KR101276607B1 - Apparatus and method of access system selection for heterogeneous wireless environment - Google Patents

Abstract

An object of the present invention is to provide a method and apparatus for selecting an optimal access system using an access system search procedure in a heterogeneous access system.

To this end, the apparatus according to an embodiment of the present invention, the CPC specific module for receiving the configuration information of the access systems, the frequency allocation information and the load of the access systems disposed in the wireless network from the CPC (CPC) server, A reconfiguration manager that controls an access system specific module to be reconfigured to communicate with one or more of the access systems, observe a quality of service (Qos) measured in the currently connected and serviced access system, and And a control unit for searching for and selecting an access system having the highest score using the placement information, the frequency allocation information, and the load degree to provide a corresponding service when the quality of the PC falls below a predetermined threshold value. Activate the module corresponding to the access system selected by The access system specific module to access the selected access system to provide a service.

Access system, multi-property, handover, heterogeneous network

Description

APAPATUS AND METHOD OF ACCESS SYSTEM SELECTION FOR HETEROGENEOUS WIRELESS ENVIRONMENT}

The present invention relates to a method and apparatus for selecting an access system in a wireless communication system, and more particularly, to a method and apparatus for selecting an access system in a heterogeneous wireless communication system.

A wireless communication system is a communication system using a space as a transmission medium. A communication system is a communication system in which a transmitting side carries an information signal on an electromagnetic wave to radiate it into a space and a receiving side detects an original signal by receiving an electromagnetic wave transmitted through the space. The wireless communication system is largely divided into fixed communication in which transmission / reception positions are fixed and mobile communication in which one side moves. In the past, fixed communication such as microwave was the majority of wireless communication, but as the society develops gradually, mobile communication that can communicate with anyone anytime, anywhere is gaining great attention.

The wireless communication system has a cell structure in which a number of access systems are overlaid with the development of technological breakthroughs, providing higher quality services to users and providing access networks of operators. Is evolving into a more efficient use of. BWA (Broadband Wireless Access or WiMAX) based on 3rd Generation Partnership Project (3GPP) and 3GPP2 based mobile communication system and Institute of Electrical and Electronics Engineers (IEEE) for interworking between heterogeneous access systems of this type. And the Wireless Local Access Network (WLAN) standard is conducting additional research and standardization work.

Currently, various types of solutions for interworking and handover between heterogeneous wireless communication systems have been proposed, and each solution is standardized by standardization organizations. As an interworking method proposed by 3GPP, Voice Call Continuity (VCC) using I-WLAN, GAN (Generic Access Network), and IMS (IP Multimedia System) has been proposed. I-WLAN proposes interworking method and structure between 3GPP system and WLAN and standardizes billing integration function, but handover and interworking methods are integrating with GAN and VCC methods. GAN is a specification that integrates the Unlicensed Mobile Access (UMA) solution into the 3GPP specification to support handover between Global System for Mobile Communication (GSM) and WLAN. VCC is a solution using IMS to guarantee mobility between the CS (Circuit Service) domain and the PS (Packet Service) domain, and the specification is defined in 3GPP Release7.

On the other hand, the IEEE is proceeding standardization for interworking with different access systems such as IEEE system and mobile communication system through IEEE 802.21. Currently, IEEE 802.21 aims to provide seamless handover between heterogeneous access networks with the purpose of MIH (Media Independent Handover). In addition, standards for handover scenarios such as WLAN (IEEE 802.11 series), BWA (IEEE 802.16 series), and IEEE series such as IEEE 802.3, and mobile communication systems such as 3GPP and 3GPP2 are being developed. In particular, IEEE 802.21 performs the standardization of the structure and function of MIH, the standard for event / information / trigger service, and the handover procedure between heterogeneous networks.

The E2R (End to End Reconfigurability) project presented a Cognitive Pilot Channel (CPC) that can dynamically allocate information and broadcast information of a deployed system in a wireless network in which multiple heterogeneous wireless systems are deployed. The implementation method of CPC proposed by E2R can be divided into Out-band CPC or In-band CPC. Out-band CPC provides a CPC service using a specific frequency channel that can transmit CPC information exclusively. In-band CPC provides a CPC service using a channel of an existing wireless communication system.

In a conventional homogeneous access environment, a handover connects to a target access system according to Received Signal Strength (RSS), threshold, and DT (Dwell Time). Method was used. However, in case of handover between heterogeneous access systems, the cost of channel change and handover is high. Therefore, not only the parameters considered in the homogeneous access environment but also various parameters such as user requirements and the environment of the access network are used. Handover must be determined.

