Patent Description:
In the prior art, most modulation technologies (for example, conventional quadrature amplitude modulation (Quadrature Amplitude Modulation, QAM for short)) are modulation technologies that have a same constellation symbol probability and that are designed without considering constraint conditions such as a noise distribution and a power limitation. In such modulation technologies, a channel capacity is insufficient or bit error rate performance is not good when there are input amplitude constraints or different noise distributions.

Document <NPL>, describes a different modulation methods for wireless telecommunication technology.

Document <CIT> describes a transmission of data over a plastic optical fibre.

Embodiments of this application provide a data transmission method and apparatus based on probability non-uniform modulation, to improve transmission efficiency of data on which probability non-uniform modulation is performed. The present invention is defined by the attached set of claims.

In the descriptions of this application, unless otherwise specified, "/" means "or". For example, A/B may represent A or B. The term "and/or" in this specification describes only an association relationship for associated objects and represents that three relationships may exist. In addition, "a plurality of" means two or more than two. Words such as "first" and "second" do not limit a quantity and an execution sequence, and words such as "first" and "second" are not necessarily different.

To make the following descriptions clearer, the following briefly describes some concepts in this application.

A modulation scheme may also be referred to as a modulation type, and is a modulation scheme used when a coded bit (or a coded bit stream) is modulated. For example, the modulation scheme may be QAM, quadrature phase shift keying (Quadrature Phase Shift Keying, QPSK for short) modulation, pulse amplitude modulation (Pulse Amplitude Modulation, PAM for short), or the like.

A constellation symbol is a modulation symbol obtained by modulating a coded bit (or a coded bit stream).

A bit quantity corresponding to the constellation symbol may also be described as a quantity of bits carried or included in the constellation symbol, and is a bit quantity of coded bits (or coded bit streams) corresponding to the constellation symbol. Coded bits (or coded bit streams) corresponding to a constellation symbol are modulated or mapped to obtain the constellation symbol.

A modulation order is a quantity of constellation symbol types.

A probability of a constellation symbol is a theoretical proportion of the constellation symbol in a constellation symbol set. For example, if a theoretical proportion of a constellation symbol S<NUM> in a constellation symbol set is <NUM>/<NUM>, a probability of the constellation symbol is <NUM>/<NUM>. When probabilities of a plurality of types of constellation symbols are the same, the constellation symbols may be referred to as probability uniform constellation symbols. When probabilities of at least two types of constellation symbols in the plurality of types of constellation symbols are different, the constellation symbols may be referred to as probability non-uniform constellation symbols. The probability non-uniform constellation symbol may be obtained after a non-equal-length mapper or a probability non-uniform mapper modulates or maps coded bits (or a coded bit stream).

A probability of a coded bit is a theoretical proportion of a coded bit with a specific value in a coded bit stream. For example, if a theoretical proportion of a coded bit whose value is <NUM> in a coded bit stream is <NUM>/<NUM>, a probability of the coded bit is <NUM>/<NUM>. When probabilities of coded bits with different values are the same, the coded bits may be referred to as equal-probability coded bits; otherwise, the coded bits may be referred to as non-equal-probability coded bits. Usually, a coded bit stream obtained after channel coding is performed on an original equal-probability bit stream is also an equal-probability coded bit stream. The original bit stream may be a bit stream obtained after source coding.

With development of Internet applications, novel applications such as virtual reality (Virtual Reality, VR for short), augmented reality (Augmented Reality, AR for short), and an ultra high-definition video (Ultra High-Definition Video, UHDV for short), the Internet of Vehicles, and the Internet of Things have higher requirements on performance indicators such as a communication transmission rate, a communication delay, and power consumption. To meet communication requirements of these applications, a plurality of types of wireless technologies such as a new multiple access technology, a new waveform technology, a new modulation scheme, a new coding scheme, a large-scale antenna array, full-spectrum access, and a heterogeneous network are proposed.

Compared with the previous-generation Institute of Electrical and Electronics Engineers (Institute of Electrical and Electronics Engineers, IEEE for short) <NUM>. <NUM> ad standard, the IEEE <NUM>. 11ay standard have a key technical point of proposing a non-uniform constellation (Non-uniform Constellation) modulation technology. The non-uniform constellation modulation technology is a modulation scheme in which probabilities of constellation symbols are the same and constellation symbol spacings (that is, Euclidean distances, Euclidean Distances) are different. In a conventional modulation scheme in which constellation symbols have a same probability, a plurality of equal-probability coded bits may be mapped to one constellation symbol, there may be a plurality of types of constellation symbols, and probabilities of the plurality of types of constellation symbols are the same.

Due to various types of noise existing at a receive end, an average power constraint at a transmit end, an amplitude constraint of an input signal, and the like, an optimal signal whose transmission rate can achieve a channel capacity is a discrete probability non-uniform constellation symbol. Then the constellation symbol is demodulated in combination with a maximum a posteriori (Maximum a Posteriori, MAP for short) estimation algorithm to achieve a relatively ideal shaping gain and relatively ideal bit error rate performance. Therefore, probability nonuniform modulation is proposed. Probability non-uniform modulation is a modulation scheme in which probabilities of constellation symbols are different, and constellation symbol spacings may be the same or may be different. In a probability non-uniform modulation scheme, a plurality of equal-probability coded bits may be mapped to one constellation symbol, there may be a plurality of types of constellation symbols, and probabilities of at least two types of constellation symbols in the plurality of types of constellation symbols are different. Compared with a conventional probability uniform modulation technology, a probability non-uniform modulation technology can obtain a better shaping gain (Shaping gain), and has better robustness against non-ideal interference such as phase noise (Phase Noise) and quantization noise (Quantization Noise).

