Communication device, communication system, and communication method

A communication device, including: a processor configured to estimate each of a plurality of first throughputs for each of a plurality of first route patterns corresponding to each of combinations of a plurality of first routes used in parallel, coupling the communication device to a first content server, estimate each of a plurality of second throughputs for each of a plurality of second route patterns corresponding to each of combinations of a plurality of second routes used in parallel, coupling the communication device to a second content server, select one of the plurality of the first and second route patterns based on the estimated plurality of the first and second throughputs, acquire an identical content from the first content server or the second content server using the selected one of the plurality of the first and second route patterns, and transmit the acquired identical content to a terminal device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-058797, filed on Mar. 21, 2013, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a communication device, a communication system, and a communication method for selecting a content server in the communication device.

BACKGROUND

Currently, a wireless communication system such as a portable telephone system and a wireless local area network (LAN) has been widely used. Further, a next-generation communication technique has been continuously discussed so as to further improve a communication speed and communication capacity in a mobile communication field. For example, in 3rd generation partnership project (3GPP) which is a standard-setting organization, standardization of a communication standard such as long term evolution (LTE) and LTE-advance (LTE-A) based on the LTE has been completed or examined.

In such wireless communication system, there is a case in which wireless communication in which a micro base station (or femtocell base station; femto BS. The micro base station may be referred to below as a femtocell base station) is used is performed.

A femtocell base station is capable of performing wireless communication with a registered user (or a registered terminal device) and has difficulty in wireless communication with users other than the registered user, for example. Femtocell base stations are installed in indoor or underground places in which communication radio waves are weaker than those in outdoor places, for example, and are capable of performing wireless communication with terminal devices in such places as well. Femtocell base stations employing the LTE communication standard have been started to be sold today.

In a case in which a femtocell base station is installed in a house or the like, the femtocell base station is coupled to a network of a mobile communication network provider which provides the femtocell base station, for example. The femtocell base station is capable of accessing a content server and the like, for example, by using the network of the mobile communication network provider so as to provide contents to subordinate terminals.

Further, in a case in which a femtocell base station is installed in a house or the like, the femtocell base station (or a home network including terminals) is coupled to a network of a provider which provides a connection service to Internet, for example. The femtocell base station is also capable of accessing a content server by using the network of the provider, for example.

Thus, the femtocell base station is coupled to a network of a mobile communication network provider and a network of a provider, for example, and is capable of accessing a content server and the like by using a plurality of routes. Which provider's network or which route the femtocell base station uses is determined in accordance with a destination internet protocol (IP) address of a transmission packet, for example. When a transmission destination IP address of an IP packet is address #1, for example, the femtocell base station selects route #1 and transmits the IP packet to a network of a provider. On the other hand, when a transmission destination IP address of an IP packet is address #2, for example, the femtocell base station selects route #2 and transmits the IP packet to a network of a mobile communication network provider.

Meanwhile, examples of a network for delivering contents such as a moving image and music via Internet include a contents delivery network.

A plurality of content servers are coupled to the contents delivery network and hold contents identical to each other, and the contents are delivered from a content server which is closest to a user, for example. Selection of a content server in the contents delivery network is performed in accordance with an IP address of a domain name server (DNS), for example. The DNS server is a server which replies an IP address corresponding to a uniform resource locator (URL) in response to a DNS query including the URL, for example.

For example, when a DNS server in the contents delivery network receives a DNS query from a DNS server of a certain network, the DNS server in the contents delivery network replies an IP address of content server #1, and when the DNS server in the contents delivery network receives a DNS query from a DNS server of another network, the DNS server in the contents delivery network replies an IP address of content server #2.

Meanwhile, there is a technique called link aggregation in a communication field. The link aggregation is a technique for performing communication by using one or a plurality of routes simultaneously, for example. A wider bandwidth is realized by the link aggregation, for example, being able to improve a throughput (or transmission capacity) of traffic flow.

The technique related to the link aggregation includes the following example. Namely, there is such technique that a communication terminal refers to a connection rule table including a priority order and communication fee for every access point, selects an access point to be coupled from a usable network, and establishes link aggregation so as to perform communication.

Japanese Laid-open Patent Publication No. 2009-246875 is an example of related art.

SUMMARY

According to an aspect of the invention, a communication device, includes a first communication interface configured to communicate with a first content server or a second content server, the first content server and the second content server being configured to deliver an identical content, a second communication interface configured to communicate with a terminal device, and a processor configured to estimate each of a plurality of first throughputs for each of a plurality of first route patterns, each of a plurality of first route patterns corresponding to each of combinations of a plurality of first routes used in parallel, the plurality of the first routes coupling the communication device to the first content server respectively, estimate each of a plurality of second throughputs for each of a plurality of second route patterns, each of a plurality of second route patterns corresponding to each of combinations of a plurality of second routes used in parallel, the plurality of the second routes coupling the communication device to the second content server respectively, select one of the plurality of the first and second route patterns based on the estimated plurality of the first and second throughputs, acquire the identical content from the first content server or the second content server using the selected one of the plurality of the first and second route patterns, and transmit the acquired identical content to the terminal device.

DESCRIPTION OF EMBODIMENTS

However, a femtocell base station determines which route the femtocell base station uses among a plurality of routes in accordance with a destination IP address of a transmission packet, for example, as described above. Therefore, when the femtocell base station performs communication with any content server by using the link aggregation, the femtocell base station has difficulty in selection of a content server which is coupled with the femtocell base station by a pattern of the link aggregation which exhibits a high throughput. That is, when the femtocell base station performs communication with any content server among a plurality of content servers by using the link aggregation, the femtocell base station has difficulty in selection of a content server in which a higher throughput is obtained compared to other content servers.

Further, an end-to-end throughput between a content server and a terminal is determined depending not only on a throughput in a wired zone between the content server and a femtocell base station but also on a throughput in a wireless zone between the femtocell base station and a terminal. Accordingly, even in a case of a pattern of the link aggregation of which a throughput in the wired zone is higher than that of other patterns, an end-to-end throughput may not become higher when a throughput in a wireless zone is lower than that in a wired zone.

Meanwhile, the femtocell base station selects a route in accordance with a destination IP address, for example. Therefore, it is difficult for the femtocell base station to select a content server which is coupled by a pattern exhibiting a low processing load of the base station among a plurality of link aggregation patterns in a wired zone in which a throughput equivalent to that in a wireless zone is obtained.

Further, the technique in which a communication terminal selects an access point by using a connection rule table is a technique in which the communication terminal selects an access point in the light of a priority order and communication fee of each access point, for example. Accordingly, a content server which is coupled by a pattern of the ling aggregation which exhibits a higher throughput than other patterns is not selected among a plurality of content servers, in this technique either.

Therefore, it is desirable to provide a communication device, a communication network system, and a method for selecting a content server that enable selection of a content server from which a higher throughput is obtained than other content servers in a case in which communication is performed by using link aggregation.

Further, it is desirable to provide a communication device, a communication network system, and a method for selecting a content server that enable that enable selection of a content server coupled by a pattern exhibiting a low processing load among patterns of link aggregation in which a throughput equivalent to a throughput in wireless communication is obtained.

Furthermore, it is desirable to provide a communication device, a communication network system, and a method for selecting a content server that realize improvement of a throughput between a content server and a terminal device.

Embodiments of the present disclosure are described below.

First Embodiment

A first embodiment is first described.FIG. 1illustrates a configuration example of a communication network system10according to the first embodiment.

The communication network system10includes first and second content servers400-2and400-3, a communication device100, and a terminal device500.

