Downlink channel estimation method and vehicle-mounted operation control system

Abstract

The invention relates to the technical field of heavy haul railway train operation control, in particular to a downlink channel estimation method and a vehicle-mounted operation control system.The method comprises the steps that a target signal is received, and an actual pilot frequency sequence in the target signal is extracted; estimating a channel response based on the actual pilot frequency sequence and a preset reference pilot frequency sequence to obtain a first time domain response result of the channel; detecting whether a second time domain response result of a second vehicle-mounted radio station to the actual pilot frequency sequence is received, and when the second time domain response result is received, performing weighted summation on the first time domain response result and the second time domain response result based on a preset calculation rule to obtain a target time domain response result; and converting the target time domain response result from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain. According to the invention, the standby vehicle-mounted communication equipment in the train control system is multiplexed, channel estimation of the LTE downlink channel is assisted under the condition that the system complexity is slightly increased, and the channel estimation accuracy is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of heavy-load railway train operation control, and in particular to a downlink channel estimation method and a vehicle-mounted operation control system. Background Art

[0002] Some heavy-haul railway lines have adopted operator networks to carry heavy-haul railway operation control system information. Downlink channel estimation of LTE network refers to a series of processing processes in the LTE system to obtain downlink channel information in order to perform channel compensation at the receiving end, thereby improving the performance of the entire system.

[0003] However, due to signal fluctuations or distortions caused by various random factors (such as electromagnetic interference, thermal noise, multipath effects, etc.) during the communication process, the downlink channel estimation results are easily disturbed and inaccurate. The accuracy of channel estimation directly affects the quality of signal reception, which in turn affects the accuracy of the carrier frequency verification of the on-board automatic train protection (ATP), causing the ATP device to misjudge when performing carrier frequency verification. This misjudgment will cause the ATP device to mistakenly believe that the signal is interfered with or comes from the wrong track section, thereby triggering the safety measures of mobile authorization calculation retraction and braking, increasing the safety risk of rear-end collision with the rear train, as well as the risk of delaying the train operation time and affecting the overall operation plan.

[0004] The current LTE network downlink channel estimation mainly uses the least squares (LS) and discrete fast Fourier transform (DFT), which can meet the operator's network channel estimation needs. However, the heavy-duty railway operation control system has higher requirements for the signal quality, reliability and stability of the train-to-ground wireless communication. The traditional LS and DFT need to be improved in the heavy-duty railway communication application process. Summary of the invention

[0005] The present disclosure provides a downlink channel estimation method and a vehicle-mounted operation control system to solve the problem in the prior art that the accuracy of the results of downlink channel estimation using traditional LS and DFT methods is difficult to meet the requirements of heavy-load railway communications.

[0006] In a first aspect, the present disclosure provides a downlink channel estimation method, the method being applied to a first vehicle radio station of a vehicle operation control system, the vehicle operation control system comprising the first vehicle radio station and a second vehicle radio station, the method comprising:

[0007] receiving a target signal, and extracting an actual pilot sequence in the target signal;

[0008] estimating a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel;

[0009] detecting whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting an actual pilot sequence in the target signal, and performing channel response estimation calculation based on the actual pilot sequence and the reference pilot sequence;

[0010] When receiving the second time domain response result of the channel sent by the second vehicle-mounted radio station, based on a preset weight rule, weighted summing the first time domain response result and the second time domain response result is performed to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1;

[0011] The target time domain response result is converted from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

[0012] In one embodiment, after the step of detecting whether the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, the method further includes:

[0013] When the second time domain response result of the channel sent by the second vehicle-mounted radio station is not received, the first time domain response result is converted from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

[0014] In one embodiment, the step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain a first time domain response result of the channel includes:

[0015] Based on the actual pilot sequence and the preset reference pilot sequence, a channel estimation result on each subcarrier is obtained by least squares calculation;

[0016] Perform an inverse discrete fast Fourier transform on the channel estimation result on each of the subcarriers to obtain the first time domain response result.

[0017] In one embodiment, in the step of performing an inverse discrete fast Fourier transform on the channel estimation result on each of the subcarriers to obtain the first time domain response result, the calculation formula of the first time domain response result is as follows:

[0018]

[0019] in, is the first time domain response result, w(n) is the noise within the cyclic prefix, L is the length of the cyclic prefix, and h(n) is the time domain response result after the inverse discrete fast Fourier transform of the channel estimation result on the nth subcarrier.

[0020] In one embodiment, the step of performing weighted summation on the first time domain response result and the second time domain response result based on a preset weight rule to obtain a target time domain response result includes:

[0021] The first time domain response result and the second time domain response result are averaged to obtain a target time domain response result of the channel.

