A communication method and apparatus supporting GMSK and QPSK

Abstract

The present application relates to a communication method and apparatus supporting GMSK and QPSK, and pertains to the technical field of communications. The communication method includes: selecting GMSK or QPSK as the modulation method at the transmitting end according to signaling configuration information to modulate a signal to be modulated, so as to obtain a modulated signal; in response to selecting GMSK as the modulation method at the transmitting end, obtaining a linear expression of the signal to be modulated, where the signal to be modulated is obtained by subjecting a source information sequence to pre-processing before modulation; performing synchronization processing and filtering processing on the modulated signal to obtain a synchronization signal at the receiving end; performing equalization pre-processing on the synchronization signal at the receiving end by means of an equalization pre-processing method corresponding to the modulation method at the transmitting end to obtain an equalization pre-processed signal; performing frequency-domain equalization processing on the equalization pre-processed signal by means of a shared frequency-domain equalization method to obtain a soft output signal; and performing decoding processing on the soft output signal to obtain the source information sequence. The present application can utilize the advantages of GMSK and QPSK to save communication costs.

Description

Technical Field

[0001] The present application relates to the field of communications, and in particular, to a communication method and apparatus supporting GMSK and QPSK. Background Art

[0002] Existing GMSK (Gaussian Minimum Shift Keying modulation) and QPSK (Quadrature Phase Shift Keying modulation) are two different modulation methods. They modulate and demodulate the source information sequence through their respective independent systems and are not compatible with each other. In the data detection during the demodulation process of existing GMSK, MLSE can be used, and MLSE is implemented through a Viterbi detector. For example, at the receiving end, the transmitted MSK symbol sequence is found, then mapped into binary information, and the previously transmitted MSK symbol sequence is estimated through the Viterbi detector. For the specific steps, reference can be made to the content of the background art in the patent with the publication number CN110753011A. From the content of the above background art, it can be seen that the existing GMSK system is sufficient for a 250K GSM system, but cannot meet the requirements of a high-rate (10Mbit / s) GMSK system. Therefore, the existing demodulation method of the GMSK system is difficult to be used in a high-rate GMSK communication system. Moreover, the spectral efficiency of GMSK is relatively low (one symbol represents 1 bit) and cannot meet the requirements of high-rate signals, but GMSK has a low peak-to-average ratio and has the advantage of a longer transmission distance. While QPSK has a high spectral efficiency (one symbol represents 2 bits) and can perform high-capacity communication, it cannot meet the requirements of transmitting signals over a long distance.

[0003] Therefore, how to utilize the respective advantages of GMSK and QPSK to meet different requirements for signal transmission (high-speed transmission or long-distance transmission), and at the same time enable these two modulation methods to share some network devices to save communication costs is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] The objective of the present application is to provide a communication method supporting GMSK and QPSK, which jointly utilizes the advantages of GMSK with a long transmission distance and QPSK with a high spectral efficiency. For signals that need to be transmitted at high speed, the QPSK modulation method is selected, and for signals that need to be transmitted over a long distance, the GMSK modulation method is selected. At the same time, GMSK and QPSK can share some network devices to save communication costs.

[0005] In a first aspect, the present application provides a communication method supporting GMSK and QPSK, including the following steps: Select GMSK or QPSK as the modulation method at the transmitting end according to the signaling configuration information generated by the network device to modulate the signal to be modulated, so as to obtain the modulated signal, and in response to selecting GMSK as the modulation method at the transmitting end, obtain the linear expression of the signal to be modulated before modulating the signal to be modulated, where the signal to be modulated is obtained after pre-modulation processing of the source information sequence; Perform synchronization processing and filtering processing on the modulated signal to obtain the synchronization signal at the receiving end; Perform equalization preprocessing on the synchronization signal at the receiving end through an equalization preprocessing method corresponding to the modulation method at the transmitting end to obtain the equalization preprocessed signal; Perform frequency domain equalization processing on the equalization preprocessed signal through a common frequency domain equalization method to obtain the soft output signal; Perform decoding processing on the soft output signal to obtain the source information sequence.