Accordingly, the present invention provides a method and apparatus for selecting an access system higher than a threshold using an access system discovery procedure in a mobile network environment in which heterogeneous access systems are mixed.

An apparatus according to an embodiment of the present invention, in the access system selection device, CPC for receiving the configuration information of the access systems arranged in the wireless network, the frequency allocation information and the load of the access systems from the CPC (CPC) server Observe a particular module, a reconfiguration manager that controls the access system specific module to be reconfigured to communicate with one or more of the access systems, a quality of service (Qos) measured in the currently connected and serviced access system, A control unit for searching for and selecting an access system having the highest score using the arrangement information, the frequency allocation information, and the load degree to provide the service when the quality of the observed service falls below a predetermined threshold value; To an access system selected by the control unit. And the access system specific module for activating a corresponding module to access the selected access system and provide a service.

In accordance with an aspect of the present invention, a method of selecting an access system includes: receiving, from a CPC server, configuration information of access systems disposed in a wireless network, frequency allocation information, and load level of the access systems; Wow; Measuring the quality of service (Qos) of the currently accessed and serviced access system; and when the quality of the measured service falls below a predetermined threshold, the arrangement information and the frequency allocation information to provide a corresponding service. And searching for and selecting an access system having the highest score using the load level, and reconfiguring a wireless unit to communicate with the selected access system.

According to the present invention, the quality of service (QoS) is guaranteed compared to the method based on the received signal strength by receiving the service by selecting the access system based on the multiple attributes that the user can recognize. This service is easy and adapts to communication environment.

The above objects, features, and advantages will be described in detail with reference to the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, it is to be noted that each of the terms described below are merely used to help the understanding of the present invention, and may be used in different terms despite the same purpose in each manufacturing company or research group. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing an interworking structure of a wireless communication access system according to an embodiment of the present invention.

In FIG. 1, an access system (hereinafter referred to as an 'AS') is a 3GPP mobile communication base station 106, a home eNodeB 109 of a long-term evolution (LTE) of 3GPP, a base station of a Wimax (hereinafter, ' For example, the BS 110 may be referred to as an access point 112, an WiFi access point (hereinafter referred to as an AP) 112, or the like. In addition, due to the development of the access system, the base station not only provides a predetermined service, but also includes a reconfigurable base station 120 for reconfiguring according to a situation to enable another radio access service, and the CPC base station 122 providing CPC information. This can be installed.

In addition, the base station (BS) or access point (AP) illustrated in FIG. 1 as well as the base station (BS) or access point (AP) of another wireless communication system can be applied when the operation is possible in accordance with the spirit of the present invention. have. Therefore, the present invention is not limited to the example illustrated above.

The 3GPP mobile communication base station 106, which is a mobile communication system equipment to which a mobile terminal wirelessly connects, is connected to a mobile communication provider network. The 3GPP mobile communication base station 106 may simply indicate to the NodeB 108 and the RNC 107.

NodeB 108 refers to a generic base station as a name for a base station in 3GPP. The NodeB 108 can reduce infrastructure construction costs from the base station to the control station by using a DSL (Digital Subscriber Loop) network to access the mobile communication network, and design various additional service functions in connection with the network system. Can be. NodeB 108 may have several cells, each of which has carriers used in its own cell. The NodeB 108 is connected to many user equipments (hereinafter referred to as UEs) 130 existing in the cells, and secures frequencies used in the cell. The Radio Network Controller (RNC) 107 is connected to the top of the NodeB 108, and not only controls the NodeB 108, but also allocates communication resources or performs handover, radio bearer (RB). Assign. The 3GPP mobile communication base station 106 is based on 3G W-CDMA.

The eNodeB 109 of Long-Term Evolution (LTE), which means an evolutionary access network and an evolutionary core network within 3GPP, is in progress of standardization and will communicate in a manner determined according to the standardization. The eNodeB 109 is a form in which the existing NodeB 108 and the RNC 107 are integrated, and all the protocol layers mounted in the existing RNC 107 are included in the eNodeB 109.

WiMAX BS 110 and WiFi AP 112 are capable of internet connection data communication, such as wireless LAN, but voice communication such as mobile phones.

Each of the systems described above (reference numerals 106, 109, 110, 112) corresponds to an AS. In addition, the AS may include a reconfigurable base station 120 for reconfiguring a base station according to the development of an AS to enable service and a CPC base station 122 for providing CPC information.

In FIG. 1, reference numeral 140 illustrates various types of AS cells, and is assumed to be a cell by a base station of another system according to the shape of each illustrated cell. For example, reference numeral 142 denotes an eNodeB service network for 3G LTE service, and reference numeral 144 denotes a BS service network of WiMAX.

