A joint amplitude and coherent detection separate receiver signal detection method

Abstract

The present application belongs to the technical field of wireless communication, and particularly relates to a signal detection method of a separate receiver based on joint amplitude and coherent detection. The present application proposes a signal detection algorithm based on the separate receiver architecture of amplitude and coherent detection (ED-CD), and compares the performance with that of the separate receiver based on power and coherent detection (PD-CD). The solution of the present application is to divide the received signal into two paths by setting a power splitter, and the two paths of signals are processed by the coherent detection and amplitude detection circuits respectively, and the two paths of signals after processing are jointly used for information detection. The method of the present application can obtain a lower symbol error rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wireless communication, and particularly relates to a signal detection method of a separate receiver with joint amplitude and coherent detection. BACKGROUND

[0002] The rapid development of popular technologies such as mobile Internet, Internet of Things, machine type communication and artificial intelligence brings explosive growth of data traffic, high complexity of data structure and increasing mobility of communication interaction, and human society enters the era of big data. According to the Kuper law, the data traffic of wireless network increases by one time every 30 months, and Cisco estimates that the total global mobile data traffic will increase to 163 ZB by 2025, which is close to 10.2 times of the total amount in 2016. In order to cope with the exponential growth of data traffic and the needs of diversified application scenarios in the era of big data, people have carried out research on receiver, large-scale multiple input multiple output (MIMO), multiple access, full duplex, millimeter wave communication and air interface waveform and achieved a lot of results. Among them, the optimization design of receiver scheme as the first step of signal detection and estimation is the focus of academia and industry.

[0003] The receiver schemes of traditional wireless communication systems are divided into coherent receiver and non-coherent receiver. The coherent receiver based on coherent detection (CD) converts the radio frequency (RF) signal into the I and Q paths of the baseband signal through the down-conversion circuit first, then converts it into a digital signal through the analog to digital converter (ADC), and finally demodulates the signal. The coherent receiver has good demodulation performance and is widely used in various wireless communication systems. However, the coherent receiver needs to know the channel state information (CSI) when demodulating the signal. Since it is difficult to obtain the CSI in large-scale MIMO and millimeter wave communication systems, it brings challenges to the signal detection process. The non-coherent receiver based on non-coherent detection (ND) is favored again. The non-coherent receiver is mainly divided into the non-coherent receiver based on envelope detection (ED) and the non-coherent receiver based on power detection (PD). Among them, the circuit of the non-coherent receiver based on ED is generally a passive device, and the circuit of the non-coherent receiver based on PD generally contains active devices, so the power consumption of the non-coherent receiver based on ED is lower than that of the non-coherent receiver based on PD. The literature "LIU W, ZHOU X, DURRANI S, et al. A novel receiver design with joint coherent and non-coherent processing [J]. IEEE Transactions on Communications, 2017, 65(8): 3479-3493" and the literature "WANG Y, LIU W, ZHOU X, et al. On the performance of splitting receiver with joint coherent and non-coherent processing [J] IEEE Trans. Signal Process., vol. 68, pp. 917-930, Jan. 2020." design a split receiver structure based on power detection and coherent detection (PD-CD), but because the non-coherent detection branch uses power detection, it causes relatively large power loss.

[0004] The document "WANG Y, LIU W, ZHOU X. Splitting Receiver with Joint Envelope and Coherent Detection [J]. IEEE Communications Letters, 2022" proposes a splitting receiver structure with joint envelope and coherent detection (ED-CD), and analyzes the mutual information performance under this architecture, but does not analyze the signal detection performance under this system. SUMMARY

[0005] The purpose of the present application is to propose a signal detection algorithm based on the splitting receiver architecture of envelope and coherent detection (ED-CD) and compare it with the performance of the splitting receiver based on power and coherent detection (PD-CD). The solution of the present application is to set a power splitter to divide the received signal into two paths, and the two signals are processed by coherent detection and envelope detection circuits respectively, and the processed two signals are used for information detection.

