A wireless audio and video communication method based on polarization code

Abstract

The invention discloses a wireless audio and video communication method based on polarization code, which belongs to the field of wireless communication technology. The method mainly includes the steps of source coding, polarization code coding, modulation, transmission and reception, demodulation, polarization code decoding and source decoding. The method first converts analog audio and video signals into digital signals by frequency sampling, quantization and encoding audio and video signals. Then, the source coded data is further encoded using polarization code. The coded data is then modulated onto a carrier and sent through a wireless device. After receiving the signal, the receiving end demodulates and decodes it using the corresponding polarization code, and finally performs source decoding to restore the original audio and video stream. This method improves the quality and efficiency of audio and video data transmission, enhances the anti-interference ability and error correction ability of the signal, is simple to implement, and is conducive to the application and development of wireless audio and video communication technology.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communications, and more specifically relates to a wireless audio and video communication method based on polarization codes. Background Art

[0002] Wireless audio and video communication technology is an important part of modern communication networks. It allows users to receive and send audio and video information in a wireless network environment, greatly promoting the popularization and application of mobile Internet. However, due to various factors in the wireless transmission process, such as channel noise, interference, signal attenuation, etc., errors may occur in the transmitted audio and video data, thereby reducing the transmission quality and user experience.

[0003] To solve this problem, coding technology has been introduced to improve the error tolerance of transmission. The basic idea of ​​coding technology is to add redundancy to the source data, so that even if there are some errors in the data received by the receiving end, the redundant information can be used to correct the errors, thereby improving the reliability of data transmission. Currently, the most widely used coding technologies include Turbo codes and Low-Density Parity-Check (LDPC) codes, which have made great contributions to improving the reliability of data transmission. However, these traditional coding technologies are often complex to implement and are not easy to apply in large-scale industrial applications.

[0004] Polar code is a new channel coding technology proposed by Professor Erdal Arikan in 2008. The theoretical performance of polar code is close to the Shannon limit, and the encoding and decoding algorithm is relatively simple, which is suitable for the implementation of large-scale integrated circuits. Therefore, polar code is considered to be an important candidate technology for future wireless communication standards. However, due to the imperfect theory of polar code, there is a certain gap between theory and practical application. How to effectively apply polar code to the field of wireless audio and video communication still needs further research. Summary of the invention

[0005] The present invention proposes a wireless audio and video communication method based on polarization code, which mainly reduces signal interference by using polarization code and OCT precoding, improves anti-interference ability and error correction ability, and ensures the integrity and quality of audio and video data during wireless transmission. It aims to improve the reliability and quality of wireless audio and video data transmission, thereby enhancing the user's audio and video receiving experience.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: the method comprises:

[0007] Source coding: At the communication source, the audio and video streams are first encoded to convert analog signals into digital signals.

[0008] Polar code encoding: polar code is used to further encode the source coded data to improve its anti-interference and error correction capabilities;

[0009] Modulation, modulating the coded data onto a carrier for transmission over a wireless channel;

[0010] Sending and receiving: The modulated signal is sent out through the wireless transmitting device, and the wireless receiving device receives the sent signal at the communication destination;

[0011] Demodulation, demodulating the received signal and separating it from the carrier;

[0012] Polar code decoding, using the polar code corresponding to the source end to decode the demodulated data;

[0013] Source decoding further decodes the decoded data to restore the original audio and video stream.

[0014] In one embodiment, the source code includes:

[0015] Frequency sampling of audio and video signals, with the sampling frequency at least twice the highest frequency of the signal, to ensure the integrity of the signal information;

[0016] The conversion of a continuous analog signal into a discrete digital signal is performed using a quantizer, whose job is to round off each sample value of the input signal to the nearest predefined discrete value;

[0017] Encode the quantized discrete digital signal and convert the discrete value into binary code.