Heterogeneous AS handover is a cell change to a different type of AS from a currently serving AS, for example, when a handover is performed from an eNodeB 142 service network to a BS 144 service network of WiMAX.

Homogeneous AS handover is to change a cell to an AS of the same type as the currently serviced AS, for example, when handing over to an eNodeB 146 service network connected to a system having the same protocol in an eNodeB 142 service network. Is applicable.

In the above, the example of the AS has been described. Next, the interworking structure of the wireless communication AP will be described in detail.

In the present invention, a multimode terminal based on a CPC server (102) for providing deployment information of an AS and a software defined radio (SDR) and performing a CPC client function is considered. The multi-mode terminal means the UE 130. The UE 130 is an SDR-based reconfigurable multimode terminal and has a wide range of universal access. Herein, universal access refers to a multi-mode terminal in which the UE 103 is reconfigurable based on SDR, selects a specific AS available through the AS discovery, and communicates inside the UE 103 associated with the selected specific AS. Reconfigure the module to connect to the AS. The UE 130 has hardware that supports modules such as WCDMA, WiMAX, WiFi, etc., and provides a service through interworking with a specific AS.

The CPC server 102 manages the frequency allocation information, the load degree of the AS and the placement information of the AS dynamically in association with the Spectrum Broker 100 and the Cognitive Radio Resource Manager (CRRM) 104. . The spectrum browser 100 is responsible for dynamically assigning frequencies and assigning ASs according to the operator's request and policy, and transmits frequency allocation information of the ASs to the CPC server 102. The CRRM 104 is a functional entity that performs a radio resource management function of a plurality of ASs. In the present invention, the load level of each AS is measured, and the load level of the AS 130 is again transmitted through the CPC server 102 or the AS 130. ) To broadcast to. The CPC server 102 periodically broadcasts the frequency allocation information provided by the spectrum browser 100, the load degree of each AS provided by the CRRM 104, and the arrangement information of the AS set by the operator using the CPC. The UE 130 periodically receives the allocation information and the frequency allocation information of the AS to obtain information of the available AS, and selects the AS in consideration of service requirements and various parameters according to the received AS information.

As described above, the CPC server 102 is a server having a database for managing the placement information of the wireless communication AS, the frequency allocation information, and the load of each AS, which the operator presents, and the placement of the wireless communication AS to the UE 130. Provide information. Looking at the information provided by the CPC server 102 according to an embodiment of the present invention, for example, as shown in Table 1 below, the information is periodically transmitted to the UE (130).

Access system information Explanation Operator -Operator ID Frequency band
(Frequency Band) Assigned frequency band Access system type
(AS Type) -Radio Access Technology Type
Version Information Cell radius
(Cell Radius) Location Info: Location information of the deployed cell (eg NMEA-based coordinate information)
Cell Radius: service radius of deployed cell
Adjacent Cell List AS load accuracy
(AS Load) -Load level of each AS provided by CRRM

Since the arrangement information of the AS in the <Table 1> is the AS managed by the service provider, the service provider can provide the service effective radius, the location of the neighboring cell, the type of the AS, etc. It can be seen. In addition, when there is an agreement between the operators, the information of the AS serviced by different operators can also be known by exchanging the arrangement information of the AS between the operators.

2 is a functional block diagram of a user device according to an embodiment of the present invention.

It should be noted that the UE according to the present invention is a configuration for a wide range of accesses, and excludes general functions, for example, functional blocks such as a key input unit, a display unit, a battery, and the like.

The UE includes a user subscription information module (USIM) 200, a controller 220, a reconfiguration manager 204, an AS specific module 206, a GPS module 208, and a CPC specific module ( 210, memory 212.

The USIM 200 stores user identification information and preference information of an AS preset by the user. In addition, the USIM 200 may store execution programs according to the type of AS serviced.

The controller 220 not only controls all functional blocks of the UE, but also performs a search and selection function of an AS for a service in an environment in which a plurality of ASs are linked. The control unit 220 measures the received signal strength of the AS serviced by the UE and the movement speed information of the UE, and the AS configuration information and frequency allocation information of the AS periodically transmitted from the CPC server 102 and the load degree of each AS It is provided.

The AS selection process starts when the quality of service (hereinafter referred to as 'QoS') measured by the AS that is being connected to is degraded.The AS selection process is performed by selecting an AS that satisfies the QoS of the service. do. The controller 220 continuously monitors the QoS of the services measured in the currently connected and serviced AS, and if the observed QoS falls below a certain threshold, the controller 220 selects the AS and channel having the highest score for the corresponding service. Perform the procedure to select. The AS selection procedure of the UE will be described later with reference to FIG. 3.

