CN108449199A - A multi-stage multi-service formation wireless communication network reliability assessment method - Google Patents

Abstract

The present invention provide a kind of multistage, formation cordless communication network under multi-service mission profile reliability estimation method, steps are as follows：One：Calculate the Packet Error Ratio of each business；Two：Packet arrives and departs from rate on each node of each business of each stage in analysis task section；Three：Effective arrival rate of packet on calculating task section each stage each node；Four：The parameter of time delay distribution on calculating task section each stage each node；Five：Calculate the transmission reliability of each business；Six：Calculating task reliability；Invention achieves the purposes that quantitative analysis is carried out to the reliability level of the formation cordless communication network under multistage, multi-service mission profile, solves the problems, such as the reliability assessment of formation cordless communication network, it ensure that analytic process science, reasonable and closing to reality situation, reliability assessment result has credibility, simultaneously, institute's extracting method calculates simply, and engineers and technicians is facilitated to use, and has stronger application value.

Description

A multi-stage multi-service formation wireless communication network reliability assessment method

technical field

The present invention proposes a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage, multi-service task profile reliability evaluation method for formation wireless communication networks, which is oriented to formation wireless communication network reliability analysis Considering the actual needs, communication characteristics and transmission mechanism, using technical means such as queuing theory and queuing network theory, the reliability evaluation problem of formation wireless communication network is solved when there are multi-stages and multi-services in the mission profile, which is applicable to Performance analysis and reliability evaluation of wireless communication networks and other related technical fields.

Background technique

A highly reliable formation wireless communication network is one of the basic elements to achieve combat effectiveness and ensure the smooth completion of missions. Evaluating the reliability level of formation wireless communication network can provide a basis for rational deployment of tasks and allocation of resources.

Queuing theory is a commonly used theoretical analysis method in the performance research of wireless communication systems. The related queuing model can describe the information transmission behavior of a single communication node, but queuing theory is only applicable to the reliability analysis of a single communication node, and cannot be directly used in the network level. reliability analysis. Based on the consideration of the actual needs, communication characteristics and transmission mechanism, the formation wireless communication network usually has the following important characteristics. First of all, according to the actual mission requirements, there are usually multiple stages in the task profile of the formation wireless communication network, and there may be multiple services in each stage; secondly, due to the use of wireless communication means, the phenomenon of packet loss and bit error ubiquitous; when packet loss or bit error occurs, the retransmission strategy is currently the simplest and most effective compensation measure; finally, under the multi-hop transmission mechanism, each communication node can be used as a communication node for receiving or sending information. The terminal can also be used as a relay node. In view of the above complex situation, there is no corresponding reliability evaluation method at this stage.

Therefore, the present invention proposes a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage multi-service mission profile reliability evaluation method for formation wireless communication networks.

Contents of the invention

(1) purpose of the present invention:

The present invention aims at the reliability problem of the formation wireless communication network, considers the multi-stage and multi-service situation in the task profile, comprehensively analyzes the influence of actual needs, communication characteristics and transmission mechanism on the reliability of the formation wireless communication network, and uses queuing theory and queuing network Based on theoretical and other technical means, a multi-stage multi-service formation wireless communication network reliability evaluation method is proposed, that is, a multi-stage, multi-service mission profile reliability evaluation method for formation wireless communication network, which is the basis for the formation wireless communication network. Reliability analysis provides a theoretical basis.

(2) Technical solution:

The present invention provides a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage multi-service task profile under the formation wireless communication network reliability evaluation method, the specific implementation steps are as follows:

Step 1: Calculate the packet error rate of each service:

Since communication equipment usually has a certain error correction capability, only when the error rate in the information packet exceeds the error correction capability of the communication equipment, the information packet cannot be received correctly; based on the above understanding, "error packet" is defined as the error rate Information packets greater than or equal to the specified threshold, and define "packet error rate" as the probability of generating error packets;

Assume that for each service, the standard length of the information packet is the same, which is recorded as L bits; the bit error rate is the same, which is recorded as p _{bit error} ; the threshold value of the bit error ratio is the same, which is recorded as K; then, the packet error rate p _{error packet} can be obtained by the following formula calculation

In the formula: N _{error bit} is the number of bit error, Indicates rounding up operation;

Step 2: Analyze the arrival and departure rate of information packets on each node of each service and each stage in the mission profile:

