Adaptive non-orthogonal uplink multiple access method based on energy consumption

Abstract

The present invention relates to the technical field of wireless communications. Disclosed is an adaptive non-orthogonal uplink multiple access method based on energy consumption. In the present invention, a plurality of users are paired on the basis of their distances from a base station; for a user close to the base station and having a small configured transmitting power, a DFT-s-OFDM waveform is used, and for a user far away from the base station and having a large configured transmitting power, the waveform of a signal to be transmitted is adaptively selected on the basis of the device energy level; that is, the DFT-s-OFDM waveform can be selected when the energy consumption level is high, and a low-energy-consumption waveform CE-OFDM is used when the energy consumption level is low. In the present invention, improved serial interference cancellation detection suitable for a new uplink access scheme is further configured at a receiving end; by means of the detection mode, when the waveform of a remote user is unknown to the base station, global detection can be performed by means of pattern recognition to complete data detection of the remote user. By means of blind recognition by a base station, additional signaling or resource overhead related to waveform indication can be effectively avoided.

Description

Energy Consumption-Based Adaptive Non-Orthogonal Uplink Multiple Access Method Technical Field The present invention belongs to the field of wireless communication technologies, and particularly relates to an energy consumption level-based adaptive uplink non-orthogonal multiple access method that uses a hybrid waveform of Discrete Fourier Transform-spread-OFDM (DFT-s-OFDM) and Constant Envelope Orthogonal Frequency Division Multiplexing (CE-OFDM). Background Art NOMA (Non-Orthogonal Multiple Access) transmits multiple user signals superimposed on the same orthogonal time-frequency resource block in different ways to achieve system overload. To meet the requirements of massive connections, PD-NOMA (Power Domain Non-Orthogonal Multiple Access) introduces a new dimension, namely the power domain, to achieve non-orthogonal allocation of resources through power domain multiplexing, thereby improving system capacity. However, in the PD-NOMA system, users use traditional OFDM waveforms, and the signals generated by non-orthogonal superposition have an excessively high Peak to Average Power Ratio (PAPR), which reduces the power utilization rate of power amplifiers and affects the effective coverage range and energy consumption level of uplink multiple access. Summary of the Invention The present invention provides an energy consumption-based adaptive non-orthogonal uplink multiple access method to ensure the access quality of low-energy-consuming devices and increase the system's adaptability to the energy consumption differences of different devices. The technical solution adopted by the present invention is as follows: For an energy consumption-based adaptive non-orthogonal uplink multiple access method in a wireless communication system including CE-OFDM modulation and DFT-s-OFDM modulation, the number of valid symbols of DFT-s-OFDM modulation is N DFT , the number of valid symbols N of CE-OFDM modulation c , the number of subcarriers carrying information at the transmitter is N, the oversampling factor is Q, and the number of subcarriers in the full frequency band N all = NQ. The users at the transmitter are paired in pairs by the system. The two users in each pair of users are divided into a proximal user and a distal user based on the distance between the transmitter where they are located and the receiver. The system configures corresponding power weights for each pair of users. The power weight of the proximal user is denoted as P 1 , and the power weight of the distal user is denoted as P 2, where \(0\leq P\) 2 \(\leq P\) 1 \(\leq1\), and \(P\) 1 \(+P\) 2 \(=1\); The method includes: The transmission waveform of the proximal user adopts the DFT-s-OFDM waveform, and the distal user determines its transmission waveform according to the current energy consumption level of the transmitter: if the energy consumption level is greater than the preset energy consumption threshold of the system, the DFT-s-OFDM waveform is adopted; if the energy consumption level is less than or equal to the energy consumption threshold, the CE-OFDM waveform is adopted; The signal transmission steps when the transmitter adopts the DFT-s-OFDM waveform include: Step a1. Digital modulation: Map the information bits to be transmitted into M-order QAM (Quadrature Amplitude Modulation) modulation to obtain a modulation signal with a symbol length of N DFT Step a2. DFT (Discrete Fourier Transform) precoding and oversampling: Pass the modulation signal through the N DFT -point DFT