AS Specific Module 206 consists of hardware and software capable of supporting all modules such as WCDMA, WiMAX, WiFi, and the like. The AS specific module 206 is connected to the antenna 205 and transmits and receives data or signals or data and signals with the selected specific AS through the antenna 205. The AS specific module 206 may turn on the module corresponding to the AS selected by the controller 220 to access the AS and receive a service. In addition, the controller 220 checks the received signal strength RSS in the data received by the AS specifying module 206 to determine whether the channel is in a serviceable state.

The reconfiguration manager 204 downloads a program of the AS from the USIM 200 or an operator server (not shown) to communicate with the specific AS selected by the controller 220, and sets a communication module associated with the selected specific AS. And control. The reconfiguration manager 204 may be implemented by being included in the controller 220.

The GPS module 208 provides Location Based Service (LBS) and location information, and may be selectively used according to a user's needs.

The CPC specifying module 210 receives and processes out-band CPC information through the antenna 209 that broadcasts information of a system arranged in a wireless network using a specific frequency channel, and transmits it to the controller 220. The load degree of the AS may be received through the CPC specific module 210 or the AS specific module 206.

The memory 212 stores a program and a control program necessary for the execution of the UE, and transfers the corresponding program at the request of the controller 220.

3 is a flowchart illustrating an access system selection procedure in a user terminal according to an embodiment of the present invention.

The AS selection procedure starts when the QoS measured by the currently connected AS is degraded. The AS selection procedure is performed by selecting an AS that satisfies the QoS of the service.

In step 302, the controller 220 continuously monitors the QoS of the services measured by the currently connected and serviced AS. In step 304, when the observed QoS falls below a certain threshold, the controller 220 performs a procedure for selecting an AS and a channel having the highest score for the corresponding service. If the observed QoS is above a certain threshold, maintain the connection of the currently serving AS.

In order to perform the procedure for accessing the AS, the controller 220 defines and uses a recommended AS set, a candidate AS set, and a valid AS set for each step. .

In step 305, the controller 220 receives the AS batch information broadcast from the CPC server 102.

The controller 220 connects to the AS having the highest score by using a utility function derived by using placement information about the ASs included in the candidate AS set, measurement information of the UE, and load of the AS. Is carried out as a procedure. The utility function will be described later with reference to FIG. 4.

In step 308, the controller 220 generates a recommended AS set based on the AS placement information received from the CPC server 102. In step 312, among the ASs generated in the recommended AS set, a candidate AS set is generated by selecting ASs having a good reception signal and being available for service. In operation 314, a valid AS set is generated by considering a movement pattern of the UE and a radius of a cell that the AS serves among candidate AS sets. In step 316, a score for a valid set of ASs is calculated using utility functions derived from the channel state of the AS, the load state of the AS, and the quality of service (QoS) required. In step 318, the controller 220 selects and connects the AS having the highest score among the valid AS sets.

Table 2 below is an example of attributes considered in the access system selection method, and the description of each attribute is also shown.

Attribute function Receive Signal Strength (RSS) Received Signal Strength
-Used to know if the channel is serviceable Cell radius / speed
(Cell Radius / Velocity) -It is used to compare the make-up time and residence time by considering the current moving speed and the size of the cell. Access system load
(AS Load) -Load of each AS
Use measurements for throughput, delay, and jitter User Preference -Priority of AS as presented by the user

), 지연(Delay)(

) 그리고 지터(Jitter)(

)에 대해서 관측절차를 수행한다. 그리고 각각의 파라메터들을 이용한 서비스에 대한 QoS 수준이 특정 임계값 이하일 경우에 제어부(220)는 AS 탐색 및 선택 절차를 수행한다.According to an embodiment of the present invention, in order to select an optimal access system, a bit rate of a received service (

), Delay (

) And Jitter (

Perform the observation procedure for). When the QoS level of the service using the respective parameters is equal to or less than a specific threshold, the controller 220 performs an AS discovery and selection procedure.

), 지연(

) 그리고 지터(

)에 대한 가중치(weight factor)를 달리하여 트래픽의 특성을 고려한다. 즉, 음성위주의 실시간 트래픽의 경우에는 지연과 지터에 높은 가중치를 부여하고, 데이터위주의 트래픽일 경우에는 비트율에 보다 높은 가중치를 부여한다. 상기 기술한 각각의 파라메터를 도출하는 방법과 해당 파라메터를 이용하여 QoS 수준을 측정하는 방법은 하기의 <수학식 1> 내지 <수학식 5>와 같다.Also, depending on the nature of the traffic,

), delay(

) And jitter (

), Consider the characteristics of the traffic by varying the weight factor. That is, in the case of voice-oriented real-time traffic, high weight is given to delay and jitter, and in the case of data-oriented traffic, a higher weight is applied to bit rate. A method of deriving each of the above-described parameters and a method of measuring the QoS level using the corresponding parameters are shown in Equations 1 to 5 below.