[0022] In one embodiment, after the step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain the first time domain response result of the channel, the step further includes:

[0023] The first time domain response result is sent to the second vehicle radio station, so that the second vehicle radio station performs weighted summation on the first time domain response result and the second time domain corresponding result based on a preset weight rule to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1.

[0024] In a second aspect, the present disclosure provides a vehicle-mounted operation control system, including a first vehicle-mounted radio station and a second vehicle-mounted radio station, wherein:

[0025] The first vehicle-mounted radio station is used to receive a target signal, extract an actual pilot sequence in the target signal; estimate a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel; detect whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting the actual pilot sequence in the target signal, and calculating based on the actual pilot sequence and the reference pilot sequence; when the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, based on a preset weight rule, weighted summing the first time domain response result and the second time domain corresponding result is obtained to obtain a target time domain response result, wherein the sum of a first weight corresponding to the first time domain response result and a second weight corresponding to the second time domain response result is 1; converting the target time domain response result from time domain to frequency domain to obtain a downlink channel estimation result based on frequency domain;

[0026] The second vehicle-mounted radio station is used to receive the target signal, extract the actual pilot sequence in the target signal, calculate the second time domain response result based on the actual pilot sequence and the reference pilot sequence, and send the second time domain response result to the first vehicle-mounted radio station.

[0027] In a third aspect, the present disclosure provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above aspects.

[0028] In a fourth aspect, the present disclosure provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method described in the above aspects when executed by a processor.

[0029] In a fifth aspect, the present disclosure provides a computer program product, including a computer program / instructions, which implements the steps of the method described in the above aspects when the computer program is executed by a processor.

[0030] The present disclosure provides a downlink channel estimation method and a vehicle-mounted operation control system, which respectively perform channel estimation through a first vehicle-mounted radio station and a second vehicle-mounted radio station, and calculate the time domain response result of the channel based on the actual pilot sequence and the preset reference pilot sequence. Subsequently, the two time domain response results are summed by a preset weight coefficient to obtain the target time domain response result of the channel. This dual-end estimation and fusion method averages interference and noise to a certain extent, reduces the error caused by single radio station estimation, and makes the final channel estimation result more stable and reliable, and has higher fault tolerance.

[0031] In addition, by reusing the spare on-board communication equipment in the operation control system, on the one hand, the idle communication resources of the spare radio station are fully utilized to avoid idleness and waste of resources; on the other hand, it is realized to assist in channel estimation of the LTE downlink channel and increase the accuracy of channel estimation while increasing a small amount of system complexity. Although reusing spare radio stations will increase the system complexity to a certain extent, compared with solutions such as purchasing new equipment and redeployment, this increase in complexity is relatively smaller, the cost is controllable, and the impact on the overall performance and stability of the system is also smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0033] Figure 1 A schematic diagram of a flow chart of a downlink channel estimation method provided by an embodiment of the present disclosure;

[0034] Figure 2 A structural block diagram of a downlink channel estimation software provided by an embodiment of the present disclosure;

[0035] Figure 3 A schematic diagram of a flow chart of another downlink channel estimation method provided by an embodiment of the present disclosure;

[0036] Figure 4 This is a block diagram of the internal structure of a downlink channel estimation device provided in an embodiment of the present disclosure.

[0037] In the drawings, the same reference numerals are used for the same components, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, and to fully understand and implement how the present disclosure applies technical means to solve technical problems and achieve the corresponding technical effects, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only embodiments of a part of the present disclosure, not all of the embodiments. The embodiments of the present disclosure and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the scope of protection of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present disclosure.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0040] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0041] Embodiment 1

[0042] Figure 1 A schematic diagram of a downlink channel estimation method provided by an embodiment of the present disclosure. Figure 1 As shown, a downlink channel estimation method is applied to a first vehicle radio station of a vehicle operation control system, the vehicle operation control system includes the first vehicle radio station and the second vehicle radio station, the method includes:

[0043] Step 110, receiving a target signal, and extracting an actual pilot sequence in the target signal;

[0044] The on-board operation control system is used to achieve wireless connection with the ground base station through the on-board radio, so as to realize the exchange of heavy-load train and ground control information. The ground base station transmits the train control data sent by the on-board radio to the ground core network, and then transmits it to the ground train control equipment. The ground train control equipment sends the train control data to be sent to the ground base station through the ground core network. The ground base station sends it to the on-board radio through wireless communication, and then transmits it to the on-board train control equipment.

[0045] In this embodiment, the first vehicle radio and the second vehicle radio are deployed in a primary-backup redundant manner, and are equipped with two pairs of two-port roof LTE antennas. The roof antenna and the vehicle radio are connected in a cross connection manner. The LTE downlink channels of the first vehicle radio and the second vehicle radio are close, and the channel estimation results can be mutually referenced to improve the communication quality.