[0006] By adopting the above technical solution, the QPSK modulation method can be selected for signals that need to be transmitted at high speed, and the GMSK modulation method can be selected for signals that need to be transmitted over a long distance, making full use of the advantages of GMSK with a long transmission distance and QPSK with high spectral efficiency, and at the same time enabling GMSK and QPSK to share the frequency domain equalization device.

[0007] Optionally, the decoding process for the soft output signal includes: Demultiplexing the soft output signal through a common demultiplexing method to obtain the demultiplexed signal.

[0008] By adopting the above technical solution, GMSK and QPSK can share the same demultiplexing device, saving costs.

[0009] Optionally, the decoding process for the soft output signal further includes: Deinterleaving the demultiplexed signal through a common deinterleaving method to obtain the deinterleaved signal.

[0010] By adopting the above technical solution, GMSK and QPSK can share the same deinterleaving device, further saving costs.

[0011] Optionally, the decoding process for the soft output signal further includes: Decoding the deinterleaved signal through a common decoding method to obtain the source information sequence.

[0012] By adopting the above technical solution, GMSK and QPSK can share the same decoding device, further saving costs.

[0013] Optionally, the synchronization processing and filtering processing of the modulated signal include: inserting a common synchronization header of the transmitting end into the modulated signal to generate a transmitting-end synchronization signal; filtering the transmitting-end synchronization signal through a receiving-end filtering method corresponding to the transmitting-end modulation method to obtain a filtered signal; and synchronizing the filtered signal through a receiving-end common synchronization processing method corresponding to the transmitting-end common synchronization header to obtain a receiving-end synchronization signal.

[0014] By adopting the above technical solution, GMSK and QPSK can share the same synchronization header at the transmitting end and the same synchronization processing method at the receiving end, simplifying the communication process.

[0015] Optionally, the common synchronization header of the transmitting end uses the GMSK modulation method or the QPSK modulation method.

[0016] By adopting the above technical solution, any modulation method can be selected according to the actual situation during the operation process to measure the frequency offset and timing synchronization.

[0017] Optionally, the linear expression of the signal to be modulated is:

[0018]

[0019] where I k is the data after differential encoding of the source information sequence, j k is the k-th power of the imaginary number, and C0(t - kT) is a time-limited amplitude modulation pulse.

[0020] By adopting the above technical solution, GMSK can be approximated as a linear modulation, so the equalization technology applicable to QPSK can be easily transplanted into the GMSK system, providing a basis for sharing the frequency domain equalization device between QPSK and GMSK.

[0021] Optionally, the communication method further includes: adding a preamble signal or a pilot training signal to the modulated signal, and the preamble signal or the pilot training signal corresponding to different transmitting-end modulation methods is the same.

[0022] By adopting the above technical solution, QPSK and GMSK can share the same preamble signal or pilot training signal, saving communication resources.

[0023] Optionally, the modulation method of the preamble signal or the pilot training signal is the same as the transmitting-end modulation method.

[0024] In a second aspect, the present application provides a communication device supporting GMSK and QPSK, including: a transmitting-end modulation module configured to select GMSK or QPSK as the transmitting-end modulation method according to the signaling configuration information generated by a network device to modulate a signal to be modulated, so as to obtain a modulated signal, and in response to selecting GMSK as the transmitting-end modulation method, obtain a linear expression of the signal to be modulated before modulating the signal to be modulated, where the signal to be modulated is obtained by performing pre-modulation processing on a source information sequence; a synchronization filtering module configured to perform synchronization processing and filtering processing on the modulated signal to obtain a receiving-end synchronization signal; an equalization preprocessing module configured to perform equalization preprocessing on the receiving-end synchronization signal through an equalization preprocessing method corresponding to the transmitting-end modulation method to obtain an equalization preprocessed signal; a frequency-domain equalization processing module configured to perform frequency-domain equalization processing on the equalization preprocessed signal through a common frequency-domain equalization method to obtain a soft output signal; and a decoding module configured to perform decoding processing on the soft output signal to obtain the source information sequence; the transmitting-end modulation module, the synchronization filtering module, the equalization preprocessing module, the frequency-domain equalization processing module, and the decoding module are connected in sequence.