Table 3 below shows how to determine the current QoS in the UE using the QoS parameter variation.

then Qos degradation
Else
No QoS degradationif

then Qos degradation
Else
No QoS degradation

The AS selection method according to the present invention activates the list of recommended AS sets extracted through the AS search procedure. Here, the list refers to ASs available through searching among ASs (reference numerals 106, 109, 110, 112), and may be one or plural. The list activation means turning on a module embedded in a UE that provides a service corresponding to each AS. For example, if an AS of WiMAX is found in the list of recommended AS sets through the discovery procedure, the UE turns on a module corresponding to WiMAX among the built-in AS specific modules 206. After activating the list, the controller 220 checks whether the received received signal strength RSS is in a serviceable state. The received signal strength is a basic parameter for determining whether a service is available using the corresponding AS, and measures the received signal strength of each AS based on a measurement window as shown in FIG. 4 to be described later.

4 is an explanatory diagram for measuring received signal strength using a measurement window according to an exemplary embodiment of the present invention.

)가 해당 임계값(

)보다 높을 경우에는 해당 액세스 시스템을 후보 AS 셋에 추가한다.Each AS uses an average RSS (measurement window) within a measurement window using a predefined threshold of serviceable received signal strength.

) Is the corresponding threshold (

Higher than), add the access system to the candidate AS set.

)를 도출할 수 있다. 다음은 수신신호 강도와 관련된 파라메터들을 도출하는 방법은 하기의 <수학식 6> 내지 <수학식 8>과 같다.In addition, the size of the window used to measure the average value of the received signal strength can be set variably, and a utility function (

) Can be derived. Next, a method of deriving the parameters related to the received signal strength is shown in Equations 6 to 8 below.

Table 4 below shows an operation procedure for selecting an access system using the received signal strength of the UE.

)
then Delete the AS from the recommended set
Else
Add the AS to candidate set
Calculation of utility function at AS decisionif (

)
then Delete the AS from the recommended set
Else
Add the AS to candidate set
Calculation of utility function at AS decision

Since the UE has mobility according to the movement pattern, the cell residence time (CRT) may be predicted in consideration of the current speed of the UE and the size of the cell when performing the AS selection. However, it is impossible to have accurate information on the movement pattern of the actual UE, and it is difficult to predict the mobility of the UE. Therefore, the present invention proposes a method of applying the residence time of a cell serviced by a specific AS using the speed of the UE and the radius of the cell. That is, if the UE assumes a linear movement and does not stop while moving, it can predict the residence time of the cell based on this.

)는 정확한 값이 아니므로, 예측치는 AS를 선택하는 유틸리티 함수로는 사용하지 않으며, 새로운 셀의 접속을 위한 생성시간(Makeup Time)과 비교하여 도출된 거주시간(CRT)이 생성시간(MT)보다 클 경우에만 후보 AS 셋에 추가한다.Estimate of the derived CRT (

) Is not an exact value, so the predicted value is not used as a utility function to select an AS, and the residence time (CRT) derived from the creation time (MT) is compared with the creation time for accessing a new cell. Add to candidate AS set only if greater than

The generation time refers to a setup time required for a signaling procedure, an authentication procedure, and the like for accessing a specific AS to a UE. Equation 9 below shows a method of deriving the above-described CRT, and Table 5 below shows an operation procedure using CRT related parameters.

)
then Delete the AS from the candidate set
else
Add the AS to available setif (

)
then Delete the AS from the candidate set
else
Add the AS to available set

Since the present invention proposes a method of selecting an AS having the best score suitable for a service, a method of measuring the load of each AS is required. To measure the load on the AS, a number of parameters can be used, such as the number of users currently connected, bandwidth occupancy, delay, and delay variation.

