754 results about "Constellation diagram" patented technology

Systematic transmit IQ phase and amplitude imbalances in the transmit chain of a wireless local area network (WLAN) cause a corresponding systematic shift in the roots of a constellation diagram. Additional random phase noise in the transmit chain will cause a further Gaussian distribution of points in the constellation diagram about the systematically shifted roots. This random distribution represents a true error vector magnitude (EVM). By transmitting a known training sequence through the transmit chain, which it is known will be shifted to all of the systematically shifted roots in the constellation diagram, the Gaussian spread around those shifted roots can be analysed to determine the true EVM.

A unequal protection hybrid automatic retransfer request method based on equality and un-equality constellation diagram mapping, it is used in MQAM communication system with which the stage numbers is M and M=2, the modulation mapping of sending end and the resolving mapping of receiving end adopt constellation diagrams that have same distribution, in the first transmission and anterior m / 2-1 time retransmission, adopts equality constellation diagram, at the m / 2 time and the latter retransmission adopts un-equality constellation diagram, provides higher error protection for two most significant bit in the modification symbol; the bits un-equality protection in the modification symbol of sending end reset; uses m / 2 reset and opposite reset rules, at different retransmission time adopts circularly in turn, achieves alternative protecting the bits in modulation symbol; the bits in modulation symbol of receiving end reset oppositely. Reset oppositely the bits according to the reset rules of sending end, recover it into bits sequence soft value before sending end bits resetting. It promotes the signals S / N of combining soft value after demodulating and resolving mapping at receiving end, reduces efficiently grouping retransmission time, makes the output of system maximum.

Disclosed is a non-equal probability constellation labeling method based on an absolute phase shift keying (APSK) constellation diagram. The non-equal probability constellation labeling method based on the APSK constellation diagram is characterized by comprising the steps that: the APSK constellation diagram is constructed, number of steps of the constellation labeling is M, M=2m, and m is a positive integer, numbers of constellation points on each ring is the same, phase deviations of each ring are also the same; a constellation labeling mode of the APSK constellation diagram is designed, and the constellation labeling mode is enabled to be a gray labeling; the constellation points are grouped, and constellation points on the same ring are combined to be a new constellation point; labeling bits of the prior constellation points on the same ring are distributed to the new constellation point in sequence. According to the non-equal probability constellation labeling method based on the APSK constellation diagram, the inhomogeneous constellation diagram and a non-equal probability labeling technology are adopted, distribution of output signals of the constellation labeling is enabled to be close to Gaussian distribution, shaping gain is achieved, performance of a coded modulation system is improved, and signal to noise ratio in a modulation process is reduced.

The invention discloses a deep learning intelligent constellation diagram analysis method based on a convolutional neural network, and relates to the technical field of optical communication. According to the method, the performance analysis on a constellation diagram is performed by building and training a convolutional neural network module. The method comprises the following steps of acquiring a training data set of a constellation diagram; preprocessing the constellation diagram; training a CNN module for feature extraction; inputting the to-be-analyzed and preprocessed constellation diagram into the well trained CNN module for pattern recognition and performance analysis; and outputting an analysis result. According to the invention, the depth learning technology based on the convolutional neural network is applied to the constellation diagram analysis. In this way, the problem in the prior art that, the problem that original data cannot be directly processed and needs to be manually intervened during the traditional constellation diagram performance analysis can be solved. By using the CNN module, the intelligence and the automation of analysis of the original image information of the constellation diagram are achieved. As a result, the module can be used as a constellation diagram software processing and analyzing module of an oscilloscope and a constellation diagram analyzing module of the simulation software to be further embedded into a test instrument for intelligent signal analysis and performance monitoring.

The invention discloses an information transmission method for reducing the peak to average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. In the method, after being coded and interleaved, data stream is modulated by a new distorted constellation diagram so as to acquire a frequency domain signal; for the frequency domain signal, a phase rotation sequence is selected to reduce the PAPR of a time domain signal which is subjected to inverse fast Fourier transform (IFFT); at a receiver end, the received signal is subjected to fast Fourier transform (FFT) and channel estimation so as to acquire the frequency domain signal; for the frequency domain signal, recovering is performed by different phase rotation sequences so as to acquire candidate signals; amongthe candidate signals, only the signal which is recovered by the right phase rotation sequence has a minimal mean square error when the signals are subjected to hard decision together with the constellation diagram; and the candidate signal which has the minimal mean square error is selected as the original signal, and the corresponding phase rotation sequence is the recovered side band information. The method can effectively reduce the peak to average power ratio of the OFDM signal, does not need to send the side band information simultaneously, improves the frequency band utilization ratio of systems, and can be applied to various communication systems using OFDM technology.

