TW202347994A - Fmcw radar-communication method and system - Google Patents

Abstract

A frequency modulated continuous wave (FMCW) radar-communication method and system are provided, the method or system is applied to communicate between a first object and a second object, wherein the first object has a signal transmission device and a radar receiving device. The method includes a signal transmission module of the signal transmission device to perform: dividing a transmitting signal which contains a FMCW chirp signal into D sub-chirps; setting each of the sub-chirps to carry a frequency index modulated (FIM) symbol; deciding a special resource block (RB) for being occupied by the sub-chirp according to the FIM symbol; and transmitting the sub-chirp using the special resource block for enhancing a system transmission rate of the transmitting signal.

Description

Frequency modulated continuous wave radar communication method and system

The present invention is a frequency modulated continuous wave radar communication method and system, particularly a frequency modulated continuous wave radar communication method and system that cuts a signal to be transmitted containing a FMCW chirp signal into D sub-signals.

In recent years, with the rise of self-driving cars and the Internet of Things industry, radar communication (Rad-Com) systems that combine radar sensing and communication functions in self-driving cars have attracted much attention. Among them, based on linear frequency modulation continuous wave (Frequency Modulated Continuous Wave, FMCW) system has the characteristics of easy implementation and low complexity. Compared with other systems (such as Orthogonal Frequency Division Multiplexing (OFDM) system), it occupies the leading position in practice. However, because the traditional linear frequency modulation continuous wave radar communication system is limited by the choice of waveform, the system has a low communication transmission rate, so its communication transmission capabilities do need to be strengthened. .

For frequency hopping (Frequency Hopping)-assisted radar communication systems, the conventional technology proposes to use frequency hopping waveforms to implement radar and communication functions. Although it can naturally avoid interference through the frequency hopping mechanism, its radar and communication performance will be affected. Limited to waveform selection, usage bandwidth and number of antennas. For FMCW-based For radar communication (FMCW-based Rad-Com) systems, there is a technology proposed to increase the degree of freedom of transmitting symbols by selecting the signal carrier frequency and antenna. Although it can take into account the performance of both radar and communication and improve the system transmission rate, its Large bandwidth and huge antenna array resources are required to significantly improve the transmission rate. In addition, its technology does not explore the impact of multi-user interference on its system.

To consider the mutual interference between multiple FMCW-based Rad-Com systems, some technologies have proposed a carrier sense multiple access (CSMA) protocol for the communication end. Although the radar can be adjusted The transmission time is used to improve the system's anti-interference capability, but it is not a physical layer design. When traditional radar performs target detection, it uses two-dimensional Fourier transform (2D-FFT) on the received signal to obtain the range Doppler map (R-D map), and then uses the R-D map to estimate the target distance, speed and angle information. Once it changes Due to the characteristics of the received signal, it will not be possible to directly use 2D-FFT to obtain the R-D map.

For this reason, how to solve the problem that the performance of radar and communication is limited by waveform selection, usage bandwidth and number of antennas in order to increase the communication transmission rate? In view of the deficiencies in the conventional technology, the present application has been carefully tested With research and perseverance, the present invention was finally conceived, which overcomes the shortcomings of the prior art by proposing to cut one of the chirp signals containing FMCW to be transmitted into D sub-signals. The following is a brief description of the present invention.

The present invention discloses a frequency modulated continuous wave (FMCW) radar communication method for communication between a first object and a second object, wherein the first object has a signal transmission device and a radar receiving device, including the signal transmission device The signal transmission module executes: cutting the signal to be transmitted containing the chirp signal of FM continuous wave into D sub-signals; making each sub-signal carry a frequency index modulation symbol (FIM symbol); according to the FIM symbol The code determines the specific resource block (RB) occupied when transmitting the sub-signal; and uses the specific resource block to transmit the sub-signal in order to increase the system transmission rate of the signal to be transmitted.

According to other applicable viewpoints, the present invention also discloses a communication system that performs the above communication method, including the signal transmission device, the radar receiving device and the signal receiving device. The signal transmitting device is used to transmit the D sub-signal to the second object; the radar receiving device is used to receive the reflected signal of the transmitted D sub-signal reflected from the second object in order to detect the The distance between the first object and the second object, the speed of the second object, and the incident angle between the forward direction of the reflected signal and the forward direction of the first object; and a signal receiving device for receiving and interpreting The D sub-signal is adjusted to analyze the D sub-signal of the signal transmitting device.

The present invention can also be a communication system that performs the above communication method, including the above communication system, wherein the sub-signal is a model signal, and the system is a transmitter and multiple receiver system and is used for 77GHz vehicle high-resolution rate radar frequency band.

The invention is a radar signal transmission and reception method, which includes cutting a signal to be transmitted into a plurality of sub-signals; providing a plurality of transmission symbols; and causing a specific sub-signal in the plurality of sub-signals to carry one of the plurality of transmission symbols to determine the transmission This specific sub-signal occupies a specific resource block to achieve the purpose of increasing the system transmission rate.

10:Radar communication system

11:First object

12:Second object

121:Signal receiving device

122: Communication signal demodulation module

123: Beamforming algorithm

124: Transmission code estimation result

13:Signal transmission device

131: User scheduling algorithm

14: Radar receiving device

15:Signal transmission module

151:Channel

16:Antenna module

17: Radar target detection

18: Radar parameter estimation module

19: Target distance, speed, incident angle

S21~24: Steps executed by the signal transmission module 15

S31~33: Method of sending FIM code and appending APM code

The first figure: is a schematic diagram of the transmission architecture of the FMCW radar communication system and method according to the preferred embodiment of the present invention;

The second picture: is a flow diagram of the communication method in the first picture;

The third picture: is a schematic diagram of the process of determining the FIM code and appending the APM code in the second picture;

The fourth figure is a schematic flowchart of the first method of estimating the interference correlation matrix when multiple users use the present invention;

Figure 5: is a schematic flow chart of the second method of estimating the interference correlation matrix when multiple users use the present invention;

The sixth picture: is a design table of simulation parameters that can be used when implementing the communication method in the first picture;

Figure 7: is an evaluation coordinate chart of the detection rate (Detection Rate) versus the False Alarm Rate (False Alarm Rate) of the traditional FMCW and the radar receiving device of the present invention;

Figure 8: A plot of the bit error rate versus the number of groups using the reference signal to estimate the interference-noise correlation matrix; and

Figure 9: This is a graph of the bit error rate versus the number of groups using the radar idle time to estimate the interference noise correlation matrix.

