The present invention relates to a base station apparatus, a communication apparatus, a control method, and a computer-readable storage medium, and specifically relates to a connection control technique in a wireless communication system in which different types of wireless communication techniques coexist.
Today, in order to improve the system capacity and throughput in future wireless access networks, a method for using Long-Term Evolution (LTE) and a wireless LAN (WLAN) in coordination with each other has been studied (see NPL 1). With this method, a terminal performs communication by connecting to an access point (AP) on the WLAN side under control of a base station (eNB) on the LTE side (in response to an instruction from the eNB).
NPL 1: Intel et al., RP-150510, “LTE-WLAN Radio Level Integration and Interworking Enhancement,” 3GPP, March 2015.
For example, in the case of Dual Connectivity where an eNB of LTE, together with another eNB of LTE, performs communication with one wireless terminal, the eNB of LTE can precisely acknowledge the state of the wireless terminal because every communication performed by the wireless terminal is completed within an LTE system. When a failure has occurred in communication between another eNB and a wireless terminal, an eNB can continue communication under Dual Connectivity by causing the wireless terminal to connect to still another eNB. On the other hand, regarding communication between a wireless terminal in a wireless LAN and an AP, the eNB cannot acknowledge the status of the wireless terminal in that communication. Therefore, they may be cases where an eNB cannot appropriately execute connection control for a wireless terminal in a wireless LAN.
The present invention provides a technique to enables appropriate execution of connection control in a case where different types of wireless systems are used in parallel.
A base station apparatus according to one aspect of the present invention is a base station apparatus in a wireless communication system that includes the base station apparatus and a terminal capable of connecting to the base station apparatus in a first system and connecting to another apparatus in a second system. The base station apparatus includes: an obtainment unit configured to, when a failure has occurred in connection in the second system between the terminal and the another apparatus, obtain information indicating whether the failure is attributed to suspension of communication functions of the terminal in the second system; and a control unit configured to control connection of the terminal in the second system based on the information.
A communication apparatus according to another aspect of the present invention is a communication apparatus in a wireless communication system that includes a base station apparatus and the communication apparatus, the communication apparatus being capable of connecting to the base station apparatus in a first system and connecting to another apparatus in a second system. The communication apparatus includes a notification unit configured to, when a failure has occurred in connection in the second system between the communication apparatus and the another apparatus, notify the base station apparatus of information indicating whether the failure is attributed to suspension of communication functions of the communication apparatus in the second system. The base station apparatus controls connection of the communication apparatus in the second system based on the information.
The present invention enables appropriate execution of connection control in a case where different types of wireless systems are used in parallel.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings. Note that the same reference numerals denote the same or like components throughout the accompanying drawings.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the present invention, and together with a description thereof, serve to explain the principles of the present invention.
The following describes an embodiment of the present invention in detail with reference to the accompanying drawings.
Furthermore, although it will be assumed below that the wireless terminal that connects to the cellular base station apparatus (the eNB of LTE) further attempts to connect to a wireless LAN AP, no limitation is intended in this regard. That is to say, the following discussion can be applied to a system in which a first communication apparatus in an arbitrary first system that leads communication control connects to a wireless terminal, and the wireless terminal further connects to a second communication apparatus in an arbitrary second system in response to an instruction from the first communication apparatus. It will be assumed that the wireless terminal is capable of, for example, suspending communication functions related to the second system separately from communication functions related to the first system. Furthermore, the wireless terminal can be capable of, for example, suspending the communication functions related to the first system separately from the communication functions related to the second system. For example, similarly to a conventional smartphone, the wireless terminal is capable of suspending cellular communication functions and wireless LAN communication functions separately.