Currently, researches on probability non-uniform modulation are all theoretical researches. In probability non-uniform modulation, because probabilities of constellation symbols are different, a demodulation algorithm of a conventional maximum likelihood (Maximum Likelihood) estimation algorithm based on an assumption that prior probabilities of constellation symbols are same is no longer applicable. A demodulator at the receive end needs to know information such as a probability of each constellation symbol and a modulation order for probability non-uniform modulation, so that the demodulator can demodulate the constellation symbols based on the MAP estimation algorithm.

For clearer understanding of this application, the following briefly describes a principle of probability non-uniform modulation.

Before probability non-uniform modulation is performed, a plurality of bit stream groups may be set, one bit stream group includes one or more bit streams, and one bit stream includes one or more bits. Abit stream in each bit stream group may be mapped to one constellation symbol. Probabilities of constellation symbols to which bit streams in at least two bit stream groups are mapped are different.

In one case, bit streams in the plurality of bit stream groups include a same quantity of bits. For example, referring to <FIG>, in case <NUM>, three bit stream groups [<NUM>], [<NUM>, <NUM>], and [<NUM>] are set. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. In case <NUM>, three bit stream groups [<NUM>, <NUM>], [<NUM>], and [<NUM>] are set. A constellation symbol to which [<NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. In case <NUM>, three bit stream groups [<NUM>, <NUM>], [<NUM>, <NUM>, <NUM>], and [<NUM>, <NUM>, <NUM>] are set. A constellation symbol to which [<NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>, <NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>, <NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. In case <NUM>, three bit stream groups [<NUM>, <NUM>, <NUM>, <NUM>, [<NUM>, <NUM>, <NUM>], and [<NUM>] are set. A constellation symbol to which [<NUM>, <NUM>, <NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>, <NUM>, <NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>.

In another case, bit streams in the plurality of bit stream groups include different quantities of bits. For example, referring to <FIG>, three bit stream groups [<NUM>], [<NUM>], and [<NUM>] are set. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. In this case, for locations of the constellation symbols in a constellation diagram, refer to <FIG>.

Referring to <FIG>, nine bit stream groups [<NUM>], [<NUM>], [<NUM>], [<NUM>], [<NUM>], [<NUM>], [<NUM>], [<NUM>], and [<NUM>] are set. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p(S<NUM>) = <NUM>/<NUM>. A constellation symbol to which [<NUM>] is mapped is S<NUM>, and a probability of S<NUM> is p (S<NUM>) = <NUM>/<NUM>. In this case, for locations of the constellation symbols in a constellation diagram, refer to <FIG>.

Based on the example shown in <FIG>, if a bit stream is <NUM>, the first bit <NUM> may be mapped to S<NUM>, the second and third bits <NUM> may be mapped to S<NUM>, the fourth bit <NUM> may be mapped to S<NUM>, and the fifth and sixth bits <NUM> may be mapped to S<NUM>. In this case, constellation symbols in a constellation symbol set obtained by mapping <NUM> are S<NUM>, S<NUM>, S<NUM>, and S<NUM>.

In the description of the principle part of probability non-uniform modulation, the bits in the bit stream may be equal-probability coded bits on which channel coding is performed. The constellation symbol may be a constellation symbol in a PAM constellation symbol set.

The following briefly describes a data processing process at each of a transmit end and a receive end.

As shown in <FIG>, at the transmit end, an original bit stream is channel coded by a channel encoder to obtain a coded bit stream, and the coded bit stream is mapped by a mapper to obtain a constellation symbol. At the receive end, a demodulator demodulates the constellation symbol to obtain a coded bit stream, and a decoder decodes the coded bit stream to obtain the original bit stream. A probability non-uniform constellation symbol in this embodiment of this application may be generated in any one of manner <NUM> to manner <NUM>.

Manner <NUM>: Referring to <FIG>, an original bit stream is channel coded by an equal-probability channel encoder to obtain an equal-probability coded bit stream, and the equal-probability coded bit stream is mapped by a non-equal-length Huffman (Huffman) mapper, to generate a probability non-uniform constellation symbol. The demodulator at the receive end demodulates the probability non-uniform constellation symbol based on a learned complete structure of the non-equal-length Huffman mapper to obtain an equal-probability coded bit stream, and the equal-probability coded bit stream is decoded by a channel decoder to obtain the original bit stream.

In this manner, constellation symbols with different modulation orders and frequency band efficiency can be generated relatively flexibly, and a larger shaping gain can be obtained compared with a conventional probability uniform modulation scheme. In this manner, to ensure the shaping gain, a joint source-channel decoding (Joint Source-Channel Decoding, JSCD for short) algorithm may be used to decode the equal-probability coded bit stream.

Manner <NUM>: Referring to <FIG>, at the transmit end, an original bit stream is channel coded by a multi-level coder (Multi-level Coding, MLC for short) to obtain an equal-probability coded bit stream, and the equal-probability coded bit stream is mapped by a deterministic (deterministic) equal-length mapper, to generate a probability non-uniform constellation symbol. At the receive end, a multi-level decoder (Multi-level Decoding, MSD for short) performs multi-level decoding is performed on the probability non-uniform constellation symbol to obtain the original bit stream.

Manner <NUM>: Referring to <FIG>, at the transmit end, an original bit stream is channel coded by a single-level coder (Single-level Coding, SLC for short) to obtain an equal-probability coded bit stream, and the equal-probability coded bit stream is mapped by a deterministic equal-length mapper, to generate a probability non-uniform constellation symbol. At the receive end, a joint demapping decoder (Joint Demapping-decoding, JDD for short) demodulates and decodes the probability non-uniform constellation symbol to obtain the original bit stream.