transform to generate signal X 1 ; Oversample signal X 1 to obtain a frequency-domain signal with a symbol length of N all Step a3. Subcarrier mapping and then IFFT (Inverse Fast Fourier Transform) conversion: Pass the frequency-domain signal through the N all -point IFFT transform to generate a time-domain OFDM (Optical Frequency Division Multiplexing) signal x with a symbol length of N all 1 ; Step a4. Add cyclic prefix (CP): Add a cyclic prefix with a length of N 1 to signal x to obtain the transmission signal s of the current transmitter user CP 1 ; Step a5. Power configuration: If the current transmitter user is a proximal user, then based on the transmission power P allocated by the system t configure the transmission power of the transmission signal s of the proximal user to be 1 ​​​​​If the current transmitting end user is a remote user, then based on the transmit power P allocated by the system t Configure the transmit signal s of the remote user 1 The transmit power of is When the transmitting end adopts the CE-OFDM waveform, the signal transmission steps include: Step b1. Digital modulation: Map the information bits to be transmitted to M-QAM modulation to obtain a modulation signal X with a symbol length of N c ; 2 ; Step b2. Symmetric mapping: Place the modulation signal X according to a predetermined conjugate symmetric format to obtain a frequency-domain signal with a symbol length of N 2 ; all ; Step b3. Frequency-domain to time-domain transformation: Perform an N -point IFFT transformation on the frequency-domain signal to generate a time-domain OFDM symbol x with a symbol length of N all ; all ; 2 ; Step b4. Phase modulation: Obtain a discrete-time domain CE-OFDM signal s' with a symbol length of N by phase-modulating the time-domain OFDM symbol x 2 ; all ; 2 ; Step b5. Add cyclic prefix: Add a cyclic prefix with a length of N to the signal s' to obtain the transmit signal s of the current transmitting end user 2 ; CP ; 2 ; Step a6. Power configuration: Based on the transmit power P allocated by the system t Configure the transmit power of the transmit signal s of the remote user 2 to be The signal reception and processing steps at the receiving end include: Step c1. Time-domain to frequency-domain transformation: Remove the cyclic prefix of the received signal, and after serial-to-parallel conversion, perform an N all -point FFT (Fast Fourier Transform) transformation to obtain the frequency-domain received signal Y; Step c2. Hybrid waveform data processing: Step c2-1. Perform equalization processing on the frequency-domain received signal Y to obtain an equalized symbol with a symbol length of N all and use it as the signal to be detected Y of the proximal user in the current user pair ; 1 ; The signal Y to be detected 1 Perform subcarrier demapping (i.e., extract data at corresponding positions in the frequency domain), and then transform it to the time domain through IDFT (Inverse Discrete Fourier Transform), and perform M-QAM demodulation after serial-to-parallel conversion to obtain the bit data U of the proximal user 1 ; Step c2-2. For the bit data U 1 Perform M-QAM modulation, DFT, oversampling, and IFFT in sequence to obtain the signal s' 1 Then transform it to the frequency domain signal S' through FFT 1 ; Cancel the interference of the proximal user from the frequency domain received signal Y And then divide by the corresponding power factor To obtain the signal to be detected of the distal user Wherein, Represents the channel estimation result from the proximal user to the receiving end, P 1 , P 2 Are respectively the receiving powers of the receiving end for the proximal user and the distal user; For the signal to be detected Perform equalization processing and use it as the signal to be detected Y of the distal user 2 ; Step c2-3. Obtain the first alternative bit data under the first alternative waveform (DFT-s-OFDM waveform) of the distal user: For the signal to be detected Y 2 Perform subcarrier demapping, then transform it to the time domain through IDFT, and perform M-QAM demodulation after serial-to-parallel conversion to obtain the alternative bit data of the distal user Then based on the alternative bit data Remap according to steps a1-a3 to generate a DFT-s-OFDM signal with a symbol length of N all And then transform it to the frequency domain to obtain the frequency domain signal And calculate the Euclidean distance Wherein, Wherein, Indicates the channel estimation result from the remote user to the receiver; Step c2-4. Based on the signal to be detected Y 2 Obtain the second alternative bit data of the remote user under the second alternative waveform (CE-OFDM waveform) The corresponding transmitted symbol vector And calculate the corresponding Euclidean distance Step c2-5. Determine the final bit data U of the remote user based on the Euclidean distance 2 : If Then the transmission waveform of the remote