Method of controlling cell selection for a wireless communication system and related device

Method for controlling cell selection in wireless communication system and related device

The present invention refers to a method and device used in a wireless communication system, in particular to a method and related device used in a wireless communication system to control cell selection.

The System Architecture Evolution (SAE) system, which is regulated by the Third Generation Mobile Telecommunications Alliance (3GPP), is a new core network architecture in the Universal Mobile Telecommunications System (UMTS), which is the Internet The mass market of Internet Protocol (IP) provides cost-effective deployment and operation. Network evolution mainly includes meeting the wireless interface requirements of a long-term evolution (LTE) system, simplifying the network structure, and all-IP network (that is, all services are transmitted by packet switching, excluding circuit switching technology), and Supports continuity of actions and services between different types of access networks, such as 2G/3G, long-term evolution systems, and non-3GPP access systems.

System architecture evolution The system includes a Mobility Management Entity (MME), a Serving Gateway (Serving Gateway), and a Public Data Network Channel (PDN Gateway). The mobile management system is a control plane entity used to manage network service additions, client authentication, and coordinate the establishment of related wireless loads in the evolutionary wireless access network.

The function of the system architecture evolution system includes the non-access-stratum (NAS) function performed by the client in the idle mode, and an evolved universal mobile communication system is used between the client and the evolved packet core network (Evolved UMTS, E-UTRAN) the non-access layer signaling process, and the third layer signaling process between the user terminal and the evolved packet core network through the non-3GPP access network. Among them, the evolved universal mobile communication system includes a plurality of evolved base stations.

In the non-access layer, local cell deployment is defined as the use of a single base station in a building or a small cell group, such as in a campus. Access to local cells is limited to specific subscribers. In the deployment of local cells, a Closed Subscriber Group (CSG) cell is a part of the public land mobile network (PLMN). When the cell identification of the Closed Subscriber Group cell is stored in a client When there is a whitelist, the client can access the closed user group cell. The service scope of a closed user group cell can be a home, a building, or a campus. The whitelist provides cell identification for multiple closed user group cells that can be accessed, which means that the client is allowed to reside in the service range of the closed user group cells provided by the whitelist.

An attach process and a Tracking Area Updating (TAU) process are both Evolved Packet System Mobility Management (EMM) processes in the non-access layer signaling process, and can be used for updating The white list on the client side. In addition, local cell deployment provides two ways to use the whitelist, which are shown in the following methods (A) and (B).

In method (A), a closed user group area is defined as a tracking area, which contains a cell or a cell group, and only users with access rights can access the closed user group cells. An individual cell can belong to a tracking area (TA) or a closed user group tracking area (CSG-TA). In order to achieve "multiple tracking area registration", the mobile management entity allocates multiple tracking areas and closed user group tracking areas to the client. As part of the additional process or tracking area update process, the action management entity can provide one or more tracking area cells (TACs) on the client side to identify a closed user group or non-closed user group tracking area. If the tracking area can identify a closed user group, the client adds the closed user group to the whitelist. The mobile management entity instructs the user terminal whether a subscribed closed user group belongs to the current registered area of the user terminal. If so, the user terminal does not start the tracking area update process when entering the closed user group.

In addition, the mobile management entity checks whether the closed user group tracking area identification is subscribed by the client. If the closed user group tracking area identification is not subscribed by the client, the mobile management entity denies the client access to the network.

In method (B), a closed user group area contains one or a group of cells, and its access is restricted to a group of users. An individual cell can belong to a closed user group area or a non-closed user group area. In order to achieve "multiple tracking area registration", the mobile management entity allocates multiple tracking areas to the client. A closed user group cell area identification includes a tracking area authentication and a cell identification code. The whitelist used to provide cell area authentication for the closed user group can be stored in the Universal Integrated Circuit Card (UICC). The mobile management entity provides the whitelist in the same way as the public mobile network or the tracking area list (such as the receiving message of the additional/tracking area update process). The client's whitelist remains valid until the client receives a new whitelist from the next authorization management message process, or deletes all whitelist details according to network instructions. The user end should regard all closed user group cells that are not part of the closed user group of the user end as an inappropriate cell.