The method provided in this embodiment of this application may be applied to a communications system that uses probability non-uniform modulation, for example, an intensity modulation-direct detection (Intensity Modulation-Direct Detection, IM-DD for short) communications system with a limited input amplitude, or a radio frequency (Radio Frequency, RF for short) communications system with a limited input signal amplitude, or a radio frequency (Radio Frequency, RF for short) communications system with both a limited input signal amplitude and limited noise power. Typical IM-DD communications systems include a visible light communications (Visible Light Communication, VLC for short) system, a free space optics communication (Free Space Optics, FSO for short) system, a camera communication (Optical Camera Communication, OCC for short) system, an optical wireless scattering communication (Optical Wireless Scattering Communication, OWSC for short) system, and other typical optical wireless communications (Optical Wireless Communication, OWC for short) systems.

An embodiment of this application provides a schematic diagram of a hardware structure of a data transmission apparatus based on probability non-uniform modulation. As shown in <FIG>, the data transmission apparatus <NUM> based on probability non-uniform modulation may be a transmit end or a receive end in the following. Specifically, the data transmission apparatus <NUM> based on probability non-uniform modulation may be a transmit end or a receive end in a radio frequency communication scenario. The data transmission apparatus <NUM> based on probability nonuniform modulation includes at least one processor (for example, a processor <NUM> and a processor <NUM>), a communications bus <NUM>, a memory <NUM>, and at least one communications interface <NUM>.

The processor <NUM> may be one or more general-purpose central processing units (Central Processing Unit, CPU for short), a microprocessor, an application-specific integrated circuit (Application-Specific Integrated Circuit, ASIC for short), or one or more integrated circuits configured to control program execution in the solutions of this application.

The communications bus <NUM> is configured to communicate between the foregoing components, to transmit information.

The communications interface <NUM> is configured to communicate with another device or a communications network, and may be any apparatus such as a transceiver, for example, an Ethernet, a radio access network (Radio Access Network, RAN for short) node, or a wireless local area network (Wireless Local Area Networks, WLAN for short).

The memory <NUM> is configured to store a computer executable instruction for executing the solutions of this application, and the processor <NUM> controls the execution. The processor <NUM> is configured to execute the computer executable instruction stored in the memory <NUM>, to implement a method provided in the following embodiments of this application, for example, to perform an action of a transmit end or a receive end in the following. The memory <NUM> may be a read-only memory (Read-Only Memory, ROM for short) or another type of static storage device that can store static information and an instruction, a random access memory (Random Access Memory, RAM for short) or another type of dynamic storage device that can store information and an instruction, an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM for short), a compact disc read-only memory (Compact Disc Read-Only Memory, CD-ROM for short) or another optical disc storage, an optical disc storage (including a compact disc, a laser disc, an optical disc, a digital versatile disc, a Bluray disc, or the like), a disk storage medium or another magnetic storage device, or any other medium that can be configured to carry or store expected program code in a form of an instruction or a data structure and that can be accessed by a computer, but is not limited thereto. The memory <NUM> may exist independently, and is connected to the processor <NUM> by using the communications bus <NUM>. Alternatively, the memory <NUM> may be integrated with the processor <NUM>.

Optionally, the computer executable instruction in this embodiment of this application may also be referred to as application program code. This is not specifically limited in this embodiment of this application.

In an embodiment, the processor <NUM> may include one or more CPUs, for example, a CPU <NUM> and a CPU <NUM> in <FIG>.

In an embodiment, the data transmission apparatus <NUM> based on probability nonuniform modulation may include a plurality of processors, for example, the processor <NUM> and the processor <NUM> in <FIG>. Each of these processors may be a single-core (single-CPU) processor, or may be a multi-core (multi-CPU) processor. The processors herein may refer to one or more devices, circuits, and/or processing cores configured to process data (for example, a computer program instruction).

In an embodiment, the data transmission apparatus <NUM> based on probability nonuniform modulation may further include an output device <NUM> and an input device <NUM>. The output device <NUM> communicates with the processor <NUM>, and may display information in a plurality of manners. The input device <NUM> communicates with the processor <NUM>, and may receive a user input in a plurality of manners.

An embodiment of this application further provides a data transmission apparatus <NUM> based on probability non-uniform modulation. The data transmission apparatus <NUM> based on probability non-uniform modulation may be the transmit end in the embodiments of this application. The data transmission apparatus <NUM> based on probability non-uniform modulation may be a transmit end in a radio frequency communication scenario, or may be a transmit end in an optical wireless communications scenario.

When the data transmission apparatus <NUM> based on probability non-uniform modulation is a transmit end in a radio frequency communication scenario, as shown in <FIG>, the data transmission apparatus <NUM> based on probability non-uniform modulation may include one or more processors <NUM>, one or more memories <NUM>, one or more baseband processing modules <NUM>, and one or more radio frequency transceivers <NUM>. The radio frequency transceiver <NUM> is configured to receive or send a radio frequency signal. The processor <NUM> is configured to control, according to a program instruction stored in the memory <NUM>, the baseband processing module <NUM> and the radio frequency transceiver <NUM> to perform an action performed by the transmit end in any one of the following method embodiments.

When the data transmission apparatus <NUM> based on probability non-uniform modulation is a transmit end in an optical wireless communications scenario, as shown in <FIG>, the data transmission apparatus <NUM> based on probability non-uniform modulation may include one or more processors <NUM>, one or more memories <NUM>, one or more baseband processing modules <NUM>, one or more light source drivers <NUM>, and one or more light sources <NUM>.

The memory <NUM> is configured to store a program instruction.

The processor <NUM> is configured to control, according to the program instruction stored in the memory <NUM>, the baseband processing module <NUM>, the light source driver <NUM>, and the light source <NUM> to perform an action performed by the transmit end in any one of the following method embodiments.

