CN203872202U - Code division multiplexing quadrature frequency division multiple access communication system signal reception device - Google Patents

Abstract

A code division multiplexing orthogonal frequency division multiple access communication system signal receiving device, the first stage integration detection demodulation unit in the device includes N sub-channels, each sub-channel is connected by a signal multiplier and an integrator; the second The first-level correlation detection despreading unit includes N sub-channels, and each sub-channel is connected by a signal multiplier and a correlator, and the integrator is connected to the signal multiplier in the second-level correlation detection despreading unit in a one-to-one correspondence; The front-end module is sequentially connected to the ADC, the down-conversion module and the subcarrier signal replication module; the subcarrier signal replication module has parallel N output terminals, each output terminal is connected to a signal multiplier of the first-stage integral detection demodulation unit, and the correlator is connected to The data stream parallel-to-serial conversion module The data stream parallel-to-serial conversion module is sequentially connected to the data symbol demultiplexing module and the data symbol parameter estimation module.

Description

Signal receiving device for code division multiplexing orthogonal frequency division multiple access communication system

technical field

The utility model belongs to the technical field of mobile communication, and relates to a receiving device for realizing a code division multiplexing orthogonal frequency division multiple access communication system.

Background technique

Code division multiplexing/code division multiple access communication systems generally have very high channel bandwidth, but the anti-multipath interference performance is poor. In actual systems, the method of reducing the code rate or using narrow-band transmission is usually used, such as the one used in the global star system. Voice data transmission is a narrowband spread spectrum communication that can only support 10kbps order of magnitude.

Orthogonal frequency division multiplexing/orthogonal frequency division multiple access communication system has been widely used in ground mobile communication systems, and is known as the trend technology of the next generation of wireless communication (4G) in the future. This technology itself is to solve multipath interference It is designed to support higher data rates through multi-carrier transmission, 100Mbps or even higher. In addition, due to the use of orthogonal multi-carrier transmission technology, its frequency spectrum can overlap, which greatly improves the effective utilization of frequency resources. It is especially valuable under communication conditions with limited spectrum resources such as satellite communication.

At present, the relevant research fields at home and abroad generally combine the two systems of code division and orthogonal frequency division by choosing one of the two systems, that is, setting a selection switch and a processor module in the system transmitter, and selecting the transmission code division by switching the switch. Or orthogonal frequency division signals, the corresponding encoding, modulation, multiplexing and other operations are performed on the transmission signal through the processor module, and the same module should be set in the system receiving device; this kind of system design is very complicated and the cost is high. Moreover, only a single transmission mode can be selected at a switchover, and the design idea of combining the two systems of code division and orthogonal frequency division, that is, hybrid transmission and mutual compatibility, cannot be truly realized. This method of choosing one of the two is difficult to adapt to current and future communications. The development needs of system compatibility and scalability.

Contents of the invention

The problem solved by the technology of the present invention is: to overcome the deficiencies of the prior art, and provide a receiving device for implementing a code division multiplexing OFDMA communication system. The utility model can improve the anti-interference performance of the signal and expand the mutual compatibility performance of the communication system.

The technical solution of the present invention is: a code division multiplexing orthogonal frequency division multiple access communication system signal receiving device, including a radio frequency receiving front-end module, an ADC and a down-conversion module, a subcarrier signal replication module, and a first-stage integral detection demodulation unit , a second-stage correlation detection despreading unit, a data stream parallel-to-serial conversion module, a data symbol demultiplexing module, and a data symbol parameter estimation module;

The first-stage integration detection and demodulation unit includes N sub-channels, and each sub-channel is formed by connecting a signal multiplier and an integrator; the second-stage correlation detection and despreading unit includes N sub-channels, and each sub-channel is formed by a The signal multiplier is connected with a correlator, and the integrator is connected with the signal multiplier in the second-stage correlation detection despreading unit in a one-to-one correspondence; the radio frequency receiving front-end module is sequentially connected with the ADC, the down-conversion module and the subcarrier signal replication module; The sub-carrier signal replication module has N parallel output terminals, each output terminal is connected to a signal multiplier of the first-stage integral detection demodulation unit, and the correlator is connected to the data stream parallel-serial conversion module. The data stream parallel-serial conversion module is sequentially connected to the data symbols a demultiplexing module and a data symbol parameter estimation module;

