CN108430082A - A vehicle network switching method in a heterogeneous vehicle networking environment - Google Patents

Abstract

The invention discloses the In-vehicle networking switching methods under a kind of isomery car networking environment, belong to car networking field of communication technology.The method constructs in vehicle mobile terminals vehicle-mounted user for the assessment utility function of cordless communication network first；Then the network switching decision model under the heuristic isomery car networking environment of biology is established；Finally use the optimal network accessed after multiple attributive decision making method selection switching.The present invention has considered the QoS demand condition of vehicular applications in the handling capacity factor and different vehicle mobile terminals of heterogeneous network environment, the rapid vehicle-carrying communication environment for adapting to dynamic change, comparatively fast reach global optimum, effectively prevent " ping-pong " in tradition switching theory, so that network switching is more intelligent, adaptivity and robustness with height；The present invention takes full advantage of the advantage of biocenose intelligence computation, maintains the fairness of global network resource allocation and has ensured the global benefit of limited Internet usage.

Description

A vehicle network switching method in a heterogeneous vehicle networking environment

technical field

The invention belongs to the technical field of vehicle networking communication, and relates to a biological intelligent network switching method, in particular to a vehicle network switching method in a heterogeneous vehicle networking environment.

Background technique

The integrated application of traditional cellular wireless network, wireless local area network and vehicle information technology has promoted the birth of heterogeneous vehicle networking. The integration, interoperability and fusion of wireless communication networks with different characteristics have become the main trend of the current evolution of vehicle networking, supporting intelligent vehicle Terminal interaction, computing, and decision-making are important features of the development of heterogeneous Internet of Vehicles applications. The in-vehicle information service based on the heterogeneous Internet of Vehicles has gradually become the core functional element of the intelligent traffic system (Intelligent Traffic System, ITS).

Handover management (Handover Management) is an important topic in the field of heterogeneous wireless network research. In the process of mobile communication, when a terminal enters a new network service area from the current network service area, the link connected to the original wireless network base station or access point switch to a new wireless network base station or a new access point, and continue to maintain the network communication link on the terminal. The seamlessness of network handover and the automation of the handover process require that the handover technology can satisfy mobile terminals with multi-mode communication functions to autonomously handover from a variety of optional networks to the most suitable access network. For in-vehicle information systems, in-vehicle mobile terminals realize autonomous decision-making, rationally select wireless networks to access, and dynamically switch between different network ports.

Due to the dynamic characteristics of the heterogeneous Internet of Vehicles environment, wireless network conditions change in real time over time, which will involve dynamic changes in parameters, while traditional network handover decision optimization methods based on utility functions and multi-attribute decision-making are mainly based on the optimal value of parameters. Switching can easily cause a "ping-pong" effect. Frequent network switching not only accelerates the energy consumption of vehicle-mounted mobile terminal hardware devices, but will eventually affect the efficiency of the entire network communication service.

Network handover in a heterogeneous Internet of Vehicles environment faces challenges such as the diversity of Quality of Service (QoS) requirements for in-vehicle applications, the heterogeneity and dynamics of wireless networks, and the concurrency of multi-terminal resource competition. Therefore, how can a vehicle-mounted mobile terminal independently, optimally, and reliably select a reasonable target network for various vehicle-mounted applications under the condition of satisfying certain network resource constraints and vehicle-mounted application QoS requirements constraints, and how to choose a reasonable target network based on dynamically changing network conditions and vehicle-mounted mobile environments? Handover between heterogeneous wireless links has become the core issue of multi-mode communication applications in the heterogeneous Internet of Vehicles environment.

Contents of the invention

Taking the heterogeneous vehicle networking environment as the background, the present invention proposes a biologically inspired vehicle network switching method in the heterogeneous vehicle networking environment. The vehicle-mounted network handover method applies a biologically-inspired intelligent method—the cell attractor selection model, to the optimization decision-making problem of vehicle-mounted mobile terminal network handover in a dynamic heterogeneous network environment, and makes full use of it while meeting the QoS requirements of vehicle-mounted applications. It not only maintains the fairness of global network resource allocation, but also guarantees the global benefits of limited network resource usage.

