JP2017163347A - Communication apparatus, system, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication apparatus, system and program, capable of achieving the acceleration of migration during handover.SOLUTION: The communication apparatus includes a data acquisition part. The data acquisition part acquires cash data stored in a handover source of a radio communication apparatus from an acquisition source. The acquisition source is determined on the basis of cash information including an identifier of the cash data.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a communication device, a system, and a program.

  Conventionally, a handover technique is known in which an access point (hereinafter referred to as “AP”) to which a wireless communication terminal is connected wirelessly is switched to another AP having a better communication environment in accordance with the movement of the wireless communication terminal. .

  When handover is performed between APs having a cache function, some or all of cache data may be migrated between APs at the time of handover in order to reduce communication latency and improve throughput.

  However, if the line between APs is congested during handover, communication latency may increase and throughput may decrease due to congestion or migration delay.

U.S. Pat. No. 8,576,756

  Provided are a communication device, a system, and a program in which migration at the time of handover is accelerated.

  A communication apparatus according to an embodiment includes a data acquisition unit. The data acquisition unit acquires the cache data stored in the handover source of the wireless communication apparatus from the acquisition source. The acquisition source is determined based on cache information including an identifier of cache data.

The figure which shows an example of the function structure of AP which concerns on 1st Embodiment. The figure which shows an example of a cache information list. The figure which shows an example of a computer. The flowchart which shows an example of operation | movement of AP at the time of reception of a data request. The figure which shows an example of the communication system which concerns on 1st Embodiment. The flowchart which shows an example of operation | movement of AP at the time of handover execution in 1st Embodiment. The figure which shows an example of an acquisition source list. The flowchart which shows an example of the acquisition source determination method using RTT. The flowchart which shows an example of the acquisition source determination method using a throughput. The flowchart which shows an example of the acquisition source determination method using RTT, throughput, and data size. The flowchart which shows an example of operation | movement of AP at the time of handover execution in 2nd Embodiment. The flowchart which shows an example of the acquisition source determination method using a throughput and a vacant bandwidth. The flowchart which shows an example of operation | movement of AP at the time of handover execution in 3rd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A communication apparatus according to the first embodiment will be described with reference to FIGS. In the following, it is assumed that the communication apparatus according to the present embodiment is an AP.

  The AP according to the present embodiment is connected to another communication node via a network. Other communication nodes include other APs and servers. The server is, for example, a web server, a data server, or an application server, but is not limited thereto.

  The AP can be connected to a wireless communication terminal (hereinafter referred to as “terminal”) wirelessly. The terminal is a mobile phone, a smartphone, a tablet terminal, or a notebook computer, but is not limited thereto.

  Further, the AP has a cache function and a handover function. The cache function is a function for the AP to store (cache) data stored in the server. The handover function is a function for switching the AP connected to the terminal.

  First, the functional configuration of the AP according to the present embodiment will be described. FIG. 1 is a diagram illustrating an example of a functional configuration of an AP according to the present embodiment. 1 includes a data acquisition unit 1, an acquisition source determination unit 2, a cache transmission unit 3, a storage unit 4, a cache information notification unit 5, and an interface unit 6.

  The data acquisition unit 1 transmits a data request to another communication node, acquires predetermined data from the other communication node, and caches the acquired data. That is, the data acquisition unit 1 writes data acquired from other communication nodes in the storage unit 4 as cache data.

  The acquisition source determination unit 2 determines a communication node as an acquisition source from which the data acquisition unit 1 acquires data based on the cache information list notified from another AP and the history information of the own device.

  The cache information list is a list including one or more cache information. The cache information refers to data cached by the AP, that is, information related to cache data stored in the storage unit 4. The cache information includes an identifier for uniquely identifying cache data and cache data attribute information. The identifier of the cache data is, for example, a URL (Uniform Resource Locator), but is not limited thereto. In the cache information list, when the order of the cache data is sorted by domain or path, it is possible to use a relative path as an identifier of the cache data. Hereinafter, a case where the identification formula is a URL will be described as an example.

  The attribute information includes at least one of throughput when the AP acquires cache data, RTT (round trip time), acquisition date and time (update date and time), time required for acquisition, and data size of the cache data. The throughput when acquiring cache data may be the average throughput when acquiring cache data or the maximum throughput.

  FIG. 2 is a diagram illustrating an example of the cache information list. Each record in FIG. 2 corresponds to cache information of each cache data. The cache information list of FIG. 2 includes cache information of three cache data. Each cache information includes the URL of the cache data, the throughput and RTT when the cache data is acquired, and the data size of the cache data. Cache data update date and time (acquisition date and time).

  The cache information may include an IP address in addition to the above-described URL (identifier) and attribute information.