The ADC and down-conversion module convert the RF signal received by the RF receiving front-end module into an intermediate frequency baseband subcarrier signal, and the subcarrier signal replication module replicates the intermediate frequency baseband subcarrier signal into N channels. The carrier signal is subjected to orthogonal demodulation and integrated processing to obtain a code division multiplexing subcarrier signal; the second-stage correlation detection and despreading unit performs correlation despreading on the code division multiplexing subcarrier signal of each channel to obtain N channels of original data symbols; The data stream parallel-to-serial conversion module converts the original data symbols of N paths from parallel transmission to serial transmission, and the original data symbols of multiple users are formed by the data symbol demultiplexing module; the data symbol parameter estimation module accurately performs multi-user original data symbols Parameter estimation and compensation equalization, and finally obtain the precise estimated value of the original data symbol.

Compared with the prior art, the present invention has beneficial effects as follows:

(1) The utility model adopts the mixed signal capable of simultaneously receiving two communication systems of code division and orthogonal frequency division, which effectively expands the mutual compatibility of the two communication systems, and is compatible with the advantages of the two systems themselves.

(2) The utility model adopts a two-stage integral correlation detection demodulation demodulation and despreading component unit (first demodulation and then despreading) in the functional module of the receiving device to realize the orthogonal demodulation of OFDMA signals, and to Correlation despreading is implemented on the demodulated code division multiplexing signal, so as to effectively obtain and recover the rough estimation value of the original data symbol.

(3) The utility model adopts a data symbol parameter estimation module based on the frequency domain in the functional module of the receiving device. Through the FFT transform domain, the parameter estimation of all original data symbols can be completed with only one division operation, and finally the original data symbols can be obtained. The precise estimated value of , the algorithm is simple and easy to operate, has good real-time performance, and is easy to implement.

Description of drawings

Fig. 1 is the functional module schematic diagram of the present utility model;

Fig. 2 is the principle diagram of the demodulation and despreading component unit of the present invention;

Fig. 3 is a structural diagram of the data symbol parameter estimation module of the utility model.

Detailed ways

Below in conjunction with accompanying drawing, structure of the present utility model is described. The signal receiving device of the code division multiplexing orthogonal frequency division multiple access communication system, as shown in Fig. A secondary correlation detection despreading unit, a data stream parallel-to-serial conversion module, a data symbol demultiplexing module, and a data symbol parameter estimation module;

As shown in Figure 2, the first-stage integration detection and demodulation unit includes N sub-channels, and each sub-channel is connected by a signal multiplier and an integrator; the second-stage correlation detection and despreading unit includes N sub-channels, and each sub-channel The channel is formed by connecting a signal multiplier and a correlator, and the integrator is connected to the signal multiplier in the second-stage correlation detection despreading unit in one-to-one correspondence; the RF receiving front-end module is connected to the ADC, the down-conversion module and the subcarrier signal in sequence Copying module; the subcarrier signal copying module has parallel N output ports, each output port is connected to a signal multiplier of the first-stage integral detection demodulation unit, and the correlator is connected to the data stream parallel-serial conversion module and the data stream parallel-serial conversion module sequentially Connect the data symbol demultiplexing module and the data symbol parameter estimation module; generally, N takes values from several values such as 64, 128, 256, 512, and 1024.

The RF receiving front-end module, ADC and down-conversion module are responsible for completing the frequency-locked/phase-locked reception, pre-selection filtering, analog-to-digital conversion, and Down conversion and other operations. After being processed by the RF receiving front-end module, ADC and down-conversion module, the IF baseband subcarrier signal is obtained.

The sub-carrier signal replication module is responsible for duplicating the obtained IF baseband sub-carrier signal (single channel) into multiple channels (N channels), each channel is regarded as a sub-channel, the first channel is defined as the 0th sub-channel, and the second channel is defined as the 0th sub-channel 1 sub-channel, the third channel is defined as the second sub-channel, and so on, until the N-th channel is defined as the N-1th sub-channel, each channel transmits the same OFDMA subcarrier signal, and each The subcarrier signal of one channel is sent to the demodulation and despreading component unit for processing.

