CN113306598B - Rail transit vehicle-vehicle communication method based on space-time division multiple access - Google Patents

Abstract

The invention discloses a rail transit vehicle-vehicle communication method based on space-time division multiple access, which comprises the steps of firstly determining the position and speed information of a train through a transponder, a speed sensor and a wireless positioning device, dividing a same-frequency channel for train communication into a plurality of time slots through a time division multiplexing mode, numbering the train by combining the relationship between the position of the train and a kilometer post, wherein each train occupies one time slot, and each time slot cyclically occurs in time after the time slot occupied by all trains is finished, so that the same-frequency interference between the trains is avoided and the direct communication between the trains can be realized within a certain distance range. By multiplexing and combining the time slots, the utilization rate of the time slots is increased, and frequency resources can be greatly saved. Meanwhile, the method can be combined with the current CBTC system, and provides a more favorable guarantee for the safe operation of the train under the condition that the system has faults or manual operation errors.

Description

A vehicle-to-vehicle communication method for rail transit based on space-time division multiple access

technical field

The invention relates to the technical field of vehicle-to-vehicle communication, in particular to a rail transit vehicle-to-vehicle communication method based on space-time division multiple access.

Background technique

In the traditional communication-based train operation control system (CBTC system), in order to prevent train conflicts and achieve high-density mobile block train tracking intervals on the basis of ensuring safety, it relies on safe and efficient mobile authorization generation technology and a continuous Reasonable application of the train safety braking model based on the formula speed-distance curve. At present, the train operation control system based on communication does not rely on the track circuit to detect the position of the train and transmit information to the on-board equipment, but uses communication technology to realize the speed of information exchange through on-board equipment, on-site communication equipment and the station or train operation control center. control. This kind of control system can realize two-way communication between vehicle and ground. Since there is no pre-set block area, and the fixed block area is not used as the smallest unit of train tracking, the system has greater application flexibility and smaller size than the mobile block system. Therefore, it has a greater ability to adjust the operation.

However, in the case of CBTC system failure or human error, train rear-end accidents may still occur. For example, when the interlock fails, the train in the fault section will first be fault-oriented and take emergency braking to stop. However, in order to ensure operational efficiency, the train will cut off the ATP system, adopt manual driving mode, and use the telephone blocking method to organize traffic. At this time, if the driver or operator does not operate properly, there is a risk of the train colliding with the vehicle in front. Once on Line 10 of the Shanghai Metro, due to the failure of the signal equipment, the subway was switched to a manual telephone block organization. The train was in the ATP system and the manual visual driving mode was removed. Due to the illegal operation of the dispatcher and the station attendant, the train and the front Car rear-end. According to statistics, from 2014 to 2018, a total of 405 failures of various types occurred in the Beijing subway, and nearly half of the failures were caused by the failure of signal equipment. Frequent signal failure accidents have caused great personal losses and had a bad impact on society, which puts forward higher requirements for the emergency protection capabilities of urban rail transit. In the signal failure scenario, how to obtain the position information of the vehicle in front is the key to the research on train collision avoidance. Therefore, a method of direct communication between vehicles is needed to ensure the safe operation of trains.

At present, the existing train operation control system based on vehicle-to-vehicle communication, in essence, only simplifies the trackside equipment. Plan to realize functions such as independent planning of the running route of the train, identification of the vehicle in front, and independent calculation of mobile authorization, but it has not achieved direct communication between vehicles in the true sense.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention provides a rail transit vehicle-to-vehicle communication method based on space-time division multiple access, which relates to preventing accidents in the case of existing CBTC system failure or human error in rail transit. A technology that realizes direct communication between short-distance vehicles.

In order to achieve the above-mentioned purpose of the invention, the technical solution adopted to solve the technical problems is as follows:

A rail transit vehicle-to-vehicle communication method based on space-time division multiple access, comprising:

Step S1: Determine the position and speed information of the train through the transponder, speed sensor, and wireless positioning device;

Step S2: Divide the train communication frequency points into several time slots by means of time division multiplexing;

Step S3: Combining the relationship between the position of the train and the mileage mark, number the train, and each train occupies one of the time slots;

Step S4: reusing time slots to further improve channel utilization;

Step S5: After all the trains occupy the time slots, each time slot occurs cyclically in time;

Step S6: Realize direct communication between vehicles within a certain distance range.

Further, the step S1 includes:

The train positioning method mainly obtains the current position and speed information of the train through the balise on the rail transit line, the speed sensor on the wheel and rail, and the wireless positioning equipment; Provide the current corresponding position information; the speed sensor adopts a pulse speed sensor, uses the circumference of the wheel as a ruler to measure the traveling distance of the train, and calculates the running speed of the train according to the measured train traveling distance.

