JP2010252335A - Method and device for selecting access system in heterogeneous radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for selecting an optimum access system, in a heterogeneous access system. <P>SOLUTION: A user device (UE) is connected to a homogeneous and/or heterogeneous access system in an environment where a plurality of access systems are interlocked with one another. The UE includes: an access system identification module for activating a module corresponding to an access system to be connected to the access system, and providing a service; a CPC identification module for receiving, from a CPC server, information of respective access systems arranged in a wireless network, frequency allocation information of each access system, and the level of a load; a reconfiguration manager for controlling the access identification module to be reconfigured for communicating with one of the access systems; and a control part for observing Qos measured by an access system that is currently connected and served, and retrieving an optimum access system for the service to be thereafter selected when the Qos is below a predetermined threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an access system selection method and apparatus 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 that uses space as a transmission medium, and radiates information signals on the electromagnetic wave from the transmission side to the space, and the reception side receives the electromagnetic wave transmitted through the space and detects the original signal. It is a communication system of the system to do.

  Wireless communication systems are broadly classified into fixed communication in which the position of transmission / reception is fixed and mobile communication in which one moves. Conventionally, fixed communication such as microwaves has been a major part of wireless communication, but as society develops, mobile communication that can communicate with anyone at any time and anywhere has attracted much attention.

  The wireless communication system has a cell structure in which a plurality of access systems are overlaid with the breakthrough technological development, and provides higher quality services to users. As a result, the network has evolved into a form that efficiently uses the access network of the operator. In order to link such heterogeneous access systems, mobile communication systems based on 3GPP (3rd Generation Partnership Project) and 3GPP2 and BWA (Broadband based on Institute of Electrical and Electronics Engineers) are used. Additional research and standardization work is being done on the Wireless Access: WiMAX) and WLAN (Wireless Local Access Network) standards.

  Currently, various forms of solutions for interworking and handover between different types of wireless communication systems are presented, and each solution is being standardized by a standards body. Interlocking methods presented in 3GPP are roughly classified into I-WLAN, GAN (Generic Access Network), and VCC (Voice Call Continuity) using IMS (IP Multimedia Subsystem). Although I-WLAN is proposing standardization for the billing integration function by proposing a linkage method and structure between the 3GPP system and the WLAN, the handover and the linkage method tend to be integrated with the GAN and VCC methods. GAN is a standard in which a UMA (Unlicensed mobile Access) solution for supporting a handover between a GSM (Global System for mobile Communication) and a WLAN is integrated into the 3GPP standard. VCC is a solution that uses IMS to ensure mobility between a CS (Circuit Service) domain and a PS (Packet Service) domain, and a standard is defined in 3GPP Release7.

  In comparison, IEEE 802.21 is proceeding with standardization for linking different access systems such as IEEE systems and mobile communication systems. Currently, IEEE 802.21 has a purpose of MIH (Media Independent Handover) and aims to provide seamless handover between different types of access networks. Standards for handover scenarios with WLAN (IEEE 802.11 series), BWA (IEEE 802.16 series), and IEEE series handover scenarios such as IEEE 802.3 and mobile communication systems such as 3GPP and 3GPP2 Is progressing. In particular, IEEE 802.21 carries out standardization work for MIH structure and function, standards for events / information / trigger services and handover procedures between different networks. Yes.

  In the E2R (End to End Reconfigurability) project, dynamic spectrum allocation is possible, and CPC (Cognitive Pilot Channel, Common Pilot Channel) capable of broadcasting information on systems arranged in a wireless network in which a plurality of different types of wireless systems are arranged. Presented. The implementation method of CPC presented in E2R can be divided into Out-band CPC or In-band CPC. Out-band CPC is a form in which a CPC service is provided using a specific frequency channel capable of transmitting CPC information exclusively. In-band CPC is a CPC using a channel of an existing wireless communication system. This is a form of providing a service.