When, for example, another eNB of LTE and one wireless terminal are connected to each other under Dual Connectivity, an eNB can acknowledge the state of communication between another eNB and the wireless terminal because this communication is also related to LTE. Furthermore, as long as connection between an eNB and a wireless terminal is formed, LTE communication functions of the wireless terminal are not suspended. On the other hand, a wireless terminal can suspend the wireless LAN communication functions while communicating with an eNB via LTE. That is to say, in wireless LAN communication, an RLF could possibly occur due to suspension of communication functions by the wireless terminal. In this case, even if the eNB instructs the wireless terminal to connect to another AP, the wireless terminal may not be capable of connecting to another AP because the wireless terminal may have suspended the wireless LAN communication functions.
In view of this, in the present embodiment, when a failure has occurred in wireless LAN connection of the wireless terminal, the eNB obtains information indicating whether the failure is attributed to suspension of the wireless LAN communication functions of the wireless terminal. Here, the eNB can obtain this information from the wireless terminal, for example. In this case, when a failure has occurred in wireless LAN connection, the wireless terminal can notify the eNB of information indicating whether the failure is attributed to suspension of the wireless LAN communication functions of the wireless terminal using, for example, a predetermined message. For example, this predetermined message may be an SCGFailureInformation message for Dual Connectivity defined by 3GPP, or a message in any other format. Furthermore, this information may be transmitted via a control channel, or may be transmitted via a data channel. Note that in a case where a failure has occurred in wireless LAN connection when the wireless LAN communication functions of the wireless terminal have not been suspended, the wireless terminal can transmit information indicating that the failure is not attributed to suspension of the wireless LAN communication functions of the wireless terminal. In this case, the information may include information related to another reason of the occurrence of the failure. For example, when the failure has occurred because a term in which the establishment of wireless LAN connection failed or a term in which communication failed has exceeded a predetermined length, the wireless terminal can notify the eNB of the fact that a term in which communication was unable to be performed has exceeded the predetermined length as a cause of the failure. Note that when the failure has occurred in wireless LAN connection due to another cause, the wireless terminal can similarly notify the eNB of that cause.
The wireless terminal can notify the eNB of information (e.g., BSSID) that designates an AP that served as a connection target until then. This enables the eNB to acknowledge the location of the occurrence of the connection failure between the wireless terminal and a certain AP. Note that the eNB may store and manage APs that serve as wireless LAN connection destinations for various wireless terminals when transmitting a wireless LAN connection instruction to the wireless terminals; in this case, the wireless terminals may not notify the eNB of the information related to the AP that served as the connection target until then.
Upon obtaining the information indicating whether the failure in wireless LAN connection is attributed to suspension of the wireless LAN communication functions of the wireless terminal, the eNB executes wireless LAN connection control between the wireless terminal and an AP based on that information. For example, when the obtained information indicates that the connection failure is attributed to suspension of the wireless LAN communication functions of the wireless terminal, the eNB instructs the wireless terminal and the AP to cut off the wireless LAN connection. This instruction can be, for example, an instruction for cancelling communication that is performed via LTE and a wireless LAN concurrently (e.g., LTE-WLAN Aggregation (LWA)). For example, the eNB can transmit the instruction for cancelling the wireless LAN connection to the AP using an RRC message. In this way, the eNB can be prevented from causing the wireless terminal to make an attempt for the wireless LAN connection continuously even though the wireless terminal has suspended the wireless LAN communication functions.
Upon obtaining the information indicating that the reason of the failure in the wireless LAN connection is not the suspension of the wireless LAN communication functions of the wireless terminal, the eNB can, for example, execute control for switching an AP that serves as a wireless LAN connection destination for the wireless terminal. In this case, the eNB instructs the AP that served as the connection destination for the wireless terminal until then to cut off connection to the wireless terminal, and also instructs an AP that serves as a connection destination from then on to establish connection to the wireless terminal. At this time, the establishment instruction from the eNB to the AP serving as the connection destination can be an instruction for starting processing for transmitting user data transferred from the eNB to the wireless terminal under control of the eNB. Note that this instruction can be issued to a WLAN Terminal (WT), which is a node placed between the eNB and the AP. A WT is connected to one or more APs, and upon receiving an instruction from the eNB, can transfer user data from the eNB to an AP connected to the WT and cause that AP serving as a transfer destination to transmit that user data to the wireless terminal.