  The history information is arbitrary information regarding the communication history of the AP. The history information includes information regarding a communication history between the AP and another communication node and information regarding a communication history between the AP and the terminal. The history information includes the URL, domain name, IP address of the communication destination, and attribute information (throughput, RTT, data size, update date, etc.). The cache data corresponding to the cache information included in the cache information list is stored in the storage unit 4, whereas the cache data corresponding to the cache information included in the history information is stored in the storage unit 4. Not necessarily.

  The AP according to the present embodiment stores its own cache information list and history information in the storage unit 4.

  The cache transmission unit 3 reads the cache data of its own device stored in the storage unit 4 and transmits the read cache data to another communication node.

  The storage unit 4 stores cache data, a cache information list, and history information.

  The cache information notification unit 5 notifies the cache information of its own device to other APs.

  The interface unit 6 communicates with other communication nodes via a network. The interface unit 6 communicates with the terminal wirelessly. Communication between the AP according to the present embodiment and other communication nodes and terminals is performed via the interface unit 6.

  Next, the hardware configuration of the AP according to the present embodiment will be described. The AP according to the present embodiment is configured by a computer 100. The computer 100 includes a server, a client, a microcomputer, a general-purpose computer, and the like.

  FIG. 3 is a diagram illustrating an example of the computer 100. The computer 100 in FIG. 3 includes a processor 101, an input device 102, a display device 103, a communication device 104, and a storage device 105. The processor 101, the input device 102, the display device 103, the communication device 104, and the storage device 105 are connected to each other via a bus 106.

  The processor 101 is an electronic circuit including a control device and a calculation device of the computer 100. Examples of the processor 101 include a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, an application-specific integrated circuit, a field programmable gate array (FPGA), and a program Possible logic circuits (PLDs) and combinations thereof can be used.

  The processor 101 performs arithmetic processing based on data or a program input from each device (for example, the input device 102, the communication device 104, and the storage device 105) connected via the bus 106, and outputs a calculation result and a control signal. And output to each device (for example, the display device 103, the communication device 104, and the storage device 105) connected via the bus 106. Specifically, the processor 101 executes an OS (operating system) of the computer 100, a communication program, and the like, and controls each device constituting the computer 100.

  The communication program is a program that causes the computer 100 to realize each functional configuration of the AP. The communication program is stored in a tangible computer-readable storage medium that is not temporary. The storage medium is, for example, an optical disk, a magneto-optical disk, a magnetic disk, a magnetic tape, a flash memory, or a semiconductor memory, but is not limited thereto. When the processor 101 executes the communication program, the computer 100 functions as an AP.

  The input device 102 is a device for inputting information to the computer 100. The input device 102 is, for example, a keyboard, a mouse, and a touch panel, but is not limited thereto.

  The display device 103 is a device for displaying images and videos. The display device 103 is, for example, an LCD (liquid crystal display), a CRT (CRT), and a PDP (plasma display), but is not limited thereto.

  The communication device 104 is a device for the computer 100 to communicate with an external device wirelessly or by wire. The communication device 104 is, for example, a modem, a hub, and a router, but is not limited thereto. The function of the interface unit 6 is realized by the communication device 104.

  The storage device 105 is a storage medium that stores the OS of the computer 100, a communication program, data necessary for executing the communication program, data generated by executing the communication program, and the like. The storage device 105 includes a main storage device and an external storage device. The main storage device is, for example, a RAM, a DRAM, or an SRAM, but is not limited thereto. The external storage device is, for example, a hard disk, an optical disk, a flash memory, and a magnetic tape, but is not limited thereto. The storage unit 4 includes a storage device 105.

  Note that the computer 100 may include one or more processors 101, input devices 102, display devices 103, communication devices 104, and storage devices 105, and is connected to peripheral devices such as printers and scanners. Also good.

  The AP may be configured by a single computer 100 or may be configured as a system including a plurality of computers 100 connected to each other.

  Furthermore, the communication program may be stored in advance in the storage device 105 of the computer 100, may be stored in a storage medium external to the computer 100, or may be uploaded on the Internet. In any case, the function of the AP is realized by installing the communication program in the computer 100 and executing it.

  Next, the operation of the AP according to this embodiment will be described. Hereinafter, operations of the AP when receiving a data request from the terminal and when executing a handover will be described.

(When receiving a data request from the terminal)
First, the operation when receiving a data request will be described. FIG. 4 is a flowchart showing an example of the operation of the AP when receiving a data request from the terminal.

  When the terminal connected to the AP transmits a data request, the AP interface unit 6 receives the transmitted data request (step S1). Hereinafter, the data requested by the data request is referred to as request data. The interface unit 6 notifies the URL of the request data to the acquisition source determination unit 2 and the cache transmission unit 3.