Any communication node (referred to as a node) in the formation wireless communication network can be used not only as a sending or receiving terminal, but also as a relay node. Situation; assuming that when a receiving node (receiving terminal or relay node) does not receive a certain information packet, that is, when a packet loss occurs, or receives an information packet, but it is found to be an error packet after processing, it will immediately request the upper node to re- Send the information packet, the upper node will immediately retransmit the information packet, and the time consumed from requesting retransmission to executing retransmission is small enough to be ignored;

There are four categories of sources of pending packets or "arriving packets" at a node:

1) As a packet generated by the sending terminal:

For business j, if node i is a sending terminal, record the rate at which it generates information packets as λ ^(j) ;

2) Receive the information packet sent by the upper node:

For service j, if node i is a relay node or a receiving terminal, record the rate at which the superior node completes information processing as And the packet loss rate of each service is the same, which is recorded as p _{packet loss} ; due to the existence of error packets, only the information packets with a ratio of 1-p _{error packets} are correct and can be sent to node i; due to packet loss, the information packets sent to node i Only information packets with a ratio of 1-p _{packet loss} can be received; therefore, the arrival rate of information packets sent by the superior node is

3) Information packets that are required to be retransmitted by lower-level nodes due to packet loss:

For business j, if node i is a relay node or a sending terminal, record the rate at which node i completes information processing as For the lower-level nodes, the packet loss rate is found to be Since the lower-level node will immediately request retransmission when it finds packet loss, and the time consumed from requesting retransmission to executing retransmission is negligible, so the rate at which node i is requested to retransmit due to packet loss is equal to the rate at which the lower-level node finds packet loss;

4) Information packets that are required to be retransmitted by lower-level nodes due to error packets:

For service j, if node i is a relay node or a sending terminal, write down the rate at which the secondary node completes information processing as (If the subordinate node is the receiving terminal of service j, Ω is empty, ie Otherwise, Ω is the next-level node); the lower-level node will find out whether it is an error packet after processing the received information packet, so the rate of finding the error packet is Since the lower-level node will immediately request retransmission when it finds an error packet, and the time consumed from requesting retransmission to executing the retransmission is negligible, the rate at which node i is required to retransmit due to an error packet is equal to the rate at which the lower-level node finds an error packet rate;

Based on the above analysis, the arrival rate of information packets from each source is summarized in Table 1;

Table 1 Arrival rate of information packets on nodes

On the other hand, packets that are processed on a node, or "leaving packets," go in two ways:

1) Complete business as a receiving terminal:

For business j, if node i is the receiving terminal, record the rate at which it completes information processing as

2) After processing the information packet, continue to send the correct information packet to the lower-level node:

For service j, if node i is a relay node or a sending terminal, the rate at which it completes information processing is

Based on the above analysis, the departure rate of the information packets for each destination is summarized in Table 2;

Table 2 Departure rate of packets on nodes

According to the queuing network theory, when it is in a steady state, each node is in a steady state for the processing of each business; that is, for the process of node i executing business j, the sum of the arrival rates of information packets from all sources is equal to all the sum of the departure rates of the destined packets;

Table 1 and Table 2 can enumerate the arrival rate of information packets from all sources of node i performing business j, and the departure rate of all destination information packets, and establish an equation; then, establish an equation for each service of each node Formula, simultaneous equations, can solve all unknown parameters;

Step 3: Calculate the effective arrival rate of packets on each node in each phase of the mission profile:

According to the queuing network theory, it can be known that the "effective arrival rate" of information packets on a node is the sum of the arrival rates of information packets from all sources of all services undertaken by a node, and its value is the same as that of the information packets of all destinations of all services undertaken by it. The sum of the departure rates of is equal; therefore, in the task profile phase w, the effective arrival rate λ _i ^w of the information packet of node i can be calculated by the following formula

In the formula: λ ^(j) is the rate at which node i generates information packets if it is the sending terminal of service j; p _{packet loss} is the packet loss rate; p _{error packet} is the packet error rate; If node i is the relay node of service j, the rate at which its superior node completes information processing; is the rate at which node i completes information processing if it is a relay node or sending terminal of service j; If node i is the relay node or sending terminal of service j, the rate at which its subordinate nodes complete information processing; is the rate at which node i completes information processing if it is the receiving terminal of service j;

Step 4: Calculate the parameters of the delay distribution on each node in each stage of the task profile:

Assuming that the packet processing rate of all nodes is the same, denoted as μ; according to the queuing theory, for node i in the task profile stage w, when μ>λ _i ^w and the buffer area of the communication device is large enough, the node i The time delay T _i obeys the exponential distribution of the reciprocal of the scale parameter is μ _i ^w = μ-λ _i ^w ;

Step 5: Calculate the transmission reliability of each service:

For a certain service, define "transmission reliability" as the probability that the total delay of information packet transmission is less than or equal to the specified delay threshold;

Assume that the business j in the mission profile phase w is completed by nodes 1, 2, ..., node i, ..., node n, and the delivery order of information packets is consistent with the numbering order of nodes; For business j, the total delay T ^(j) can be expressed as Since T _i obeys the parameter as Exponential distribution of T ^(j) cumulative distribution function Expressed as

In the formula: t is time; n is the total number of nodes participating in business j in task profile phase w; μ _i ^w is the parameter of delay distribution on node i in task profile phase w, that is, the reciprocal of the scale parameter; μ _k ^w is The parameter of the delay distribution on node k in the task profile stage w, that is, the reciprocal of the scale parameter;

For the delay threshold Y _j of service j in the task profile phase w, the transmission reliability R( ^j) can be calculated by the following formula

In the formula: n is the total number of nodes participating in the service j in the task profile stage w; μ _i ^w is the parameter of the delay distribution on node i in the task profile stage w, that is, the reciprocal of the scale parameter; is the parameter of the delay distribution on node k in the mission profile stage w, that is, the reciprocal of the scale parameter;

There is a problem in the calculation of the analytical expression of the above transmission reliability: when the parameters of the delay distribution on several nodes are similar, the use of computer calculations will produce large errors and lead to unreasonable results; therefore, a calculation method is proposed at the same time Monte Carlo simulation method of transmission reliability, which can be used as a general method for calculating transmission reliability;

For service j in mission profile phase w, the Monte Carlo simulation method of transmission reliability is as follows:

1) The number of times the total initialization delay is less than or equal to the threshold Y _j , let N _T =0;

2) From the parameter as Draw a random number t _i from the exponential distribution of , i=1,2,...,n;

3) calculate If t≤Y _j , let N _T =N _T +1;

4) Repeat 2) and 3) for a total of N _sim times;

5) Calculate R ^(j) = N _T /N _sim ;

Step 6: Calculate task reliability:

Define "task reliability" as the probability that the total delay of information packet transmission for each service in each stage of the task profile is less than or equal to the corresponding specified delay threshold;

When each business in each phase of the task profile meets the delay requirement, the entire task meets the requirement; otherwise, as long as there is at least one business that cannot meet the delay requirement, the task fails; according to the reliability theory, the calculation task reliability The mathematical model should adopt a serial model; thus, if the task profile contains a total of M services, the task reliability R is the product of the transmission reliability of all services, that is

In the formula: R ^(j) is the transmission reliability of service j;

Through the above steps, the purpose of quantitative analysis of the reliability level of the formation wireless communication network under the multi-stage and multi-service mission profile is achieved, which meets the actual needs of engineering and solves the reliability evaluation of the formation wireless communication network in complex situations Considering the actual needs, communication characteristics and transmission mechanism, it ensures that the analysis process is scientific, reasonable and close to the actual situation, and the reliability evaluation results are credible. Strong application value;

Among them, the "information packet" mentioned in step 1 refers to the smallest unit into which information such as message, voice or video is divided; information packet; the "packet error rate" refers to the probability of generating an error packet; the "service" refers to different types of information such as messages, voice or video, etc. that are carried out by the formation wireless communication network to complete tasks. delivery behavior;

Wherein, the "task profile" described in step 2 refers to the sequence description of events experienced by the formation wireless communication network during the period of completing the task; the "communication node" (referred to as "node") is Refers to individuals equipped with wireless communication equipment, such as infantry carrying portable radio equipment, vehicles equipped with wireless communication equipment, ships equipped with wireless communication equipment, etc.;

Wherein, the "delay distribution" described in step 4 refers to the distribution of time consumed by a certain node during the transmission of information packets of a certain service;

Wherein, the "total delay" mentioned in step 5 refers to the sum of the time consumed by the information packet of a certain service on all the nodes it passes through from the sending terminal to the receiving terminal.