[0046] The target signal refers to the specific wireless signal that the vehicle radio needs to receive and process. It can be a variety of signals such as voice, data, control instructions, etc. The signal can come from other vehicles, ground base stations, control centers or other wireless communication equipment. The vehicle radio receives the wireless signal in the air through its antenna and converts it into an electrical signal for processing. The processing process includes steps such as signal amplification, filtering, and demodulation in order to extract the actual pilot sequence from the received signal.

[0047] In wireless communication, a pilot sequence is a known signal sequence used to assist the receiving end in signal synchronization, channel estimation, signal demodulation and other processes. In this embodiment, a known pilot sequence is inserted into the target signal. When the target signal is transmitted to the receiving end (the first vehicle-mounted radio station) through the channel, the target signal is affected by channel noise and interference during transmission, resulting in a decrease in the quality of the received signal. These noises and interferences may change the waveform, amplitude or phase of the pilot sequence, so that there is a deviation between the actual pilot sequence extracted and the known pilot sequence.

[0048] After receiving the target signal, the first vehicle radio station will use the preset or known pilot sequence pattern to identify and extract the actual pilot sequence from the received signal. For example, it can be extracted by matching filtering, correlation detection, etc., that is, the received target signal is correlated with the known pilot sequence to find the part that is most similar to the pilot sequence. By comparing the actual pilot sequence with the known pilot sequence, the receiving end can evaluate the transmission characteristics of the channel, such as attenuation, phase shift, etc., and correct the received signal accordingly.

[0049] Step 120, estimating a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel;

[0050] The reference pilot sequence is the known pilot sequence mentioned above, which is a known signal sequence that has been determined and stored in the vehicle radio during the system design phase. The first vehicle radio compares and matches the actual pilot sequence with the preset reference pilot sequence, and evaluates the impact of the channel on the pilot signal (i.e., channel response) by calculating indicators such as correlation or error between the two.

[0051] In this embodiment, the first time domain response result shows the influence of the channel on the transmitted signal in the time domain, including characteristics such as signal attenuation and delay. The first time domain response result is an important basis for subsequent signal processing and can be used in signal synchronization, equalization and other processing processes to improve the transmission quality and reliability of the signal.

[0052] Step 130, detecting whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting an actual pilot sequence in the target signal, and performing channel response estimation calculation based on the actual pilot sequence and the reference pilot sequence;

[0053] In this embodiment, the second vehicle radio also stores a reference pilot sequence, also receives the target signal, and extracts the actual pilot sequence in the target signal, performs channel response estimation based on the reference pilot sequence and the actual pilot sequence, and obtains a second time domain response result. The process of calculating the second time domain response result is similar to that of the first vehicle radio, and will not be repeated here.

[0054] After the second vehicle radio calculates the second time domain response result, it sends the result to the first vehicle radio, so that the first vehicle radio can refer to the two time domain response results to reduce the error of the time domain response result, such as the error caused by normal distribution or the error caused by damage to some cable adapters.

[0055] Step 140, when the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, based on a preset weight rule, weighted summing the first time domain response result and the second time domain response result is performed to obtain a target time domain response result, wherein the sum of a first weight corresponding to the first time domain response result and a second weight corresponding to the second time domain response result is 1;

[0056] It can be understood that the time domain response directly reflects the changes in the signal over time, including the arrival time, delay, attenuation, etc. of the signal. In the vehicle communication environment, due to the mobility of the vehicle and the complexity of the surrounding environment, the time domain characteristics of the signal are particularly important. By weighting and summing the responses from different vehicle radio stations in the time domain, the actual changes of the signal during the propagation process can be more directly considered. Although frequency domain analysis is also widely used in signal processing, the frequency domain response reflects more the distribution of the signal at different frequencies rather than the specific changes of the signal in time. Therefore, in vehicle communications, directly weighting and summing the frequency domain response may not accurately reflect the time domain characteristics of the signal such as delay and attenuation during the propagation process. In this embodiment, the first time domain response result and the second time domain response result calculated by the first radio station and the second radio station respectively are weighted and summed, which can improve the accuracy of channel estimation and system robustness, and more accurately reflect the time domain characteristics of the signal.

[0057] The values ​​of the first weight and the second weight can be set according to the actual application situation, and the values ​​of the first weight and the second weight can be the same or different. For example, if the first vehicle radio is more stable in performance, and historical data shows that its channel estimation results are more accurate, then the first vehicle radio can be given a higher weight. For example, if the first weight is set to 0.7 or higher, the second weight is reduced to 0.3 or lower accordingly. If the vehicle's current communication environment is complex and there are strong interference sources, the weight of the second vehicle radio can be appropriately increased to deal with possible signal loss or distortion problems.

