A Phase Noise Trajectory Tracking and Suppression Method

Abstract

The present invention relates to a method for tracking and suppressing phase noise trajectories. The method includes: Step 1, mathematically characterizing the communication transmission signal, wireless propagation channel, and communication reception signal of a frequency-hopping cooperative system; Step 2, at the communication receiver, estimating the average channel fading and phase noise value in a synchronous hop, and performing phase noise trajectory tracking and suppression on the signal hop. The present invention uses synchronous hop information to estimate the phase noise trajectory of the signal hop, can effectively suppress the phase noise in the transmitter and receiver frequency oscillators, and has important guiding significance for suppressing radio frequency hardware errors in practical engineering.

Description

Technical Field

[0001] The present invention relates to the field of communications, and in particular to a method for tracking and suppressing phase noise trajectories. Background Art

[0002] In a frequency hopping cooperative system, the frequency hopping technology is used to avoid electromagnetic interference, and the cooperative interference technology is used to block illegal eavesdropping, which can provide high-quality security services for wireless communication systems; however, the hopping radio frequency carrier will cause significant phase noise at the transmitting and receiving frequency oscillators, resulting in distortion of the desired signal, degradation of the cooperative interference suppression performance, and deterioration of the communication receiving signal-to-noise ratio performance; therefore, how to effectively suppress the phase noise in the transmitting and receiving frequency oscillators is a problem that needs to be considered at present. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art, and provides a method for tracking and suppressing phase noise trajectories, which solves the deficiencies existing in the prior art.

[0004] The purpose of the present invention is achieved through the following technical solutions: A method for tracking and suppressing phase noise trajectories, the method comprising:

[0005] Step 1, perform mathematical characterization on the communication transmission signal, wireless propagation channel, and communication reception signal of the frequency hopping cooperative system;

[0006] Step 2, at the communication receiver, estimate the average channel fading and phase noise value in the synchronous hop, and perform phase noise trajectory tracking and suppression on the signal hop.

[0007] The specific steps of Step 1 include:

[0008] At the communication transmitter, the baseband desired signal and cooperative interference are weighted and superimposed, converted from digital to analog, and frequency hopping modulated before transmission. Denote the k-th hop radio frequency transmission signal as where x(t) and y(t) respectively represent the baseband desired signal and cooperative interference, P x and P y respectively represent the transmission powers of the two, f i represents the carrier frequency of the k-th hop signal, represents the transmission phase noise;

[0009] Assume that the transmission signal reaches the receiver after experiencing flat slow fading, and denote the channel fading as h;

[0010] At the communication receiver, perform frequency hopping synchronization on the frequency hopping received signal to obtain the digital baseband signal where represents the analog-to-digital conversion operation, w(t) represents the noise component, x[n], y[n], respectively represent x(t), y(t), in its discrete form, represents the discrete form of the baseband equivalent noise signal.

[0011] At the communication receiver, estimating the average channel fading and phase noise value in a synchronization hop includes:

[0012] Estimating the average channel fading and phase noise parameters of the synchronization hop according to the desired signal sequence and cooperative interference information known to the receiver, and obtaining the estimated values of the average signal fading and phase noise parameters as where N represents the number of symbols in each hop signal;

[0013] Set the estimated value The amplitude and phase of are respectively and Then and where |·| represents the modulus operation, and ∠(·) represents the phase operation.

[0014] The phase noise trajectory tracking and suppression for signal hops includes:

[0015] Using the estimated value of the (p - 1)th hop to track the average phase noise in the received signal of the pth hop and obtaining the estimated value of the average phase noise in the received signal of the pth hop as where, represents the average phase noise increment of the received signal of the pth hop compared to the signal of the (p - 1)th hop;

[0016] Using the average phase noise estimated value to perform phase noise suppression and cooperative interference separation, and obtaining the signal as

[0017]

[0018] The present invention has the following advantages: A phase noise trajectory tracking and suppression method, which uses synchronization hop information to estimate the phase noise trajectory of signal hops, can effectively suppress the phase noise in the transmitter and receiver frequency oscillators, and has important guiding significance for suppressing radio frequency hardware errors in practical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic flow diagram of the present invention;

[0020] Figure 2 is a simulation diagram of the bit error rate performance after phase noise suppression. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only some, rather than all, of the embodiments of this application. Components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the protection scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative efforts fall within the protection scope of this application. The following further describes the present invention with reference to the accompanying drawings.