The invention simulates the gene expression behavior produced by microbial cells adapting to the dynamic nutritional environment, induces the vehicle-mounted mobile terminal to make adaptive network switching decisions, and compares the dynamic vehicle-mounted mobile terminal to microbial cells. The adaptation mechanism responds quickly, affecting the gene expression inside the microbial cell and the activity of the microbial cell, which in turn affects the generation of cell attractors, and finally induces the vehicle-mounted mobile terminal to make a highly adaptive and robust network switching decision. Moreover, the present invention further combines the multi-attribute decision-making method to evaluate the performance index of the alternative access network, and select the optimal network access suitable for the vehicle-mounted user on the vehicle-mounted mobile terminal.

A vehicle-mounted network switching method in a heterogeneous vehicle-networking environment provided by the present invention, the specific steps are as follows:

Step 1, constructing the evaluation utility function of the vehicle-mounted mobile terminal for the wireless communication network by the vehicle-mounted user;

A. For wireless network i, the number of channels of wireless network i is denoted as C _i (t), and the average throughput of each channel is R _i , assuming that there are n _i (t) vehicle-mounted applications connected to the wireless network at time t network i, then the average throughput q _i (t) that can be received by the vehicle-mounted applications connected to the wireless network at this time is the average value of the total throughput of the wireless network allocated to each vehicle-mounted application. For the vehicle-mounted mobile terminal j, note that each vehicle-mounted mobile terminal has multiple vehicle-mounted users, and each vehicle-mounted user can execute a single vehicle-mounted application after connecting to the wireless network.

B. In order to quantitatively evaluate the quality of service QoS provided by any heterogeneous wireless network i for s-type vehicle applications, the present invention proposes a satisfaction(i, s) function.

C. By weighting the personal preferences of vehicle users for each type of vehicle application, a utility function is proposed to comprehensively measure the utility QoS _j (t) obtained for the communication conditions of the vehicle mobile terminal j currently accessing the wireless network.

Step 2. Establish a network handover decision model in a biologically inspired heterogeneous IoV environment;

A. In order to reflect the overall quality of service h ₁ obtained by vehicle users currently accessing the heterogeneous Internet of Vehicles, the present invention uses the moving average method to sum the QoS _j (t) of each vehicle user within the time period W _j and then move On average, h ₁ is obtained.

At the same time, in order to measure the real-time changing heterogeneous IoV communication environment around the vehicle-mounted mobile terminal j, the present invention proposes an AvgQoS _j (t) utility function. For vehicle-mounted mobile terminal j, it is known that the set of candidate wireless networks that can be connected at time t is Net _j (t), and k _j is a single candidate wireless network, that is, k _j ∈ Net _j (t), thus reflecting the The utility that terminal j can provide from the alternative heterogeneous wireless network.

B. The cell attractor selection model is applied to the dynamic optimization decision-making problem of the vehicle-mounted mobile terminal. The vehicle-mounted mobile terminal performs network switching autonomously according to the QoS requirements of the vehicle-mounted application and the resource constraints of the global wireless network.

Step 3, using a multi-attribute decision-making method to select the optimal network to access after handover;

A. Establish a QoS utility matrix. Since QoS is an important indicator for judging network performance, the present invention takes the service quality QoS obtained by the vehicle-mounted mobile terminal j's vehicle-mounted application from the alternative wireless network as an element of the QoS utility matrix.

B. Calculate the normalized QoS utility matrix. Since the values of the elements of the QoS utility matrix are uneven, weight factors are added to normalize the QoS utility matrix to construct a weight normalization matrix.

C. Determine the positive ideal solution and the negative ideal solution. For the vehicle-mounted application on the vehicle-mounted mobile terminal j, the present invention evaluates the maximum value and the minimum value of the benefit index to obtain a positive ideal solution and a negative ideal solution.

D. Calculate the distance between each candidate wireless network and the positive ideal solution and the negative ideal solution.

E. Calculate how close each candidate wireless network is to the positive ideal solution.

F. Rank the degree of proximity of each candidate wireless network to the positive ideal solution. The candidate wireless network closest to the positive ideal solution among the candidate heterogeneous wireless networks is selected as the access network.

Compared with the prior art, the present invention has the advantages of:

(1) The present invention comprehensively considers the throughput factors of the heterogeneous network environment and the QoS requirement conditions of vehicle-mounted applications on different vehicle-mounted mobile terminals under the environment of the Internet of Vehicles, quickly adapts to the dynamically changing vehicle-mounted communication environment, and quickly reaches the global optimum , which effectively prevents the "ping-pong effect" in the traditional handover theory, making the network handover more intelligent, highly adaptive and robust.