The first and second content servers400-2and400-3are capable of delivering identical contents. The first and second content servers400-2and400-3accumulate video data and audio data related to contents in a file format, for example.

The communication device100acquires a content from the first or second content server400-2or400-3and transmits the acquired content to the terminal device500. The communication device100includes a content server selection unit160and a content transfer unit161.

As illustrated inFIG. 1, here are a plurality of routes from the communication device100to the first content server400-2. There are also a plurality of routes from the communication device100to the second content server400-3.

Further, there are a plurality of route patterns which are identified by one route or a plurality of routes which are simultaneously used, as a plurality of routes from the communication device100to the first content server400-2. There is also a plurality of route patterns which are identified by one route or a plurality of routes which are simultaneously used, as a plurality of routes from the communication device100to the second content server400-3. A route pattern is a pattern with respect to one or a plurality of routes which constitute link aggregation, for example. The communication device100uses one or a plurality of routes which are simultaneously used so as to acquire a content from the first or second content server400-2or400-3by the technique of the link aggregation, for example.

The content server selection unit160selects the first or second content server400-2or400-3which is coupled with the communication device100by a route pattern of which a throughput is estimated to be highest among these route patterns.

The content transfer unit161acquires a content from the first or second content server400-2or400-3which is selected and transmits the acquired content to the terminal device500.

Thus, in the first embodiment, the communication device100is capable of selecting the content server400-2or400-3which is coupled by a pattern of the link aggregation which exhibits a higher throughput than other patterns, between a plurality of content servers400-2and400-3.

Further, the communication device100selects such content server400-2or400-3so as to use a route pattern exhibiting a high throughput. Thus, the communication device100is capable of improving a throughput between the content server400-2and the terminal device500and between the content server400-3and the terminal device500, for example.

The communication device100is a base station device, for example. In this case, the communication device100is capable of performing wireless communication with the terminal device500and transmitting a content acquired from the first or second content server400-2or400-3to the terminal device500by wireless communication.

In this case, the communication device100measures a throughput of wireless communication between the communication device100and the terminal device500so as to select a route pattern using the smallest number of routes among route patterns of which throughputs are estimated to be higher than the measurement result. Then, the communication device100selects the first or second content server400-2or400-3which is coupled with the communication device100by a route pattern of which a throughput is estimated to be highest among these route patterns.

The communication device100selects a route pattern using the smallest number of routes among the route patterns of which throughputs are estimated to be higher than a throughput of wireless communication, so that the communication device100is capable of selecting a route pattern exhibiting a low processing load in the communication device100.

Further, the communication device100selects a route pattern of which a throughput is estimated to be highest among such route patterns. Therefore, the communication device100is capable of selecting the first or second content server400-2or400-3which is coupled by a pattern exhibiting a lower processing load, among patterns of the link aggregation in which a throughput equivalent to a throughput of wireless communication is obtained.

Second Embodiment

A second embodiment is now described. A configuration example of a communication network system according to the second embodiment is first described.

<Configuration Example of Communication Network System10>

FIG. 2illustrates a configuration example of a communication network system10according to the second embodiment.

The communication network system10includes a contents delivery network (may be referred to below as a CDN)400for delivering contents. Content servers400-2and400-3are coupled to the CDN400and contents are delivered from the content servers400-2and400-3. Types of contents include moving images, music, and games, for example. Video data and audio data related to these contents are stored in the content servers400-2and400-3in a file format.

As illustrated inFIG. 2, the communication network system10includes a femtocell base station device (may be referred to below as a femtocell base station)100, an internet service provider (ISP)200, an evolved packet core (EPC)300, the CDN400, and a terminal device (may be referred to below as a terminal)500. Here, the femtocell base station100and the terminal500constitute a home network, for example.

The femtocell base station100is a communication device, for example. The femtocell base station100performs wireless communication with the terminal500and also performs communication with the content servers400-2and400-3via the ISP200and the like. The femtocell base station100provides a service such as delivery of contents to a registered user (or registered terminal500) but the femtocell base station100does not provide a service to a user other than the registered user. Details of the femtocell base station100will be described later.

The ISP200is a network of a provider which provides a service for coupling a home network to Internet, for example. To the ISP200, a DNS-ISP200-1is coupled.

The DNS-ISP200-1is a DNS server which is coupled to the ISP200, for example. When the DNS-ISP200-1receives a DNS query which is transmitted from the femtocell base station100, the DNS-ISP200-1transmits the DNS query to a DNS-CDN400-1. When the DNS-ISP200-1receives a DNS reply with respect to the DNS query from the DNS-CDN400-1, the DNS-ISP200-1transmits the DNS reply to the femtocell base station100. The DNS-ISP200-1receives the DNS reply with respect to the DNS query so as to acquire an IP address of the content server400-2or400-3corresponding to a URL.

The EPC300is a network of a mobile communication network provider which provides the femtocell base station100, for example. A tunnel based on an IP security tunnel protocol is set between the EPC300and the femtocell base station100. For example, a security GW is coupled to the EPC300and the security GW and the femtocell base station100perform processing such as capsulation of an IP packet and termination of the capsulated IP packet.

Further, a DNS-EPC300-1is coupled to the EPC300as a DNS server.

When the DNS-EPC300-1receives a DNS query which is transmitted from the femtocell base station100, the DNS-EPC300-1transmits the DNS query to the DNS-CDN400-1. When the DNS-EPC300-1receives a DNS reply with respect to the DNS query from the DNS-CDN400-1, the DNS-EPC300-1transmits the DNS reply to the femtocell base station100. The DNS-EPC300-1receives the DNS reply with respect to the DNS query so as to acquire an IP address of the content server400-2or400-3corresponding to a URL.

The CDN400is a network of a content delivery provider, for example. To the CDN400, the DNS-CDN400-1and the content servers400-2and400-3are coupled.

The DNS-CDN400-1is a DNS server in the CDN400, for example. The DNS-CDN400-1receives a DNS query which is transmitted from the DNS-ISP200-1and the DNS-EPC300-1and replies an IP address of one of the content servers400-2and400-3. The DNS-CDN400-1replies an IP address of the content server400-2or400-3which is closer to a user and usually replies an IP address of one of the content servers400-2and400-3in accordance with a DNS server which transmits the DNS query.

For example, the DNS-CDN400-1replies an IP address of the content server400-2with respect to a DNS query which is transmitted from the DNS-ISP200-1. Further, the DNS-CDN400-1replies an IP address of the content server400-3with respect to a DNS query which is transmitted from the DNS-EPC300-1.

Both of the content servers400-2and400-3store identical contents and both of the content servers400-2and400-3are capable of delivering contents. The content servers400-2and400-3include a large-capacity memory such as a hard disk drive, for example, and stores contents in the memory.

The terminal500is a communication device such as a feature phone and a smart phone. The terminal500includes an LTE interface540and performs wireless communication based on a communication standard of the LTE. Here, the terminal500is registered as a wirelessly-communicable terminal in the femtocell base station100and the terminal500is capable of accessing the femtocell base station100in a communicable range (or a cell range) of the femtocell base station100so as to receive a service of delivery of contents and the like.

In the network configuration example illustrated inFIG. 2, there are a plurality of routes from the femtocell base station100to the content servers400-2and400-3. For example, routes to the content server400-2include IP route #1 which goes through the ISP200and IP route #2-b which goes through the ISP200and the EPC300. Further, routes to the content server400-3include IP route #1-b which goes through the ISP200and IP route #2 which goes through the ISP200and the EPC300.