  The existing Homogeneous access environment is connected to a target access system according to received signal strength (hereinafter referred to as “RSS”), threshold (Threshold), and DT (Dwell Time). The handover method was used. However, since handover between different access systems requires a lot of cost for channel change and handover, not only the parameters considered in the same kind of access environment, but also user requirements and access network environment The handover must be determined based on various parameters.

  An object of the present invention is to provide a method and apparatus for selecting an optimum access system using an access system search procedure in a mobile network environment in which different types of access systems are mixed.

  An apparatus according to an embodiment of the present invention is a user equipment (UE) for connecting to the same type and / or different type of access system in an environment where a plurality of access systems are linked, and activates a module corresponding to the access system. An access system specifying module that connects to the access system and provides a service, information of each access system arranged in the wireless network from the CPC server, and frequency allocation information and load level of each access system A CPC specific module to receive, a reconfiguration manager to control the access system specific module to be reconfigured to communicate with one of the access systems, and a service measured in the currently connected and served access system Quality (Qos Observing, when the quality of the observed service falls below predetermined threshold comprises after searching the best access system for the corresponding service, and a control unit for selecting.

  A method according to an embodiment of the present invention is a method for connecting to the same type and / or different types of access systems in an environment in which a plurality of access systems are linked, and information on each access system arranged in a wireless network. Receiving the frequency allocation information and load level of each of the access systems, and measuring the quality of service (QoS) of the access system currently connected and serviced by the provision of wireless service; Searching and selecting an optimal access system using the location information and load information to provide the corresponding service when the measured quality of the service falls below a predetermined threshold; Reconfiguring the radio to communicate with the selected access system No.

  If the present invention is applied, an access system is selected based on multiple attributes that can be recognized by the user, and the service quality (QoS) is compared with the method based on the existing received signal strength by receiving the service. Service that is easy to secure and adaptable to the communication environment is possible.

1 is a diagram illustrating an interlocking structure of a wireless communication access system according to an embodiment of the present invention. It is a function part structure figure of a user apparatus by an embodiment of the present invention. It is a figure regarding the access system selection procedure in a user terminal by embodiment of this invention. FIG. 4 is a diagram related to measurement of received signal strength using a measurement window according to an embodiment of the present invention. FIG. 6 is a diagram illustrating an operation procedure during a downlink handover using multiple attributes and a utility function according to an embodiment of the present invention. FIG. 6 is a diagram illustrating an operation procedure during upward handover using multiple attributes and a utility function according to an embodiment of the present invention.

  The above-described objects, features, and advantages will be described in detail later with reference to the accompanying drawings. Accordingly, a person having ordinary knowledge in the technical field to which the present invention belongs can easily implement the technical idea of the present invention. I will. In the description of the present invention, detailed description will be omitted when it is determined that a specific description of a known technique related to the present invention can blur the gist of the present invention unnecessarily. It should also be noted that the terms described below are only used to help understand the present invention, and that each manufacturer or research group uses different terms from each other despite the same use. I must. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an interlocking structure of a wireless communication access system according to an embodiment of the present invention.

  In FIG. 1, the access system (Access System, hereinafter referred to as “AS”) includes a 3GPP mobile communication base station 106, a 3GPP long-term evolution (LTE) home eNodeB 109, a Wimax base station (Base Station, hereinafter “ BS ”) 110, WiFi access point (Access Point; hereinafter referred to as“ AP ”) 112, and the like. And, with the development of the access system, the base station not only provides a defined service, but also includes a reconfigurable base station 120 that is reconfigured according to the situation and allows other wireless connection services And a CPC base station 122 providing CPC information may be installed.

  Further, not only the base station (BS) or access point (AP) illustrated in FIG. 1 but also the operation of the base station (BS) or access point (AP) of another wireless communication system operates according to the concept of the present invention. It can be applied if possible. Therefore, it is not limited to the example illustrated above.

  A 3GPP mobile communication base station 106, which is a mobile communication system equipment to which mobile terminals are connected in a wireless manner, is connected to a mobile communication carrier network. The 3GPP mobile communication base station 106 can be simply represented by a NodeB 108 and an RNC 107.