In order to improve the communication transmission rate of the traditional linear frequency modulated continuous wave radar communication system, information embedding (IM) technology can be introduced to enhance it. The present invention proposes a new type of radar communication system. The Rad-Com system model and the radar target sensing and communication signal demodulation solutions corresponding to this model enable FMCW, radar and communication systems to become an integrated architecture, taking into account multiple User interference will reduce system efficiency. At the same time, an interference response mechanism is proposed to enhance the practicality of the system. The system model and design are based on linear frequency modulation continuous wave radar communication based on frequency hopping.

Please refer to the first figure, which shows the frequency modulated continuous wave (FMCW) radar communication system 10 and method of the present invention (i.e., the first core content: the linear frequency modulated continuous wave radar communication system signal model based on frequency hopping), which is used in Communication between the first object 11 (for example: a user's self-driving car, a communication device for the car, an on-board unit (OBU), etc.) and the second object 12 (for example: a self-driving car of another user) One embodiment. The first object 11 has a signal transmitting device 13 (i.e., the signal transmitting end) and a radar receiving device 14 (i.e., the radar receiving end). The purpose of communication is to demodulate the code and obtain the transmission information of the transmitting end. This system can consider using a one-transmit-multiple-receive system (the first object 11 or the second object 12 is each configured with multiple antennas, one antenna is used to send signals, and multiple antennas are used to receive signals), including the The signal transmission module 15 in the signal transmission device 13 performs what is shown in the second figure: cutting one of the signals to be transmitted containing a traditional frequency modulated continuous wave (FMCW) chirp signal into D sub-signals (sub- chirp) S21, each sub-signal occupies 1/D of the bandwidth (i.e. sub-signal bandwidth) and time length of the original FMCW signal. The model of the present invention will all start from sub-signals, with FMCW as a reference model.

Each sub-signal carries a frequency index modulation symbol (FIM symbol) S22, which has a one-to-one correspondence with the sub-signal when transmitting data; the specific resource area occupied when transmitting the sub-signal is determined based on the FIM symbol block (Resource Block, RB) S23 (that is, a FIM symbol will determine the unique sub-signal transmission frequency band and achieve the purpose of frequency hopping); and use the specific resource block to transmit the sub-signal (i.e. model signal) in order to achieve improvement The system transmission rate of the signal to be transmitted is S24.

Relative to the total signal bandwidth TB used by the original FMCW, each sub-signal in the cut D sub-signals can be reasonably assumed to have a bandwidth of B _o = TB /D. In addition, it is assumed that the total system bandwidth of the radar communication system in this embodiment can include W resource blocks, and the total system bandwidth is a value B given by the system. After the system determines the total bandwidth B , it will Cut the frequency band according to W, so that there are W resource blocks in the total bandwidth, and the bandwidth of each resource block is B / W (the bandwidth of this resource block is usually set by the system. In some implementations In this example, a system only transmits one sub-signal at one point in time. Each sub-signal with a bandwidth B can be transmitted on any of _the W resource blocks according to a transmission rule to achieve the purpose of frequency hopping. , and the bandwidth B /W occupied by each resource block is also equal to or approximately equal to B _o . In an embodiment in which the first object 11 or the second object 12 can occupy the W resource blocks, W can Set equal to D to obtain a better transmission rate, but not limited to this. How to set the bandwidth occupied by each resource block, how to cut each sub-signal and the bandwidth of each sub-signal, etc., It can be preset according to the communication protocol of the system, or set according to the agreement between communication objects (or users).

In an embodiment in which the first object 11 or the second object 12 can occupy the W resource blocks, although the number of W may not be equal to the number of D, there will be two situations: first, when W is less than D, it will cause the number of resource blocks available for frequency hopping to become smaller, that is, there will be fewer FIM options, and the communication rate will be lower. can be reduced; secondly, when W is greater than D, the radar signal processing resources will be reduced, which will reduce the radar detection effect. The number of D and W is related to the waveform of the sub-signal; so in a better situation, you can choose to make W The number is equal to the number of D to measure the performance of radar and communication. This assumption is set by the system from the beginning. In some examples of this disclosure, similar assumptions are also made, that is, the number of cut sub-signals used by any object (or user) will be the same as that assigned to the object (or user). users) have the same number of resource blocks (that is, both are D), but this disclosure is not intended to be limited to this.

In one embodiment of the present invention, the chirp signal contained in the sub-signal can be expressed as follows:

其中f _c 為起始頻率，B _o 及T _o 分別為子訊號使用頻寬及時間長度。

Among them, f _c is the starting frequency, B _o and T _o are the sub-signal usage bandwidth and time length respectively.

If in the aforementioned embodiments shown in the first and second figures, D is the nth power of 2, n is a positive integer; the FIM code is a transmission FIM code, and the degree of freedom of the FIM code can be corresponding The setting is D. For example, when D=2, the degree of freedom of the FIM symbol can be 2, and correspond to a pattern in which 1 bit is combined into 1 character, that is, it can correspond to 2 characters such as 0 and 1. For another example, when D=4, the degree of freedom of the FIM symbol is 4, and it corresponds to a pattern in which 2 bits are combined into 1 character, which can correspond to 4 characters such as 00, 01, 10, and 11. In the two embodiments described below, it is assumed that the degree of freedom of the FIM symbol and the number of sub-signals are equal, both being D (2 or 4). However, in practice, it is not limited to this. For example, the degree of freedom of a user's FIM code is E, and E may not be equal to D. Especially when resource blocks are grouped, the degree of freedom of each user will be less than D. . The communication method further includes a determining character array as shown in the third figure. Column/word string, the array can also be configured to include D sub-arrays/characters accordingly, and each sub-array includes n bits S31 and corresponds to a transmission FIM code. The D sub-arrays/characters are read sequentially to determine the transmission FIM code assigned to the sub-signal. In some embodiments, the character array corresponding to the transmitted FIM code can also be implemented as the user arbitrarily determines the information they want to transmit (either images or audio can be encoded into strings). The transmission FIM code refers to the code used to carry the transmission information in order to determine the specific resource block S32 for transmitting each of the D sub-signals.