The baseband processing module <NUM> is configured to generate a physical layer data frame, and send the physical layer data frame to the light source driver <NUM>. The physical layer data frame may be a physical layer data frame mentioned below in this application.

The light source driver <NUM> is configured to generate a direct current or a direct current voltage, superpose the received physical layer data frame with the direct current or the direct current voltage to generate an electrical signal with a bias, and send the electrical signal with a bias to the light source <NUM>.

The light source <NUM> is configured to generate an optical signal based on the electrical signal with a bias.

In some embodiments, the data transmission apparatus <NUM> based on probability nonuniform modulation may further include one or more radio frequency transceivers <NUM>, configured to receive or send a radio frequency signal.

It should be noted that the processor <NUM>, the memory <NUM>, the baseband processing module <NUM>, the light source driver <NUM>, and the radio frequency transceiver <NUM> may be connected by using a bus. The baseband processing module <NUM> may perform channel estimation, and add a channel estimation sequence to the physical layer data frame, or may add a synchronization preamble to the physical layer data frame, or may add processing such as a light adjustment mode to the physical layer data frame.

In some embodiments, the data transmission apparatus <NUM> based on probability nonuniform modulation may further include one or more photoelectric detectors <NUM> and one or more optical antennas <NUM>. For functions of the photoelectric detector <NUM> and the optical antenna <NUM>, refer to related descriptions in the following embodiments related to a receive end.

Based on the transmit end, the channel encoder and the mapper shown in <FIG>, or the equal-probability channel encoder and the non-equal-length Huffman mapper shown in <FIG>, or the multi-level coder and the deterministic equal-length mapper shown in <FIG>, or the single-level coder and the deterministic equal-length mapper shown in <FIG> may be located in the baseband processing module <NUM> at the transmit end.

An embodiment of this application further provides a data transmission apparatus based on probability non-uniform modulation. The data transmission apparatus <NUM> based on probability non-uniform modulation may be the receive end in the embodiments of this application. The data transmission apparatus <NUM> based on probability non-uniform modulation may be a receive end in a radio frequency communication scenario, or may be a receive end in an optical wireless communications scenario.

When the data transmission apparatus <NUM> based on probability non-uniform modulation is a receive end in a radio frequency communication scenario, as shown in <FIG>, the data transmission apparatus <NUM> based on probability non-uniform modulation includes one or more processors <NUM>, one or more memories <NUM>, one or more baseband processing modules <NUM>, and one or more radio frequency transceivers <NUM>. The radio frequency transceiver <NUM> is configured to receive or send a radio frequency signal. The processor <NUM> is configured to control, according to a program instruction stored in the memory <NUM>, the baseband processing module <NUM> and the radio frequency transceiver <NUM> to perform an action performed by the receive end in any one of the following method embodiments.

When the data transmission apparatus <NUM> based on probability non-uniform modulation is a receive end in an optical wireless communications scenario, as shown in <FIG>, the data transmission apparatus <NUM> based on probability non-uniform modulation includes one or more processors <NUM>, one or more memories <NUM>, one or more baseband processing modules <NUM>, one or more photoelectric detectors <NUM>, and one or more optical antennas <NUM>.

The processor <NUM> is configured to control, according to the program instruction stored in the memory <NUM>, the baseband processing module <NUM>, the photoelectric detector <NUM>, and the optical antenna <NUM> to perform an action performed by the receive end in any one of the following method embodiments.

The optical antenna <NUM> is configured to receive an optical signal, and send the optical signal to the photoelectric detector <NUM>.

The photoelectric detector <NUM> is configured to receive the optical signal, convert the optical signal into an electrical signal with a bias, and send the electrical signal with a bias to the baseband processing module <NUM>. The electrical signal with a bias may be a current signal with a bias or a voltage signal with a bias.

The baseband processing module <NUM> is configured to receive the electrical signal with a bias, perform signal processing on the electrical signal with a bias to obtain a physical layer data frame, and perform probability non-uniform demodulation processing and decoding processing on data based on a probability non-uniform demodulation parameter. The probability non-uniform demodulation parameter is a demodulation parameter indicated by indication information in the physical layer data frame. The data is data that is carried in the physical layer data frame and on which probability non-uniform modulation is performed. The physical layer data frame may be a physical layer data frame mentioned below in this application.

It should be noted that the processor <NUM>, the memory <NUM>, the baseband processing module <NUM>, the photoelectric detector <NUM>, and the radio frequency transceiver <NUM> may be connected by using a bus. The baseband processing module <NUM> may perform channel estimation, and add a channel estimation sequence to the physical layer data frame, or may add a synchronization preamble to the physical layer data frame, or may add processing such as a light adjustment mode to the physical layer data frame.

In some embodiments, the data transmission apparatus <NUM> based on probability nonuniform modulation may further include one or more light source drivers <NUM> and one or more light sources <NUM>. For functions of the light source driver <NUM> and the light source <NUM>, refer to related descriptions in the foregoing embodiments related to the transmit end.

Based on the receive end, the demodulator and the decoder shown in <FIG>, or the demodulator and the channel decoder shown in <FIG>, or the multi-level decoder shown in <FIG>, or the joint demapping decoder shown in <FIG> may be located in the baseband processing module <NUM> at the receive end.

An embodiment of this application provides a data transmission method based on probability non-uniform modulation.

A transmit end generates a physical layer data frame, where the physical layer data frame includes data on which probability non-uniform modulation is performed and indication information, and the indication information is used to indicate demodulation parameters for performing probability non-uniform demodulation on the data.

The physical layer data frame may be used for optical wireless communications.

The demodulation parameters include a modulation scheme for probability nonuniform modulation and a modulation order for probability non-uniform modulation. The demodulation parameters further include at least one of the following: a probability of each constellation symbol on which probability non-uniform modulation is performed, and a mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream. It should be noted that all constellation symbols in the embodiment shown in <FIG> are probability non-uniform constellation symbols.