  The NodeB 108 is a name that designates a base station in 3GPP, and represents a general base station. The NodeB 108 can reduce the infrastructure construction cost for connecting from a base station to a control station by using a DSL (Digital Subscriber Line) network or the like to connect to a mobile communication network, and in cooperation with the network system, Various additional service functions can be designed. The NodeB 108 can have several cells, and each cell has a carrier for use in its own cell. The NodeB 108 is connected to many user equipments (User Equipment, hereinafter referred to as “UE”) 130 existing in the cell, and secures a frequency used in the cell. A radio network controller (Radio Network Controller, RNC) 109 is connected to an upper level of the NodeB 108, and not only controls the NodeB 108 but also allocates communication resources, a handover, and a radio bearer (RB). The 3GPP mobile communication base station 106 is based on 3G W-CDMA.

  LTE (Long-term Evolution) home eNodeB 109, which means an evolutionary access network and an evolutionary core network within 3GPP, is undergoing standardization work and will communicate in a manner determined by the standardization work. The eNodeB 109 is a form in which the existing NodeB 108 and the RNC 107 are integrated, and all the protocol layers installed in the existing RNC 107 are included in the eNodeB 109.

  The WiMAX BS 110 and the WiFi AP 112 are capable of voice communication like a mobile phone while being able to communicate with the Internet connection data like a wireless LAN.

  Each of the systems described above (reference numerals 106, 109, 110, 112) corresponds to AS. Then, the AS can include a reconfigurable base station 120 that reconfigures the base station to suit the situation due to the development of AS and enables the service, and a CPC base station 122 that provides 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 cell illustrated. As an example, reference numeral 142 is an eNodeB service network providing 3G LTE service, and reference numeral 144 is a WiMAX BS service network.

  The heterogeneous AS handover corresponds to a case where, for example, a handover is performed from the eNodeB (142) service network to the WiMAX BS (144) service network by changing the cell to an AS of a different type from the currently serviced AS. .

  Homogeneous AS handover refers to changing a cell to an AS of a type that is currently serviced, for example, from an eNodeB (142) service network to an eNodeB (146) service network connected to a system having the same protocol. It corresponds to the case that exceeds.

  Having described the AS example, the interlocking structure of the wireless communication AP will now be described in detail.

  In the present invention, a multi-mode terminal performing a CPC Client function is considered based on a CPC server (Server) 102 that provides AS arrangement information and an SDR (Software Define Radio). The multi-mode terminal means the UE 130. The UE 130 is a multi-mode terminal capable of SDR-based reconfiguration, and is capable of universal access. Here, the universal access is a UE 130 that is a multi-mode terminal capable of SDR-based reconfiguration, selects a specific AS that can be used through an AS search, and is associated with the selected specific AS. The communication module is reconfigured and connected to the AS. The UE 130 incorporates hardware that supports modules such as WCDMA, WiMAX, WiFi, and the like, and provides a service in conjunction with a specific AS.

  The CPC server 102 manages frequency allocation information, AS load information, and AS arrangement information that are dynamically changed in conjunction with a spectrum broker 100 and a CRRM 104. The spectrum broker 100 is in charge of a function of dynamically assigning an AS according to a request and policy of a business operator, and transmits the frequency assignment information of the corresponding AS to the CPC server 102. A CRRM (Cognitive Radio Resource Manager) 104 is a functional entity that performs a radio resource management function of a plurality of ASs. In the present invention, the degree of load of each AS is measured, and this load information is sent to the CPC server 102 or AS. Then, control is performed so as to broadcast again to the UE 130. The CPC server 102 periodically broadcasts the frequency allocation information provided from the spectrum broker 100, the load information of each AS provided from the CRRM 104, and the AS arrangement information set by the operator using the CPC. . The UE 130 periodically receives AS arrangement information and frequency allocation information, obtains information on usable AS, and performs AS in consideration of service requirements and various parameters according to the received AS information. select.

  As described above, the CPC server 102 is a server having a database for managing the arrangement information of the wireless communication AS and the frequency allocation information and load information of each AS presented by the operator, and the arrangement information of the wireless communication AS is transmitted to the UE 130. provide. The information provided from the CPC server 102 according to the embodiment of the present invention can be illustrated as shown in Table 1 below as an example, and this information is periodically transmitted to the user UE 130.