[0025] By adopting the above technical solution, for signals that need to be transmitted at high speed, the QPSK modulation method can be selected, and for signals that need to be transmitted over a long distance, the GMSK modulation method can be selected, making full use of the advantages of GMSK having a long transmission distance and QPSK having high spectral efficiency. At the same time, GMSK and QPSK can share the frequency-domain equalization device, and the same architecture can implement two communication methods. This saves costs.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] 1. Combining and making use of the advantages of GMSK having a long transmission distance and QPSK having high spectral efficiency, selecting the QPSK modulation method for signals that need to be transmitted at high speed and the GMSK modulation method for signals that need to be transmitted over a long distance;

[0028] 2. Enabling GMSK and QPSK to share network resources and saving communication costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic flowchart of a communication method supporting GMSK and QPSK according to an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of a data frame structure in a communication method supporting GMSK and QPSK according to an embodiment of the present application;

[0031] Figure 3It is a schematic flowchart of synchronizing and filtering the aforementioned modulated signal according to one embodiment of the present application;

[0032] Figure 4 It is an additive white Gaussian noise simulation diagram of two modulation methods in a communication method supporting GMSK and QPSK according to one embodiment of the present application;

[0033] Figure 5 It is a simulation of a suburban channel of two modulation methods in a communication method supporting GMSK and QPSK according to one embodiment of the present application;

[0034] Figure 6 It is a structural framework diagram of a communication device supporting GMSK and QPSK according to one embodiment of the present application. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the following will further elaborate on the present application in conjunction with the attached Figure 1 - attached Figure 6 - and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] GMSK uses a digital modulation method called 0.3GMSK. 0.3 represents the ratio of the Gaussian filter bandwidth to the bit rate. GMSK is a special digital FM modulation method, that is, by adding or subtracting detf MHz to the RF carrier frequency to represent 1 and 0. The modulation technique of representing 1 and 0 by two frequencies is called FSK (Frequency Shift Keying). In GMSK, the data rate is selected as fs Mbit / sec, which is exactly 4 times the RF frequency offset detf (fs = 4 * detf). In this way, the modulation spectrum can be minimized and the channel efficiency can be improved. The FSK modulation in which the bit rate is exactly 4 times the frequency offset is called MSK (Minimum Shift Keying). GMSK uses a Gaussian pre-modulation filter to further reduce the modulation spectrum, which can reduce the frequency conversion speed and avoid the energy radiation to adjacent channels caused by rapid frequency conversion. In addition, since GMSK has a constant envelope, its peak-to-average ratio does not increase significantly after passing through a digital filter. Therefore, the peak-to-average ratio of GMSK is lower than that of QPSK. Thus, when the user rate of GMSK is reduced by half and long-distance communication needs to be ensured at the same time, due to the low peak-to-average ratio of GMSK, long-distance communication can be achieved. The basic transmission process of GMSK and the transmission modulation technique of QPSK are prior arts and will not be elaborated herein.

[0037] Refer to Figure 1 and Figure 2, this application provides a communication method supporting GMSK and QPSK, including steps S101 - S105. At step S101, according to the signaling configuration information (including modulation mode) generated by the network device, GMSK or QPSK is selected as the modulation mode at the transmitting end to modulate the signal to be modulated, so as to obtain the modulated signal. Here, the signal to be modulated is obtained after pre - modulation processing of the source information sequence. In one application scenario, the source information sequence can be a source binary information sequence generated by a source pseudo - random sequence generator. In one embodiment, the data frame structure in the aforementioned communication method is as Figure 2 shown, where the synchronization hop only transmits synchronization information data, the data hop only transmits data information, and the sum of all data in one hop is 1326 symbols. The pre - modulation processing may include a series of preparatory work before modulation such as parameter setting, channel coding, interleaving, generating burst data, etc.

