KR20060063624A - An Access Network Selection Method Using Fuzzy Multi-criteria Decision Making in Heterogeneous Networks - Google Patents

Abstract

According to the present invention, subscribers selectively access an access network that is advantageous for communication quality and billing according to a propagation environment and service characteristics, and effectively use radio resources and traffic of a heterogeneous access network in a global heterogeneous network environment. The present invention relates to an access network selection system and a method using a fuzzy multi-criteria decision making method that can provide a method for increasing subscriber capacity through distribution. In the heterogeneous network of the present invention, an access network selection method using a fuzzy multi-criteria decision method is a method of selecting an optimal access network using a membership function and a decision function using an access network selection parameter for multi-criteria decision making. There is a technical feature in that.

Accordingly, in the heterogeneous network of the present invention, the access network selection method using the fuzzy multi-criteria decision-making method provides subscribers with freedom of mobility as well as access network selection in a heterogeneous network environment composed of heterogeneous access networks, It has the effect of effectively managing infrastructure resources.

Heterogeneous network, access network selection parameters, access network selection policy, decision function, weight vector, fuzzy theory

Description

Access network selection method using multi-criteria decision making in mobile heterogeneous network

1 is an embodiment of an access network selection parameter classified according to a classification policy according to the present invention.

2 is an embodiment of a primary selection process for an access network according to an embodiment of the present invention.

3 is a membership function of language variable values for a decision matrix according to an embodiment of the present invention.

4 is a membership function of language variable values for a weight vector according to an embodiment of the present invention.

The present invention relates to a method of selecting an access network using a fuzzy multi-criteria decision method in a heterogeneous network. More particularly, the present invention relates to a method of selecting an access network using a multi-criteria decision method. Resource management technology for

The 4G mobile communication system, called the next generation mobile communication system, does not exist independently but instead of 3G or WPAN (Wireless Personal Local Area Network) based on the existing 802-series wireless LAN or Bluetooth. It means smooth linkage with 4G mobile communication system. Rather than installing a single wireless access network to cover all areas, it supports high-speed data communication mainly in the hot-spot area, and interlocks with existing systems in areas outside the hot-spot area. This is to provide an optimal service to one mobile terminal.

Therefore, it is necessary to support handover between hierarchical heterogeneous systems so that a terminal can move seamlessly between multiple wireless communication systems while supporting a seamless service. Such handover between hierarchical heterogeneous systems is necessary. Need support for (Hand-over). In addition, in order to achieve such a hierarchical heterogeneous system handover, a QoS management structure that can guarantee a user's QoS based on end-to-end negotiated QoS information must be provided.

In case of selecting an access network using a terminal in a hierarchical heterogeneous system, the destination access network should be selected, but since all access networks have their own system characteristics and roles, they are optimal for performing a specific service at a specific place at a specific time. There is a problem that the selection of an access network is difficult.

Accordingly, the present invention is to solve the problems of the prior art as described above, in the global converged network environment using the multi-criteria decision-making method using the fuzzy operator in consideration of the multiple access network selection factors of the user and operator is best By selecting an access network, a subscriber can access an access network that is advantageous for communication quality and billing, and an operator provides a method for increasing subscriber capacity through effective use of radio resources and traffic distribution of heterogeneous access networks. There is this.

Fuzzy multi-criteria decision making method in a heterogeneous network according to a feature of the present invention for achieving the above object of the present invention,

An access network selection method for providing a service between an application service provider and an end user on a heterogeneous network composed of heterogeneous systems running with different protocols, the method comprising: (a) information of the end user and terminal information of the end user; Selecting an access network based on an access network selection parameter that satisfies a basic condition parameter determined by the application service provider based on the configured context information; and (b) an access network of a user side and a system side among the selected access networks. An optimal access network by performing a main selection step using a multi-critical fuzzy decision method including a predetermined access network selection policy to determine a selection parameter and a priority of the access network selection parameter It comprises selecting a size.

At this time, the method of selecting the optimal access network in the step (b),

(1) determining a decision function and weight vector for applying to the access network selection parameter; (2) selecting a level of the access network selection parameter in consideration of the access network selection policy; (3) determining a membership function value and a fuzzy membership degree for the access network selection parameter and the level of the access network selection policy; (4) determining a weighted membership function value for the access network selection policy; (5) determining a generalized mean value (GMV) from the degree of belonging of the determined weighted membership function to determine priority of access network selection, and (6) selecting an access network based on the determined access network selection priority. It includes a step.

Details of the above object and technical configuration of the present invention and the effects thereof according to the present invention will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

1 is an access network selection parameter classified according to a classification policy according to the present invention.

