JP2007243718A - Hand-over control method, connection station, and radio base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a processing load of a connection station which exchanges frames with an external network in a centralized manner when setting a multicast path during multicast hand-over. <P>SOLUTION: A connection station 1 includes a transfer table mapping a plurality of radio base stations BS1-BS3 respectively at bit positions of location codes indicating the radio base stations BS1-BS3 where mobile terminals MH#1, MH#2 are located and when unicasting IP packets destined to the mobile terminals MH#1, MH#2 to one radio base station, a U/M bit indicative unicast or multicast in a destination MAC address is set to unicast but when multicasting the IP packets to a plurality of radio base stations, the U/M bit is set to multicast and an address disposing a location code in a subsequent address part is generated and transferred to the radio base stations. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a handover control method for handover by multicast, a connection station, and a radio base station.

  Currently, in mobile terminal communication such as a mobile phone, a mobile control method for IP communication is being studied. However, in local mobility limited to an area or an administrator, the mobile terminal changes its IP address when moving. A method of performing mobility control without delay is being studied (such as the IETF netlmm group). In such a request, it is considered that a device on the network side supports movement processing of a mobile terminal and performs control so that an IP packet is transferred to an appropriate base station to which the mobile terminal is connected. Yes.

  A connection station for relaying between a mobile terminal and an external IP network, a radio base station (hereinafter also simply referred to as a base station) to which the mobile terminal is connected, and a plurality of relay stations connecting the connection station and the radio base station In a configured access network, in order for a mobile terminal to perform handover between radio base stations, as a method for transferring a frame addressed to the corresponding mobile terminal from the connection station to the two radio base stations of the handover source and the handover destination, the connection station And a method of transmitting a plurality of unicast frames by copying a frame, and a method of transmitting a multicast frame that can be transferred to two base stations (for example, Patent Document 1 below). However, the method of copying a frame and transmitting a plurality of unicast frames at the connecting station has a problem that the processing load of the connecting station is high, and also has a problem that the use band of the network increases. A method of transmitting a multicast frame only to two base stations is desirable. In the case where the network supports such movement, the present invention provides a handover control method for reducing the load on a connection station when using a multicast frame when transmitting a frame of the same mobile terminal to a plurality of base stations, a connection station, and It relates to a radio base station.

  FIG. 8 shows a configuration example of a conventional network. The network shown in FIG. 8 has a connection station (MAP: Mobile Anchor Point) 1 serving as a connection point with an external network, and a wireless base station BS1 to BS5 as a relay device, a relay station (Bridge) 2 of Ethernet (registered trademark). 3 is an example of a layer 2 network that is connected using 3. In this network, the connecting station 1 manages the location information of the mobile terminals MH # 1 and MH # 2, and IP packets addressed to the mobile terminals MH # 1 and MH # 2 from the external network are connected to the connecting station 1 and the relay station. 2 and 3 are transmitted to the base station BS to which the mobile terminals MH1 and MH2 are connected. As the configuration of the destination access network, the connection station and the base station terminate IP, and the user packet is tunneled at Layer 3 (such as IP-in-IP), or the connection station and base station do not terminate IP. A case where a user frame is tunneled at layer 2 (MAC-in-MAC) can be considered. However, in any case, the layer 2 destination address of the user data transmitted by the connecting station is the MAC address of the base station to which the corresponding mobile terminal belongs or an appropriate L2 multicast address including the corresponding base station BS.

An operation when the mobile terminal MH performs a handover in such a network will be described. It is assumed that the mobile terminal MH # 1 currently connected to the base station BS2 has moved to a position where radio waves can be received from the base station BS1. At this time, when the mobile terminal MH # 1 recognizes that the connectable base station is the base station BS1 based on beacon information from the base station BS1, for example, the mobile terminal MH # 1 transmits a frame addressed to the mobile terminal MH # 1 to the base station BS2. Request base station BS2 and base station BS1 to perform multicasting. Receiving this request, the base station BS2 requests the connecting station 1 to update the location information of the mobile terminal MH # 1 to the base stations BS1 and BS2 via the relay station 2. By changing the destination address to an appropriate multicast address based on this location update in the connecting station 1, it is possible to realize transmission of frames to a plurality of base stations BS1 and BS2. In this way, by using multicast, it is possible to transfer a frame to a plurality of base stations BS1 and BS2 while suppressing an increase in frame duplication load at the connection station 1 and further reducing consumption of a network use band.
JP 2003-37626 A (Abstract)

