Method for realizing terahertz communication based on even frequency multiplication

Abstract

The invention provides a method for realizing terahertz communication based on even frequency multiplication, which ensures that original information is not lost by recoding a signal and pre-processing a modulation signal; and according to the amplitude of the received modulation signal, an anti-noise adjustment coefficient is calculated, and an optimal judgment threshold is set, so that the gain level of the signal after even frequency multiplication is improved, and the received signal can be normally demodulated. According to the method, the modulation signal is preprocessed in a signal conversion mode, it is guaranteed that the bandwidth of a baseband signal is not increased after the BPSK signal is subjected to even frequency multiplication, original information is not lost, and the BPSK signal can still be demodulated correctly.

Description

Technical Field

[0001] The invention relates to a method for high-speed data transmission, in particular to a method for realizing terahertz communication based on even frequency doubling, and belongs to the technical field of data communication. Background Art

[0002] With the development of science and technology, the terahertz wireless data transmission system has higher and higher requirements for the rate, and the current research rate can reach 1.1THz. The ultra-high-speed transmission system has also sharply increased the requirements for RF analog devices, but in practical applications, devices such as mixers cannot support such a high rate. Therefore, a frequency multiplier is needed as the final stage device in the RF transmission part to increase the final stage output power while reducing the performance requirements for the amplifier.

[0003] In response to the above application requirements, the research needs to use a method of directly doubling the frequency of the modulated signal to achieve high-speed signal transmission. The method of directly doubling the frequency of the modulated broadband signal has the advantages of simple structure, high output frequency, and high power, and can provide sufficient radiation energy for ultra-high-speed long-distance terahertz wireless communication. According to the performance indicators and transmission rate requirements of the mixer, the frequency doubling of the modulated signal is different. According to the indicators and device requirements, there is a situation where the modulated signal is multiplied by an even power. Because the unipolar encoding method has the disadvantages of being difficult to implement, poor anti-noise performance, and not conducive to extraction during baseband signal transmission, the bipolar non-return-to-zero encoding method is generally used during signal transmission. However, after the bipolar signal is multiplied by an even power, information will be lost, resulting in the inability to correctly demodulate the original signal. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a method for realizing terahertz communication based on even frequency doubling, to pre-process the modulated signal by signal conversion, to ensure that the baseband signal bandwidth of the BPSK signal does not increase after even frequency doubling, the original information is not lost, and it can still be correctly demodulated.

[0005] The technical solution of the present invention is:

[0006] A method for realizing terahertz communication based on even frequency doubling comprises the following steps:

[0007] Step 1: Re-encode the signal to be sent to obtain a new signal S;

[0008] Step 2: Perform 2PSK modulation on the coded signal S to obtain a modulated signal S_2PSK;

[0009] Step 3: Process the modulated signal S_2PSK to obtain a processed modulated signal S_2PSK_proc;

[0010] Step 4: directly perform even frequency multiplication on the processed modulated signal S_2PSK_proc;

[0011] Step 5: The baseband processing part at the receiving end generates an adjustment coefficient p according to the received signal distribution and sets a decision threshold T;

[0012] Step 6: Demodulate the received even-frequency-multiplied signal according to the decision threshold T to realize terahertz communication based on even-frequency-multiplied signal.

[0013] Furthermore, the signal to be sent is re-encoded, and the signal to be sent is a digital baseband signal. The specific encoding method is:

[0014] When the digital baseband signal is the binary code "0", S = A1;

[0015] When the digital baseband signal is binary code "1", S = A2;

[0016] Wherein, A1 and A2 are integers greater than or equal to 1, and A2>A1.