The content server400-2is capable of transmitting identical contents by using both of the IP route #1 and the IP route #2-b with the technique of the link aggregation, for example. Further, the content server400-3is capable of transmitting identical contents by using both of the IP route #2 and the IP route #1-b with the technique of the link aggregation.

Alternatively, the content server400-2is capable of transmitting contents by using the IP route #1 or the IP route #2-b with the technique of the link aggregation. Further, the content server400-3is also capable of transmitting contents by using the IP route #2 or the IP route #1-b with the technique of the link aggregation.

The link aggregation represents a technique for performing communication by using one or a plurality of routes (or lines), for example. Further, a pattern (or a route pattern) of the link aggregation represents a combination with respect to one or a plurality of IP routes which constitute the link aggregation, for example. There are three patterns which are the IP route #1+the IP route #2-b, the IP route #1, and the IP route #2-b as patterns of the link aggregation in the content server400-2, for example.

A configuration example of the femtocell base station100is now described. As illustrated inFIG. 2, the femtocell base station100includes a content server information acquisition unit122, a first measurement unit123, a content server selection unit124, a content transfer unit125, an LTE interface130, an Ethernet® interface (“Ether” inFIG. 2)150, and a network address translation unit (NAT)151.

Here, the content server selection unit124corresponds to the content server selection unit160in the first embodiment, for example. Further, the content transfer unit125corresponds to the content transfer unit161in the first embodiment, for example.

The content server information acquisition unit122transmits a DNS query to the DNS-ISP200-1and the DNS-EPC300-1and receives a DNS reply from the DNS-ISP200-1and the DNS-EPC300-1. The content server information acquisition unit122receives a DNS reply so as to acquire IP addresses of the content servers400-2and400-3which correspond to a URL which is inquired by the DNS query. The content server information acquisition unit122outputs the acquired IP addresses of the content servers400-2and400-3to the first measurement unit123.

The first measurement unit123measures delay time or a throughput related to an IP route leading to the content servers400-2and400-3on the basis of the IP addresses which are acquired by the content server information acquisition unit122. Details of the measurement method will be described later.

The content server selection unit124selects the content server400-2or400-3which is coupled with the femtocell base station100by a pattern of which a throughput is estimated to be highest among patterns of the link aggregation which are identified by one IP route or a combination of a plurality of IP routes, on the basis of the measurement result of the first measurement unit123. Details of the selection method will be described later. The content server selection unit124outputs the selection result to the content transfer unit125.

The content transfer unit125acquires a content from the selected content server400-2or400-3by using the selected pattern of the link aggregation.

The acquisition of a content is performed as described below, for example. Namely, the content transfer unit125transmits a content acquisition request to the selected content server400-2or400-3by an IP route of the selected pattern of the link aggregation. The content server400-2or400-3transmits a content to a transmission source which has transmitted the content acquisition request (for example, the femtocell base station100), in response to the content acquisition request. Accordingly, the content transfer unit125is capable of acquiring a content from the selected content server400-2or400-3by using the selected pattern of the link aggregation.

Here, the content transfer unit125and the like hold an IP address belonging to the ISP200and an IP address belonging to the EPC300, for example. Accordingly, the femtocell base station100is capable of transmitting a content acquisition request to the ISP200and is capable of transmitting a content acquisition request to the EPC300by passing through the ISP200, for example.

Further, the content transfer unit125has a hyper text transfer protocol (HTTP) proxy function. The content transfer unit125acquires contents from the content servers400-2and400-3by using a communication protocol based on the HTTP. On the other hand, the terminal500has a HTTP client function, and the content transfer unit125transmits contents acquired by using the HTTP to the terminal500.

The LTE interface130is an interface for performing wireless communication based on the LTE with the terminal500, for example. For example, the LTE interface130receives a content which is outputted from the content transfer unit125and performs error correction coding processing, modulation processing, frequency conversion processing, and the like to convert the content into a wireless signal and transmit the wireless signal to the terminal500. Further, the LTE interface130receives a wireless signal which is transmitted from the terminal500and performs frequency conversion processing, demodulation processing, error correction decoding processing, and the like so as to extract data and the like and output the data and the like to the content transfer unit125. The LTE interface130may include an error correction coding circuit, a modulation circuit, an analogue to digital (A/D) circuit, and the like so as to perform such error correction coding processing, modulation processing, and the like.

The Ethernet® interface150serves as an interface between the femtocell base station100and the ISP200, for example. For example, the Ethernet® interface150receives data and the like which are outputted from the first measurement unit123and the like and generates an IP packet, in which the data is included in a payload region, so as to transmit the IP packet to the ISP200. Further, the Ethernet® interface150receives an IP packet which is transmitted from the ISP200and extracts data and the like from the payload region so as to output the data and the like to the first measurement unit123and the like, for example.

The NAT151converts an IP address for the EPC300which is included in the IP packet into an IP address for the ISP200so as to output the converted IP address to the Ethernet® interface150. For example, when an IP address for the EPC300is assigned to the LTE interface540of the terminal500and the femtocell base station100uses the IP route #1 and the IP route #1-b, the NAT151converts the IP address for the EPC300into an IP address for the ISP200. The Ethernet® interface150receives notification of the converted IP address and transmits an IP packet to the ISP200.

The terminal500includes the LTE interface540. The LTE interface540is an interface for performing wireless communication based on the LTE with, for example, the femtocell base station100. For example, the LTE interface540converts data and the like into a wireless signal to transmit the wireless signal to the femtocell base station100or receives a wireless signal which is transmitted from the femtocell base station100to extract data and the like from the wireless signal. The LTE interface540may include an error correction coding circuit, a modulation circuit, a frequency conversion circuit, and the like so as to perform such conversion.

Further, the terminal500has the HTTP client function and acquires contents from the content servers400-2and400-3via the HTTP proxy of the content transfer unit125by the HTTP.

FIG. 3illustrates a configuration example of hardware of the femtocell base station100. The femtocell base station100includes a central processing unit (CPU)110, a memory120, the LTE interface130, and the Ethernet® interface150and the CPU110, the memory120, the LTE interface130, and the Ethernet® interface150are mutually coupled via a bus145.

A program121is stored in the memory120. The CPU110reads and executes the program121so as to realize respective functions of the content server information acquisition unit122, the first measurement unit123, the content server selection unit124, and the content transfer unit125. Accordingly, the content server information acquisition unit122, the first measurement unit123, the content server selection unit124, and the content transfer unit125correspond to the CPU110, for example.

<Configuration Examples of Other Devices>

Configuration examples of a DNS server of the DNS-ISP200-1and the like, the content servers400-2and400-3, and the terminal500are now described.

FIG. 4illustrates a configuration example of hardware of the DNS-ISP200-1. Here, respective configurations of the DNS-ISP200-1, the DNS-EPC300-1, and the DNS-CDN400-1are identical to each other, so that description given here is related to the DNS-ISP200-1unless any notification is especially provided.

The DNS-ISP200-1includes a CPU210, a memory220, and an Ethernet® interface240and the CPU210, the memory220, and the Ethernet® interface240are mutually coupled via a bus245. A program221is stored in the memory220. The CPU210reads and executes the program221so as to realize a function of a DNS message processing unit222. The DNS message processing unit222corresponds to the CPU210, for example.

The DNS message processing unit222of the DNS-ISP200-1and the DNS-EPC300-1receives a DNS query which is transmitted from the femtocell base station100via the Ethernet® interface240. Then, the DNS message processing unit222of the DNS-ISP200-1and the DNS-EPC300-1transmits the received DNS query to the DNS-CDN400-1via the Ethernet® interface240.