  In Table 1, the AS location information is an AS managed by the operator, so that the operator can use the service effective radius, the position of the neighboring cell (Cell), and the AS You can know the type. In addition, when there is an agreement between operators, it is also possible to know AS information serviced by different operators by exchanging AS arrangement information between the operators.

  FIG. 2 is a functional part structure diagram of a user apparatus according to an embodiment of the present invention.

  It should be noted that the UE according to the present invention is configured for universal access and excludes general functions such as functional blocks such as a key input unit, a display unit, and a battery.

  The UE includes a USIM (User Subscription Information Module) 200, a control unit 220, a reconfiguration manager 204, an AS specific module 206, a GPS module 208, a CPC specific module 210, and a memory 212. Can be configured.

  The USIM 200 stores user identification information and AS priority information set in advance by the user. The USIM 200 can also store an execution program depending on the AS type to be serviced.

  The controller 220 not only controls all functional blocks of the UE, but also performs AS search and selection functions for services in an environment where a plurality of ASs are linked. The controller 220 measures the received signal strength of the AS serviced by the UE and the moving speed information of the UE, and periodically transmits the AS arrangement information and the AS frequency allocation information transmitted from the CPC server 102 and the load of each AS. Receive information.

  The AS selection procedure is started when the quality of service (Quality of Service, hereinafter referred to as “QoS”) measured by an already connected AS is deteriorated, and an AS that satisfies the QoS of the service is selected and connected. To proceed. The controller 220 continuously observes the QoS of the service measured in the currently connected and serviced AS. If the observed QoS falls below a specific threshold, the optimal AS for the service is determined. And proceed to select channels. The AS selection procedure of the UE will be described later with reference to FIG.

  The AS identification module 206 is composed of hardware and software that can support all modules such as WCDMA, WiMAX, WiFi, and the like. The AS identification module 206 is connected to the antenna 205, and transmits / receives data and / or signals to / from the specific AS selected via the antenna 205. The AS identification module 206 can activate (Turn On) the module corresponding to the AS selected by the control unit 220, connect to the AS, and receive a service. In addition, the control unit 220 confirms the received signal strength RSS with the data received by the AS identification module 206 and grasps whether the channel state is serviceable.

  The reconfiguration manager 204 downloads a program of the corresponding AS from the USIM 200 or a business server (not shown) to communicate with the specific AS selected by the control unit 220, and a communication module related to the selected specific AS Set up and control. The reconfiguration manager 204 may be included in the control unit 220.

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

  The CPC identification module 210 receives and processes the out-band CPC information for broadcasting the information of the system arranged in the wireless network using the specific frequency channel, and transmits the information to the control unit 220 after receiving and processing the information via the antenna 209. . The AS load information can be received via the CPC specifying module 210 or the AS specifying module 206.

  The memory 212 stores a program and a control program necessary for execution of the UE, and transmits a corresponding program in response to a request from the control unit 220.

  FIG. 3 relates to an access system selection procedure in a user terminal according to an embodiment of the present invention.

  The AS selection procedure is started when the QoS measured in the currently connected AS decreases, and an AS that satisfies the QoS of the service is selected and connected.

  In step 302, the controller 220 continuously monitors the QoS of the service measured in the currently connected and serviced AS. In step 304, if the observed QoS drops below a specific threshold, the controller 220 performs a procedure for selecting an optimal AS and channel for the corresponding service. If the observed QoS is equal to or greater than a specific threshold, the connection of the currently serviced AS is maintained.

  In order to perform the procedure for connecting to the AS, the controller 220 defines a recommended AS set, a candidate AS set, and an effective AS set for each step. use.

  In step 305, the control unit 220 receives AS arrangement information broadcast from the CPC server 102.

  The control unit 220 uses the placement information for the AS included in the candidate AS set, UE measurement information, and AS load information to determine the AS having the highest score using the derived utility function. The procedure to connect to is performed. The utility function will be described later with reference to FIG.

