阅读说明：本技术 一种基于二进制正交频移键控调制的消息驱动跳频通信方法 (Message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation ) 是由 宁晓燕 宁宇 孙志国 孙溶辰 于 2019-09-02 设计创作，主要内容包括：本发明属于无线通信技术领域,具体涉及提高了频谱利用率和频率跳变的随机性的一种基于二进制正交频移键控调制的消息驱动跳频通信方法,包括如下步骤：(1)由数字化信息源分帧；(2)消息驱动与2QFSK调制；(3)将调制完成的比特作IFFT,加入循环前缀,并串转换；(4)信源信息经步骤1-3后发送,经过信道到达接收端；(5)串并转换,去除循环前缀,做FFT运算；(6)根据波形所在的一对子信道解调出驱动比特。本发明提供的基于2QFSK调制和IFFT/FFT的跳频与消息驱动跳频技术相结合,相较于传统跳频技术明显提升了频谱效率,相较于消息驱动跳频技术本发明具有更简单的解调方法和一定的抗噪性能提升。(The invention belongs to the technical field of wireless communication, and particularly relates to a message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation, which improves the utilization rate of frequency spectrum and the randomness of frequency hopping, and comprises the following steps: (1) framing by a digitized information source; (2) message driving and 2QFSK modulation; (3) taking IFFT for the modulated bits, adding cyclic prefix, and performing parallel-serial conversion; (4) the information source information is sent after the step 1-3 and reaches a receiving end through a channel; (5) performing serial-parallel conversion, removing cyclic prefix, and performing FFT operation; (6) and demodulating the driving bit according to a pair of sub-channels where the waveform is located. The frequency hopping based on 2QFSK modulation and IFFT/FFT provided by the invention is combined with the message driven frequency hopping technology, so that the frequency spectrum efficiency is obviously improved compared with the traditional frequency hopping technology, and the invention has a simpler demodulation method and certain anti-noise performance improvement compared with the message driven frequency hopping technology.)

1. A message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation is characterized by comprising the following steps:

(1) framing by a digitized information source, m ═ m per frame₁+m₂Bit information bits; wherein the front m₁Bits as message-driven drive bits, m₂Bits as regular bits, generating m₂2QFSK waveforms;

(2) message driving and 2QFSK modulation;

(3) taking IFFT for the modulated bits, adding cyclic prefix, and performing parallel-serial conversion;

(4) the information source information is sent after the step 1-3 and reaches a receiving end through a channel;

(5) performing serial-parallel conversion, removing cyclic prefix, and performing FFT operation;

(6) and demodulating a driving bit according to a pair of sub-channels where the waveform is positioned, and demodulating a conventional bit according to whether the waveform represents a sub-channel of '1' or a sub-channel of '0' in the pair of sub-channels.

2. The method according to claim 1, wherein the message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation (bpsk) is specifically expressed as follows, wherein the message-driven frequency hopping communication method in step (2) is based on 2QFSK modulation:

information is expressed as m₁+m₂Framing, wherein the first m₁The bit information is called as a driving bit, the whole channel is divided into N sub-channels, N is an even number, and the driving bit determines the frequency point of frequency hopping; rear m₂The bit information is called conventional bits, and one sub-channel is selected from N sub-channels to transmit information according to the values of the driving bits and the conventional bits by adopting a 2QFSK modulation mode.

3. The method according to claim 1, wherein the message-driven and 2QFSK demodulation in step (6) is specifically expressed as:

FFT is carried out on the received waveform, one path with the largest energy is selected, the driving bit and the carried 1-bit conventional bit are demodulated according to the path, and the process m is repeated₂All information of the whole frame can be demodulated.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation, which improves the utilization rate of frequency spectrum and the randomness of frequency hopping.