(2) The present invention uses a cell attractor selection model to analyze the regulatory behavior of microbial cell gene networks. Based on its adaptive properties and mathematical representations, the cell attractor is used as a switching decision solution, which is novel. The invention makes full use of the advantages of intelligent computing of biological groups, maintains the fairness of global network resource allocation and guarantees the global benefit of limited network resource usage.

Description of drawings

Figure 1 is a network switching scene diagram in a heterogeneous Internet of Vehicles environment.

FIG. 2 is a schematic flowchart of a vehicle network switching method in a heterogeneous vehicle networking environment provided by the present invention.

Figure 3 is a schematic flow chart of the bioinspired method.

Detailed ways

The method of the present invention will be further described in detail with reference to the accompanying drawings and embodiments.

The present invention provides a vehicle-mounted network switching method in a heterogeneous vehicle networking environment, as shown in the process shown in Figure 2, which specifically includes the following steps:

Step 1, constructing the evaluation utility function of the vehicle-mounted mobile terminal for the wireless communication network by the vehicle-mounted user;

A. For wireless network i, the number of channels of the wireless network is recorded as C _i (t), and the average throughput of each channel is R _i , assuming that there are n _i (t) vehicle-mounted applications connected to the wireless network at time t, Then the average throughput q _i (t) that can be received by the vehicle-mounted application connected to the wireless network at this time is the average value of the total throughput of the wireless network allocated to each vehicle-mounted application, namely:

B, the present invention proposes the satisfaction (i, s) function in order to quantitatively evaluate any wireless network i as the quality of service QoS provided by the vehicular application of s type:

For the vehicle-mounted mobile terminal j, the currently connected wireless network i _j , record the vehicle-mounted application running on the vehicle-mounted mobile terminal as p _{j, s} , then the set of s-type vehicle-mounted applications on the vehicle-mounted mobile terminal is AS _{j, s} . Meanwhile, for s-type vehicle-mounted applications, the maximum throughput requirement limit of this type of vehicle-mounted application is q _s,max , and the minimum throughput requirement limit is q _s,min .

C. Through the weighting of the personal preference of the vehicle-mounted user for each type of vehicle-mounted application, the present invention proposes the following utility function to comprehensively measure the utility obtained for the communication conditions of the current access network of the vehicle-mounted mobile terminal j:

Among them, ω _j,s is the personal preference weight of the vehicle user on the vehicle mobile terminal j for the s type of vehicle application, that is, ω _j,s >0, and ∑ _s∈S ω _j,s =1. s indicates that the type of the in-vehicle application is type s, and S indicates the set of all types of in-vehicle applications.

Step 2. Establish a network handover decision model in a biologically inspired heterogeneous IoV environment;

A. In order to reflect the overall quality of service h ₁ obtained by vehicle users currently accessing the heterogeneous Internet of Vehicles, the present invention uses the moving average method to sum the QoS _j (t) of each vehicle user within the time period W _j and then move On average, the calculation formula of QoS _j (t) is:

At the same time, in order to measure the real-time changing heterogeneous IoV communication environment around the vehicle-mounted mobile terminal j, the present invention proposes an AvgQoS _j (t) utility function. For a vehicle-mounted mobile terminal j, it is known that the set of candidate wireless networks that the vehicle-mounted mobile terminal can connect to at time t is Net _j (t), and k _j ∈ Net _j (t), thus reflecting that the vehicle-mounted mobile terminal j is from the candidate wireless networks The utility that the network can provide:

Wherein, γ ∈ (0, 1]. Because the process of network switching needs to consume the newly accessed network resource, what γ represents is the discount coefficient when the vehicle-mounted mobile terminal switches. For simplicity, the present invention is set to:

h ₂ =AvgQoS _j (t) (6)

B. The present invention focuses on applying the cell attractor selection model to the dynamic optimization decision-making problem of the vehicle-mounted mobile terminal, and the vehicle-mounted mobile terminal performs network switching autonomously according to the QoS requirements of the vehicle-mounted application and the resource constraints of the global wireless network. Simulate the gene expression behavior produced by the adaptability of microbial cells to the dynamic nutritional environment, and induce the vehicle-mounted mobile terminal in the heterogeneous Internet of Vehicles environment to make adaptive network switching decisions.