Referring to FIG. 1, an access network selection parameter required for selecting an access network is set in advance between a mobile terminal and an access network, and includes static information, which is information without periodicity, which does not change once determined. It is divided into dynamic information that periodically changes according to the state of the mobile terminal and the access network. An example of the static information is SLA information, and an example of the dynamic information is the location of the mobile terminal, access network state information, or the like.

The static information may be classified into a device side, which is the mobile terminal itself, and a user side, which receives a multimedia service using the mobile terminal.

On the device side, the authentication information of the access network to which the mobile terminal can connect, the types of applications that can run on the mobile terminal, the QoS requirements of each application, the communication cost level of each application, and the mobility capability of the mobile terminal capability). In addition, the user side includes the user's access network preference, the user's preferred QoS level for the serviced application, and the user's preferred QoS level for the application.

The dynamic information may include current location information of the mobile terminal, QoS parameter information of an application service currently serving by the mobile terminal, and a quantity of resources that may be used by a serving access network and an accessible access network that the mobile terminal is using. Information, the access network being used and available resource information of the accessible access network.

The process of selecting an access network is performed based on the information of FIG. 1. 2 is a first selection process for an access network according to an embodiment of the present invention.

Referring to FIG. 2, a basic condition element is selected based on the information of FIG. 1. The basic condition is a requirement basically required for a mobile terminal to access a specific access network, and the access network is selected first based on this requirement. The basic condition element is composed of received signal strength, authentication, service support, mobile speed limit and available resources.

First, it is determined whether the received signal strength received by the mobile terminal is higher than or equal to a preset level (S200). If the received signal strength is higher than or equal to the preset level, the mobile terminal may access the access network by determining whether the access network is authenticated (S210). Determine whether you are certified. If the mobile terminal can use the access network, it is determined whether the application service that the access network can support (S220).

If the mobile terminal can support the application that the mobile terminal wants to receive from the access network, it determines the movement speed limit of the mobile terminal (S230). If it is possible to provide an application service even at the limit of the moving speed of the mobile terminal, it is determined whether there is an available resource in the access network (S240). If it is determined that there are available resources, it is determined that the access network satisfies all basic conditions desired by the mobile terminal (S250).

At this time, the mobile terminal can access any of the access networks selected through the above processes. If one condition is not satisfied through the determination process, the access network at that time is determined to satisfy the basic condition and is not used.

A second selection process is performed to select an optimal access network among a plurality of access networks that satisfy the first selection process for the access network. The secondary selection process is a main selection step, in which the access network selection parameter, which is necessary for performing this step, is related to the communication cost, user device preference, and end-to-end QoS of the user side of the access network parameters. Based on user preference QoS and system-side access network load selection conditions are required. The optimal access network is selected when communication costs are minimized, user device preference is maximized, user preference QoS based on E2E QoS is maximized, and access network load is minimized.

The access network selection parameter is divided into a user side and a system side as described above to determine which side to give priority based on a predefined access network selection policy. The weight assigned in the access network selection parameter may be adjusted according to a predefined access network selection policy, and accordingly, the access network selection list for the plurality of selectable access networks is dynamically updated.

3 is a membership function of language variable values for a decision matrix according to an embodiment of the present invention, and relates to a method of selecting an optimal access network by acting on an access network selection parameter during the second selection process. will be.

In the secondary selection process, a decision function for the access network selection parameter required to perform the selection step is determined. The decision function A _i (i = 1,2, ... n) for each access network selection parameter is defined as an alternative evaluated by the access network selection parameter C _j (j = 1,2, ... m). In order to express the degree to which the respective alternatives satisfy the access network selection factor, the decision function X is expressed as Equation 1 below.

In Equation 1, x _ij represents the linguistic decision result of alternatives A _i (i = 1, 2,… n) with an access network selection parameter C _j (j = 1, 2,… m). It is expressed as a set of language variables of VP (Very Poor), P (Poor), F (Fair), G (Good), and VG (Very Good). The membership function of the language variable values used in the decision matrix is shown in FIG. 3.

When the decision function for the access network selection parameter is determined as described above, a weighting vector for each access network selection parameter is determined. The weight vector W is expressed by the following [Equation 2].

W = (w ₁ , w ₂ ,…, w _m )

Where w _j is the fuzzy weight of the access network selection parameter C _j (j = 1, 2, ... m). This is represented by a set of language variables of LTI (Least important), LSI (Less important), I (Important), MEI (More important), MTI (Most important), and the membership function of these language variable values is shown in FIG. As shown in the membership function of the language variable value for the weight vector according to the embodiment of the present invention.