  However, when such a multicast is used, in order for the connecting station 1 to manage the locations of the mobile terminals MH # 1 and MH # 2 and transmit frames to appropriate base stations, location management and destination multicast address mapping are performed. Necessary. These various management tables are shown in FIGS. 9 (a) and 9 (b). As shown in FIG. 9A, in order to transfer a frame to a plurality of base stations using multicast, a combination of base stations (BS1, BS2) necessary for transferring a frame to a plurality of base stations (BS1, BS2), ( It is necessary to assign and manage multicast addresses according to BS2, BS3) and (BS4, BS5). FIG. 9B shows a case where paging is performed on the mobile terminals MH # 1 and MH # 2 for receiving an incoming call when the mobile terminal is not connected to the base station due to an idle mode or the like. In order to transmit paging packets to the paging area and the corresponding area, it is conceivable to perform confirmation by multicast. In such a case, allocation and management of the multicast address for the corresponding area are also necessary. Become.

  In addition to such address allocation management, a transfer table for transferring packets addressed to actual mobile terminals is required as shown in FIG. For each ID (mobile terminal) indicating a user, this forwarding table transmits a frame to the paging area to which the user currently belongs, the base station (location information) being connected (and connection request is being made), and the corresponding base station. For the destination MAC address. The connecting station 1 uses this transfer table to construct and transfer an Ethernet frame for transmitting the received IP packet. Also, the connecting station 1 updates various position information and destination address in the transfer table of the corresponding mobile terminal by updating the location when the mobile terminal moves.

  Also, when forwarding by multicast, unlike ordinary unicast, it is necessary to set up a multicast group in the network so that the frame is forwarded only to an appropriate base station. In Ethernet, GMRP (GARP Multicast Registration Protocol; GARP: Generic Attribute Registration Protocol) is defined as a group management standard protocol. When performing group management using this, it is necessary for a node (host, bridge, etc.) participating in the group to notify the corresponding group. As a result, the bridge as a relay station can transmit a frame of the corresponding multicast address only to an appropriate port. For this purpose, each base station to be a node participating in the group (receiving node) must transmit a participation message to an appropriate address.

  This multicast setting operation is shown in FIGS. Since the multicast address management is performed collectively by the location management and address management node (here, the connecting station 1), each base station BS1 to BS5 connects to which multicast address it should participate. It is necessary to be notified from the station 1. For this reason, it is necessary for the connecting station 1 to notify the base stations BS1 to BS5 of all related multicast addresses and to instruct the multicast group participation processing. As described above, when performing frame transfer to a plurality of base stations by multicast, there is no frame duplication processing by the connecting station 1, but in addition to the unicast addresses of the base stations BS1 to BS5, combinations of the base stations BS1 to BS5 Multicast address assignment management and its setting management are required.

  In view of the above-described problems of the prior art, the present invention provides a handover control capable of reducing the processing load of a connection station that performs intensive transmission / reception of frames with an external network when setting a multicast path when performing handover by multicast. It is an object to provide a method, a connection station, and a radio base station.

To achieve the above object, the present invention provides an access network having a connection station connected to an external IP network and a plurality of radio base stations connected to the mobile terminal, wherein the mobile terminal performs handover between two radio base stations. A handover control method for transferring an IP packet addressed to the mobile terminal from the external IP network to the plurality of radio base stations,
The connecting station generates a location code indicating a wireless base station to which a packet is to be transferred for each mobile terminal based on a value of a corresponding bit with each identifier value assigned to the wireless base station as a bit position. Generated and sent a destination address containing.
By this method, since the connecting station can generate a multicast address only from the location information of the mobile terminal, the processing load on the connecting station can be reduced.

The generated destination address is always a multicast address.
By this method, since the connecting station can generate a multicast address only from the location information of the mobile terminal, the processing load on the connecting station can be reduced.