  Next, the acquisition source determination unit 2 reads the cache information list from the storage unit 4, and refers to the read cache information list to determine whether the request data has been cached (step S2). That is, the acquisition source determination unit 2 determines whether the request data is stored in the storage unit 4 as cache data. The acquisition source determination unit 2 performs this determination by comparing the URL of the cache data included in each cache information with the URL of the request data.

  When cache information having a URL that matches the URL of the request data is not included in the cache information list, that is, when the request data is not cached (NO in step S2), the acquisition source determination unit 2 The URL is notified to the data acquisition unit 1.

  Subsequently, the data acquisition unit 1 transmits a data request to the server storing the request data, acquires the request data (step S3), and writes the acquired request data in the storage unit 4 (step S4). Thereby, the request data is cached in the AP. When the request data is cached, the acquisition source determination unit 2 updates the cache information list and history information stored in the storage unit 4 (step S5).

  Thereafter, the cache transmission unit 3 reads the cache data (cached request data) corresponding to the URL notified from the interface unit 6 from the storage unit 4 (step S6), and transmits the read cache data to the terminal (step S6). S7).

  On the other hand, when cache information having a URL that matches the URL of the request data is included in the cache information list, that is, when the request data has already been cached (YES in step S2), the cache transmission unit 3 performs the interface unit 6 The cache data (cached request data) corresponding to the URL notified from is read from the storage unit 4 (step S6), and the read cache data is transmitted to the terminal (step S7).

  With the above processing, the cache function of the AP according to the present embodiment is realized. With this cache function, the AP can transmit the requested data to the terminal without accessing the server when the cached data is requested. Therefore, communication latency between the AP and the terminal can be reduced.

  Note that the AP according to the present embodiment may cache all request data requested from the terminal, or may selectively cache some request data. As a method of selecting request data to be cached, for example, a method of caching request data requested from a terminal a predetermined number of times or more can be considered. However, the method of selecting request data to be cached is not limited to this, and any known method can be used.

(When executing handover)
Next, the operation of the AP at the time of executing handover will be described. FIG. 5 is a diagram illustrating an example of a communication system according to the present embodiment. The communication system of FIG. 5 includes two APs according to the present embodiment, a server, and a terminal. The two APs and the server are connected via a network. One AP is wirelessly connected to the terminal.

  Hereinafter, as illustrated in FIG. 5, a case where handover (HO) is performed between two APs will be described as an example. In addition, when performing handover, an AP that is a handover source, that is, an AP that is disconnected from a terminal by handover is referred to as a source AP. An AP that is a handover destination when performing a handover, that is, an AP that is connected to a terminal by a handover is called a destination AP. By the handover, the terminal can switch the connection from the source AP to the destination AP.

  FIG. 6 is a flowchart showing an example of the operation of the AP at the time of executing handover in the present embodiment. When the original AP receives a handover start request from the terminal, the handover process is started. Following this handover process, the following migration process is started.

  When the migration process is started, first, the cache information notifying unit 5 of the original AP reads the cache information list from the storage unit 4, and notifies the read cache information list to the destination AP designated by the start request (step). S8). At this time, the cache information notifying unit 5 of the source AP may notify the destination AP of the entire cache information list, or selectively notifies the destination AP of a part related to the terminal in the cache information list. Also good.

  When notified of the cache information list of the original AP, the acquisition source determination unit 2 of the previous AP selects one cache information from the notified cache information list (step S9). The acquisition source determination unit 2 may select the cache information at random or may select the cache information in the order arranged in the cache information list.

  Next, the acquisition source determination unit 2 determines the acquisition source of the cache data corresponding to the selected cache information from other communication nodes (step S10). Specifically, the acquisition source determination unit 2 determines whether to acquire cache data from the original AP or from a server that stores the cache data. At this time, the acquisition source determination unit 2 determines the acquisition source based on the cache information so that the acquisition time of the cache data is shortened. That is, the acquisition source determination unit 2 determines a communication node (original AP or server) that can acquire cache data at high speed as an acquisition source. The method for determining the acquisition source will be described later in detail.

  When the acquisition source determination unit 2 determines the acquisition source of the cache data, the acquisition source determination unit 2 updates the acquisition source list (step S11). The acquisition source list is a list including one or more acquisition source information. The acquisition source information is information including the URL of the cache data and the acquisition source of the cache data determined by the acquisition source determination unit 2.

  FIG. 7 is a diagram illustrating an example of the acquisition source list. Each record in FIG. 7 corresponds to each acquisition source information. The acquisition source list in FIG. 7 includes three pieces of acquisition source information. Each acquisition source information includes a cache data URL and a cache data acquisition source (source AP or server). For example, in the example of FIG. 7, the acquisition source of the cache data corresponding to the record on the first line is the original AP.