user is the DFT-s-OFDM waveform, and the bit data U of the remote user 2 Is If Then the transmission waveform of the remote user is the CE-OFDM waveform, and the bit data U of the remote user 2 Is Furthermore, in step c2-4, obtain the second alternative bit data of the remote user The corresponding transmitted symbol vector Is any one of the following two methods: Method 1: First, transform Y 2 To the time domain for phase demodulation (i.e., arctangent demodulation) and then perform FFT transformation. After subcarrier demapping processing, perform M-QAM demodulation to obtain the second alternative bit data of the remote user For the alternative bit data Remap and generate a CE-OFDM signal with a symbol length of N according to steps b1-b4 all Of Then transform to the frequency domain to obtain Method 2: Demodulate through the ML (Maximum Likelihood) algorithm. There are Alternative vector spaces. Define Ω to represent all possible transmitted symbol vectors before phase modulation when the remote user adopts the CE-OFDM waveform Of the set, where The vector dimension of is 1×N all, the set Ω contains elements; Then the ML detection algorithm estimates the user's data, that is: Based on Calculate the corresponding Euclidean distance. At this time, if the transmission waveform of the remote user is a CE-OFDM waveform, then The valid data in is converted into the corresponding estimated bit sequence to obtain the detection result of the remote user (i.e., the bit data ). The technical solution provided by the present invention has at least the following beneficial effects: In the present invention, for the user pairs set in the system, the user close to the base station and with a small transmission power configuration uses the DFT-s-OFDM waveform, while the user far from the base station and with a large transmission power configuration adaptively selects the waveform of the transmitted signal according to the device energy level, that is, the DFT-s-OFDM waveform can be selected when the energy consumption level is good, and the low-energy consumption waveform CE-OFDM is used when the energy consumption level is low. The present invention also sets an improved successive interference cancellation (SIC) detection applicable to the new uplink access scheme at the receiving end. This detection method can perform global detection through pattern recognition when the base station does not know the waveform of the remote user, and complete the data detection of the remote user. Through base station blind recognition, the additional signaling or resource overhead related to waveform indication can be effectively avoided. Description of the Drawings In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts. Figure 1 is a block diagram of the signal processing process at the transmitting end where the proximal user is located in the embodiment of the present invention; Figure 2 is a block diagram of the signal processing process at the transmitting end where the remote user is located in the embodiment of the present invention; Figure 3 is a block diagram of the signal receiving and processing process at the receiving end (base station) in the embodiment of the present invention. Detailed Embodiments To make the purpose, technical solutions and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail with reference to the drawings. Regarding the high PAPR problem of PD-NOMA based on traditional OFDM waveforms, low-power consumption waveforms can be used to replace traditional OFDM waveforms. Embodiments of the present invention propose two alternative low-power consumption waveforms: DFT-s-OFDM and CE-OFDM. Among them, the DFT-s-OFDM waveform improves the uplink signal fluctuation range through precoding, and the CE-OFDM waveform modulates the OFDM time-domain symbols onto the phase of a constant envelope carrier signal through phase modulation, improving the power efficiency of the power amplifier to varying degrees and reducing the transmission energy consumption. And CE-OFDM has more ideal PAPR characteristics than DFT-s-OFDM, and thus can obtain better energy consumption performance. As a possible implementation, the energy consumption-based adaptive non-orthogonal uplink multiple access provided by the embodiments of the present invention The method is specifically as follows: In a wireless communication system based on CE-OFDM modulation and DFT-s-OFDM modulation, the transmitting-end users are paired in pairs by the system into several pairs of user pairs. Based on the distance between the transmitting end where the user is located and the receiving end (base station), the users in the user pair are divided into a proximal user (defined as user 1) and a distal user (defined as user 2), that is, the channel of user 1 has a smaller attenuation, and the channel attenuation of user 2 is larger; and the system configures corresponding power weights for