Further, the generated destination address is a unicast address when only one bit is set in the location code.
With this method, the connecting station can generate a unicast address only from the location information of the mobile terminal, so that the processing load on the connecting station can be reduced.

Further, when no bit is set in the location code of the destination mobile terminal when receiving a packet from the external IP network, the connecting station generates a multicast address using the location code and uses this address. Then, paging processing for searching for a radio base station to which the mobile terminal is connected is performed.
By this method, the connecting station can call the mobile terminal even if no bit is set in the location code of the mobile terminal that is the destination.

Further, the access network constitutes an area for grouping the plurality of radio base stations into a plurality of groups,
The generated destination address includes an area code indicating this area together with a location code.
By this method, the connecting station can call a destination mobile terminal.

In addition, when the currently connected mobile terminal is handed over, the radio base station uses the identifier value of the destination base station and its own base station when the identifier of the destination base station is notified. A location code in which a corresponding bit position is set is generated, a multicast address group is generated using the location code, and a group join message indicating participation in the multicast address group is output.
By this method, the connecting station can call a destination mobile terminal.

In order to achieve the above object, the present invention has a plurality of radio base stations to which a mobile terminal is connected, and the mobile terminal moves from the external IP network when performing handover between two radio base stations. A connection station that can be controlled to transfer IP packets addressed to a terminal to the plurality of radio base stations, belongs to an access network, and connects to the external IP network,
Location code generating means for generating a location code indicating a wireless base station that is a packet transfer destination for each mobile terminal, based on the value of the corresponding bit with the value of each identifier assigned to the wireless base station as a bit position;
Address generating means for generating and transmitting a destination address including the location code;
It was set as the structure to comprise.
With this configuration, the connecting station can generate a multicast address only from the location information of the mobile terminal, so that the processing load on the connecting station can be reduced.

Further, the address generation means always generates a multicast address.
With this configuration, the connecting station can generate a multicast address only from the location information of the mobile terminal, so that the processing load on the connecting station can be reduced.

Further, the address generating means generates a unicast address when only one bit is set in the location code.
With this configuration, the connecting station can generate a unicast address only from the location information of the mobile terminal, so that the processing load on the connecting station can be reduced.

Further, the address generation means generates a multicast address using the location code when no bit is set in the location code of the destination mobile terminal when receiving a packet from the external IP network,
Paging processing means for performing paging processing for searching for a radio base station to which the mobile terminal is connected using the multicast address;
Furthermore, it was set as the structure which comprises.
With this configuration, the connecting station can call the mobile terminal even if no bit is set in the location code of the destination mobile terminal.

Further, the access network constitutes an area for grouping the plurality of radio base stations into a plurality of groups,
The address generation means generates a destination address including an area code indicating the area together with a location code.
With this configuration, the connecting station can call a destination mobile terminal.

In order to achieve the above object, the present invention belongs to an access network having a connection station connected to an external IP network, and is a radio base station to which a mobile terminal connects,
When the currently connected mobile terminal is handed over, the location where the corresponding bit position is set using the identifier value of the destination base station and its own base station when the identifier of the destination base station is notified Location code generation means for generating code;
A group participation message output means for generating a multicast address group using the location code and outputting a group participation message indicating participation in the multicast address group;
It was set as the structure which has.
With this configuration, the connecting station can generate a multicast address only from the location information of the mobile terminal, so that the processing load on the connecting station can be reduced.

Further, when receiving the group participation message, a group participation determination means for determining whether or not to participate in the group of the received participation message,
Furthermore, it is characterized by having.
In addition, the group participation determination means sets a bit at a bit position indicated by its own identifier value among each bit of the location code included in the group address, and sets one or more other bits. If there is, the process of participating in the corresponding group is executed.
In addition, the group participation determination means, when each bit of the location code included in the group address, the bit of the bit position indicated by the value of its own identifier is set, and other bits are not set, The error message is transmitted using a destination multicast address using a location code in which no bit is set.
Further, the group participation determination means executes a participation process to a multicast address group generated using a location code in which only the bit position of the value of the corresponding identifier is set from the identifier set to itself at startup. Features.
Further, the group participation determination means generates a unicast address using a location code in which only the bit position of the value of the corresponding identifier is set from the identifier set to itself at the time of activation, and uses this as its own unicast address. It is characterized by setting.

