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CN109104250B - Star 24QAM mapping-based optical probability forming coding method - Google Patents

Star 24QAM mapping-based optical probability forming coding method Download PDF

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CN109104250B
CN109104250B CN201811183836.4A CN201811183836A CN109104250B CN 109104250 B CN109104250 B CN 109104250B CN 201811183836 A CN201811183836 A CN 201811183836A CN 109104250 B CN109104250 B CN 109104250B
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CN109104250A (en
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刘博�
张丽佳
毛雅亚
韩顺
忻向军
孙婷婷
赵立龙
吴泳锋
刘少鹏
宋真真
王俊锋
哈特
姜蕾
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Nanjing University of Information Science and Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/54—Intensity modulation
    • H04B10/541—Digital intensity or amplitude modulation
    • H—ELECTRICITY
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    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H04L27/3411—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power reducing the peak to average power ratio or the mean power of the constellation; Arrangements for increasing the shape gain of a signal set

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Abstract

本发明公开了一种基于星型24QAM映射的光概率成型编码方法，信号输入后首先进行串并变换，通过概率匹配器，把输入的信号映射为星型32QAM信号，通过概率匹配的方式把星型32QAM信号映射成为星型24QAM，成形信号输出并进行星座映射。本发明增加了系统的信道容量和传输性能。

Figure 201811183836

The invention discloses an optical probability shaping coding method based on star-shaped 24QAM mapping. After the signal is input, serial-to-parallel conversion is performed first, the input signal is mapped into star-shaped 32QAM signal through a probability matcher, and the star-shaped 32QAM signal is mapped by probability matching method. Type 32QAM signal is mapped into star type 24QAM, shaped signal output and constellation mapping. The present invention increases the channel capacity and transmission performance of the system.