)을 예측한다. 또한, 실시간 트래픽 및 멀티미디어 트래픽에서 중요한 인자로 고려하는 지연과 지터의 요구치와 현재 AS에서 측정된 값의 비를 비교하여 제공 가능한 지연(

) 및 지터(

)를 예측한다. 상기 기술한 파라메터들을 이용하여 AS의 부하(Load)에 대한 유틸리티 함수를 도출하고 이를 기반으로 AS의 선택 방법에 사용한다. 파라메터들의 부하정도를 예측하는 방법은 하기의 <수학식 10> 내지 <수학식 13>과 같으며, 예측된 부하정도를 이용한 유틸리티 함수(

)을 하기의 <수학식 13>과 같이 나타낼 수 있다.The present invention considers throughput, delay, and jitter to measure the degree of load on the AS. That is, in consideration of the maximum capacity of a specific AS, the throughput serviced by the current AS, and the throughput required by the UE,

). Also, delay and jitter, which are considered important factors in real-time and multimedia traffic, can be provided by comparing the ratio of the measured value of the current AS

) And jitter (

Predict Using the above-described parameters, the utility function for the load of the AS is derived and used for the selection method of the AS. The method of estimating the load degree of the parameters is shown in Equations 10 to 13 below, and a utility function using the estimated load

) Can be expressed as in Equation 13 below.

)에 적용하는 방법을 나타낸 것이다.In a wireless communication system in which a plurality of ASs work together, a user accesses an AS using a connection list that meets his or her requirements and receives a service. Therefore, in the present invention, priority is given to the ASs set by the user, and used as one parameter for AS selection. The preference information of the AS set by the user may be stored in the USIM 200 of the UE or the like, and the user may dynamically change the access priority at the initial setting. Equation 14 below converts the user's preference information to a utility function (

) Shows how to apply.

)를 계산하고, 각각의 속성에 대해서 가중치(

)를 적용한 후 AS를 위한 유틸리티 함수(

)를 계산하여 최고의 값을 갖는 AS를 선택한다.The entire utility function for AS selection based on each attribute described above is shown in Equation 15 below. That is, each AS is a utility function (for multiple attributes)

), And the weight (

), And after applying the utility functions for AS

) To select the AS with the highest value.

Table 6 below shows an operation procedure for selecting an AS having the highest score among ASs in a useful system set by using the above-described parameters and utility functions.

while (count_AS> 0)
{
Calculation of Utility function for each AS _i
}

A channel change and handover procedure between heterogeneous ASs can be broadly divided into a downward handover (hereinafter referred to as 'DH') and an upward handover (hereinafter referred to as 'UH').

DH refers to the channel change procedure from the global network or the AS with a wide service area to the AS with a local network and a narrow service area. For example, when the UE moves from the UMTS network to the WLAN network.

UH refers to a channel change procedure from an AS having a local network and a narrow service area to an AS having a global network or a wide service area. For example, when the UE moves from the WLAN network to the UMTS network.

5 is a flowchart illustrating an operation procedure for downlink handover using multiple attributes and a utility function according to an embodiment of the present invention.

5 is a channel change procedure from an AS having a global network service area to an AS having a local network service area.

Downward handoff (DH) between heterogeneous access systems begins when the QoS measured at the AS to which the UE is currently connected is degraded.

In step 501, the UE is currently registered with an AS having a global room service area. In step 503, the controller 220 operates a measurement timer (not shown). If the QoS of the service observed in step 507 falls below a certain threshold value, the controller 220 proceeds to step 509 to select an AS and a channel having the highest score for the service.

If the QoS of the service observed in step 507 is greater than or equal to a certain threshold value, the process returns to step 501 to maintain the current AS.

In step 509, the controller 220 receives the AS batch information broadcasted periodically from the CPC server 102 to generate a recommended AS set, and among the ASs generated in the recommended AS set, those with a good reception signal and service are available. Choose.

In step 513, the AS specific module 206 embedded in the UE activates a module corresponding to the available AS selected in step 509. For example, if the eNodeB 109 and the BS 110 are selected among the recommended AS set in step 509, the AS specific module 206 activates the modules corresponding to the eNodeB 109 and the BS 110. If the specific module is activated, the process proceeds to step 515, and the controller 220 evaluates the received signal strength RSS received by the specific module. In step 517, the controller 220 evaluates the received signal strength to determine whether the received signal strength is greater than or equal to a predetermined threshold. That is, it is checked whether the slope of the received signal strength is greater than zero and greater than a specific threshold. If the received signal strength is greater than or equal to a predetermined threshold, the controller 220 proceeds to step 519 and the controller 220 adds the currently connected AS to the candidate AS set.

In step 521, the controller 220 checks the state of the candidate AS set. The controller 220 determines whether there is a candidate AS set available in consideration of a movement pattern of the UE and a radius of a cell served by the AS. If there is no candidate AS available in step 521, the process returns to step 501 and proceeds again.

If there is a available candidate AS, the controller 220 proceeds to step 523 and determines whether the number of candidate AS sets is greater than zero. If there is no candidate AS set, the process returns to step 501 and proceeds in turn.