In some embodiments, the indication information is located in a physical layer header of the physical layer data frame. In some embodiments, check protection is performed on the indication information is by using a physical layer header check sequence (Header Check Sequence, HCS for short).

A mapping relationship between a constellation symbol and a bit stream includes information about a bit stream corresponding to the constellation symbol. A constellation symbol may be obtained by modulating a corresponding bit stream. One constellation symbol may correspond to one or more bit streams. For example, <FIG> shows four mapping relationships between constellation symbols and bit streams.

In some embodiments, the demodulation parameters further include a quantity of bits corresponding to each constellation symbol on which probability non-uniform modulation is performed.

In some embodiments, a channel coding scheme may be further included. For example, the channel coding scheme may be multi-level coding or single-level coding.

The transmit end sends the physical layer data frame to the receive end.

The receive end receives the physical layer data frame, and determines the demodulation parameters based on the indication information.

The receive end performs probability non-uniform demodulation on the data based on the demodulation parameters.

In the method provided in this embodiment of this application, the transmit end sends the data on which probability non-uniform modulation is performed to the receive end, and the receive end performs probability non-uniform demodulation on the data, so that a communications system can obtain a better shaping gain, and when there is an input amplitude constraint or on a channel with shot noise, a transmission rate is made closer to a channel capacity or better bit error rate performance is obtained. In the method provided in this embodiment of this application, compared with probability uniform modulation, probability non-uniform modulation generates a non-equal-probability constellation symbol, so that source information entropy and input/output mutual information are larger, and a channel capacity achieved by the probability non-uniform constellation symbol is larger. Therefore, higher frequency band utilization can be obtained in a case of a same input amplitude constraint, same signal power, a same signal-to-noise ratio, and same bit error rate performance, thereby improving transmission efficiency of data on which probability non-uniform modulation is performed.

Different from a conventional probability uniform modulation scheme, probability non-uniform modulation can support a more flexible modulation order, which may not necessarily be <NUM>n (n≥<NUM> and n is an integer). In other words, the modulation order for probability non-uniform modulation may be an odd number. Even in a same modulation scheme, a quantity of bits corresponding to each constellation symbol, a probability of each constellation symbol, and a mapping relationship between a constellation symbol and a bit stream may be greatly different. <FIG> is used as an example. When a modulation order is <NUM>, a quantity of bits corresponding to a constellation symbol in each of case <NUM> and case <NUM> is <NUM>, and a quantity of bits corresponding to a constellation symbol in each of case <NUM> and case <NUM> is <NUM>. Further, mapping relationships between constellation symbols and bit streams may be different even when modulation orders are the same and quantities of bits corresponding to all constellation symbols are the same. Different mapping relationships further cause different probabilities of all the constellation symbols, for example, case <NUM> and case <NUM> in <FIG>. In order to successfully complete probability non-uniform demodulation of a constellation symbol, a demodulator at the receive end needs to completely know information such as a modulation order for probability non-uniform modulation, a quantity of bits corresponding to each constellation symbol, a probability of a constellation symbol, and a mapping relationship between a constellation symbol and a bit stream. Therefore, in this embodiment of this application, the transmit end generates the physical layer data frame based on the demodulation parameters required by the receive end, and sends the physical layer data frame to the receive end, so that the receive end can directly or indirectly extract the demodulation parameters from the received physical layer data frame, and complete probability non-uniform demodulation of the constellation symbol based on the demodulation parameters.

In some embodiments, before step <NUM>, the transmit end generates the data by using a multi-level coder and a deterministic equal-length mapper. In this case, in a specific implementation, step <NUM> may include: performing, by the receive end, probability non-uniform demodulation on the data by using a multi-level decoder and the demodulation parameters. For details, refer to the foregoing manner <NUM>.

In some embodiments, before step <NUM>, the transmit end generates the data by using a single-level coder and a deterministic equal-length mapper. In this case, in a specific implementation, step <NUM> may include: performing, by the receive end, probability non-uniform demodulation on the data by using a joint demapping decoder and the demodulation parameters. For details, refer to the foregoing manner <NUM>.

It should be noted that, in this embodiment of this application, when the data carried in the physical layer data frame is sent by using a single carrier, the data may be data obtained after single-carrier modulation is performed on a probability non-uniform constellation symbol. When the data is sent by using a plurality of carriers, the data may be data obtained after multi-carrier modulation is performed on a probability non-uniform constellation symbol.

The indication information may explicitly or implicitly indicate the demodulation parameters.

When the indication information explicitly indicates the demodulation parameters, the indication information may be the demodulation parameters. In this case, the receive end may directly obtain the demodulation parameters based on the physical layer data frame.

When the indication information implicitly indicates the demodulation parameters, the indication information may be either of the following two types of information:.

In this case, in a specific implementation, step <NUM> may include: determining, by the receive end based on the first identifier and a correspondence between identifiers and demodulation parameters, the demodulation parameters for performing probability non-uniform demodulation on the data, where the identifiers include the first identifier.

For example, as shown in <FIG>, the physical layer data frame generated by the transmit end includes three parts: a physical layer preamble (PHY preamble), a physical layer header (PHY header), and a physical layer data payload (PHY payload).

The physical layer preamble may be used to perform frame synchronization with the receive end, and the preamble is a time domain sequence and does not require any channel coding or signal modulation.

The physical layer header includes a first identifier (which may be referred to as a probability modulation and coding scheme indicator (Probability Modulation and Coding Scheme Index, PMCS-ID for short)), a physical service data unit (PHY service data unit, PSDU for short) length (length), a reserved field (Reserved Fields), and a physical layer HCS.