After fixing the cutting number, the number of characters corresponding to the FIM code can be determined. A sub-signal will be cut into equal parts to determine how many bits need to be combined. Therefore, how many bits the FIM code should correspond to will be determined according to the cutting. Change with the number D. FIM is determined by these characters, and the FIM symbol is equivalent to determining/designating/representing a fixed number of frequency bands (i.e., frequency band numbers), because the number of the resource block used to transmit sub-signals will be determined by characters. It is determined by all the characters in the element array. For example: when the signal to be transmitted is cut into 2 equal parts (D=2, n=1), it is assumed that the character array determined by the user happens to be each corresponding FIM character. A special case where the characters of the code are all different and arranged from small to large. The character array of 2 characters can be {0,1}, and the FIM code corresponding to the first sub-signal is the first character of the array. Subarray/bit 0 (in this case, one bit is exactly equal to one character), and because the first bit of the array is 0, the FIM code corresponds to the frequency band number, that is, it is used to determine the One sub-signal is transmitted on the frequency band of the resource block (band number 1) represented by this bit, and the second sub-signal will be transmitted on this bit because the second bit of the array is 1. The resource block corresponding to element 1 (band number is 2). Under this rule, if two sub-signals correspond to the same frequency band, Then the characters of the FIM code they imply are the same, and in applications where the characters of the FIM code are used to carry passenger information, the transmission rate can also be improved.

When the signal to be transmitted is cut into 4 equal parts (D=4, n=2), assuming that a detection frame has 1 chirp (ie M=1), when the character array generated by the user happens to be When the characters of the FIM code corresponding to each sub-signal are different and are arranged from small to large, that is, the character array of four strings is {00,01,10,11} (here in two bits element as a string/character. Of course, depending on practical conditions, there must be the possibility of other character arrays, such as {00,00,00,00} or {01,10,00,11}, etc.), then The subarrays/strings 00, 01, 10, and 11 in the character array correspond to the resource blocks of frequency band numbers 1, 2, 3, and 4 respectively (in this case, two bits are used to represent a resource area one character of the block).

At this time, the FIM code of the first sub-signal corresponds to the first two bits 00 of the array, which determines the resource block of frequency band number 1. By analogy, the character array will determine that four sub-signals occupy resource blocks with frequency band numbers 1, 2, 3, and 4 respectively. If the cutting equal number is 8 (D=8, n=3), then 3 bits are combined to form a FIM code (in this case, three bits are used to represent one character); if it is cut into more In equal parts, there will be more bits to represent one character (for example: when D=16, n=4, 4 bits will be used to represent 1 character). The number of sub-signals in the detection frame is D*M (M is the number of chirps). The FIM code carried by one sub-signal can carry one character = log2 (D) bits of information. Therefore, in one In the detection frame, the maximum amount of information that can be transmitted through the FIM code is D*M*log2 (D) bits.

In addition, the signal transmission module 15 can further execute the The sub-signal is additionally transmitted with an amplitude phase modulation symbol (APM symbol, i.e. the additional modulation symbol on the sub-signal, and the FIM symbol is entrained on the sub-signal) to increase the system transmission capacity S33 (i.e. when using When APM code is used, the transmission rate of the system will increase). APM code also refers to a code used to carry transmission information. The final transmission base signal can be expressed as:

由式(2)中可以看出子訊號中隱含了FIM及APM符碼，其中a ^F1M及a ^APM分別為一個子訊號所攜帶之頻率索引及振幅相位調變符碼，P為訊號功率。本實施例提出模型就是利用切割的方式將原FMCW訊號切成若干個子訊號，再藉由FIM符碼進行跳頻或攜帶資訊。當然APM符碼也是一種可攜帶資訊的符碼，可以BPSK、QPSK、16-QAM等類似技術來實現。系統會先決定APM符碼要採用哪種調變形式來傳送，再根據該APM符碼所對應的字元來調變(例如，如果是BPSK就是一字元，QPSK是兩字元等)。根據此模型，傳輸速率R可計算如下：

It can be seen from equation (2) that the FIM and APM symbols are implicit in the sub-signal, where a ^F1M and a ^APM are the frequency index and amplitude phase modulation symbol carried by a sub-signal respectively, and P is the signal power. The model proposed in this embodiment is to use cutting method to cut the original FMCW signal into several sub-signals, and then use FIM symbols to perform frequency hopping or carry information. Of course, the APM code is also a code that can carry information and can be implemented by BPSK, QPSK, 16-QAM and other similar technologies. The system will first determine which modulation form the APM code should be used to transmit, and then modulate it according to the characters corresponding to the APM code (for example, if it is BPSK, it is one character, QPSK is two characters, etc.). According to this model, the transmission rate R can be calculated as follows:

R = (log ₂ ( D ) + log ₂ ( J ))/ T _o (bits/s), equation (3) where J is the constellation size of the amplitude phase modulation symbol (APM Constellation size). It can be seen from equation (3) that the transmission rate of this model is greatly improved compared to the FMCW+APM system (transmission rate: log2( J )/ DT _o bits/s). It is worth mentioning that D in the proposed model is a system design parameter, which will make a trade-off between hardware complexity and system transmission rate. However, since hardware complexity is difficult to evaluate, D is not discussed in this invention. design.