  According to the present invention, since the connecting station can generate a multicast address only from the location information of the mobile terminal, the processing load on the connecting station can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
In the present invention, in order to simplify the management and mapping of the multicast address as the destination address of the forwarding frame in the network, the location information is mapped to the multicast address as shown in FIG. 1 for layer 2 Ethernet. Takes a multicast address configuration. Here, the Ethernet address (MAC address) is composed of 48 bits, and the first bit of the first 2 bits out of 48 bits is a bit (Unicast address) or a multicast address (Multicast address). U / M bit), and the second bit is a bit (G / L bit) indicating a global address or a local address.

  Therefore, in the present invention, both the first two bits are set to 1 and used as a local multicast address. Furthermore, 14 bits of the subsequent 46-bit address part are divided into a plurality of paging areas in the access network to form an area code indicating each area, and the remaining 32 bits are location information. A location code (Location Code) indicating a base station by a bit position is used. Here, the area code is for handling several base stations in one area for paging. By using this area code in the address, base stations having the same base station identifier (BSID) can be used redundantly for different areas, so that scalability can be improved. Here, the area code is 14 bits and the location code is 32 bits. However, the present invention is not limited to this, and other combinations of bit patterns may be used as long as they are defined in terms of network management.

  Since the 32-bit location code indicates a plurality of base stations in one area by bit positions, 32 base stations can be arranged in each area. When the base station is installed, an area code and a base station identifier (BSID) unique to the area are set for each base station. The value indicated by this BSID corresponds to the bit position in the location code. FIG. 3 shows an example of setting a multicast address. As for the multicast address, “1” is set in the bit position corresponding to the base station that needs to be transferred, and FIG. 3 shows a multicast address in which area 1, BSID # 1, and BSID # 2 are grouped as an example. In the area code, the value '1' indicating area 1 is shown, while in the location code, the bit positions (in this case, bit 1 and bit 2) indicating BSID # 1 and BSID # 2 are set to 1, Otherwise, 0 is assumed.

  By using such an address, when a frame addressed to a mobile terminal is mapped to a multicast address in a connecting station, a corresponding area code and a location code generated from a BSID which is necessary location information are held. It is not necessary to search for the multicast address actually set from the area code and the location code. This eliminates the need for a multicast address management table that is required in connection stations of the prior art. Also, the transfer table in the connecting station does not need to be mapped as shown in FIG.

  FIG. 4 shows an example of a transfer table in the connection station of the present invention. A paging area and location information (Location @) are managed for each of the mobile terminals MH # 1 and MH # 2. In the present invention, an area code and a location code are used for the paging area and location information, respectively. The location code for managing the location information indicates a base station from which the corresponding MH requests frame transfer, and each bit of the code indicates a base station identifier (BSID). In the example of FIG. 4, the mobile terminal MH # 2 indicates that the base station of BSID # 2 and BSID # 3 is requesting frame transmission. Also, MH # x whose location information is all 0 is in area # 2, but it is not clear which base station is under control, indicating that it is in an idle state.

  In order to use a multicast address, the base station mapped to the corresponding bit knows which base station to set up the address of the combination and sends a group join message to join the multicast group. Therefore, it is necessary to set up a corresponding multicast path in the network. Hereinafter, the operation of the base station according to the present invention will be described.

  Each base station uses an area code and BSID that are set in advance at the time of startup, to a group of multicast addresses configured using a location code that includes only itself, and a group of multicast addresses that do not have all location codes set Send a join message. All base stations join these two groups at start-up, so that multicast is set up in the same area for forwarding only to itself, and multicast is set up for all base stations in the same area. It will be.