An anti-phase noise amplitude phase combined keying modulation and demodulation method belongs to the technical field of modulation and demodulation, the method is characterized in that, a circular constellation diagram construction method and a circular constellation diagram selection method are firstly utilized for designing a constellation diagram structure with good symbol error performance; secondly, a bit mapping algorithm which is proposed by the invention is utilized for solving the difficulty of carrying out the Gray-code mapping of other constellation diagrams except the quadrature amplitude modulation (QAM), thereby ensuring the bit error performance of the proposal; the demodulation proposal with high reliability and low complexity is further matched for use, the actual bit error performance is not only far better than the QAM which uses the Gray codes under the phase noise, but also has no obvious loss compared with the Gray-code QAM when in only consideration of Gaussian white noise; finally, the design method which is proposed by the invention is simple and easy to operate, thereby being easily expanding to any order, facilitating the application in a communication system with serious phase noise of global digital broadcasting and the like and possibly reducing the costs and the complexity of a receiver at the same time of ensuring the symbol error performance of the system.

A receiver for receiving data in a broadcast system includes a broadcast receiver that receives, via the broadcast system, a receiver input data stream including plural channel symbols represented by constellation points in a constellation diagram. A demodulator demodulates the channel symbols into codewords and a decoder decodes the codewords into output data words. A broadband receiver obtains redundancy data via a broadband system, the redundancy data for a channel symbol including one or more least robust bits of the channel symbol or a constellation subset identifier indicating a subset of constellation points including the constellation point representing the channel symbol. The demodulator and / or the decoder is configured to use the redundancy data to demodulate the respective channel symbol and to decode the respective codeword, respectively.

The invention provides a combined modulation recognition method based on clustering and a support vector machine in order to overcome the shortcoming of low modulation recognition rate of a clustering algorithm with a low signal to noise ratio. According to the method, a characteristic parameter of a modulation signal is extracted by using the clustering algorithm according to a phase shift keying / quadrature amplitude modulation (PSK / QAM) mode based on a constellation diagram; and a modulation mode for a signal is recognized through the support vector machine, so that the modulation recognition rate of a system is increased. The method comprises the following steps of: aiming at the PSK / QAM mode based on the constellation diagram, reconstructing the constellation diagram of a receiving signal by using the clustering algorithm; and obtaining an effective function value, which can reflect an outstanding difference of modulation types under different clustering central numbers, as the characteristic parameter input into the support vector machine by constructing an effectiveness evaluation function. In order to overcome the shortcoming that two common algorithms of one to multiple and one to one have high calculation complexity when the support vector machine recognizes multiple types, the support vector machine is trained by adopting a hierarchical algorithm.

Methods and apparatuses providing a visual metric of the efficiency of a network of devices communicating through a wireless access point (AP). These apparatuses and methods may also determine and display pseudo-dynamic error vector magnitude (EVM) information for a network of wireless stations, including displaying a pseudo-dynamic constellation diagrams using EVM information. These methods and apparatuses may transmit a plurality of sounding packets from each of one or more radio devices different modulation types (e.g., BPSK, QPSK, 16QAM, 64QAM, 256QAM and 1024QAM), and receiving at least some of the sounding packets at a second radio device (e.g., an access point) and determining EVM information from the received sounding packets, and displaying (or providing for display) a constellation diagram including pseudo-dynamic EVM information that is a constrained approximation of actual EVM information.

A receiver for receiving data in a broadcast system includes a broadcast receiver that receives via the broadcast system a receiver input data stream including plural channel symbols represented by constellation points in a constellation diagram, a demodulator that demodulates the channel symbols into codewords, and a decoder that decodes the codewords into output data words. A redundancy calculator determines a required amount of redundancy data required for correct demodulation and decoding by use of the originally received channel symbol and additional redundancy data. A broadband request unit requests, if demodulation of a channel symbol and / or decoding of a codeword is erroneous or likely to fail, a required amount of redundancy data via a broadband system, that is received by a broadband receiver via said broadband system. The demodulator and / or the decoder is configured to use the redundancy data for demodulation and decoding, respectively.