In the aforementioned embodiments, the communication method may further include a corresponding radar target detection technology (i.e., the second core content: based on the information It can be applied to the radar side under the signal model). Although this embodiment cannot directly use 2D-FFT to obtain the R-D map due to the change of the characteristics of the received signal. However, inspired by the concept of 2D-FFT, this technology uses the pre-calculated distance and The speed resolution combines the received signals at the maximum ratio to produce an R-D map. This is done by the antenna module 16 of the radar receiving device 14 receiving the reflected signals reflected from the second object 12 after each sub-signal is transmitted (ie, sensing the environment by "radar target detection 17"); and by the radar The radar parameter estimation module 18 of the device 14 performs calculation of the estimated range resolution and the estimated speed resolution based on the reflected signal.

The estimated distance resolution and the estimated speed resolution are then used to perform Maximum Ratio Combining (MRC) to generate an estimated distance map (R-D map); the estimated distance map is calculated Letou uses a Constant false alarm rate (CFAR) detector to estimate the distance between the first object 11 and the second object 12 and the speed of the second object 12, so that the distance and speed of the target can be restored; Assume The system bandwidth is B and the time length of the original FMCW signal is T. Then the calculated distance and speed resolution are:

其中，c為光速。根據估測之距離及速度解析度，利用最大比例組合所產生之R-D map可表示為：

Among them, c is the speed of light. According to the estimated distance and speed resolution, the RD map generated by the maximum ratio combination can be expressed as:

其中0

k

N _o -1；0

i

D-1；0

j

M-1；1

q

Q。式(5)中N _o 為子訊號於雷達端之取樣點數、M為一個偵測幀(detection frame)中原FMCW之chirp的個數、q是指第q根天線、Q為雷達接收端的天線個數 /總數、H為雷達接收訊號矩陣、

為第k個子訊號所攜帶之 FIM symbol、

為第k個子訊號所攜帶之APM symbol、

為估測之目標時間延遲、

為估測之目標都卜勒速度。

of which 0

k

N _o -1; 0

i

D -1;0

j

M -1;1

q

Q. In formula (5), N _o is the number of sampling points of the sub-signal at the radar end, M is the number of chirps of the original FMCW in a detection frame, q refers to the qth antenna, and Q is the antenna at the radar receiving end. Number/total number, H is the radar receiving signal matrix,

is the FIM symbol carried by the k- th sub-signal,

is the APM symbol carried by the k -th sub-signal,

is the estimated target time delay,

The target Doppler velocity for estimation.

)通過CFAR檢測器後會估計出目標(例如：第二物件12)之距離及速度；以及利用傳統的角度估計法估算該反射訊號的前進方向與第一物件11的前進方向之間的入射角(即估測第一目標入射角(Direction of arrival,DoA))，此時即將第二物件12區分為第一目標，資以藉由上述流程獲得目標距離、速度、入射角19。 Finally, the estimated RD map (i.e.

) will estimate the distance and speed of the target (for example: the second object 12) after passing through the CFAR detector; and use the traditional angle estimation method to estimate the incident angle between the forward direction of the reflected signal and the forward direction of the first object 11 (That is, estimating the first target incident angle (Direction of Arrival, DoA)). At this time, the second object 12 is classified as the first target, so that the target distance, speed, and incident angle 19 can be obtained through the above process.

In the aforementioned embodiments, the angle estimation method is Fourier transform or a subspace-based angle estimation method, and the subspace-based angle estimation method is multiple signal classification (MUltiple Slgnal Classification, MUSIC) or a rotation-invariant signal parameter estimation. (estimation of signal parameters via rotational invariance technique,ESPRIT).

In the foregoing embodiments, in order to accurately estimate the transmission symbols, the present invention can further cooperate with a corresponding communication signal demodulation technology/method (that is, the third core content, extracting the symbols), and the first method The symbol demodulation technology is continuous detection. The FIM symbol is estimated first, and then the APM symbol is estimated. At this time, the second object 12 has a signal receiving device 121 (i.e., the communication receiving end), and it is worth mentioning What is more, in order to calculate the energy of all resource blocks, the communication method further includes setting the sampling frequency (sampling rate) of the signal receiving device 121 to the system bandwidth (i.e., by the communication signal demodulation module 122 of the signal receiving device 121 B ); Receive the transmitted sub-signals according to the sampling frequency; use an energy detector to check and calculate the frequency band energy of each sub-signal in each resource block transmitted using the frequency band.

(即相當於，透過能量頻譜(spectrum)檢測以解析傳送端可能的FIM符碼訊號)，並表示如下式： Then take out the estimated resource block corresponding to the detected frequency band with the largest energy; then obtain the estimated FIM symbol based on the estimated resource block

(That is, equivalent to analyzing the possible FIM code signals at the transmitter through energy spectrum detection), and expressed as follows:

其中E(．)為能量計算函數。

Among them, E (.) is the energy calculation function.

後，再利用帶通濾波器(Band-pass filter,BPF)以降低該估測FIM符碼所對應之頻帶以外之其他頻帶的干擾，而濾出佔據該估測資源區塊頻段之過濾後接收訊號以降低其他頻帶之干擾；以及最後利用最大相似/似然(Maximum-Likelihood,ML)檢測器還原出該過濾後接收訊號中所具有之一估測APM符碼

(即ML用於檢測APM符碼)。該估測APM符碼

，可表示如下： Get estimated FIM code

Then, a band-pass filter (BPF) is used to reduce interference from other frequency bands other than the frequency band corresponding to the estimated FIM symbol, and filtered receivers occupying the frequency band of the estimated resource block are filtered out. signal to reduce interference from other frequency bands; and finally use a Maximum-Likelihood (ML) detector to restore an estimated APM symbol contained in the filtered received signal.