In addition, regardless of whether the mobile management entity is authorized or not, a base station belonging to the closed user group area transmits the closed user group cell area identification to the mobile management entity, such as tracking area identification plus cell identification. Upon receiving a new reason value, the client removes the closed user group cell area identification (that is, expired information) from the stored whitelist. This method prevents the client from accessing unallowed cells.

In method (A), the white list includes multiple closed user group tracking areas, and in method (B), the white list includes cell identification with tracking areas and cell identities.

In the conventional technology, there are two problems in the cell selection on the user side. The first problem is in the method (A) or (B). The white list is updated through an additional process or a tracking area update process. However, the additional process and the tracking area update process can only be initiated by the client. The start trigger condition of the additional process is that the user terminal wants to enter an evolved packet system mobility management connection mode from an evolved packet system mobility management idle mode. In addition, in the prior art, the tracking area update process is a conditional or periodic update of the tracking area, or when the user terminal changes across systems.

It can be seen from the above that the user terminal can only start the additional process or the tracking area update process when it meets certain conditions, which means that the user terminal cannot start the additional process or the tracking area update process at any time. In addition, when the client performs the additional process or the tracking area update process, the network can only update the whitelist of the client.

Because the client must wait until the whitelist update is completed, that is, add closed user group cells to the whitelist through the additional or tracking area update process, the client cannot immediately access a newly subscribed closed user group cell. Even if the user terminal finds a newly subscribed closed user group cell as the best cell when reselecting the cell, the user terminal still cannot select this closed user group cell because this cell is not in the whitelist.

In the second question, according to the conventional technology, the cell measurement and reselection rules for macro cells can also be applied to the closed user group cells. In addition, users who subscribe to a closed user group cell to receive services will save communication costs more than through a non-closed user group cell. When the client is in the service range of a large cell and a closed user group cell that has been subscribed at the same time, and accepts the service of the large cell, the client can perform cell reselection only when the conditions for cell selection are established , To select the closed user group cell, or even the user terminal does not measure the closed user group cell because the closed user group cell is not qualified for measurement. In this case, the client can only continue to receive services through the large cell, even if the user has entered the service range of the closed user group cell.

In the above-mentioned conventional technology problem, when an appropriate closed user group cell is found or subscribed, the user terminal cannot immediately select or access the closed user group cell, and the communication quality cannot be optimized.

In addition, in addition to the above problems, the whitelist of the client may include a group of closed user group cells that have not been subscribed by the client. The existing relevant technical specifications have not formulated a method for processing the whitelist in this case. In addition, when the client resides in a closed user group cell that has not been subscribed but appears on the whitelist, the existing relevant technical specifications do not specify how the client or the network should deal with this situation, resulting in closed users Circumstances in which the group cell is misused by the unsubscribed client.

The main purpose of the present invention is to provide a method for controlling cell selection in a closed user group in a wireless communication system and related devices to solve the above-mentioned problems.

The present invention discloses a method for controlling cell selection in a closed user group, which is used in a wireless communication system including a network terminal and a client terminal, and the client terminal includes a closed user group cell that can provide multiple access White list, the method includes: updating the white list when the client subscribes to a closed user group cell that does not belong to the white list or does not subscribe to a closed user group cell of the white list.

The present invention further discloses a method for controlling cell selection of a closed user group in a user terminal of a wireless communication system. The user terminal includes a white list that provides a plurality of closed user group cells that can be accessed. The method It includes: when the client resides in a large cell and the condition for starting the closed user group cell measurement is not established, periodically searching for closed user group cells belonging to the whitelist according to a search cycle.