each pair of user pairs. The power weight of the proximal user is denoted as P 1 , and the power weight of the distal user is denoted as P 2 , where,, 0 ≤ P 2 ≤ P 1 ≤ 1, and P 1 + P 2 = 1; At the same time, for the transmission waveform used, user 1 defaults to using the DFT-s-OFDM waveform, and user 2 can choose the DFT-s-OFDM or CE-OFDM waveform according to its own energy consumption level; define the energy consumption threshold as α (0 < α ≤ 100%). When the energy consumption is higher than α, user 2 uses the DFT-s-OFDM waveform. When the energy consumption is lower than α, user 2 uses the more energy-efficient CE-OFDM waveform; assume that the energy consumption level of user 2 is lower than α and uses the CE-OFDM waveform; define the number of valid symbols of DFT-s-OFDM modulation as N DFT , the number of valid symbols N of CE-OFDM modulation c , the number of subcarriers carrying information is N, the oversampling factor is Q, and the frequency-domain selective fading channel of the system is h. Based on the number of subcarriers N and the oversampling factor Q, the total frequency band subcarrier number N all = NQ; The method includes the following steps: As shown in Figure 1, the signal transmission step (DFT-s-OFDM process) of the uplink user 1 transmitting end includes: a1. Digital modulation: Map the information bits of User 1 to an M - order QAM modulation to obtain a modulated signal It is expressed as: Where, represents the modulated signal The nth (n = 0, …, N DFT - 1) symbol, and the symbol is represented as a complex vector, represents is a complex vector of dimension 1×N DFT a2. DFT precoding and oversampling: Perform an N - point DFT transform on the modulated signal DFT to generate signal X 1 , which is expressed as: Where, X 1 [k] represents the kth sampling - point symbol of signal X 1 , e represents the natural base, and j represents the imaginary unit. Perform oversampling on signal X 1 to obtain a frequency - domain symbol all of length N a3. Sub - carrier mapping and then IFFT conversion: Perform an N all - point IFFT transform to generate the time - domain OFDM signal of User 1 The time - domain OFDM symbol x 1 at the nth sampling point of User 1 is expressed as: Where, the symbol represents the set of real numbers, represents x 1 is a real vector of dimension 1×N all represents the kth (k = 0, …, N all - 1) sampling - point symbol of the frequency - domain symbol ; ​​a4. Add CP: Add a cyclic prefix to obtain the transmission signal of User 1 It can be expressed as: s 1 =[x 1 [N all -N CP +1],…,x 1 [N all -1],x 1 [0],x 1 [1],…,x 1 [N all -1]] T where N CP is the cyclic prefix length; a5. Power configuration: Based on the transmission power P allocated by the system t configure the transmission power of the transmission signal s of the proximal user 1 to be That is, for the proximal user, the transmission power of each sampled point symbol of its transmission signal s 1 is configured to be s 1 [n] represents the nth (n = 0,…,N 1 +N all -1) sampled point symbol of the transmission signal s, that is, s CP [0] = x 1 [N 1 -N all +1], s CP [N 1 +N all +N CP -1] = x 1 [N all -1]. It should be noted that when the energy consumption level of the distal user (uplink user 2) is higher than the energy consumption α, it uses the DFT-s-OFDM waveform, and the transmission signal s corresponding to user 2 is obtained through the above steps a1~a4 1 , and during power configuration, based on the transmission power P allocated by the system t configure the transmission power of this transmission signal s 1 to be As shown in Figure 2, the signal transmission steps (CE-OFDM process) at the transmitter of uplink user 2 include: b1. Digital modulation: Map the information bits of user 2 to obtain a modulated signal after M-QAM modulation It can be expressed as: X 2 = [X 2 (0), X 2 (2), …, X 2 (N c - 1)] T Among them, X 2 (n) represents the nth (n = 0, …, N 2 - 1) symbol of X c ; b2. Adaptive waveform selection according to the energy consumption threshold: Obtain the user's current energy consumption level (that is, obtain its energy consumption measurement value, which can be obtained by any method, and the embodiments of the present invention do not make specific limitations). If the current energy consumption level is higher than the threshold α, generate a DFT-s-OFDM waveform according to steps a2 - a5, and then jump to step b7 for power configuration; if the current energy consumption level is equal to or lower than the threshold α, generate a CE-OFDM waveform according to steps b3 - b6, and then complete the power configuration according to b7. b3. Symmetric mapping: Place X 2 in the following conjugate symmetric format to obtain a frequency-domain symbol with a length of N all ; That is Among them, N zp = N(Q - 1), (·) * represents conjugation, and 0 1×N represents a zero vector with one row and N columns; b4. Frequency-domain to