(That is, ML is used to detect APM symbols). The estimated APM code

, can be expressed as follows:

其中

為經過BPF及解chirp(de-chirp)處理之過濾後接收訊號、w為設計之波束權重、a(θ ₀)為在第二目標入射角(即，訊號接收裝置121之複數個天線所接收之接收訊號的入射角)為θ ₀之條件下，該訊號接收裝置121之複數個天線的指引向量(steering vector)、L為通道路徑損失、h為Rician通道係數、J為APM符碼集合，此時即將第一物件11區分為第二目標。本實施例藉此即可取得傳送符碼估計結果124。然而，連續估測會面臨錯誤傳播(Error propagation)的問題，原因是若FIM符碼偵測錯誤，則有非常大的機率APM符碼也會檢測錯誤。

in

is the filtered received signal processed by BPF and de-chirp (de-chirp), w is the designed beam weight, a ( θ ₀ ) is the signal received by multiple antennas of the signal receiving device 121 at the second target incident angle (i.e., Under the condition that the incident angle of the received signal) is θ ₀ , the steering vectors of the plurality of antennas of the signal receiving device 121, L is the channel path loss, h is the Rician channel coefficient, J is the APM symbol set, At this time, the first object 11 is classified as the second target. In this embodiment, the transmission code estimation result 124 can be obtained. However, continuous estimation faces the problem of error propagation because if the FIM code detects an error, there is a very high probability that the APM code will also detect an error.

及APM符碼

可表示式如下： In order to solve the problem of APM symbol detection errors caused by error propagation in the above embodiments, the present invention proposes a second symbol demodulation technology, which is joint detection. At this time, the second object 12 has a signal receiving device 121, and the communication method further includes the communication signal demodulation module 122 of the signal receiving device 121 receiving the transmitted D sub-signal (ie, through the transmitting end and the receiving end). channel between terminals and sub-signals affected by noise or interference signals); use the Maximum Similarity (ML) detector to check at one time a plurality of FIM symbols corresponding to a plurality of resource blocks that may transmit the sub-signal and the The sub-signal may carry a plurality of combinations of the APM codes, and obtain an estimated FIM code and an estimated APM code with the highest probability among the combinations of the plurality of FIM codes and the APM codes (i.e., using The maximum likelihood detector finds the most likely code combination among all possible code combinations). And using the FIM code estimated by joint detection

and APM code

It can be expressed as follows:

其中

為經過

所決定之BPF及de-chirp處理之過濾後接收訊號。雖然聯合偵測能解決連續偵測所擁有的錯誤傳播問題，但其所花費的複雜度也較高，因此兩者需要在效能及複雜度間做權衡。依此通訊訊號解調的方法，可於本實施例提出之模型架構下提供良好之通訊符碼的估計效果。

in

to pass by

The signal is received after filtering by the determined BPF and de-chirp processing. Although joint detection can solve the error propagation problem of continuous detection, it also requires higher complexity, so the two need to make a trade-off between performance and complexity. According to this communication signal demodulation method, a good estimation effect of communication symbols can be provided under the model framework proposed in this embodiment.

In the aforementioned embodiments, when multiple users use the system model proposed by the present invention at the same time, the radar receiving end of the first object 11 is fully aware of the codes used by its own transmitting end and can avoid interference through the frequency hopping mechanism. However, the communication receiving end of the second object 12 does not have any prior information about the codes used by the transmitting end, so it faces mutual interference from multiple users. If it is affected, it will lead to code demodulation errors. In response to this situation, in order to ensure smooth demodulation under multi-user conditions, in one embodiment of the present invention, the communication method may further include a multi-user interference avoidance and suppression technology/method/algorithm ( That is, the fourth core content is to solve the problem of interference and reduced system performance when multiple Rad-Com systems are used at the same time). The signal receiving device 121 combines the W resource blocks into a group of G frequency bands (which will be usable soon). The bandwidth is cut into G equal parts), so that each group of frequency bands has a specific number (for example: if the average allocation method is adopted, each group is allocated W/G) resource blocks, where the different G groups of frequency bands Group frequency bands are allocated to different users (i.e. Rad-Com systems).

Taking the embodiment where each object or user is allocated W/G resource blocks as an example, since different objects or users can only transmit signals in different frequency bands, it is assumed that each group transmits D sub-signals, and the G group of frequency bands will The D sub-signals can only be frequency-hopped within their respective W/G resource blocks, but have the advantage of multi-user interference avoidance. For example, in one embodiment, the first object 11 can be allocated to a frequency band with E resource blocks in the G group of frequency bands, and assuming E<D=W, and the first object 11 passes the FIM code The specific resource block occupied when transmitting the sub-signal is determined in the E resource blocks to achieve the effect of avoiding/reducing the impact of multi-user interference. However, this approach will be affected by the number of RBs in the frequency band. It is less than the original D number (assuming that the total resource block number Q of the original system is also equal to W) and sacrifices part of the degree of freedom of transmitting codes.

However, at this time, multiple objects or users can constitute multiple radar communication systems, and in the scenario of multiple communication systems, it does not rule out that the same resource block may be reused by different objects or users. For example, when the system differs When the number of users is greater than the number of frequency bands in the G group, some frequency bands may be allocated to different users. However, due to the limited bandwidth resources of the system, a specific user cannot use all the freedoms allocated to the specific user. Although the frequency is used to resist interference, interference in the same frequency band between different users will still occur/appear. At this time, in order to determine which frequency band and which time slot the user needs to transmit the signal, the user scheduling algorithm 131 in the signal transmission device 13 can be used to avoid the multi-user interference (that is, use scheduling to allocate resources /Different frequency bands are allocated to different users of the system according to specific rules to achieve interference avoidance/avoidance effects), which can effectively reduce mutual interference between users and thereby improve spectrum efficiency, greatly increasing the probability of successful code demodulation. In order to further perform interference rejection on co-channel users, the beamforming algorithm 123 in the signal receiving device can be used to suppress multi-user interference between different users using the same set of frequency bands (that is, using the resources of the multiple antennas to Realize beamforming) to suppress the energy of interference (that is, reduce the power of co-band interference). Based on the simulation results, it is also verified that the system we proposed has good radar detection and communication capabilities, and can also provide good anti-interference effects in multi-user scenarios.

