JP5921050B2 - Wireless terminal, system, and program for selecting base station used for carrier aggregation - Google Patents

Description

  The present invention relates to a carrier aggregation technique between a radio terminal and a base station.

  In recent years, LTE (Long Term Evolution) -Advanced with a cellular system flow and WiMAX2 (Worldwide Interoperability for Microwave with a fixed wireless access system flow) to realize a high-speed mobile wireless access service as a carrier side network Access, IEEE802.16m) has attracted attention. A “multi-carrier” method or a “carrier aggregation” method that secures a wide bandwidth by bundling a plurality of frequency bands can be applied to these technologies.

  According to the “multi-carrier” scheme, a wide bandwidth can be secured by bundling a plurality of different carriers (frequency carriers) between one wireless terminal and one base station. The wireless terminal divides transmission data into a plurality of pieces, modulates the divided pieces of transmission data into different carrier waves, and transmits them simultaneously to one base station. In this case, the base station integrates data based on a plurality of carriers. Further, according to the “carrier aggregation” method, a wide bandwidth can be secured by bundling a plurality of wireless routes between one wireless terminal and a plurality of base stations. The wireless terminal divides the transmission data into a plurality of pieces, and transmits the divided pieces of transmission data simultaneously to different base stations. In this case, a packet gateway that integrates a plurality of data via these different base stations is required in the carrier network of the wide area wireless network. These two systems have an advantage that they are resistant to propagation interference affecting a specific frequency because one transmission data is transmitted via a plurality of different carriers or wireless lines.

  In addition, as a “carrier aggregation” scheme, for each carrier, the first base station that is the handover source transmits a handover command to be transferred to the wireless terminal and the second base station that is the handover destination, and the wireless terminal There is also a technique for handing over to the second base station every time (see, for example, Patent Document 1). According to this technology, the base station for each carrier to which the wireless terminal 1 should be connected can be controlled from the communication carrier network.

  Furthermore, as a “carrier aggregation” method, for example, WiMAX as a wide area wireless network and a wireless LAN as a narrow area wireless network can be bundled and communicated. As a result, a wider bandwidth can be secured. However, a packet gateway that integrates a plurality of data via these different wireless networks is required between the local wireless terminal and the counterpart device.

  In addition, as a user-side network, there are increasing usage forms in which a plurality of wireless terminals are accommodated under one “mobile router” as an access point. On the other hand, a general mobile router is connected to a wireless terminal via a wireless LAN, and on the other hand is connected to a base station via a WiMAX or 3G wide area wireless network. For example, a wireless terminal such as a tablet terminal can be connected to the Internet regardless of the location by connecting to a mobile router via a wireless LAN.

JP 2011-097443 A

  Here, the wireless terminal directly communicates with the base station of the wide area wireless network and communicates using the carrier aggregation method by connecting with the access point (or mobile router) of the narrow area wireless network. Can be assumed. At this time, it is assumed that the mobile router is connected to the base station of the wide area wireless network on the other side.

  However, at this time, when the wireless terminal is directly connected to the base station of the wide area wireless network and the mobile router is also connected to the same base station, the throughput improvement effect in the carrier aggregation is maximized and the specific frequency is affected. The advantage of being strong against propagation interference is not obtained. Moreover, in order to select a base station having the highest wireless quality (for example, the highest reception level) among a plurality of detected base stations, a wireless terminal or a mobile router usually has the same base if it is at the same position. The station will be selected.

Therefore, the present invention is directed to a case where a wireless terminal performs a carrier aggregation scheme using a base station via a wide-area wireless network and an access point via a narrow-area wireless network, so that different carriers or It is an object of the present invention to provide a wireless terminal, a system, and a program that can configure a communication path using a wireless line and that can configure a communication path so as to be resistant to propagation interference.

According to the present invention, in the wireless terminal to be connected to multiple base stations,
Carrier aggregation means for transmitting and receiving the first data transmitted and received via the first base station and the second data transmitted and received via the second base station as a single association by the multihoming function ;
The first base station identifier of the first base station, a base station identifier obtaining means for obtaining from a first base station or other device,
And having a connection base station selection means second base station identifier that is different from the first base station identifier to connect with respect to the second base station granted.