[0017] Furthermore, the coded signal S is modulated by 2PSK, and the specific method is as follows:

[0018] (1) The expression of 2PSK modulation signal is:

[0019] S_2psk(t)=Acos(2πf c t+θ(t)) (1)

[0020] Among them, S_2psk(t) is the waveform of 2PSK, A is the signal amplitude, f c is the carrier signal frequency, θ(t) represents the phase of the signal changing with time t;

[0021] (2) The signal after 2PSK modulation according to the 2PSK modulation signal expression is as follows:

[0022]

[0023] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0024] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0025] Further, the modulated signal S_2PSK is processed to obtain a processed modulated signal S_2PSK_proc, specifically:

[0026] S_2psk_proc(t)=S_2psk(t)+f(f c ,t) (3)

[0027] where f(f c ,t) is about frequency f c and time t, let f(f c ,t) is a constant A3, that is

[0028] f(f c ,t)=A3 (4)

[0029] The processed modulated signal is:

[0030]

[0031] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0032] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0033] Furthermore, the processed modulated signal S_2PSK_proc is directly subjected to even frequency multiplication, specifically:

[0034] After multiplying the processed modulated signal S_2psk_proc(t) 2k times, k ≥ 1, we get:

[0035]

[0036] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0037] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0038] Furthermore, when k=1, the signal after doubling is:

[0039]

[0040] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0041] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0042] Furthermore, the baseband processing part at the receiving end generates an adjustment coefficient p according to the received signal distribution and sets a decision threshold T, specifically:

[0043] When the baseband processing part of the terahertz receiving end receives a signal, a judgment threshold is generated according to A1, A2, and A3, and p is a threshold adjustment coefficient. The judgment threshold is dynamically adjusted according to the actual situation;

[0044] The threshold value T is calculated according to the following formula:

[0045]

[0046] T=pT1 (9)

[0047] Adjust the p value according to the actual channel quality.

[0048] Furthermore, the demodulation of the received even frequency-multiplied signal according to the decision threshold T is specifically as follows:

[0049] The baseband processing part of the terahertz receiving end restores the original baseband signal based on the demodulated signal R and the judgment threshold T.

[0050] (1) If R is located at [T, T2], the recovered baseband signal is "1";

[0051] (2) If R is in [0, T], further judgment is made based on the retained phase information:

[0052] θ(t) = 0, then the recovered baseband signal is "0";

[0053] θ(t)=π, then the recovered baseband signal is "1".

[0054] In a second aspect, the present invention further proposes a non-volatile storage medium, comprising: a computer program product, which, when executed, executes the method for realizing terahertz communication based on even frequency doubling.

[0055] In a third aspect, the present invention further proposes a computer program product, which, when executed by a processor, implements the method for realizing terahertz communication based on even frequency doubling.

[0056] The advantages of the present invention compared with the prior art are:

[0057] In the traditional method, the amplitude and phase of the original signal will undergo serious nonlinear distortion. From the spectrum, it can be seen that the bandwidth of the signal is significantly widened. Due to the periodicity of the signal, the phase signal is lost after even frequency doubling and cannot be demodulated normally. The present invention re-encodes the transmission signal in the baseband processing part of the transmitting end, and processes the modulated signal so that the original phase information is still retained after even frequency doubling. Moreover, due to the different coding amplitudes, when the transmission baseband is different, the received signal value range is also different. Therefore, by generating a dynamically modulated threshold in the baseband processing part of the receiving end, the demodulation of the signal after even frequency doubling can be achieved. Compared with the current prior art, the present invention has the following differences and improvements:

[0058] (1) The present invention adopts a method of directly multiplying the frequency of the modulated signal, which solves the problem of limited RF analog devices and reduces the requirements for analog devices such as mixers and amplifiers, which is conducive to realizing ultra-high-speed signal transmission.

[0059] (2) The present invention solves the problem of even frequency conversion information loss by re-encoding the baseband signal and processing the modulated signal.

[0060] (3) The present invention generates a threshold adjustment coefficient at the receiving end, and the anti-noise performance of the system can be improved through the adjustable threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the overall block diagram of the terahertz baseband processing system;

[0062] Figure 2 A schematic diagram of a method for realizing terahertz communication based on even frequency doubling;

[0063] Figure 3 This is the time domain diagram after 2PSK modulation;

[0064] Figure 4 This is the time domain diagram of the modulated signal after being processed and doubled in frequency. DETAILED DESCRIPTION

[0065] The following is a detailed description with reference to the accompanying drawings and specific implementations.