The present invention also discloses a method for controlling cell selection in a closed user group in a user terminal of a wireless communication system, the user terminal including a whitelist that can provide a plurality of closed user group cells that can be accessed, The method includes: when a closed user group cell is added to the white list, a closed user group cell search is performed.

The present invention also discloses a method for controlling cell selection of a closed user group in a user terminal of a wireless communication system. The user terminal includes a white list that can provide a plurality of closed user group cells that can be accessed. The method includes: when a closed user group cell currently resident on the client terminal is removed from the white list, cell selection is performed to select a cell for the client terminal to reside in.

The present invention also discloses a method for controlling cell selection in a closed user group, which is used in a user terminal of a wireless communication system including a network terminal, and the client terminal includes a closed user that can provide a plurality of accessible users The method includes: when the client resides in a closed user group cell belonging to the white list, and the client has not subscribed to the closed user group cell, receiving a message from the network Paging message; when receiving the paging message, start a service request process; through the service request process, receive a service rejection message, where the service rejection message includes a rejection reason value indicated by the network; and when receiving the service request process For the rejection reason value of the service rejection message, search for a cell outside the closed user group cell.

Please refer to Figure 1, which is a schematic diagram of a wireless communication system 10. The wireless communication system 10 includes a System Architecture Evolution Core Network (SAE CN) 102, a large cell 104, an evolved universal mobile communication system access network 105, and a user terminal 106. Among them, the large cell 104 includes a plurality of closed subscriber group (CSG) cells 108 and 110. For simplification, only one user terminal 106 is drawn in Figure 1. For the client 106 that has subscribed to multiple closed user group services, the area located in the service range of the large cell 104 and outside the service range of the closed user group cell 108 and 110 is regarded as the service range of the non-closed user group cell . The range of the closed user group cells 108 and 110 is smaller than the range of the large cell 104, and can be the size of a home, a building, or a campus. System architecture evolution The system core network 102 includes a mobility management entity (Mobility Management Entity) 112, which is a control plane entity that performs non-access layer communication through a wireless interface between the user end 106 and the Evolved Universal Mobile Communication System access network 105, among which the Evolved Universal Mobile Communication System access The network 105 includes at least one base station. For the purpose of the closed user group cell selection in the non-access layer, the client 106 stores a white list that can provide a plurality of closed user group cells that can be accessed. In other words, according to the settings of the mobile management entity 112, the whitelist may include a plurality of closed user group cells, or may not include any closed user group cells.

In addition, the client can initiate an additional process and a tracking area update process to update the whitelist. The wireless communication system 10 provides several measurement conditions. When any measurement condition on the user side is established, a more suitable service cell can be reselected.

Please refer to FIG. 2, which is a schematic diagram of a wireless communication device 20 according to an embodiment of the present invention. The wireless communication device 20 can be the client 106 or the mobile management entity 112 in FIG. 1, and it includes a processor 200, a computer-readable recording medium 210, a communication interface unit 220, and a control unit 230. The computer-readable recording medium 210 can be any data storage device for storing a stored data 212, which includes a program code and non-access layer parameters, and is read and processed by the processor 200. The computer readable recording medium 210 may be read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tape ( magnetic tapes, floppy disks, optical data storage devices) or carrier signal (such as Internet data transmission). When the communication device 20 is used on the client side, the non-access layer parameters include a white list. The control unit 230 is used for controlling the state and related operations of the communication interface unit 220 and the communication device 20 according to the processing result of the processor 200. The communication interface unit 220 is used to exchange wireless signals with other wireless communication devices. For different purposes, the communication interface unit 220 can be implemented through different interface devices. When the communication device 20 is the client 106, the communication interface unit 220 is a wireless receiver for wireless communication with the base station. When the communication device 20 is the mobile management entity 112, the communication interface unit 220 is an Ethernet device for exchanging non-access layer signals with the client through the base station.