Further, the DNS message processing unit222of the DNS-ISP200-1and the DNS-EPC300-1receives a DNS reply which is transmitted from the DNS-CDN400-1via the Ethernet® interface240. Then, the DNS message processing unit222of the DNS-ISP200-1and the DNS-EPC300-1transfers the DNS reply to a device of a transmission source which has transmitted the DNS query (for example, the femtocell base station100) via the Ethernet® interface240.

On the other hand, the DNS message processing unit222of the DNS-CDN400-1receives a DNS query via the Ethernet® interface240. Then, the DNS message processing unit222of the DNS-CDN400-1replies an IP address of the optimum content server400-2or400-3in accordance with a network to which a DNS server which has transmitted the DNS query belongs. For example, the DNS message processing unit222of the DNS-CDN400-1replies an IP address of the content server400-2in response to a DNS query which is transmitted from the DNS-ISP200-1. Further, the DNS message processing unit222replies an IP address of the content server400-3in response to a DNS query which is transmitted from the DNS-EPC300-1. The DNS-CDN400-1transmits a reply as a DNS reply in reply of an IP address.

FIG. 5illustrates a configuration example of hardware of the content servers400-2and400-3. The content servers400-2and400-3have the same configuration as each other, so that the content server400-2is described as an example.

The content server400-2includes a CPU410, a memory420, a hard disk drive430, and an Ethernet® interface440and the CPU410, the memory420, the hard disk drive430, and the Ethernet® interface440are mutually coupled via a bus445.

A program421is stored in the memory420. The CPU410reads and executes the program421so as to realize a function of a content transmission unit422. The content transmission unit422corresponds to the CPU410, for example.

The content transmission unit422reads a content file431which is stored in the hard disk drive430and transmits a content by using an IP route via the Ethernet® interface440. For example, when the content transmission unit422receives a content request, the content transmission unit422transmits a content to a transmission source of the content request.

FIG. 6illustrates a configuration example of hardware of the terminal500. The terminal500includes a CPU510, a memory520, and an LTE interface540and the CPU510, the memory520, and the LTE interface540are mutually coupled via a bus545.

A program521is stored in the memory520. The CPU510reads and executes the program521so as to realize a function of a content processing unit522. The content processing unit522corresponds to the CPU510, for example.

The content processing unit522has the HTTP client function, for example, and receives contents which are delivered from the content servers400-2and400-3, by using the HTTP client function. Further, the content processing unit522performs compression-expansion processing with respect to received contents, for example, so as to allow a monitor screen to display a moving image related to the contents and allow a microphone to output sounds.

An operation example in the second embodiment is now described.FIG. 7illustrates a sequence example in the communication network system10, andFIG. 8illustrates an example of a flowchart related to content server selection processing.

As illustrated inFIG. 7, the terminal500transmits a HTTP acquisition message to the femtocell base station100(S10). The HTTP acquisition message includes URLs of the content servers400-2and400-3. The terminal500transmits the HTTP acquisition message so as to request delivery of contents, for example.

When the content transfer unit125of the femtocell base station100receives the HTTP acquisition message, the content transfer unit125extracts the URLs from the HTTP acquisition message and outputs the URLs to the content server selection unit124(S11).

Subsequently, the content server selection unit124searches a cache table which is held by the content server selection unit124, so as to confirm whether or not selection results of the contents servers400-2and400-3corresponding to the received URLs are stored (S12). Details of the cache table will be described later.

When the selection results corresponding to the URLs are stored in the cache table (Yes in S12), the content server selection unit124selects one content server400-2or400-3by using the selection results (S26).

On the other hand, when the selection results corresponding to the URLs are not stored in the cache table (No in S12), the content server selection unit124outputs the URLs to the content server information acquisition unit122(S13).

Subsequently, the content server information acquisition unit122transmits a DNS query to a DNS server of a network to which the femtocell base station100is coupled (S14, S18). In the example ofFIG. 7, the content server information acquisition unit122transmits a DNS query to the DNS-ISP200-1and the DNS-EPC300-1.

When the DNS-ISP200-1receives the DNS query, the DNS-ISP200-1transmits the received DNS query to the DNS-CDN400-1which is a higher-order DNS server (S15).

When the DNS-CDN400-1receives the DNS query, the DNS-CDN400-1transmits an IP address of the content server400-2(content server #1_IP) as a DNS reply to the DNS-ISP200-1which is a transmission source which has transmitted the DNS query (S16).

When the DNS-ISP200-1receives the DNS reply, the DNS-ISP200-1transmits the DNS reply to the femtocell base station100which has transmitted the DNS query (S17). The content server information acquisition unit122receives the DNS reply and acquires an IP address of the content server400-2corresponding to the URL, for example.

Further, when the DNS-EPC300-1receives the DNS query, the DNS-EPC300-1transmits the received DNS query to the DNS-CDN400-1which is a higher-order server (S19).

When the DNS-CDN400-1receives the DNS query, the DNS-CDN400-1transmits an IP address of the content server400-3(content server #2_IP) as a DNS reply to the DNS-EPC300-1which is a transmission source which has transmitted the DNS query (S20).

When the DNS-EPC300-1receives the DNS reply, the DNS-EPC300-1transmits the DNS reply to the femtocell base station100which has transmitted the DNS query (S21). The content server information acquisition unit122receives the DNS reply and acquires an IP address of the content server400-3corresponding to the URL, for example.

Subsequently, the content server information acquisition unit122outputs the acquired IP addresses of the content servers400-2and400-3to the first measurement unit123(S22).

Then, the first measurement unit123measures delay time or a throughput related to an IP route leading to the content server400-2(S23). Further, the first measurement unit123measures delay time or a throughput related to an IP route leading to the content server400-3(S24). Details of the measurement method of delay time and a throughput will be described later.

Subsequently, the first measurement unit123outputs a measurement result to the content server selection unit124(S25).

Then, the content server selection unit124selects the content server400-2or400-3which is coupled to the femtocell base station100by a pattern of the link aggregation in which it is estimated that the highest throughput is obtained, on the basis of the measurement result of the first measurement unit123(S26). Details of the selection method will be described later.

Hereinafter, description is given on the assumption that the content server400-2which is coupled by a pattern of the link aggregation in which the IP route #1 and the IP route #2-b (for example,FIG. 2) are simultaneously used is selected.

Subsequently, the content server selection unit124outputs the selection result to the content transfer unit125(S27).

Then, the content transfer unit125acquires a content from the content server400-2which is coupled by the pattern by using the pattern of the link aggregation in which the IP route #1 and the IP route #2-b are simultaneously used (S30, S31).

For example, image data and audio data in the content are stored in the content server400-2in a file format, and the content server400-2transmits data stored in a certain region in the file (from the 1st byte to the 100th byte, for example) via the IP route #1 and transmits data stored in another region in the same file (from the 101st byte to the 200th byte, for example) via the IP route #2-b simultaneously. In this case, the content transfer unit125combines data, which are received via the two routes, in the content (combines from the 1st byte to the 200th byte, for example) so as to obtain a single content.

Alternatively, the content server400-2may sort data stored in a certain region in the file to IP packet #1 and data stored in another region in the same file to IP packet #2 so as to transmit the IP packets #1 and #2 to the IP routes #1 and #2-b respectively.

Subsequently, the content transfer unit125transmits the acquired content to the terminal500as a HTTP reply (S32). For example, the content transfer unit125transmits certain number of bytes, such as several bytes from the head of a content acquired from the content server400-2, to the terminal500in sequence.