time-domain transformation: Transform through an N all -point IFFT transformation to generate the time-domain OFDM symbol of user 2 The time-domain OFDM symbol x 2 [n] at the nth sampling point of user 2 is expressed as: Among them, represents the kth (k = 0, …, N all - 1) sampling point symbol of b5. Phase modulation: Modulate the time-domain OFDM symbol x 2 of user 2 through phase modulation to obtain a discrete time-domain CE-OFDM signal The nth (n = 0, …, N all-1) The discrete-time domain CE-OFDM symbol s′ at the sampling point 2 is expressed as: φ 2 = 2πhC N x 2 [n] where A is the amplitude of the carrier signal and 2πh is the modulation index; is the normalization constant factor. b6. Add CP: Add a cyclic prefix to obtain the transmitted signal of User 2 s 2 = [s′ 2 [N all -N CP +1], …, s′ 2 [N all -1], s′ 2 [0], s′ 2 [1], …, s′ 2 [N all -1]] T b7. Power configuration: Based on the transmitted power P allocated by the system t configure the transmitted power of the transmitted signal s of the remote user 2 to be That is, the transmitted power of each sampling point symbol (s 2 [n], n = 0, …, N 2 +N all -1) of the transmitted signal s is configured to be CP As shown in Figure 3, the signal reception processing at the base station receiver includes: c1. Time domain-frequency domain transformation: Remove the CP from the received signal and perform an N all point FFT transformation to obtain the frequency domain received signal is expressed as: where H 1 and H 2 respectively represent the transmission channels from User 1 and User 2 to the base station, S 1 and S 2 respectively represent the received signals of the base station for User 1 and User 2, W represents the channel noise, and P r represents the received power configured by the system, are respectively the received powers of the base station for User 1 and User 2. Due to the distance relationship between the users and the base station, the power magnitudes satisfy: c2. Hybrid waveform data processing procedure: c2-1: Among the signal powers received by the base station, the received power of the proximal user is greater, and the interference to the other user is relatively greater. Therefore, the user signals are detected in the order from the user closest to the base station to the farthest. The serial interference cancellation method is used to detect the superimposed signal at the receiving end. First, Y is equalized to obtain the equalized symbol This is used as the signal Y to be detected for User 1 1 , assuming that the waveform used by User 1 is DFT-s-OFDM as set. The base station first extracts the data at the corresponding positions in the frequency domain, then transforms it to the time domain through IFFT, and finally performs M-order QAM demodulation to obtain the bit data of the first user. c2-2: To detect the data of the second user, first perform M-order QAM modulation, DFT, oversampling, and IFFT on the bit data of User 1 obtained in step c2-1 to obtain s′ 1 , and then perform FFT to convert it into a frequency-domain signal S′ 1 . After canceling the interference of User 1 from the received signal and then dividing by the corresponding power factor, the signal to be detected for User 2 is obtained It is expressed as follows: c2-3: When the base station does not know whether the waveform selected by User 2 is DFT-s-OFDM or CE-OFDM, first assume it is the DFT-s-OFDM waveform of the user, represents the channel estimation result from User 2 to the base station. Take and obtain the equalized symbol through equalization, which is used as the signal Y to be detected for User 2 2 , the base station extracts the data at the corresponding positions in the frequency domain, then transforms it to the time domain through IFFT, and finally performs M-order QAM demodulation to obtain the first alternative bit data of the user Then, based on the alternative bit data remap and generate a DFT-s-OFDM signal according to steps a1-a3 Then transform it to the frequency domain to obtain Finally, calculate the Euclidean distance c2-4: Assume it is the user CE-OFDM waveform. The following two options are both CE-OFDM demodulation methods. If the base station has weak processing capabilities and low performance requirements, perform step d1. If the base station has strong processing capabilities and high performance requirements, perform step d2. Option 1: First, transform Y 2 to the time domain for phase demodulation (i.e., arctangent demodulation), then perform an FFT transformation, extract the data at the corresponding positions, and perform M-QAM demodulation to obtain the second alternative bit data of user 2. Then, based on the alternative bit data re-map according to steps b1-b5 to generate a CE-OFDM signal. Then transform back to the frequency domain to obtain Finally, calculate the Euclidean distance Compare and If then the detection result of user 2 is If then the detection result of user 