[0018] In one solution, the polar code encoding adopts OCT precoding, which can equalize the OFDM subcarrier channel conditions. It is placed after the modulation symbols are mapped to the data subcarriers and before the inverse fast Fourier transform; an orthogonal cyclic matrix is ​​used to evenly distribute the noise to all data subcarriers by performing matrix multiplication with the modulation symbols on the data subcarriers.

[0019] In one solution, the polar code decoding adopts a one-to-one mapping method between the polar code encoder and the data subcarrier.

[0020] In one solution, the modulation adopts QAM modulation, which changes the amplitude and phase of the carrier signal to achieve information transmission, and performs 64-QAM mapping, where one symbol contains 4 bits or 6 bits of information.

[0021] In one solution, the orthogonal cyclic matrix used in the OCT precoding is generated by a Zadoff-Chu sequence, and the ZC sequence has an ideal periodic autocorrelation;

[0022] The ZC sequence has an autocorrelation with itself, which is equal to the energy of the sequence. Its autocorrelation with other time-shifted sequences is equal to 0.

[0023] A ZC sequence is represented as ,and represents a time shift of p positions to the right, then the periodic autocorrelation is expressed as:

[0024]

[0025] Among them, ()* represents the conjugate symmetry operation on the matrix, E represents the sequence energy; OFDM with data subcarriers;

[0026] First design , so that its sequence energy is equal to ;

[0027] Based on the ZC sequence, an orthogonal circulant matrix F is constructed to satisfy:

[0028]

[0029] Each row in is a time-shifted version of the ZC sequence;

[0030] Based on its orthogonality, satisfy ;in, yes The identity matrix of .

[0031] In one solution, the polar code decoding maps a symbol modulated by a codeword to a unique corresponding data subcarrier;

[0032] A series of continuous modulation symbols are loaded into different time domains, and the order reflected on the data subcarriers is ; Independent encoding and decoding for each data subcarrier can effectively ensure that the polarization code codeword experiences a single channel condition, thereby ensuring the decoding performance of the polarization code.

[0033] Beneficial effects of the present invention:

[0034] Through polarization code and OCT precoding, the noise is evenly distributed to all data subcarriers, which greatly improves the data quality of wireless audio and video communications and enables the receiving end to more accurately restore the original audio and video stream.

[0035] The use of QAM modulation can more effectively utilize frequency resources and improve transmission efficiency. In addition, the symbol modulated by a codeword is mapped to the only corresponding data subcarrier, which effectively ensures that the polarization codeword experiences a single channel condition, further improving the transmission efficiency.

[0036] Polar codes are used to encode data, which enhances resistance to signal interference and provides error correction capabilities, reducing data errors and losses during transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of the method of the present invention;

[0038] Figure 2 is the position in the OCT precoding data processing flow of the present invention;

[0039] Figure 3 The data subcarrier mapping diagram of the present invention and the traditional data subcarrier mapping diagram. DETAILED DESCRIPTION

[0040] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0041] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0042] like Figure 1 As shown, the wireless audio and video communication method based on polarization code includes:

[0043] S1, source coding, at the communication source end, first encode the audio and video streams to convert analog signals into digital signals. Audio and video source coding includes the following steps:

[0044] Audio and video signals are frequency sampled. The basic principle is that the sampling frequency should be at least twice the highest frequency of the signal to ensure the integrity of the signal information. This is called the Nyquist theorem. Video signals are usually sampled at different frequencies than audio signals. Audio is usually sampled at 44.1kHz or 48kHz, while video signals are sampled at 25, 30, or 60 frames per second.

[0045] Quantization is the process of converting a continuous analog signal into a discrete digital signal, which is usually performed using a quantizer. The job of a quantizer is to round each sample value of the input signal to the nearest predefined discrete value.

[0046] Encoding a quantized discrete digital signal. This process usually converts the discrete values ​​into binary codes so that they can be processed and transmitted on computer systems and digital communication networks.