(3) Advantages:

The present invention proposes a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage multi-service task profile under the formation wireless communication network reliability evaluation method, and its advantages are as follows:

① The present invention quantitatively analyzes the reliability level of the formation wireless communication network under the multi-stage and multi-service task profile, meets the actual needs of engineering, and solves the reliability evaluation problem of the formation wireless communication network under complex situations;

②The present invention considers the actual needs, communication characteristics and transmission mechanism, which ensures that the analysis process is scientific, reasonable and close to the actual situation, and the reliability evaluation results are credible;

③ The reliability evaluation method proposed by the present invention is simple in calculation, convenient for engineering and technical personnel to use, and has strong application value.

④

Description of drawings

Fig. 1 is a flow chart of the method of the present invention.

Figure 2 is a task profile of a certain ship formation, including 3 stages and 4 operations.

Figure 3 is a schematic diagram of the business of a ship formation, involving five nodes (that is, ships equipped with wireless communication equipment), and the arrows between the nodes indicate the transmission direction of the corresponding business information packets; specifically,

Business 1: Node 1 generates an information packet, passes through Node 2, and finally delivers it to Node 3;

Service 2: Node 1 generates an information packet, passes through node 4, and finally delivers it to node 5;

Business 3: Node 3 generates an information packet, passes through Node 2, and finally delivers it to Node 1;

Service 4: Node 5 generates an information packet, passes through Node 4, and finally delivers it to Node 1.

Detailed ways

The present invention proposes a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage multi-service task profile under the formation wireless communication network reliability evaluation method, the flow chart shown in Figure 1 .

Taking the wireless communication network of a ship formation as an example, the present invention will be further described in detail. The task profile of the ship formation is shown in Figure 2; the business schematic diagram is shown in Figure 3; the information packet generation rate of the four services is the same, λ ^(j) = 5/s, j = 1, 2, 3, 4; The standard length of each service information packet is the same, L=1024 bits; the information packet processing rate of each node is the same, μ=15/second; bit error rate p _{error bit} =0.001; packet loss rate p _loss =0.01; The ratio threshold K=0.005; the delay thresholds of the four services are the same, Y _j =1 second, j=1,2,3,4.

The specific implementation steps are as follows:

Step 1: Calculate the packet error rate of each service:

The packet error rates of the four services are the same, and the calculated

In the formula: Indicates rounding up operation;

Step 2: Analyze the arrival and departure rate of information packets on each node of each service and each stage in the task profile:

According to the analysis of Table 1 and Table 2, the arrival and departure rate of information packets on each node of each service in each stage in the mission profile are obtained, and the equations are established together, and then all unknown parameters are solved.

Phase 1, business 1:

Phase 1, Business 2:

Phase 2, business 3:

Phase 3, Business 4:

In the formula: is the rate at which node 1 completes information processing for service 1; is the rate at which node 2 completes information processing for service 1; is the rate at which node 3 completes information processing for service 1; is the rate at which node 1 completes information processing for service 2; is the rate at which node 4 completes information processing for service 2; is the rate at which node 5 completes information processing for service 2; is the rate at which node 3 completes information processing for service 3; is the rate at which node 2 completes information processing for service 3; is the rate at which node 1 completes information processing for service 3; is the rate at which node 5 completes information processing for service 4; is the rate at which node 4 completes information processing for service 4; is the rate at which node 1 completes information processing for service 4;

Step 3: Calculate the effective arrival rate of packets on each node in each phase of the mission profile:

Phase 1:

Phase 2:

Phase 3:

In the formula: is the effective arrival rate of packets from node 1 in phase 1 of the mission profile; is the effective arrival rate of packets from node 2 in phase 1 of the mission profile; is the effective arrival rate of packets from node 3 in phase 1 of the mission profile; is the effective arrival rate of packets from node 4 in phase 1 of the mission profile; is the effective arrival rate of packets from node 5 in phase 1 of the mission profile; is the effective arrival rate of packets from node 1 in phase 2 of the mission profile; is the effective arrival rate of packets from node 2 in phase 2 of the mission profile; is the effective arrival rate of packets from node 3 in phase 2 of the mission profile; is the effective arrival rate of packets from node 1 in phase 3 of the mission profile; is the effective arrival rate of packets from node 4 in phase 3 of the mission profile; is the effective arrival rate of packets from node 5 in phase 3 of the mission profile;