Further, the step S2 includes:

Step S201: Determine the number of trains on the line through the train schedule;

Step S202: N trains will be running on the line. In order to prevent the same-frequency interference of communication between vehicles, time-division multiplexing is adopted to divide the communication frequency into several time slots;

Step S203: It is stipulated that the maximum wireless communication distance on the main line is R, the minimum train length is L, the minimum train spacing is P, and the number of specific time slots is W, then W=2*R/(L+P ).

Further, the step S3 includes:

Step S301: Taking the mile mark corresponding to the frontmost train on the entire line as a reference, the frontmost train is marked as train 1, and the trains closest to this mileage mark are preferentially numbered, followed by train 2, train 3...train N ;

Step S302: According to the numbering sequence of the trains, each train randomly sends occupancy applications. When there is no conflict, the trains occupy the time slots sequentially according to the time of sending. trains are randomly delayed for a certain period of time at the same time, and the occupancy application is resent; if there is a conflict with other trains again, the resend will be delayed until the occupancy is successful, and finally all trains on the line will successfully occupy all time slots.

Further, the step S4 includes:

Divide the divided time slots into two groups on average, the first K vehicles occupy the first M/2 time slots according to the occupancy rules, the K+1 to 2K vehicles occupy the last M/2 time slots, and the 2K+1 to If the distance between the 3K trains and the previous K trains is too far, they can share the previous M/2 time slots with the previous K trains, and the follow-up trains will be analogized successively. The rules for occupying the time slots are the same as those described in step S302, so as to achieve the time slots of multiplexing.

Further, the step S5 includes:

It is stipulated that each time δms is occupied, there are X time slots in total, so the period of one cycle is δXms. After all trains occupy their respective time slots, each time slot occurs cyclically in time.

Further, the step S6 includes:

Step S601: The distance between the two vehicles is defined as D, the position coordinate of the front vehicle is T1, and the position coordinate of the rear vehicle is T2, so D=T1-T2;

Step S602: Since the wireless communication signal is attenuated in the air, in order to ensure the quality of the vehicle-to-vehicle communication, when D<M meters, the value of M is related to the attenuation degree of the wireless signal in the air, and the vehicle-to-vehicle When the train distance is close enough, the direct communication between trains can make the train run more safely and reliably.

Compared with the prior art, the present invention has the following advantages and positive effects due to the adoption of the above technical solutions:

The rail transit provided by the present invention is based on the space-time-division multiple access rail transit vehicle-to-vehicle communication method. The position information of the train is determined through a transponder, a speed sensor and a wireless positioning device. In the way of multiplexing, the frequency points of train communication are divided into several time slots, combined with the relationship between the position of the train and the mileage mark, the trains are numbered, and each train occupies one of the time slots. In order to make the utilization rate of the time slots higher, the present invention According to the limited propagation distance of wireless signals, the time slots will be reused. When all the trains occupy the time slots, each time slot will occur cyclically in time, so that within a certain distance range, the communication between trains and trains will be realized. direct communication. This method is not only simple and practical to implement, but also greatly saves frequency resources. At the same time, this method can be combined with the current CBTC system to provide a more favorable guarantee for the safe operation of the train in the case of system failure or human error.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings that need to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to these drawings without creative work. In the attached picture:

Fig. 1 is a schematic flow chart of a method for rail transit vehicle-to-vehicle communication based on space-time division multiple access in the present invention;

Fig. 2 is how each train takes up the time slot schematic diagram in turn;

Fig. 3 is a schematic diagram of timeslot multiplexing.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described and discussed below in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all examples. Based on the present invention All other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Figure 1 is a schematic flow chart of a rail transit vehicle-to-vehicle communication method based on space-time division multiple access provided by an embodiment of the present invention; as shown in Figure 1, this embodiment discloses a rail transit vehicle-to-vehicle communication method based on space-time division multiple access Communication methods, including:

Step S1: Determine the position and speed information of the train through the transponder, speed sensor, and wireless positioning device;

Specifically, in the actual application of rail transit, the current train positioning method mainly obtains the current position and speed information of the train through the transponder on the rail transit line, the speed sensor on the wheel and rail, and the wireless positioning device. Among them, the transponder, as a point-type data transmission device with high speed and large amount of information, can provide the current corresponding position information for the train. Speed sensor Pulse speed sensor is generally used in the current rail transit, that is, the circumference of the wheel is used as a "ruler" to measure the running distance of the train, and the running speed of the train is calculated according to the measured running distance of the train. In order to prevent the influence of wheel idling and skidding on the axle speed sensor, a Doppler radar speed sensor can be installed on the train to accurately measure the train speed and position.