Note that when the failure has occurred in the wireless LAN connection, the wireless terminal may transmit, to the eNB, information (e.g., BSSID) that specifies an AP that serves as a candidate for a switchover destination together with the information indicating the reason of the occurrence of the failure. At this time, for example, when a plurality of APs are connected to one WT, the wireless terminal may autonomously switch from the AP serving as the connection destination to another AP. In this case, after the switching, the wireless terminal may notify the eNB of information that specifies the AP serving as the switchover destination. In this case, in response to the received notification, the eNB can instruct the AP serving as the switchover destination to execute processing for transmitting user data transmitted by the eNB to the wireless terminal. At this time, the eNB can transmit information that specifies the wireless terminal to the AP.
Furthermore, when the wireless terminal switches the AP serving as the connection destination, the eNB can execute control for transferring user data that has already been transferred to the AP to the AP serving as the switchover destination. For example, the eNB can transmit, to the AP before the connection switching, an instruction for transferring user data that was unable to be transmitted to the wireless terminal to the AP after the switching. Here, when the AP before the connection switching and the AP after the switching are both connected to one WT, user data can be transferred via this one WT without involving the eNB. On the other hand, when a WT connected to the AP before the connection switching is different from a WT connected to the AP after the switching, user data can be transferred from the AP before the switching to the eNB, and then transferred from the eNB to the AP after the switching. Furthermore, when the AP before the connection switching is connected to a first WT and the AP after the switching is connected to a second WT that is different from the first WT, user data may be transferred via a line connecting between the first WT and the second WT without involving the eNB. On the other hand, when the wireless terminal cuts off the wireless LAN connection without switching the AP serving as the connection destination, the eNB can instruct the AP that was connected to the wireless terminal until then to return user data that was unable to be transferred to the wireless terminal to the eNB. Here, the wireless terminal can cut off the wireless LAN connection, for example, when the wireless LAN communication functions have been suspended as mentioned earlier, or when there is no appropriate AP that serves as the switchover destination.
The foregoing transfer processing eliminates the need to retain user data transferred from the eNB to an AP. Normally, there are many APs within a cell formed by one eNB; thus, if the eNB retains user data transferred to the APs until the completion of transmission to the wireless terminal, the capacity of a storage apparatus that is required by the eNB for the retaining purpose could be enormous. In contrast, the foregoing transfer processing can reduce the capacity of a storage apparatus included in the eNB.
Below is a detailed description of the components of a base station apparatus and a wireless terminal that execute the foregoing processing, and a flow of the processing executed by these components.
The base station apparatus and the wireless terminal, for example, control the communication apparatus 205 using the CPU 201 so that the base station apparatus and a wireless LAN AP perform communication with the wireless terminal. Furthermore, the base station apparatus, for example, controls the communication apparatus 205 using the CPU 201 to perform communication between the base station apparatus and an AP. Although
Note that the base station apparatus and the wireless terminal may include dedicated hardware that executes various functions; some parts may be executed by hardware, and other parts may be executed by a computer that causes programs to operate. Furthermore, all the functions may be executed by the computer and programs.
The transmission unit 301 transmits wireless signals to the wireless terminal, and the reception unit 302 receives wireless signals from the wireless terminal. Here, the wireless signals transmitted from the base station apparatus to the wireless terminal can include, for example, signals targeted at one wireless terminal, signals targeted at a plurality of wireless terminals, or signals targeted at all wireless terminals. On the other hand, the wireless signals transmitted from the wireless terminal to the base station apparatus are signals addressed to the base station apparatus. Furthermore, the transmission unit 301 transmits wired or wireless signals to the AP (or a WT placed between the eNB and the AP), and the reception unit 302 receives wired or wireless signals from the AP (or a WT placed between the eNB and the AP). Although each of the transmission unit 301 and the reception unit 302 serves as one functional unit that transmits/receives signals to/from the wireless terminal and the AP in the foregoing description, a transmission unit and a reception unit for the wireless terminal can exist separately from a transmission unit and a reception unit for the AP.