[0038] To enable QPSK and GMSK to share the frequency - domain equalization device, when GMSK is selected as the modulation mode at the transmitting end, before modulating the aforementioned signal to be modulated, it is necessary to obtain the linear expression of the signal to be modulated, so as to approximate GMSK as a linear modulation. For example, the amplitude - modulated pulse (AMP) decomposition of binary continuous - phase modulation (Binary CPM) provides a very accurate linear approximation for CPM (continuous - phase modulation), and then the equalization technology applicable to QPSK can be conveniently transplanted into the GMSK system. In one embodiment, the linear expression of the signal to be modulated is:

[0039]

[0040] where I k is the data after differential encoding of the source information sequence, j k is the k - th power of the imaginary number, and C0(t - kT) is a time - limited amplitude - modulated pulse. This linear expression provides a basis for QPSK and GMSK to share the frequency - domain equalization device, and its derivation process is as follows: Since the aforementioned source information sequence needs to be differentially encoded before modulating the signal to be modulated, then there is: where a = [...a0, a1, a2,...] is the transmitted source information sequence, where a i ∈{-1, 1}.

[0041] Also, because So j^A can be simplified to: j A = l k j k

[0042] If the initial phase is ignored, the GMSK baseband signal can be expressed as:

[0043]

[0044] Meanwhile, the amplitudes of C1(t), C2(t), C3(t), etc. are very small compared to C0(t) and can be ignored. Therefore, the expression of the GMSK baseband signal can be further simplified as:

[0045]

[0046] Therefore, the equalization technique applicable to linear modulation can be applied to the demodulation scheme of GMSK signals.

[0047] In practical applications, this communication method further includes: adding a preamble signal or a pilot training signal to the modulated signal, and the preamble signal or the pilot training signal corresponding to different transmitter modulation methods is the same, that is, QPSK and GMSK can share the same preamble signal or pilot training signal, saving communication resources. However, the modulation method of the preamble signal or the pilot training signal is the same as the aforementioned transmitter modulation method, that is, if the transmitter modulation method is GMSK, the modulation method of the preamble signal or the pilot training signal also uses GMSK; if the transmitter modulation method is QPSK, the modulation method of the preamble signal or the pilot training signal also uses QPSK.

[0048] Reference Figure 2 , at step S102, the aforementioned modulated signal is subjected to synchronization processing and filtering processing to obtain a receiver synchronization signal. In practical applications, this step may include steps S1021 - S1023. At step S1021, a transmitter common synchronization header is inserted into the aforementioned modulated signal to generate a transmitter synchronization signal. In a real-time scenario, since the synchronization processing is for measuring the frequency offset and timing synchronization, this transmitter common synchronization header can use the GMSK modulation method or the QPSK modulation method, and either modulation method can be selected according to the actual situation during the operation process.

[0049] At step S1022, the synchronization signal of the transmitting end is filtered by a receiving-end filtering method corresponding to the aforementioned transmitting-end modulation method to obtain a filtered signal. For example, if the transmitting-end modulation method is GMSK, the receiving-end filtering method also adopts the filtering method of GMSK (such as low-pass filtering); if the transmitting-end modulation method is QPSK, the receiving-end filtering method also adopts the filtering method of QPSK (such as root-raised cosine filtering). In one embodiment, before the aforementioned filtering process, the synchronization signal of the transmitting end can also pass through low-pass filtering and then enter the filtering process through a time-varying multipath channel. At step S1023, the filtered signal is synchronously processed by a receiving-end common synchronization processing method corresponding to the common synchronization header shared by the transmitting end to obtain a receiving-end synchronization signal. For example, if the common synchronization header of the transmitting end adopts GMSK, the receiving-end common synchronization processing method also adopts GMSK; if the common synchronization header of the transmitting end adopts QPSK, the receiving-end common synchronization processing method also adopts QPSK. By making GMSK and QPSK share the same synchronization header at the transmitting end and the same synchronization processing method at the receiving end, the communication process is simplified.