Next, a multicast group setting procedure for transmitting data to a plurality of base stations used at the time of handover will be described.
FIG. 5 shows a schematic diagram and a sequence showing the operation in the network. FIG. 5 (a) shows the sequence of the network shown in FIG. 5 (b). This network relays between the connecting station (MAP) 1 and the base stations BS1 to BS3 and between the connecting station 1 and the base stations BS1 to BS3. This indicates that the mobile terminal MH is currently communicating with the base station BS2 and moves under the base station BS1 having the same area code as the base station BS2. The mobile terminal MH uses the area code and BSID included in the beacons from the base stations BS1 and BS2 to the base station BS2 that is currently communicating with the area code and BSID of the base station (BS1 in this case) as the handover destination. A soft handover request including is transmitted (step S1).

  The base station BS2 that has received this performs a decision process 1. Specifically, this will be described with reference to the flowchart shown in FIG. When the soft handover request is received (step S11), it is determined using the area code whether the area of the destination BS is the same (step S12). If the area codes are the same (yes in step S12), it is confirmed whether or not participation in the multicast group using the corresponding BSID and its own BSID has already been performed (step S13), and a message to join the group is transmitted. If not (No in step S13), a multicast address to be joined is generated from the corresponding area code and BSID, and signaling for joining this group is performed (step S14, step S3 → step S4 in FIG. 5). Here, GMRP (GARP Multicast Registration Protocol), which is an IEEE standard protocol for group participation, is used. This message is transmitted to the entire network via the relay station 2 in the middle (step S5, step S6-1, step S6-2, step S6-3 in FIG. 5). With this participation message, the base station BS2 that is in communication before moving joins the multicast group.

  Whether or not to participate in the multicast group, mapping of the destination BS information and the corresponding mobile terminal MH is performed on the connecting station 1 in order to update the location of the mobile terminal MH (mobile node MN). Notification is made (step S15 in FIG. 6). As a result, the connecting station 1 knows that the mobile terminal MH is requesting transmission to the base stations BS2 and BS1, and performs multicasting to a plurality of base stations by transmitting user data to be described later.

  On the other hand, the base stations BS1 and BS3 perform the determination process 2 shown in FIG. 5 when receiving the participation message transmitted by the base station BS2. Specifically, this will be described with reference to the flowchart shown in FIG. The base station that has received the group participation message checks whether or not it has already joined the same group (step S21 → step S22). If not, whether the area code included in the corresponding group address is the same. Confirmation is made (step S22 → step S23). If the area codes are the same, it is checked whether or not the BSID part of the own code is set in the location code (step S23 → step S24). If the area code is different (No in step S23) or if the BSID is not set (No in step S24), the process is terminated (step S28).

  When the own BSID is set (Yes in step S24), it is further confirmed whether there is any other BSID set (step S25). If it is also set in another BSID, this indicates that the group is a group for transmitting a frame to a plurality of base stations, and a participation message for the corresponding multicast is output and the process ends (steps S25 → S26). → S28).

If only its own BSID is set, this indicates an error. Normally, a multicast participation message output by itself is not received, and is not transmitted from a connected relay station (bridge) unless another base station outputs it. This indicates that another base station is misconfigured or that base stations having the same BSID exist in the same area. Therefore, in this case, not all location codes are set, and an error message is output to the multicast address using the area code to which it belongs, and the process ends (steps S25 → S27 → S28). Since all base stations participate in this multicast address at the time of start-up, error processing can be performed by this error message.
Through the processing as described above, the base station BS1 joins the multicast group including the base stations BS1 and BS2 and receives the corresponding multicast transmitted from the connection station 1. On the other hand, the base station BS3 does nothing since the group address in the received participation message is not an address indicating its own BSID (step S9 in FIG. 5).

  In this way, since the base station is mapped to the multicast address indicating the group, the standard group management is performed without managing the multicast group and the address to which group to join in the combination of which base station. It is possible to configure a necessary multicast group autonomously using a protocol. When the area code of the BSID notified from the mobile terminal MH is different, a soft handover request is simply transmitted to the connecting station 1.

Next, the operation of the connecting station will be described. When receiving the user data from the external IP network, the connecting station must appropriately transmit the data to the base station to which the mobile terminal is currently connected. Specifically, the user is identified from the received data, the location of the mobile terminal is grasped from the forwarding table, an appropriate destination address for the forwarding destination base station is generated, the frame is reconstructed and transmitted. In the present invention, since the forwarding table has the configuration shown in FIG. 4, the destination address may be a multicast address generated from the area code and location code shown in the forwarding table. Since all base stations participate in multicast with only themselves as members of the group at startup, the multicast address is generated using the location code as it is, regardless of whether there is one base station or multiple base stations. Just do it.
The operation at the connecting station will be described.
1) Search user data and generate an address.
2) Always generate a multicast address from the forwarding table.
3) If all 0s, paging is performed.