2 is Option 2: Demodulate through the ML algorithm. There are alternative vector spaces. Ω represents the set of all possible transmitted symbol vectors before phase modulation when user 2 at the transmitting end uses CE-OFDM. The set Ω contains elements. Then, estimate the user's data through the ML detection algorithm, that is, Keep the Euclidean distance Compare and If then the detection result of user 2 is If then finally convert the valid data in to the corresponding estimated bit sequence to obtain the detection result of user 2. Embodiment Consider an uplink system with a total number of users U = 2, an oversampling factor Q = 2, using QPSK modulation, the received power ratio of user 1 and user 2 is 4, the channel is a Gaussian channel, and the signal-to-noise ratio is 10 dB. The number of DFT-s-OFDM valid symbols N DFT = 8, the number of CE-OFDM valid symbols N c = 3, the number of subcarriers actually carrying information is N = 8, the oversampling factor is Q = 2, and the number of full-band subcarriers is N all = NQ = 16, and the frequency-domain selective fading channel is h i , i = 1, 2. Setting the energy consumption threshold α is equivalent to 50% of the power. Assuming that the power of user 2 is lower than 50%, then the more energy-efficient CE-OFDM waveform is used. When the base station receiver demodulates the CE-OFDM signal, phase demodulation (i.e., the arctangent demodulator) is selected. The method includes the following steps: Uplink user 1 transmitter: (DFT-s-OFDM process description) a1. Digital modulation: Map the information bits of user 1 to obtain a modulated signal after 2-QAM modulation Denoted as a2. DFT precoding and oversampling: Apply the modulated signal Generate the signal X through an 8-point DFT transform 1 , denoted as X 1 = [X 1 (1), X 1 (2), …, X 1 (8)] T Then perform oversampling to obtain a frequency-domain symbol of length 16 a3. Subcarrier mapping and IFFT conversion: Apply Generate the time-domain OFDM symbol of the first user through a 16-point IFFT transform The signal x at the nth sampling point of the user 1 Denoted as: x 1 = [x 1 (1), x 1 (2), …, x 1 (16)] T a4. Add CP: Add a cyclic prefix to obtain the transmitted signals of each user It can be expressed as: s 1 = [x 1

[0015] , x 1

[0016] , x 1 [1], x 1 [2], …, x 1

[0016] ] T Among them, the cyclic prefix length is 2; a5. Power configuration: Configure the transmission power of the transmitted signal s 1 of the proximal user to be Uplink user 2 transmitter: (CE-OFDM process description) b1. Digital modulation: Map the information bits of user 2 to obtain a modulated signal after 2-QAM modulation It is expressed as X 2 = [X 2 (1), X 2 (2), X 2 (3)] T b2. If the current energy consumption level is equal to or lower than the threshold, then generate the CE-OFDM waveform according to steps b3 - b6, and complete the power configuration according to b7. b3. Symmetric mapping: Place X 2 in the following conjugate symmetric format to obtain a frequency-domain symbol with a length of 16 That is b4. Frequency-domain to time-domain transformation: Transform through a 16-point IFFT transformation to generate the time-domain symbol of user 2 It is expressed as: x 2 = [x 2 (1), x 2 (2), x 2 (3), …, x 2 (14), x 2 (15), x 2 (16)] b5. Phase modulation: Obtain the discrete time-domain CE-OFDM signal by phase modulating the time-domain OFDM symbol x 2 [n] of user 2 Expressed as: s′ 2 = [s′ 2 (1), s′ 2 (2), s′ 2 (3), …, s′ 2 (14), s′ 2 (15), s′ 2 (16)] b6. Add CP: Add the cyclic prefix to obtain the transmitted signal of User 2 s 2 = [s′ 2 (15), s′ 2 (16), s′ 2 (1), s′ 2 (2), s′ 2 (3), …, s′ 2 (14), s′ 2 (15), s′ 2 (16)] T b7. Power configuration: Configure the transmitted power of the transmitted signal s of the remote user 2 to be Base station receiving end: c1. Time-domain to frequency-domain transformation: Remove the CP from the received signal and perform a 16-point FFT transformation to obtain the frequency-domain received signal Y = [Y(1), Y(2), …, Y(16)] T ; c2. Hybrid waveform data processing process: c2-1: The signal to be detected Y of User 1 1 = Y. According to the set waveform used by User 1 being DFT-s-OFDM, the base station first extracts the data at the corresponding positions in the frequency domain, then performs an IFFT transformation to the time domain, and finally performs M-order QAM demodulation to obtain the bit data of the first user. c2-2: To detect the data of the second user, first perform M-order QAM modulation, DFT, oversampling, and IFFT on the bit data of User 1 in sequence to obtain s′ 1 , and then perform an FFT transformation to the frequency-domain signal S′ 1 . After canceling the interference of User 1 from the received signal and then dividing by the corresponding power factor, obtain the signal to be detected of User 2 Expressed as follows: c2-3: When the base station does not know whether the waveform selected by User 