[0066] Aiming at the problem that the original information is lost and the demodulation cannot be performed correctly due to the signal superposition after the modulated signal is directly even-multiplied, the present invention re-encodes the signal and processes the modulated signal, calculates the anti-noise adjustment coefficient according to the received signal level, sets the optimal threshold, and improves the gain level of the signal after even-multiplied frequency, thereby ensuring the normal demodulation of the signal. Figure 1 Shown is the overall block diagram of the terahertz baseband processing system.

[0067] like Figure 2 As shown, the present invention proposes a method for realizing terahertz communication based on even frequency doubling, comprising the following steps:

[0068] Step 1: Re-encode the signal to be sent to obtain a new signal S;

[0069] The specific encoding method is:

[0070] When the digital baseband signal is the binary code "0", S = A1;

[0071] When the digital baseband signal is binary code "1", S = A2;

[0072] Wherein, A1 and A2 are integers greater than or equal to 1, and A2>A1.

[0073] Step 2: Perform 2PSK modulation on the coded signal S to obtain a modulated signal S_2psk;

[0074] (2.1) The expression of 2PSK modulation signal is:

[0075] S_2psk(t)=Acos(2πf c t+θ(t)) (1)

[0076] Among them, S_2psk(t) is the waveform of 2PSK, A is the signal amplitude, f c is the carrier signal frequency, θ(t) represents the phase of the signal changing with time t;

[0077] (2.2) The signal after 2PSK modulation according to the 2PSK modulation signal expression is as follows:

[0078]

[0079] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0080] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0081] Step 3: Process the modulated signal S_2PSK to obtain a processed modulated signal S_2PSK_proc;

[0082] Specifically:

[0083] S_2psk_proc(t)=S_2psk(t)+f(f c ,t) (3)

[0084] where f(f c ,t) is about frequency f c and time t, design a suitable f(f c ,t) signal can solve the nonlinear problem caused by the frequency doubler and the signal amplitude disappearance problem caused by the even frequency doubler. In special cases, f(f c ,t) can also be a constant, let f(f c ,t) is a constant A3, that is

[0085] f(f c ,t)=A3 (4)

[0086] The processed modulated signal is:

[0087]

[0088] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0089] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0090] Step 4: directly perform even frequency multiplication on the processed modulated signal S_2PSK_proc;

[0091] After multiplying the processed modulated signal S_2psk_proc(t) 2k times, k ≥ 1, we get:

[0092]

[0093] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0094] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0095] Step 5: The baseband processing part at the receiving end generates an adjustment coefficient p according to the received signal distribution and sets a decision threshold T;

[0096] When the baseband processing part of the terahertz receiving end receives a signal, a judgment threshold is generated according to A1, A2, and A3, and p is a threshold adjustment coefficient. The judgment threshold is dynamically adjusted according to the actual situation;

[0097] The threshold value T is calculated according to the following formula:

[0098]

[0099] T=pT1 (9)

[0100] Adjust the p value according to the actual channel quality.

[0101] Step 6: Demodulate the received even-frequency-multiplied signal according to the decision threshold T to realize terahertz communication based on even-frequency-multiplied signal.

[0102] The baseband processing part of the terahertz receiving end restores the original baseband signal based on the demodulated signal R and the judgment threshold T.

[0103] (1) If R is located at [T, T2], the recovered baseband signal is "1";

[0104] (2) If R is in [0, T], further judgment is made based on the retained phase information:

[0105] θ(t) = 0, then the recovered baseband signal is "0";

[0106] θ(t)=π, then the recovered baseband signal is "1".

[0107] Example:

[0108] For the 2-fold frequency 2PSK modulation signal, a method for realizing terahertz communication based on even frequency doubling mainly consists of the following steps:

[0109] Step 1: The baseband processing part at the transmitting end re-encodes the baseband signal to be transmitted to obtain a new signal S.