In the aforementioned embodiments, the user scheduling algorithm 131 performs the following steps: allocates the G group of frequency bands to the different users; taking into account the performance and objectives of the energy detector used in the code demodulation technology (for example: The signal of object 12) is closely related to the Signal-to-interference-plus-noise ratio (SINR), so the goal of scheduling is to maximize the average SINR among different users, that is, it is hoped that through scheduling Find the most suitable allocation result (different users will have different SINRs depending on the allocation result); and because this optimization problem is a complex NP-hard problem (non-deterministic polynomial-time hardness, NP-hard) problem, this technology proposes to use a greedy scheduling algorithm to optimize and continuously allocate/provide different users with the choice of using each G group of frequency bands. The virtual program code (Pseudo Code) is represented as follows:

其中，虛擬程式碼中數量設定為U的系統(systems)係指與使用者相關之物件或用戶的統稱，該使用者系統可以是用戶的一輛自駕車、汽車用的通訊裝置、或車載單元(On Board Unit,OBU)等。

Among them, the systems (systems) whose number is set to U in the virtual program code refer to the objects or users related to the user. The user system can be a self-driving car of the user, a communication device for the car, or a vehicle-mounted unit. (On Board Unit, OBU) etc.

In the aforementioned embodiments, in order to further suppress co-band interference, the present invention also derives another interference suppression technology that utilizes antenna resources. The communication method further includes a user scheduling algorithm 131. After the scheduling results are determined/fixed, multiple antennas (i.e., multiple antennas) of the signal receiving device 121 and the beamforming algorithm 123 are used to perform/achieve beamforming with a maximum signal to interference plus noise ratio (MSINR) for further suppression. The power of multi-user interference between different users using the same set of frequency bands is intended to maintain the target signal gain and reduce the interference energy. Although beamforming itself has nothing to do with communication signal demodulation technology, it can assist the demodulation technology to do better. When the incident angle of the second transmitted target is known to be θ ₀ , the MSINR beam weight can be calculated as follows:

其中R _in 為干擾雜訊相關矩陣(interference-plus-noise correlation matrix)，是作為波束權重的輸入，需進行估計。

Among them, R _in is the interference-plus-noise correlation matrix, which is used as the input of the beam weight and needs to be estimated.

In order to accurately estimate R _in to achieve good beam detection effects, the present invention proposes two ways to estimate R _in . The first way is to use reference signals, or the second way is to collect data during radar idle time (idle time). Interference and noise data are used to estimate/estimate the interference-noise correlation matrix. The schematic flow chart of the first method is shown in the fourth figure. First, the reference signal is used to estimate R _in and the beam weight is calculated accordingly. The beam weight is then used to perform/implement the beam detection and forming step of the beam forming algorithm 123 . Step 1 in the fourth figure is preprocessing. After preprocessing, the i-th transmitted and filtered sub-signal (that is, the sub-signal after being affected by the channel between the transmitting end and the receiving end and the noise or interference signal , and then filtered and received signals after BPF and chirp processing, etc.), can be expressed as follows:

其中I為干擾個數、N _g 為子訊號於通訊端之取樣點數。接著利用該參考訊號之步驟係可藉由將經過通道151傳送後之該參考訊號所估計出之目標訊號(即參考訊號經過通道的訊號)從訊號接收裝置121接收之過濾後接收訊號y _i 中扣除，經過如 第四圖中所示的步驟二，以得到消除該目標訊號後之干擾及雜訊訊號r _i 可表示如下式：

Among them, I is the number of interference, _and Ng is the number of sampling points of the sub-signal at the communication end. The subsequent step of utilizing the reference signal is to obtain the target signal estimated by the reference signal transmitted through the channel 151 (ie, the signal through which the reference signal passes through the channel) from the filtered received signal y _i received by the signal receiving device 121 Subtraction, through step 2 as shown in the fourth figure, to obtain the interference and noise signal r after eliminating the target signal can _be expressed as follows:

最後經過第四圖中步驟三，估計出該干擾雜訊相關矩陣

可表示如下式：

Finally, through step three in the fourth figure, the interference noise correlation matrix is estimated

It can be expressed as follows:

其中，E[．]為進行取期望值運算。至此已完成R _in 的估計。

Among them, E [． ] is to perform the expected value calculation. At this point, the estimation of R _in has been completed.

，俾更新該波束權重，其表示式如下所示： In addition, in order to further enhance the accuracy of the estimation, when there are multiple sets of reference signals, the communication method can perform a plurality of steps of using the reference signals, and combine the multiple sets of complex sets of interference noise estimated by different reference signals. The correlation matrix R _in is added and averaged to enhance the accuracy of the estimation. In one embodiment, the forward-backward averaged (FBA) method of anti-coherence technology can be further used to enhance the interference and noise signals (ie, the processed filtered received signal data minus the target signal) in space. characteristics. After step 4 in the fourth figure, the final input weight calculation formula can be updated.

, in order to update the beam weight, its expression is as follows:

其中為FBA(．)為進行FBA運算，且更新R _in 的目的是最後要拿來更新波束權重。

Among them, FBA(.) is used to perform FBA operation, and the purpose of updating R _in is to finally update the beam weight.

The second way to estimate R _in is to use the characteristics of radar transceiver signals, that is, to use the step of collecting interference and noise data during the idle time of the radar, and to obtain the interference and noise through the time difference of transmitting signals between different users. The noise data is collected and R _in is estimated and updated. The process diagram is shown in Figure 5. This estimation method takes into account that systems are usually asynchronous, so interference and noise data can be obtained through the time difference in transmitting signals between different systems. After the preprocessing (down-conversion) in step 1 in Figure 5, the obtained idle period sampling signal y _{i dle} can be expressed as follows:

其中u(．)為步階函數(unit step function)、φ _u (n)為相位旋轉。接著可利用y _idle進行計算而估計出該干擾雜訊相關矩陣

。經第五圖中步驟二後之估計干擾雜訊相關矩陣

可表示如下式：

Among them, u(.) is the unit step function and φ _u ( n ) is the phase rotation. Then y _idle can be used to calculate and estimate the interference noise correlation matrix.

. Estimated interference noise correlation matrix after step 2 in Figure 5

It can be expressed as follows:

至此已完成一個idle time中R _in 的估計。由於每次系統在傳送訊號之後都會存在一個idle time，因此可不斷疊代更新

以計算用於下次偵測之權重。假設目前已歷經K個idle time，則經過第五圖中步驟三後，可更新出最後輸入權重計算公式的

，其表示式如下所示：

So far, the estimation of R _in in an idle time has been completed. Since there will be an idle time every time the system transmits a signal, it can be continuously updated iteratively.

