is not limited in the embodiments of the present application.

Specifically, the frequency offset estimation module 270 determines the frequency offset according to the phase of the demodulation result determined by the decision unit 212 and the signal length, that is, the frequency offset estimation module 270 determines the phase of the demodulation soft value according to the maximum modulus value.

And the length of the signal determines the frequency offset. In a specific example of the embodiment of this application, the frequency offset can be determined by the formula

Make an estimate, where,

Is the phase of the demodulation soft value with the largest modulus value on the i-th signal, N is the number of sample points _{of the signal, and f s} is the sampling frequency of the signal. It should be noted that the frequency offset can also be estimated by other methods in the embodiment of the present application, which is not limited in the embodiment of the present application.

After the time offset and frequency offset are determined by the time offset estimation module 260 and the frequency offset estimation module 270, the time offset estimation module 260 and the frequency offset estimation module 270 respectively transmit the time offset and frequency offset to the time-frequency synchronization module 250; time-frequency synchronization The module 250 further compensates the subsequent received signal according to the received time offset and frequency offset, and transmits the compensation result to the Hadamard demodulation module 230 and the time offset estimation module 260 respectively.

Among them, the time-frequency synchronization module 250 can perform time offset compensation for the subsequent received signal by interpolation; the time-frequency synchronization module 250 can perform frequency offset compensation for the subsequent received signal by multiplying by exp(2pi*n*delta_f/fs), Among them, fs is the sampling rate, delta_f is the frequency offset estimate, that is, Δf involved in the above example, and pi is the pi. n is the sample number.

In this embodiment, the time offset and frequency offset of the baseband receiver are estimated through the time offset estimation module 260 and the frequency offset estimation module 270, and the time frequency synchronization module 250 is used to determine the frequency offset and time offset estimation module according to the frequency offset estimation module 270. The time offset determined by 260 compensates for the subsequent received signal, and transmits the compensation results to the Hadamard demodulation module 210 and the time offset estimation module 260, respectively, to realize the time domain and frequency domain compensation of the received signal, and to obtain accurate The baseband demodulation signal with higher rate provides the basis without increasing the hardware cost.

Example four

This embodiment provides a modulation and demodulation system, and this embodiment is applicable to a case where a baseband signal is modulated and demodulated by a baseband transmitter and a baseband receiver. The modem system may specifically include: a baseband transmitter as provided in the first embodiment and a baseband receiver as provided in at least one of the second and third embodiments.

In order to better understand the embodiments of the present application, FIG. 4 provides a schematic structural diagram of a modem system. The modem system 400 includes a baseband transmitter 410 and a baseband receiver 420.

Specifically, the spreading factor selection module 411 in the baseband transmitter 410 selects a specific spreading factor K according to information such as channel quality and QoS, and K further determines that the length of each Hadamard orthogonal spread spectrum signal is N=2^ K chips.

The Hadamard modulation module 412 in the baseband transmitter 410 converts the b bits of information transmitted on each Hadamard quadrature spread spectrum signal into the corresponding decimal modulation value M. This module generates an N*L Hadamard matrix. The M-th row of is used as the Hadamard quadrature spread spectrum modulation signal corresponding to the modulation value M

The scrambling module 413 in the baseband transmitter 410 converts the chirp signal with a length of N chips

with

Multiply by element

Obtain the baseband scrambled signal, that is, the scrambled baseband transmit signal.

The Hadamard demodulation module 421 in the baseband receiver 420 synchronizes the received signal with time and frequency

And chirp signal

Multiply by element

Get descrambling signal

right

Do the N-order fast Hadamard transform to get the demodulation soft value

The serial number corresponding to the soft value Dmax with the largest modulus value is the demodulation value

The demodulation value is further processed by the decoder at the bit level; the phase mark of Dmax is calculated

Get demodulated value

Corresponding Hadamard quadrature spread spectrum signal

The frequency offset estimation module 422 in the baseband receiver 420 uses the phase of the soft value with the largest modulus value on the multiple received signals.

The frequency offset is calculated with the length of the spread spectrum signal N, and multiple frequency offset estimations are filtered to obtain the frequency offset estimation result. The time offset estimation module 423 in the baseband receiver 420 converts the continuous spread spectrum signal

After chip delay and chirp signal

And demodulation value

Corresponding Hadamard quadrature spread spectrum modulation signal

Do related calculations

The time offset is estimated according to the correlation value, and multiple time offset estimators are filtered to obtain the time offset estimation result.

The time-frequency synchronization module 424 in the baseband receiver 420 uses the time offset estimation result fed back by the time offset estimation module 423 and the frequency offset estimation result fed back by the frequency offset estimation module 422 to make accurate compensation of the time offset and frequency offset.

It should be noted that the modulation and demodulation system involved in this embodiment can flexibly control the dimension N*L of the Hadamard matrix, which can achieve the purpose of flexibly controlling the bit rate of transmission; where L may be equal to N, at this time Hadamard The matrix is iteratively generated by the Sylvester generation method, and the number of bits transmitted by each spread signal is equal to the spreading factor b equals K; the Hadamard matrix can also be determined by subsetting the N*N Hadamard matrix, and L can be greater than N and b are less than K, which can reduce the bit rate and increase the demodulation threshold; the Hadamard matrix can also be determined by dual-polarization processing on the N*N Hadamard matrix. At this time, L can be less than N and b greater than K , Which can improve the bit rate and spectrum utilization.

The scheme of this embodiment modulates and scrambles the baseband signal through the baseband transmitter; descrambling and Hadamard demodulation is performed on the input signal through the baseband receiver, and the signal is compensated for time offset and frequency offset at the same time. While the baseband demodulates the signal with precision, it can reduce the hardware implementation cost and reduce the power consumption.

