CN101774391B - Topology control method for wireless sensing network of railway traffic - Google Patents

Abstract

The invention discloses a method for realizing a wireless sensor network for railway traffic. First, the area along the railway that needs to transmit train running information is divided into several sections, and a converging node is set up in each section; segment is further divided into M area blocks with length l; calculate the number n _i of wireless nodes that need to be arranged in each area block, and then calculate the distance d _i of wireless nodes in each area block, d _i =1 /n _i ; arrange the wireless nodes evenly in the middle of each area block according to the distance d _i , and assign an ID number to each wireless node in sequence; The sink node in the segment communicates with the train safety operation control center. The present invention adopts the method of distributing points in blocks to determine the optimal deployment distance of the wireless nodes in the area blocks. The wireless nodes adopt the work-sleep rotation mechanism, which can effectively improve the lifetime of the network and ensure the safety of trains.

Description

A topology control method for wireless sensor network used in railway traffic

technical field

The invention relates to the field of wireless sensor networks, in particular to a topology control method for wireless sensor networks used in railway traffic. the

Background technique

Wireless sensor network is a brand-new development direction in the field of information science, and it is also the result of crossover between emerging disciplines and traditional disciplines. It has evolved with technological advances in areas such as sensors, wireless communications, embedded computing, distributed processing, and microelectronics. At present, the wireless sensor network has played an important role in the fields of environmental monitoring, intelligent transportation, medical monitoring, urban management, logistics management and construction. the

The use of wireless sensor networks in railway traffic is of great significance to the safety of train operation and the transmission of various train driving information along the railway. For example, for the safety of train operation, it often happens that the speed limit is carried out during the running of the train. At present, my country's railway management department has two ways to limit the speed of trains: inherent speed limit and temporary speed limit. For the inherent speed limit of the road section, the speed limit can be realized by pre-setting the vehicle-mounted LKJ device. This method reduces the influence of human factors and improves driving safety; When driving at a high speed, the driving information stored in the vehicle-mounted LKJ device cannot be updated in time, and the temporary speed limit is notified to the driver by placing a temporary speed limit sign, which is greatly affected by human and external factors, and problems such as missed recognition and false recognition are prone to occur, resulting in occurrence of security incidents. the

In this case, if there are sensor wireless nodes along the railway, for the area where speed limit is required, the train operation control center issues speed limit commands to the wireless nodes in the area, and the speed limit commands are arranged one by one via the wireless nodes along the railway. Jump to the destination wireless node, and the passing train can read the speed limit information through the reader on the train, which not only reduces the trouble of manual configuration, but also can accurately and quickly send the speed limit command to the It improves the safety of train operation and is more suitable for temporary speed limit. the

However, if the existing wireless sensor network is copied and applied to railway traffic, that is, each wireless node is randomly installed in the section that needs speed limit, each wireless node is always in working state, and because in practical application, Only when the train is approaching the road section, it is necessary to actually use the broadcast information of the wireless node, which makes the wireless node in a state of idle resources in most cases, without considering the service life of different wireless nodes at different locations and The problem of resource optimization makes it often necessary to replace wireless nodes that are faulty or exhausted. As a result, train running information such as train speed limit information cannot be released in time, and the lifetime of the network is greatly limited, which seriously affects the safety of train driving. Therefore, an effective topology control method is needed to prolong the lifetime of the network.

Contents of the invention

The purpose of the present invention is to overcome the problems of the above-mentioned prior art and provide a topology control method for a wireless sensor network used in railway traffic. The present invention adopts the method of distributing points in blocks to divide the entire railway area into sections , the section is divided into area blocks with different wireless node densities, and according to the predicted energy consumption rate of wireless nodes in each area block, the optimal deployment distance of wireless nodes in the area block is determined. At the same time, the wireless nodes of the present invention adopt a work-sleep rotation mechanism, and a working node is set every distance L in the section, and other wireless nodes are in a dormant state. Therefore, the wireless sensor network implemented in the present invention for railway traffic can effectively Improve the life span of the network, ensure the timely release of train driving information such as train speed limit information and the safety of train driving. the