According to another embodiment of the wireless terminal of the present invention,
The carrier aggregation means is configured to condense the first data transmitted / received to / from the first base station and the second data transmitted / received to / from the second base station as one session, in order to collect as one session. It is also preferable to use.

According to another embodiment of the wireless terminal of the present invention,
If the wireless terminal has already transmitted and received both the first data and the second data to the first base station of the first base station identifier,
The connected base station selection means preferably controls to hand over the second data to the second base station having the second base station identifier.

According to another embodiment of the wireless terminal of the present invention,
Both the first base station and the second base station are preferably base stations arranged in a wide area wireless network.

According to another embodiment of the wireless terminal of the present invention,
The first base station is a base station located in a wide area wireless network,
The second base station is also preferably an access point that communicates with a wireless terminal via a narrow-area wireless network using a wide-area wireless network as a backhaul and relays data for the wireless terminal.

According to another embodiment of the wireless terminal of the present invention,
The access point is preferably a mobile router or a hotspot access point.

According to the present invention, a system having a plurality of base stations and a base station selection server capable of communicating via a wide area wireless network together with the wireless terminal described above ,
Another device with which the wireless terminal communicates is a base station selection server,
The base station transmits an access point identifier for the wireless terminal and a location registration message including the base station identifier to the base station selection server,
The base station selection server registers an access point identifier for the wireless terminal and the base station identifier for each base station,
The wireless terminal transmits the access point identifier of the already connected base station to the base station selection server, and the base station selection server returns a base station identifier corresponding to the access point identifier to the wireless terminal.
It is characterized by that.

According to the present invention, in a program for causing a computer installed in a wireless terminal connected to a plurality of base stations to function,
Carrier aggregation means for transmitting and receiving the first data transmitted and received via the first base station and the second data transmitted and received via the second base station as a single association by the multihoming function;
Base station identifier acquisition means for acquiring the first base station identifier of the first base station from the first base station or another device;
Connected base station selecting means for connecting to a second base station to which a second base station identifier different from the first base station identifier is assigned;
And making the computer function.

According to another embodiment of the program for the wireless terminal of the present invention ,
The carrier aggregation means uses SCTP to converge the first data transmitted / received to / from the first base station and the second data transmitted / received to / from the second base station as one session.
It is also preferable to make the computer function.

According to another embodiment of the program for the wireless terminal of the present invention ,
If the wireless terminal has already transmitted and received both the first data and the second data to the first base station of the first base station identifier,
The connected base station selection means controls to hand over the second data to the second base station having the second base station identifier.
It is also preferable to make the computer function.

According to the wireless terminal, system, and program of the present invention, when the wireless terminal executes the carrier aggregation scheme using the base station via the wide area wireless network and the access point via the narrow area wireless network, the throughput is high. It is possible to configure a communication path using different carrier waves or wireless channels so as to be maximum, and to configure a communication path so as to be resistant to propagation obstacles.

It is a system configuration diagram in the present invention. It is a 1st sequence diagram in this invention. It is a 2nd sequence diagram in this invention. It is a 3rd sequence diagram in the present invention. It is a 4th sequence diagram in this invention. It is a function block diagram of the radio | wireless terminal in this invention. It is a system configuration figure of other embodiments in the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram according to the present invention.

According to FIG. 1, a user-operable wireless terminal 1 can communicate with a base station 3 via a wide area wireless network and can communicate with a mobile router 2 via a narrow area wireless network. The wireless terminal 1 is, for example, a mobile phone, a smartphone, or a tablet terminal. The wide area wireless network is, for example, WiMAX, LTE, or 3G (3rd Generation), and a plurality of base stations 3 are arranged. The narrow area wireless network is, for example, a wireless local area network (LAN) or Bluetooth (registered trademark) .

  Further, according to FIG. 1, it is assumed that the user has a mobile router 2 along with the wireless terminal 1. Of course, the mobile router 2 may be a fixed hotspot access point that is operated and managed by a telecommunications carrier, and may have a backhaul over a wireless line. The mobile router 2 is connected to the wireless terminal 1 via a narrow area wireless network and also connected to the base station 3 via a wide area wireless network. That is, the mobile router 2 relays user data between the wide area wireless network and the narrow area wireless network.