Please refer to FIG. 3, which is a flowchart of a process 30 according to an embodiment of the present invention. The process 30 is applied to the non-access layer function between the client (such as the client 106) and the network (such as the mobile management entity 112) to control the cell selection of the closed user group, and can be compiled and stored in the computer. Read the program code of the stored data 212 in the recording medium 210. Process 30 includes the following steps:

Step 300: Start.

Step 302: When a client subscribes to a closed user group cell that does not belong to a whitelist of the client, a mobile management entity sends a Detach message with a re-attach request.

Step 304: The client initiates an additional process.

Step 306: Through the attachment process, the mobile management entity sends an ATTACH ACCEPT message including a newest whitelist to the client.

Step 308: The client replaces the white list with the latest white list.

Step 310: End.

According to the process 30, when the client subscribes to the closed user group cell that is not in the whitelist, the embodiment of the present invention controls the mobile management entity to send a detach message with a re-attach request to the client. Then, the client initiates the additional process by sending an additional request message to the mobile management entity. In response to the additional request message, the mobile management entity generates the latest whitelist, which includes the original closed user group of the client and the closed user group that is not part of the original whitelist but has been subscribed. The additional acceptance message including the latest whitelist is then sent to the client. Finally, the client uses the latest whitelist to replace the original whitelist. In this way, the client can immediately access the closed user group cells that are not part of the whitelist of the client.

When the client subscribes to a closed user group cell that does not belong to the whitelist, the client can update the whitelist through the process 30 to ensure that the client can access the rights of such closed user group cells.

For example, the client 106 residing in the large cell 104 subscribes to the closed user group cell 108, but when the closed user group cell 110 that is not in the whitelist of the client 106 is more suitable for serving the client 106, according to the conventional technology, When the client 106 subscribes to the closed user group cell 110, the client 106 cannot access the closed user group cell 110. It must wait until the client 106 starts the additional process or the tracking area update process and obtains the access permission before accessing the closed user Group cells 110, this may cause serious delays. According to the process 30 of the present invention, when the client 106 subscribes to the closed user group cell 110, it immediately requests to start the additional process or the tracking area update process, and the mobile management entity (ie, the network) actively updates the client 106 whitelist. Therefore, the client in the embodiment of the present invention can alleviate the phenomenon of delayed access to the cells of the closed user group.

It is worth noting that those who are familiar with the field can determine the content of the latest whitelist and how the user terminal adds closed user group cells that are not part of the original whitelist. Taking the purpose of saving wireless resources as an example, the mobile management entity can generate the latest whitelist, which only includes closed user group cells that are not part of the original whitelist. The user terminal directly adds the closed user group cells in the latest whitelist to the original whitelist. In this way, compared with the process 30, this method can reduce the amount of data transmission required in the process of updating the whitelist, thereby saving more wireless resources.

Please refer to FIG. 4, which is a schematic diagram of a process 40 according to an embodiment of the present invention. The process 40 is applied to the non-access layer function between the client (such as the client 106) and the network (such as the mobile management entity 112) to control the cell selection of the closed user group, and can be compiled into storage data 212 The code. The process 40 includes the following steps:

Step 400: Start.

Step 402: When the user terminal subscribes to a closed user group cell that is not in the white list, the mobile management entity sends a message to the user terminal to add the closed user group cell that is not in the white list to the white list.

Step 404: End.

According to the process 40, when the client subscribes to a closed user group cell that does not belong to the whitelist of the client, the mobile management entity of the embodiment of the present invention directly sends a message to the client to add a closed user group that does not belong to the whitelist Cells to the white list.