The invention relates to a constellation diagram limited extended code modulation method, a demodulation and decoding method and a system thereof. The extended code modulation method comprises the following steps: conducting channel coding and bit interleaving to input information bits to obtain coded and interleaved bits; conducting constellation mapping to the coded and interleaved bits by using an M-point K-dimensional constellation diagram to obtain constellation diagram limited K-dimensional extended constellation mapping symbols, wherein M and K are positive integers larger than one; and conducting coordinate interleaving to the K-dimensional extended constellation mapping symbols to obtain extended code modulation symbol output of an N-point constellation diagram in a backward compatible original system, wherein N is a positive integer no less than M. By adopting the novel code modulation method, on the premise that the modulation constellation diagram of the original system isnot changed, the invention has the advantages that the application scope of the original system is expanded and improved, the spectrum utilization is reasonable and the system resources are saved.

The invention discloses a rotation constellation diagram based coding and decoding method for a spatial multiplex multi-aerial system. According to the method, the rotation constellation diagram based coding and decoding method and the spatial multiplex multi-aerial system are combined, a transmission signal is subjected to serial and parallel conversion at a transmitting end and a mapped onto a modulation constellation diagram, all constellation points rotate by using origin points as circle centers at set angles and reversely rotate at the same set angles after signs are detected at a receiving end, a signal sequence is modulated through the constellation diagram and is subjected to parallel and serial conversion, and the signal is output. By the method, the problem of error rate increase caused by constellation point overlap in a related channel is solved, and the error rate of the spatial multiplex multi-aerial system in the related channel is reduced better on the premise of not increasing system bandwidth resources and unnecessarily reducing transmission rate. Compared with the traditional spatial multiplex multi-aerial system, only a rotation factor is multiplied at the transmitting end and the receiving end, and the coding method is low in hardware cost and excellent in error code performance.

The invention discloses a group dividing method and a device based on network user behavior. The method comprises the following steps: determining a behavior characteristic parameter set according to user requirement; constructing a user type space according to the determined behavior characteristic parameter set; reading data from a user behavior server, normalizing various parameters of each user, forming a user constellation diagram in the user type space, initializing each point in the constellation diagram, and determining a searching range; calculating a moving distance vector according to the distance from points in the searching range of the point to the point, and updating the searching range according to the moving distance vector; repeating the performed steps until all points are fixed; and forming a user group by adjacent points according to the initial searching range.

The invention discloses an MIMO radar communication integration method based on antenna array arrangement modulation, and belongs to the technical field of radar and communication. The method comprises the steps that firstly, a reference dictionary is constructed and a constellation diagram is designed according to an MIMO radar system; phase rotation is performed on the transmitting waveform at atransmitting terminal, and the constellation diagram is updated; then a binary communication data flow to be transmitted is divided into a plurality of code elements, and an array element-waveform paring mode corresponding to each code element is found out; finally, a radar transmitting terminal adjusts the transmitting array structure through changing the state of a radio frequency switch and transmits the corresponding radar pulse waveform; a radar receiving terminal processes the radar echo and realizes target detection; a communication receiving terminal processes a radar pulse signal andobtains an estimated value of an ordered steering vector of the radar transmitting array; constellation points in the constellation diagram are traversed to find out a constellation point which is the closest to the estimated value of the ordered steering vector, and binary information is demodulated. The MIMO radar communication integration method realizes downlink transmission of communication,significantly improves the data transmission rate, reduces the communication error rate and enhances the system reliability.

The invention relates to OFDM (Orthogonal Frequency Division Multiplexing) system signal sending method, receiving method and device. The methods comprise the steps of: carrying out serial / parallel conversion on an input signal for constellation modulation; encrypting the signal subjected to the constellation modulation, wherein the encrypting operation includes the steps of: implementing paseudorandom constellation diagram rotation on the signal subjected to the constellation modulation, and adding weak artificial noise in the signal subjected to paseudorandom constellation diagram conversion, wherein each constellation point rotates a random angle which is appointed by a system sending end and a legal receiving end; and emitting after carrying OFDM modulation. The methods and the device can obtain higher safety and confidentiality by using the randomness of the constellation diagram rotating angle and the inconvertibility of the weak artificial noise, and can ensure the compatibility with the traditional communication system.