The PMCS-ID is used to indicate the demodulation parameters. It should be noted that a modulation and coding scheme indicator (Modulation and Coding Scheme Index, MCS-ID for short) in the IEEE <NUM> standard protocol can indicate only a modulation scheme and a modulation order. Different from the MCS-ID, the PMCS-ID in this embodiment of this application not only can indicate a modulation scheme, but also can indicate a modulation order, a probability of each constellation symbol, a mapping relationship between each constellation symbol and a bit stream, a channel coding scheme, and the like in a same modulation scheme.

The PSDU length is used to identify a length of a PSDU in the physical layer data frame. The reserved field is used to support subsequent function expansion. The HCS is used to check the physical layer header.

The data payload includes an optional field (Optional Fields), a channel estimation sequence (Channel Estimation Sequence, CES for short), and a PSDU. The optional area is used for subsequent function expansion. The CES is used for channel estimation and channel equalization. The PSDU is valid data, and in this embodiment of this application, the PSDU may be data on which probability non-uniform modulation is performed.

Specifically, the PMCS-ID may include a plurality of bits used to indicate each piece of information in the demodulation parameters. The receive end may determine, based on a value of a bit in the PMCS-ID and a preset table of a correspondence between different bit values and information in the demodulation parameters, the demodulation parameters indicated by the PMCS-ID.

For example, the PMCS-ID may include m6 bits. a<NUM> to am1 bits are used to indicate a modulation scheme for probability non-uniform modulation. For a correspondence between values of the a<NUM> to am1 bits and the modulation scheme for probability non-uniform modulation, refer to Table <NUM>. am1 to am2 bits are used to indicate a modulation order for probability non-uniform modulation. For a correspondence between values of the am1 to am2 bits and the modulation order for probability non-uniform modulation, refer to Table <NUM>. am2 to am3 bits are used to indicate a quantity of bits corresponding to each constellation symbol. For a correspondence between values of the am2 to am3 bits and the quantity of bits corresponding to the constellation symbol, refer to Table <NUM>. am3 to am4 bits are used to indicate a probability of each constellation symbol. For a correspondence between values of the am3 to am4 bits and the probability of the constellation symbol, refer to Table <NUM>. am4 to am5 bits are used to indicate a mapping relationship between a constellation symbol and a bit stream. For the mapping relationship between a constellation symbol and a bit stream and indicated by values of the am4 to am5 bits, refer to Table <NUM>. am5 to am6 bits are used to indicate a channel coding scheme. For a correspondence between values of the am5 to am6 bits and the channel coding scheme, refer to Table <NUM>. The PMCS-ID may further include another bit, used for subsequent function expansion.

In this case, after receiving the physical layer data frame, the receive end first performs data frame synchronization, and starts to perform channel estimation and channel equalization after completing the data frame synchronization. After the channel estimation and the channel equalization are completed, the demodulator performs probability non-uniform demodulation on the data. The method specifically includes: obtaining a PMCS-ID in a physical layer header, obtaining, based on the PMCS-ID and a preset table (for example, the foregoing Table <NUM> to Table <NUM>) of a correspondence between different bit values and information in demodulation parameters, demodulation parameters indicated by the PMCS-ID, and performing probability non-uniform demodulation on the data based on the demodulation parameters. After probability non-uniform demodulation is performed on the data, a decoder may decode the data by using a message passing/propagation (Message Passing, MP for short) algorithm that can use soft information. For example, the MP algorithm may be a sum-product algorithm.

Further, the demodulator at the receive end may obtain the demodulation parameters indicated by the PMCS-ID after checking that the PMCS-ID is correct by using the check sequence. After the demodulator at the receive end fails to check the PMCS-ID or fails to demodulate or decode the data, the receive end and the transmit end may use a processing method such as data retransmission. For details, refer to the prior art.

In this implementation, the transmit end needs to add only the PMCS-ID to the physical layer data frame to enable the receive end to obtain the demodulation parameters, without needing to add all the demodulation parameters to the physical layer data frame, so that the demodulation parameters for probability non-uniform demodulation are carried with a relatively small information redundancy, thereby improving transmission efficiency, and saving transmission resources.

(<NUM>) The indication information includes a second identifier and a first information portion of the demodulation parameters, the second identifier is used to indicate a second information portion of the demodulation parameters, and the demodulation parameters include the first information portion and the second information portion.

In this case, in a specific implementation, step <NUM> may include: obtaining, by the receive end, the first information portion of the demodulation parameters based on the physical layer data frame; and determining, by the receive end based on the second identifier and a correspondence between identifiers and demodulation parameters, the second information portion of the demodulation parameters for performing probability non-uniform demodulation on the data, where the identifiers include the second identifier.

In some embodiments, the first information portion includes information A and information B, where the information A is a probability of each constellation symbol on which probability non-uniform modulation is performed, the information B is a mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream, and the information A and the information B are located in different fields in a physical layer header of the physical layer data frame.

It should be noted that, in probability non-uniform modulation, there may be a plurality of probabilities of each constellation symbol on which probability non-uniform modulation is performed and a plurality of mapping relationships between each constellation symbol on which probability non-uniform modulation is performed and a bit stream. If the receive end determines a probability or a mapping relationship by looking up the foregoing tables, the receive end needs to consume a large amount of time. In this case, the two pieces of information may be directly carried in the physical layer data frame, thereby reducing demodulation complexity of the receive end.

Certainly, in a specific implementation, other information in the demodulation parameters may be directly carried in the physical layer data frame based on a requirement. This is not limited in this embodiment of this application.