If there is a candidate AS available, the controller 220 proceeds to step 525 and the controller 220 estimates a time (CRT) in which the UE resides in the cell. Since the UE has mobility according to the movement pattern, when the AS selection is performed, the residence time (CRT) of the cell may be estimated in consideration of the current speed of the UE and the size of the cell.

In step 529, the make-up time for accessing the new cell is compared with the derived residence time (CRT) of the cell. If the time in which the UE resides in the cell (CRT) is greater than the generation time (MT), the process proceeds to step 531 to add the AS to which the current UE belongs to the valid AS set.

If the time in which the UE resides in the cell (CRT) is less than the generation time (MT), the UE proceeds to step 527 to turn off a specific module corresponding to the current candidate AS set. In step 523, the controller 220 checks whether another candidate AS set exists, and if so, proceeds in the above-described order. If no junior AS set exists, go back to step 501 and start again from the beginning.

If the controller 220 adds a valid AS set in step 531, the controller 220 proceeds to step 540 to determine whether there is a valid AS available. If there is no valid AS, the control unit 220 returns to step 501 and proceeds in order from the first step.

If there is a valid AS in step 540, the controller 220 proceeds to step 542 by using a utility function derived from the received signal strength, the load of the access system, and the preference of the AS preset by the user. Calculate Score.

In step 544, the controller 220 selects an AS having the highest score, and the AS specific module 206 activates a module corresponding to the selected available AS and connects to the selected AS. After the controller 220 accesses the selected AS and registers with the AS in step 546, the controller 220 performs downward handover.

FIG. 6 is a flowchart illustrating an operation procedure for upward handover using multiple attributes and a utility function according to an embodiment of the present invention.

FIG. 6 relates to a channel change procedure from an AS where a UE has a local network service area to an AS having a global network service area.

Upward handoff (UH) between heterogeneous ASs starts when the QoS measured at the AS to which the UE is currently connected is degraded.

In step 601, the UE is currently registered with an AS having a local room service area. In step 603, the controller 220 operates a measurement timer (not shown).

In step 605, the controller 220 continuously observes the QoS state of the UE currently being serviced, and checks whether the QoS of the observed service falls below a specific threshold. If QoS is above a certain threshold, no handover is performed and the service of the current AS is maintained.

If the QoS of the service falls below a certain threshold, the controller 220 proceeds to step 607. In step 607, the controller 220 receives the AS batch information periodically broadcast from the CPC server 102 to generate a recommended AS set, and an AS capable of receiving a good signal and providing a good service among the access systems generated by the recommended AS set. Select them.

In step 609, the controller 220 checks whether an AS of the same type exists among the searched ASs. If there is a homogeneous AS, the flow proceeds to step 611 to select an homologous AS. That is, if the currently registered AS belongs to the WLAN area, the handover is performed to the same WLAN area of the searched AS. If the same type AS is selected, the controller 220 proceeds to step 613 to perform the same type handover connection procedure.

If the same type of AS does not exist in step 609, the control unit 220 turns on a specific module corresponding to the heterogeneous AS searched by the control unit 220. If the specific module is activated, in step 617, the controller 220 evaluates the received signal strength RSS received at the AS associated with the specific module. In step 619, the controller 220 checks the received signal strength to determine whether the received signal is greater than or equal to a predetermined threshold. That is, it is checked whether the slope of the received signal strength is greater than 0 and greater than a specific threshold.

If the received signal strength is less than or equal to a predetermined threshold in step 619, the control unit 220 returns to step 615 to correspond to an AS having a good and good service among other ASs generated in the recommended AS set. Activate a specific module and evaluate the received signal strength again. If the received signal strength is greater than or equal to a certain threshold, the controller 220 proceeds to step 621 and adds the candidate AS set.

In step 623, the controller 220 checks the candidate AS state. The controller 220 checks whether there is a candidate AS available in consideration of a movement pattern of the UE and a radius of a cell served by the AS. If there is a candidate AS available in step 623, the flow proceeds to step 631, and the controller 220 checks whether the number of AS sets is greater than zero. If the candidate AS exists, the process proceeds to step 633 to estimate the time (CRT) the UE is inhabiting the cell. Since the UE has mobility according to the movement pattern, when the AS selection is performed, the residence time (CRT) of the cell may be estimated in consideration of the current speed of the UE and the size of the cell. In operation 637, the generation time MT for accessing the new cell is compared with the derived residence time CRT of the cell. If the time in which the UE resides in the cell (CRT) is smaller than the generation time (MT), the controller 220 removes the candidate AS set available in step 639 and proceeds to step 635 to correspond to the current candidate AS set. After the specific module is turned off, the process proceeds to step 631. In addition, if the time in which the UE resides in the cell (CRT) is greater than the generation time (MT), the UE proceeds to step 641 to add to the valid AS set.

