Calculation method of synchronization performance timeliness index

Abstract

The invention discloses a method for calculating a timeliness index of synchronization performance, and the method comprises the steps: introducing a synchronization age AoS as a performance index in an Internet of Things communication network, and analyzing key influence factors of the synchronization performance of a network system; in the communication part, modeling is carried out on the arrival and transmission process of a data packet by adopting a later arrival first service preemption rule and a Geo-Geo-1 queuing model, and an average peak value AoS and a closed expression of the average AoS in the scene are deduced; the influence of different parameters on the synchronization performance is deeply studied in combination with the performance requirements and distribution characteristics of AoS. According to the method, the synchronization performance of the Internet of Things network can be comprehensively evaluated, and a scientific basis is provided for analyzing and improving the synchronization performance in an Internet of Things communication system.

Description

Technical Field

[0001] The present invention relates to the field of wireless network performance calculation, and in particular to a method for calculating a synchronization performance timeliness index. Background Art

[0002] Wireless networks are widely used in real-time monitoring scenarios such as the Internet of Things (IoT), digital twins (DT), and smart factories. In these applications, it is crucial to ensure real-time synchronization of the states of physical and virtual spaces. Unlike traditional frame synchronization and time synchronization, state synchronization requires ensuring that the environmental state information obtained from the physical world matches the data received by the base station. Therefore, it is necessary to study the synchronization performance of IoT networks, focusing on the freshness of information. In recent years, performance indicators related to information freshness have attracted widespread attention, among which the age of information (AoI) is an important metric used to measure the time since the latest update packet was generated. However, AoI only focuses on the time since the packet was generated, without considering the state changes of the transmitter. In order to more accurately evaluate the network synchronization state, the synchronization age (AoS) indicator is introduced to measure the duration of the state of the receiver and the transmitter since they are out of sync, which is more suitable for analyzing the synchronization performance of digital wireless networks. Summary of the invention

[0003] Purpose of the invention: Aiming at the state synchronization problem in the Internet of Things network, the purpose of the present invention is to provide a method for calculating the timeliness index of synchronization performance, by analyzing the changing law of the synchronization age AoS, evaluating the synchronization and information freshness of the network, and providing a scientific basis and rational guidance for the optimal design of synchronization performance in the IoT system.

[0004] Technical solution, in order to achieve the above-mentioned invention object, the present invention proposes a method for calculating the synchronization performance timeliness index, the method comprising the following steps:

[0005] Step 1) Establishing an IoT communication model, including a network topology model and a data packet transmission model;

[0006] Step 2) Calculate the transmission success probability based on the IoT communication model;

[0007] Step 3) Introduce the synchronization age AoS performance indicator, and use the transmission success probability, i.e., service rate, and packet arrival rate to derive a closed expression for the average peak synchronization age PAoS in the network;

[0008] Step 4) obtaining a closed expression of the average synchronization age AoS;

[0009] Step 5) The synchronization performance timeliness is obtained according to the closed expression of the average peak synchronization age PAoS and the average synchronization age AoS.

[0010] Further, the specific method of step 1) is as follows:

[0011] Step 1.1) In the IoT communication network, a network scenario is constructed including a base station and multiple sensor nodes. The sensor nodes collect environmental data and transmit the data to the base station via an uplink;

[0012] Step 1.2) The packet arrival and transmission modeling adopts the Geo / Geo / 1 queuing model, in which the packet arrival process is geometrically distributed, the service process follows the geometric distribution, and the queuing rule adopts the last-come-first-served preemption rule.

[0013] Further, the specific method of step 2) is as follows:

[0014] Step 2.1) Under a given topology, the conditional transmission success probability from the sensor node to the base station is expressed as:

[0015] μ Φ =P(γ CB >θ|Φ)

[0016] Among them, γ CB represents the signal-to-interference-to-noise ratio at the base station; Φ represents the IoT topology; θ represents the signal-to-interference-to-noise ratio threshold;

[0017] Step 2.2) Select a sensor and calculate the signal-to-interference-to-noise ratio γ from the sensor to the base station CB :

[0018]

[0019] Where r0 represents the distance from the selected sensor to the base station; α represents the path loss coefficient; h0 represents the Rayleigh fading between the selected sensor and the base station; r i represents the distance from the ith sensor to the base station after removing the selected sensor; h i represents the Rayleigh fading between the ith sensor and the base station after removing the selected sensor;

[0020] Step 2.3) Using γ CB Calculate the transmission success probability under this network:

[0021]

[0022] Further, the specific method of step 3) is as follows:

[0023] Step 3.1) introduces the synchronization age AoS, which is defined as the duration since the sender and the receiver are out of sync, and the expression is:

[0024] Δ S (t)=(tU S (t))+

[0025] Among them, U S (t) = min{t j |t j >t M(t)},U S (t) represents the time when the sensor node updates its data packet for the first time after the base station last receives the data packet, t1, t2, ..., t j Indicates the time when the data packet arrives, M(t) is the sequence number of the latest data packet received at time t; Δ S (t) represents the AoS at time t; (.) + =max(.,0), and when the base station is synchronized with the sensor node, Δ S (t) = 0;

[0026] Step 3.2) Calculate the expression for the average peak synchronization age PAoS, which is derived as follows:

[0027]

[0028] Among them, X i represents the arrival interval between the i-1th and i-th data packets, following a geometric distribution. λ represents the packet arrival rate; S i represents the service time of the ith data packet, following a geometric distribution, P i represents the peak value that can be achieved when the i-th data packet is transmitted; M represents the number of peak values; In S i ≤X i The time value is 1, in S i >X i The time value is 0;

[0029] Step 3.3) Using the peak value P i It will only exist if the data packet service succeeds, that is, S i ≤X i The peak value P is calculated based on the rule i :

[0030]

[0031] Among them, B i Represents the AoS value at the time when the i-th data packet arrives;

[0032] From this we can see that E[P i ]:

[0033] E[P i ]=(E[B i ]+E[Si ]-1)P[S i ≤X i ]

[0034] Step 3.4) Given B i Independent of S i and X i , we get E[B i ]=E[B i+1 ],Depend on Recursive relation calculation E[B i ]:

[0035]

[0036] in, In X i <S i The time value is 1, in S i >X i The time value is 0;

[0037] Step 3.5) Using E[B i ] Calculate E[Pi] and substitute it into A p The expression of the average peak synchronization age PAoS is obtained by:

[0038]

[0039] Further, the specific method of step 4) is as follows:

[0040] Step 4.1) Calculate the expression for the average synchronization age AoS:

[0041]

[0042] Among them, E[R i ] represents the mean of the sum of the synchronization ages between the transmission times of the i-th data packet and the i+1-th data packet;

[0043] Step 4.2) Calculate R from geometric relationship i The expression is:

[0044]

[0045] It can be seen from this that E[R i ]:

[0046]

[0047] Step 4.3) Using E[B i ]Calculate E[R i ] and bring it into A aveThe expression of the average synchronization age AoS is obtained as follows:

[0048]

[0049] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0050] The present invention proposes a synchronization performance analysis method based on synchronization age AoS. By analyzing the changing law of synchronization age AoS, the synchronization and information freshness of the network are evaluated, providing a scientific basis and rational guidance for the optimization design of synchronization performance in the IoT system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a specific flow chart of the method for evaluating the timeliness of information transmission synchronization in the Internet of Things in an embodiment of the present invention;

[0052] Figure 2 It is a performance analysis diagram of the change of AoI and AoS as the arrival rate λ increases in the communication scenario of the present invention. DETAILED DESCRIPTION

[0053] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0054] like Figure 1 As shown, the present invention proposes a method for calculating a synchronization performance timeliness index, the method comprising the following steps:

[0055] Step 1) Establishing an IoT communication model, including a network topology model and a data packet transmission model;

[0056] Step 2) Calculate the transmission success probability based on the IoT communication model;

[0057] Step 3) Introduce the synchronization age AoS performance indicator, and use the transmission success probability, i.e., service rate, and packet arrival rate to derive a closed expression for the average peak synchronization age PAoS in the network;

[0058] Step 4) obtaining a closed expression of the average synchronization age AoS;

[0059] Step 5) The synchronization performance timeliness is obtained according to the closed expression of the average peak synchronization age PAoS and the average synchronization age AoS.

[0060] Further, the specific method of step 1) is as follows:

[0061] Step 1.1) In the IoT communication network, a network scenario is constructed including a base station and multiple sensor nodes. The sensor nodes collect environmental data and transmit the data to the base station via an uplink;

[0062] Step 1.2) The packet arrival and transmission modeling adopts the Geo / Geo / 1 queuing model, in which the packet arrival process is geometrically distributed, the service process follows the geometric distribution, and the queuing rule adopts the last-come-first-served preemption rule.