The information obtaining unit 303 obtains information related to a reason of the occurrence of a failure when the failure has occurred in connection between the wireless terminal and the wireless LAN AP. For example, the information obtaining unit 303 obtains the information related to the reason of the failure in the connection between the wireless terminal and the AP from the wireless terminal using a wireless signal. As mentioned earlier, the information obtained here can include, for example, information indicating whether the failure in the wireless LAN connection is attributed to suspension of wireless LAN communication functions of the wireless terminal. This information can also include information (e.g., BSSID) for specifying an AP that served as a connection destination until then. Furthermore, when this information indicates that the reason of the failure is not the suspension of the wireless LAN communication functions and the AP serving as the connection destination for the wireless terminal is to be switched, this information can include information that specifies an AP that serves as a connection switchover destination. The WLAN connection control unit 304 executes connection control for the wireless terminal via a wireless LAN. Note that when, for example, the AP serving as the connection destination for the wireless terminal is to be switched, this connection control can include control for transferring, to the AP serving as the connection switchover destination, user data that has not been transmitted from the AP to the wireless terminal.
The transmission unit 401 transmits wireless signals to the eNB and the AP, and the reception unit 402 receives wireless signals from the eNB and the AP. Note that the wireless terminal may include separate transmission units 401 and separate reception units 402 for communication with the eNB and for communication with the AP. In response to an instruction from the eNB, the transmission unit 401 and the reception unit 402 perform wireless LAN communication, in addition to LTE communication, or end the wireless LAN communication. Note that the transmission unit 401 and the reception unit 402 include a portion for LTE communication functions in association with the eNB, and a portion for wireless LAN communication functions in association with the AP. The wireless terminal can suspend the LTE communication functions and the wireless LAN communication functions separately and independently of each other.
The communication function monitoring unit 403 monitors the transmission unit 401 and the reception unit 402, and when, for example, a failure has occurred in the wireless LAN communication, determines where the wireless LAN communication functions have been suspended. Note that when it is determined that the wireless LAN communication functions have not been suspended, the communication function monitoring unit 403 can determine whether the transmission unit 401 and the reception unit 402 have connected to (or whether they are attempting to connect to) an AP that is different from an AP to which they were connected until then without receiving an instruction from the eNB. When the transmission unit 401 and the reception unit 402 have connected to the different AP, this AP is specified.
When the failure has occurred in the wireless LAN communication, the information notification unit 404 generates information of which the eNB is to be notified with reference to a result of the determination made by the communication function monitoring unit 403 as to whether the wireless LAN communication functions have been suspended. That is to say, when the failure has occurred in the wireless LAN communication, the information notification unit 404 generates information indicating whether the reason of the failure is the suspension of the wireless LAN communication functions of the wireless terminal. The information notification unit 404 causes the transmission unit 401 to transmit the generated information. Note that when the failure has occurred in the wireless LAN communication and the reason of the failure is not the suspension of the wireless LAN communication functions of the wireless terminal, if there has been a change in an AP serving as a connection destination without an instruction from the eNB, the information notification unit 404 can notify the eNB of information that specifies this AP.
In the foregoing manner, when a failure has occurred in connection between the wireless terminal and the AP, the eNB obtains information indicating whether the reason of the occurrence of the failure is suspension of the wireless LAN communication functions of the wireless terminal, and controls the wireless LAN connection of the wireless terminal. In this way, the eNB can be prevented from causing the wireless terminal to make an attempt for connection to another AP continuously even though the wireless LAN communication functions of the wireless terminal have been suspended. Furthermore, the eNB can be prevented from causing the wireless terminal to needlessly cut off the wireless LAN connection even though the wireless LAN communication functions of the wireless terminal have not been suspended.