Step S2: Divide the train communication frequency points into several time slots by means of time division multiplexing;

Specifically, the step S2 includes:

Step S201: Determine the number of trains on the line through the train schedule;

Step S202: If N trains will be running on the line, in order to prevent the same-frequency interference of communication between vehicles, time-division multiplexing is used to divide the communication frequency into several time slots;

Step S203: specify that the maximum wireless communication distance on the main line is R (2km≤R≤3km), the minimum train length is L (200m≤L≤300m), the minimum train spacing is P, and the number of specific time slots is W, then W=2*R/(L+P).

Exemplarily, the maximum wireless communication distance is 2km, the minimum train length is 200m, and the minimum train distance is 200m, then the number of divided time slots at this time is 10.

Step S3: Combining the relationship between the position of the train and the mileage mark, number the train, and each train occupies one of the time slots;

Specifically, the step S3 includes:

Step S301: Taking the mile mark corresponding to the frontmost train on the entire line as a reference, the frontmost train is marked as train 1, and the trains closest to this mileage mark are preferentially numbered, followed by train 2, train 3...train N ;

Step S302: According to the numbering sequence of the trains, each train randomly sends occupancy applications. When there is no conflict, the trains occupy the time slots sequentially according to the time of sending. trains are randomly delayed for a certain period of time at the same time, and the occupancy application is resent; if there is a conflict with other trains again, the resend will be delayed until the occupancy is successful, and finally all trains on the line will successfully occupy all time slots.

Exemplarily, taking the mile mark corresponding to the frontmost train on the entire line as a reference, the frontmost train is marked as train 1, and the priority numbers of the trains closest to this mileage mark are train 2, train 3... train N, select five trains in the example, as shown in Figure 2, according to the numbering sequence of the trains, each train randomly sends occupancy applications, when there is no conflict, the trains occupy the time slots successively according to the time of sending, as shown in Figure 2 1 and train 4; when two trains send occupancy applications at the same time, a conflict occurs at this time, as shown in Figure 2, train 2 and train 3, then the two trains are randomly delayed for a certain period of time at the same time, and the occupancy application is resent; If a conflict occurs, such as train 3 and train 5, the transmission will be delayed until the occupancy succeeds. Eventually all trains on the line will successfully occupy all time slots.

Step S4: reusing time slots to further improve channel utilization;

Specifically, the step S4 includes:

Due to the limited propagation distance of wireless signals, in order to save frequency resources, we can reuse time slots to further improve channel utilization. As an example, divide the divided time slots into two groups on average. The first K vehicles occupy the first M/2 time slots according to the occupancy rules, the K+1 to 2K vehicles occupy the last M/2 time slots, and the first K vehicles occupy the last M/2 time slots. 2K+1 to 3K trains are too far away from the previous K trains, then they can share the previous M/2 time slots with the previous K trains, and the follow-up trains can be deduced by analogy. The rules for occupying the time slots are the same as those described in step S302. So as to achieve multiplexing of time slots.

Exemplarily, as shown in FIG. 3, according to step S2, the communication frequency points are divided into 10 time slots in total, and these 10 time slots are now divided into groups of 5 Two groups, the first 5 trains on the line occupy the first group of time slots according to the occupancy rules, the 6th to 10th trains occupy the second group of time slots, the 11th to 15th trains, due to the gap between the first 5 trains The range of wireless communication is limited, and there will be no conflict or interference when sending communication information with the first five vehicles at the same time, then the first group of time slots can be reoccupied; similarly, the 16th to 20th vehicles reoccupy the second group of time slots, and subsequent And so on for trains to maximize channel utilization.

Step S5: After all the trains occupy the time slots, each time slot occurs cyclically in time;

Exemplarily, it is stipulated that each time δms is occupied, there are X time slots in total, so the period of one cycle is δXms. After all the trains occupy their respective time slots, each time slot occurs cyclically in time, that is, each train is in its respective The information is sent cyclically in the time slot.

Step S6: Realize direct communication between vehicles within a certain distance range.

Specifically, the step S6 includes:

Step S601: The distance between the two vehicles is defined as D, the position coordinate of the front vehicle is T1, and the position coordinate of the rear vehicle is T2, so D=T1-T2;

Step S602: Due to the attenuation of wireless communication signals in the air, in order to ensure the quality of vehicle-to-vehicle communication, it is stipulated that D<M meters (the value of M can be obtained by matching the corresponding modification factor through theoretical calculation, or can be obtained from an empirical model) , can establish direct communication between trains, when the distance between trains is close enough, the direct communication between trains can make the train run more safely and reliably.

