A method for realizing terahertz communication based on even frequency multiplication

Abstract

The application provides a method for realizing terahertz communication based on even frequency multiplication. The original information is not lost by re-encoding the signal and pre-processing the modulated signal. The anti-noise adjustment coefficient is calculated according to the amplitude of the received modulated signal, and the best decision threshold is set, so as to improve the gain level of the signal after even frequency multiplication, and make the received signal be able to be normally demodulated. The method pre-processes the modulated signal by signal transformation, guarantees that the baseband signal bandwidth is not increased after the BPSK signal is subjected to even frequency multiplication, the original information is not lost, and the BPSK signal can still be correctly demodulated.

Description

TECHNICAL FIELD

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

[0002] With the development of science and technology, the requirement for the rate of a terahertz wireless data transmission system is higher and higher, and the current research rate can reach 1.1 THz. The super-high-speed transmission system also sharply increases the requirement for radio frequency analog devices, but in actual application, a frequency mixer and the like cannot support such a high rate, so a frequency multiplier needs to be used as a final-stage device in the radio frequency transmitting part, so as to improve the output power of the final stage and reduce the performance requirement for an amplifier.

[0003] In view of the above application requirement, the research needs to adopt a mode of directly multiplying the modulated signal to realize high-speed rate transmission of the signal, and the mode of directly multiplying the modulated wideband signal has the advantages of simple implementation structure, high output frequency and large power, and can provide sufficient radiation energy for super-high-speed long-distance terahertz wireless communication. According to the performance index of the frequency mixer and the transmission rate requirement, the frequency multiplication times of the modulated signal are different. According to the index and the device requirement, there is a case of even frequency multiplication of the modulated signal. Since the single-polarity coding mode exists the problems of being difficult to realize, poor anti-noise performance and being not conducive to extraction when the baseband signal is transmitted, the bipolar non-return-to-zero coding mode is generally used when the signal is transmitted. However, after the bipolar signal is subjected to even frequency multiplication, information is lost, so that the original signal cannot be correctly demodulated. SUMMARY

[0004] The application solves the technical problem that the prior art has the shortcomings, and provides a method for realizing terahertz communication based on even frequency multiplication, which pre-processes the modulated signal through signal transformation, ensures that the baseband signal bandwidth is not increased after the BPSK signal is subjected to even frequency multiplication, the original information is not lost, and the original signal can still be correctly demodulated.

[0005] The technical scheme of the application is as follows:

[0006] A method for realizing terahertz communication based on even frequency multiplication, comprising the following steps:

[0007] Step 1: re-encoding a signal to be transmitted to obtain a new signal S;

[0008] Step 2: 2PSK modulating the encoded signal S to obtain a modulated signal S_2PSK;

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

[0010] Step 4: Directly doubling the frequency of the processed modulated signal S_2PSK_proc;

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

[0012] Step 6: Demodulating the received doubled frequency signal according to the decision threshold T, to realize terahertz communication based on doubled frequency.

[0013] Further, the signal to be transmitted is re-encoded, and the signal to be transmitted is a digital baseband signal, and the specific encoding method is:

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

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

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

[0017] Further, the encoded signal S is 2PSK modulated, and the specific method is as follows:

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

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

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

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

[0022]

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

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

[0025] Further, the modulated signal S_2PSK is processed to obtain the processed modulated signal S_2PSK_proc, and the specific method is:

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

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

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

[0029] The processed modulation 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] Further, the processed modulation signal S_2PSK_proc is directly doubled in frequency, specifically:

[0034] After the processed modulation signal S_2psk_proc(t) is doubled in frequency for k 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] Further, when k = 1, the signal doubled in frequency 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] Further, the adjustment coefficient p is generated according to the received signal distribution in the receiving end baseband processing part, and the decision threshold T is set, specifically:

[0043] When the receiving end baseband processing part 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] The value of p is adjusted according to the actual channel quality.

[0048] Further, the received even frequency doubled signal is demodulated according to the decision threshold T, specifically:

[0049] The baseband processing part of the terahertz receiving end recovers the original baseband signal according to the demodulation signal R and the discrimination threshold T,

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

[0051] (2) If R is located in [0, T], further judgment is made according to the reserved phase information:

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

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

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

[0055] In a third aspect, the application further provides a computer program product, when the computer program product is executed by a processor, realizes the method for realizing terahertz communication based on even frequency doubling.