[0050] At step S103, the receiving-end synchronization signal is pre-equalized by an equalization preprocessing method corresponding to the above-mentioned transmitting-end modulation method to obtain an equalization preprocessing signal. For example, if the transmitting-end modulation method is GMSK, its equalization preprocessing method includes, for example, parameter estimation of a memory channel, GMSK memory cancellation filtering, and GMSK multi-sampling point coherent demodulation; if the transmitting-end modulation method is QPSK, its equalization preprocessing method includes optimal sampling point extraction and phase correction. At step S104, the equalization preprocessing signal is frequency-domain equalized by a shared frequency-domain equalization method to obtain a soft output signal, so that GMSK and QPSK can share a frequency-domain equalization device.

[0051] At step S105, the soft output signal is decoded to obtain the source information sequence. In one embodiment, the decoding process of the soft output signal can include: demultiplexing the soft output signal by a shared demultiplexing method to obtain a demultiplexed signal; deinterleaving the demultiplexed signal by a shared deinterleaving method to obtain a deinterleaved signal; decoding the deinterleaved signal by a shared decoding method to obtain the source information sequence. GMSK and QPSK can share the same demultiplexing device, the same deinterleaving device, and the same decoding device, further saving costs.

[0052] Reference Figure 4 and Figure 5 , in order to verify the performance of GMSK and QPSK in the above communication method, Figure 4Additive white Gaussian noise simulation of GMSK and QPSK in the above communication method Figure 5 Simulations of GMSK and QPSK in a suburban channel. It can be seen from the bit error rate curves in the figure that both have reached the theoretical limit.

[0053] In a second aspect, referring to Figure 6 , the present application provides a communication device supporting GMSK and QPSK, including: a transmitter modulation module configured to select GMSK or QPSK as the transmitter modulation method to modulate the signal to be modulated according to the signaling configuration information generated by the network device to obtain a modulated signal, and in response to selecting GMSK as the transmitter modulation method, obtaining a linear expression of the signal to be modulated before modulating the signal to be modulated, where the signal to be modulated is obtained after pre-modulation processing of the source information sequence; a synchronization filtering module configured to perform synchronization processing and filtering processing on the modulated signal to obtain a receiver synchronization signal; an equalization preprocessing module configured to perform equalization preprocessing on the receiver synchronization signal through an equalization preprocessing method corresponding to the transmitter modulation method to obtain an equalization preprocessing signal; a frequency-domain equalization processing module configured to perform frequency-domain equalization processing on the equalization preprocessing signal through a common frequency-domain equalization method to obtain a soft output signal; and a decoding module configured to perform decoding processing on the soft output signal to obtain the source information sequence; the transmitter modulation module, the synchronization filtering module, the equalization preprocessing module, the frequency-domain equalization processing module, and the decoding module are connected in sequence. By adopting this embodiment, the advantages of long transmission distance of GMSK and high spectral efficiency of QPSK are fully utilized, and two communication methods can be realized by the same device, saving costs.

[0054] The implementation process of the embodiment of the present application can be as follows: First, a source information sequence is generated by a source pseudo-random sequence generator, which can be a binary sequence. After the source information sequence undergoes channel coding, interleaving, and burst data generation processes, it is selected to be modulated by GMSK or QPSK according to the signaling configuration information. If it is GMSK, a sample sequence of high-speed GMSK is formed. If it is the QPSK method, QPSK modulation is used. The channel pilot of each data block of the source information sequence is consistent with its own modulation method, which is convenient for ensuring the accuracy and consistency of subsequent channel estimation.