[0063] Further, the specific method of step 2) is as follows:

[0064] Step 2.1) Under a given topology, the conditional transmission success probability from the sensor node to the base station is expressed as:

[0065] μ Φ =P(γ CB >θ|Φ)

[0066] Among them, γ CB represents the signal-to-interference-to-noise ratio at the base station; Φ represents the IoT topology; θ represents the signal-to-interference-to-noise ratio threshold;

[0067] Step 2.2) Select a sensor and calculate the signal-to-interference-to-noise ratio γ from the sensor to the base station CB :

[0068]

[0069] Where r0 represents the distance from the selected sensor to the base station; α represents the path loss coefficient; h0 represents the Rayleigh fading between the selected sensor and the base station; r i represents the distance from the ith sensor to the base station after removing the selected sensor; h i represents the Rayleigh fading between the ith sensor and the base station after removing the selected sensor;

[0070] Step 2.3) Using γ CB Calculate the transmission success probability under this network:

[0071]

[0072] Further, the specific method of step 3) is as follows:

[0073] Step 3.1) introduces the synchronization age AoS, which is defined as the duration since the sender and the receiver are out of sync, and the expression is:

[0074] Δ S (t)=(tU S (t)) +

[0075] Among them, US (t) = min{t j |t j >t M(t)},U S (t) represents the time when the sensor node updates its data packet for the first time after the base station last receives the data packet, t1, t2, ..., t j Indicates the time when the data packet arrives, M(t) is the sequence number of the latest data packet received at time t; Δ S (t) represents the AoS at time t; (.) + =max(.,0), and when the base station is synchronized with the sensor node, Δ S (t) = 0;

[0076] Step 3.2) Calculate the expression for the average peak synchronization age PAoS, which is derived as follows:

[0077]

[0078] Among them, X i represents the arrival interval between the i-1th and i-th data packets, following a geometric distribution. λ represents the packet arrival rate; S i represents the service time of the ith data packet, following a geometric distribution, P i represents the peak value that can be achieved when the i-th data packet is transmitted; M represents the number of peak values; In S i ≤X i The time value is 1, in S i >X i The time value is 0;

[0079] Step 3.3) Using the peak value P i It will only exist if the data packet service succeeds, that is, S i ≤X i The peak value P is calculated based on the rule i :

[0080]

[0081] Among them, B i Represents the AoS value at the time when the i-th data packet arrives;

[0082] From this we can see that E[P i ]:

[0083] E[P i ]=(E[B i ]+E[S i ]-1)P[S i ≤X i]

[0084] Step 3.4) Given B i Independent of S i and X i , we get E[B i ]=E[B i+1 ],Depend on Recursive relation calculation E[B i ]:

[0085]

[0086] in, In X i <S i The time value is 1, in S i >X i The time value is 0;

[0087] Step 3.5) Using E[B i ]Calculate E[P i ], and bring in A p The expression of the average peak synchronization age PAoS is obtained by:

[0088]

[0089] Further, the specific method of step 4) is as follows:

[0090] Step 4.1) Calculate the expression for the average synchronization age AoS:

[0091]

[0092] Among them, E[R i ] represents the mean of the sum of the synchronization ages between the transmission times of the i-th data packet and the i+1-th data packet;

[0093] Step 4.2) Calculate R from geometric relationship i The expression is:

[0094]

[0095] It can be seen from this that E[R i ]:

[0096]

[0097] Step 4.3) Using E[B i ]Calculate E[R i ] and bring it into A ave The expression of the average synchronization age AoS is obtained as follows:

[0098]

[0099] To verify the accuracy of the analysis results, they are compared with the measured data obtained through Monte Carlo simulation. The system parameters are set as follows: path loss index α = 3, signal-to-interference-noise ratio threshold θ = 5, radius of each cluster R = 90m, μ Φ =0.2, the service rate μ Φ The arrival rate λ is used as the index to measure the synchronization performance of the IoT network, and the synchronization performance of the IoT network under different parameters can be obtained.

[0100] like Figure 2 As shown in the figure, the simulation results show the changing trends of multiple synchronization performance indicators under different packet arrival intervals. First, as the packet arrival interval increases, the probability of successful transmission of a packet in a single sending cycle increases, resulting in a gradual increase in the average synchronization age. The results show that the average peak synchronization age only occurs when the packet is successfully received and is directly affected by the service time. In addition, the synchronization age indicator is the lower bound of the information age. As the packet arrival rate gradually increases, the information age is higher than the synchronization age. The simulation also shows the relationship between the synchronization age and the information age in the same system. As the arrival rate increases, the related indicators of the information age decrease, while the related indicators of the synchronization age increase, and the two eventually show a convergence trend, verifying the theoretical analysis that the two eventually converge.