Step 4: Calculate the parameters of the delay distribution on each node in each stage of the task profile:

Phase 1:

Phase 2:

Phase 3:

In the formula: is the parameter of the delay distribution on node 1 in phase 1 of the mission profile; is the parameter of the delay distribution on node 2 in phase 1 of the mission profile; is the parameter of the delay distribution on node 3 in phase 1 of the mission profile; is the parameter of the delay distribution on node 4 in phase 1 of the mission profile; is the parameter of the delay distribution on node 5 in phase 1 of the mission profile; is the parameter of the delay distribution on node 1 in phase 2 of the mission profile; is the parameter of the delay distribution on node 2 in phase 2 of the mission profile; is the parameter of the delay distribution on node 3 in phase 2 of the mission profile; is the parameter of the delay distribution on node 1 in phase 3 of the mission profile; is the parameter of the delay distribution on node 4 in phase 3 of the mission profile; is the parameter of the delay distribution on node 5 in phase 3 of the mission profile;

Step 5: Calculate the transmission reliability of each service:

Since the parameters of the delay distribution on some nodes are relatively close, the Monte Carlo simulation method is used to calculate the transmission reliability of each service, and the total number of simulations is N _sim = 100000, and the calculation is

In the formula: R ⁽¹⁾ is the transmission reliability of service 1; R ⁽²⁾ is the transmission reliability of service 2; R ⁽³⁾ is the transmission reliability of service 3; R ⁽⁴⁾ is the transmission reliability of service 4 ;

Step 6: Calculate task reliability:

Finally, the mission reliability of the ship formation wireless communication network is obtained as

In the formula: R is the task reliability;

In summary, the present invention proposes a multi-stage multi-service formation wireless communication network reliability evaluation method, that is, a multi-stage, multi-service mission profile reliability evaluation method for formation wireless communication networks, which is oriented to practical engineering In view of the complex situation of multi-stage and multi-service task profiles, the influencing factors such as packet loss, bit error and retransmission mechanism are analyzed. The analysis process is scientific, reasonable and close to the actual situation, and the reliability evaluation results are credible. , the proposed method is simple to calculate, convenient for engineering and technical personnel to use, and has strong application value.

Claims (5)