  In step 308, the control unit 220 generates a recommended AS set based on the information received from the CPC server 102. In step 312, an AS that has a good reception signal and is capable of being serviced is selected from the ASs generated by the recommended AS set, and a candidate AS set is generated. In step 314, the candidate AS set generates a valid AS set after considering the UE movement pattern and the radius of the cell served by the AS. In step 316, a valid AS set calculates a score using a utility function derived from the AS channel condition, AS load condition, and the required quality of service (QoS). In step 318, the control unit 220 selects and connects the AS having the highest score among the valid AS sets.

  Table 2 is an example of attributes to be considered in the access system selection method, and a description of each attribute is shown together.

  Table 3 shows a method of determining the current QoS at the UE using the degree of QoS parameter transition.

  The AS selection method according to the present invention activates a list of recommended AS sets extracted by the AS search procedure. Here, the list means an AS (reference numerals 106, 109, 110, 112) that can be used by searching, and may be one or more. The list activation means that a module built in a UE that provides a service corresponding to each AS is turned on. For example, if a WiMAX AS is searched for in the list of recommended AS sets by the search procedure, the UE turns on a module corresponding to WiMAX among the built-in AS identification modules 206. After activating the list, the control unit 220 checks whether the received signal strength RSS received is in a serviceable state. The received signal strength is a basic parameter for determining whether or not service is possible using the corresponding AS, and the received signal for each AS is based on a measurement window as shown in FIG. Measure strength.

  FIG. 4 relates to received signal strength measurement using a measurement window according to an embodiment of the present invention.

Each AS uses a predefined threshold value of serviceable received signal strength, and the average RSS (E (W) _i ) within the measurement window (measurement window) is greater than the corresponding threshold value (RSSI _threshold ). If so, the corresponding access system is added to the candidate AS set.

Further, the size of the window used for measuring the average value of the received signal strength can be variably set, and the utility function 228 (U (RSS) _i ) is used by using the measured received signal strength. Can be derived. Next, a method for deriving a parameter related to the received signal strength is expressed by Equations 6 to 8.

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

  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 AS selection. it can. However, it is impossible to accurately have information on the movement pattern of the UE, and it is difficult to predict the mobility of the UE. Therefore, in this method, a method is proposed in which the residence time of the cell served by the specific AS is applied using the UE speed and the cell radius. That is, when assuming that the UE performs a linear motion and does not stop during the movement, the residence time of the cell can be predicted based on this.

Since the derived CRT prediction value (CRT (v) _i ) is not an accurate value, the prediction value is not used as a utility function for selecting an AS, and a set-up time (Makeup Time) for connecting a new cell is used. ) Is added to the candidate AS set only when the derived residence time (CRT) is greater than the set time (MT).

  The set time means a time required for a signaling procedure, an authentication procedure, and the like for connecting to a specific AS in order for the UE to receive a service. Expression 9 represents a method for deriving the above-described CRT, and Table 5 represents an operation procedure using CRT-related parameters.

  In the present invention, a method for measuring the degree of load on each AS is required in order to present a method for selecting the optimum AS that matches the service. In order to measure the AS load, a plurality of parameters such as the number of currently connected users, bandwidth occupancy, delay, and delay transition can be used.

The present invention considers processing rate, delay, and jitter to measure the degree of AS load. That is, the serviceable processing amount (T (t) _i ) is predicted in consideration of the maximum capacity of the specific AS, the processing amount serviced by the current AS, and the processing amount requested by the UE. It also compares the ratios of the required delay and jitter values taken into account with important factors in real-time traffic and multimedia traffic to the values currently measured by the AS, and can provide delay (D (t) _i ) and jitter ( J (t) _i ) is predicted.

A utility function for AS loading is derived using the above-described parameters, and is used in the AS selection method based on this. The method of predicting the degree of parameter load is as shown in Expression 10 to Expression 13, and a utility function (U (LOAD) _i ) using the predicted degree of load can be expressed as Expression 13.