As shown in Figure 3, the researchers analyzed the mechanism of E. coli cells adapting to changes in external environmental conditions, modeled with the help of coupled differential equations, introduced random noise terms, and obtained the mathematical representation of the cell attractor selection model:

Among them, A represents the degree of cell activity, and η ₁ and η ₂ are independent Gaussian white noises. S(A) and D(A) represent the synthesis and decomposition rates due to cell volume growth:

P and C represent the synthesis rate and loss rate coefficients of cell activity, N ₁ and N ₂ represent the level of nutrients provided by the external living environment, N_thr ₁ and N_thr ₂ represent the thresholds of two nutrients for A increment, n ₁ and n ₂ represents the sensitivity coefficient of cells to these two nutrients.

In the cell attractor selection model, there are two attractors, that is, there are two stable states in the process of cell gene regulation: m ₁ >>m ₂ or m ₂ >>m ₁ . At the same time, the interaction between the cell and the environment is represented by a pair of variables (N ₁ , N ₂ ), in order to adapt to the change of the environment, the choice of the cell will switch from one attractor to another, or, when the environment changes It also maintains the current attractor when no changes are required.

In combination with formulas (4) and (6), the present invention uses the Sigmoid function to map h ₁ and h ₂ to the interval of [0, 10] through the value changes of parameters a and b, and to represent the variables of environmental changes N _i (i=1, 2) are related:

To sum up, the handover decision mechanism proposed by the present invention is induced by the cell attractor: when the selection state of the cell attractor is m ₁ >>m ₂ , the vehicle-mounted mobile terminal proposes network handover, combined with the multi-attribute decision-making method to connect to obtain more utility High network; when cell attractor selection state is m ₂ >>m ₁ or , the vehicle-mounted mobile terminal should maintain the current network access status, and no network switching will occur.

Step 3, using a multi-attribute decision-making method to select the optimal network to be accessed after switching from the candidate wireless networks;

A. Establish a QoS utility matrix. Since QoS is an important index for evaluating network performance, the present invention uses the quality of service QoS obtained by each vehicle-mounted application of the vehicle-mounted mobile terminal j from an alternative wireless network as an element of the QoS utility matrix:

X=[x(k _j , p _{j , s} )] (11)

Among them, let x(k _j , p _{j, s} )=satisfaction(k _j , s).

B. Calculate the normalized QoS utility matrix. Since the values of the elements of the QoS utility matrix are uneven, the QoS utility matrix X is normalized so that the values of the matrix elements are in the interval [0, 1]:

Add the weight factor ω _{j, s} to construct the weight normalization matrix. According to the difference in the personal preference degree of each vehicle user on the vehicle mobile terminal j, weighting is performed to obtain a weight normalization matrix:

y(k _j ,p _j,s )=ω _j,s ×x'(k _j ,p _j,s ) (13)

C. Determine the positive ideal solution and the negative ideal solution. For the vehicle-mounted application on the vehicle-mounted mobile terminal j, the positive ideal solution is obtained and negative ideal solution as follows:

D. Calculate the distance between each candidate wireless network and the positive ideal solution and the negative ideal solution. For each candidate wireless network and the positive ideal solution and negative ideal solution The distance between can be calculated by the following equations:

E. Calculate the score of the closeness of each candidate wireless network to the positive ideal solution. According to the distance between each candidate wireless network and the positive ideal solution and the negative ideal solution, the score of the proximity of each candidate wireless network to the positive ideal solution can be obtained:

F. Sorting the scores of the proximity of each candidate wireless network to the positive ideal solution. Select the candidate wireless network with the highest proximity score among the candidate wireless networks as the access network:

Claims (3)

1. the In-vehicle networking switching method under a kind of isomery car networking environment, it is characterised in that：It is as follows,

Step 1: assessment utility function of the vehicle-mounted user for cordless communication network in construction vehicle mobile terminals；

A, for wireless network i, the channel quantity of wireless network i is denoted as C_i(t) a, the handling capacity of average each channel is R_i, Assuming that there are n by moment t_i(t) a vehicular applications are connected to wireless network i, then are connected to the vehicle-mounted of the wireless network at this time and answer With the average throughput q received_i(t) it is that the wireless network total throughout is distributed to the mean value of each vehicular applications；For vehicle Mobile terminal j is carried, remembers each vehicle mobile terminals there are multiple vehicle-mounted users, each vehicle-mounted user executes after being connected into wireless network Single vehicular applications；

B, using satisfaction (i, s) function, the arbitrary heterogeneous wireless network i of quantitative evaluation provides for s type vehicular applications Service quality QoS,