[0047] S2, polarization code encoding, uses polarization code to further encode the source coded data to improve its anti-interference and error correction capabilities.

[0048] The polar code encoding adopts OCT precoding, which can balance the OFDM subcarrier channel conditions. It is placed after the modulation symbols are mapped to the data subcarriers and before the inverse fast Fourier transform. An orthogonal cyclic matrix is ​​used to evenly distribute the noise to all data subcarriers by performing matrix multiplication with the modulation symbols on the data subcarriers.

[0049] OCT precoding is a precoding technology that can balance the OFDM subcarrier channel conditions. Figure 2 As shown in the figure, it is after the modulation symbols are mapped to the data subcarriers and before the Inverse Fast Fourier Transform (IFFT). In simple terms, it uses an orthogonal cyclic matrix to evenly distribute the noise to all data subcarriers by performing matrix multiplication with the modulation symbols on the data subcarriers. Next, the implementation principle of OCT precoding is briefly introduced.

[0050] The orthogonal cyclic matrix used in OCT precoding is generated by the Zadoff-Chu sequence. The ZC sequence has an ideal periodic autocorrelation. In other words, the ZC sequence has an autocorrelation with itself (time shift is 0) that is equal to the energy of the sequence, and the autocorrelation with other time-shifted sequences of itself is also equal to 0.

[0051] Assume a ZC sequence is represented as ,and represents a time shift of p positions to the right, then the periodic autocorrelation is expressed as:

[0052] (1)

[0053] Among them, ()* represents the conjugate symmetry operation on the matrix, E represents the sequence energy; OFDM with data subcarriers;

[0054] First design , so that its sequence energy is equal to ;

[0055] Based on the ZC sequence, an orthogonal circulant matrix F is constructed to satisfy:

[0056] (2)

[0057] Each row in is a time-shifted version of the ZC sequence;

[0058] Based on its orthogonality, that is, formula (1), satisfy ;in, yes The identity matrix of .

[0059] Assuming that in OFDM There is a corresponding 1NC modulation symbol vector on each data subcarrier. , after channel transmission, at the receiving end, the noise on all subcarriers is expressed as The noise vector, Then, the modulation symbol vector on the received data subcarrier is expressed as Then, OCT precoding converts the corresponding modulation symbols and matrices on the data subcarriers Do the multiplication and we get . Then, Loaded onto the data subcarrier for IFFT. Therefore, after OCT precoding, the actual transmission is Correspondingly, the modulation symbol vector received at the receiving end is At the receiving end, in order to restore the modulation symbol , after performing the fast Fourier transform, Perform matrix multiplication with F* to perform OCT decoding, that is,

[0060] (3)

[0061] because The periodic orthogonality of X is successfully restored. After being balanced The subcarrier noise vector, which can be expressed as

[0062] (4)

[0063] for Each element of contains the original subcarrier noise , and are respectively the elements of the ZC sequence Weighted. Because each element of the ZC sequence has the same modulus, Each element of the noise on each subcarrier has the same energy. Therefore, the data on each data subcarrier is basically damaged by the noise to the same extent. The noise on the subcarrier is equalized to a stable level.

[0064] S3, modulation, modulates the encoded data onto a carrier for transmission in a wireless channel.

[0065] The modulation adopts QAM modulation, which changes the amplitude and phase of the carrier signal to achieve information transmission, and performs 64-QAM mapping, where one symbol contains 4 bits or 6 bits of information.

[0066] The specific implementation process is as follows:

[0067] Choosing a carrier wave: For transmission in the radio spectrum, the frequency of the carrier wave may range from tens of kilohertz to several gigahertz.

[0068] Modulate the carrier: For QAM (Quadrature Amplitude Modulation) modulation, the amplitude and phase of the carrier signal are changed simultaneously to achieve information transmission. Generally, higher-order mapping is performed, such as 16-QAM or 64-QAM, and one symbol contains 4 bits or 6 bits of information.