In a wireless communication system in which a plurality of ASs operate in conjunction with each other, a user connects to the AS using a connection list that meets his / her requirements and receives a service. Therefore, in the present invention, a priority is assigned to the AS set by the user and used as one parameter for AS selection. AS preference information set by the user can be stored in the USIM 200 of the UE, and the corresponding connection priority can be dynamically changed at the time of initial setting or by the user. Expression 14 represents a method of applying the user preference information to the utility function (U (preference) _i ).

  Table 6 shows an operation procedure for selecting an optimum AS among ASs belonging to a useful system set using the parameters and utility functions described above.

  Channel change and handover procedures between different ASs can be broadly divided into downward handover (Downward Handover, hereinafter referred to as “DH”) and upward handover (Upward Handover, hereinafter referred to as “UH”). it can.

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

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

  FIG. 5 illustrates an operation procedure at the time of a downlink handover using multiple attributes and a utility function according to an embodiment of the present invention.

  FIG. 5 relates to a channel change procedure for the UE from an AS having a global network service area to an AS having a local network service area.

  Downward handover (DH) between heterogeneous access systems is initiated when the QoS measured at the AS to which the UE is currently connected decreases.

  In step 501, the UE is currently registered in the AS having the entire regional service area. In step 503, the control unit 220 operates a measurement timer (not shown). If the QoS of the service falls below a specific threshold, the controller 220 proceeds to step 509 to select the optimal AS and channel for the service.

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

  In step 509, the control unit 220 receives the AS arrangement information periodically broadcast from the CPC server 102, generates a recommended AS set, and can receive a service with a good reception signal among the AS generated by the recommended AS set. Select an AS.

  In step 513, the AS identification module 206 built in the UE activates (Turn On) the module corresponding to the usable AS selected in step 509. For example, if the recommended AS set selects the eNodeB 109 and the BS 110 in step 509, the control unit 220 activates the modules corresponding to the eNodeB 109 and the BS 110 in the AS identification module 206. When the specific module is activated, the process proceeds to step 515, and the control unit 220 evaluates the received signal strength RSS received by the specific module. In step 517, the control unit 220 evaluates the received signal strength and confirms whether the received signal strength is greater than or equal to a predetermined threshold value. That is, it is confirmed whether the slope of the received signal strength is greater than 0 and greater than the specific threshold. If the received signal strength is equal to or greater than a predetermined threshold value, the process proceeds to step 519, and the control unit 220 adds the currently connected AS to the candidate AS set.

  In step 521, the control unit 220 confirms the state of the candidate AS set. The controller 220 checks whether there is a candidate AS set that can be used in consideration of the UE movement pattern and the radius of the cell served by the AS. If there is no candidate AS that can be used in step 521, the process returns to step 501 and proceeds again in the order.

  If there is a usable candidate AS, the process proceeds to step 523, and the control unit 220 checks 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 again in the order.

  If there is a usable candidate AS, the process proceeds to step 525, and the control unit 220 estimates the time (CRT) that the UE stays in the cell. Since the UE has mobility according to the movement pattern, the cell residence time (CRT) can be predicted in consideration of the current speed of the UE and the size of the cell when performing AS selection.

  In step 529, the set time (Makeup Time) for connecting a new cell is compared with the derived residence time (CRT) of the cell. When the time (CRT) in which the UE cell stays is larger than the generation time (MT), the process proceeds to step 531 and the AS to which the UE currently belongs is added to a valid AS set.

  If the UE cell retention time (CRT) is smaller than the connection setup time (MT), the process proceeds to step 527, and the specific module corresponding to the current candidate AS set is turned off (Turn-Off). Then, returning to step 523, the control unit 220 checks whether another candidate AS set exists, and if it exists, resumes in the order described above. If there is no candidate AS set, the process returns to step 501 and restarts from the beginning.

  After adding a valid AS set in step 531, the control unit 220 proceeds to step 540 and checks whether there is a valid AS that can be used. If there is no valid AS, the control unit 220 returns to step 501 and resumes in order from the first step.