  Each time the acquisition source determination unit 2 determines the acquisition source of one cache data, the acquisition source determination unit 2 adds the corresponding acquisition source information to the acquisition source list and updates the acquisition source list.

  After updating the acquisition source list, the acquisition source determination unit 2 determines whether the acquisition source of all cache data corresponding to the cache information list of the original AP has been determined (step S12). If there is cache data whose acquisition source has not been determined (NO in step S12), the acquisition source determination unit 2 selects the next cache information (step S9). On the other hand, when the acquisition source of all the cache data is determined (YES in step S12), the acquisition source determination unit 2 notifies the data acquisition unit 1 of the acquisition source list.

  Subsequently, the data acquisition unit 1 transmits a data request according to the notified acquisition source list, and acquires each cache data from each acquisition source (step S13). Here, the cache data X whose acquisition source is the original AP and the cache data Y whose acquisition source is the server are considered.

  The data acquisition unit 1 transmits a data request for requesting the cache data X to the original AP. When the original AP receives this data request, the cache transmission unit 3 of the original AP reads the cache data X from the storage unit 4 of the original AP, and transmits the read cache data to the destination AP. As a result, the data acquisition unit 1 of the destination AP can acquire the cache data X from the source AP.

  The data acquisition unit 1 transmits a data request for requesting the cache data Y to a server that stores the cache data Y. When the server receives this data request, it sends cache data Y to the destination AP. As a result, the data acquisition unit 1 of the destination AP can acquire the cache data Y from the server.

  The data acquisition unit 1 of the previous AP writes the cache data acquired in this way into the storage unit 4 (step S14). As a result, the cache data corresponding to the cache information list of the original AP is cached in the storage unit 4 of the previous AP. When the writing of the cache data is completed, the acquisition source determination unit 2 of the previous AP updates the cache information list and history information of the own device stored in the storage unit 4 (step S15).

  Through the above processing, the cache data of the original AP can be migrated to the destination AP. In the present embodiment, the destination AP does not have to acquire cache data cached by its own device from other communication nodes. Such processing can be realized by the same method as in step S2. Specifically, after selecting the cache information, the acquisition source determination unit 2 of the destination AP determines whether the cache data corresponding to the selected cache information has been cached. If the cache data has been cached, the acquisition source determination unit 2 does not determine the acquisition source. The next cache information may be selected. Thereby, cache data to be acquired can be reduced, and migration can be speeded up.

  Further, in the above description, the destination AP starts acquiring each cache data after the acquisition source of all cache data is determined. However, every time the acquisition source of one cache data is determined, Data acquisition may be started.

  If the actual throughput when the data acquisition unit 1 of the destination AP acquires cache data from the server is slower than the throughput of the cache information, the data acquisition unit 1 changes the acquisition source from the server to the original AP. May be.

  Next, a method for determining the acquisition source of cache data by the acquisition source determination unit 2 of the destination AP will be described. FIG. 8 is a flowchart illustrating an example of an acquisition source determination method using RTT. This flowchart corresponds to the internal processing of step S10 in FIG. In the following, it is assumed that the cache information includes RTT.

  First, the acquisition source determination unit 2 of the previous AP reads the history information from the storage unit 4, and compares the update date / time of the cache information with the update date / time of the history information corresponding to the cache information (step S16). The history information corresponding to the cache information here is history information indicating the RTT when the destination AP communicates with the server storing the cache data. The acquisition source determination unit 2 of the previous AP may use history information including a URL that matches the URL of the cache information as history information corresponding to the cache information, or a part of the URL (protocol or domain) of the cache information. (Name, port number, path, etc.) and history information including an IP address may be used.

  When the update date / time of the history information is newer than the update date / time of the cache information (YES in step S16), the acquisition source determination unit 2 employs the RTT of the history information as the inter-server RTT (step S17). On the other hand, when the history information update date / time is not newer than the cache information update date / time (NO in step S16), the acquisition source determination unit 2 adopts the cache information RTT as the inter-server RTT (step S18).

  The inter-server RTT here is an RTT that is expected when the destination AP acquires cache data from the server. The RTT of the cache information is an RTT when the original AP acquires cache data from the server, and the RTT of the history information is an RTT when the destination AP communicates with the server. The acquisition source determination unit 2 adopts the RTT with the newest update date as the inter-server RTT.

  When history information corresponding to the cache information is not stored in the storage unit 4, the acquisition source determination unit 2 may adopt the RTT of the cache information as the inter-server RTT. It is also possible to omit step S16 and adopt the RTT of the cache information as the inter-server RTT.