Background

In order to apply the message-driven technique to the frequency hopping communication system based on the IFFT/FFT structure, a new mapping method, Quadrature Frequency Shift Keying (QFSK), is proposed on the basis of the existing binary frequency Shift Keying (2 FSK). So-called quadrature frequency shift keying is to divide the entire available frequency band into N subchannels, which are overlapped with each other by 50%, and transmit a waveform representing "0" to the first half of the subchannels and a waveform representing "1" to the second half. Of all the sub-channels, the ith sub-channel and the (i + N/2) th sub-channel are called a pair of sub-channels, where i < N/2. The total subchannels may be divided into N/2 pairs of subchannels. During modulation, a pair of sub-channels is selected according to the value of the driving bit, and then whether the sub-channel representing 0 or the sub-channel representing 1 is used for transmitting the waveform in the pair of sub-channels is selected according to the value of the conventional bit. After the corresponding sub-channel is selected, N "0" or "1" is used to represent the state of whether N sub-channels are selected, where "0" represents that the sub-channel is not selected, and "1" represents that the sub-channel is selected. For binary quadrature frequency shift keying, only one of the N subchannels is selected. And then the N0 or 1 are subjected to IFFT to obtain the modulated waveform. The orthogonal frequency shift keying and the frequency shift keying mainly have two differences, namely, the modulated waveforms are different, the application occasions are different, the FSK can be widely applied to various communication systems, and the QFSK is mainly applied to a communication system based on an IFFT/FFT structure.

The existing FI communication technology is to combine the IFFT/FFT technology with the frequency hopping technology, generate a frequency hopping pattern by a frequency hopping sequence, control and select a subcarrier to transmit data, set other subcarriers as 0, map and modulate an information source bit first, then transmit data through serial-to-parallel conversion, IFFT operation and parallel-to-serial conversion, reach a receiving end through a channel, determine the subcarrier of the transmission data according to the frequency hopping pattern at the receiving end, and output the data after serial-to-parallel conversion, FFT, parallel-to-serial conversion and inverse mapping. The prior art has the disadvantages that the frequency spectrum utilization rate is not high and the frequency spectrum efficiency is low because only part of subcarriers transmit information, and under the condition that the frequency spectrum demand of the current communication system is tense, the frequency spectrum efficiency is increased on the basis of the prior art, which is very important, and the method has a great development prospect in the future communication field.

The existing Message Driven Frequency Hopping (MDFH) technology uses the message to replace the frequency hopping pattern in the traditional frequency hopping system, the message is used for controlling the frequency point of frequency hopping, and the receiving end compares the energy of the full frequency band, so that the message carried by the frequency hopping point can be demodulated. Compared with the traditional frequency hopping system, the message-driven frequency hopping technology can save a large amount of hardware resources consumed synchronously, and can improve the frequency spectrum efficiency. But results in a large number of errors when the comparison energy at the receiving end is wrong.

Compared with the traditional multi-carrier communication system of MPSK/QAM modulation, the multi-carrier communication system has good resistance effect on Doppler frequency shift because 2QFSK modulation and an IFFT/FFT framework are adopted for modulation and demodulation.

Disclosure of Invention

The invention aims to provide a message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation.

The purpose of the invention is realized as follows:

a message-driven frequency hopping communication method based on binary orthogonal frequency shift keying modulation comprises the following steps:

(1) framing by a digitized information source, m ═ m per frame₁+m₂Bit information bits; wherein the front m₁Bits as message-driven drive bits, m₂Bits as regular bits, generating m₂2QFSK waveforms;

(2) message driving and 2QFSK modulation;

(3) taking IFFT for the modulated bits, adding cyclic prefix, and performing parallel-serial conversion;

(4) the information source information is sent after the step 1-3 and reaches a receiving end through a channel;

(5) performing serial-parallel conversion, removing cyclic prefix, and performing FFT operation;

(6) and demodulating a driving bit according to a pair of sub-channels where the waveform is positioned, and demodulating a conventional bit according to whether the waveform represents a sub-channel of '1' or a sub-channel of '0' in the pair of sub-channels.

The message driving and 2QFSK modulation in step (2) of the method can be specifically expressed as follows:

information is expressed as m₁+m₂Framing, wherein the first m₁The bit information is called as a driving bit, the whole channel is divided into N sub-channels, N is an even number, and the driving bit determines the frequency point of frequency hopping; rear m₂The bit information is called conventional bits, and one sub-channel is selected from N sub-channels to transmit information according to the values of the driving bits and the conventional bits by adopting a 2QFSK modulation mode.

The message driving and 2QFSK demodulation in step (6) of the method can be specifically expressed as follows:

FFT is carried out on the received waveform, one path with the largest energy is selected, the driving bit and the carried 1-bit conventional bit are demodulated according to the path, and the process m is repeated₂All information of the whole frame can be demodulated.