1. a method for evaluating reliability of a formation wireless communication network under a multi-stage multi-service, namely a method for evaluating reliability of a formation wireless communication network under a multi-stage multi-service task profile, characterized in that: the specific implementation steps are as follows: Step 1: Calculate the packet error rate of each service: Since communication equipment usually has a predetermined error correction capability, only when the proportion of error codes in the information packet exceeds the error correction capability of the communication equipment, the information packet cannot be received correctly; based on the above understanding, "error packet" is defined as an error code The proportion of information packets greater than or equal to the specified threshold, and define "error packet rate" as the probability of generating error packets; Assume that for each service, the standard length of the information packet is the same, which is recorded as L bits; the bit error rate is the same, which is recorded as p _{bit error} ; the threshold value of the bit error ratio is the same, which is recorded as K; then, the packet error rate p _{error packet} is given by the following formula calculation In the formula: N _{error bit} is the number of bit error, Indicates rounding up operation; Step 2: Analyze the arrival and departure rate of information packets on each node of each service and each stage in the task profile: Any communication node in the formation wireless communication network can be used not only as a sending and receiving terminal, but also as a relay node; at the same time, the communication between nodes is affected by packet loss and bit error, and there is a situation of packet retransmission; suppose when a The receiving node, that is, the receiving terminal or relay node does not receive an information packet, that is, when a packet loss occurs, or when an information packet is received, but it is found to be an error packet after processing, it will immediately request the upper node to resend the information packet, and the upper node will Retransmit the packet immediately, and the time consumed from requesting retransmission to executing retransmission is small enough to be ignored; There are four types of sources of packets to be processed on a node, or "arriving packets": 1) As a packet generated by the sending terminal: For business j, if node i is a sending terminal, record the rate at which it generates information packets as λ ^(j) ; 2) Receive the information packet sent by the upper node: For service j, if node i is a relay node or a receiving terminal, record the rate at which the superior node completes information processing as And the packet loss rate of each service is the same, which is recorded as p _{packet loss} ; due to the existence of error packets, only the information packets with a ratio of 1-p _{error packets} are correct and can be sent to node i; due to packet loss, the information packets sent to node i Only information packets with a ratio of 1-p _{packet loss} can be received; therefore, the arrival rate of information packets sent by the superior node is 3) Information packets that are required to be retransmitted by lower-level nodes due to packet loss: For business j, if node i is a relay node or a sending terminal, record the rate at which node i completes information processing as For the lower-level nodes, the packet loss rate is found to be Since the lower-level node will immediately request retransmission when it finds packet loss, and the time consumed from requesting retransmission to executing retransmission is ignored, the rate at which node i is requested to retransmit due to packet loss is equal to the rate at which the lower-level node finds packet loss; 4) Information packets that are required to be retransmitted by lower-level nodes due to error packets: For service j, if node i is a relay node or a sending terminal, write down the rate at which the secondary node completes information processing as If the subordinate node is the receiving terminal of service j, Ω is empty, namely Otherwise, Ω is the next-level node; the lower-level node will find out whether it is an error packet after processing the received information packet, so the rate at which the error packet is found is Since the lower-level node finds an error packet, it will immediately request retransmission, and the time consumed from requesting retransmission to executing the retransmission is ignored, so the rate at which node i is required to retransmit by the lower-level node due to an error packet is equal to the rate at which the lower-level node finds an error packet ; Based on the above analysis, the arrival rate of packets from each source is summarized as follows: For business j, if node i is a sending terminal, the rate at which it generates information packets as a sending terminal is λ ^(j) ; for business j, if node i is a relay node or a receiving terminal, its rate of receiving information packets sent by a superior node rate is For service j, if node i is a relay node or a sending terminal, the rate at which it is required to retransmit by lower-level nodes due to packet loss is For service j, if node i is a relay node or a sending terminal, the rate at which it is required to retransmit by lower-level nodes due to error packets is On the other hand, there are two types of destinations for packets that are processed on a node, that is, "leaving packets": 1) Complete business as a receiving terminal: For business j, if node i is the receiving terminal, record the rate at which it completes information processing as 2) After processing the information packet, continue to send the correct information packet to the lower-level node: For service j, if node i is a relay node or a sending terminal, the rate at which it completes information processing is Based on the above analysis, the departure rate of each destination packet is summarized as follows: For service j, if node i is a receiving terminal, the rate at which it completes the service as a receiving terminal is For service j, if node i is a relay node or a sending terminal, after processing the information packet, the rate at which it continues to send the correct information packet to the subordinate node is According to the queuing network theory, when it is in a steady state, each node’s processing process for each business is in a steady state; that is, for the process of node i executing business j, the sum of the arrival rates of all source information packets is equal to all destinations The sum of the departure rates of the packets; Enumerate the arrival rate of information packets from all sources of node i performing business j, and the departure rate of all destination information packets, and establish an equation; then, establish an equation for each node and each business, and a simultaneous equation system, All unknown parameters can be solved; Step 3: Calculate the effective arrival rate of packets on each node in each phase of the mission profile: According to the queuing network theory, the "effective arrival rate" of information packets on a node is the sum of the arrival rates of information packets from all sources of all services undertaken by it, and its value is the same as that of all destination information packets of all services undertaken by it. The sum of the departure rates is equal; therefore, in the mission profile phase w, the effective arrival rate of packets from node i