  Next, the acquisition source determination unit 2 compares the inter-server RTT and the inter-AP RTT (step S19). The inter-AP RTT here is an RTT that is expected when the previous AP acquires cache data from the original AP. As the inter-AP RTT, for example, the RTT when the destination AP receives the cache information list from the source AP can be used.

  When the inter-AP RTT is shorter than the inter-server RTT (YES in step S19), the acquisition source determination unit 2 determines the acquisition source of the cache data as the original AP (step S20). On the other hand, when the inter-AP RTT is equal to or greater than the inter-server RTT (NO in step S19), the acquisition source determination unit 2 determines the acquisition source of the cache data as the server (step S21).

  By determining the acquisition source in this way, the acquisition source determination unit 2 can determine a communication node having a shorter RTT when acquiring cache data as the acquisition source of cache data.

  As described above, the AP according to the present embodiment determines the acquisition source of the cache data so that the acquisition time of the cache data is shortened when operating as the destination AP at the time of executing the handover. By determining the cache data acquisition source in this manner, the time required for the destination AP to acquire the cache data can be shortened, and the migration of the cache data from the source AP to the destination AP at the time of handover can be accelerated.

  Note that the acquisition source determination unit 2 can determine the acquisition source of the cache data using other attribute information instead of the RTT. As an example, a case will be described in which an acquisition source is determined using throughput instead of RTT.

  FIG. 9 is a flowchart illustrating an example of an acquisition source determination method using throughput. This flowchart corresponds to the internal processing of step S10 in FIG. In the following, it is assumed that the cache information includes throughput.

  First, the acquisition source determination unit 2 of the previous AP reads the history information from the storage unit 4, and compares the update date / time of the cache information with the update date / time of the history information corresponding to the cache information (step S22). The history information corresponding to the cache information here is history information indicating the throughput when the destination AP and the server storing the cache data communicate with each other. The acquisition source determination unit 2 of the previous AP may use history information including a URL that matches the URL of the cache information as history information corresponding to the cache information, or a part of the URL (protocol or domain) of the cache information. (Name, port number, path, etc.) and history information including an IP address may be used.

  When the update date / time of the history information is newer than the update date / time of the cache information (YES in step S22), the acquisition source determination unit 2 employs the throughput of the history information as the inter-server throughput (step S23). On the other hand, when the history information update date is not newer than the cache information update date (NO in step S22), the acquisition source determination unit 2 adopts the cache information throughput as the inter-server throughput (step S24).

  The inter-server throughput here is a throughput that is expected when the destination AP acquires cache data from the server. The throughput of cache information is the throughput when the original AP acquires cache data from the server, and the throughput of history information is the throughput when the destination AP communicates with the server. The acquisition source determination unit 2 uses the throughput with the newest update date as the inter-server throughput.

  When history information corresponding to the cache information is not stored in the storage unit 4, the acquisition source determination unit 2 may adopt the throughput of the cache information as the inter-server throughput. It is also possible to omit step S22 and adopt the cache information throughput as the inter-server throughput.

  Next, the acquisition source determination unit 2 compares the inter-server throughput with the inter-AP throughput (step S25). The inter-AP throughput here is the throughput expected when the destination AP acquires cache data from the source AP. As the inter-AP throughput, for example, the throughput when the destination AP receives the cache information list from the source AP can be used.

  If the inter-AP throughput is equal to or less than the inter-server throughput (NO in step S25), the acquisition source determination unit 2 determines the acquisition source of cache data as the original AP (step S26). On the other hand, when the inter-AP throughput is larger than the inter-server throughput (YES in step S25), the acquisition source determination unit 2 determines the acquisition source of cache data to the server (step S27).

  By determining the acquisition source in this way, the acquisition source determination unit 2 can determine a communication node having a higher throughput when acquiring cache data as the acquisition source of cache data. As a result, the time required for the destination AP to acquire the cache data can be shortened, and the migration of the cache data from the source AP to the destination AP at the time of handover can be accelerated.

  Furthermore, the acquisition source determination unit 2 can also determine an acquisition source using a plurality of attribute information. As an example, a case where the acquisition source is determined using RTT, throughput, and data size will be described.

  FIG. 10 is a flowchart illustrating an example of an acquisition source determination method using RTT, throughput, and data size. This flowchart corresponds to the internal processing of step S10 in FIG. In the following, it is assumed that the cache information includes RTT, throughput, and data size.