Preferably, when the user terminal communicates with the evolved universal mobile communication system, the message is a non-access layer function message of the long-term evolution wireless system. According to various processes, the message can be a short message service (SMS), a connection management service rejection (CM SERVICE REJECT) message, a service rejection (SERVICE REJECT) message, and an additional rejection (ATTACH REJECT) message. ) Message, a TRACKING AREA UPDATE REJECT message, a ROUTING AREA UPDATE REJECT message, or a LOCATION UPDATING REJECT message. Among them, if the user terminal is operating in the Global System for Mobile Communications/Enhanced Data Rate GSM Evolution Radio Access Network (GSM EDGE Radio Access Network, GERAN) or Universal Mobile Radio Access Network (UMTS radio access network, UTRAN), the The message is realized using a short message service message.

The process 30 updates the white list by attaching or tracking the area update process, and the mobile management system of the process 40 updates the white list by directly sending a message. Compared with the process 30, the process 40 does not need to interrupt the service, so that the user terminal can continue to receive the service when subscribing to a closed user group cell that is not in the whitelist. Therefore, the process 40 can save more signaling resources.

Please refer to FIG. 5, which is a schematic diagram of a process 50 according to an embodiment of the present invention. The process 50 is applied between the client terminal (such as the client terminal 106) to control the cell selection of the closed user group, and can be compiled into a code that stores the data 212. The process 50 includes the following steps:

Step 500: Start.

Step 502: When subscribing to a closed user group cell that does not belong to the white list, manually add the closed user group cell to the white list.

Step 504: End.

According to the process 50, when the user terminal in the embodiment of the present invention subscribes to a closed user group cell that does not belong to the white list, the user terminal updates the white list by itself, instead of relying on the action management entity of the processes 30 and 40 to update the white list. Among them, the user terminal manually adds the cells of the closed user group to the white list to increase the speed of accessing the cells of the closed user group.

Please refer to FIG. 6, which is a schematic diagram of a process 60 according to an embodiment of the present invention. The process 60 is applied between the client terminal (such as the client terminal 106) to control the cell selection of the closed user group, and can be compiled into a code that stores the data 212. The process 60 includes the following steps:

Step 600: Start.

Step 602: When the client resides in a large cell and the condition for starting the closed user group cell measurement is not established, periodically search for closed user group cells belonging to the whitelist according to a search cycle.

Step 604: End.

According to the process 60, when the client resides in a non-closed user group cell (such as the large cell 104) and the condition for starting the closed user group cell measurement is not established, the client periodically searches for the closed user group cell belonging to the whitelist.

Preferably, the search period is assigned by a network signaling message to remove all closed user group cells in the whitelist. The network signaling message can be an additional acceptance message as one of the additional procedures or a TRACKING AREA UPDATE ACCEPT message as one of the tracking area update procedures. The parameters of the search period are stored in a Subscriber Identity Module (SIM) on the client side or, if the subscriber identity module does not support storing the search period, the parameters of the search period are stored in a flash memory. When the user terminal resides in the Global System for Mobile Communications/Enhanced Data Rate GSM Evolution Wireless Access Network or Global Mobile Communications Improvement or Universal Mobile Wireless Access Network, and the variable of the search cycle is stored in the user identification module, the search cycle It is assigned by the short message service message. From the perspective of power consumption, the search period can be set to several minutes, preferably 5 minutes. In addition, the periodic cell search can operate in the background, so it does not affect the operation of other services, such as terminal paging.

Through the process 60, the client can select a subscribed closed user group cell with less time delay. For example, when the client 106 resides in a large cell 104, according to the prior art, only when any measurement condition that the client 106 can trigger cell reselection is established, the client 106 can reselect the closed user group cell 108 becomes an opportunity for a service cell. According to the process 60, when the measurement conditions of the client 106 are not established, the client 106 starts to periodically search for the closed user group cell in the white list to reselect the closed user group cell 108 as a service cell. Based on the above, the service fee for accessing a closed user group cell that has been subscribed will be less than the service fee for accessing a non-closed user group cell. In addition, since the closed user group cells that have been subscribed will limit the number of subscribed clients, better communication quality can be provided. Based on the above points, through the process 60, the user end can obtain better communication quality with less service cost.