The invention discloses an MIMO signal detection method and a device that are applied in a system with two receiving antennas. The method includes the following steps: storing the respective size relationship between all constellation points corresponding to modulation modes adopted by the system and the Euclidean distance of positions on a constellation diagram in advance; conducting sequencing QR decomposition on channel matrix and demodulating a first layer of signal points from a receiving signal according to elements at the lower right corner of R matrix; according to the size relationship of the Euclidean distance corresponding to the modulation mode adopted by the first layer of signal points, finding out the first layer of K constellation points with the minimum Euclidean distancefrom the position of the first layer of signal points on the constellation diagram; and searching a second layer of constellation points based on every found constellation point of the first layer, selecting a search path with the minimum Euclidean distance from all search paths where the first layer of constellation points is located and determining the signal detection result according to the first layer of constellation points and the second layer of constellation points on selected K search paths. The application of the method and the device can ensure signal detection performance and simultaneously reduce the complexity of MIMO signal detection.

The invention discloses a method for retransmitting a hybrid automatic request. Four constellation diagrams are defined in the method to form a rearranging HARQ technology based on a 256-QAM constellation diagram. The method comprises the following steps that: a) the first constellation diagram is defined as a standard constellation diagram, and the rearrangement of significance bit for other constellation diagrams based on the first constellation diagram is performed; b) data is mapped to the first constellation diagram to modulate and transmit, after a binary random bit stream generated by an information source is scrambled and coded by a transmitting terminal; c) a receiving terminal passes through an inverse process of step b), decodes and judges the data after modulation, when the data is correct, the data is descrambled and transmitted to an information sink; when the data is incorrect, NACK is transmitted to the transmitting terminal, and the data is mapped to the second constellation diagram, and so on, the data is mapped to the third constellation diagram and the fourth constellation diagram for the modulation and transmission in the third time and the fourth time; when the transmitting terminal receives the NACK for the fourth time, the data is mapped to the first constellation diagram once more for the modulation and the transmission, thereby finishing the circulation.

The invention provides a method for reducing a peak average power ratio (PAPR) under APSK (Amplitude Phase Shift Keying) constellation diagram mapping in OFDM (Orthogonal Frequency Division Multiplexing) modulation. According to the method provided by the invention, as the amplitude of signals is limited on a time domain, when time domain signals are converted onto frequency domain constellation points, only the constellation points at an outer layer of the APSK are expanded, only the frequency domain constellation points expanding outwards are remained, and a process of time domain amplitude limitation-frequency domain selection expansion is iterated for a plurality of times. Therefore, the rate of occurring peak signals can be reduced, and the PAPR of the OFDM signals can be reduced. According to the algorithm, an expansion area and an expansion rule are designed under the APSK constellation diagram mapping, so that the error code property cannot be worsened under the APSK modulation. The method provided by the invention can be applied to an OFDM system under the APSK constellation diagram mapping, so that the effect of reducing the PAPR can be achieved well.

The invention provides a remote underwater acoustic communication method based on soft-demodulation soft-decoding joint iteration. The method comprises the following steps that: a transmitting end performs low density parity check (LDPC) coding on a binary information sequence which is sent by a signal source, performs quaternary phase shift keying (QPSK) modulation and Gray mapping, maps code elements to one of four positions in a constellation diagram by taking two code elements as a group, performs Walsh-m composite sequence spectrum spreading to obtain a signal to be transmitted, and converts a digital signal to be transmitted into an underwater acoustic signal; and an underwater acoustic transducer at a receiving end converts the received underwater acoustic signal, de-spreads by using a composite sequence which is the same as that of the transmitting end to obtain a receiving signal, performs self-adaptation decision feedback equalization to obtain an amplitude fading complex signal, performs soft-demodulation soft-decoding joint iteration on the signal, stops joint iteration after set iteration frequency is reached, performs belief propagation (BP) decoding on an LDPC decoder and outputs a bit value to a sink. By the method provided by the invention, the reliability of remote underwater acoustic communication is improved. The method is applicable to the remote underwater acoustic communication.

The invention discloses a carrier frequency deviation estimation and compensation method of a single-carrier frequency domain balance system in great-frequency deviation condition. The method comprises the following steps of: performing related operation of the received frame header repetitive sequence to obtain a rough frequency deviation estimated value, and performing open-loop compensation processing on the signal by use of the frequency deviation estimated value; after frequency deviation compensation, processing the signal through balance and the like to obtain a demodulated constellation diagram; calculating the rotary phase of the constellation diagram to obtain a fine frequency deviation estimated value; and feeding the estimated value back to a balancer part, and performing closed-loop compensation to finish the estimation and compensation of the signal frequency deviation. The method disclosed by the invention has the characteristics of large range of estimated frequency deviation, high precision of frequency deviation compensation, moderate algorithm complexity and the like, and is particularly suitable for the single-carrier frequency domain balance communication system in great-frequency deviation environment.