  Also, in mobile communications such as mobile phones, mobile terminals do not always update the base station to which they are connected in order to reduce battery consumption. It often has a mode (dormant mode). In this case, an area is provided for indicating the approximate location of the mobile terminal when an incoming call is received. Paging is performed in order to grasp the detailed position of the base station for this area. However, in the present invention, since the area code already exists in the multicast address, paging for this area may be performed. In paging, since it is necessary to transmit a frame to all base stations in the corresponding area, only an area code is set, and an address whose location code is all 0 is set. That is, in a mobile terminal that has become idle in the connection station 1, all the location codes may be set to 0 in the transfer table to indicate that there is no base station to connect to. Further, when the area is moved at the time of idling, it is only necessary to request the connection station 1 to update only the area code as a location update. By using such a forwarding table, the header of the frame can be configured using the forwarding table code as it is regardless of the state of the mobile terminal.

<Base station unicast address generation method>
Next, as Embodiment 2, the case where the unicast address of the base station is used in the present invention will be described. In the present invention, each base station has a BSID uniquely set in the area. For this reason, the multicast address generated from the area code and its own BSID is unique within the corresponding local network. Therefore, by inverting the head unicast / multicast (U / M) bit, a unique unicast address can be generated in the local network. This address is shown in FIG. As described in “Background Art”, in the case of a system that supports mobility on a network basis, a connecting station is required to transfer a frame to a base station to which a corresponding mobile terminal is actually connected. For this reason, when the access network is configured by an L2 network, the L2 address of the corresponding base station is used. For this reason, the base station generates and sets a unicast address of its connected station side interface from the area code and the set BSID at the time of activation.

  FIG. 2 shows, as an example, local unicast addresses in area 1 and BSID # 1. As a result, if there is only one bit set to 1 in the location code from the position information in the transfer table held by the connecting station, the correct base station can be obtained by simply changing the bit used for transfer from multicast to unicast. It is possible to transmit a unicast frame. In normal bridge transfer, the load of unicast transfer is lower than the transfer of multicast frame. Therefore, the load on the network can be reduced without increasing the load of address management. Further, this unicast address is used as a transmission source address when a frame is transmitted from the base station regardless of which mobile terminal the frame is forwarded to, so the possibility of flooding is low.

  Note that each functional block such as an address generation unit used in the description of the embodiment of the present invention is typically realized as an LSI (Large Scale Integration) which is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Here, although LSI is used, it may be called IC (Integrated Circuit), system LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used. Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. For example, biotechnology can be applied.

  The present invention has the effect of reducing the processing load on the connecting station, and can be used for soft handover control by L2 multicast.

Explanatory drawing which shows the structure of the address which concerns on this invention Explanatory drawing which shows an example of a structure of the unicast address which concerns on this invention Explanatory drawing which shows an example of the structure of the multicast address which concerns on this invention Explanatory drawing which shows an example of the transfer table which concerns on this invention It is explanatory drawing which shows the communication sequence and network which concern on this invention, (a) is explanatory drawing which shows a communication sequence, (b) is explanatory drawing which shows a network. The flowchart which shows the setting judgment 1 of FIG. 5 in detail The flowchart which shows the setting judgment 2 of FIG. 5 in detail Explanatory diagram showing a conventional network It is explanatory drawing which shows the mapping management table of the conventional multicast address, (a) is explanatory drawing which shows a response | compatibility with the combination of a base station, and a multicast address, (b) is explanatory drawing which shows a response | compatibility with a paging area and a multicast address. Explanatory drawing showing a conventional forwarding table It is explanatory drawing which shows the conventional communication sequence and a network, (a) is explanatory drawing which shows a communication sequence, (b) is explanatory drawing which shows a network.