Please refer to Figure 7, which is a schematic diagram of a process 70 according to an embodiment of the present invention. The process 70 is applied to the client (such as the client 106) to control the cell selection of the closed user group, and can be compiled into a program code for storing the data 212. The process 70 includes the following steps:

Step 700: Start.

Step 702: When a closed user group cell is added to the white list, perform a closed user group cell search.

Step 704: End.

According to the process 70, when a new closed user group cell is added to the white list, the client starts to search for the closed user group cell belonging to the white list. In this case, even if the measurement condition of the closed user group cell is not established, the user terminal can still select a closed user group cell again. In addition, when a closed user group cell search is completed and no new closed user group cell can be found, the user terminal stops the closed user group cell search.

On the other hand, the client may not subscribe to all closed user group cells in the whitelist. In this case, the following provides a plurality of procedures to prevent the user from accessing unsubscribed closed user group cells by mistake. Please refer to Figure 8, which is a schematic diagram of a process 80 according to an embodiment of the present invention. The process 80 is applied to the network to control the cell selection of the closed user group, and can be compiled into a code that stores the data 212. The process 80 includes the following steps:

Step 800: Start.

Step 802: When the client does not subscribe to the closed user group cells belonging to the white list, the white list is updated by removing the closed user group cells belonging to the white list.

Step 804: End.

According to the process 80, when the client does not subscribe to the closed user group cells belonging to the whitelist, the network side updates the whitelist by removing the closed user group cells. Therefore, according to the updated white list, the client will not search for closed user group cells that have not been subscribed during the next cell search.

In order to remove the closed user group cell, preferably, when the client does not subscribe to the closed user group cell belonging to the whitelist, the network first sends a separation message with a re-attach request to the client. Then, the client initiates an attach process to respond to the re-attach request. Through the additional process, the network sends an additional acceptance message to the client, where the additional acceptance message includes an up-to-date whitelist, which does not include closed user group cells that have not been subscribed in the original whitelist. Finally, the user terminal removes the closed user group cells according to the latest whitelist.

In addition, another preferred way to remove the closed user group cells is described below. The network directly sends a message to the client, and the client removes the closed user group cell based on this message. Preferably, the message is used in the non-access layer function of a system architecture evolution system of a global mobile communication system/enhanced data rate GSM evolution wireless access network, a general mobile communication system or a long-term evolution communication system. The type of SMS can be a short message service message, a connection management service rejection message, a service rejection message, an additional rejection message, a tracking area update rejection message, a routing area update rejection message or a location update rejection message.

Except for the process 80, when the user terminal has not subscribed to the closed user group cells belonging to the white list, the closed user group cells in the white list can be manually removed.

When the closed user group cells that have not been subscribed are removed from the white list, the embodiment of the present invention further provides the following procedures on the user side to subsequently process the white list. Please refer to Figure 9, which is a schematic diagram of a process 90 according to an embodiment of the present invention. The process 90 is used in a client to control the cell selection of the closed user group and can be compiled into a program code for storing the data 212. The process 90 includes the following steps:

Step 900: Start.

Step 902: When a closed user group cell currently resident on the user terminal is removed from the white list, cell selection is performed to select a cell for the user terminal to reside.

Step 904: End.

According to the process 90, when the closed user group cell currently resident on the user terminal is removed from the white list, the user terminal performs cell selection to select a new cell to reside. The selected cell is not a closed user group cell currently resident, but can be a closed user group or a normal cell. Through the process 90, when the closed user group cell currently hosted by the client is removed from the whitelist, the client actively selects a new cell to reside.

Please refer to FIG. 10, which is a schematic diagram of a process 1000 according to an embodiment of the present invention. The process 1000 is applied to a client and a network to control the cell selection of the closed user group, and can be compiled into a code for storing data 212. The process 1000 includes the following steps:

Step 1002: Start.

Step 1004: When a client resides in a closed user group cell belonging to a whitelist, but has not subscribed to the closed user group cell, a network end sends a paging message to the client.