Figure 201811183836

Description

Star 24QAM mapping-based optical probability forming coding method
Technical Field
The invention relates to an optical probability forming coding method, in particular to an optical probability forming coding method based on star 24QAM mapping.
Background
An access network refers to all devices between a user terminal and a backbone network, ranging from hundreds of meters to kilometers in length, and is therefore often referred to as the "last kilometer". When a user uploads or downloads data, signals need to pass through a backbone network and an access network, and because a transmission medium in the backbone network is generally an optical fiber, the transmission speed is high, and the transmission capacity is large, the access network becomes a short board for data transmission, so the intuitive experience of each user is directly influenced by the quality of the signal transmission speed and the signal quality of the access network. With the development of society, the spiritual life and the entertainment mode of people are continuously enriched, the bandwidth of 2M can meet the requirements of people in the past few years, the current HDTV (high Definition television), blue-ray video, high-speed downloading and network games become the daily requirements of households, the hundred megabroadband even can not meet the network requirements of three families, and the requirement for accessing the network is higher.
In order to increase the processing speed and transmission rate of signals as much as possible, in recent years, a breakthrough has been made in the direction of increasing the transmission carrying capacity of a single-channel carrier to approach the shannon limit, and probability shaping has been widely paid attention as an effective method for increasing the channel capacity and reducing the information error rate. Through the combination of probability shaping and Low Density Parity Check (LDPC) coding, Amplitude Phase Shift Keying (APSK) signal shaping, QAM and constellation shaping, the method is found to effectively improve various aspects of performance of signal processing.
QAM is a modulation in which the amplitude and phase of a carrier signal are used to represent different bits of information. This modulation format combines multilevel level amplitude with orthogonal carrier techniques to further improve band utilization. Due to its excellent characteristics, it has been widely used in the fields of satellite communication, high-speed data transmission of digital television, etc. However, QAM signals are still limited by the minimum euclidean distance, and cannot concentrate a large number of constellation points at the origin of the constellation diagram, which results in the reduction of the system channel capacity, so probability shaping provides a solution.
The current probability shaping mainly aims at mapping conventional constellations, such as 8PSK, 16QAM, 32QAM constellations, and the like. The space utilization rate of the conventional constellation diagram is low, and the system performance is limited due to overlarge space gap under the same Euclidean distance, the transmission power redundancy is increased, and the transmission rate and the channel capacity are reduced.
Disclosure of Invention
The invention aims to solve the technical problem of providing an optical probability forming coding method based on star 24QAM mapping, and increasing the channel capacity and the transmission performance of a system.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
an optical probability forming coding method based on star 24QAM mapping is characterized by comprising the following steps:
the method comprises the following steps: after the signal is input, firstly carrying out serial-parallel conversion;
step two: mapping an input signal into a star 32QAM signal through a probability matcher, and mapping the star 32QAM signal into a star 24QAM through a probability matching mode;
step three: the shaped signal is output and constellation mapped.
Further, in the second step, the star 32QAM signal needs five bytes to represent information, the first two bytes represent the number of turns of the constellation point, and the last three bytes represent the phase information of the constellation point.
Further, the process of mapping the star 32QAM signal into the star 24QAM signal in the second step is as follows
A. Dividing the constellation points of the outermost circle into three parts, and mapping the three parts into the inner three circles of the same phase;
b, dividing the constellation points of the third circle into three parts, and mapping the three parts into inner three circles which comprise the same phase of the original constellation points;
C. the constellation point of the second circle is divided into two parts, the two parts are mapped into the constellation point of the innermost circle with the same phase point and the original position, and meanwhile, the constellation point of the innermost circle is unchanged.
Further, in the second step, the first step,
due to Eavg＝∑ipi×Ei，
Wherein the i subscript denotes the corresponding constellation point, EiRepresents a correspondingEnergy values of the constellation points;
then, the average energy value of the star 32QAM constellation with uniform distribution can be obtained
Figure BDA0001825686010000031
The average energy value of the formed novel star 24-point constellation diagram is
Figure BDA0001825686010000032
PAPR＝max(Ei)/Eavg，
Where PAPR represents the peak-to-average power ratio, max (E)i) Represents the maximum power point of the constellation diagram; then there are
Figure BDA0001825686010000033
Figure BDA0001825686010000034
Compared with the prior art, the invention has the following advantages and effects: the invention provides star 24QAM modulation based on probability forming, a constellation diagram of original data is firstly mapped into star 32QAM, and then is mapped into star 24QAM again through a probability matcher, and the mode is under the condition of meeting the minimum Euclidean distance, the space advantage of the constellation diagram is enriched, and meanwhile, the nonlinear tolerance of a transmission channel is improved, so that the channel capacity and the transmission performance of a system are increased.
Drawings
FIG. 1 is a flow chart of the optical probability modeling coding method based on star 24QAM mapping of the present invention.
Fig. 2 is a constellation diagram of original 32QAM of an embodiment of the present invention.
Fig. 3 is a constellation diagram of star 32QAM in accordance with an embodiment of the present invention.
Fig. 4 is a schematic diagram of converting a star 32QAM constellation to a 24QAM constellation according to an embodiment of the present invention.
Fig. 5 is a constellation diagram of star 24QAM in accordance with an embodiment of the present invention.
FIG. 6 is a probability distribution diagram of star 24QAM according to an embodiment of the present invention.
Fig. 7 is a receiving end constellation diagram according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail below by way of examples, which are illustrative of the present invention and are not limited to the following examples, in conjunction with the accompanying drawings.
As shown in fig. 1, the optical probability shaping coding method based on star 24QAM mapping of the present invention,
after signals are input, series-parallel conversion is firstly carried out, then a probability matcher is used, the probability matcher is mainly divided into two parts, the first part is used for mapping the input signals into star 32QAM signals, and the second part is used for mapping the star 32QAM signals into star 24QAM signals in a probability matching mode.
The conventional 32QAM constellation is square and the mapping is as shown in figure 2. The probability matcher is firstly mapped into a star 32QAM constellation diagram, the star 32QAM mapping mode is shown in FIG. 3, the star 32QAM requires five bytes to represent information, the first two bytes represent the number of turns of the constellation point, and the last three bytes represent the phase information of the constellation point.
The original star 32QAM is converted into 24QAM by the probability matcher in the way of FIG. 4. Dividing the constellation points of the outermost circle into three parts, and mapping the three parts into the inner three circles of the same phase; dividing the constellation points of the third circle into three parts, and mapping the three parts into inner three circles which comprise the same phase of the original constellation points; the constellation point of the second circle is divided into two parts, the two parts are mapped into the constellation point of the innermost circle with the same phase point and the original position, and meanwhile, the constellation point of the innermost circle is unchanged. The constellation after mapping is shown in fig. 5.
Due to Eavg＝∑ipi×Ei，
Wherein the i subscript denotes the corresponding constellation point, EiRepresenting the energy value of the corresponding constellation point.
Then, the average energy value of the star 32QAM constellation with uniform distribution can be obtained
Figure BDA0001825686010000051
The average energy value of the formed novel star 24-point constellation diagram is
Figure BDA0001825686010000052
From this, we can clearly see that the average power of the signal is greatly reduced after probability shaping and constellation improvement.
PAPR＝max(Ei)/Eavg，
Where PAPR represents the peak-to-average power ratio, max (E)i) Representing the maximum power point of the constellation. Then there are
Figure BDA0001825686010000053
Figure BDA0001825686010000054
It can be seen that the peak-to-average power ratio is obviously improved after probability shaping and constellation improvement. This shows that the energy concentration of the signal is greatly improved after probability shaping and constellation diagram improvement, and basically meets the requirement of shaping on reducing the signal transmission power. The reduction of the average energy of the signal means that the energy value of the signal after constellation shaping is far greater than the energy value of the signal without the constellation shaping under the condition of the same signal transmission power, so that the signal-to-noise ratio of the signal is improved from a relative angle, and the channel capacity value is improved.
Due to the probability matcher, when the signal is mapped to the star 24QAM, the probability distribution of the signal changes, and as can be seen from fig. 6, the probability of the inner circle of the constellation is obviously higher than that of the outer circle.
And inputting the single-path binary bit stream to a serial-parallel conversion unit, and outputting five paths of parallel binary stream signals after serial-parallel conversion. And identifying and labeling the generated five-path binary data, and confirming a final output signal through a label set to which the identification signal belongs. After passing through the probability forming matcher, the distribution of the constellation points in the output signal achieves the purposes of improving the distribution probability of low-energy constellation points and reducing the distribution probability of high-energy constellation points. In QAM constellation mapping, a star 24QAM mapping mode is combined, under the condition that the requirement of the minimum Euclidean distance is met, the total transmitting power of signals is further reduced by shrinking redundant space, and the performance maximization of signal forming is realized. To this end, probability shaping and coded modulation of the star 24QAM constellation are completed.
At the receiving end, an amplifier is used to adjust the signal power to facilitate reception. The demodulator is used for converting the optical signal into an electric signal, the QAM modulator demodulates the 24QAM signal, and then the distributor de-distributor of the distribution matcher removes redundancy of the centralized signal to obtain an original input signal.
The constellation diagram of the receiving end is obtained through simulation and experimental tests, as shown in fig. 7, the constellation diagram is received after passing through an additive white gaussian noise channel, and the probability distribution of the constellation points conforms to the star probability distribution provided by the invention.
The above description of the present invention is intended to be illustrative. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.