The invention relates to a low-precision large-scale antenna system based on probabilistic shaping and a coding modulation method thereof. In the low-precision large-scale antenna system, a sending end performs probabilistic shaping coding, channel coding and constellation mapping on information bits, and a receiving end performs low-precision quantization processing, probabilistic shaping detection, channel decoding and reverse probabilistic shaping on received signals, so that the information bits are detected. The coding modulation design method comprises the following steps: analyzing theinfluence of low-precision quantization on transmission constellation diagram energy distribution of the low-precision large-scale antenna system; based on an analysis result and the channel type of the receiving end, optimizing the sending probability distribution of the sending end, and obtaining an optimal transmission sending probability; and realizing coding modulation design based on the optimal transmission sending probability. Compared with the prior art, the low-precision large-scale antenna system based on the probabilistic shaping and the coding modulation method thereof provided bythe invention have the advantages of reducing the capacity loss caused by the quantification and the like.

The apparatus includes a radio frequency (RF) unit configured to arrange a plurality of symbols received through an antenna at a frequency domain, an analog to digital (AD) converter configured to converts the plurality of symbols arranged at the frequency domain to digital symbols, a fast Fourier transform (FFT) unit configured to transform the digital symbols through a fast Fourier transform scheme, a compensator configured to compensate a gain mismatch between an I-channel and a Q-channel of the transformed digital symbols, a mapping unit configured to the compensated digital symbols to a constellation diagram, and a detector configured to correlate the mapped symbols, extract correlation results, and detect a high throughput (HT) signal using the extracted correlation results.

Provided is a method for transforming data using a look-up table. The method includes the steps of: (a) mapping preprocessed input binary data to a constellation diagram divided into four quadrants to output a first complex number; (b) performing addition / subtraction operations between real numbers and between imaginary numbers with respect to the first complex number and a second complex number; and (c) reading a fourth complex from a look-up table in response to the first complex number, the second complex number and a third complex number, the look-up table outputting the fourth complex by performing a subtraction operation on multiplication results between real numbers and between imaginary numbers and an addition operation on multiplication results between the real numbers and the imaginary numbers with respect to the result value of the step (b) and the third complex number. Accordingly, it is possible to reduce the hardware size at the time of IFFT / FFT design and to provide a high-speed, low-power operation.

The invention discloses a method for eliminating pulse noise based on compressed sensing, which is characterized in that in allusion to serious interference imposed on data transmission by pulse noise in a PLC system, the pulse noise is projected to non-data subcarriers according to a CS (Compressed Sensing) algorithm utilizing all OFDM subcarrier information to estimate and eliminate the pulse noise, a compressed sensing problem is built firstly by using pulse noise l1-norm minimization according to an l1-norm minimization based compressed sensing technology, a judgment condition on OFDM symbol non-data subcarriers is introduced to act as a constraint condition, the range of a rectangle in a constellation diagram is modulated through introducing QAM (Quadrature Amplitude Modulation), convex relaxation is performed on the constraint condition, the original problem is simplified into a linear programming problem, the linear programming problem is solved by using the existing method, and a simulation result is displayed in channel coded and channel uncoded 4-QAM and 16-QAM modes. The method disclosed by the invention has better bit error rate performance than several conventional methods.

The invention relates to an SCMA codebook design method based on the maximization sum distance of constellation points. The method comprises the following steps of: firstly, maximizing the sum distance among projection points of a rotated QPSK constellation on a coordinate axis, selecting an optimal rotation angle represented by a formula as shown in the specification, and taking the QPSK constellation having the rotation angle represented by a formula as shown in the specification as a mother constellation C+ after normalization processing; then, respectively rotating the projection of the mother constellation C+ on an X axis in alpha, beta and gamma, and constructing a constellation diagram that three users are stacked on a single resource block; on the premise that alpha is kept constant, maximizing a sum distance function f(alpha, beta, gamma) among the constellation points of the three users stacked on the single resource block so as to obtain optimized rotation angles beta and gamma; and finally, designing an operation factor matrix delta<j> according to alpha and the corresponding optimized angles beta and gamma, and furthermore, in combination with a mapping matrix V<j>, mapping the two-dimensional mother constellation C+ to obtain codebooks U<j> of six users, wherein j is 1, 2, ..., 6. According to the method disclosed by the invention, the sum distance among four constellation points of each user and the sum distance among the constellation points of three users stacked on each resource block are respectively maximized through optimal calculation for two times; and thus, the bit error rate performance of the system is improved.