The purpose of the present invention is achieved through the following technical solutions: a topology control method for the wireless sensor network of railway traffic, specifically as follows:

First, divide the area along the railway that needs to transmit train running information into several sections, and set up a converging node in each section;

According to the total number N of wireless nodes to be arranged in a specific section and the status of the railway, the section is further divided into M area blocks with a length of 1;

According to the inverse proportional relationship between the speed r _i of the total energy consumption of all wireless nodes in each area block and the distance between the area block and the sink node, calculate the number of wireless nodes n _i that need to be arranged in each area block, and then calculate The distance d _i of wireless nodes in each area block, d _i =1/n _i ;

Arrange wireless nodes evenly in the middle of each area block according to the distance d _i , and assign ID numbers to each wireless node in sequence;

Set up a working node every distance L in the section, and other wireless nodes are in a dormant state, and the wireless nodes perform work/sleep state rotation in units of area blocks;

All wireless nodes in the section communicate with the train safety operation control center through the convergence node in the section. the

The convergence node has two communication modes: one is a short-distance wireless communication mode, which is used to communicate with wireless nodes in the section; the other is a long-distance wireless communication or wired communication mode, which is used to connect to external network. All wireless nodes in the same section transmit information to the sink node, and the sink node is then connected to the external network to exchange information with the train safety operation control center. the

In order to optimize the communication between the convergence node and all wireless nodes in the segment, the convergence node is set at the midpoint of the segment to which it belongs. the

After the configuration of the wireless nodes is completed, not all the wireless nodes work at the same time, but are divided into two states of working and dormancy to prolong the life of the non-electric nodes. the

When the network is initialized, all wireless nodes are in the working state. Since the distance between each hop is more uniform during the information forwarding process, the total energy consumed by the wireless nodes is less, so it can be calculated according to this principle. The optimal distance L between working nodes. A working node is set every distance L in the section, and other wireless nodes are in a dormant state, and the method is specifically as follows:

Set the wireless node whose ID number is 1 in the section as the working node first, and then set the next working node every distance L, and other wireless nodes between the working nodes will enter the dormant state. the

When setting a working node, after a working node is selected, there may not be a wireless node at a distance of L from the working node. At this time, the wireless node whose distance from the working node is closest to L is selected as the next working node. the

The optimal distance L is the d value that makes (ad ^α +b)gl/d the smallest result, wherein d is the distance between each hop, b is the energy consumed by a single wireless received signal, and α is the path fading coefficient , a is the transmission coefficient of the wireless node transmitter.

The work/sleep state rotation mechanism for the wireless node to perform work/sleep state rotation in units of area blocks is:

After setting up the working nodes and sleeping nodes, the internal timers of all wireless nodes in the segment start counting at the same time;

The working node is responsible for forwarding the information transmitted by the last hop working node in the section to which it belongs, while the dormant wireless node turns off the receiver and transmitter, waiting for the arrival of its own working time;

A rotation of working nodes is performed every time T, and the previous round of working nodes will select the next wireless node in the area block as a new round of working nodes, and it will enter a dormant state. the

After working for a period of T, the working node will enter the dormant state, but it will not enter the dormant state immediately, but will be in the dormant state for a time length of t, t is less than T, generally take t=T/100, at this time Carry out the rotation of the working node, the rotation is based on the area block, and the working node with the ID number i in the dormant state will send a rotation message, and prepare to select the wireless node with the ID number i+1 as the next working node. Wireless node i+1 wakes up within the time period t, and will immediately receive the rotation information of wireless node i, and return confirmation information to wireless node i, and wireless node i will enter the dormant state after the t period ends, i The +1 wireless node becomes a new working node, and at the same time sends a message to the nearby wireless nodes that have just woken up from sleep, telling them to re-enter the sleep state; if the i wireless node cannot receive the i+1 number within the t period If the confirmation message sent by the wireless node wakes up, the wireless node i will still be the working node in the next T period. the