FIG. 8is a flowchart illustrating an example of content server selection processing, andFIG. 9illustrates an example of a cache table. Details of a cache table, the measurement method performed by the first measurement unit123, details of content server selection performed by the content server selection unit124, and the like are described below with reference toFIGS. 8 and 9.

First, when the femtocell base station100starts processing (S40), the content server selection unit124receives a URL from the content transfer unit125(S41).

Then, the content server selection unit124confirms whether or not a selection result of the content server400-2or400-3corresponding to the received URL is cached in a cache table1241(S42).

FIG. 9illustrates an example of the cache table1241. The cache table1241is a table which is held by the content server selection unit124, for example, and includes items which are “URL”, “IP address of selected content server”, and “constituent IP route”.

In the item of “URL”, part of a URL which is transmitted by the terminal500is stored. For example, when the terminal500transmits “http://www.aaa.com/aaa1/aaa2.html”, “www.aaa.com” which is part of “http://www.aaa.com/aaa1/aaa2.html” is stored. When the terminal500transmits “http://www.aaa.com/aaa3/aaa4.html” in the next time, the content server selection unit124determines that “http://www.aaa.com/aaa3/aaa4.html” is cached because “www.aaa.com” is duplicated. A range to be stored in a region of “URL” may be determined by setting of the femtocell base station100, for example.

In the item of “IP address of selected content server”, IP addresses of the content servers400-2and400-3which have been selected thus far by the content server selection unit124are stored with respect to the URL. The example ofFIG. 9illustrates that the content server400-2(or the content server400-3) having an IP address of “192.168.10.1” is selected with respect to “www.aaa.com”.

In the item of “constituent IP route”, IP routes which are used when the femtocell base station100acquires contents from the content servers400-2and400-3are stored. In the example ofFIG. 9, “via ISP+via EPC” is stored, which represents that an IP route going through the ISP200(the IP route #1, for example) and an IP route going through the EPC300(the IP route #2-b, for example) are used. Further, in the example ofFIG. 9, “via ISP” is stored, which represents that a route going through the ISP200(the route #1, for example) is used.

Referring back toFIG. 8, when a “URL” corresponding to the received URL is stored in the cache table1241(Yes in S42), the content server selection unit124selects the content server400-2or400-3which is stored in the cache table1241(S48). For example, the content server selection unit124acquires IP addresses of the content servers400-2and400-3from “IP address of selected content server” corresponding to the URL so as to select the content server400-2or400-3.

Thus, the femtocell base station100uses selection results (for example, IP addresses of the content servers400-2and400-3and constituent IP routes) which are stored in the cache table1241(S42), being able to perform processing at higher speed than a case in which selection results are not used.

On the other hand, when a corresponding “URL” is not stored in the cache table1241(No in S42), the content server selection unit124outputs the URL to the content server information acquisition unit122. Then, the content server information acquisition unit122transmits a DNS query to the DNS server so as to acquire IP addresses of the content servers400-2and400-3(S43). The content server information acquisition unit122outputs the acquired IP addresses to the first measurement unit123.

Subsequently, the first measurement unit123determines the number of constituent IP routes based on a setting value (S44). The number of constituent IP routes represents the number of IP routes which constitute a pattern of the link aggregation. In a case of a pattern using the IP route #1 and the IP route #2-b as a pattern of the link aggregation, the number of constituent IP routes is “2”. Further, in a case of a pattern using the IP route #1, the number of constituent IP routes is “1”.

Due to the limitation of the device performance of the femtocell base station100, the number of constituent IP routes which is up to “2” may be employed due to the link aggregation, but a processing load may exceed a predetermined threshold value in a case of the number of constituent IP routes which is “3” or more. Alternatively, there is a case in which it is favorable to set the number of constituent IP routes to “1” in initial shipping of the femtocell base station100and increase the number of constituent IP routes to “2” or more in accordance with addition of functions.

Therefore, in the femtocell base station100, the maximum value of the number of constituent IP routes may be set by a setting value in the light of a processing load and addition of functions. For example, a user of the femtocell base station100operates an operation button or the like of the femtocell base station100, being able to set a setting value.

Subsequently, the first measurement unit123examines patterns of the link aggregation of which the number of constituent IP routes is equal to or lower than the determined number of constituent IP routes, so as to select the first candidate (S45). For example, in the network configuration example illustrated inFIG. 2, when the number of constituent IP routes is determined as “2”, the following patterns are selected as the first candidate. •First candidate #21: IP route #1+IP route #2-b leading to the content server400-2, •First candidate #22: IP route #2+IP route #1-b leading to the content server400-3, •First candidate #23: IP route #1 leading to the content server400-2, •First candidate #24: IP route #2-b leading to the content server400-2, •First candidate #25: IP route #2 leading to the content server400-3, •First candidate #26: IP route #1-b leading to the content server400-3

Further, when the number of constituent IP routes is “1”, the following patterns are selected as the first candidate. •First candidate #11: IP route #1 leading to the content server400-2, •First candidate #12: IP route #2-b leading to the content server400-2, •First candidate #13: IP route #2 leading to the content server400-3, •First candidate #14: IP route #1-b leading to the content server400-3

Here, the following description is given on the assumption of an example in which “2” is set as a setting value.

Subsequently, the first measurement unit123measures delay time or a throughput related to a pattern, which is the first candidate, of the link aggregation (S46). For example, measurement is performed by using delay time or a throughout in accordance with implementation of the femtocell base station100.

Here, details of a measurement example of delay time and a measurement example of a throughput are described.

<Measurement Example of Delay Time>

The first measurement unit123measures delay time of each pattern from the first candidate #21 to the first candidate #26. For example, the first measurement unit123measures delay time by using a ping command based on an internet content message protocol (ICMP) (or echo request notice (ICMP echo message)). The first measurement unit123transmits the echo request notice to the content servers400-2and400-3and receives an echo reply notice (ICMP echo reply message) with respect to the echo request notice from the content servers400-2and400-3.

The first measurement unit123obtains round trip time (RTT) from transmission of the echo request notice to reception of the echo reply notice, for example, so as to measure delay time. When the first measurement unit123measures a plurality of IP routes, the first measurement unit123measures round trip time of a plurality of IP routes in parallel (or simultaneously). The first measurement unit123measures delay time of each of patterns, from the first candidate #21 to the first candidate #26, of the link aggregation, for example. The first measurement unit123outputs the measured delay time of each of the patterns to the content server selection unit124.

Then, the content server selection unit124estimates a throughput of each pattern of the link aggregation on the basis of the measured delay time so as to select a pattern of the link aggregation of which a throughput is estimated to be highest (S47). The content server selection unit124estimates a throughput of each pattern by using the following formula.
Estimated throughput [bps]=ΣIP route{(data size of ping [bit]×2)/round trip delay [s]}  (1)

For example, in the example of the first candidate #21, estimation throughputs of respective routes are calculated by formula (1) on the basis of the round trip delay of the IP route #1 and the IP route #2-b, and a throughput obtained by summing the estimation throughputs is an estimation throughput of the first candidate #21. Further, in the example of the first candidate #23, an estimation throughput calculated by formula (1) on the basis of round trip delay of the IP route #1 is an estimation throughput of the first candidate #23.

A throughput of the first candidate #23 which uses a single IP route may be higher than that of the first candidate #21 which uses a plurality of IP routes, depending on a state of a line which is used by each IP route. For example, in a case in which a physical line which is used by two IP routes in an overlapped manner is congested, a total throughput may be lower than a throughput of a single IP route due to the simultaneous use of the physical line by two routes.