2 is DFT-s-OFDM or CE-OFDM, it is first assumed that it is the DFT-s-OFDM waveform of the user. Take as the signal Y to be detected of User 2 2 . The base station extracts the data at the corresponding position in the frequency domain, then transforms it to the time domain through IFFT, and finally performs M-order QAM demodulation to obtain the first alternative bit data of the user Then remap and generate the DFT-s-OFDM signal according to steps a1-a3 Then transform to the frequency domain to obtain Finally, calculate the Euclidean distance c2-4: Assume it is the CE-OFDM waveform of the user. If the performance requirement is not high, then perform Step 1 to first transform Y 2 to the time domain for phase demodulation (i.e., arctangent demodulation), then perform FFT transformation, extract the data at the corresponding position, and perform M-order QAM demodulation to obtain the second alternative bit data of User 2 Then remap and generate the CE-OFDM signal according to steps b1-b5 Then transform to the frequency domain to obtain Finally, calculate the Euclidean distance Compare ε 1 and ε 2 , ε 1 > ε 2 , then the detection result of User 2 is Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the creative concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An energy consumption-based adaptive non-orthogonal uplink multiple access method. In a wireless communication system including CE-OFDM modulation and DFT-s-OFDM modulation, the number of valid symbols of DFT-s-OFDM modulation is N DFT , the number of valid symbols of CE-OFDM modulation is N c , the number of subcarriers carrying information at the transmitter is N, the oversampling factor is Q, and the number of subcarriers in the full frequency band N all = NQ. The users at the transmitter are paired in pairs by the system. The two users in each pair of users are divided into a proximal user and a distal user based on the distance between their transmitter and the receiver. The system configures a corresponding power weight for each pair of users. The power weight of the proximal user is denoted as P 1 , and the power weight of the distal user is denoted as P 2 , Among them, 0 ≤ P 2 ≤ P 1 ≤ 1, and P 1 + P 2 = 1; characterized in that, the method comprises: the transmission waveform of the proximal user adopts the DFT-s-OFDM waveform, and the distal user determines its transmission waveform according to the current energy consumption level of the transmitter: if the energy consumption level is greater than the preset energy consumption threshold of the system, the DFT-s-OFDM waveform is adopted; if the energy consumption level is less than or equal to the energy consumption threshold, the CE-OFDM waveform is adopted; The signal transmission steps when the transmitter adopts the DFT-s-OFDM waveform include: Step a1. Digital modulation: Map the information bits to be transmitted to M-QAM modulation to obtain a modulation signal with a symbol length of N DFT of the modulation signal Step a2. DFT precoding and oversampling: The modulated signal Generate signal X through N-point DFT DFT ; Oversample signal X 1 to obtain a frequency-domain signal with a symbol length of N 1 all ​​ Step a3. IFFT conversion after subcarrier mapping: The frequency-domain signal Generate the time-domain OFDM signal x with a symbol length of N through the N-point IFFT transform all all 1 ;​​ Step a4. Add a cyclic prefix: For the signal x 1 add a cyclic prefix with a length of N CP to obtain the transmitted signal s of the current user at the transmitting end 1 ; Step a5. Power configuration: If the current transmitting end user is a near-end user, then based on the transmit power P allocated by the system t configure the transmit power of the transmit signal s of the near-end user 1 to be If the current transmitting-end user is a remote user, then based on the transmit power P allocated by the system t Configure the transmit signal s of the remote user 1 The transmit power of is The signal transmission steps when the transmitter adopts the CE-OFDM waveform include: Step b1. Digital modulation: Map the information bits to be transmitted to M - order QAM modulation to obtain a modulation signal X with a symbol length of N c ; 2 ; Step b2. Symmetric mapping: Place the modulation signal X in accordance with a predetermined conjugate symmetric format 2 to obtain a frequency-domain signal with a symbol length of N all ​ Step b3. Frequency-domain to time-domain transformation: For the frequency-domain signal Perform N all -point IFFT transformation to generate a time-domain OFDM symbol x all with a symbol length of N 2 ; Step b4. Phase modulation: Modulate the time-domain OFDM symbol x 2 to obtain a discrete time-domain symbol of length N all through phase modulation CE-OFDM signal s′ 2 ; Step b5. Add a cyclic prefix: For the signal s′ 2 add a cyclic prefix with a length of N CP to obtain the transmitted signal s of the