  First, the acquisition source determination unit 2 of the destination AP compares the data size of the cache data with a preset data size threshold (step S28). When the data size of the cache data is larger than the threshold value (YES in step S28), the acquisition source determination unit 2 determines the acquisition source based on the throughput. The acquisition source determination method based on the throughput (steps S22 to S27) is as described above. On the other hand, when the data size of the cache data is equal to or smaller than the threshold (NO in step S28), the acquisition source determination unit 2 determines the acquisition source based on the RTT. The acquisition source determination method based on the RTT (steps S16 to S21) is as described above.

  In general, the larger the data size of cache data, the greater the effect of throughput on the time required to acquire cache data, and the smaller the data size of cache data, the greater the effect of RTT on the time required to acquire cache data. Therefore, as described above, when the data size of the cache data is large, the acquisition source is determined based on the throughput, and when the data size of the cache data is small, the acquisition source is determined based on the RTT. The time required for acquiring cache data can be further reduced.

(Second Embodiment)
A communication device according to the second embodiment will be described with reference to FIGS. 11 and 12. In the first embodiment, the method by which the acquisition source determination unit 2 of the destination AP determines the acquisition source based on the cache information has been described. In the present embodiment, a method will be described in which the acquisition source determination unit 2 of the destination AP determines the acquisition source of cache data using the free bandwidth between the two APs. In the present embodiment, the functional configuration and hardware configuration of the AP are the same as those in the first embodiment.

  FIG. 11 is a flowchart showing an example of the operation of the AP at the time of executing handover in the present embodiment. When the original AP receives a handover start request from the terminal, the handover process is started. Following this handover process, the following migration process is started.

  When the migration process is started, first, the cache information notification unit 5 of the source AP notifies the destination AP of the cache information and the free bandwidth (step S28). The notification of the cache information list is the same as in step S8.

  The free bandwidth is a communication bandwidth that can be used between the original AP and the destination AP. The cache information notification unit 5 of the original AP sets the transmission speed from the original AP to the destination AP, the average value (average speed) of the transmission speed, the maximum value (maximum speed) of the transmission speed, the scheduled bandwidth, the used bandwidth, etc. Based on this, the current available bandwidth is calculated and the cache information list is notified to the destination AP. Details of the scheduled bandwidth and the used bandwidth will be described later.

  When notified of the cache information list of the original AP and the free bandwidth, the acquisition source determination unit 2 of the destination AP selects one piece of cache information from the notified cache information list (step S30). The acquisition source determination unit 2 may select the cache information at random or may select the cache information in the order arranged in the cache information list.

  Next, the acquisition source determination unit 2 determines an acquisition source of cache data corresponding to the selected cache information from other communication nodes (step S31). In the present embodiment, the acquisition source determination unit 2 determines the acquisition source based on the available bandwidth notified from the original AP. The method for determining the acquisition source will be described later in detail.

  When the acquisition source determination unit 2 determines the acquisition source of the cache data, the acquisition source determination unit 2 updates the acquisition source list (step S32). The acquisition source list is as described above. Each time the acquisition source determination unit 2 determines the acquisition source of one cache data, the acquisition source determination unit 2 adds the corresponding acquisition source information to the acquisition source list and updates the acquisition source list.

  After updating the acquisition source list, the acquisition source determination unit 2 determines whether the acquisition source of all cache data corresponding to the cache information list of the original AP has been determined (step S33). If there is cache data whose acquisition source is undetermined (NO in step S33), the acquisition source determination unit 2 selects the next cache information (step S30). On the other hand, when the acquisition source of all the cache data is determined (YES in step S33), the acquisition source determination unit 2 notifies the data acquisition unit 1 of the acquisition source list.

  In this embodiment, after determining the acquisition source of all the cache data, the acquisition source determination unit 2 of the destination AP calculates the scheduled use bandwidth and notifies the cache information notification unit 5 of the source AP (step S34). The planned use band is a band that the destination AP is scheduled to use to acquire cache data from the source AP. As the planned use band, for example, the total value of the throughput of the cache data that the destination AP acquires from the original AP (cache data whose acquisition source is the original AP) is calculated.

  When the cache information notifying unit 5 of the original AP is notified of the scheduled use bandwidth from the acquisition source determining unit 2 of the previous AP, the cache information notifying unit 5 updates the free bandwidth based on the planned use bandwidth. Specifically, the free bandwidth of the original AP is reduced by the amount that is scheduled to be used.

  Subsequently, the data acquisition unit 1 transmits a data request according to the notified acquisition source list, and acquires each cache data from each acquisition source (step S35). The method for acquiring cache data from each acquisition source is as described above.

  The data acquisition unit 1 of the previous AP writes the cache data acquired in this way in the storage unit 4 (step S36). As a result, the cache data corresponding to the cache information list of the original AP is cached in the storage unit 4 of the previous AP. When the writing of the cache data is completed, the acquisition source determination unit 2 of the previous AP updates the cache information list and history information of the own device stored in the storage unit 4 (step S37).