[0006] The technical solution of the present application is:

[0007] A signal detection method of a splitting receiver with joint envelope and coherent detection, characterized in that it comprises:

[0008] The received signal is defined as:

[0009]

[0010] Where P is the average power of the transmitted signal, is the wireless channel, is the transmitted signal, is the antenna noise;

[0011] The signal is divided into two paths by a power splitter ρ, and is processed by a coherent detection circuit and a non-coherent detection circuit based on envelope detection, respectively, to obtain the received signal of the coherent detection branch and the received signal Y2' of the non-coherent detection branch; the joint received signals and Y2' are obtained, and finally the three-dimensional received signal under the splitting receiver scheme is obtained

[0012] Let Then the received signal is transformed into:

[0013]

[0014]

[0015] in, Y2 = Y2′, variable and N represent antenna noise, conversion noise of the coherent detection circuit, and rectifier noise of the incoherent detection circuit, respectively. The noise variances are expressed as: and

[0016] Detection of transmitted signals based on the maximum likelihood criterion:

[0017]

[0018] in, It is the detected transmission signal, Ω cons Given the set of signal constellation points, the solution method is as follows:

[0019] complex signals The real and imaginary parts are represented by Y. 1r and Y 1i Complex noise The real and imaginary parts are represented as W. r and W i ,but Redescribed as:

[0020]

[0021] in, To receive signals The conditional PDF satisfies the following distribution:

[0022]

[0023]

[0024] in The mean is variance is The complex Gaussian distribution; The mean is variance is The real Gaussian distribution; antenna noise probability density function The distribution that satisfies is in

[0025] The mean is 0 and the variance is Obtaining conditions and Then, W was respectively r and W i Integrate to find the solution. The value;

[0026] Estimating the transmitted signal based on ML criterion At this time, for First, calculate the conditional Then select the maximum Get the estimated transmitted signal

[0027] Further, when ignoring the antenna noise, the detection method for the transmitted signal is:

[0028] Simplify the received signal as:

[0029]

[0030]

[0031] Detect the transmitted signal based on the maximum likelihood criterion:

[0032]

[0033] Wherein

[0034]

[0035] Let Simplify the signal detection as:

[0036]

[0037] Thus, when detecting the transmitted signal, the problem of solving the maximum Is converted into the problem of solving the minimum distance detection.

[0038] The beneficial effects of the present application are: the method of the present application can obtain a lower symbol error rate, and the main advantage of the ED-CD separation receiver proposed by the present application is that the SER is almost the same as that of the PD-CD separation receiver, but the power loss of the proposed ED-CD separation receiver is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a structure diagram of the separation receiver scheme.

[0040] Figure 2 Considering the antenna noise, the performance comparison of the symbol error rate (SER) of the ED-CD separation receiver and the PD-CD separation receiver.

[0041] Figure 3 Without considering the antenna noise, the performance comparison of the symbol error rate (SER) of the ED-CD separation receiver and the PD-CD separation receiver. DETAILED DESCRIPTION

[0042] The technical solutions of the present application will be described clearly and completely below in combination with the drawings and simulation examples, so that those skilled in the art can better understand the present application.

[0043] The content of the present application is the design of a joint amplitude and coherent separation receiver structure under a wireless communication system and the analysis of the performance of signal detection under the structure, the focus being on the signal detection expression based on the separation receiver structure and the comparison of the signal detection performance with that under the traditional PD-CD separation receiver and coherent receiver, so as to obtain the signal detection performance of the proposed ED-CD separation receiver scheme. The separation receiver structure is shown in Fig. 1, when the non-coherent detection branch is amplitude detection, then Figure 1 Figure 1 is the ED-CD separation receiver, when Figure 1 the non-coherent detection branch is power detection, then Figure 1 is the PD-CD separation receiver.

[0044] The key equation used in the method of the present application is:

[0045]

[0046] wherein, represents the received signal obtained under the separation receiver architecture; ρ represents the power separation ratio, the value range of which is ρ∈[0,1]; represents the transmitted signal; P represents the average power of the transmitted signal; represents the antenna noise; and N represent the noise introduced by the coherent detection circuit and the non-coherent detection circuit respectively; is the wireless channel. According to the actual design of the non-coherent detection circuit, n generally takes the value of 1 or 2. When n=1, the non-coherent detection branch is a receiver scheme based on amplitude detection; when n=2, the non-coherent detection branch is a receiver scheme based on power detection. The present application designs n=1, i.e. a receiver scheme based on amplitude detection. When ρ=1, the separation receiver degenerates into a coherent receiver; when ρ=0, the separation receiver degenerates into a non-coherent receiver. Therefore, the classical coherent receiver and non-coherent receiver are special forms of the separation receiver scheme, and the present application can select different receiver schemes by setting the size of ρ.