Once the weight vector for each access network selection parameter is determined, the level of each selection parameter for the access network selection policy is selected. The level of each selection parameter for the access network selection policy is defined as shown in Table 1 below. Levels 1 through 6 are set for each of the access network selection parameters, providing a number assigned appropriately for each level.

Since the minimum communication cost among the access network selection parameters satisfies the selection condition, the level of access network selection level 1 indicates that the communication cost is minimized, and the allocated value is high. On the other hand, in the case of user device preference, the selection condition is satisfied as the preference is maximized. Therefore, when the access network selection level is level 1, the user device preference is the highest, and the allocated value is the highest. Able to know.

Access network selection parameters Access network selection level A narrative representation Assigned number Communication cost (C) C ₁ very cheap 10 C ₂ Cheap 6 C ₃ It is suitable 3 C ₄ Somewhat expensive One C ₅ expensive 0.5 C ₆ Very expensive 0.2 User device affinity (P) P ₁ Especially preferred 10 P ₂ Very preferred 6 P ₃ Prefer 3 P ₄ is average 2 P ₅ Don't prefer One P ₆ Not very preferred 0.5 User preferred QoS (Q) based on E2E QoS Q ₁ Especially excellent 10 Q ₂ Very good 8 Q ₃ great 5 Q ₄ It is suitable 2 Q ₅ Somewhat dissatisfied One Q ₆ Dissatisfied 0.5 Access network load (L) L ₁ Very few 10 L ₂ little 6 L ₃ is average 3 L ₄ many One L ₅ Very many 0.5 L ₆ Especially many 0.2

As described above, when the level of each selection parameter for the access network selection policy is selected, the membership function value for the level of the access network selection policy and the access network selection parameter is determined, and the membership function value at this time is shown in Table 2 below. Is defined as Variables representing degree of belonging are divided into L (Low), M (Medium), MLH (More or Less high), H (High), and VH (Very High). The appropriate degree of belonging will be determined.

When the membership function value for the level of the access network selection parameter is determined as follows, the degree of fuzzy membership for each access network selection policy and the access network selection parameter is determined. The degree of belonging for each access network selection parameter is calculated by Equation 3 below.

Access network selection parameters Access network selection level Member function value L M MLH H VH Communication cost (C) C ₁ 0 0 0 0.5 1.0 C ₂ 0 0 0.5 1.0 0.5 C ₃ 0 0.3 0.7 0.5 0 C ₄ 0 0.3 0.5 0 0 C ₅ 0.5 0.5 0 0 0 C ₆ 1.0 0 0 0 0 User device affinity (P) P ₁ 0 0 0 0.5 1.0 P ₂ 0 0 0.5 1.0 0.5 P ₃ 0 0.5 1.0 0.5 0 P ₄ 0 0.5 0.5 0 0 P ₅ 0.5 0.5 0 0 0 P ₆ 1.0 0 0 0 0 User preferred QoS (Q) based on E2E QoS Q ₁ 0 0 0 0 1.0 Q ₂ 0 0 0 1.0 0.5 Q ₃ 0 0.5 1.0 0.5 0 Q ₄ 0 0.5 0.5 0 0 Q ₅ 0.5 0.5 0 0 0 Q ₆ 1.0 0 0 0 0 Access network load (L) L ₁ 0 0 0 0 1.0 L ₂ 0 0 0 1.0 0.5 L ₃ 0 0.5 1.0 0.5 0 L ₄ 0 0.5 0.5 0 0 L ₅ 0.5 0.5 0 0 0 L ₆ 1.0 0 0 0 0

Where i is an access network selection policy, j is an access network selection parameter, n is a language variable value indicating degree of membership, R _ijn is a fuzzy number for the level of access network selection policy i and access network selection parameter j, and P _ijn is Represents a membership function value for the level of the access network selection policy i and the access network selection parameter j.

Next, the weighted membership function value for the access network selection policy is determined by considering the relative importance of the degree of belonging of the calculated access network selection parameter. A weighted average method is used as a method for integrating the degree of belonging of each access network selection parameter, and the weighted degree of belonging of the access network selection policy is calculated by Equation 4 below.

In Equation 4, R _ij is the fuzzy number for the degree of belonging of the access network selection policy i and the access network selection parameter j and W _j is the fuzzy importance for the access network selection element j. Where R _ij = (o _ij , p _ij , q _ij , r _ij ), W _j = (a _j , b _j , c _j , d _j ).