The invention has the beneficial effects that:

the frequency hopping based on 2QFSK modulation and IFFT/FFT provided by the invention is combined with the message driven frequency hopping technology, so that the frequency spectrum efficiency is obviously improved compared with the traditional frequency hopping technology, and the invention has a simpler demodulation method and certain anti-noise performance improvement compared with the message driven frequency hopping technology.

Drawings

FIG. 1 is a block diagram of an IFFT/FFT-based frequency hopping (FI) communication system;

FIG. 2 is a block diagram of a message driven frequency hopping communications system based on binary quadrature frequency shift keying modulation;

FIG. 3 is a diagram of message driven frequency hopping communication system subchannel partitioning based on binary quadrature frequency shift keying modulation;

FIG. 4 is a schematic diagram of a message driven frequency hopping communication system modulation and demodulation mapping based on binary orthogonal frequency shift keying modulation;

FIG. 5 is a diagram of subchannel hopping;

FIG. 6 is a graph of the error rates of three mapping schemes of 2QFSK, BPSK and QPSK;

FIG. 7 is a graph of the error rates of three mapping schemes of 2QFSK, BPSK and QPSK;

fig. 8 is a graph comparing transmission efficiency of two frequency hopping systems.

Detailed Description

The present invention will be described more fully and clearly in the following description, taken together with the accompanying drawings, wherein it is to be understood that the above description of the preferred embodiments of the invention is illustrative, and not restrictive.

FIG. 1 is a block diagram of an IFFT/FFT-based frequency hopping (FI) communication system;

FIG. 2 is a block diagram of a message driven frequency hopping communications system based on binary quadrature frequency shift keying modulation;

FIG. 3 is a diagram of message driven frequency hopping communication system subchannel partitioning based on binary quadrature frequency shift keying modulation;

FIG. 4 is a schematic diagram of a message driven frequency hopping communication system modulation and demodulation mapping based on binary orthogonal frequency shift keying modulation;

fig. 5 is a schematic diagram illustrating subchannel hopping as exemplified by N8 and m2 being 3;

FIG. 6 is a comparison of error rates of three mapping schemes, 2QFSK, BPSK and QPSK, without Doppler;

FIG. 7 is a comparison of error rates of three mapping types, 2QFSK, BPSK and QPSK, in the case of Doppler shift of 100 Hz;

fig. 8 is a comparison of unit time spent by the message-driven frequency hopping communication system based on 2QFSK modulation and IFFT/FFT framework and the ordinary 2QFSK frequency hopping communication system for transmitting the same number of bits when the number of symbols transmitted per hop is different under the condition of transmitting 2 waveforms per unit time at 128 frequency points, 64 hop points, and unit time.

Specifically, fig. 1 is a block diagram of an FI communication system, fig. 2 is a block diagram of a message-driven frequency hopping communication system based on binary quadrature frequency shift keying modulation, and a transmitting end mainly includes the following steps:

step 1: parameters of the system are determined. Including the total number of subchannels N and the number of regular bits m₂. Framing by digital source, each frame having m ═ m₁+m₂Bit information bits according to the formula m₁＝log₂And N, calculating the number of the drive bits. Fig. 3 shows a subchannel division rule, which divides the entire frequency band into N subchannels, with 50% overlap between each subchannel. Wherein the first N/2 sub-channels are used to transmit a "0", and wherein the last N/2 sub-channels are used to transmit a "1".

Step 2: message driving and 2QFSK modulation; as shown in fig. 4, a pair of sub-channels is first selected according to the driving bit, and then a sub-channel is selected from the pair of sub-channels according to the value of the regular bit to transmit information. The selected sub-channel is denoted by "1" and the other off sub-channels are denoted by "0".

And step 3: and performing N-point IFFT on N bits of information representing the subchannel state to obtain a time domain waveform.

And 4, step 4: and adding a cyclic prefix to the modulated waveform, performing parallel-serial conversion, and transmitting the modulated waveform to a channel through up-conversion.