In summary, the technical scheme provided by the present invention can be seen that the present invention divides the communication channel of the train into several time slots by utilizing the basic principle of time division multiplexing, and in combination with the position information of the train, according to the conflict detection mechanism designed in the present invention, Each train occupies one of the time slots, which effectively solves the problem of co-frequency interference between trains and vehicles. At the same time, in order to make the utilization rate of the time slots higher, the invention also groups the time slots to realize the multiplexing of the time slots. Make channel utilization higher. After the train successfully occupies the time slot, each time slot occurs cyclically in time, within a certain distance range, the direct communication between the trains can be realized, thus providing another favorable way for the safe operation of the train Assure.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for relevant parts, please refer to part of the description of the method embodiment. The device and system embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is It can be located in one place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those skilled in the art can understand and implement the above description of the specific embodiments of the present invention without any creative effort.

It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (5)

1. A rail transit vehicle-vehicle communication method based on space-time division multiple access is characterized by comprising the following steps:

step S1: determining the position and speed information of the train through the transponder, the speed sensor and the wireless positioning equipment;

step S2: dividing the frequency point of train communication into a plurality of time slots in a time division multiplexing mode;

and step S3: the method comprises the steps of numbering trains by combining the relationship between the positions of the trains and kilometers, wherein each train occupies one time slot;

the step S3 includes:

step S301: the kilometer post corresponding to the most front train on the whole line is taken as a reference, the most front train is marked as a train 1, and the trains close to the kilometer post are sequentially numbered as a train 2 and a train 3 … … train N;

step S302: according to the numbering sequence of the trains, each train randomly sends an occupation application, when no conflict exists, the trains occupy time slots in sequence according to the sending time, when two trains send the occupation applications simultaneously, the conflict is generated at the moment, the two trains simultaneously and randomly delay for a certain time length, and the occupation applications are sent again; if the train conflicts with other trains again, delaying the retransmission until the train is successfully occupied, and finally successfully occupying all time slots by all trains on the line;

and step S4: the time slot is repeatedly utilized, and the utilization rate of the channel is further improved;

the step S4 includes:

averagely dividing the number of the divided time slots into two groups, wherein the front K vehicles occupy the front M/2 time slots according to an occupation rule, the K +1 to 2K vehicles occupy the rear M/2 time slots, and the 2K +1 to 3K trains are far away from the front K trains, so that the front M/2 time slots can be occupied by the front K vehicles together, the subsequent trains are analogized in sequence, and the rule of occupying the time slots is the same as that in the step S302, so that the time slot multiplexing is realized;

step S5: after all trains occupy the time slot, each time slot occurs cyclically in time;

step S6: within a certain distance range, direct communication between vehicles is realized.

2. The rail transit vehicle-vehicle communication method based on space-time division multiple access according to claim 1, wherein the step S1 comprises:

the train positioning mode mainly comprises the steps that the current position and speed information of a train is obtained through a transponder on a rail transit line, a speed sensor on a wheel rail and wireless positioning equipment; the responder is used as a high-speed point type data transmission device with large information quantity and provides current corresponding position information for the train; the speed sensor adopts a pulse speed measuring sensor, the circumference of a wheel is used as a ruler to measure the running distance of the train, and the running speed of the train is measured according to the measured running distance of the train.

3. The rail transit vehicle-vehicle communication method based on space-time division multiple access according to claim 1, wherein the step S2 comprises:

step S201: determining the number of trains on the line through a train operation timetable;

step S202: n trains are to run on a line, and in order to prevent the same frequency interference of communication between the trains, a time division multiplexing method is adopted to divide a communication frequency point into a plurality of time slots;

step S203: when the maximum wireless communication distance on the main line is defined as R, the minimum train length is defined as L, the minimum train interval is defined as P, and the number of specific time slots is defined as W, W = 2*R/(L + P).

4. The rail transit vehicle-vehicle communication method based on space-time division multiple access according to claim 1, wherein the step S5 comprises:

it is specified that each time occupies δ ms, X time slots are provided, so the cycle time period is δ Xms, and when all trains occupy their respective time slots, the time slots cyclically occur in time.

5. The rail transit vehicle-vehicle communication method based on space-time division multiple access according to claim 1, wherein the step S6 comprises:

step S601: defining the distance between two vehicles as D, the position coordinate of the front vehicle as T1 and the position coordinate of the rear vehicle as T2, so that D = T1-T2;

step S602: because the wireless communication signal is propagated in the air and attenuated, when D is regulated to be less than M meters in order to ensure the communication quality between the train and the workshop, the value of M is related to the attenuation degree of the wireless signal in the air, the direct communication between the train and the train can be established, and when the train distance is close enough, the direct communication between the train and the train can ensure that the train runs more safely and reliably.

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