To calculate the weight for the next detection. Assuming that K idle times have elapsed so far, after step three in the fifth figure, the final input weight calculation formula can be updated.

, its expression is as follows:

其中FBA(．)為進行FBA運算。

Among them, FBA(.) is used to perform FBA operation.

Analogous to the first way of estimating R _in , the second way of estimating R _in in equation (16) can be regarded as to further enhance the accuracy of the estimation. When there are multiple sets of idle period sampling signals, the communication The method can perform a plurality of steps of collecting interference and noise data during the idle time of the radar, and perform anti-coherence technology on multiple sets of complex interference and noise correlation matrices R _in estimated by different idle period sampling signals. The forward-backward averaged (FBA) method enhances the spatial characteristics of the interference and noise signals (ie, the processed idle period sampling signals), and the purpose of updating R _in is to finally update the beam weights.

According to other applicable viewpoints, one embodiment of the present invention also discloses a communication system 10 that performs the above communication method, including a signal transmission device 13, a radar receiving device 14 and a signal receiving device 121. The signal transmitting device 13 is used to transmit the D sub-signal to the second object 12; the radar receiving device 14 is used to receive the reflected signal of the transmitted D sub-signal reflected from the second object 12 in order to detect the first object. 11 and the second object 12, the speed of the second object 12 and the incident angle between the forward direction of the reflected signal and the forward direction of the first object 11; and the signal receiving device 121 is used to receive and demodulate the D The sub-signal is used to analyze the D sub-signal of the signal transmitting device 13 .

An embodiment of the present invention may also be a communication system (i.e., radar communication system 10) that performs the above communication method, including the above communication system, wherein the sub-signal is a model signal, and the system is a transmitter The Duoshou system is also used in the 77GHz automotive high-resolution radar frequency band.

One embodiment of the present invention is a method for transmitting and receiving radar signals, which includes modulating a signal to be transmitted (for example, including a chirp signal) through a transmission code such as a frequency index modulation code or an amplitude phase modulation code. signal) is cut into a plurality of sub-signals; wherein a specific sub-signal in the plurality of sub-signals carries one of the plurality of transmission symbols to determine the specific resource block occupied when transmitting the specific sub-signal, the BiDa improvement system ( For example: communication system 10) transmission rate purpose.

Please refer to Figure 6. In the simulation of this embodiment, a radar and communication system with a Chirp number of 128 per frame and a one transmit and eight receive (1T8R) (these 8 antennas are centrally installed on an object or user). Please refer to the seventh figure. U is defined as the number of system users. It can be seen that in the case of radar detection of multiple targets and multiple users (U=4), the proposed system (D=16) has better performance than the traditional FMCW system. Anti-interference ability, but the detection performance (Performance) will be slightly degraded due to non-linear combination. When the number of users is considered to be 12, it can be seen from the eighth figure that when the communication signal is demodulated, whether it is continuous detection or joint detection, when the number of frequency band groups increases, after scheduling and beamforming algorithms , can significantly reduce the bit error rate (Bit Error Rate, BER) of the system. It can also be seen from the eighth figure that the interference noise correlation matrix R _in can be accurately estimated using 20 reference signals, so that the beam's ability to suppress interference can be close to the lower bound (lower bound, that is: the second target incident angle is known, but unknown The best solution for interference angle of incidence). Considering the non-synchronization between systems, it can be seen from the ninth figure that the effect of using radar idle time to estimate interference is limited, and its performance cannot be close to the lower bound. However, the advantage is that there is no need to transmit any reference signals, which reduces the transmission rate.

One embodiment of the present invention proposes a linear frequency modulated continuous wave radar communication system model and design based on frequency hopping, which can greatly increase the system transmission rate. The radar target detection method can achieve good target detection effects under the model architecture proposed by the present invention. . The system proposed in one embodiment of the present invention can also significantly increase the communication transmission rate by cutting FMCW chirps without increasing bandwidth and antenna resources. It also provides a set of simplified calculation methods that can significantly reduce calculation costs and improve the efficiency of the calculation core. It is superior to similar algorithms and achieves significant improvements in angle estimation capabilities at an affordable cost. In addition, the industries that may be applied to an embodiment of the present invention include aerospace and military industry, automotive electronics, communication equipment-Internet of Things devices, consumer electronics, wearable devices, and equipment and instrument manufacturers-measuring instruments, etc., and the products that may be applied include such as : Automotive radar, military radar, IoT sensing devices, etc.

In summary, one embodiment of the present invention can indeed obtain an effect of increasing the system transmission rate by cutting the signal to be transmitted into D sub-signals through a novel communication method, and at the same time, by maximizing the received signal The proportional combination can overcome the problems caused by changing the characteristics of the received signal, and the communication signal demodulation technology used can achieve good communication symbol estimation. Therefore, those who are familiar with this art can make various modifications as the craftsman thinks, but they will not deviate from the protection sought by the patent scope attached.

10:Radar communication system

11:First object

12:Second object

121:Signal receiving device

122: Communication signal demodulation module

123: Beamforming algorithm

124: Transmission code estimation result

13:Signal transmission device

131: User scheduling algorithm

14: Radar receiving device

15:Signal transmission module

151:Channel

16:Antenna module

17: Radar target detection

18: Radar parameter estimation module

19: Target distance, speed, incident angle

Claims (13)