  The wireless terminal 1 can simultaneously communicate with both the base station 3 via the wide area wireless network and the mobile router 2 via the narrow area wireless network. Here, the wireless terminal 1 executes a carrier aggregation function in which the wide area wireless network and the narrow area wireless network are bundled.

  A packet gateway 4 is provided at the edge of the wide area wireless network that is operated and managed by the communication carrier. The packet gateway 4 opposes the carrier aggregation function of the wireless terminal 1 and focuses a plurality of data received via different base stations 3 into one data. The collected data is transferred to a destination apparatus (server) 5 via the Internet. On the contrary, when the destination is the wireless terminal 1, the data received from the counterpart device 5 is divided into a plurality of data, and each data is transmitted via a different base station 3.

Furthermore, according to FIG. 1, a base station selection server 6 is connected to the Internet. The base station selection server 6 is accessed from the wireless terminal 1 and the mobile router 2 and stores the base station identifier of the base station connected to the access point in association with the access point identifier in the narrow area wireless network.
Access point identifier <-> Base station identifier

Here, specifically, the base station selection server 6 preferably further combines the MAC (Media Access Control) address of the mobile router (MR) 1 with the access point identifier, and stores the base station identifier in association with each other. .
Access point identifier, MR MAC address <-> Base station identifier

  In the case of a wireless LAN, the access point identifier is specifically an SSID (Service Set IDentifier). The SSID is a maximum of 32 alphanumeric characters for avoiding interference, and can be communicated only between the wireless terminal and the access point having the same SSID. The MAC address of the mobile router 2 is specifically a 48-bit hexadecimal number. Further, the base station identifier is a BSID (Base Station IDentifier) assigned to the base station.

  FIG. 2 is a first sequence diagram in the present invention.

(S21) The mobile router 2 establishes communication with the first base station 3A via the wide area wireless network (for example, WiMAX), and the wireless terminal 1 communicates with the mobile router 2 in the narrow area wireless network ( For example, communication via a wireless LAN is established. As a result, the wireless terminal 1 can connect to the wide area wireless network via the mobile router 2 and communicate with the counterpart device 5 via the Internet.
Note that the wireless terminal 1 can usually detect radio waves from a plurality of base stations 3 in the wide area wireless network regardless of the position. Therefore, the wireless terminal 1 can always store the base station identifiers of a plurality of base stations 3 that can be connected via the wide area wireless network.
(S22) At this time, it is assumed that the wireless terminal 1 generates a trigger for starting carrier aggregation. For example, a case is assumed where the amount of communication between the wireless terminal 1 and the counterpart device 5 increases, and wireless resources with a wide bandwidth are required.
(S23) The wireless terminal 1 requests the mobile router 2 for the first base station identifier of the first base station to which the mobile router (access point) 2 connects via the wide area wireless network. The wireless terminal 1 transmits a base station identifier request message to the mobile router 2.
(S24) On the other hand, the mobile router 2 responds to the wireless terminal 1 with the first base station identifier (BSID1) of the first base station to which the mobile router 2 is connected via the wide area wireless network.
(S25) Here, the wireless terminal 1 selects a second base station identifier different from the first base station identifier.
(S26) The radio terminal 1 executes a communication establishment sequence for the second base station to which the selected second base station identifier is assigned. As a result, the wireless terminal 1 communicates with the first base station of the wide area wireless network via the mobile router 2 via the wireless LAN, and at the same time, directly communicates with the second base station of the wide area wireless network. can do.
(S27) Then, the wireless terminal 1 executes the carrier aggregation function with the packet gateway 4 using both the wide area wireless network of the base station 3 and the narrow area wireless network of the mobile router 2.

  FIG. 3 is a second sequence diagram in the present invention.