The first stage integration detection and demodulation unit is responsible for the orthogonal demodulation of the OFDMA subcarrier signals of each channel, which is realized by the same orthogonal FFT operation (same number of points and same magnitude) as in the transmitting device. Afterwards, the OFDMA subcarrier signal of each channel becomes a code division multiplexing subcarrier signal.

The second-level correlation detection and despreading unit is responsible for correlating and despreading the code division multiplexing subcarrier signals of each channel through a group of pseudo-random spreading code groups (Gold sequences) that are the same as those in the transmitting device. After correlation, each channel The code division multiplexed subcarrier signal of is converted into original data symbols, and the original data symbols at this time have rough estimated values.

The data stream parallel-to-serial conversion module is responsible for converting the parallel raw data symbols with coarse estimated values from parallel transmission to serial transmission.

The data symbol demultiplexing module is responsible for operations such as unpacking, decomposing, and recombining serial original data symbols with rough estimated values to form multi-user original data symbols.

The data symbol parameter estimation module is responsible for accurate parameter estimation and compensation and equalization of the original data symbols with rough estimated values of multiple users, and finally obtains the fine estimated values of the original data symbols, and completes the reconstruction and recovery of multi-user data symbols.

As shown in Figure 2, the first-stage integral detection demodulation unit, the input end is a sub-channel composed of N channels transmitting the same OFDMA subcarrier signal, and each channel adopts a signal multiplier and integral detection A quadrature demodulator composed of a multiplier, wherein the signal multiplier is responsible for multiplying the received subcarrier signal of each channel with the locally generated coherent carrier, and the integral detector is responsible for integrating the multiplied output signal. And the multiple access signal integration of the sub-carrier frequency corresponding to the current sub-channel in the OFDMA sub-carrier signal is cleared to zero.

The integration detectors on each path have the same structure, and the integration period is the same; the signal multipliers on each path have the same structure, and the locally generated coherent carriers on each path are different and have the same coherence as the transmitting device. Carrier arrangement rules meet the requirements of multi-carrier orthogonality.

Let the OFDMA subcarrier signal of each channel (after being copied by the subcarrier signal copy module) be S(t), then the code division multiplexing subcarrier signal output by orthogonal demodulation is d _n , which can be expressed as [ 1] Calculate:

$\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}^{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}\\ <span\; class="notranslate">\; =</span><span\; class="notranslate">\; \&Integral;</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}\\ <span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ]</span>$

In formula [1], multi-subcarriers f ₀ , f ₁ , f ₂ , ..., f _N-1 are used to demodulate with OFDMA subcarrier signals on each channel respectively, and d _k is the Variables. The orthogonality of multi-carriers is used here. This orthogonality shows that the carriers can overlap each other without interfering with each other. The analytical formula is shown in formula [2]:

$<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; =</span>\begin{array}{c}\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; no</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ]</span>\end{array}$

In formula [2], when the local coherent carrier of a certain path is different from the subcarrier of the received OFDMA subcarrier signal, formula [2] will output 0, that is, the OFDMA subcarrier In the signal, the sub-carrier frequency corresponding to the current sub-channel is linearly independent of the multiple access signal integral, which improves the anti-interference performance of the communication system; when the local coherent carrier of a certain channel and the received OFDMA sub When the sub-carriers of the carrier signal are the same, formula [2] will output 1, and send out the corresponding demodulated CDM sub-carrier signal, which meets the requirements of multi-carrier orthogonal demodulation.

The second-stage correlation detection despreading unit, the input end is a sub-channel composed of N code-division multiplexing subcarrier signals after demodulation, and each path adopts an orthogonal despreading composed of a signal multiplier and a correlation detector Among them, the signal multiplier is responsible for multiplying the received subcarrier signal of each channel with the locally generated pseudo-random code, and the correlation detector is responsible for performing correlation operation on the multiplied output signal, and multiplexing the code The spreading code division multiplexing signals of other users that are not related to the spreading code corresponding to the current user in the subcarrier signal are cleared for non-correlation.

The correlation detectors on each path have the same structure, and the correlation integration period/symbol length is the same; the signal multipliers on each path have the same structure, and the locally generated pseudo-random codes on each path are also the same, and It has the same pseudo-random code arrangement rule as the transmitting device, and meets the requirements of the orthogonal despreading of the pseudo-random code.