If wireless node i continues to work as a working node without receiving the confirmation sent by node i+1 for 3 consecutive T periods, it is considered that wireless node i+1 is faulty, and wireless node i will The train safety operation control center is notified by the converging node to repair it. Before the i+1 node is repaired, the i node will select the i+2 node as the next working node. the

If the working node i that will enter the dormant state is at the border of the section it belongs to, that is, the working node i is the last working node of one of the boundaries of the section it belongs to, it will forward its rotation information through other working nodes To the other boundary of the section, if the working node i' at the other end of the section is also a working node in the previous round, both the working node i' and the working node i will enter the dormant state in the next T period. the

Advantage and beneficial effect of the present invention relative to above-mentioned prior art are as follows:

(1) The present invention utilizes the method of wireless sensor network, and the train safety operation control center can transmit the train running information to the destination work point through the converging node through the multi-hop network, and the passing train can read the information of this point, the information The release process is all completed by the wireless sensor network, without manual intervention, reducing the difficulty of personnel setting up various notices in harsh environments;

(2) It can quickly issue train driving information, reduce various safety accidents, and improve train driving safety;

(3) The network itself can detect faults by itself. Once a faulty wireless node is found, it will report to the train safety operation control center in time to improve the security of the network;

(4) The wireless node adopts a flexible configuration method and a work-sleep rotation mechanism, which can save the energy consumption of the wireless node and effectively extend the network lifetime. the

Description of drawings

Fig. 1 is the wireless node layout diagram of the wireless sensor network along the railway of the present invention;

Fig. 2 is a schematic diagram of wireless node information transfer of the present invention;

FIG. 3 is a schematic diagram of a work-sleep rotation mechanism of a wireless node. the

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto. the

As shown in Figure 1, a topology control method for wireless sensor network used in railway traffic,

Firstly, the area along the railway line that needs to transmit train running information is divided into several sections, and a converging node is set up at the midpoint of each section. the

The convergence node has two communication modes: one is a short-distance wireless communication mode, which is used to communicate with wireless nodes in the section; the other is a long-distance wireless communication or wired communication mode, which is used to connect to external network. All wireless nodes in this section transmit information to the sink node, and the sink node is connected to the external network to exchange information with the train safety operation control center. the

All wireless nodes in the section communicate with the train safety operation control center through the convergence node in the section. the

The configuration method of the wireless node is as follows:

According to the total number N of wireless nodes to be arranged in the specific section and the railway conditions, the section is further divided into M area blocks with a length of 1; the ID numbers of each area block are 1, 2, ..., m, ... , M-1, M, with the sink node as the center, the density of wireless nodes in the area block decreases as the distance from the sink node increases, and the wireless nodes in the area block are linearly and equidistantly distributed in the area block middle. This is because in the strip network along the railway, the wireless nodes act as the role of information collection and forwarding, and the distribution of wireless nodes is in a strip shape. It can be seen that the closer the wireless node is to the sink node, the more times the information is forwarded. The more energy will be consumed, the faster the energy consumption will be than that far away from the sink node. Therefore, in order to prolong the life of the entire network, the closer to the sink node, the density of its wireless nodes should increase accordingly. the

According to the inverse proportional relationship between the speed ri of the total energy consumed by all wireless nodes in each area block and the distance between the area block and the sink node, that is, the farther away from the sink node, the less the total energy consumed; the closer the distance to the sink node, The more total energy consumed. Therefore, in order to make the energy consumption rate of each node the same, all N wireless nodes will be allocated to each area block according to the above-mentioned proportional relationship of energy consumption, and the number n _i of wireless nodes that need to be arranged in each area block can be calculated, for example , assuming that the section is divided into 5 area blocks, the distance ratio between the five area blocks and the intermediate sink node should be 3:2:1:2:3, and the energy consumption ratio should be 1:2:3: 2:1, assuming that there are a total of 1100 nodes, the number of nodes allocated to each area block should be 100, 200, 300, 200, 100, after calculating _ni , and then calculate the distance between wireless nodes in each area block d _i , d _i =1/n _i .