Calculated by the following formula In the formula: λ ^(j) is the rate at which node i generates information packets if it is the sending terminal of service j; p _{packet loss} is the packet loss rate; p _{error packet} is the packet error rate; If node i is the relay node of service j, the rate at which its superior node completes information processing; is the rate at which node i completes information processing if it is a relay node or sending terminal of service j; If node i is the relay node or sending terminal of service j, the rate at which its subordinate nodes complete information processing; is the rate at which node i completes information processing if it is the receiving terminal of service j; Step 4: Calculate the parameters of the delay distribution on each node in each stage of the task profile: Assuming that the packet processing rate of all nodes is the same, denoted as μ; according to the queuing theory, for node i in the task profile phase w, when And when the buffer area of the communication device is large enough, the time delay T _i on node i obeys the reciprocal of the scale parameter as The exponential distribution of Step 5: Calculate the transmission reliability of each service: For a service, define "transmission reliability" as the probability that the total delay of information packet transmission is less than or equal to the specified delay threshold; Assume that the business j in the mission profile phase w is completed by nodes 1, 2, ..., node i, ..., node n, and the delivery order of information packets is consistent with the numbering order of nodes; For business j, the total delay T ^(j) is expressed as Since T _i obeys the parameter as Exponential distribution of T ^(j) cumulative distribution function Expressed as where: t is time; n is the total number of nodes participating in business j in task profile stage w; is the parameter of the delay distribution on node i in the mission profile stage w, that is, the reciprocal of the scale parameter; is the parameter of the delay distribution on node k in the mission profile stage w, that is, the reciprocal of the scale parameter; For service j in mission profile phase w has delay threshold Y _j , the transmission reliability R ^(j) is calculated by the following formula In the formula: n is the total number of nodes participating in the business j in the task profile stage w; is the parameter of the delay distribution on node i in the mission profile stage w, that is, the reciprocal of the scale parameter; is the parameter of the delay distribution on node k in the mission profile stage w, that is, the reciprocal of the scale parameter; There is a problem in the calculation of the analytical expression of the above transmission reliability: when the parameters of the delay distribution on some nodes are similar, the use of computer calculations will produce large errors, resulting in unreasonable results; therefore, a calculation transmission Monte Carlo simulation method of reliability, which can be used as a general method for calculating transmission reliability; For service j in mission profile phase w, the Monte Carlo simulation method of transmission reliability is as follows: 1) The number of times the total initialization delay is less than or equal to the threshold Y _j , let N _T =0; 2) From the parameter as Draw a random number t _i from the exponential distribution of , i=1,2,...,n; 3) calculate If t≤Y _j , let N _T =N _T +1; 4) Repeat 2) and 3) for a total of N _sim times; 5) Calculate R ^(j) = N _T /N _sim ; Step 6: Calculate task reliability: Define "task reliability" as the probability that the total delay of information packet transmission for each service in each stage of the task profile is less than or equal to the corresponding specified delay threshold; When each business in each stage of the task profile meets the delay requirement, the entire task meets the requirement; otherwise, as long as there is at least one business that cannot meet the delay requirement, the task fails; according to the reliability theory, the mathematical calculation of task reliability The model should adopt the series model; thus, if the task profile contains a total of M services, the task reliability R is the product of the transmission reliability of all services, that is In the formula: R ^(j) is the transmission reliability of service j; Through the above steps, the purpose of quantitative analysis of the reliability level of the formation wireless communication network under the multi-stage and multi-service task profile is achieved, which meets the actual needs of engineering and solves the reliability evaluation of the formation wireless communication network in complex situations Considering the actual needs, communication characteristics and transmission mechanism, it ensures that the analysis process is scientific, reasonable and close to the actual situation, and the reliability evaluation results are credible. At the same time, the proposed method is simple to calculate and easy to use by engineers and technicians, and has great potential. Strong application value. 2. The method for evaluating the reliability of a formation wireless communication network under a multi-stage multi-service according to claim 1, that is, a method for evaluating the reliability of a formation wireless communication network under a multi-stage multi-service mission profile, characterized in that : The "information packet" described in step 1 refers to the smallest unit into which message, voice and video information are divided; the "error packet" refers to an information packet with a bit error ratio greater than or equal to a prescribed threshold; The "packet error rate" mentioned above refers to the probability of generating error packets; the "service" mentioned above refers to the transmission behavior of message, voice and video information carried out by the formation wireless communication network to complete the task. 3. The reliability assessment method of formation wireless communication network under a kind of multi-stage multi-service according to claim 1, namely a kind of reliability assessment method of formation wireless communication network under multi-stage and multi-service task profile, it is characterized in that : The "task profile" mentioned in step 2 refers to the sequence description of the events experienced by the formation wireless communication network during the period of completing the task; the "communication node" refers to the individual equipped with wireless communication equipment . 4. The method for evaluating the reliability of a formation wireless communication network under a multi-stage multi-service according to claim 1, that is, a method for evaluating the reliability of a formation wireless communication network under a multi-stage and multi-service mission profile, characterized in that : The "delay distribution" mentioned in step 4 refers to the distribution of time spent on a node during the transmission of information packets of a service. 5. The reliability evaluation method of formation wireless communication network under a kind of multi-stage multi-service according to claim 1, that is, the reliability evaluation method of formation wireless communication network under a multi-stage multi-service mission profile, characterized in that : The "total delay" mentioned in step 5 refers to the sum of the time consumed by the information packet of a service from the sending terminal to the receiving terminal on all the nodes it passes through.