[0022] As Figure 1 shown, the present invention specifically relates to a phase noise trajectory tracking and suppression method, which effectively suppresses the phase noise in the transmitting and receiving frequency oscillators at the cost of less resource consumption; specifically includes the following:

[0023] S1. Mathematically characterize the communication transmission signal, wireless propagation channel, and communication reception signal of the frequency hopping cooperation system;

[0024] S2. At the communication receiver, estimate the average channel fading and phase noise value in the synchronization hop;

[0025] S3. At the communication receiver, perform phase noise trajectory tracking and suppression on the signal hop.

[0026] Further, step S1 includes the following sub-steps:

[0027] S101. At the communication transmitter, the baseband desired signal and cooperative interference are weighted and superimposed, converted from digital to analog, and then transmitted after frequency hopping modulation. Denote the k-th hop radio frequency transmission signal as z k (t), and the expression is:

[0028]

[0029] where x(t) and y(t) respectively represent the baseband desired signal and cooperative interference, P x and P y respectively represent the transmission powers of the two, f i represents the carrier frequency of the k-th hop signal, represents the transmission phase noise.

[0030] S102. Assume that the transmitted signal arrives at the receiver after experiencing flat slow fading, and denote the channel fading as h.

[0031] S103. At the communication receiver, perform frequency hopping synchronization on the frequency hopping received signal to obtain the digital baseband signal rk [n], the mathematical expression is:

[0032]

[0033] where represents the analog-to-digital conversion operation, w(t) represents the noise component, x[n], y[n], respectively represent the discrete forms of x(t), y(t), and represents the discrete form of the baseband equivalent noise signal.

[0034] It can be found that the baseband desired signal and the cooperative interference contain transmit and receive phase noise terms, which will cause significant signal distortion.

[0035] Furthermore, in step S2, the desired signal sequence and the cooperative interference information in the synchronization hop are known to the receiver and can be used to estimate the average channel fading and phase noise parameters of the synchronization hop. Denote the estimated values of the average channel fading and phase noise parameters as The expression is:

[0036]

[0037] where N represents the number of symbols in each hop signal. The reason for the approximate (a) to hold is that the power of the baseband equivalent noise signal is much smaller than the power of the baseband desired signal, the cooperative interference, and the signal combined.

[0038] Denote the amplitude and phase of the estimated value as and respectively. Then and where |·| represents the modulus operation and ∠(·) represents the phase operation.

[0039] Furthermore, step S3 includes the following sub-steps:

[0040] S301. Design of the phase noise trajectory tracking and suppression algorithm, mainly based on two considerations: ① The phase error accumulation caused by phase noise in a short time is small, so there is no need to estimate the phase noise symbol by symbol. Suppressing the phase noise hop by hop can obtain better performance improvement; ② The Wiener phase noise process is a continuous-valued random process. The average phase noise in the received signal of the p-th hop can be tracked using the estimated value of the (p - 1)-th hop. Therefore, the estimated value of the average phase noise in the received signal of the p-th hop is:

[0041]

[0042] Among them, represents the average phase noise increment of the received signal in the p-th hop compared to the signal in the (p - 1)-th hop. Considering that Wiener phase noise is a random process with independent increments, it can be directly obtained through an exhaustive method to get an approximate optimal solution.

[0043] S302. Use the phase noise estimate value to perform phase noise suppression and cooperative interference separation. The obtained signal can be expressed as:

[0044]

[0045] Among them, the reason for the approximate (b) to hold is and the power of the noise component is much smaller than the power of the desired signal.

[0046] The above formula shows that after the phase noise suppression and cooperative interference separation operations, the phase noise in the desired signal can be effectively suppressed, and the cover signal can be approximately perfectly separated.