[0047] The method of the present application comprises the following main steps:

[0048] Step 1, transmitting a signal through a wireless channel and reaching a receiving end;

[0049] ​Step 2, at the receiving end, the first received RF signal is contaminated by the antenna noise , and the contaminated signal is obtained Then the signal is divided into two paths by a power splitter, and the two paths of signals pass through a coherent detection circuit and a non-coherent detection circuit based on amplitude detection respectively. In the coherent detection circuit, the signal is first converted into a baseband signal, and then converted into a digital signal by an ADC; in the non-coherent detection circuit, the signal passes through a rectifier and a low-pass filter, and the amplitude of the output signal is obtained, and then converted into a digital signal by an ADC;

[0050] Step 3, in the coherent detection circuit and the non-coherent detection circuit, the influence of the post-processing noise and N is considered respectively, and the received signal of the coherent detection branch and the received signal of the non-coherent detection branch Y'2 are obtained; the joint received signals and Y'2 are obtained, and finally the three-dimensional received signal under the separated receiver scheme is obtained

[0051] Step 4, the signal detection performance of the system is analyzed according to the separated received signal The detailed solving process is as follows:

[0052] In the application, only the case of n=1 is considered, and an ED-CD separated receiver is used. In order to facilitate subsequent analysis, let Then formula (1) is transformed into:

[0053]

[0054] Wherein, Let the variables and N represent the antenna noise, the conversion noise of the coherent detection circuit and the rectifier noise of the non-coherent detection circuit respectively, and the noise variances are and

[0055] In order to verify the demodulation performance of the ED-CD separated receiver structure, the application first considers the influence of the antenna noise and the post-detection circuit noise according to the separated received signal model, designs an optimal signal detection algorithm based on the maximum likelihood (Maximum-Likelihood, ML) criterion, and then simplifies the received signal model by ignoring the influence of the antenna noise, and obtains a low-complexity signal detection algorithm. This scheme avoids solving double integrals, and can effectively reduce the calculation complexity of the detection algorithm.

[0056] The specific detection method of the application is:

[0057] (1) Optimal signal detection method

[0058] For a certain constellation modulation, the transmitted signal is equally distributed in two-dimensional space. When detecting the signal, the optimal signal detection method is ML detection. Assuming that the set of signal constellation points is represented as Ω cons , the transmitted signal is represented as:

[0059]

[0060] For convenience of calculation, the real part and the imaginary part of the complex signal are represented as Y 1r and Y 1i respectively, and the real part and the imaginary part of the complex noise are represented as W r and W i respectively. Then is re-described as:

[0061]

[0062] where is the conditional PDF of the received signal , which satisfies the distribution

[0063]

[0064] where represents a complex Gaussian distribution with mean and variance ; represents a real Gaussian distribution with mean and variance . The probability density function of the antenna noise satisfies the distribution , where the mean is 0 and the variance is After obtaining the conditions and , the values of can be solved by integrating W r and W i respectively. When estimating the transmitted signal based on the ML criterion, for , first calculate the conditional corresponding to all received signals, and then select the maximum to obtain the estimated transmitted signal

[0065] (2) Signal detection method for simplifying the structure of ED-CD separation receiver

[0066] If the antenna noise is only thermal noise, the noise power is generally much smaller than the noise introduced by the coherent receiver and the non-coherent receiver, so we can ignore the influence of the antenna noise on the received signal. At this time, equation (2) is simplified as

[0067]

[0068] According to equation (6), given the transmitted signal , the received signal and Y 2s are independent of each other. Then the PDF of the received signal can be simplified as:

[0069]

[0070] where Y 1rs and Y 1is represent the real part and the imaginary part of the received signal respectively. X r and X i represent the real part and the imaginary part of the transmitted signal respectively. The simplified signal detection algorithm based on the received signal can be expressed as:

[0071]

[0072] Let , then the signal detection algorithm of the above equation can be simplified as

[0073]

[0074] According to equations (7) and (8), when detecting the transmitted signal, the problem of solving the maximum is converted into the problem of solving the minimum distance detection, which can effectively reduce the computational complexity because it does not need to solve the double integral.