For each CDM subcarrier signal d _n , formula [3] can be used to calculate the original data symbols with rough estimated values output by orthogonal despreading:

P _n ^e =∫d _n ×C(0)dr

=∫P _n ×C(r)×C(0)dr [3]

=P _n

In formula [3], C(0) represents the locally generated pseudo-random code, and C(r) represents the spreading code corresponding to the currently receiving user. Here, the sharp autocorrelation characteristic of the Gold pseudo-random code is used. This characteristic shows that only when the two codes are exactly the same can they reach the maximum correlation, otherwise they are extremely small (close to 0). The analytical formula is shown in formula [4]:

$<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ]</span>$

In formula [4], when the local pseudo-random code of a certain channel is irrelevant to the received user spreading code, formula [4] will output a minimum value, usually L is 511 or 1023, then the value → 0, that is, In the code division multiplexing subcarrier signal, the spreading code division multiplexing signals of other users that are not related to the spreading code corresponding to the current user are cleared for non-correlation, which further improves the anti-interference performance of the communication system; When the local pseudo-random code is coherent with the received user spreading code, the formula [4] will output 1, and send out the corresponding demodulated original data symbols with rough estimated values, satisfying the requirements of multi-user orthogonal despreading requirements.

As shown in FIG. 3 , in the CDMA OFDMA communication system signal receiving device described in the present invention, the data symbol parameter estimation module is responsible for parameter estimation of the original data symbols.

The rough estimate of the original data symbols and the rough estimate of the pilot symbols are also obtained. Since the pilot data is a known signal, the channel response factor caused by these pilot symbols passing through the transmission channel can be directly obtained, as shown in the formula As shown in [5] ( is the channel response value of the pilot symbol):

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; ]</span>$

Since the estimation algorithm is carried out in the frequency domain after the FFT transform domain, only one division operation is required to obtain the accurate estimation value of the original data symbol very conveniently through the channel response factor, as shown in formula [6]:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}^{\mathrm{<span\; class="notranslate">\; e</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; e</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; ]</span>$

At this point, the precise estimated value of the original data symbol is finally obtained, and the reconstruction and restoration of the data symbol is completed.

Parts not described in detail in the utility model belong to the common knowledge of those skilled in the art.

Claims (1)

1. A code division multiplexing orthogonal frequency division multiple access communication system signal receiving device, characterized in that it includes a radio frequency receiving front-end module, an ADC and a down-conversion module, a subcarrier signal replication module, a first-stage integral detection demodulation unit, and a first-stage integral detection demodulation unit. A secondary correlation detection despreading unit, a data stream parallel-to-serial conversion module, a data symbol demultiplexing module, and a data symbol parameter estimation module; The first-stage integration detection and demodulation unit includes N sub-channels, and each sub-channel is formed by connecting a signal multiplier and an integrator; the second-stage correlation detection and despreading unit includes N sub-channels, and each sub-channel is formed by a The signal multiplier is connected with a correlator, and the integrator is connected with the signal multiplier in the second-stage correlation detection despreading unit in a one-to-one correspondence; the radio frequency receiving front-end module is sequentially connected with the ADC, the down-conversion module and the subcarrier signal replication module; The sub-carrier signal replication module has N parallel output terminals, each output terminal is connected to a signal multiplier of the first-stage integral detection demodulation unit, and the correlator is connected to the data stream parallel-serial conversion module. The data stream parallel-serial conversion module is sequentially connected to the data symbols a demultiplexing module and a data symbol parameter estimation module; The ADC and down-conversion module convert the RF signal received by the RF receiving front-end module into an intermediate frequency baseband subcarrier signal, and the subcarrier signal replication module replicates the intermediate frequency baseband subcarrier signal into N channels. The carrier signal is subjected to orthogonal demodulation and integrated processing to obtain a code division multiplexing subcarrier signal; the second-stage correlation detection and despreading unit performs correlation despreading on the code division multiplexing subcarrier signal of each channel to obtain N channels of original data symbols; The data stream parallel-to-serial conversion module converts the original data symbols of N paths from parallel transmission to serial transmission, and the original data symbols of multiple users are formed by the data symbol demultiplexing module; the data symbol parameter estimation module accurately performs multi-user original data symbols Parameter estimation and compensation equalization, and finally obtain the precise estimated value of the original data symbol.