[0058] In one embodiment, the first weight and the second weight can also be adjusted in combination with the fault detection mechanism. When it is detected that the first vehicle radio station or the second vehicle radio station fails or the performance is degraded, it can automatically switch to another radio station and adjust the weight accordingly. For example, when it is detected that the performance of the first vehicle radio station is degraded, if the first weight is 0.5, it is lowered to 0.3, and the second weight is adjusted to 0.7. When it is detected that any one of the vehicle radio stations fails, the weight corresponding to the other radio station with normal performance is adjusted to 1.

[0059] In one embodiment, the performance of the first vehicle radio station is similar to that of the second vehicle radio station, so the first weight is set to be the same as the second weight, that is, the first time domain response result and the second time domain response result are averaged.

[0060] In one embodiment, the number of second vehicle radio stations is multiple, for example, the number of first vehicle radio stations is 1, and the number of second vehicle radio stations is 2, that is, the first vehicle radio station receives the time domain response results calculated from the two second vehicle radio stations respectively, and according to the preset calculation rules, sets the first weight to 0.6, and the second weights of the two second vehicle radio stations are 0.2 respectively, and then weighted summation is performed on the three time domain response results respectively.

[0061] Step 150: Convert the target time domain response result from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

[0062] Wireless channels are usually frequency selective, that is, signals of different frequencies will be subject to different degrees of attenuation and phase shift during transmission. The time domain signal and the frequency domain signal are converted to each other through discrete Fourier transform and its inverse transform, and the target time domain response result is converted into the target frequency domain response result, and the frequency response of the channel on each subcarrier can be obtained. Therefore, it is more intuitive and effective to observe and process channel characteristics in the frequency domain, which can provide accurate channel state information for subsequent coherent demodulation, and facilitate the subsequent equalization, compensation and other operations according to the channel characteristics to reduce the impact of the channel on the signal.

[0063] In summary, the present disclosure provides a downlink channel estimation method, in which the first vehicle-mounted radio station and the second vehicle-mounted radio station respectively perform channel estimation, and calculate the time domain response result of the channel based on the actual pilot sequence and the preset reference pilot sequence. Subsequently, the two time domain response results are summed by a preset weight coefficient to obtain the target time domain response result of the channel. This dual-end estimation and fusion method averages interference and noise to a certain extent, reduces the error caused by single radio station estimation, and makes the final channel estimation result more stable and reliable, and has higher fault tolerance.

[0064] In addition, by reusing the spare on-board communication equipment in the operation control system, on the one hand, the idle communication resources of the spare radio station are fully utilized to avoid idleness and waste of resources; on the other hand, it is realized to assist in channel estimation of the LTE downlink channel and increase the accuracy of channel estimation while increasing a small amount of system complexity. Although reusing spare radio stations will increase the system complexity to a certain extent, compared with solutions such as purchasing new equipment and redeployment, this increase in complexity is relatively smaller, the cost is controllable, and the impact on the overall performance and stability of the system is also smaller.

[0065] Embodiment 2

[0066] On the basis of the above embodiment, after the step of detecting whether the second time domain response result of the channel sent by the second vehicle radio station is received, it also includes: when the second time domain response result of the channel sent by the second vehicle radio station is not received, converting the first time domain response result from time domain to frequency domain to obtain a downlink channel estimation result based on frequency domain.

[0067] It is understandable that if the system always waits for channel estimation results from all vehicle radios, unnecessary delays may occur in some abnormal situations, such as network congestion, node failure, or signal interference. When the system confirms that it cannot receive the channel estimation result from the second vehicle radio, the first vehicle radio will immediately use its own channel estimation result to continue subsequent processing, thereby optimizing resource usage and reducing waiting time. Although the channel estimation result based on only one vehicle radio may not be as accurate as the average or weighted sum of the results based on multiple vehicle radios, it still provides some information about the channel status, allowing the system to take appropriate measures to respond.

[0068] Therefore, when the channel estimation result of the second vehicle-mounted radio station is not received, the system only needs to convert the first time domain response result calculated by itself into a frequency domain response result to obtain the downlink channel estimation result. This step simplifies the processing flow, reduces the computational complexity and potential delays. In addition, in a wireless communication environment, due to the presence of factors such as signal attenuation, multipath effects, and interference, the channel state changes dynamically. The method of this embodiment can flexibly respond to these changes and can continue to operate when it is unable to receive channel estimation results from other vehicle-mounted radio stations.