[0069] During the modulation process, the source data is converted into changes in carrier frequency (frequency shift keying, FSK) and carrier amplitude according to preset rules. For complex modulation such as QAM, the amplitude and phase of the carrier are changed at the same time.

[0070] Sending signal: The modulated carrier signal is sent to the wireless transmission medium, such as the air, through a wireless device, such as an antenna. In this process, the wireless device converts the electrical signal into an electromagnetic wave signal and then releases it into the air.

[0071] S4. Sending and receiving: The modulated signal is sent out through the wireless transmitting device, and at the communication destination, the wireless receiving device receives the sent signal.

[0072] The sending process is as follows:

[0073] The modulated signal is first sent to a power amplifier for amplification. This is because wireless signals will be lost during propagation, so sufficient power is required when transmitting.

[0074] The power-amplified signal is sent to the transmitting antenna. The antenna converts the electrical signal into electromagnetic waves and transmits them into the air. In this process, the transmitting antenna acts as a radiator.

[0075] The receiving process is as follows:

[0076] At the receiving end, the receiving antenna captures the incoming electromagnetic waves and converts them into electrical signals. In this process, the receiving antenna acts as a receiver.

[0077] The electrical signal is initially amplified by a low noise amplifier (LNA), and then restored from the carrier frequency to the baseband frequency by a mixer and a local oscillator.

[0078] The baseband signal goes through a series of demodulation and decoding processes to restore the original information.

[0079] S5. Demodulation: demodulate the received signal and separate it from the carrier.

[0080] When electromagnetic wave signals transmitted through the air are received wirelessly, receiving devices such as antennas convert these electromagnetic wave signals back into electrical signals.

[0081] The received signal is usually weak, so it needs to be initially amplified by a low noise amplifier (LNA). A mixer and a local oscillator are used here to reduce the received high-frequency signal to the baseband frequency for further processing.

[0082] After reducing the frequency to the baseband frequency, demodulation is performed. Depending on the modulation method of the transmitter, the corresponding demodulation technology is selected. For QAM modulation, it is necessary to combine the changes in signal amplitude and phase to obtain the original information.

[0083] Symbol decoding: According to the demodulated signal value, it is mapped back to the corresponding binary signal. The sequence of these binary signals forms the required original data.

[0084] S6: Polarization code decoding: using the polarization code corresponding to the source end to decode the demodulated data.

[0085] The polarization code decoding adopts a one-to-one mapping method between the polarization code encoder and the data subcarrier. The polarization code decoding maps a symbol modulated by a codeword to a unique corresponding data subcarrier.

[0086] The traditional data subcarrier mapping method loads this series of continuous modulation symbols onto the data subcarrier in the following order: .

[0087] like Figure 3As shown in (a), the modulation symbols are placed on each data subcarrier one by one, that is, they are evenly dispersed in the frequency domain. For the application of polarization codes, if there is no frequency fading effect in the communication system, then this method is feasible. To achieve high-speed information transmission, it is inevitable to exceed the modulation bandwidth of devices such as LEDs and photodiodes (PDs), thereby causing frequency fading effects. This data subcarrier mapping method will make the codeword of each polarization code

[0088] Experience different subcarrier channel environments. If a codeword that has experienced multiple channel environment conditions is received, the uncertainty of the channel conditions will make it difficult to accurately calculate the LLR. The LLR calculated by the mismatched channel conditions will undoubtedly affect the decoding performance of the polarization code. In fact, technologies such as subcarrier interleaving can reduce the mismatch effect of the diversified subcarrier channels caused by frequency fading on the polarization code. This application proposes a

[0089] A simple data subcarrier mapping method is proposed to avoid this mismatch.