In this case, for the physical layer data frame generated by the transmit end, refer to <FIG>. Compared with <FIG>, in <FIG>, a modulation order and probability (Modulation Order and Probability, MOP for short) module and a bit stream mapping (Bit-stream and Symbol Mapping, BSM for short) module are added to the physical layer header. The module may also be understood as a field.

The second identifier may also be referred to as a PMCS-ID. In this case, the PMCS-ID needs to indicate only some information in the demodulation parameters.

In an implementation, the PMCS-ID may indicate a modulation scheme for probability non-uniform modulation, information about a bit quantity corresponding to each constellation symbol on which probability non-uniform modulation is performed, and a modulation order for probability non-uniform modulation in the demodulation parameters.

The probability of each constellation symbol on which probability non-uniform modulation is performed may be included in the MOP module (or referred to as a MOP field, and the field may alternatively have another name). The mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream may be included in the BSM module (or referred to as a BSM field, and the field may alternatively have another name).

In this case, after receiving the physical layer data frame, the receive end first performs data frame synchronization, and starts to perform channel estimation and channel equalization after completing the data frame synchronization. After the channel estimation and the channel equalization are completed, the demodulator performs probability non-uniform demodulation on the data. The method specifically includes: obtaining a PMCS-ID in a physical layer header; obtaining, based on the PMCS-ID and a preset table (for example, the foregoing Table <NUM>, Table <NUM>, and Table <NUM>) of a correspondence between different bit values and information in the demodulation parameters, a modulation scheme for probability non-uniform modulation, bit quantity information corresponding to each constellation symbol on which probability non-uniform modulation is performed, and a modulation order for probability non-uniform modulation in the demodulation parameters that are indicated by the PMCS-ID; obtaining, from the MOP module and the BSM module, a probability of each constellation symbol on which probability non-uniform modulation is performed and a mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream in the demodulation parameters; and performing probability non-uniform demodulation on the data based on the obtained demodulation parameters. After performing probability non-uniform demodulation on the data, the decoder may perform data decoding by using an MP algorithm (for example, a sum-product algorithm) that can use soft information.

In another implementation, the PMCS-ID may indicate a modulation scheme for probability non-uniform modulation and bit quantity information corresponding to each constellation symbol on which probability non-uniform modulation is performed in the demodulation parameters.

The modulation order for probability non-uniform modulation and the probability of each constellation symbol on which probability non-uniform modulation is performed in the demodulation parameters may be included in the MOP module (or referred to as an MOP field, and the field may alternatively have another name). The mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and the bitstream may be included in the BSM module (or referred to as a BSM field, and the field may alternatively have another name).

In this case, after receiving the physical layer data frame, the receive end first performs data frame synchronization, and starts to perform channel estimation and channel equalization after completing the data frame synchronization. After the channel estimation and the channel equalization are completed, the demodulator performs probability non-uniform demodulation on the data. The method specifically includes: obtaining a PMCS-ID in a physical layer header; obtaining, based on the PMCS-ID and a preset table (for example, the foregoing Table <NUM> and Table <NUM>) of a correspondence between different bit values and information in the demodulation parameters, a modulation scheme for probability non-uniform modulation and bit quantity information corresponding to each constellation symbol in the demodulation parameters that are indicated by the PMCS-ID; obtaining, from the MOP module and the BSM module, a modulation order for probability non-uniform modulation, a probability of each constellation symbol on which probability non-uniform modulation is performed, and a mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream in the demodulation parameters; and performing probability non-uniform demodulation on the data based on the obtained demodulation parameters. After performing probability non-uniform demodulation on the data, the decoder may perform data decoding by using an MP algorithm (for example, a sum-product algorithm) that can use soft information.

Further, the demodulator at the receive end may obtain the demodulation parameters indicated by the PMCS-ID and the demodulation parameters included in the MOP module and the BSM module after checking that the PMCS-ID, the MOP module, and the BSM module are correct by using the check sequence. After the demodulator at the receive end fails to check the PMCS-ID, the MOP module, or the BSM module, or fails to demodulate and decode the data, the receive end and the transmit end may use a processing method such as data retransmission. For details, refer to the prior art.

In this implementation, the transmit end adds the PMCS-ID to the physical layer data frame, and adds some of the demodulation parameters to the physical layer data frame, so that the receive end can directly obtain the some of the demodulation parameters, thereby reducing a demodulation delay and demodulation complexity of the demodulator.

Compared with probability uniform modulation, probability non-uniform modulation implemented in the method provided in some embodiments of this application generates a non-equal-probability constellation symbol, so that source information entropy and input/output mutual information are larger, and a channel capacity achieved by the probability non-uniform constellation symbol is larger. Therefore, higher frequency band utilization can be obtained in a case of a same input amplitude constraint, same signal power, a same signal-to-noise ratio, and same bit error rate performance. In some embodiments of this application, the added MOP and BSM modules can directly carry information in the demodulation parameters, thereby supporting a constellation symbol probability that is more flexible and has higher quantization accuracy. The probability non-uniform constellation symbol in some embodiments of this application may be extended to N-dimensional signal space (N≥<NUM> and N is a positive integer).

The foregoing mainly describes the solutions of the embodiments of this application from a perspective of a method. It may be understood that, to implement the foregoing functions, the data transmission apparatus based on probability non-uniform modulation includes corresponding hardware structures and/or software modules for performing the functions. A person skilled in the art should easily be aware that, in combination with units and algorithm steps of the examples described in the embodiments disclosed in this specification, this application may be implemented by hardware or a combination of hardware and computer software. Whether a function is performed by hardware or hardware driven by computer software depends on particular applications and design constraints of the technical solutions.

In the embodiments of this application, functional units of the data transmission apparatus based on probability non-uniform modulation may be divided based on the foregoing method examples. For example, each functional unit may be obtained through division based on each corresponding function, or two or more functions may be integrated into one processing unit. It should be noted that, in this embodiment of this application, unit division is exemplary, and is merely a logical function division. In actual implementation, another division manner may be used.