  In the present embodiment, the acquisition source determination unit 2 of the destination AP updates the cache information list and history information of its own device, calculates the used bandwidth, and notifies the cache information notification unit 5 of the source AP (step S38). ). The used band is a band used by the destination AP to acquire cache data from the source AP. The acquisition source determination unit 2 may notify the same value as the planned use band as the used band.

  When the cache information notifying unit 5 of the original AP is notified of the used bandwidth from the acquisition source determining unit 2 of the previous AP, the cache information notifying unit 5 updates the free bandwidth based on the used bandwidth. Specifically, the free bandwidth of the original AP is increased by the used bandwidth.

  Through the above processing, the cache data of the original AP can be migrated to the destination AP. Further, by updating the free bandwidth of the original AP during the migration process, the above-described migration process can be executed between the original AP and a plurality of destination APs.

  In the present embodiment, the destination AP does not have to acquire cache data cached by its own device from other communication nodes. Such processing can be realized by the same method as in step S2.

  Further, in the above description, the destination AP starts acquiring each cache data after the acquisition source of all cache data is determined. However, every time the acquisition source of one cache data is determined, Data acquisition may be started.

  If the actual throughput when the data acquisition unit 1 of the destination AP acquires cache data from the server is slower than the throughput of the cache information, the data acquisition unit 1 changes the acquisition source from the server to the original AP. May be.

  Further, the acquisition source determination unit 2 of the destination AP may calculate the used bandwidth and notify the cache information notification unit 5 of the source AP every time acquisition of one cache data is completed.

  FIG. 12 is a flowchart illustrating an example of an acquisition source determination method using throughput and free bandwidth. This flowchart corresponds to the internal processing of step S31 in FIG. In the following, it is assumed that the cache information includes throughput.

  First, the acquisition source determination unit 2 of the previous AP reads the history information from the storage unit 4, and compares the update date / time of the cache information with the update date / time of the history information corresponding to the cache information (step S39). The history information corresponding to the cache information here is history information indicating the throughput when the destination AP and the server storing the cache data communicate with each other. The acquisition source determination unit 2 of the previous AP may use history information including a URL that matches the URL of the cache information as history information corresponding to the cache information, or a part of the URL (protocol or domain) of the cache information. (Name, port number, path, etc.) and history information including an IP address may be used.

  When the update date / time of the history information is newer than the update date / time of the cache information (YES in step S39), the acquisition source determination unit 2 adopts the throughput of the history information as the inter-server throughput (step S40). On the other hand, when the history information update date is not newer than the cache information update date (NO in step S39), the acquisition source determination unit 2 adopts the cache information throughput as the inter-server throughput (step S41). The inter-server throughput is as described above.

  When history information corresponding to the cache information is not stored in the storage unit 4, the acquisition source determination unit 2 may adopt the throughput of the cache information as the inter-server throughput. It is also possible to omit step S39 and adopt the cache information throughput as the inter-server throughput.

  Next, the acquisition source determination unit 2 compares the inter-server throughput with the free bandwidth notified from the original AP (step S42). If the available bandwidth is larger than the server-to-server throughput (YES in step S42), the acquisition source determination unit 2 determines the acquisition source of cache data as the original AP (step S43). Then, the acquisition source determination unit 2 updates the free bandwidth notified from the original AP (step S44). Specifically, the acquisition source determination unit 2 reduces the free bandwidth by the amount of the cache data throughput.

  On the other hand, when the available bandwidth is equal to or less than the server-to-server throughput (NO in step S42), the acquisition source determination unit 2 determines the acquisition source of cache data to the server (step S45).

  By determining the acquisition source in this way, the acquisition source determination unit 2 can set the used bandwidth used for acquiring cache data from the source AP within the range of the free bandwidth. Thereby, it is possible to suppress a delay in acquiring cache data from the original AP, and to shorten the time required for the destination AP to acquire cache data.

(Third embodiment)
A communication apparatus according to the third embodiment will be described with reference to FIG. In the above embodiment, the method by which the acquisition source determination unit 2 of the destination AP determines the acquisition source of the cache data has been described. In the present embodiment, a method will be described in which the source AP acquisition source determination unit 2 determines the acquisition source of cache data. In the present embodiment, the functional configuration and hardware configuration of the AP are the same as those in the first embodiment.

  FIG. 13 is a flowchart showing an example of the operation of the AP at the time of executing handover in the present embodiment. When the original AP receives a handover start request from the terminal, the handover process is started. Following this handover process, the following migration process is started.