[0056] Compared with the prior art, the application has the following advantages:

[0057] The amplitude and phase of the original signal in the conventional method will be severely nonlinearly distorted, and the bandwidth of the signal can be seen to be significantly widened from the spectrum, and due to the periodicity of the signal, the phase signal is lost after even frequency doubling, and cannot be normally demodulated. In the application, the transmitting signal is re-encoded in the baseband processing part of the transmitting end, and the modulated signal is processed, so that the original phase information is still reserved after even frequency doubling, and due to the different coding amplitudes, the signal value range received is different when the transmission baseband is 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 realized. The application has the following differences and progress compared with the prior art:

[0058] (1) The application adopts a direct frequency doubling mode of the modulated signal, solves the problem of the limitation of the radio frequency analog device, reduces the requirements for the analog devices such as mixers and amplifiers, and is conducive to realizing ultra-high-speed signal transmission.

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

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

[0061] Figure 1 It is a general block diagram of a terahertz baseband processing system.

[0062] Figure 2 It is a schematic diagram of a method for realizing terahertz communication based on even frequency multiplication.

[0063] Figure 3 It is a time domain diagram after 2PSK modulation.

[0064] Figure 4 It is a time domain diagram after 2 frequency multiplication of the processed modulated signal. DETAILED DESCRIPTION

[0065] The following will be described in detail in combination with the drawings and specific embodiments.

[0066] In view of the problem that the signal superposition after direct even frequency multiplication of the modulated signal leads to loss of original information and incorrect demodulation, the present application re-encodes the signal and processes the modulated signal, calculates an anti-noise adjustment coefficient according to the received signal level, sets the best threshold, improves the gain level of the signal after even frequency multiplication, and ensures normal demodulation of the signal. Figure 1 It is a general block diagram of a terahertz baseband processing system.

[0067] As shown in the figure, Figure 2 The present application proposes a method for realizing terahertz communication based on even frequency multiplication, which comprises the following steps:

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

[0069] The specific encoding mode is:

[0070] When the digital baseband signal is 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: 2PSK modulate the encoded signal S to obtain a modulated signal S_2psk;

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

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

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

[0077] 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 the 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 a function of frequency f c and time t, and designing a suitable f(f c ,t) signal can solve the non-linear problem caused by the frequency multiplier and the signal amplitude disappearance problem caused by the even frequency multiplier. In special cases, f(f c ,t) can also be a constant, and let f(f c ,t) be a constant A3, i.e.

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

[0086] Then 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 even frequency multiplication of the processed modulated signal S_2PSK_proc;

[0091] After 2k times frequency multiplication of the processed modulated signal S_2psk_proc(t), k≥1, the following is obtained:

[0092]

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

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

[0095] Step 5: The adjustment coefficient p is generated according to the received signal distribution in the receiving end baseband processing part, and the decision threshold T is set;

[0096] When the signal is received by the terahertz receiving end baseband processing part, the judgment threshold is generated according to A1, A2, and A3, and p is the 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] The value of p is adjusted according to the actual channel quality.

[0101] Step 6: The received even frequency multiplied signal is demodulated according to the decision threshold T, and the terahertz communication based on even frequency multiplication is realized.

[0102] The original baseband signal is recovered by the terahertz receiving end baseband processing part according to the demodulated signal R and the judgment threshold T,

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

[0104] (2) If R is located in [0, T], further judgment is made according to the preserved 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] Embodiment:

[0108] For a 2 frequency multiplied 2psk modulated signal, a method for realizing terahertz communication based on even frequency multiplication mainly comprises the following steps:

[0109] Step 1: The baseband processing part of the sending end re-encodes the baseband signal to be sent to obtain a new signal S.

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

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

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

[0113] Step two: the coded signal is modulated by 2PSK;

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

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

[0116]

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

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

[0119] When A1=1 and A2=3, the time domain graph of the signal after modulation of the present application is as shown in the accompanying drawings: Figure 3

[0120] Step three: the modulated signal is processed so that the information of the modulated signal after even frequency multiplication is not lost;

[0121] The modulated signal after pre-processing is:

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

[0123] Wherein f(f c ,t) is a function about frequency f c and time t, and the non-linear problem caused by frequency multiplier and the problem of signal amplitude disappearance caused by even frequency multiplication can be solved by designing appropriate f(f c ,t) signal. In the specific implementation process, f(f c ,t)=A3, and A3 is a constant; in this case, the modulated signal is:

[0124]

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

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

[0127] Step four: processing the modulated signal directly doubles the frequency;

[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] Figure 1 is a schematic diagram of the modulated signal before processing. Figure 4 Figure 2 is a time domain graph of the modulated signal after processing.