Explanation of symbols

1 Connected station (MAP)
2, 3 Relay station (Bridge)
MH # 1, MH # 2 mobile terminals BS1 to BS5 radio base stations

Claims (17)

In an access network having a connection station connected to an external IP network and a plurality of radio base stations to which a mobile terminal is connected, when the mobile terminal performs handover between two radio base stations, the mobile terminal A handover control method for transferring an IP packet addressed to the plurality of radio base stations,
The connecting station generates a location code indicating a wireless base station to which a packet is to be transferred for each mobile terminal based on a value of a corresponding bit with each identifier value assigned to the wireless base station as a bit position. A handover control method comprising: generating and transmitting a destination address including   The handover control method according to claim 1, wherein the generated destination address is always a multicast address.   The handover control method according to claim 1, wherein the destination address to be generated is a unicast address when only one bit is set in the location code.   When no bit is set in the location code of the destination mobile terminal when receiving a packet from the external IP network, the connecting station generates a multicast address using the location code and uses this address to 2. The handover control method according to claim 1, wherein paging processing for searching for a radio base station to which the mobile terminal is connected is performed. The access network constitutes an area for grouping the plurality of radio base stations into a plurality of groups,
The handover control method according to claim 1, wherein the generated destination address includes an area code indicating this area together with a location code.   When the currently connected mobile terminal is handed over, the radio base station notifies the identifier of the destination base station using the identifier value of the destination base station and its own base station. The location code of which position is set is generated, a multicast address group is generated using the location code, and a group join message indicating participation in the multicast address group is output. Handover control method. The mobile terminal has a plurality of radio base stations to which the mobile terminal is connected, and when the mobile terminal performs handover between two radio base stations, an IP packet addressed to the mobile terminal from an external IP network is transferred to the plurality of radio base stations. A connecting station that can be controlled to transfer and belongs to an access network and is connected to the external IP network,
Location code generating means for generating a location code indicating a wireless base station that is a packet transfer destination for each mobile terminal, based on the value of the corresponding bit with the value of each identifier assigned to the wireless base station as a bit position;
Address generating means for generating and transmitting a destination address including the location code;
Connected station provided.   8. The connection station according to claim 7, wherein the address generation means always generates a multicast address.   The connecting station according to claim 7, wherein the address generating means generates a unicast address when only one bit is set in the location code. The address generation means generates a multicast address using the location code when no bit is set in the location code of the destination mobile terminal when receiving a packet from the external IP network;
Paging processing means for performing paging processing for searching for a radio base station to which the mobile terminal is connected using the multicast address;
The connection station according to claim 7, further comprising: The access network constitutes an area for grouping the plurality of radio base stations into a plurality of groups,
8. The connection station according to claim 7, wherein the address generation unit generates a destination address including an area code indicating the area together with a location code. A wireless base station that belongs to an access network having a connection station that connects to an external IP network and that a mobile terminal connects to,
When the currently connected mobile terminal is handed over, the location where the corresponding bit position is set using the identifier value of the destination base station and its own base station when the identifier of the destination base station is notified Location code generation means for generating code;
A group participation message output means for generating a multicast address group using the location code and outputting a group participation message indicating participation in the multicast address group;
Having a radio base station. When receiving the group participation message, a group participation determination means for determining whether or not to participate in the group of the received participation message,
The radio base station according to claim 12, further comprising:   The group participation determination means, when each bit of the location code included in the group address is set with the bit at the bit position indicated by the value of its own identifier, and when one or more other bits are set The wireless base station according to claim 13, wherein participation processing for the corresponding group is executed.   The group participation determination means, when each bit of the location code included in the group address is set to the bit at the bit position indicated by the value of its own identifier, and other bits are not set, an error message The radio base station according to claim 13, wherein the radio base station is transmitted using a destination multicast address using a location code in which no bit is set.   The group participation determination means executes a process of joining a multicast address group generated using a location code in which only the bit position of the value of the corresponding identifier is set from the identifier set to itself at startup. The radio base station according to claim 13. The group participation determination means generates a unicast address using a location code in which only the bit position of the value of the corresponding identifier is set from the identifier set to itself at the time of activation, and sets this as its own unicast address The radio base station according to claim 13.