current transmitting-end user 2 ; Step a6. Power configuration: Based on the transmit power P allocated by the system t configure the transmit signal s of the remote user 2 with a transmit power of The signal reception and processing steps of the receiver include: Step c1. Time-domain to frequency-domain transformation: Remove the cyclic prefix of the received signal, perform serial-to-parallel conversion, and then obtain the frequency-domain received signal Y through an N all -point FFT transformation; Step c2. Hybrid waveform data processing: Step c2-1. Equalize the frequency-domain received signal Y to obtain an equalized symbol with a symbol length of N all of the equalized symbol and use it as the signal Y to be detected for the proximal user in the current user pair 1 ; Treat the signal Y to be detected 1 Perform subcarrier demapping processing, then transform to the time domain through IDFT, and perform M-order QAM demodulation after serial-to-parallel conversion to obtain the bit data U of the proximal user 1 ; Step c2-2. Compare bit data U 1 Perform M-order QAM modulation, DFT, oversampling, and IFFT on it in sequence to obtain signal s′ 1 Then convert it into a frequency-domain signal S′ through FFT 1 ; Based on interference cancellation, the signal to be detected of the remote user is obtained Among them, represents the channel estimation result from the proximal user to the receiver; Signal to be detected After equalization processing, it is used as the signal Y to be detected by the remote user 2 ; Step c2-3. Obtain the first alternative bit data of the distal user under the DFT-s-OFDM waveform: Treat the signal Y to be detected 2 Perform subcarrier demapping processing, then transform to the time domain through IDFT, and perform M-order QAM demodulation after serial-to-parallel conversion to obtain the alternative bit data of the remote user Based on the alternative bit data again Remap according to steps a1 - a3 to generate a DFT - s - OFDM signal with a symbol length of N all ​ Then transform it to the frequency domain to obtain the frequency-domain signal And calculate the Euclidean distance Among them, represents the channel estimation result from the distal user to the receiver; Step c2-4. Based on the signal Y to be detected 2 Obtain the second alternative bit data of the remote user under the CE-OFDM waveform The corresponding transmitted symbol vector And calculate the corresponding Euclidean distance Step c2-5. Determine the bit data U of the final remote user based on the Euclidean distance 2 : If The transmission waveform of the remote user is the DFT-s-OFDM waveform, and the bit data U of the remote user 2 is If The transmission waveform of the remote user is a CE-OFDM waveform, and the bit data U of the remote user 2 is 2. The method according to claim 1, characterized in that In step c2-4, obtain the second alternative bit data of the remote user corresponding to the transmitted symbol vector in any of the following two ways: Method 1: Transfer Y 2 to the time domain for phase demodulation and then perform FFT transformation. After subcarrier demapping processing, perform M-order QAM demodulation to obtain the second alternative bit data of the remote user For alternative bit data Remap according to steps b1 - b4 to generate a CE - OFDM signal with a symbol length of N all ​ Then transform to the frequency domain to obtain Method 2: Define Ω as all possible transmitted symbol vectors before phase modulation when the remote user adopts the CE-OFDM waveform a set, the set Ω contains elements The vector dimension is 1×N all ; Find from the set Ω such that the Euclidean distance Minimum transmitted symbol vector And denote it as At the same time, corresponding to Euclidean distance Denoted as Will Convert the valid data in [[]] into the corresponding estimated bit sequence to obtain the bit data of the remote user 3. The method according to claim 1 or 2, characterized in that In step b2, the frequency-domain signal Specifically: Among them, the parameter N zp = N(Q - 1), (·) * represents conjugate, respectively represent dimensions of 1×zp and the zero vector.

4. The method according to claim 1 or 2, characterized in that In step b4, the n-th discrete-time domain CE-OFDM symbol s′ 2 of the signal s′ 2 [n] is specifically: φ 2 = 2πhC N x 2 [n]; Wherein, A is the amplitude of the carrier signal, 2πh is the modulation index, and h is the modulation index parameter preset by the system. is the normalization constant factor, and the symbol number n = 0, …, N all -1.

5. The method according to claim 1 or 2, characterized in that The power of the transmitter is used to characterize the energy consumption level of the distal user.

6. The method according to claim 1 or 2, characterized in that The power weight is denoted as P 1 and P 2 take values of 0.8 and 0.2 respectively.

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