[0069] The "not received" in the second time domain response result of the channel sent by the second vehicle-mounted radio station may be that the data was not successfully received within the preset time window. The preset time window can be determined according to multiple factors such as system synchronization, channel conditions, protocol specifications, system resources and actual application requirements. For example, in a communication system, it is usually necessary to maintain a certain degree of synchronization between nodes. Therefore, the preset time window may be related to the synchronization cycle of the system. For example, if the system synchronizes once every T seconds and expects to receive all necessary data within each synchronization cycle, the time limit for not receiving can be set to be determined as not receiving if the second time domain response result is not received within T seconds. Channel conditions (such as signal strength, interference level, transmission rate, etc.) will also affect the reception time of data. Under poor channel conditions, the transmission and reception of data may be delayed or fail. Therefore, the preset time window can also take into account changes in channel conditions and be adjusted accordingly, such as appropriately extending or reducing the reception waiting time based on the basic waiting reception time according to the poor level of channel conditions.

[0070] Embodiment 3

[0071] Based on the above embodiment, the step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain the first time domain response result of the channel includes: obtaining the channel estimation result on each subcarrier by least squares calculation based on the actual pilot sequence and the preset reference pilot sequence; and performing an inverse discrete fast Fourier transform on the channel estimation result on each of the subcarriers to obtain the first time domain response result.

[0072] In this embodiment, the actual pilot sequence is Y(m), m=0, 1...N-1, where N is the sequence length;

[0073] The preliminary channel estimation result is obtained by the least squares method. The specific calculation process is as follows:

[0074] Assume that the reference pilot sequence is X(m), m=0, 1...N-1;

[0075] Then the channel response R of the pilot position can be expressed as Y=XR+W, where R=[R(0), R(1)...R(N-1)] T , W is the noise in the pilot data.

[0076] According to the least squares method, in order to make the channel estimation result as accurate as possible, it is necessary to minimize the sum of squares of the errors between the actual received value and the estimated value, which can be expressed by the cost function K:

[0077] K=(YY E ) H (YY E ), where Y is the actual pilot sequence, and Y E is the value of channel estimation;

[0078] Y E =XR E Substitute it into, and now the R of K E Find the partial derivative and make it 0, then this is the minimum value of K:

[0079]

[0080] Simplifying, we can get the following calculation formula:

[0081]

[0082] Ignoring the mutual interference noise between subcarriers, the channel estimation result on each subcarrier is It can be expressed as follows:

[0083]

[0084] The calculation process of reducing the noise outside the cyclic prefix by inverse discrete fast Fourier transform operation and obtaining the local channel estimation result in the time domain is as follows:

[0085] right Perform an inverse discrete fast Fourier transform operation on each subcarrier, and the channel impulse response (or the first time domain response result) at the nth point is as follows:

[0086]

[0087] Where W(n) is the noise inside the cyclic prefix, W'(n) is the noise outside the cyclic prefix, and L is the length of the cyclic prefix.

[0088] In the time domain, it can be considered that the first L sample points store all the valid information of the channel, so the noise of W'(n) can be set to 0, and the final first time domain response result is:

[0089]

[0090] For easy distinction, the first time domain response result of the first vehicle radio is: The second time domain response result received from the second vehicle radio is

[0091] Embodiment 4

[0092] On the basis of the above embodiment, the step of performing weighted summation of the first time domain response result and the second time domain response result based on a preset weight rule to obtain a target time domain response result includes: performing mean calculation on the first time domain response result and the second time domain response result to obtain the target time domain response result of the channel.

[0093] In this embodiment, the first vehicle radio station receives the second vehicle radio station channel estimation result (second time domain response result) corresponding to the actual pilot sequence Y(m) ), then take the average of the two to get the target time domain response result The specific calculation formula is as follows:

[0094]

[0095] After that, the target time domain response result Perform fast Fourier transform to obtain the target time domain response result H of the channel DFT (k), the specific calculation formula is as follows:

[0096]

[0097] If the local station does not receive the channel estimation result of the second vehicle radio station corresponding to the actual pilot sequence Y(m) Then only the first time domain channel estimation result of the first vehicle radio station is subjected to fast Fourier transform to obtain the target time domain response result H of the channel. DFT (k):

[0098]

[0099] Embodiment 5

[0100] On the basis of the above embodiment, after the step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain the first time domain response result of the channel, it also includes: sending the first time domain response result to the second vehicle radio station, so that the second vehicle radio station performs weighted summation on the first time domain response result and the second time domain corresponding result based on a preset weight rule to obtain the target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1.