Claims

1. A method for calculating a synchronization performance timeliness index, characterized in that: The method comprises the following steps: Step 1) Establishing an IoT communication model, including a network topology model and a data packet transmission model; Step 2) Calculate the transmission success probability based on the IoT communication model; Step 3) Introduce the synchronization age AoS performance indicator, and use the transmission success probability, i.e., service rate, and packet arrival rate to derive a closed expression for the average peak synchronization age PAoS in the network; Step 4) obtaining a closed expression of the average synchronization age AoS; Step 5) The synchronization performance timeliness is obtained according to the closed expression of the average peak synchronization age PAoS and the average synchronization age AoS.

2. The method for calculating the synchronization performance timeliness index according to claim 1, characterized in that: The specific method of step 1) is as follows: Step 1.1) In the IoT communication network, a network scenario is constructed including a base station and multiple sensor nodes. The sensor nodes collect environmental data and transmit the data to the base station via an uplink; Step 1.2) The packet arrival and transmission modeling adopts the Geo / Geo / 1 queuing model, in which the packet arrival process is geometrically distributed, the service process follows the geometric distribution, and the queuing rule adopts the last-come-first-served preemption rule.

3. The method for calculating the synchronization performance timeliness index according to claim 2, characterized in that: The specific method of step 2) is as follows: Step 2.1) Under a given topology, the conditional transmission success probability from the sensor node to the base station is expressed as: m Φ =P(γC B >θ|Φ) Among them, YC B represents the signal-to-interference-to-noise ratio at the base station; Φ represents the IoT topology; θ represents the signal-to-interference-to-noise ratio threshold; Step 2.2) Select a sensor and calculate the signal-to-interference-to-noise ratio γc from the sensor to the base station B : Where r0 represents the distance from the selected sensor to the base station; α represents the path loss coefficient; h0 represents the Rayleigh fading between the selected sensor and the base station; r i represents the distance from the ith sensor to the base station after removing the selected sensor; h i represents the Rayleigh fading between the ith sensor and the base station after removing the selected sensor; Step 2.3) Using γ CB Calculate the transmission success probability under this network:

4. The method for calculating the synchronization performance timeliness index according to claim 3 is characterized in that: The specific method of step 3) is as follows: Step 3.1) introduces the synchronization age AoS, which is defined as the duration since the sender and the receiver are out of sync, and the expression is: Δ S (t)=(t-U S (t)) + Among them, U S (t) = min{t j |t j >t M(t) },U S (t) represents the time when the sensor node updates its data packet for the first time after the base station receives the data packet for the last time, t1, t2, ..., t j Indicates the time when the data packet arrives, M(t) is the sequence number of the latest data packet received at time t; Δ S (t) represents the AoS at time t; (.) + =max(.,0), and when the base station is synchronized with the sensor node, Δ S (t) = 0; Step 3.2) Calculate the expression for the average peak synchronization age PAoS, which is derived as follows: Among them, X i represents the arrival interval between the i-1th and i-th data packets, following a geometric distribution. λ represents the packet arrival rate; S i represents the service time of the ith data packet, following a geometric distribution, P i represents the peak value that can be achieved when the i-th data packet is transmitted; M represents the number of peak values; In S i ≤X i The time value is 1, in S i >X i The time value is 0; Step 3.3) Using the peak value P i It will only exist if the data packet service succeeds, that is, S i ≤X i The peak value P is calculated based on the rule i : Among them, B i Represents the AoS value at the time when the i-th data packet arrives; From this we can see that E[P i ]: E[P i ]=(E[B i ]+E[S i ]-1)P[S i ≤X i ] Step 3.4) Given that B i Independent of S i and X i , we get E[B i ]=E[B i+1 ],Depend on Recursive relation calculation E[B i ]: in, In X i i The time value is 1, in S i >X i The time value is 0;​ Step 3.5) Using E[B i ]Calculate E[P i ], and bring in A p The expression of the average peak synchronization age PAoS is obtained by:

5. The method for calculating the synchronization performance timeliness index according to claim 4, characterized in that: The specific method of step 4) is as follows: Step 4.1) Calculate the expression for the average synchronization age AoS: Among them, E[R i ] represents the mean of the sum of the synchronization ages between the transmission times of the i-th data packet and the i+1-th data packet; Step 4.2) Calculate R from geometric relationship i The expression is: It can be seen from this that E[R i ]: Step 4.3) Using E[B i ]Calculate E[R i ] and bring it into A ave The expression of the average synchronization age AoS is obtained as follows:

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