The content server selection unit124estimates throughputs respectively from the first candidate #21 to the first candidate #26 by formula (1) and selects the first candidate (or a pattern of the link aggregation) of which a throughput is estimated to be the highest. For example, the content server selection unit124selects the first candidate #21 as a pattern of the link aggregation of which a throughput is estimated to be highest.

Subsequently, the content server selection unit124selects the content server400-2or400-3which is coupled with the femtocell base station100by the selected pattern of the link aggregation (S48). The content server selection unit124selects the content server400-2based on the first candidate #21, for example.

Estimation of a throughput based on delay time is not as precise as a throughput of a case in which a content is acquired by actually using the link aggregation. This is because processing time in the content servers400-2and400-3is not reflected to measurement of delay time and the maximum value of the data size of the ping command is smaller than other commands to be largely influenced by other communication traffics, for example.

<Measurement Example of Throughput>

A measurement example of a throughput is now described. In this case, the first measurement unit123actually acquires part of contents from the content servers400-2and400-3so as to measure a throughput in the acquisition.

For example, the first measurement unit123acquires several bytes from the head of a content which is specified by the URL through each IP route of patterns of the link aggregation from the content servers400-2and400-3by using the HTTP protocol. Then, the first measurement unit123divides the number of bytes of the acquired content by time used for the acquisition so as to measure a throughput [bps]. The number of bytes to be acquired may be set on the basis of a setting value, for example.

When the first measurement unit123measures a plurality of IP routes, the first measurement unit123measures throughputs of respective IP routes of a plurality of IP routes in parallel (or simultaneously). For example, the first measurement unit123measures a throughput of the IP route #1 and collaterally measures a throughput of the IP route #2-b, and a throughput obtained by adding these throughputs to each other is a throughput of the first candidate #21. The first measurement unit123measures throughputs of respective patterns of six candidates which are from the first candidate #21 to the first candidate #26, for example, of the link aggregation. The first measurement unit123outputs the measured throughputs of respective patterns to the content server selection unit124.

Then, the content server selection unit124determines a pattern of the link aggregation in which it is estimated that the highest throughput is obtained, on the basis of the measured throughputs (S47). For example, the content server selection unit124selects the first candidate #21.

Subsequently, the content server selection unit124selects the content server400-2or400-3which is coupled by the determined pattern (S48). For example, the content server selection unit124selects the content server400-2based on the first candidate #21.

Estimation of a throughput based on delay time is not a precise as estimation of a throughput performed by acquiring contents. This is because processing time in the content servers400-2and400-3is not reflected to measurement of delay time and the maximum value of the data size of the ping command is smaller than other commands to be largely influenced by other communication traffics, for example.

On the other hand, estimation of a throughput performed by acquiring contents is more precise than estimation of a throughput performed on the basis of delay time, but measurement takes time because part of contents is actually acquired and thus the measurement imposes a load on the communication network system10. Accordingly, whether estimation of a throughput performed on the basis of delay time or estimation of a throughput performed by partial-acquisition of contents is used may be determined on the basis of an implementation policy of the femtocell base station100, for example.

When the content server selection unit124selects the content server400-2or400-3, the content server selection unit124stores the selection result in the cache table1241(S49).

Then, the femtocell base station100ends the content server selection processing (S50).

Thus, in this communication network system10, it is possible to select the content server400-2or400-3which constitutes a pattern, in which it is estimated that a higher throughput is obtained than other patterns, of the link aggregation between a plurality of content servers400-2and400-3(S26ofFIG. 7, S47and S48ofFIG. 8, for example). Accordingly, in a case in which communication is performed by using the link aggregation, for example, the femtocell base station100is capable of selecting the content server400-2or400-3from which a higher throughput is obtained than another content server. Further, in this communication network system10, it is possible to improve end-to-end throughputs between the terminal500and the content server400-2and between the terminal500and the content server400-3, for example.

Third Embodiment

A third embodiment is now described. The third embodiment illustrates an example of selection of the content server400-2or400-3based on a throughput of wireless communication and a processing load of a femtocell base station, for example.

FIG. 10illustrates a configuration example of a communication network system10according to the third embodiment,FIG. 11illustrates a configuration example of a femtocell base station100,FIGS. 12A and 12Billustrate a sequence example according to the third embodiment, andFIG. 13is a flowchart illustrating an example of selection processing of the content server400-2or400-3.

As illustrated inFIG. 10, the communication network system10further includes an access service network/connectivity service network (ASN/CSN)600. The ASN/CSN600includes two networks which are an ASN which is a network of worldwide interoperability for microwave access (WiMAX) and a CSN corresponding to a higher-order core network of the ASN. Here, WiMAX is a type of a wireless communication method and has been standardized as IEEE802.16e by the institute of electrical and electronic engineers (IEEE) on 2005.

To the ASN/CSN600, a DNS-CSN600-1is coupled. The DNS-CSN600-1is a DNS server in the ASN/CSN600. When the DNS-CSN600-1receives a DNS query from the femtocell base station100, the DNS-CSN600-1transmits the DNS query to the DNS-CDN400-1. Further, when the DNS-CSN600-1receives a DNS reply with respect to the DNS query from the DNS-CDN400-1, the DNS-CSN600-1transmits the DNS reply to a transmission source (for example, the femtocell base station100) of the DNS query. Accordingly, the DNS-CSN600-1(or the femtocell base station100) is capable of acquiring an IP address of the content server400-2or400-3which corresponds to a URL.

The femtocell base station100further includes a second measurement unit126and a WiMAX interface152.

The second measurement unit126measures a throughput of wireless communication between the femtocell base station100and the terminal500. Details of the measurement method will be described later. The second measurement unit126outputs a measurement result to the content server selection unit124. The content server selection unit124selects the content server400-2or400-3on the basis of a measurement result obtained by the first measurement unit123and the measurement result obtained by the second measurement unit126. Details of the selection method will be described later.

The WiMAX interface152generates an IP packet representing a DNS query on the basis of an instruction from the content server information acquisition unit122, for example, so as to transmit the IP packet to the DNS-CSN600-1. Further, when the WiMAX interface152receives a DNS reply from the DNS-CSN600-1, the WiMAX interface152extracts IP addresses of the content servers400-2and400-3included in the DNS reply so as to output the IP addresses to the content server information acquisition unit122.

In the third embodiment, two IP routes which are IP route #3 and IP route #3-b are further added and patterns of the link aggregation are increased along with the addition of the IP routes.

FIG. 11illustrates a configuration example of hardware of the femtocell base station100in the third embodiment. The second measurement unit126is further added to the program121and the WiMAX interface152is coupled with other blocks via the bus145. For example, the CPU110reads and executes the program121so as to realize a function performed in the second measurement unit126. The second measurement unit126corresponds to the CPU110, for example. The CPU110exchanges a signal and the like with the WiMAX interface152via the bus145so as to exchange an IP packet and the like with the ASN/CSN600which is coupled to the WiMAX interface152, for example.

An operation example in this communication system10is now described with reference toFIGS. 12A and 12B. Here, parts of processing identical to that of the second embodiment are given the same reference characters inFIGS. 12A and 12B, and points different from the second embodiment are mainly described below.

When a URL of a DNS query object is not stored in the cache table1241(No in S12), the content server information acquisition unit122transmits a DNS query to the DNS-ISP200-1, the DNS-EPC300-1, and the DNS-CSN600-1(S14, S18, S60).

When the DNS-CSN600-1receives the DNS query from the femtocell base station100, the DNS-CSN600-1transmits the DNS query to the DNS-CDN400-1(S61).