And the information source selects different subchannel combinations according to different driving bits to realize frequency hopping. With N being 8, m₂For example, there are 8 subcarrier activation combinations, that is, there are 8 frequency hops, and fig. 5 is a simple frequency hopping diagram of N-8 and k-3. The carried two frames of information are 010100,111101, the first 3 bits of each frame represent the information of the carrier, and the last 3 bits represent the carried conventional bit information.

The system receiving end mainly comprises the following steps:

and 5: performing down-conversion, serial-to-parallel conversion, removing cyclic prefix, and performing N-point FFT operation;

step 6: all the drive bits and 1 bit conventional bits can be demodulated once according to the frequency point where the maximum energy is located, and the step 5m is repeated₂Then the information of the whole frame can be demodulated. Can simultaneously pair m₂The secondary demodulation result is subjected to soft decision, and some bit errors can be corrected to a certain extent. After one frame of bits is demodulated, demodulation information is output, and the whole communication process is completed.

The present invention generally relates to the field of wireless communication technologies, and in particular, to a binary quadrature frequency shift keying (2QFSK) technology, a Message Driven Frequency Hopping (MDFH) technology, and a frequency Hopping (FH based on IFFT/FFT) communication technology.

The invention discloses a message-driven frequency hopping communication system based on binary orthogonal frequency shift keying modulation, and belongs to the technical field of wireless communication. A modulation of orthogonal frequency shift keying (QFSK) is provided, and is combined with a frequency hopping (Fbaseband on IFFT/FFT, FI) communication technology based on IFFT/FFT, and information is modulated on a waveform and a frequency point respectively in a message driving mode. Compared with the common frequency hopping, the method has higher spectral efficiency and better system performance; compared with index modulation frequency hopping based on an IFFT/FFT framework, the method has the advantages of simpler receiving end structure, simpler demodulation method and better anti-fading performance. Compared with a multi-carrier communication system based on MPSK/QAM modulation, the multi-carrier communication system has better Doppler frequency shift resistance.

The invention provides a message-driven frequency hopping communication system based on 2QFSK modulation and IFFT/FFT framework aiming at the problems of low frequency spectrum efficiency of the existing FI communication technology and higher error code of the existing message-driven frequency hopping (MDFH) technology during demodulation, adds the message-driven frequency hopping (MDFH) technology on the basis of the existing FI communication technology to improve the frequency spectrum utilization rate and the randomness of frequency hopping, and simultaneously adopts the 2QFSK modulation to improve the anti-noise performance to a certain extent.

The technical scheme of the invention is as follows:

2QFSK modulation and message driving technology are introduced to a system originating terminal to combine with an FI communication technology, so that frequency hopping is realized and spectrum efficiency is improved. Dividing information bits into drive bits and conventional bits, and determining a pair of sub-channel transmission information through the drive bits; the method specifically determines which sub-channel in a pair of sub-channels transmits information through conventional bits, and achieves the purpose of realizing the frequency hopping function by combining the information driven frequency hopping and 2QFSK modulation technology with the FI communication technology.

The whole system link of the invention is shown in fig. 2 and comprises a digital source, a drive bit mapping, 2QFSK modulation, a channel, drive bit demodulation and conventional bit demodulation.

A message-driven frequency hopping communication system based on 2QFSK comprises the following steps:

step 1: framing by a digitized information source, m ═ m per frame₁+m₂Bit information bits; wherein the front m₁Bits as message-driven drive bits, m₂Bits as regular bits, generating m₂2QFSK waveforms;

step 2: message driving and 2QFSK modulation; if N subcarriers are provided and two subcarriers are activated for data transmission, then m₁＝log₂(N/2) according to m₁The value of the bit-driving bit selects a certain pair of subcarriers β i, k and β i, k + N/2 to transmit the waveform, wherein the subcarriers β i, k are used to transmit the information "0" in the regular bit and the subcarriers β i, k + N/2 are used to transmit the information "1" in the regular bit. The drive bit has m₂Bits, thus co-propagating m on the pair of sub-channels₂A waveform;

and step 3: taking the modulated bits representing the on-off states of N subcarriers as N-point IFFT, adding cyclic prefix, and performing parallel-serial conversion; and the information source selects hopping frequency points according to the driving bits to realize frequency hopping. Then, information '0' and information '1' are transmitted on different sub-channels through 2QFSK modulation;

and 4, step 4: the information source information is sent after the step 1-3 and reaches a receiving end through a channel;

and 5: performing serial-parallel conversion, removing a cyclic prefix, and performing N-point FFT operation;

step 6: and demodulating a driving bit according to a pair of sub-channels where the waveform is positioned, and demodulating a conventional bit according to whether the waveform represents a sub-channel of '1' or a sub-channel of '0' in the pair of sub-channels. The demodulated bits are output in combination with the drive bits and the regular bits.