Example five

This embodiment provides a terminal, and this embodiment is applicable to a case where a baseband signal is modulated and demodulated by a baseband transmitter and a baseband receiver. The terminal may specifically include: the modulation and demodulation system provided in the fourth embodiment.

Claims

A baseband transmitter, comprising: a Hadamard modulation module, a scrambling signal generating module, and a scrambling module, wherein the Hadamard modulation module and the scrambling signal generating module are respectively connected to the scrambling module;

The Hadamard modulation module is configured to group the input digital signals to be transmitted according to the preset spread-spectrum signal length; map each signal group into a corresponding baseband modulation signal according to the preset Hadamard matrix, and map each signal to a corresponding baseband modulation signal. The baseband modulated signals are respectively transmitted to the scrambling module;

A scrambling signal generating module, configured to generate a scrambling signal, and transmit the scrambling signal to the scrambling module;

The scrambling module is configured to use the scrambling signal to perform scrambling processing on the baseband modulated signal to obtain a baseband scrambling signal.
The baseband transmitter according to claim 1, wherein the scrambling signal generating module is a chirp signal generating module, and the scrambling module is a multiplier.
The baseband transmitter according to claim 2, wherein the scrambling module is configured to multiply the baseband modulated signal and the chirp signal by corresponding elements to obtain a baseband scrambled signal;

Wherein, the signal length of the chirp signal is the same as the signal length of the baseband modulation signal.
The baseband transmitter according to claim 1, further comprising: a spreading factor selection module, and the spreading factor selection module is connected to the Hadamard modulation module;

The spreading factor selection module is configured to determine the length of the spreading signal according to the spreading factor determined by at least one of the channel quality and the quality of service, and transmit the length of the spreading signal to the Hadamard modulation module.
The baseband transmitter according to any one of claims 1-4, wherein the Hadamard modulation module comprises: a spread spectrum signal grouping unit, a binary/decimal conversion unit and a modulation unit that are sequentially connected;

A spread-spectrum signal grouping unit, configured to group the input digital signal to be transmitted according to the preset spread-spectrum signal length, and transmit each signal group to the binary/decimal conversion unit;

The binary/decimal conversion unit is configured to generate a decimal value matching the input signal group, and transmit the decimal value to the modulation unit;

The modulation unit is configured to select, in the Hadamard matrix, a data row matching the decimal value output by the binary/decimal conversion unit, and map the data row to a baseband modulation signal matching the signal group.
The baseband transmitter according to claim 1, wherein the preset Hadamard matrix is:

Square matrix generated by Sylvester construction method or Paley construction method;

or,

A matrix obtained by performing dual polarization processing on the square matrix or a matrix obtained by extracting a subset of the square matrix.
A baseband receiver, comprising: a Hadamard demodulation module, a descrambling signal generation module, a descrambling module, and a decoder; wherein the Hadamard demodulation module and the descrambling signal generation module are separately connected to the descrambling signal generation module. The scrambling module is connected, and the Hadamard demodulation module is connected to the decoder;

A descrambling signal generation module, configured to generate a descrambling signal, and transmit the descrambling signal to the descrambling module;

The descrambling module is configured to use the descrambling signal to perform descrambling processing on the input baseband received signal to obtain a baseband descrambling signal, and to transmit the baseband descrambling signal to the Hadamard demodulation module;

A Hadamard demodulation module, configured to demodulate the baseband descrambling signal according to a preset Hadamard matrix, and transmit the demodulation result to the decoder;

The decoder is configured to perform binary decoding on the demodulation result to obtain a baseband demodulated signal corresponding to the baseband received signal.
The baseband receiver according to claim 7, wherein the descrambling signal generating module is a chirp signal generating module, and the descrambling module is a multiplier.
The baseband receiver according to claim 8, wherein the descrambling module is configured to multiply the baseband received signal and the chirp signal by corresponding elements to obtain a baseband descrambling signal;

Wherein, the signal length of the chirp signal is the same as the signal length of the baseband received signal.
The baseband receiver according to claim 7, 8 or 9, wherein the Hadamard demodulation module comprises: a fast Hadamard transform unit and a decision unit connected;

The fast Hadamard transform unit is configured to perform fast Hadamard transform on the baseband descrambling signal to determine multiple demodulation soft values;

The decision unit is configured to calculate multiple modulus values of the demodulation soft values, determine the sequence number corresponding to the demodulation soft value with the largest modulus value as the estimated modulation value, and determine the demodulation result according to the estimated modulation value.
The baseband receiver according to claim 10, further comprising: a time-frequency synchronization module, a time-offset estimation module, and a frequency-offset estimation module; wherein the time-frequency synchronization module is connected to the descrambling module and the time-offset estimation module, respectively Module and the frequency offset estimation module are connected, the time offset estimation module is respectively connected with the descrambling signal generation module and the decision unit, and the frequency offset estimation module is connected with the decision unit;

The time offset estimation module is configured to determine a correlation value according to the demodulation result, the baseband descrambling signal and the compensation result determined by the decision unit, determine the time offset according to the correlation value, and compare the time offset Transmitted to the time-frequency synchronization module;

A frequency offset estimation module, configured to determine a frequency offset according to the phase of the demodulation result and the signal length determined by the decision unit, and transmit the frequency offset to the time-frequency synchronization module;

The time-frequency synchronization module is configured to compensate subsequent received signals according to the frequency offset determined by the frequency offset estimation module and the time offset determined by the time offset estimation module, and transmit the compensation results to The Hadamard demodulation module and the time offset estimation module.
A modem system, comprising: the baseband transmitter according to any one of claims 1-6, and the baseband receiver according to any one of claims 7-11.
A terminal comprising the modem system according to claim 12.