  If there is a valid AS in step 540, the process proceeds to step 542, where the control unit 220 uses a utility function derived from the received signal strength, the load information of the access system, and the AS preference set by the user in advance. To calculate the score.

  In step 544, the control unit 220 selects the AS having the highest score, and the AS identification module 206 activates (Turn On) the module corresponding to the selected usable AS, and selects the selected AS. Connecting. After connecting to the selected AS, the control unit 220 registers in the AS in step 546, and then performs a downward handover.

  FIG. 6 illustrates an operation procedure during upward handover using multiple attributes and utility functions according to an embodiment of the present invention.

  FIG. 6 relates to a channel change procedure in which the UE changes from an AS having a regional network service area to an AS having a global network service area.

  Downward handover (DH) between heterogeneous ASs is initiated when the QoS measured in the AS to which the UE is currently connected decreases.

  In step 601, the UE is currently registered in the AS having the regional network service area. In step 603, the control unit 220 operates a measurement timer (not shown).

  In step 605, the control unit 220 continuously observes the QoS state in which the UE is currently served, and checks whether the QoS of the observed service falls below a specific threshold. Then, when the QoS is equal to or higher than the specific threshold value, the handover is not performed and the current AS service is maintained.

  If the QoS of the service falls below a specific threshold, the control unit 220 proceeds to step 607. In step 607, the control unit 220 receives AS arrangement information periodically broadcast from the CPC server 102, generates a recommended AS set, and can provide a service with a good reception signal among the access systems generated by the recommended AS set. Select an AS.

  In step 609, the control unit 220 confirms whether the same type of AS exists among the searched ASs. If there is an AS of the same type, the process proceeds to step 611 and an AS of the same type is selected. That is, if the currently registered AS belongs to the WLAN area, the handover is performed to the same kind of WLAN area in the searched AS. If the same type AS is selected, the control unit 220 proceeds to step 613 and performs the same type of handover connection procedure.

  If the same type AS does not exist in step 609, the process proceeds to step 615, and the specific module corresponding to the different type AS searched by the control unit 220 is activated (turned on). When the specific module is activated, in step 617, the control unit 220 evaluates the received signal strength RSS received from the AS associated with the specific module. In step 619, the control unit 220 confirms the received signal strength and confirms whether it is equal to or greater than a predetermined threshold value. That is, it is confirmed whether the slope of the received signal strength currently received is greater than 0 and greater than a specific threshold.

  If the received signal strength is less than or equal to a predetermined threshold value in step 619, the control unit 220 returns to step 615, and the received signal is good among other ASs generated by the recommended AS set. Activating a specific module corresponding to an AS capable of receiving and evaluating the received signal strength anew. If the received signal strength is equal to or greater than the specific threshold, the control unit 220 proceeds to step 621 and adds the candidate AS set.

  In step 623, the control unit 220 confirms the candidate AS state. The controller 220 checks whether there is a candidate AS that can be used in consideration of the UE movement pattern and the radius of the cell served by the AS. If there is a candidate AS that can be used in step 623, the process proceeds to step 631, and the control unit 220 checks whether the number of AS sets is greater than zero. If there is a candidate AS, the process proceeds to step 633 to estimate the time (CRT) that the UE stays in the cell. Since the UE has mobility according to the movement pattern, the cell residence time (CRT) can be predicted in consideration of the current speed of the UE and the size of the cell when performing AS selection. In step 637, the set time (MT) for connecting a new cell is compared with the derived residence time (CRT) of the cell. If the time (CRT) staying in the UE cell is smaller than the set time (MT), the controller 220 removes the candidate AS set that can be used in step 639 and restarts from step 635. Further, when the time (CRT) staying in the cell of the UE is larger than the generation time (MT), the process proceeds to step 641, and is added to a valid AS set.

  If a valid AS set is added in step 641, the control unit 220 proceeds to step 643 and checks whether there is a valid AS that can be used. If there is no valid AS in step 643, the control unit 220 proceeds to step 625 and checks AS preference information set in advance by the user. In step 627, the control unit 220 activates (turns on) a specific module corresponding to the entire area network, and proceeds to step 629 to perform a connection procedure.