A frequency modulated continuous wave (FMCW) radar communication method for communication between a first object and a second object, wherein the first object has a signal transmission device and a radar receiving device, including: Executed by a signal transmission module in the signal transmission device: Cutting a signal to be transmitted containing a chirp signal of a frequency modulated continuous wave into D sub-signals; Each sub-signal carries a frequency index modulation symbol (FIM symbol); Determine a specific resource block (RB) occupied when transmitting the sub-signal based on the FIM code; and The specific resource block is used to transmit the sub-signal in order to increase the system transmission rate of the signal to be transmitted. The communication method as described in request item 1, wherein: The FIM code is a transmission FIM code; This communication method also includes: Determine a character array, the array includes D sub-arrays, and each sub-array includes n bits; sequentially reading the D sub-arrays to determine the transmission FIM code assigned to the sub-signal, so as to determine the specific resource block for transmitting each of the D sub-signals; and Executed by the signal transmission module: adding an amplitude phase modulation symbol (APM symbol) to each sub-signal to increase a system transmission capacity. The communication method as described in request item 1 or 2 further includes: An antenna module of the radar receiving device receives a reflected signal reflected from the second object after each sub-signal is transmitted; and Executed by a radar parameter estimation module of the radar receiving device: Calculating an estimated distance resolution and an estimated speed resolution based on the reflected signal; Utilize the estimated distance resolution and the estimated speed resolution to perform a maximum proportional combination to generate an estimated range Doppler map (R-D map); Pass the estimated distance map through a fixed false alarm rate (CFAR) detector to estimate a distance between the first object and the second object and a speed of the second object; and An angle estimation method is used to estimate an incident angle between the forward direction of the reflected signal and the forward direction of the first object. The communication method as described in claim 3, wherein the angle estimation method is a Fourier transform or a subspace-based angle estimation method, and the subspace-based angle estimation method is a multiple signal classification (MUSIC) or a rotation invariant Variable signal parameter estimation (ESPRIT). The communication method as described in claim 2, wherein the second object has a signal receiving device, and the communication method further includes: Executed by a communication signal demodulation module of the signal receiving device: Set a sampling frequency of the signal receiving device to the system bandwidth; Receive each of the transmitted sub-signals according to the sampling frequency; Use an energy detector to check and calculate the frequency band energy of each sub-signal after transmission; Take out an estimated resource area corresponding to the frequency band with the largest energy block; Obtain an estimated FIM symbol based on the estimated resource block; Using a band-pass filter (BPF) to reduce interference from other frequency bands other than the frequency band corresponding to the estimated FIM symbol to filter out one of the filtered received signals in the estimated resource block; and A Maximum-Likelihood (ML) detector is used to restore one of the estimated APM symbols contained in the filtered received signal. The communication method as described in claim 2, wherein the second object has a signal receiving device, and the communication method further includes: Executed by a communication signal demodulation module of the signal receiving device: receiving the transmitted D sub-signal; and A Maximum-Likelihood (ML) detector is used to check at once the plurality of FIM symbols corresponding to the resource blocks that may transmit the sub-signal and the plurality of APM symbols that the sub-signal may carry. combination of codes, and obtain an estimated FIM code and an estimated APM code with the highest probability among a plurality of combinations of the FIM code and the APM code. The communication method described in request item 6 further includes: The signal receiving device combines W resource blocks into G groups of frequency bands, so that each group of frequency bands has a specific number of resource blocks. Different groups of frequency bands of the G group of frequency bands are allocated to different users to avoid One multi-user interference; Allocate the first object to a frequency band with E resource blocks in the G group of frequency bands, and determine the specific resource block occupied when transmitting the sub-signal in the E resource blocks through the FIM symbol ;as well as When the number of different users is greater than the number of frequency bands in the G group, the signal is transmitted A user scheduling algorithm in the device avoids the multi-user interference, and a beamforming algorithm in the signal receiving device suppresses multi-user interference between different users using the same set of frequency bands. The communication method as described in claim 7, wherein the user scheduling algorithm performs the following steps: Allocate the frequency band of Group G to the different users; Maximize an average signal to interference plus noise ratio (SINR) among the different users; and A greedy scheduling algorithm is used to optimize and continuously allocate each of the G groups of frequency bands to the different users. The communication method as described in request item 7 further includes: After determining a scheduling result, the user scheduling algorithm uses multiple antennas of the signal receiving device and the beamforming algorithm to perform beamforming with a maximum signal to interference plus noise ratio (MSINR) to further inhibit usage. A power of multi-user interference between different users in the same set of frequency bands to maintain a target signal gain and reduce an interference energy; and Use a reference signal or interference and noise data collected during the radar's idle time to estimate an interference noise correlation matrix, calculate a beam weight based on it, and then use the obtained beam weight to implement a part of the beamforming algorithm. Beamforming step, where: The step of using the reference signal is to subtract a target signal estimated by the reference signal after being transmitted through a channel from a filtered received signal received by the signal receiving device to obtain a target signal after eliminating the target signal. interference and noise signals, and estimate the interference-noise correlation matrix based on them; and The step of collecting interference and noise data during the idle time of the radar is to obtain interference and noise data through the time difference between one of the transmission signals between different users, and then use a preprocessed idle period sampling signal. Calculate and estimate the interference noise correlation matrix accordingly. According to the communication method described in claim 9, the steps of using the reference signal or collecting interference and noise data during the idle time of the radar are performed multiple times, and the estimated complex sets of interference and noise correlation matrices are added and obtained. An average value to enhance the accuracy of an estimate and/or use a forward-backward averaged (FBA) anti-coherence technology to enhance the characteristics of the interference and noise signals in a space in order to update the beam weight . A communication system that performs the communication method described in claim 1, including: The signal transmission device is used to transmit the D sub-signal to the second object; The radar receiving device is used to receive a reflected signal of the transmitted D sub-signal reflected from the second object, so as to detect the distance between the first object and the second object, and the distance between the second object and the first object. a speed and an angle of incidence between the direction of travel of the reflected signal and the direction of travel of the first object; and A signal receiving device is used to receive and demodulate the D sub-signal to analyze the D sub-signal of the signal transmitting device. A communication system that performs the communication method as described in claim 1, including: the communication system as described in claim 11, wherein the sub-signal is a model signal, and the system is a transmit-multiple-receive system and is used in a 77GHz car high-resolution radar frequency band. A radar signal transmission and reception method, including: Cut a signal to be transmitted into a plurality of sub-signals; Provide plural transmission codes; and A specific sub-signal among the plurality of sub-signals is allowed to carry one of the plurality of transmission symbols to determine a specific resource block occupied when transmitting the specific sub-signal, in order to achieve the purpose of increasing a system transmission rate.

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