When the DNS-CDN400-1receives the DNS query which is transmitted from the DNS-CSN600-1, the DNS-CDN400-1replies an IP address of the content server400-2, for example, as a DNS reply to the DNS-CSN600-1(S62).

When the DNS-CSN600-1receives the DNS reply which is transmitted from the DNS-CDN400-1, the DNS-CSN600-1transmits the DNS reply to the femtocell base station100(S63). The content server information acquisition unit122receives the DNS reply and acquires the IP address of the content server400-2.

The content server information acquisition unit122outputs the acquired IP address of the content server400-2or400-3to the first measurement unit123(S22).

The first measurement unit123measures delay time or a throughput related to an IP route leading to the content server400-2(S23). Further, the first measurement unit123measures delay time or a throughput related to an IP route leading to the content server400-3(S24). As IP routes which are measurement objects, the IP route #3 leading to the content server400-2and the IP route #3-b leading to the content server400-3are added. The measurement is same as that of the second embodiment, for example. The first measurement unit123outputs a measurement result to the content server selection unit124.

Meanwhile, the second measurement unit126measures a throughput of wireless communication between the femtocell base station100and the terminal500(S64). Details of the measurement method will be described later. The second measurement unit126outputs a measurement result to the content server selection unit124(S65).

The content server selection unit124selects the content server400-2or400-3which is coupled with the femtocell base station100by a pattern in which it is estimated that the highest throughput is obtained among patterns of the link aggregation, on the basis of the measurement result from the first measurement unit123(S25) and the measurement result from the second measurement unit126(S65). Details of the selection method will be described later.

Here, in this operation example, description is given on the assumption that the content server selection unit124selects the content server400-2which is coupled by a pattern of the link aggregation in which the IP route #1 and the IP route #2-b are simultaneously used. The content server selection unit124transfers a selection result to the content transfer unit125(S27). The following operation is same as that of the second embodiment, so that description thereof is omitted.

FIG. 13is a flowchart illustrating an example of content server selection processing. Details of the measurement method in the first measurement unit123and the second measurement unit126, details of the content server selection processing in the content server selection unit124, and the like are described with reference toFIG. 13. Parts of processing, which is identical to that of the second embodiment (for example,FIG. 8), of the flowchart ofFIG. 13are also given the same reference characters and description thereof is arbitrarily omitted.

When the first measurement unit123receives IP addresses of the content servers400-2and400-3(S43), the first measurement unit123determines the number of constituent IP routes on the basis of a setting value which is set as a specification of the femtocell base station100, for example (S44). For example, the first measurement unit123determines “3” as the number of constituent IP routes.

Subsequently, the first measurement unit123examines patterns of the link aggregation so as to select the first candidate of a pattern of the link aggregation (S45). In the example of the network configuration ofFIG. 10, when the number of constituent IP routes is “3”, the following patters are selected as the first candidate. •First candidate #331: IP route #1+IP route #2-b+IP route #3 leading to the content server400-2, •First candidate #332: IP route #2+IP route #1-b+IP route #3-b leading to the content server400-3, •First candidate #321: IP route #1+IP route #2-b leading to the content server400-2, •First candidate #323: IP route #1+IP route #3 leading to the content server400-2, •First candidate #324: IP route #2-b+IP route #3 leading to the content server400-2, •First candidate #325: IP route #2+IP route #1-b leading to the content server400-3, •First candidate #326: IP route #2+IP route #3-b leading to the content server400-3, •First candidate #328: IP route #1-b+IP route #3-b leading to the content server400-3, •First candidate #311: IP route #1 leading to the content server400-2, •First candidate #312: IP route #2-b leading to the content server400-2, •First candidate #313: IP route #3 leading to the content server400-2, •First candidate #314: IP route #2 leading to the content server400-3, •First candidate #315: IP route #1-b leading to the content server400-3, •First candidate #316: IP route #3-b leading to the content server400-3

Subsequently, the first measurement unit123measures delay time or a throughput related to each pattern of the link aggregation of the first candidates (S46). Measurement of delay time and a throughput is performed in the same manner as that of the second embodiment. Whether delay time or a throughput is used depends on implementation of the femtocell base station100, for example.

Subsequently, the second measurement unit126measures a throughput of wireless communication between the femtocell base station100and the terminal500(S81). A throughput of wireless communication is measured as follows, for example.

Namely, the second measurement unit126may estimate a throughput on the basis of delay time as is the case with the second embodiment. Specifically, the second measurement unit126performs estimation by using formula (1), for example.

Alternatively, the second measurement unit126may actually acquire data from the terminal500to measure a throughput in the acquisition, as is the case with the second embodiment. Specifically, the second measurement unit126may acquire data (several bytes from the head, for example) from the terminal500and divide the number of bytes of the acquired data by time used for the acquisition so as to measure a throughput [bps].

Further, the second measurement unit126may measure a throughput on the basis of a modulation and coding scheme (MCS). The MCS is a combination of a modulation system of wireless communication between the femtocell base station100and the terminal500and a coding rate, for example, and is determined in assignment of a wireless resource on the basis of radio quality such as a signal to interference ratio (SIR). As a multivalued level of the modulation system is higher and further, a coding rate is higher, a throughput becomes higher. A pattern of a combination between a modulation system and a coding rate is determined as a standard specification of LTE and a pattern is determined also in a standard specification of a wireless local area network (LAN) which is different from the LTE, though. The second measurement unit126may measure a throughput in accordance with a combination between a modulation system and a coding rate which are determined in assignment of a wireless resource, for example.

Then, the content server selection unit124determines whether or not there is a pattern of the link aggregation in which it is estimated that a throughput higher than a throughput of wireless communication between the femtocell base station100and the terminal500is obtained, on the basis of two measurement results (S82). That is, the content server selection unit124compares a throughput of wireless communication obtained by the second measurement unit126with each throughput from the first candidate #331 to the first candidate #316 obtained by the first measurement unit123so as to determine whether or not there is a first candidate of which a throughput is higher than the throughput of wireless communication.

When there is no pattern of the first candidate of which a throughput is higher than the throughput of wireless communication (No in S82), the content server selection unit124directly sets a pattern of the first candidate as a pattern of the second candidate (S84).

Subsequently, the content server selection unit124selects a pattern of the link aggregation in which it is estimated that the highest throughput is obtained, for a pattern of the second candidate (S85).

Accordingly, when there is no pattern of the link aggregation in which it is assumed that a throughput higher than the throughput of wireless communication between the femtocell base station100and the terminal500is obtained (No in S82), a pattern of the link aggregation is selected irrespective of a processing load in the femtocell base station100.

That is, an end-to-end throughput between the terminal500and the content server400-2and between the terminal500and the content server400-3is a throughput which is realized by a selected pattern of the link aggregation. When the number of constituent IP routes is larger than a predetermined threshold value, a processing load of the femtocell base station100is also increased. However, in this case, a pattern of the link aggregation which is selected by the content server selection unit124exhibits the best end-to-end throughput realizable between the terminal500and the content server400-2, so that it may be said that favorable selection has been performed.

On the other hand, when there is the first candidate in which it is estimated that a throughput higher than the throughput of wireless communication is obtained (Yes in S82), the content server selection unit124changes the number of constituent IP routes on the basis of a measurement result (S83).