After the configuration of the wireless nodes is completed, not all the wireless nodes work at the same time, but are divided into two states of working and dormancy to prolong the life of the non-electric nodes. Therefore, a working node is set every distance L in the section, and other wireless nodes are in a dormant state, and the wireless nodes perform work-sleep rotation in units of area blocks. the

When the network is initialized, all the wireless nodes are in the working state. Since the distance between each hop is more uniform during the information forwarding process, the total energy consumed by the wireless nodes is less. the

Moreover, there is the following relationship between the total energy e consumed by signal forwarding between wireless nodes and the distance D of wireless transceiver nodes: e(D)=(aD ^α +b ₁ )+b ₂ , where b ₁ and b ₂ are wireless The energy consumed by the sending and receiving nodes to transmit and receive messages. Find a D value to minimize the energy consumption of the entire network E=e(D)*Length/D (Length is the total length of the network) during a message transfer. This D value is also the distance between each hop of working nodes L, and then set the wireless node whose sequence number is 1 in the segment as the working node first, and then set a working node every distance L later. After a working node is selected, there may be no wireless node at a distance L from the working node. At this time, the wireless node whose distance from the working node is closest to L is selected as the next working node. When information is generated at a certain working node, the information will be transmitted to the sink node hop by hop through its adjacent working nodes, as shown in Figure 2.

The work-sleep rotation mechanism for wireless nodes to perform work-sleep rotation in units of area blocks is:

After setting up the working nodes and sleeping nodes, the internal timers of all wireless nodes in the segment start counting at the same time;

The working node is responsible for forwarding the information transmitted by the last hop working node in the section to which it belongs, while the dormant wireless node turns off the receiver and transmitter, waiting for the arrival of its own working time;

A rotation of working nodes is performed every time T, and the previous round of working nodes will select the next wireless node in the area block as a new round of working nodes, and it will enter a dormant state. the

As shown in Figure 3, the working node will enter the dormant state after working for a period of time T, but it will not enter the dormant state immediately, but will be in the off-sleep state for a time length of t, t is less than T, generally take t= T/100, at this time, the rotation of the working node is to be carried out. The rotation takes the area block as the unit. The working node with the ID number i in the off-dormant state will send a rotation message, and prepare to select the wireless node with the ID number i+1 as the The next working node, if the i+1 wireless node wakes up within the t period, it will immediately receive the rotation information of the i wireless node and return the confirmation information to the i wireless node. After the t period ends, the i wireless node The node will enter the dormant state, and the wireless node i+1 becomes a new working node, and at the same time sends a message to the nearby wireless nodes that have just woken up from dormancy, telling their wireless nodes to re-enter the dormant state; if the wireless node i If the confirmation message sent by wireless node i+1 is not received, wireless node i will still be a working node in the next T period. the

If wireless node i continues to work as a working node without receiving the confirmation sent by node i+1 for 3 consecutive T periods, it is considered that wireless node i+1 is faulty, and wireless node i will The train safety operation control center is notified by the converging node to repair it. Before the i+1 node is repaired, the i node will select the i+2 node as the next working node. the

If the working node i that will enter the dormant state is at the border of the section it belongs to, that is, the working node i is the last working node of one of the boundaries of the section it belongs to, it will forward its rotation information through other working nodes To the other boundary of the section, if the working node i' at the other end of the section is also a working node in the previous round, both the working node i' and the working node i will enter the dormant state in the next T period. the

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention. the

Claims (10)

1. a topology control method that is used for the wireless sense network of railway traffic is characterized in that, and is specific as follows:

The railway area along the line that at first will transmit train travel information is divided into several sections, sets up an aggregation node at each section;

Radio node sum N and rail conditions according to needs in the concrete section are arranged further are divided into M the region unit that length is l again with this section;

Consume the speed r of gross energy according to all radio nodes in each region unit _iWith the proportionate relationship that the distance of this region unit and aggregation node is inversely proportional to, the radio node that calculates the required layout of each region unit is counted n _i, and then calculate the spacing d of radio node spare in each region unit _i, d _i=1/n _i

According to spacing d _iRadio node is evenly arranged in the middle of each region unit, gives each radio node arranged in order ID number;

In section, whenever spacing is provided with a working node from L, and other radio node is in dormant state, and radio node is that unit carries out work/dormant state by turns with the region unit;

All radio nodes all communicate through aggregation node in the section and safe train operation control center in the section.

2. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 1; It is characterized in that: said aggregation node has two kinds of communication patterns: a kind of for the short-distance wireless communication pattern, be used for and the radio node of this section communicates; Another kind of for long distance wireless communication or wire communication pattern, be used to be connected to external network; All communicate information to aggregation node with all radio nodes in the section, aggregation node is connected to external network and safe train operation control center carries out information interchange.

3. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 1 is characterized in that: said aggregation node is arranged on the point midway of its affiliated section.

4. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 1; It is characterized in that: said in section, whenever spacing is provided with a working node from L; Other radio node is in dormant state; Its method is specially: the radio node that is 1 for ID in the section number at first is made as working node, and whenever spacing later on is provided with next working node again from L, and other radio node between the working node then gets into dormant state; After a selected working node, possibly not have radio node in place apart from this working node L place, this moment then this working node of selected distance apart near the radio node of L as next working node.

5. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 1 is characterized in that: said distance L is for making (ad ^α+ b) the minimum d value of gl/d result, wherein d is the distance between each jumping, and b is the energy that single wireless receiving signal is consumed, and α is the path fading coefficient, and a is the emissivity factor of radio node emitter.

6. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 1 is characterized in that: said radio node is that unit carries out work/dormant state mechanism of rotating that work/dormant state rotates and is with the region unit:

After setting working node and dormancy node, all radio node in-to-in time meters pick up counting simultaneously in the section;

The information that a last jumping working node biography was come in the section under working node was responsible for transmitting, the radio node of dormancy is then closed Receiver And Transmitter, waits the arrival of own work-hours;

Per interval T carries out rotating of one action node, and last round of working node will be chosen the working node of the interior next radio node of said region unit as a new round, and himself gets into dormant state.

7. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 6 is characterized in that: working node work behind a period of time T, will get into dormant state; But be not to get into dormancy, but can be in the dormancy state of leaving one's post that time span is t, t is less than T at once; To carry out this moment working node by turns, be unit with the region unit by turns, be in ID number of the dormancy state of leaving one's post and send rotation information for the meeting of the working node of i; Prepare to select is for ID number that the radio node of i+1 is as next working node; If t in the time period i+1 radio node revive, then at once can receive the rotation information of i radio node, and return confirmation and give the i radio node; The i radio node can get into dormant state behind the t end cycle; The i+1 radio node becomes new working node, sends information near the radio node of just having revived from dormancy simultaneously, informs that its radio node gets into dormant state again; If t in the cycle i radio node can not receive the affirmation information that the i+1 radio node is revived and sent out, the i radio node still is a working node in the then next T cycle.

8. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 7; It is characterized in that: if continuous 3 T cycles of i radio node all revive under the situation of the affirmation sent out can not receive the i+1 node; Continuation is as working node; Think that then the i+1 radio node breaks down; The i radio node will keep in repair it through aggregation node train notified safe operation control center, and before the reparation of i+1 node, it is next working node that the i node will be chosen the i+2 node.

9. according to claim 7 or 8 described a kind of topology control methods that are used for the wireless sense network of railway traffic; It is characterized in that: if will get into the boundary position that the i working node of dormant state is in affiliated section; Just the i working node is last working node on a wherein border of affiliated section; Then it will transmit its rotation information another border to section through other working node; If be in section the other end i ' number working node last round of also be working node, then the next T of i ' number working node and i working node gets into dormant state in the cycle.

10. a kind of topology control method that is used for the wireless sense network of railway traffic according to claim 7 is characterized in that: said t specifically gets t=T/100 less than T.

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