Using
In this case, as the wireless terminal can switch from connection to the AP1 to connection to the AP2, the eNB notifies the wireless terminal of an instruction for changing an AP serving as a connection destination (step S504). Although
It will be assumed that, thereafter, the wireless terminal has suspended the wireless LAN communication functions (step S509). Once the wireless terminal has suspended the wireless LAN communication functions, a failure occurs in the wireless LAN communication that the wireless terminal has established with the AP2 at this point (step S510). In this case also, the wireless terminal notifies the eNB of the occurrence of the failure in the wireless LAN communication, and the suspension of the wireless LAN communication functions of the wireless terminal as the reason of the occurrence of the failure (step S511). Upon obtaining this report, the eNB determines whether the reason of the communication failure is the suspension of the wireless LAN communication functions of the wireless terminal (step S512). In this case, as the reason of the communication failure is the suspension of the wireless LAN communication functions of the wireless terminal, the eNB instructs the wireless terminal to stop the wireless LAN connection (step S513). Similarly, the eNB also causes the AP2 to stop the wireless LAN communication with the wireless terminal (step S514). Note that at this time, the eNB can instruct the AP2 to return, to the eNB, user data that has not been transmitted to the wireless terminal. This processing will be described later. Thereafter, the wireless terminal transmits a report indicating the completion of wireless LAN disconnection to the eNB (step S515).
Using
Once the connection destination has been switched, the wireless terminal transmits, to the eNB, a report of the wireless LAN connection failure including information that specifies the AP2 serving as the connection destination after the switching (step S603). Upon receiving the report, the eNB specifies the connection destination for the wireless terminal after the switching based on the report (step S604). In this case, as the wireless terminal is already connected to the AP2, the eNB can transmit, to the AP2, an instruction for transferring user data transferred by the eNB to the wireless terminal without transmitting an instruction for switching the connection destination to the wireless terminal, for example. Furthermore, the eNB can transmit, to the AP1 that served as the wireless LAN connection destination for the wireless terminal before the switching, control information such as an instruction for transferring untransmitted user data to the AP2 serving as the connection destination after the switching (step S605).
When the wireless terminal has established the wireless LAN connection under control of the eNB, it is not permitted to voluntarily determine wireless LAN disconnection without an instruction from the eNB in some cases. The foregoing processing can prevent the eNB from continuously waiting for the establishment of wireless LAN connection even though the wireless terminal has suspended the wireless LAN communication functions and cannot perform wireless LAN communication. Furthermore, as the eNB can quickly determine wireless LAN disconnection in accordance with a report, user data that has been transferred to an AP but has not been transmitted to the wireless terminal can be quickly retrieved and transmitted to the wireless terminal.
Using
As described above, in the present embodiment, when a failure has occurred in connection in a second system (e.g., a wireless LAN) while a wireless terminal is performing communication in the second system under control of a first system (e.g., LTE), a base station in the first system obtains the reason of the failure. In this way, the base station in the first system can appropriately execute connection control involving, for example, whether to make the wireless terminal continue communication in the second system thereafter.
Note that the aforementioned eNB may be replaced by some sort of control apparatus. That is to say, the eNB need not be a base station apparatus as long as it is an apparatus that can appropriately execute connection control on the wireless LAN (second system) side in accordance with the reason of the occurrence of a failure in a wireless LAN. Similarly, the aforementioned terms are used for the sake of explanation, and are not intended to limit the scope of the present invention to processing associated with simultaneous communication under LTE and a wireless LAN.
The present invention is not limited to the above embodiment and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made.
Number | Date | Country | Kind |
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2015-159124 | Aug 2015 | JP | national |
This application is a Continuation of International Patent Application No. PCT/JP2016/064956, filed May 20, 2016, which claims the benefit of Japanese Patent Application No. 2015-159124, filed Aug. 11, 2015, both of which are hereby incorporated by reference herein in their entirety.
Number | Date | Country | |
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Parent | PCT/JP2016/064956 | May 2016 | US |
Child | 15891845 | US |