  When the migration process starts, first, the cache information notifying unit 5 of the original AP reads the cache information list from the storage unit 4, and notifies the acquisition source determining unit 2 of the original AP of the read cache information list (step) S46). At this time, the cache information notification unit 5 of the original AP may notify the acquisition source determination unit 2 of the entire cache information list, or selectively acquires a part of the cache information list related to the terminal. Part 2 may be notified.

  When the cache information list is notified, the acquisition source determination unit 2 of the original AP selects one cache information from the notified cache information list (step S47). The acquisition source determination unit 2 may select the cache information at random or may select the cache information in the order arranged in the cache information list.

  Next, the acquisition source determination unit 2 determines the acquisition source of the cache data corresponding to the selected cache information from other communication nodes (step S48). Specifically, the acquisition source determination unit 2 determines whether to acquire cache data from the original AP or from a server that stores the cache data. At this time, the acquisition source determination unit 2 determines the acquisition source based on the cache information so that the acquisition time of the cache data is shortened. That is, the acquisition source determination unit 2 determines a communication node (original AP or server) that can acquire cache data at high speed as an acquisition source.

  Note that the acquisition source determination method is as described above. However, in the present embodiment, the acquisition source determination unit 2 of the original AP determines the acquisition source based on the cache information and the history information of the own device stored in the storage unit 4 of the original AP. As described in the second embodiment, the acquisition source determination unit 2 may determine an acquisition source using an available bandwidth.

  When the acquisition source determination unit 2 determines the acquisition source of the cache data, the acquisition source determination unit 2 updates the acquisition source list (step S49). The acquisition source list is as described above. Each time the acquisition source determination unit 2 determines the acquisition source of one cache data, the acquisition source determination unit 2 adds the corresponding acquisition source information to the acquisition source list and updates the acquisition source list.

  After updating the acquisition source list, the acquisition source determination unit 2 determines whether the acquisition source of all cache data corresponding to the cache information list has been determined (step S50). If there is cache data whose acquisition source has not been determined (NO in step S50), the acquisition source determination unit 2 selects the next cache information (step S47). On the other hand, when the acquisition source of all the cache data is determined (YES in step S50), the acquisition source determination unit 2 notifies the acquisition source list to the data acquisition unit 1 of the destination AP specified by the start request (step S51). ).

  The data acquisition unit 1 of the destination AP notified of the acquisition source list transmits a data request according to the notified acquisition source list, and acquires each cache data from each acquisition source (step S52). The method for acquiring cache data from each acquisition source is as described above.

  The data acquisition unit 1 of the previous AP writes the cache data acquired in this way to the storage unit 4 (step S53). As a result, the cache data corresponding to the cache information list of the original AP is cached in the storage unit 4 of the previous AP. When the writing of the cache data is completed, the acquisition source determination unit 2 of the previous AP updates the cache information list and history information of the own device stored in the storage unit 4 (step S54).

  Through the above processing, the cache data of the original AP can be migrated to the destination AP. Further, the acquisition source determination unit 2 of the original AP can determine the acquisition source of each cache data.

  In the present embodiment, the destination AP does not have to acquire cache data cached by its own device from other communication nodes. Such processing can be realized by the same method as in step S2.

  If the actual throughput when the data acquisition unit 1 of the destination AP acquires cache data from the server is slower than the throughput of the cache information, the data acquisition unit 1 changes the acquisition source from the server to the original AP. May be.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. Further, for example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

1: data acquisition unit, 2: acquisition source determination unit, 3: cache transmission unit, 4: storage unit, 5: cache information notification unit, 6: interface unit, 100: computer, 101: processor, 102: input device, 103 : Display device, 104: Communication device, 105: Storage device

Claims (8)

  A communication apparatus comprising: a data acquisition unit that acquires cache data stored in a handover source of a wireless communication apparatus from an acquisition source determined based on cache information including an identifier of the cache data. The communication apparatus according to claim 1, wherein the acquisition source is the handover source or a server storing the cache data. The cache information includes at least one of a throughput when the handover source acquires the cache data, a round trip time, an acquisition date and time, a time required for acquisition, and a data size of the cache data. The communication apparatus according to claim 2. The communication apparatus according to any one of claims 1 to 3, further comprising an acquisition source determination unit that determines the acquisition source based on the cache information notified from the handover source. The communication apparatus according to claim 4, wherein the acquisition source determination unit determines the acquisition source based on a vacant bandwidth between the handover source notified from the handover source. The communication apparatus according to claim 1, wherein the acquisition source is notified from the handover source. The communication device according to any one of claims 1 to 6,
The handover source;
The wireless communication device;
A communication system including:   A communication program for causing a computer to execute a step of acquiring cache data stored in a handover source of a wireless communication apparatus from an acquisition source determined based on cache information including an identifier of the cache data.

Images