For example, a case in which the following results are obtained as measurement results of a throughput is considered. 1. First candidate #331: IP route #1+IP route #2-b+IP route #3 leading to the content server400-2, 2. First candidate #332: IP route #2+IP route #1-b+IP route #3-b leading to the content server400-3, 3. First candidate #321: IP route #1+IP route #2-b leading to the content server400-2, 4. First candidate #323: IP route #1+IP route #3 leading to the content server400-2, 5. First candidate #324: IP route #2-b+IP route #3 leading to the content server400-2, 6. First candidate #325: IP route #2+IP route #1-b leading to the content server400-3, 7. Wireless communication between the femtocell base station and the terminal, 8. First candidate #326: IP route #2+IP route #3-b leading to the content server400-3, 9. First candidate #328: IP route #1-b+IP route #3-b leading to the content server400-3, 10. First candidate #311: IP route #1 leading to the content server400-2, 11. First candidate #312: IP route #2-b leading to the content server400-2, 12. First candidate #313: IP route #3 leading to the content server400-2, 13. First candidate #314: IP route #2 leading to the content server400-3, 14. First candidate #315: IP route #1-b leading to the content server400-3, 15. First candidate #316: IP route #3-b leading to the content server400-3

In the above measurement results, numbers on the left side represent rank orders in a descending order of throughputs, in which “1” represents the highest throughput and “15” represents the lowest throughput. A throughput of wireless communication between the femtocell base station100and the terminal500represents the “seventh” throughput among patterns of the first candidates.

First candidates in which it is estimated a throughput higher than the throughput of wireless communication between the femtocell base station100and the terminal500is obtained are six candidates which are from the first candidate #331 to the first candidate #325. Among these six patterns from the first candidate #331 to the first candidate #325, the number of IP routes in a pattern using the smallest number of IP routes is “2”. In this case, the content server selection unit124changes the number of constituent IP routes which is determined in S44from “3” to “2”.

Subsequently, the content server selection unit124selects a pattern of the link aggregation which is constituted by the changed number of constituent IP routes as the second candidate among the first candidates (S84). In the example of the above measurement results, the content server selection unit124sets six patterns from the first candidate #321 to the first candidate #328 as the second candidates (from second candidate #321 to second candidate #328).

Then, the content server selection unit124selects a pattern of the second candidate in which it is estimated that the highest throughput is obtained among the second candidates of patterns of the link aggregation (S85). In the example of the above measurement results, the content server selection unit124selects the second candidate #321.

An end-to-end throughput between the terminal500and the content server400-2and between the terminal500and the content server400-3depends on a throughput of wireless communication between the femtocell base station100and the terminal500. For example, even if a pattern of the link aggregation in which it is estimated that a throughput between the femtocell base station100and the content server400-2and between the femtocell base station100and the content server400-3is highest is selected, an end-to-end throughput does not become to be about a throughput of a wired zone when a throughput of wireless communication is lower than the throughput between the femtocell base station100and the content server400-2and between the femtocell base station100and the content server400-3.

On the other hand, as the number of IP routes constituting a pattern of the link aggregation is smaller, a load of the femtocell base station100is decreased. In the example of the above measurement results, a processing load of the femtocell base station100is more decreased in a case in which the number of IP routes is “2” than a case in which the number of IP routes is “3”.

An end-to-end throughput depends on a throughput of wireless communication. Therefore, at least when any pattern of the link aggregation which exhibits a throughput higher than the throughput of wireless communication is selected, patterns of the link aggregation in which the number of constituent IP routes is “2” and a processing load of the femtocell base station100is not equally high are equally favorable for a throughput and a processing load.

However, a throughput of wireless communication may vary depending on a wireless environment or the like, and a throughput may become higher than a measurement result measured by the second measurement unit126, for example. Given that a throughput of wireless communication fluctuates to be increased depending on a wireless environment or the like, it is most favorable to select a pattern of which a throughput is estimated to be highest among patterns of the link aggregation in which a processing load of the femtocell base station100is not equally high.

Accordingly, the content server selection unit124selects a pattern in which it is estimated that a throughput in a wired zone is higher among constituent IP routes in which a processing load of the femtocell base station100is not high, for example, in the light of a processing performance of the femtocell base station100. For example, in the example of the above-mentioned measurement results, the number of IP routes in which a processing load of the femtocell base station100does not become high is set as “2” (S83) and the second candidate #321 exhibiting the highest throughput among the patterns of the number of IP routes “2” is selected (S85).

Accordingly, it is possible to select a pattern exhibiting a higher throughput among patterns of the link aggregation in which a processing load of the femtocell base station100does not become high, for example. A throughput of wireless communication may vary as described above and a throughput equivalent to that in a wired zone may be obtained. Accordingly, such selection enables improvement of an end-to-end throughput between the terminal500and the content server400-2and between the terminal500and the content server400-3.

Here, the content server selection unit124may also select a pattern in which the number of IP routes is “3” such as the second candidate #331 and the second candidate #332 as a pattern of the link aggregation in which it is estimated that the highest throughput is obtained, for example. However, in this case, a processing load of the femtocell base station100is increased compared to a pattern in which the number of IP routes is “2” such as the second candidate #321. Further, an end-to-end throughput between the terminal500and the content server400-2and between the terminal500and the content server400-3may become a throughput of wireless communication and become lower than a throughput in a wired zone, for example. Accordingly, such selection may not bring improvement of an end-to-end throughput.

Subsequently, the content server selection unit124selects the content server400-2or400-3which is coupled by a pattern of the link aggregation in which a throughput is estimated to be highest (S48). For example, the content server selection unit124selects the content server400-2based on the IP route #1 and the IP route #2-b (the second candidate #321).

Thus, in the third embodiment, it is possible to select the content server400-2or400-3based on a pattern in which a processing load of the femtocell base station100is lower, among patterns of the link aggregation in which a throughput equivalent to a throughput of wireless communication is obtained.

Here, in the third embodiment, the content server selection unit124changes the number of constituent IP routes from “3” to “2”. However, when a throughput of wireless communication is lower than the above-described example, the content server selection unit124may change the number of constituent IP routes to “1”. In this case, the content server selection unit124selects a pattern of the link aggregation which is constituted by a single route. In such selection, a throughput between the terminal500and the content server400-2and between the terminal500and the content server400-3is a throughput which is realized by wireless communication as a result. Accordingly, it may be said that favorable selection in which a processing load of the femtocell base station100is lower than the above-mentioned example is performed.

Other Embodiments

In the second and third embodiments, the femtocell base station100has been described as an example of a communication device. For example, a macro base station is also capable of executing what has been described in the second and third embodiments instead of the femtocell base station100. In this case, the macro base station may be coupled to a network other than the ISP200, for example, and it is sufficient that the macro base station is coupled with the content servers400-2and400-3via any network. Further, a device, other than the base station, such as gateway and a router which is disposed between a base station and the content server400-2and between the base station and the content server400-3may be employed as a communication device. In this case, the content server information acquisition unit122, the first measurement unit123, and the content server selection unit124may be provided to this device, for example.

Further, in description of the examples of the second and third embodiments, the number of content servers is two as the content servers400-2and400-3. For example, the number of content servers which are coupled with the femtocell base station100may be three or more. The femtocell base station100estimates a throughput of an IP route leading to each content server, selects a pattern of the link aggregation exhibiting the highest throughput, and selects the content server400-2or400-3, being able to execute processing in the same manner as the second and third embodiments.

In this application, for example, “connected to” is able to be replaced with “coupled to”. Moreover, for example, when an element is referred to as being “connected to” or “coupled to” another element, it can be directly connected or coupled to the other element or intervening elements may be present. So do “connecting to”, “coupling to”, “connection to”, “coupling to” and so on.