[0075] Simulation Example

[0076] In the simulation, a single-carrier system is considered, and channel coding and decoding are not considered. It is assumed that the channel state information is known, and it is not loss of generality to set it to 1, i.e. The modulation mode of the transmitted signal is a 64QAM scheme.

[0077] Figure 2 ED-CD separate receiver structure and PD-CD separate receiver structure under the condition of considering antenna noise. In the figure, the antenna noise variance, the noise variance of the coherent receiver and the noise variance of the non-coherent receiver are set to The transmit signal power P is set to 100, 200, 300 and 400 respectively. The SER of the ED-CD separated receiver is calculated by Figure 2 It can be seen that, under different power P, the SER of the ED-CD separated receiver is almost equal to that of the PD-CD separated receiver; and the SER of the separated receiver decreases first and then increases with the increase of the separation ratio p, and the minimum SER position corresponds to the optimal separation ratio p. Therefore, compared with the SER of the coherent receiver (p = 1) and the SER of the non-coherent receiver (p = 0), the separated receiver has a smaller SER, and the SER value under the separated receiver scheme decreases with the increase of the power P.

[0078] Figure 3 The performance comparison of the SER under the ED-CD separated receiver structure and the PD-CD separated receiver structure is shown in FIG. 3, where the noise variance introduced by the coherent receiver and the noise variance introduced by the non-coherent receiver are set to The transmit signal power P is set to 100, 200, 300 and 400 respectively. The SER of the ED-CD separated receiver is calculated by Figure 3 It can be seen that, under different power P, the SER of the ED-CD separated receiver is almost equal to that of the PD-CD separated receiver; and the SER of the separated receiver decreases first and then increases with the increase of the separation ratio p, and the minimum SER position corresponds to the optimal separation ratio p. Therefore, compared with the SER of the coherent receiver (p = 1) and the SER of the non-coherent receiver (p = 0), the separated receiver has a smaller SER, and the SER value under the separated receiver scheme decreases with the increase of the power P. -6 For example, when P = 400, the optimal separation ratio p is 0.95, and at this time the SER of the ED-CD separated receiver and the SER of the PD-CD separated receiver are both 4.7 x 10 -5 Therefore, compared with the SER of the coherent receiver (p = 1), the separated receiver has a smaller SER, thereby verifying the superiority of the separated receiver structure.

Claims

1. A method of joint amplitude and coherent detection of a separate receiver signal detection, characterized by, Comprising: Defining the received signal as: where P is the average power of the transmitted signal, is the wireless channel, is the transmitted signal, is the antenna noise; signal The signal is divided into two paths by a power divider p, and then passed through a coherent detection circuit and a non-coherent detection circuit based on amplitude detection, respectively, to obtain a received signal Y1′ of a coherent detection branch and a received signal Y2′ of a non-coherent detection branch; and a joint received signal and Y2′, and finally obtain a three-dimensional received signal under a separate receiver scheme Let The received signal is then transformed into: wherein Y2 = Y2', variable and N represent the antenna noise, the conversion noise of the coherent detection circuit and the rectifier noise of the non-coherent detection circuit, respectively, and the noise variances are expressed as and Detecting the transmitted signal based on the maximum likelihood criterion: wherein is the detected transmitted signal, Ω cons is the set of signal constellation points, the solution method is: The real and imaginary parts of the complex signal are denoted as Y 1r and Y 1i respectively, and the real and imaginary parts of the complex noise are denoted as W r and W i respectively, then is re-described as: wherein the conditional PDF of the received signal satisfying the distribution where denotes a complex Gaussian distribution with mean and variance denotes a real Gaussian distribution with mean and variance ; antenna noise The distribution satisfying where the mean is 0 and the variance is After obtaining the conditions and , the values of r and i are integrated, respectively, to solve ;​​ Estimating a transmitted signal based on an ML criterion At a time t, for First, the conditional PDF corresponding to all received signals is calculated Then the maximum The estimated transmitted signal is obtained 2. A joint amplitude and coherent detection separate receiver signal detection method according to claim 1, characterized in that, When the antenna noise is ignored, the detection method of the transmitted signal is: Simplifying the received signal as: Detecting the transmitted signal based on the maximum likelihood criterion: Wherein Let Simplifying signal detection to: Thus, in detecting the transmitted signal, the problem of solving a maximization is converted to that of solving a minimization problem.

Images