[0110] When the digital baseband signal is the binary code "0", S = A1;

[0111] When the digital baseband signal is binary code "1", S = A2;

[0112] Wherein, A1 and A2 are integers greater than or equal to 1, and A2>A1.

[0113] Step 2: The encoded signal is modulated by 2PSK;

[0114] Assume S_2psk(t) is the waveform of 2PSK, f c is the carrier signal frequency, and θ(t) represents the phase of the signal changing with time.

[0115] The signal after 2psk modulation is as follows:

[0116]

[0117] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0118] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0119] When A1=1, A2=3, the time domain diagram of the modulated signal of the present invention is as shown in the attached figure. Figure 3 As shown:

[0120] Step 3: Process the modulated signal so that the information is not lost after the modulated signal is evenly multiplied;

[0121] The modulated signal after preprocessing is:

[0122] S_2psk_proc(t)=S_2psk(t)+f(f c ,t)

[0123] where f(f c ,t) is about frequency f c and time t, design a suitable f(f c ,t) signal can solve the nonlinear problem caused by the frequency doubler and the signal amplitude disappearance problem caused by the even frequency doubler. In this specific implementation, f(f c ,t)=A3, A3 is a constant; in this case, the modulated signal is:

[0124]

[0125] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0126] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0127] Step 4: Directly even-multiply the frequency of the processed modulated signal;

[0128] After doubling the frequency of the processed modulated signal, we can get:

[0129]

[0130] If the transmitted baseband signal is binary "0", then θ(t) = 0;

[0131] If the transmitted baseband signal is binary "1", then θ(t) = π.

[0132] Attached Figure 4 This is the time domain diagram of the modulated signal after being processed and doubled in frequency.

[0133] According to the above formula and attached Figure 4 It can be seen that the original phase information is still retained after doubling the frequency, and because A2>A1, when the transmitted baseband signal is different, the received signal value range is also different. When A1=1, A2=3, A3=1, the data with amplitude values ​​between 4 and 16 has an original signal of 1; the data with amplitude values ​​between 0 and 4 can further determine the original signal based on the retained phase information. Therefore, the original baseband signal information is not lost after the modulated signal is doubled in the present invention.

[0134] Step 5: At the receiving end, the baseband processing part generates an adjustment coefficient p according to the received signal distribution and sets a threshold T;

[0135] When the baseband processing part of the terahertz receiving end receives a signal, a judgment threshold is generated according to A1, A2, and A3, and p is a threshold adjustment coefficient. The threshold can also be dynamically adjusted according to actual conditions.

[0136] Typically, the threshold value T is calculated using the following formula.

[0137] T1=A1 2 +A3 2 +2A1A3

[0138] T2=A2 2 +A3 2 +2A2A3

[0139] T=pT1

[0140] The p value can be adjusted according to the actual channel quality. Generally, p=1.

[0141] Step 6: Demodulate the received frequency-multiplied signal according to the threshold T.

[0142] The baseband processing part of the terahertz receiving end restores the original baseband signal based on the demodulated signal R and the threshold T.

[0143] (1) If R is located at [T, T2], the recovered baseband signal is "1".

[0144] (2) If R is in [0, T], further judgment is made based on the retained phase information.

[0145] ·θ(t)=0, the recovered baseband signal is “0”;

[0146] ·θ(t)=π, the recovered baseband signal is "1".

[0147] At this point, the process of realizing terahertz communication based on even frequency doubling is completed.

[0148] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A method for realizing terahertz communication based on even frequency doubling, characterized in that include: Re-encode the signal to be sent to obtain a new signal S; Perform 2PSK modulation on the coded signal S to obtain a modulated signal S_2PSK; Processing the modulated signal S_2PSK to obtain a processed modulated signal S_2PSK_proc; Directly perform even frequency multiplication on the processed modulated signal S_2PSK_proc; The baseband processing part at the receiving end generates an adjustment coefficient p according to the received signal distribution and sets the decision threshold T; The received even-frequency-multiplied signal is demodulated according to the decision threshold T to realize terahertz communication based on even-frequency-multiplied signal.