[0090] like Figure 3 As shown in (b), a symbol modulated by a codeword is mapped to a unique corresponding data subcarrier. In other words, a series of continuous modulation symbols are loaded into different time domains, and the order reflected on the data subcarrier is ; Performing independent encoding and decoding for each data subcarrier can effectively ensure that the polarization code codeword experiences a single channel condition and ensure the decoding performance of the polarization code. Although this method associates the data of a polarization code codeword with a subcarrier, it is not necessary to construct different polarization codes for each subcarrier in different channel environments.

[0091] S7, source decoding, further decodes the decoded data to restore the original audio and video stream.

[0092] Source decoding is the process of converting the received data from the encoded signal back to the original audio and video signal. The specific implementation process is as follows:

[0093] Demodulating the coded data we need from the modulated signal is a step that accompanies the previous signal decoding process.

[0094] The coded data obtained by demodulation is decoded using an error correction code to repair errors that may have occurred during the transmission process and restore the original coded data.

[0095] The key step of converting the encoded signal for transmission back into audio and video streams. For video signals, encoding standards such as H.264, H.265, and VP9 are used, and the corresponding decoder needs to be selected for decoding.

[0096] The digitized sample values ​​obtained after decompression are operated according to the original sampling rate and quantization parameters to restore the original signal. The digitized signal obtained above is converted from digital to analog to restore it to an analog signal. The audio and video are processed synchronously to ensure the synchronization of sound and picture.

[0097] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM).

[0098] It should be understood that the detailed description of the technical solutions of the present invention by means of the preferred embodiments is illustrative rather than restrictive. A person skilled in the art may modify the technical solutions described in the embodiments, or replace some of the technical features by equivalents, based on reading the specification of the present invention; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wireless audio and video communication method based on polarization codes, characterized in that: The method includes: Source coding: At the communication source, the audio and video streams are first encoded to convert analog signals into digital signals. The source code includes: Frequency sampling of audio and video signals with a sampling frequency at least twice the highest frequency of the signal; The conversion of a continuous analog signal into a discrete digital signal is performed using a quantizer, whose job is to round off each sample value of the input signal to the nearest predefined discrete value; Encode the quantized discrete digital signal and convert the discrete value into binary code; Polar code encoding: polar code is used to further encode the source coded data to improve its anti-interference and error correction capabilities; The polar code encoding adopts OCT precoding, which can balance the OFDM subcarrier channel conditions. It is after the modulation symbol is mapped to the data subcarrier and before the inverse fast Fourier transform. It uses an orthogonal cyclic matrix to evenly distribute the noise to all data subcarriers by performing matrix multiplication with the modulation symbol on the data subcarrier. The orthogonal cyclic matrix used in the OCT precoding is generated by a Zadoff-Chu sequence, and the ZC sequence has an ideal periodic autocorrelation; The ZC sequence has an autocorrelation with itself, which is equal to the energy of the sequence. Its autocorrelation with other time-shifted sequences is equal to 0. A ZC sequence is represented as ,and represents a time shift of p positions to the right, then the periodic autocorrelation is expressed as: ; Among them, ()* represents the conjugate symmetry operation on the matrix, E represents the sequence energy; OFDM with data subcarriers; First design , so that its sequence energy is equal to ; Based on the ZC sequence, an orthogonal circulant matrix F is constructed to satisfy: ; Each row in is a time-shifted version of the ZC sequence; Based on its orthogonality, satisfy ;in, yes The identity matrix of Modulation, modulating the coded data onto a carrier for transmission over a wireless channel; The modulation adopts QAM modulation, changes the amplitude and phase of the carrier signal to realize the transmission of information, performs 64-QAM mapping, and one symbol contains 4 bits or 6 bits of information; Sending and receiving: The modulated signal is sent out through the wireless transmitting device, and the wireless receiving device receives the sent signal at the communication destination; Demodulation, demodulating the received signal and separating it from the carrier; Polar code decoding, using the polar code corresponding to the source end to decode the demodulated data; Source decoding further decodes the decoded data to restore the original audio and video stream.

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