[0055] The periodic transmit - end common synchronization headers can all adopt the GMSK modulation method. In this way, the synchronization processing at the receive - end can be the same processing module, and GMSK and QPSK share the synchronization processing here. Since the purpose of the synchronization header is to measure the frequency offset and perform timing synchronization, either of the two modulation methods can be selected to complete the synchronization processing. The transmit filters of GMSK and QPSK are different. QPSK uses an RRC filter, and the GMSK filter uses Gaussian filtering. Before signal transmission, GMSK and QPSK can share a common low - pass filtering processing module. After filtering, the GMSK and QPSK sequences pass through a time - varying multipath channel and then Gaussian white noise is added and sent to the receive filter for filtering. The output sample sequence after the receive - end filtering processing does not undergo downsampling, only noise and spurs are filtered out, and the rate is not reduced. Then, high - precision synchronization is performed to complete timing and frequency - offset measurement and frequency - offset correction. After the synchronization processing is completed, GMSK and QPSK perform their respective channel estimations. After obtaining their respective channel - estimation signals, they enter a unified equalization pre - processing module, and subsequent de - interleaving and decoding are all processed by a unified module. For the same bandwidth, the information rate of QPSK is twice as high. Two high - speed communications are implemented with the same architecture. GMSK can transmit farther, and QPSK has higher transmission efficiency.

[0056] The processing flow of the equalization pre - processing module is as follows: If it is GMSK, first, parameter estimation of the memory channel, GMSK memory cancellation filtering, and GMSK multi - sampling - point coherent demodulation are required. At this time, the high - speed signal becomes the physical - layer base - band rate, and the difference multiple IPOINT = 4 / 8. If it is QPSK, after timing synchronization, first, the optimal sampling - point extraction and phase correction are performed. The synchronization, parameter estimation of the memory channel, and memory cancellation filtering in the GMSK system are carried out in two steps. To complete the memory cancellation filtering, the GMSK synchronization processing and channel estimation must be carried out first. The parameter estimation of the memory channel and memory cancellation filtering both take the received signal r as the input, where r is the sampling sequence of the received GMSK burst signal. The definition of the oversampling factor OSR is f s / r b ,where f s is the sampling frequency, r b is the symbol rate, and L hIt represents the expected length of the channel impulse response, with the unit of bit time. The channel estimator inputs the channel impulse response h into the memory cancellation filter and simultaneously transmits the burst position in the estimated received signal r. Synchronization is obtained based on the correlation characteristics of the training sequence. In the subsequent process, the frequency domain equalization device can be shared by GMSK and QPSK. The frequency domain equalization removes the inter-symbol interference of the received signal, and then the obtained soft output is demultiplexed, deinterleaved, and decoded by the channel LDPC (Low Density Parity Check Code), and the transmitted information can be restored to complete the entire process of information transmission.

[0057] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. The same components are denoted by the same reference numerals. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A communication method supporting GMSK and QPSK, characterized in that, Including the following steps: According to the signaling configuration information generated by the network device, select GMSK or QPSK as the modulation method at the sending end to modulate the signal to be modulated, so as to obtain the modulated signal, and in response to selecting GMSK as the modulation method at the sending end, obtain the linear expression of the signal to be modulated before modulating the signal to be modulated, and the signal to be modulated is obtained after pre-modulation processing of the source information sequence; In response to selecting the QPSK method, perform QPSK modulation; Perform synchronization processing and filtering processing on the modulated signal to obtain the synchronization signal at the receiving end; Perform equalization preprocessing on the synchronization signal at the receiving end through the equalization preprocessing method corresponding to the modulation method at the sending end to obtain the equalization preprocessing signal; If the modulation method at the sending end is GMSK, the equalization preprocessing method includes parameter estimation of the memory channel, GMSK memory cancellation filtering, and GMSK multi-sampling point coherent demodulation; If the modulation method at the sending end is QPSK, the equalization preprocessing method includes optimal sampling point extraction and phase correction; Perform frequency-domain equalization processing on the equalization preprocessing signal through a common frequency-domain equalization method to obtain a soft output signal; the frequency-domain equalization removes the inter-symbol interference of the received signal; Perform decoding processing on the soft output signal to obtain the source information sequence.