For vehicle mobile terminals j, the wireless network i that currently connects_j, remember the vehicular applications run in the vehicle mobile terminals For p_{J, s}, then the collection of the vehicular applications composition of s types is combined into AS in the vehicle mobile terminals_{J, s}, meanwhile, for the vehicle-mounted of s types Using the maximum throughput demand boundary of the type vehicular applications is q_{S, max}, minimum handle up demand boundary be q_{S, min}；

C, by vehicle-mounted user for each vehicular applications type personal preference weight, propose utility function synthesis weigh for Vehicle mobile terminals j is currently accessed the effectiveness QoS that the communication condition of wireless network is obtained_j(t)：

Wherein, ω_{J, s}It is vehicle-mounted user on vehicle mobile terminals j for the personal preference weight of s type vehicular applications, i.e. ω_{J, s} ＞ 0, and ∑_s∈Sω_{J, s}=1；S indicates that the type of vehicular applications, S indicate the set of the type of all vehicular applications；

Step 2: establishing the network switching decision model under the heuristic isomery car networking environment of biology；

A, using the method for moving average by period W_jThe QoS of interior each vehicle-mounted user_j(t) rolling average is carried out after summing, is obtained h₁, then QoS_j(t) calculating formula is：

For vehicle mobile terminals j, it is known that the vehicle mobile terminals are combined into Net in the attachable alternative wireless networks collection of moment t_j And k (t),_j∈Net_j(t), to reflect that the utility function that vehicle mobile terminals j can be provided from alternative wireless networks is as follows：

Wherein, γ ∈ (0,1], γ indicates discount factor of vehicle mobile terminals when switching over, to put it more simply, setting：

h₂=AvgQoS_j(t)

B, by the sub- preference pattern of cytotaxis be applied to vehicle mobile terminals dynamic optimization decision problem, vehicle mobile terminals according to The resource constraint of the QoS demand of vehicular applications and global wireless network independently executes network switching；

Step 3: with the optimal network accessed after multiple attributive decision making method selection switching.

2. the In-vehicle networking switching method under a kind of isomery car networking environment according to claim 1, it is characterised in that：Institute The mathematical character form for the sub- preference pattern of cytotaxis stated：

Wherein, A indicates cell mobilization degree, η₁And η₂It is independent from each other white Gaussian noise, S (A) and D (A) represent cell volume Synthesis and decomposition rate caused by increasing：

P and C represents the synthetic ratio and loss rate coefficient of cell mobilization degree, N₁And N₂The nutrients of external survival environment offer is provided Matter is horizontal, N_thr₁And N_thr₂Two kinds of nutriments are represented for the threshold value of A increments, n₁And n₂Indicate cell for both The sensitivity coefficient of nutriment；

With Sigmoid functions, changed by the value of parameter a and b, by h₁And h₂It is mapped in the section of [0,10], with representative The variable N of environmental change situation_iIt is associated：

When cytotaxis selects state for m₁＞ ＞ m₂When, vehicle mobile terminals suggestion carries out network switching, determines in conjunction with more attributes Plan method, which is connected to, to be obtained on the higher network of effectiveness；When cytotaxis selects state for m₂＞ ＞ m₁OrWhen, Vehicle mobile terminals should keep present access network state, and network switching does not occur.

3. the In-vehicle networking switching method under a kind of isomery car networking environment according to claim 1, it is characterised in that：Step Rapid three specifically,

A, QoS utility matrix is established；

B, the QoS utility matrix of standardization is calculated；

QoS utility matrix X is subjected to standardization processing so that matrix element value is located in [0,1] section：

Weight factor ω is added_{J, s}, construct weight Standard Process；For vehicle-mounted individual subscriber each of on vehicle mobile terminals j The difference of preference is weighted to obtain weight Standard Process：

y(K_j, p_{J, s})=ω_{J, s}×x′(k_j, p_{J, s})

C, positive ideal solution and minus ideal result are determined：

D, each alternative wireless networks are calculated respectively at a distance from positive ideal solution and minus ideal result；

For each alternative wireless networks respectively with positive ideal solutionAnd minus ideal resultThe distance between pass through following equations group meter It calculates：

E, the degree of closeness score of each alternative wireless networks and positive ideal solution is calculated：

F, each alternative wireless networks and the degree of closeness score size of positive ideal solution are ranked up, it will be in alternative wireless networks The alternative wireless networks of degree of closeness highest scoring are selected as access network：