Step 1006: When receiving the paging message, the client initiates a service request process.

Step 1008: Through the service request process, the network sends a service rejection message to the client, where the service rejection message includes a rejection reason value.

Step 1010: When receiving the rejection reason value of the service rejection message, the client searches for a cell other than the closed user group cell.

Step 1012: End.

According to the process 1000, when the client has not subscribed to the current closed user group cell, the network sends a paging message. When receiving the paging message, the client initiates the service request process. Among them, the network terminal sends a service rejection message with a rejection reason value to the client terminal to start the client terminal to search for cells other than the currently resident closed user group cell. Therefore, through the process 1000, when the client has not subscribed to the closed user group cell that currently resides, the network actively requests the client to search for other cells to reside.

Preferably, the searched cell can be a closed user group cell or a general cell. The preferable value of the rejection reason value is 15. The closed user group cells currently residing on the client terminal and the searched cells can belong to the same or different public mobile networks, which are defined as different areas. The defined area can be a routing area, a tracking area, or a location area. In this case, when the cell is searched and found in other routing areas, tracking areas, or location areas, the client correspondingly initiates a routing update process, a tracking update process, or a location update process. Through the routing, tracking, or location update process initiated by the client, the network sends a routing area update acceptance message, a tracking area update acceptance message, or a location update acceptance message to the client, respectively. Wherein, any of the above-mentioned update acceptance messages includes an up-to-date white list, which does not include closed user group cells that have been resident in the original white list but have not been subscribed. Therefore, the user terminal removes the currently resident closed user group cells from the original white list according to the latest white list.

In another case, when the searched cell is used as the current resident cell (where the cell belongs to a mobile network located in a different or the same public land, a global system for mobile communications/enhanced data rate GSM evolution wireless access Take the network or other location areas of the universal mobile communication system), the user terminal initiates the location area update process or the routing area update process instead of initiating one of the aforementioned three area update processes. In this case, the network terminal sends a location area update acceptance or routing area update acceptance message according to the initial process to trigger the client to remove the currently resident closed user group cell from the whitelist.

Therefore, when the closed user group cell currently resident on the client belongs to the whitelist and has not been subscribed, the process 1000 may enable the client to move to another cell and remove the closed user group cell currently residing in the whitelist.

Process 30-50 solves the first problem of conventional technology by quickly updating the white list. Processes 60-70 solve the second problem of the conventional technology by periodically searching for cells and updating the white list. Processes 80-90 and process 1000 deal with the situation when the client resides in an unsubscribed closed user group cell, and the closed user group cell currently resides in the client is deleted from the white list.

In summary, the embodiments of the present invention improve the closed user group cell selection on the user side and avoid system errors.

The foregoing descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.

<p>10. . . Wireless communication system</p><p>102. . . System architecture evolution system core network</p><p>104. . . Large cell</p><p>105. . . Evolved Universal Mobile Communication System Wireless Access Network</p><p>106. . . user terminal</p><p>108, 110. . . Closed user group cell</p><p>112. . . Action management entity</p><p>eNB. . . Base station</p><p>20. . . Communication device</p><p>200. . . processor</p><p>210. . . Computer readable recording media</p><p>212. . . Save data</p><p>220. . . Communication interface unit</p><p>230. . . control unit</p><p>30, 40, 50, 60, 70, 80, 90, 1000. . . process</p><p>300, 302, 304, 306, 308, 310, 400, 402, 404, 500, 502, 504, 600, 602, 604, 700, 702, 704, 800, 802, 804, 900, 902, 904, 1000, 1002, 1004, 1006, 1008, 1010, 1012. . . step</p>

Figure 1 is a schematic diagram of a wireless communication system.

Figure 2 is a schematic diagram of a communication device according to an embodiment of the present invention.

Figures 3-10 are flowcharts of various embodiments of the present invention.