[0101] In this embodiment, the second vehicle-mounted radio station runs in parallel with the first vehicle-mounted radio station, and respectively receives the time domain response results calculated by the opposite end radio station and then performs weighted summation with the time domain response results calculated by itself. By performing calculations and weighted summation separately by the two vehicle-mounted radio stations, more data samples can be used, and each radio station can independently process the received signal, reducing the error caused by signal interference or noise of a single radio station, thereby enhancing the robustness and accuracy of channel estimation. The parallel operation system design provides redundancy. Even if one of the vehicle-mounted radio stations fails or its performance degrades, the other radio station can still work normally, ensuring the continuity and reliability of the entire system.

[0102] Embodiment 6

[0103] In this embodiment, the present disclosure provides a vehicle-mounted operation control system, including a first vehicle-mounted radio station and a second vehicle-mounted radio station, wherein:

[0104] The first vehicle-mounted radio station is used to receive a target signal, extract an actual pilot sequence in the target signal; estimate a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel; detect whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting the actual pilot sequence in the target signal, and calculating based on the actual pilot sequence and the reference pilot sequence; when the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, based on a preset weight rule, weighted summing the first time domain response result and the second time domain corresponding result is obtained to obtain a target time domain response result, wherein the sum of a first weight corresponding to the first time domain response result and a second weight corresponding to the second time domain response result is 1; converting the target time domain response result from time domain to frequency domain to obtain a downlink channel estimation result based on frequency domain;

[0105] The second vehicle-mounted radio station is used to receive the target signal, extract the actual pilot sequence in the target signal, calculate the second time domain response result based on the actual pilot sequence and the reference pilot sequence, and send the second time domain response result to the first vehicle-mounted radio station.

[0106] In one embodiment, the first vehicle-mounted radio station and the second vehicle-mounted radio station can implement the downlink channel estimation method described in any one of the above embodiments when in operation.

[0107] Embodiment 7

[0108] Based on the above embodiment, this embodiment provides an application example. In this embodiment, Figure 2 As shown, a downlink channel estimation software structure block diagram is provided, including:

[0109] The software initialization module 210 is responsible for starting the software, reading related parameters, and reading main and standby information;

[0110] The first calculation module 220 is used to extract the corresponding channel estimation pilot sequence after the vehicle-mounted radio station receives the signal, and calculate the preliminary result of the channel estimation in the frequency domain by the least square method;

[0111] The second calculation module 230 is used to perform an inverse discrete fast Fourier transform on the preliminary result of the channel frequency domain estimation calculated by the first calculation module to eliminate the noise outside the effective response area in the time domain and obtain a time domain response result;

[0112] The master-slave interaction module 240 is used to perform information interaction between multiple vehicle-mounted communication radio stations, including sending the time domain response result of the local vehicle-mounted radio station to other radio stations, and continuously obtaining the time domain channel estimation results of other radio stations;

[0113] The channel estimation module 250 is used to summarize the time domain channel estimation results of the local vehicle radio and calculate the average value of the time domain channel estimation; and to organize and output the frequency domain channel estimation results by performing fast Fourier transform on the average value of the time domain channel estimation.

[0114] Based on the above downlink channel estimation software structure diagram, Figure 3 As shown, this embodiment also provides another downlink channel estimation method, which is applied to the on-board radio communication system in the heavy-load railway train control system. By multiplexing the backup on-board radio of the on-board radio communication system, it assists in channel estimation of the LTE downlink channel while slightly increasing the system complexity, thereby increasing the channel estimation accuracy.

[0115] The details are as follows:

[0116] 1. After the software is started, the system initialization module is started first, and the relevant preset parameters of the initialization are read, and the pilot sequence Y(m) of the local radio station is continuously obtained, where m=0, 1...N-1, and N is the sequence length;

[0117] The preliminary channel estimation result is obtained through the LS estimation algorithm.

[0118] Assume that the original pilot sequence is X(m), where m=0, 1...N-1;

[0119] Then the channel response R of the pilot position can be expressed as Y = XR + W, where R = [R(0), R(1) ... R(N-1)] T , W is the noise in the pilot data.

[0120] According to the LS (least squares) algorithm, in order to make the channel estimation result as accurate as possible, it is necessary to minimize the sum of squares of the errors between the actual received value and the estimated value, which can be expressed by the cost function K:

[0121] K=(YY E ) H (YY E ), where Y is the pilot actually received, and Y E is the value of channel estimation;

[0122] Y E =XR E Substitute it into, and now the R of K E Find the partial derivative to make it 0, which is the minimum value of K

[0123]

[0124] Simplifying, we can get

[0125] Ignoring the mutual interference noise between subcarriers, the LS channel estimation result on each subcarrier is for:

[0126] Where m=0, 1...N-1.