[0047] Perform performance simulation on the proposed phase noise trajectory tracking and suppression method. The simulation results are as Figure 2 shown. It can be found that when there is phase noise in the system but no phase noise suppression is performed, the system bit error rate will reach 50% and the communication link will be blocked. The classical least squares algorithm only uses synchronous hops for channel estimation and compensation. It can be found that when the normalized 3dB coherence bandwidth is less than 10 -7 , this method can better suppress phase noise; but as the phase noise level increases, the system bit error rate performance deteriorates sharply because at this time the phase error caused by phase noise accumulates quickly, and only using synchronous hops for channel compensation cannot meet the system performance requirements. For the phase noise suppression method proposed in this patent, the system bit error rate is much lower than that of the classical least squares method, verifying that the present invention has significant performance advantages.

[0048] Aiming at the problem that the hopping radio frequency carrier will cause significant phase noise at the transmitter and receiver frequency oscillators, and the phase noise in frequency hopping communication causes distortion of the desired signal and degradation of the cooperative interference suppression performance, deteriorating the communication received signal-to-noise ratio performance, the phase noise trajectory tracking and suppression method proposed by the present invention can, at the cost of relatively small resource consumption, improve the phase noise suppression ability in the transmitter and receiver frequency oscillators, and has important guiding significance for suppressing radio frequency hardware errors in practical engineering.

[0049] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments. Instead, it can be used in various other combinations, modifications, and improvements, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. Any changes and variations made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A phase noise trajectory tracking and suppression method, characterized in that: The method includes: Step 1, mathematically characterize the communication transmission signal, wireless propagation channel, and communication reception signal of the frequency hopping cooperation system; Step 2, at the communication receiver, estimate the average channel fading and phase noise value in the synchronous hop, and perform phase noise trajectory tracking and suppression on the signal hop; The performing phase noise trajectory tracking and suppression on the signal hop includes: Using the estimated value of the (p - 1)-th hop Tracking the average phase noise in the received signal of the p-th hop The estimated value of the average phase noise in the received signal of the p-th hop is obtained as where represents the average phase noise increment of the received signal of the p-th hop compared to the (p - 1)-th hop signal; Using the average phase noise estimate value Perform phase noise suppression and cooperative interference separation to obtain the signal as where N represents the number of symbols in each hop signal, and respectively represent the set estimate values of the amplitude and phase, represents the discrete form of the baseband equivalent noise signal, P x and P y respectively represent the transmission powers of the two, h is the channel fading, x[n], y[n], respectively represent the discrete forms of x(t), y(t), respectively.

2. The phase noise trajectory tracking and suppression method according to claim 1, characterized in that: The specific content of Step 1 includes: At the communication transmitter, the baseband desired signal and the cooperative interference are weighted and superimposed, then subjected to digital-to-analog conversion and frequency-hopping modulation before transmission. Denote the k-hop radio frequency transmission signal as where x(t) and y(t) represent the baseband desired signal and the cooperative interference respectively, and P x and P y represent the transmission powers of the two respectively, f i represents the carrier frequency of the k-hop signal, represents the transmitted phase noise; Assume that the transmitted signal reaches the receiver after experiencing flat slow fading, and denote the channel fading as h; At a communication receiver, frequency-hopping synchronization is performed on the frequency-hopping received signal to obtain a digital baseband signal where represents an analog-to-digital conversion operation, w(t) represents a noise component, x[n], y[n], respectively represent the discrete forms of x(t), y(t), , represents the discrete form of the baseband equivalent noise signal.

3. A phase noise trajectory tracking and suppression method according to claim 2, characterized in that: The estimating the average channel fading and phase noise value in the synchronous hop at the communication receiver includes: Estimate the average channel fading and phase noise parameters of the synchronous hop based on the expected signal sequence and cooperative interference information known to the receiver, and obtain the estimated values of the average signal fading and phase noise parameters as where N represents the number of symbols in each hop signal; Set the estimated value The amplitude and phase of are respectively and Then And where |·| represents the modulus operation and ∠(·) represents the phase operation.

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