If the controller 220 adds a valid AS set in step 641, the controller 220 determines whether there is a valid AS available in step 643. If there is no valid AS in step 643, the controller 220 proceeds to step 625 and checks preference information of the AS set by the user. In operation 627, the controller 220 turns on a specific module corresponding to the global network, and proceeds to operation 629 to perform an access procedure.

In addition, if there is no candidate AS available in step 623, the process proceeds to step 625 to perform steps 627 and 629 in the same manner as described above.

If there is a valid AS in step 643, the controller 220 proceeds to step 645 and the control unit 220 scores using a utility function derived from a received signal strength, an AS load level, and preference information preset by the user. Calculate In step 647, the controller 220 selects an AS having the highest score, and the AS specific module 206 activates a module corresponding to the selected available AS and performs a procedure of accessing the selected AS. The controller 220 performs upward handover by registering with the AS in step 649 after performing the procedure of accessing the selected AS.

1 is a view showing an interworking structure of a wireless communication access system according to an embodiment of the present invention.

2 is a functional block diagram of a user device according to an embodiment of the present invention.

3 is a flowchart illustrating an access system selection procedure in a user terminal according to an embodiment of the present invention.

4 is an explanatory diagram for measuring received signal strength using a measurement window according to an exemplary embodiment of the present invention.

5 is a flowchart illustrating an operation procedure for downlink handover using multiple attributes and a utility function according to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation procedure for upward handover using multiple attributes and a utility function according to an embodiment of the present invention.

Claims (10)

An access system selection device, A CPC specific module for receiving configuration information of the access systems arranged in the wireless network, the frequency allocation information and the load of the access systems from the CPC server; A reconfiguration manager for controlling an access system specific module to be reconfigured to communicate with one or more of the access systems; Observe the quality of service (Qos) measured in the currently accessed and serviced access system, and when the quality of the observed service falls below a predetermined threshold, the batch information and the frequency allocation information to provide a corresponding service. And a controller for searching for and selecting an access system having the highest score using the load degree. The access system specific module for activating a module corresponding to the access system selected by the controller to access the selected access system and provide a service; Access system selection device comprising a. The method of claim 1, wherein the CPC specific module, And access band CPC information using a specific frequency channel. The method of claim 1, wherein the reconfiguration manager, Downloading the program of the selected access system from an operator server and controlling the access system specific module associated with the selected access system to be reconfigured. The method of claim 1, And a USIM for storing identification information of a user and priority information of the access systems preset by the user. The method of claim 1, An access system selection device further comprising a GPS module for providing location based services and location information. The method of claim 1, And a memory in which programs and control programs necessary for execution of the user device are stored. The method of claim 1, wherein the searching of the access system having the highest score by the controller comprises: Create a set of recommended access systems based on the information received from the CPC server, Selecting a candidate access system set of which the received signal is good and serviceable among the generated recommended access systems, The residence time of the cell is estimated in consideration of the current speed of the user equipment and the size of the cell in the selected candidate access system set, and the residence time of the predicted cell is compared with the generation time for accessing a new cell. And generating a valid set of access systems if the residence time of the cell is greater than the generation time, and then searching for the access system with the highest score using a utility function. The method of claim 7, wherein the searching for the access system having the highest score comprises: An access system for searching for the access system with the highest score using a utility function derived from a channel condition, an access system load condition, and a service request required for selecting the access system with the highest score in the selected candidate access system set; Optional device. In the access system selection method, Receiving deployment information of the access systems arranged in the wireless network, frequency allocation information and the load of the access systems from a CPC server; Measuring a quality of service (Qos) of an access system currently connected and serviced; If the quality of the measured service falls below a predetermined threshold, searching for and selecting an access system having the highest score using the placement information, the frequency allocation information, and the load degree to provide the service; , Reconfiguring a radio to communicate with the selected access system Access system selection method comprising a. The method of claim 9, wherein searching for the access system having the highest score comprises: Generating a set of recommended access systems based on the information received from the CPC server; Selecting a candidate access system set having a good reception signal and being available for service among the generated recommended access systems; The residence time of the cell is estimated in consideration of the current speed of the user equipment and the size of the cell in the selected candidate access system set, and the residence time of the predicted cell is compared with the generation time for accessing a new cell. And generating a valid set of access systems if the residence time of the cell is greater than the generation time, and then searching for the access system with the highest score using a utility function.

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