  If no candidate AS is available in step 623, the process proceeds to step 625, and steps 627 and 629 are performed in the same manner as described above.

  If there is a valid AS in step 643, the process proceeds to step 645, where the control unit 220 uses the utility function derived from the received signal strength, AS load information, and preference information preset by the user (score ( (Score) is calculated. In step 647, the control unit 220 selects the AS having the highest score, and the AS identification module 206 activates (Turn On) the module corresponding to the selected usable AS and connects to the selected AS. To proceed. The controller 220 performs a procedure for connecting to the selected AS, and then performs an upward handover by registering with the AS in step 649.

100 Spectrum Broker 102 CPC Server 104 CRRM (Cognitive Radio Resource Manager)
106 3GPP mobile communication base station 107 RNC
108 NodeB
109 eNodeB
110 Base station (BS)
112 Access point (AP)
120 reconfigurable base station 122 CPC base station 130 UE
200 USIM (User Subscription Information Module)
204 Reconfiguration Manager 206 AS Identification Module 208 GPS Module 210 CPC Identification Module 212 Memory 220 Control Unit

Claims (10)

In a user equipment (UE) for connecting to a homogeneous and / or heterogeneous access system in an environment where multiple access systems work together,
An access system identification module that activates a module corresponding to the access system and connects to the access system to provide a service;
A CPC specifying module for receiving information of each access system arranged in the wireless network from the CPC server, frequency allocation information of each of the access systems, and the degree of load;
A reconfiguration manager that controls the access system specific module to be reconfigured to communicate with one of the access systems;
When the service quality (QoS) measured by the currently connected and serviced access system is observed and the observed service quality falls below a predetermined threshold, the optimum access system for the corresponding service An access system selection device comprising: a control unit that selects after searching. The CPC specific module is
The access system selection apparatus according to claim 1, wherein information on each access system arranged in the wireless network is received using out-band CPC (Out band CPC) information using a specific frequency channel. The reconfiguration manager
The access system selection device according to claim 1, wherein the access system program is downloaded from a provider server, and the access system identification module associated with the selected specific access system is reconfigured.   The access system selection device according to claim 1, further comprising a USIM that stores user identification information and priority information of the access system preset by the user.   The access system selection device according to claim 1, further comprising a GPS module that provides location-based services and location information.   2. The access system selection device according to claim 1, further comprising a memory in which a program necessary for execution of the user device and a control program are stored. The optimal access system search in the control unit,
Generating a usable recommended access system set based on the information received from the CPC server;
From the generated recommended access system set, select a candidate access system set that can be serviced with a good received signal,
The selected candidate access system set takes into account the current speed of the user equipment and the size of the cell, and predicts the residence time of the cell. The generation time for connection of a new cell and the predicted residence of the cell The access system selection device according to claim 1, wherein when the time is larger than the generation time, an optimum access system is searched by generating an effective system set. The effective access system set generation is
The access according to claim 7, further comprising a utility function derived from a channel state, an access system load state, and a service request necessary for selecting an optimal access system in the selected candidate access system set. System selection device. In a method for connecting to homogeneous and / or heterogeneous access systems in an environment where multiple access systems work together,
Receiving information of each access system arranged in a wireless network, frequency allocation information of each access system and a degree of load;
Measuring quality of service (QoS) of an access system provided with wireless service and currently connected and serviced;
When the measured quality of the service falls below a predetermined threshold, searching for and selecting an optimal access system using the location information and load information to provide the service;
Reconfiguring a radio unit to communicate with the selected access system. The optimal access system search is
Generating a usable recommended access system set based on information received from the CPC server;
Selecting a candidate access system set in which the received signal is good and can be serviced among the generated recommended access systems;
In the selected candidate access system set, the residence time of the cell is predicted in consideration of the current speed of the user equipment and the cell size, the generation time for connection of a new cell and the predicted residence time of the cell The access system selection method according to claim 9, further comprising: generating an effective system set if is greater than the generation time.

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