Claims (3)

1.一种基于星型24QAM映射的光概率成型编码方法，其特征在于包含以下步骤：1. a light probability shaping coding method based on star 24QAM mapping, is characterized in that comprising the following steps: 步骤一：信号输入后首先进行串并变换；Step 1: After the signal is input, serial-to-parallel conversion is performed first; 步骤二：通过概率匹配器，把输入的信号映射为星型32QAM信号，通过概率匹配的方式把星型32QAM信号映射成为星型24QAM；Step 2: Map the input signal into a star-shaped 32QAM signal through a probability matcher, and map the star-shaped 32QAM signal into a star-shaped 24QAM signal by means of probability matching; 所述步骤二中把星型32QAM信号映射成为星型24QAM过程为The process of mapping the star-shaped 32QAM signal to the star-shaped 24QAM signal in the second step is: A、把最外圈的星座点分为三份，映射入相同相位的内三圈中；A. Divide the constellation points of the outermost circle into three parts and map them into the inner three circles of the same phase; B把第三圈的星座点也分为三份，映射入包括自己原来星座点的相同相位的内三圈中；B also divides the constellation points of the third circle into three parts, and maps them into the inner three circles including the same phase of their original constellation points; C、把第二圈的星座点分为两份，映射入最内圈相同相位点和原先所在星座点，同时最内圈星座点不变；C. Divide the constellation points of the second circle into two parts, and map them into the same phase point of the innermost circle and the original constellation point, while the constellation point of the innermost circle remains unchanged; 步骤三：成形信号输出并进行星座映射。Step 3: Shape the signal output and perform constellation mapping. 2.按照权利要求1所述的基于星型24QAM映射的光概率成型编码方法，其特征在于：所述步骤二中星型32QAM信号需要五个字节来表示信息，前两个字节代表了该星座点所在的圈数，后三个字节代表了星座点的相位信息。2. according to the optical probability shaping coding method based on star-shaped 24QAM mapping according to claim 1, it is characterized in that: in described step 2, star-shaped 32QAM signal needs five bytes to represent information, and the first two bytes represent the information. The number of circles where the constellation point is located, and the last three bytes represent the phase information of the constellation point. 3.按照权利要求1所述的基于星型24QAM映射的光概率成型编码方法，其特征在于：所述步骤二中，3. according to the optical probability shaping coding method based on star 24QAM mapping according to claim 1, it is characterized in that: in described step 2, 由于because
Figure FDA0002850150740000011
Figure FDA0002850150740000011
 其中i下标表示对应的星座点，Ei表示相应星座点的能量值；The i subscript represents the corresponding constellation point, and E i represents the energy value of the corresponding constellation point; 那么，由此可得均匀分布的星型32QAM星座图的平均能量值为Then, the average energy value of the uniformly distributed star-shaped 32QAM constellation is obtained as
Figure FDA0002850150740000021
Figure FDA0002850150740000021
 经过成形后的新型星型24点星座图的平均能量值为The average energy value of the new star-shaped 24-point constellation diagram after shaping is
Figure FDA0002850150740000022
Figure FDA0002850150740000022
 PAPR＝max(Ei)/Eavg,PAPR=max(E i )/E avg , 其中PAPR表示峰均功率比，max(Ei)表示星座图的最大功率点；那么有where PAPR represents the peak-to-average power ratio, and max(E i ) represents the maximum power point of the constellation; then there are
Figure FDA0002850150740000023
Figure FDA0002850150740000023
Figure FDA0002850150740000024
Figure FDA0002850150740000024
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CN111030961B (en) * 2019-12-18 2022-04-05 南京信息工程大学 Signal modulation and demodulation method based on constellation structure optimization and cell-like area decision
CN111049586B (en) * 2019-12-25 2020-11-03 南京信息工程大学 A Pulse Amplitude Position Modulation System Based on Down-amplitude Probabilistic Shaping
CN113067665B (en) 2020-01-02 2022-03-11 海思光电子有限公司 Encoding method, decoding method and device
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