2. The method for realizing terahertz communication based on even frequency doubling according to claim 1, characterized in that: The signal to be sent is re-encoded, and the signal to be sent is a digital baseband signal. The specific encoding method is: When the digital baseband signal is binary code "0", make S = A1; When the digital baseband signal is binary code "1", S = A2; Wherein, A1 and A2 are integers greater than or equal to 1, and A2>A1.

3. The method for realizing terahertz communication based on even frequency doubling according to claim 2, characterized in that: The coded signal S is modulated by 2PSK, and the specific method is as follows: (1) The expression of 2PSK modulation signal is: S_2psk(t)=Acos(2πf c t+θ(t)) (1) Among them, S_2psk(t) is the waveform of 2PSK, A is the signal amplitude, f c is the carrier signal frequency, θ(t) represents the phase of the signal changing with time t; (2) The signal after 2PSK modulation according to the 2PSK modulation signal expression is as follows: If the transmitted baseband signal is binary "0", then θ(t) = 0; If the transmitted baseband signal is binary "1", then θ(t) = π.

4. The method for realizing terahertz communication based on even frequency doubling according to claim 1, characterized in that: The modulated signal S_2PSK is processed to obtain a processed modulated signal S_2PSK_proc, specifically: S_2psk_proc(t)=S_2psk(t)+f(f c ,t) (3) where f(f c ,t) is about frequency f c and time t, let f(f c ,t) is a constant A3, that is f(f c ,t)=A3 (4) The processed modulated signal is: If the transmitted baseband signal is binary "0", then θ(t) = 0; If the transmitted baseband signal is binary "1", then θ(t) = π.

5. The method for realizing terahertz communication based on even frequency doubling according to claim 1, characterized in that: The processed modulated signal S_2PSK_proc is directly subjected to even frequency multiplication, specifically: After multiplying the processed modulated signal S_2psk_proc(t) 2k times, k ≥ 1, we get: If the transmitted baseband signal is binary "0", then θ(t) = 0; If the transmitted baseband signal is binary "1", then θ(t) = π.

6. The method for realizing terahertz communication based on even frequency doubling according to claim 5, characterized in that: When k=1, the signal after doubling is: If the transmitted baseband signal is binary "0", then θ(t) = 0; If the transmitted baseband signal is binary "1", then θ(t) = π.

7. The method for realizing terahertz communication based on even frequency doubling according to claim 4, characterized in that: The baseband processing part at the receiving end generates an adjustment coefficient p according to the received signal distribution and sets the decision threshold T, which is specifically: When the baseband processing part of the terahertz receiving end receives a signal, a judgment threshold is generated according to A1, A2, and A3, and p is a threshold adjustment coefficient. The judgment threshold is dynamically adjusted according to the actual situation; The threshold value T is calculated according to the following formula: T=pT1 (9) Adjust the p value according to the actual channel quality.

8. The method for realizing terahertz communication based on even frequency doubling according to claim 7, characterized in that: The demodulation of the received even frequency-multiplied signal according to the decision threshold T is specifically as follows: The baseband processing part of the terahertz receiving end restores the original baseband signal based on the demodulated signal R and the judgment threshold T. (1) If R is located at [T, T2], the recovered baseband signal is "1"; (2) If R is in [0, T], further judgment is made based on the retained phase information: θ(t) = 0, then the recovered baseband signal is "0"; θ(t)=π, then the recovered baseband signal is "1".

9. A non-volatile storage medium, characterized in that: include: A computer program product, when executed, performs the method for realizing terahertz communication based on even frequency doubling as described in any one of claims 1 to 8.

10. A computer program product, characterized in that When the computer program product is executed by a processor, the method for realizing terahertz communication based on even frequency doubling as claimed in any one of claims 1 to 8 is realized.

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