(S31) First, the wireless terminal 1 establishes communication with the first base station 3A via a wide area wireless network (for example, WiMAX). Accordingly, the wireless terminal 1 can communicate with the counterpart device 5 via the Internet via the wide area wireless network.
Further, the mobile router 2 has established communication with the first base station 3A via a wide area wireless network (for example, WiMAX).
(S32) At this time, it is assumed that a trigger for starting carrier aggregation occurs in the wireless terminal 1 (similar to S22 in FIG. 2). Here, the wireless terminal 1 establishes communication with the mobile router 2 via a narrow area wireless network (for example, a wireless LAN).
(S33) Then, the wireless terminal 1 requests the mobile router 2 for the first base station identifier of the first base station to which the mobile router (access point) 2 is connected via the wide area wireless network (FIG. 2). Of S22). For example, the wireless terminal 1 transmits a base station identifier request message to the mobile router 2.
(S34) On the other hand, the mobile router 2 responds to the wireless terminal 1 with the first base station identifier (BSID1) of the first base station to which the mobile router 2 is connected via the wide area wireless network (FIG. 2 and S24).
(S35) Here, the wireless terminal 1 selects a second base station identifier different from the first base station identifier (similar to S25 in FIG. 2).
(S36) From the first base station 3A having the first base station identifier that has already established the communication to the second base station 3B having the second base station identifier, the wireless terminal 1 has established communication over the wide area wireless network. Hand over. That is, the wireless terminal 1 executes a communication establishment sequence with respect to the second base station 3B. As a result, the wireless terminal 1 communicates with the first base station of the wide area wireless network via the mobile router 2 via the wireless LAN, and at the same time, directly communicates with the second base station of the wide area wireless network. can do.
(S37) Then, the wireless terminal 1 executes a carrier aggregation function with the packet gateway 4 using both the wide area wireless network of the base station 3 and the narrow area wireless network of the mobile router 2 (see FIG. 2 and S27).

  FIG. 4 is a third sequence diagram in the present invention.

According to FIG. 4, compared with FIG. 2, the base station selection server 6 is connected to the Internet.
(S41) The mobile router 2 establishes communication with the first base station 3A via the wide area wireless network (for example, WiMAX), and the wireless terminal 1 communicates with the mobile router 2 in the narrow area wireless network ( For example, communication via a wireless LAN is established. As a result, the wireless terminal 1 can connect to the wide area wireless network via the mobile router 2 and communicate with the counterpart device 5 via the Internet (similar to S21 in FIG. 2).
Here, the mobile router 2 transmits the first base station identifier associated with the SSID and the MAC address to the base station selection server 6. That is, the mobile router 2 transmits a base station identifier registration message including the SSID, MAC address, and first base station identifier to the base station selection server 6. The base station selection server 6 stores the first base station identifier in association with the SSID and MAC address, and returns a response message to the mobile router 2.
(S42) At this time, it is assumed that a trigger for starting carrier aggregation occurs in the wireless terminal 1 (similar to S22 in FIG. 2).
(S43) The wireless terminal 1 requests the base station selection server 6 for the first base station identifier of the first base station to which the mobile router (access point) 2 connects via the wide area wireless network. The wireless terminal 1 transmits a base station identifier request message including the SSID and the MAC address of the mobile router to the base station selection server 6 via the mobile router 2. This request message includes the SSID and the MAC address of the mobile router.
(S44) In response to this, the base station selection server 6 searches for a base station identifier based on the received SSID and MAC address, and returns a response message including the base station identifier to the wireless terminal 1. Here, the first base station identifier (BSID1) of the first base station to which the mobile router 2 is connected via the wide area wireless network is returned to the wireless terminal 1.
(S45) On the other hand, the wireless terminal 1 selects a second base station identifier different from the first base station identifier (similar to S25 in FIG. 2).
(S46) The wireless terminal 1 executes a communication establishment sequence for the second base station to which the selected second base station identifier is assigned (similar to S26 in FIG. 2). As a result, the wireless terminal 1 communicates with the first base station of the wide area wireless network via the mobile router 2 via the wireless LAN, and at the same time, directly communicates with the second base station of the wide area wireless network. (Similar to S26 in FIG. 2).
(S47) Then, the wireless terminal 1 executes a carrier aggregation function with the packet gateway 4 using both the wide area wireless network of the base station 3 and the narrow area wireless network of the mobile router 2 (see FIG. 2 and S27).

  FIG. 5 is a fourth sequence diagram in the present invention.