(A_i, B_i, C_i, D_i)로 정의하고, 각 퍼지 선택 정책 평가치 파라미터 (A_i, B_i, C_i, D_i)들에 상기 [수학식 2]에 의해 연산된 사다리꼴 퍼지값인 다음 [수학식 5] 내지 [수학식 8]과 같은 근사 공식을 적용한다.Access fuzzy comprehensive selection of network selection policy, policy evaluation value F _i a i Fi

The trapezoidal calculated by the Equation (2) to (A _i, B _i, C _i, D _i) as defined, and each fuzzy selection policy evaluation value parameter (A _i, B _i, C _i, D _i) Approximation formulas such as the following [Equations 5] to [8] which are fuzzy values are applied.

When the weighted membership function value for the access network selection policy is determined as described above, the membership degree ranking for the access network selection policy is determined by using a generalized mean value (GMV) method to rank the membership degree fuzzy set. . The equation for GMV for weighted membership degree F _i is given by Equation 9 below.

A value with a high GMV is preferentially selected because the GMV has a higher rank of belonging to the access network selection policy than a value with a low GMV.

Although the present invention has been shown and described with reference to preferred embodiments as described above, it is not limited to the above-described embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

In the heterogeneous network of the present invention, an access network selection method using a fuzzy multi-criteria decision-making method provides subscribers with freedom of mobility as well as access network selection in a heterogeneous network environment composed of heterogeneous access networks, and provides wireless infrastructure resources to operators. It has the effect of effectively managing it.

Claims (10)

A method of selecting an access network for an end user to receive a service from an application service provider on a heterogeneous network composed of heterogeneous systems running with different protocols, (a) selecting an access network based on an access network selection parameter that satisfies a basic condition parameter determined by the application service provider based on context information composed of the end user information and terminal information of the end user; And (b) using a multi-critical fuzzy decision method including a predetermined access network selection policy to determine priority of the access network selection parameter on the user side and the system side and the access network selection parameter among the selected access networks; Steps to select the optimal access network by performing the main selection steps Method of selecting an access network using a fuzzy multi-criteria decision method comprising a. The method of claim 1, And the access network selection parameter comprises static and dynamic information, which is information between the mobile terminal and the access network. The method of claim 2, The static information includes a device side configured of authentication information of the access network, an application type executable in the mobile terminal, a QoS request level of the application, a communication cost level, and a mobile speed limit of the mobile terminal, and using the mobile terminal. And a user side configured with the user's access network preference and the user's preferred QoS level for the application. The method of claim 1, In the step (a), the basic condition parameter for selecting an access network may include: received signal strength of the mobile terminal, whether the mobile terminal authenticates with the access network, whether the mobile terminal can support the application service, and A method of selecting an access network using a fuzzy multi-criteria decision-making method, comprising a moving speed limit of a mobile terminal and whether or not resources are available in the access network. The method according to any one of claims 1 to 4, In step (b), the method of selecting an optimal access network may include: (1) determining a decision function and weight vector for applying to the access network selection parameter; (2) selecting a level of the access network selection parameter in consideration of the access network selection policy; (3) determining a membership function value and a fuzzy membership degree for the access network selection parameter and the level of the access network selection policy; (4) determining a weighted membership function value for the access network selection policy; (5) determining a priority of access network selection by determining a generalized mean value (GMV) from the degree of belonging of the determined weighted membership function; And (6) selecting an access network based on the determined access network selection priority Method of selecting an access network using a fuzzy multi-criteria decision method comprising a. The method of claim 5, The access network selection parameter includes access cost, user device preference, access network load, and user preference QoS based on end-to-end QoS. Way. The method of claim 5, The fuzzy affiliation degree is the access network selection policy, the access network selection parameter, a language variable value indicating the affiliation degree, the fuzzy number for the access network selection policy and the level of the access network selection parameter, and the access network selection policy and the A method of selecting an access network using a fuzzy multi-criteria decision-making method, which is calculated by a membership function value for the level of an access network selection parameter. The method of claim 5, The weighted membership function value for the access network selection policy is calculated as a fuzzy number for the degree of belonging of the access network selection policy and the access network selection element and a fuzzy importance for the access network selection element. A method of selecting an access network using a multicriteria decision making method. The method of claim 5, In order to determine the decision function of step (1), a decision matrix represented by a language variable set of VP (Very Poor), P (Poor), F (Fair), G (Good), or VG (Very Good) is used. A method of selecting an access network using a fuzzy multi-criteria decision-making method, characterized in that. The method of claim 5, The weight vector is represented by a set of language variables of LTI (Least Important), LSI (Less Important), I (Important) MEI (More Important), or MTI (Most Important). How to choose an access network.

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