2. The communication method according to claim 1, wherein Performing decoding processing on the soft output signal includes: demultiplexing the soft output signal through a common demultiplexing method to obtain a demultiplexed signal.

3. The communication method according to claim 2, wherein Performing decoding processing on the soft output signal further includes: deinterleaving the demultiplexed signal through a common deinterleaving method to obtain a deinterleaved signal.

4. The communication method according to claim 3, wherein Performing decoding processing on the soft output signal further includes: decoding the deinterleaved signal through a common decoding method to obtain the source information sequence.

5. The communication method according to any one of claims 1-4, characterized in that, Performing synchronization processing and filtering processing on the modulated signal includes: Inserting a common synchronization header at the sending end into the modulated signal to generate a synchronization signal at the sending end; Performing filtering processing on the synchronization signal at the sending end through a receiving-end filtering method corresponding to the modulation method at the sending end to obtain a filtered signal; Performing synchronization processing on the filtered signal through a receiving-end common synchronization processing method corresponding to the common synchronization header at the sending end to obtain a synchronization signal at the receiving end.

6. The communication method according to claim 5, wherein The common synchronization header at the sending end uses the GMSK modulation method or the QPSK modulation method; if the common synchronization header at the sending end uses GMSK, the receiving-end common synchronization processing method also uses GMSK; If the common synchronization header at the sending end uses QPSK, the receiving-end common synchronization processing method also uses QPSK.

7. The communication method according to any one of claims 1-4, characterized in that, The linear expression of the signal to be quasi-modulated is as follows: where I k is the data after differential encoding of the source information sequence, j k is the k-th power of the imaginary number, and C0(t - kT) is the time-limited amplitude modulation pulse.

8. The communication method according to any one of claims 1-4, characterized in that It also includes: Adding a preamble signal or a pilot training signal to the modulated signal, and the preamble signal or the pilot training signal corresponding to different modulation methods at the sending end is the same.

9. The communication method according to claim 8, wherein The modulation method of the preamble signal or the pilot training signal is the same as the modulation method at the sending end.

10. A communication device supporting GMSK and QPSK, characterized in that, Including: A transmitting - end modulation module, which is configured to select GMSK or QPSK as the transmitting - end modulation method to modulate a signal to be modulated according to the signaling configuration information generated by a network device, so as to obtain a modulated signal. And in response to selecting GMSK as the transmitting - end modulation method, a linear expression of the signal to be modulated is obtained before modulating the signal to be modulated, where the signal to be modulated is obtained after pre - modulation processing of a source information sequence; in response to selecting the QPSK method, QPSK modulation is adopted. A synchronization filtering module, which is configured to perform synchronization processing and filtering processing on the modulated signal to obtain a receiving - end synchronization signal. An equalization pre - processing module, which is configured to perform equalization pre - processing on the receiving - end synchronization signal through an equalization pre - processing method corresponding to the transmitting - end modulation method to obtain an equalization pre - processed signal. If the transmitting - end modulation method is GMSK, the equalization pre - processing method includes parameter estimation of a memory channel, GMSK memory cancellation filtering, and GMSK multi - sampling - point coherent demodulation. If the transmitting - end modulation method is QPSK, the equalization pre - processing method includes optimal sampling - point extraction and phase correction; A frequency - domain equalization processing module, which is configured to perform frequency - domain equalization processing on the equalization pre - processed signal through a common frequency - domain equalization method to obtain a soft - output signal; the frequency - domain equalization removes inter - symbol interference of the received signal. And A decoding module, which is configured to perform decoding processing on the soft - output signal to obtain the source information sequence. The transmitting - end modulation module, the synchronization filtering module, the equalization pre - processing module, the frequency - domain equalization processing module, and the decoding module are connected in sequence.

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