(S51) First, the wireless terminal 1 establishes communication with the first base station 3A via a wide area wireless network (for example, WiMAX). Accordingly, the wireless terminal 1 can communicate with the counterpart device 5 via the Internet via the wide area wireless network (similar to S41 in FIG. 4).
The mobile router 2 establishes communication with the first base station 3A via the wide area wireless network. Here, the mobile router 2 transmits the first base station identifier associated with the SSID and the MAC address to the base station selection server 6. The mobile router 2 transmits a base station identifier registration message to the base station selection server 6. The base station selection server 6 stores the first base station identifier in association with the SSID and MAC address, and returns a response message to the mobile router 2.
(S52) At this time, it is assumed that a trigger for starting carrier aggregation occurs in the wireless terminal 1 (similar to S32 in FIG. 3). Here, the wireless terminal 1 starts to establish communication with the mobile router 2 via a narrow area wireless network (for example, wireless LAN).
(S53) The wireless terminal 1 is connected to the mobile router (access point) 2 via the wide area wireless network without waiting for establishment of communication with the mobile router 2 via the narrow area wireless network. The base station selection server 6 is requested for the first base station identifier. The wireless terminal 1 transmits a base station identifier request message including the SSID and the MAC address of the mobile router to the base station selection server 6 (similar to S43 in FIG. 4).
(S54) In response to this, the base station selection server 6 searches for a base station identifier based on the received SSID and MAC address, and returns a response message including the base station identifier to the wireless terminal 1. Here, the first base station identifier (BSID1) of the first base station to which the mobile router 2 is connected via the wide area wireless network is returned to the wireless terminal 1 (similar to S44 in FIG. 4). Until then, the wireless terminal 1 establishes communication with the mobile router 2 via the narrow area wireless network.
(S55) On the other hand, the radio terminal 1 selects a second base station identifier different from the first base station identifier (similar to S45 in FIG. 4).
(S56) The radio terminal 1 performs handover from the first base station 3A having the first base station identifier that has already established communication to the second base station 3B having the second base station identifier. That is, the wireless terminal 1 executes a communication establishment sequence with respect to the second base station 3B. As a result, the wireless terminal 1 communicates with the first base station of the wide area wireless network via the mobile router 2 via the wireless LAN, and at the same time, directly communicates with the second base station of the wide area wireless network. (Similar to S36 in FIG. 3).
(S57) The wireless terminal 1 executes the carrier aggregation function with the packet gateway 4 using both the wide area wireless network of the base station 3 and the narrow area wireless network of the mobile router 2 (see FIG. 3 and S37).

  FIG. 6 is a functional configuration diagram of the wireless terminal according to the present invention.

  According to FIG. 6, the wireless terminal 1 includes a narrow area wireless network communication unit 101, a wide area wireless network communication unit 102, a carrier aggregation unit 11, an IP (Internet Protocol) layer 12, a TCP (Transmission Control Protocol) / A UDP (User Datagram Protocol) layer 13, an application layer 14, a base station identifier acquisition unit 15, and a connected base station selection unit 16 are included. These functional components excluding the wireless network communication units 101 and 102 are realized by executing a program that causes a computer installed in the wireless terminal to function.

  The narrow area wireless network communication unit 101 communicates with the mobile router 2, and the wide area wireless network communication unit 102 communicates with the base station 3.

  The carrier aggregation unit 11 is configured to collect the first data of the wide area wireless network communication unit 102 and the second data of the narrow area wireless network communication unit 101 as one session. Is used. “Multihoming” is provided as one function of SCTP. “Multihoming” functions as a host having a plurality of IP addresses that can address each of a plurality of network interfaces. Two paths can be combined into one association.

  The wireless terminal 1 configures a TCP / UDP layer 13, an IP layer 12, and a carrier aggregation unit 11 from the application layer 14 toward the lower layer.

  The base station identifier acquisition unit 15 acquires the first base station identifier of the first base station to which the mobile router 2 is connected via the wide area wireless network from the access point or another device (S23 and FIG. 2). (S24, S33 and S34 in FIG. 3, S43 and S44 in FIG. 4, and S53 and S54 in FIG. 5 are executed).

  The connection base station selection unit 16 uses the communication management layer 17 to connect to the second base station assigned with the second base station identifier different from the first base station identifier via the wide area wireless network. (S25 in FIG. 2, S35 in FIG. 3, S44 in FIG. 4, and processing similar to S55 in FIG. 5 are executed).

  FIG. 7 is a system configuration diagram of another embodiment of the present invention.