For example, when an integrated function module is used, <FIG> is a possible schematic structural diagram of an apparatus in the foregoing embodiments. The apparatus <NUM> may be the foregoing transmit end or receive end. Referring to <FIG>, the apparatus <NUM> may include a processing unit <NUM> and a communications unit <NUM>. The apparatus may further include a storage unit <NUM>.

When the apparatus <NUM> is the transmit end, the processing unit <NUM> is configured to control and manage an action of the transmit end. For example, the processing unit <NUM> is configured to support the transmit end in performing steps <NUM> and <NUM> in <FIG> and/or an action performed by the transmit end in another process described in the embodiments of this application. The communications unit <NUM> is configured to support the transmit end in communicating with another network device, for example, communicating with the receive end in <FIG>. The storage unit <NUM> is configured to store program code and data of the transmit end.

When the apparatus <NUM> is the receive end, the processing unit <NUM> is configured to control and manage an action of the receive end. For example, the processing unit <NUM> is configured to support the receive end in performing steps <NUM> and <NUM> in <FIG> and/or an action performed by the receive end in another process described in the embodiments of this application. The communications unit <NUM> is configured to support the receive end in communicating with another network device, for example, communicating with the transmit end in <FIG>. The storage unit <NUM> is configured to store program code and data of the receive end.

In one case, the processing unit <NUM> may be a processor or a controller, the communications unit <NUM> may be a communications interface, and the storage unit <NUM> may be a memory. When the processing unit <NUM> is a processor, the communications unit <NUM> is a communications interface, and the storage unit <NUM> is a memory, the apparatus in this embodiment of this application may be the apparatus shown in <FIG>.

When the apparatus shown in <FIG> is the transmit end, the processor <NUM> is configured to control and manage an action of the transmit end. For example, the processor <NUM> is configured to support the transmit end in performing steps <NUM> and <NUM> in <FIG> and/or an action performed by the transmit end in another process described in the embodiments of this application. The communications interface <NUM> is configured to support the transmit end in communicating with another network device, for example, communicating with the receive end in <FIG>. The memory <NUM> is configured to store program code and data of the transmit end.

When the apparatus shown in <FIG> is the receive end, the processor <NUM> is configured to control and manage an action of the receive end. For example, the processor <NUM> is configured to support the receive end in performing steps <NUM> and <NUM> in <FIG> and/or an action performed by the receive end in another process described in the embodiments of this application. The communications interface <NUM> is configured to support the receive end in communicating with another network device, for example, communicating with the transmit end in <FIG>. The memory <NUM> is configured to store program code and data of the receive end.

In another case, the apparatus in this embodiment of this application may be the apparatus shown in <FIG>.

When the apparatus shown in <FIG> is the transmit end, the processing unit <NUM> may be the baseband processing module <NUM>, the communications unit <NUM> may include the light source driver <NUM> and the light source <NUM>, and the storage unit <NUM> may be the memory <NUM>. The baseband processing module <NUM>, the light source driver <NUM>, and the light source <NUM> perform, under control of the processor <NUM> based on the program instruction stored in the memory <NUM>, the action of the transmit end in the foregoing method. For functions of the baseband processing module <NUM>, the light source driver <NUM>, and the light source <NUM>, refer to the foregoing descriptions.

When the apparatus shown in <FIG> is the receive end, the processing unit <NUM> may be the baseband processing module <NUM>, the communications unit <NUM> may include the photoelectric detector <NUM> and the optical antenna <NUM>, and the storage unit <NUM> may be the memory <NUM>. The baseband processing module <NUM>, the photoelectric detector <NUM>, and the optical antenna <NUM> perform, under control of the processor <NUM> based on the program instruction stored in the memory <NUM>, the action of the receive end in the foregoing method. For functions of the baseband processing module <NUM>, the photoelectric detector <NUM>, and the optical antenna <NUM>, refer to the foregoing descriptions. An embodiment of this application further provides a computer-readable storage medium, including an instruction. When the instruction is run on a computer, the computer is enabled to perform the foregoing method.

An embodiment of this application further provides a computer program product including an instruction. When the computer program product is run on a computer, the computer is enabled to perform the foregoing method.

All or some of the foregoing embodiments may be implemented by using software, hardware, firmware, or any combination thereof. When a software program is used to implement the embodiments, the embodiments may be implemented completely or partially in a form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the procedure or functions according to the embodiments of this application are all or partially generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable apparatuses. The computer instructions may be stored in a computer-readable storage medium or may be transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (for example, a coaxial cable, an optical fiber, or a digital subscriber line (Digital Subscriber Line, DSL for short)) or wireless (for example, infrared, radio, or microwave) manner. The computer storage medium may be any usable medium accessible by a computer, or a data storage device, such as a server or a data center, integrating one or more usable media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, a DVD), a semiconductor medium (for example, a solid-state drive (Solid State Disk, SSD for short)), or the like.

Claim 1:
A data transmission method based on probability non-uniform modulation, comprising:
generating (<NUM>), by a transmit end, a physical layer data frame, wherein the physical layer data frame comprises data on which probability non-uniform modulation is performed and indication information, the indication information is used to indicate demodulation parameters for performing probability non-uniform demodulation on the data, the demodulation parameters comprise a modulation scheme for probability non-uniform modulation and a modulation order for probability non-uniform modulation, and the demodulation parameters further comprise at least one of the following: a probability of each constellation symbol on which probability non-uniform modulation is performed, and a mapping relationship between each constellation symbol on which probability non-uniform modulation is performed and a bit stream; and
sending (<NUM>), by the transmit end, the physical layer data frame to a receive end.