[0127] Through the IFFT (Inverse Discrete Fast Fourier Transform) operation, the noise outside the cyclic prefix is ​​reduced to obtain the local channel estimation result in the time domain:

[0128] right If an inverse discrete fast Fourier transform operation is performed on each subcarrier of , the channel impulse response (CIR) of the nth point is:

[0129]

[0130] Where W(n) is the noise inside the cyclic prefix, W'(n) is the noise outside the cyclic prefix, and L is the length of the cyclic prefix.

[0131] In the time domain, it can be assumed that the first L sample points store all the valid information of the channel, so the noise of W'(n) can be set to 0, and the result is as follows:

[0132]

[0133] In order to facilitate the distinction, the local time domain channel estimation result is represented by The received time domain channel estimation result of the peer device is used express.

[0134] 2. After the system starts, the active and standby interaction modules:

[0135] Within the preset time, continue to receive the time domain channel estimation results sent by the other station

[0136] Each time the channel estimation result in the local time domain is obtained After that, the channel estimation result in the local time domain is sent to the other station.

[0137] 3. Channel estimation summary module

[0138] If the local station receives the channel estimation result of the peer station corresponding to the pilot sequence Y(m) Take the average of the two to get the target time domain response result

[0139]

[0140] After that, the target time domain response result Perform fast Fourier transform to obtain the target time domain response result H of the channel DFT (k), the specific calculation formula is as follows:

[0141]

[0142] If the local station does not receive the channel estimation result of the second vehicle radio station corresponding to the actual pilot sequence Y(m) Then only the first time domain channel estimation result of the first vehicle radio station is subjected to fast Fourier transform to obtain the target time domain response result H of the channel. DFT (k):

[0143]

[0144] In summary, compared with the existing heavy-haul railway vehicle-ground communication network optimization system, the method of this embodiment has the following beneficial effects:

[0145] 1. It can utilize the idle communication resources of the heavy-load railway train control system;

[0146] 2. The time domain channel estimation data of the peer radio station can be used to reduce errors caused by normal distribution, RF errors, and errors caused by damage to some cable adapters;

[0147] 3. It can improve channel estimation performance without increasing additional complexity or introducing other noise;

[0148] 4. Software deployment and upgrade are fast and low-cost, with little impact on other devices in the system.

[0149] Embodiment 8

[0150] Based on the above embodiments, Figure 4 As shown, this embodiment provides a downlink channel estimation device, which is applied to a first vehicle radio station of a vehicle operation control system, wherein the vehicle operation control system includes a first vehicle radio station and a second vehicle radio station, and the device includes:

[0151] The extraction module 410 is used to receive a target signal and extract an actual pilot sequence in the target signal;

[0152] A time domain response calculation module 420, configured to estimate a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel;

[0153] The detection module 430 is used to detect whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting an actual pilot sequence in the target signal, and performing a channel response estimation calculation based on the actual pilot sequence and the reference pilot sequence;

[0154] The first calculation module 440 is used for, when receiving the second time domain response result of the channel sent by the second vehicle-mounted radio station, performing weighted summation on the first time domain response result and the second time domain response result based on a preset weight rule to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1;

[0155] The conversion module 450 is used to convert the target time domain response result from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

[0156] In one embodiment, it also includes:

[0157] The second calculation module is used to convert the first time domain response result from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain when the second time domain response result of the channel sent by the second vehicle-mounted radio station is not received.

[0158] In one embodiment, the time domain response calculation module includes:

[0159] A least squares calculation unit, configured to obtain a channel estimation result on each subcarrier by least squares calculation based on the actual pilot sequence and a preset reference pilot sequence;

[0160] The inverse discrete fast Fourier transform calculation unit is used to perform an inverse discrete fast Fourier transform on the channel estimation result on each of the subcarriers to obtain the first time domain response result.

[0161] In one embodiment, the first calculation module includes:

[0162] The mean calculation unit is used to perform mean calculation on the first time domain response result and the second time domain response result to obtain a target time domain response result of the channel.

[0163] In one embodiment, it also includes:

[0164] A sending module is used to send the first time domain response result to the second vehicle radio station, so that the second vehicle radio station performs weighted summation on the first time domain response result and the second time domain corresponding result based on a preset weight rule to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1.

[0165] For the specific definition of the downlink channel estimation device, please refer to the definition of the downlink channel estimation method in the above text, which will not be repeated here. Each unit in the above downlink channel estimation device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above units can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above units.

[0166] Embodiment 9

[0167] On the basis of the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above embodiments.

[0168] In some implementations of this embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0169] In some implementations of this embodiment, a computer program product is provided, including a computer program / instructions, and when the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0170] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components to execute the method in the above embodiments.

[0171] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, for example, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (such as hard disks, floppy disks, solid-state drives, removable disks, etc.).