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

[0134] Step five: generating an adjustment coefficient p in the baseband processing part of the receiving end according to the received signal distribution, and setting a threshold T.

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

[0136] Generally, the threshold value T is calculated according to the following formula.

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

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

[0139] T=pT1

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

[0141] Step six: demodulating the received doubled frequency signal according to the threshold T.

[0142] The baseband processing part of the terahertz receiving end recovers the original baseband signal according to the demodulation signal R and the threshold T.

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

[0144] (2) If R is located in [0, T], further judgment is made according to the reserved phase information,

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

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

[0147] So far, the process of realizing terahertz communication based on even frequency multiplication is completed.

[0148] The part not described in detail in the present application is common knowledge to those skilled in the art.

Claims

1. A method for realizing terahertz communication based on even frequency multiplication, characterized in that The method comprises the following steps: re-encoding the signal to be transmitted to obtain a new signal S; modulating the encoded signal S by 2PSK to obtain a modulated signal S_2PSK; processing the modulated signal S_2PSK to obtain a processed modulated signal S_2PSK_proc; directly performing even frequency multiplication on the processed modulated signal S_2PSK_proc; generating an adjustment coefficient p according to the signal distribution received at the baseband processing part of the receiving end, and setting a decision threshold T; demodulating the received even frequency multiplied signal according to the decision threshold T to realize terahertz communication based on even frequency multiplication; The re-encoding of the signal to be transmitted is a digital baseband signal, and the specific encoding method is as follows: when the digital baseband signal is binary code "0", 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; The 2PSK modulation of the encoded signal S is as follows: (1) The expression of the 2PSK modulated signal is as follows: S_2psk(t) = A cos(2πf c t + θ(t)) (1) where S_2psk(t) is a 2PSK waveform, A is a signal amplitude, f c is the carrier signal frequency, and θ(t) represents the phase of the signal as a function of time t; (2) The signal after 2PSK modulation according to the expression of the 2PSK modulated signal is as follows: if the transmitted baseband signal is binary "0", θ(t)=0; if the transmitted baseband signal is binary "1", θ(t)=π; The processing of the modulated signal S_2PSK to obtain the processed modulated signal S_2PSK_proc is as follows: S_2psk_proc(t) = S_2psk(t) + f(f c ,t) (3) where f(f c ,t) is a function of frequency f c and time t, let f(f c ,t) be a constant A3, i.e. f(f c t) = A3 (4) The processed modulated signal is as follows: if the transmitted baseband signal is binary "0", θ(t)=0; if the transmitted baseband signal is binary "1", θ(t)=π; The direct even frequency multiplication of the processed modulated signal S_2PSK_proc is as follows: After 2k frequency multiplication of the processed modulated signal S_2psk_proc(t), k≥1, the following is obtained: if the transmitted baseband signal is binary "0", θ(t)=0; if the transmitted baseband signal is binary "1", θ(t)=π. 2.The method of claim 1, wherein: When k=1, the signal after 2 frequency multiplication is as follows: if the transmitted baseband signal is binary "0", θ(t)=0; if the transmitted baseband signal is binary "1", θ(t)=π.

3. The method of claim 1, wherein the method is based on even harmonic generation for terahertz communication. The generation of the adjustment coefficient p according to the signal distribution received at the baseband processing part of the receiving end and the setting of the decision threshold T are as follows: 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) The value of p is adjusted according to the actual channel quality.

4. The method of claim 3, wherein the method is characterized by: The demodulation of the received even frequency multiplied signal according to the decision threshold T is as follows: The baseband processing part of the terahertz receiving end recovers the original baseband signal according to the demodulated signal R and the judgment threshold T, (1) If R is located in [T, T2], the recovered baseband signal is "1"; (2) If R is located in [0, T], further judgment is made according to the preserved phase information: θ(t)=0, then the recovered baseband signal is "0"; When θ(t)=π, the recovered baseband signal is "1".

5. A non-volatile storage medium, characterized by The method comprises the following steps: The computer program product, when executed, implements the method for realizing terahertz communication based on even frequency multiplication according to any one of claims 1-4.

6. A computer program product, characterised in that, The computer program product, when executed, implements the method for realizing terahertz communication based on even frequency multiplication according to any one of claims 1-4.

Images