  According to FIG. 7, as compared with FIG. 1, the mobile router 2 can communicate simultaneously with both the first base station and the third base station via the wide area wireless network. The mobile router 2 also transmits the first data transmitted / received to / from the first base station via the wide area wireless network and the third data transmitted / received to / from the third base station via the wide area wireless network. It has a carrier aggregation unit that collects and transmits as a session. According to such a configuration, the wireless terminal 1 can secure a wider bandwidth and is resistant to propagation interference based on a specific frequency.

As described above in detail, according to the wireless terminal, system, and program of the present invention, the wireless terminal uses a base station via a wide area wireless network and an access point via a narrow area wireless network. When executing the aggregation method, it is possible to configure a communication path using different carrier waves or wireless channels so as to maximize the throughput, and to configure a communication path so as to be resistant to propagation failure.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Wireless terminal 101 Narrow-area wireless network communication part 102 Wide-area wireless network communication part 11 Carrier aggregation part 12 IP layer 13 TCP / UDP layer 14 Application layer 15 Base station identifier acquisition part 16 Connected base station selection part 2 Mobile router, access point 3 Base station 4 Packet gateway 5 Destination device 6 Base station selection server

Claims (10)

In the wireless terminal to connect to multiple base stations,
Carrier aggregation means for transmitting and receiving the first data transmitted and received via the first base station and the second data transmitted and received via the second base station as a single association by the multihoming function ;
The first base station identifier of the first base station, a base station identifier obtaining means for obtaining from a first base station or other device,
Wireless terminal; and a connection base station selection means second base station identifier that is different from the first base station identifier to connect with respect to the second base station granted.   The carrier aggregation means collects the first data transmitted / received to / from the first base station and the second data transmitted / received to / from the second base station as one session in order to converge the stream control transmission protocol SCTP (Stream Control Transmission Protocol). )
The wireless terminal according to claim 1.   If the wireless terminal has already transmitted and received both the first data and the second data to the first base station of the first base station identifier,
  The connected base station selection means controls to hand over the second data to the second base station having the second base station identifier.
The wireless terminal according to claim 1, wherein the wireless terminal is a wireless terminal.   Both the first base station and the second base station are base stations arranged in a wide area wireless network.
The wireless terminal according to claim 1, wherein the wireless terminal is a wireless terminal.   The first base station is a base station located in a wide area wireless network,
  The second base station is an access point that communicates with the wireless terminal via the narrow-area wireless network using the wide-area wireless network as a backhaul and relays data for the wireless terminal.
The wireless terminal according to claim 1, wherein the wireless terminal is a wireless terminal.   The access point is a mobile router or hotspot access point
The wireless terminal according to claim 5.   A system having a plurality of base stations and a base station selection server that can communicate with a wireless terminal according to claim 5 or 6 via a wide area wireless network,
  The other device with which the wireless terminal communicates is the base station selection server,
  The base station transmits an access point identifier for the wireless terminal and a location registration message including the base station identifier to the base station selection server,
  The base station selection server registers an access point identifier for the wireless terminal and the base station identifier for each base station,
  The wireless terminal transmits an access point identifier of an already connected base station to the base station selection server, whereas the base station selection server transmits a base station identifier corresponding to the access point identifier to the wireless station. Reply to device
A system characterized by that.   In a program for causing a computer mounted on a wireless terminal connected to a plurality of base stations to function,
  Carrier aggregation means for transmitting and receiving the first data transmitted and received via the first base station and the second data transmitted and received via the second base station as a single association by the multihoming function;
  Base station identifier acquisition means for acquiring the first base station identifier of the first base station from the first base station or another device;
  Connected base station selecting means for connecting to a second base station to which a second base station identifier different from the first base station identifier is assigned;
A program for a wireless terminal, which causes a computer to function.   The carrier aggregation means collects the first data transmitted / received to / from the first base station and the second data transmitted / received to / from the second base station as one session in order to converge the stream control transmission protocol SCTP (Stream Control Transmission Protocol). )
The program for a wireless terminal according to claim 8, wherein the computer functions as described above.   If the wireless terminal has already transmitted and received both the first data and the second data to the first base station of the first base station identifier,
  The connected base station selection means controls to hand over the second data to the second base station having the second base station identifier.
10. The program for a wireless terminal according to claim 8, wherein the computer is caused to function as described above.

Images