[0172] The computer-readable storage medium may also store at least one computer executable program / instruction, which may be, for example, a computer-readable instruction. The computer-readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The computer-readable storage medium may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device runs the computer-readable instructions stored on the computer-readable storage medium, the various methods described above may be performed.

[0173] In addition, the computer device may also include (but not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (eg, keyboard, mouse, speaker, etc.), etc.

[0174] The processor may communicate with external devices via an I / O bus via a wired or wireless network.

[0175] In one embodiment, the at least one computer executable instruction may also be compiled into or constitute a software product / computer program product, wherein one or more computer executable instructions are executed by a processor to perform the various functions and / or method steps in the embodiments described in the present technology.

[0176] In the embodiments provided in the present disclosure, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the above-mentioned module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0177] It should be noted that in the present disclosure, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element limited by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0178] Although the embodiments disclosed in the present disclosure are as above, the above contents are only embodiments adopted for facilitating the understanding of the present disclosure and are not intended to limit the present disclosure. Any technician in the technical field to which the present disclosure belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present disclosure, but the scope of patent protection of the present disclosure shall still be subject to the scope defined in the attached claims.

Claims

1. A downlink channel estimation method, characterized in that: The method is applied to a first vehicle radio station of a vehicle operation control system, wherein the vehicle operation control system includes the first vehicle radio station and the second vehicle radio station, and the method includes: receiving a target signal, and extracting an actual pilot sequence in the target signal; estimating a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel; detecting whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting an actual pilot sequence in the target signal, and performing channel response estimation calculation based on the actual pilot sequence and the reference pilot sequence; When receiving the second time domain response result of the channel sent by the second vehicle-mounted radio station, based on a preset weight rule, weighted summing the first time domain response result and the second time domain response result is performed to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1; The target time domain response result is converted from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

2. The method according to claim 1, characterized in that After the step of detecting whether the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, the method further includes: When the second time domain response result of the channel sent by the second vehicle-mounted radio station is not received, the first time domain response result is converted from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain.

3. The method according to claim 1, characterized in that The step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain a first time domain response result of the channel comprises: Based on the actual pilot sequence and the preset reference pilot sequence, a channel estimation result on each subcarrier is obtained by least squares calculation; Perform an inverse discrete fast Fourier transform on the channel estimation result on each of the subcarriers to obtain the first time domain response result.

4. The method according to claim 3, characterized in that In the step of performing an inverse discrete fast Fourier transform on the channel estimation results on each of the subcarriers to obtain the first time domain response result, the calculation formula of the first time domain response result is as follows: in, is the first time domain response result, w(n) is the noise within the cyclic prefix, L is the length of the cyclic prefix, and h(n) is the time domain response result after the inverse discrete fast Fourier transform of the channel estimation result on the nth subcarrier.

5. The method according to claim 1, characterized in that The step of performing weighted summation on the first time domain response result and the second time domain response result based on a preset weight rule to obtain a target time domain response result comprises: The first time domain response result and the second time domain response result are averaged to obtain a target time domain response result of the channel.

6. The method according to any one of claims 1 to 5, characterized in that: After the step of estimating the channel response based on the actual pilot sequence and the preset reference pilot sequence to obtain the first time domain response result of the channel, the method further includes: The first time domain response result is sent to the second vehicle radio station, so that the second vehicle radio station performs weighted summation on the first time domain response result and the second time domain corresponding result based on a preset weight rule to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1.

7. A vehicle-mounted operation control system, comprising a first vehicle-mounted radio station and a second vehicle-mounted radio station, wherein: The first vehicle-mounted radio station is used to receive a target signal and extract an actual pilot sequence in the target signal; estimating a channel response based on the actual pilot sequence and a preset reference pilot sequence to obtain a first time domain response result of the channel; Detect whether a second time domain response result of the channel sent by the second vehicle-mounted radio station is received, wherein the second time domain response result is obtained by the second vehicle-mounted radio station receiving the target signal, extracting the actual pilot sequence in the target signal, and calculating based on the actual pilot sequence and the reference pilot sequence; when the second time domain response result of the channel sent by the second vehicle-mounted radio station is received, based on a preset weight rule, weighted summing the first time domain response result and the second time domain corresponding result is obtained to obtain a target time domain response result, wherein the sum of the first weight corresponding to the first time domain response result and the second weight corresponding to the second time domain response result is 1; converting the target time domain response result from the time domain to the frequency domain to obtain a downlink channel estimation result based on the frequency domain; The second vehicle-mounted radio station is used to receive the target signal, extract the actual pilot sequence in the target signal, calculate the second time domain response result based on the actual pilot sequence and the reference pilot sequence, and send the second time domain response result to the first vehicle-mounted radio station.

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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