The invention discloses an encoding modulating method. In a modulating process, regular constellation mapping or irregular constellation mapping is carried out on bit data, so as to obtain a constellation mapping symbol, wherein the regular constellation mapping means that the mapping from a bit to a symbol is completed by adopting one constellation diagram and one constellation point mapping way, and the irregular constellation mapping means that the mapping from the bit to the symbol is completed by adopting one constellation diagram and more than one constellation point mapping ways. The invention further discloses a demodulation decoding method corresponding to the encoding demodulating method. In the invention, through using regular APSK (amplitude phase shift keying) constellation mapping at a sending end, the shaping loss can be obviously reduced, or by using irregular QAM (quadrature amplitude modulation) constellation mapping, the decoding and the de-mapping are matched more,so as to improve the transmission capability of an encoding modulating system, and through adopting iterative de-mapping at a receiving end, the loss brought by independent de-mapping can be effectively reduced, so as to obviously improve the performance of the encoding modulating system based on the iterative de-mapping.

A wireless device receives a frequency division multiplexed (FDM) symbol of constituent equalized FDM data subcarriers. A modulation scheme constellation diagram is subdivided into two or more regions. For each of the regions, a subset of the subcarriers that fall within the region are extracted and a respective region-specific CPE estimate is computed thereon. The respective region-specific CPE estimates are averaged to produce an overall CPE estimate used to compensate the subcarriers. Furthermore, a first CPE estimate is computed using pilot symbols embedded in a first received FDM symbol and is used to compensate the subcarriers. A following second FDM symbol that has no embedded pilot symbols is compensated using the first CPE estimate, and a second CPE estimate is computed using a blind estimation method on the second FDM symbol compensated subcarriers, which are compensated using the second CPE estimate.

The invention discloses a signal interference detection method and a signal interference detection device. The method comprises the following steps of: traversing a data constellation diagram of frequency domain signals according to the received channel response of sub-carriers in the frequency domain signals in a frequency domain, and determining transmitted signal estimated values corresponding to the sub-carriers; determining interference and noise power estimated values of the sub-carriers according to the transmitted signal estimated values and the channel response; for frequency points of each sub-carrier in the received frequency domain signals, counting the interference and noise power estimated values of the sub-carriers at each frequency point, and computing a mean value of the interference and noise power estimated values of each sub-carrier at each frequency point; and comparing the computed mean value with a preset interference and noise power threshold value to determine whether interference exists at each frequency point or not. By the method and the device, interference signals in a system can be effectively detected with high accuracy and reliability.

An embodiment of the invention provides a method and a device for generating an optical signal based on geometric-probability shaping. The method comprises the following steps: acquiring original datato be sent; determining, according to sequence numbers of each constellation subset, a subset serial number sequence obeying the optimal distribution corresponding to the original data, and determining a binary sequence of the subset serial number sequence obeying the optimal distribution corresponding to the original data according to binary labels of each of the constellation subsets, wherein the constellation subsets are obtained by performing subset division on the multi-mode circular constellation after performing geometric forming on square constellation diagrams of the preset number ofconstellation points to obtain a multi-mode circular constellation; systematically coding the binary sequence to obtain the encoded information; sequentially selecting a first preset number of information bits and a second preset number of redundant bits for the encoded information, and mapping the above bits to the multi-mode circular constellation to obtain an optical signal to be transmitted.This embodiment enables the transmitted light signal to approximate the Shannon channel capacity.

The invention discloses a method for constructing a multimode quadrature amplitude modulation (QAM) uniform constellation diagram label and a modulator. By the method, a uniform label which comprises various 2<2n> QAM square constellation diagrams is constructed, wherein n is a natural number and is more than or equal to 1; a constellation mapping table generated by the uniform label is stored into a designed constellation mapping module of a multimode QAM modulator, so that the modulator can adaptively finish 2<2n> QAM in different modes according to different control signals; only a uniform constellation mapping table is stored in hardware and all constellation mapping tables containing the modes do not need to be stored respectively during multimode 2<2n> QAM; therefore, during the hardware implementation, the utilization rate of hardware resources is increased; furthermore, switching among different modes of 2<2n> QAM is easy and convenient to control.