The message driving and 2QFSK modulation in step 2 may be specifically expressed as:

information is expressed as m₁+m₂Framing, wherein the first m₁The bit information is called as a driving bit, the whole channel is divided into N sub-channels (N is an even number), and the driving bit determines a frequency point of frequency hopping, namely the specific pair of sub-channels in the N sub-channels is used for transmitting information; rear m₂Bit informationCalled as regular bits, adopts a 2QFSK modulation mode to select one sub-channel from N sub-channels to transmit information according to the values of the drive bits and the regular bits. The subchannel information is mapped into N bits, and the N bits of information are subjected to IFFT to obtain a time domain waveform, so that the whole modulation process is completed.

The message driving and 2QFSK demodulation in step 6 can be specifically expressed as:

FFT is carried out on the received waveform, one path with the largest energy is selected, the driving bit and the carried 1-bit conventional bit are demodulated according to the path, and the process m is repeated₂All information of the whole frame can be demodulated.

In summary, the present invention combines the 2QFSK modulation technique with the IFFT/FFT framework and message-driven technique. A pair of subcarriers in an IFFT/FFT frame is selected through message driving, frequency hopping is realized and a modulation waveform is transmitted by adopting a 2QFSK modulation mode, and the method comprises the following steps:

step 1: framing by a digitized information source, m ═ m per frame₁+m₂Bit information bits; wherein the front m₁Bits as message-driven drive bits, m₂Bits as regular bits, generating m₂2QFSK waveforms;

step 2: message driving and 2FSK modulation; if N subcarriers are provided and two subcarriers are activated for data transmission, then m₁＝log₂(N/2) according to m₁The value of the bit-driving bit selects a certain pair of subcarriers β i, k and β i, k + N/2 to transmit the waveform, wherein the subcarriers β i, k are used to transmit the information "0" in the regular bit and the subcarriers β i, k + N/2 are used to transmit the information "1" in the regular bit. The drive bit has m₂Bits, thus co-propagating m on the pair of sub-channels₂A waveform;

and step 3: taking the modulated bits representing the on-off states of N subcarriers as N-point IFFT, adding cyclic prefix, and performing parallel-serial conversion; and the information source selects hopping frequency points according to the driving bits to realize frequency hopping. Then, information '0' and information '1' are transmitted on different sub-channels through 2QFSK modulation;

and 4, step 4: the information source information is sent after the step 1-3 and reaches a receiving end through a channel;

and 5: performing serial-parallel conversion, removing a cyclic prefix, and performing N-point FFT operation;

step 6: and demodulating a driving bit according to a pair of sub-channels where the waveform is positioned, and demodulating a conventional bit according to whether the waveform represents a sub-channel of '1' or a sub-channel of '0' in the pair of sub-channels. The demodulated bits are output in combination with the drive bits and the regular bits.

The message driving and 2QFSK modulation in step 2 may be specifically expressed as:

information is expressed as m₁+m₂Framing, wherein the first m₁The bit information is called as a driving bit, the whole channel is divided into N sub-channels (N is an even number), and the driving bit determines a frequency point of frequency hopping, namely the specific pair of sub-channels in the N sub-channels is used for transmitting information; rear m₂The bit information is called conventional bits, and one sub-channel is selected from N sub-channels to transmit information according to the values of the driving bits and the conventional bits by adopting a 2QFSK modulation mode. The subchannel information is mapped into N bits, and the N bits of information are subjected to IFFT to obtain a time domain waveform, so that the whole modulation process is completed.

The message driving and 2QFSK demodulation in step 6 may be specifically expressed as:

FFT is carried out on the received waveform, one path with the largest energy is selected, the driving bit and the carried 1-bit conventional bit are demodulated according to the path, and the process m is repeated₂All information of the whole frame can be demodulated.