JP4588365B2 - Edge node and mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system between different types of radio access systems that can be switched to another available radio access mode among a plurality of different radio access mode network systems, and an edge node used therefor.

  Conventionally, many wireless systems (IEEE802.11b, 11a, 11g, 3G cellular, PHS) including wired and cellular systems exist. Currently, new wireless systems are being studied and standardized. Each of these communication systems has different characteristics. For example, since there are differences in the maximum communication speed, communication area, movement characteristics, etc., it is considered that each communication system will be divided according to the purpose and area. Under such circumstances, in recent years, mobile terminals having a communication function with a plurality of wired / wireless systems have appeared, and it is possible to select these communication systems according to the purpose and situation.

  In addition, as a function for supporting the movement of a terminal, specifications of a mobile IP (Internet Protocol) protocol are currently being defined (for example, see Non-Patent Document 1). With the mobile IP, even if the terminal moves and is connected to another network, it is possible to continue communication by using the IP address assigned to the terminal as it is. This IP address can be used even between different networks (heterogeneous media) configured by different communication systems.

Mobility Support in IPv6 "draft-ietf-mobileip-ipv6-24.txt" 02 Jul. 2003

  However, in such a handover between different types of media, the maximum (effective) link bandwidth between the terminal and the access point (Access Point) is different, so in the upper layer (application) of IP at the end-to-end There is a problem that bursty packet discard, excess delay, and delay jitter occur.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an edge node excellent in communication performance at the time of handover in a mobile communication system and a mobile communication system including the edge node.

In order to solve the above-described problems and achieve the object, the edge node according to the present invention includes a plurality of radio access networks that perform packet data communication using different radio access schemes having an access point, and other networks as a core network. An edge node used in a mobile communication system connected via a communication unit for transmitting and receiving packets to and from a core network and an access network, a mobile node notified from the access network and other edge nodes, and A network information management unit that manages and holds network information related to an access point, a handover target determination unit that determines whether a destination of a packet received by the communication unit is addressed to a mobile node after handover, and a handover target determination unit At destination Compare the link bandwidth of the access point before and after the handover of the mobile node held by the network information management unit or the effective link bandwidth of the mobile node for packets determined to be addressed to the mobile node after the handover In the comparison between the bandwidth comparison unit and the bandwidth comparison unit, the link bandwidth of the access point after handover or the effective link bandwidth of the mobile node is equal to the bandwidth of the access point before handover or the effective link bandwidth of the mobile node. The upper layer analysis unit that analyzes the upper layer of the packet received by the communication unit to determine whether the packet is a TCP packet, an RTP packet, or another packet, and the packet received by the reception unit If it is a TCP packet, the packet And discarding processing unit that performs disposal processing, if the packet received by the receiving portion is an RTP packet, and a shaping unit that performs shaping of transmitting the packet at a predetermined constant rate, discarding processing unit The link bandwidth of the access point where the mobile node before the handover is accommodated or the effective link bandwidth of the mobile node, and the bandwidth of the access point where the mobile node is accommodated after the handover or the effective link of the mobile node The TCP packet discard rate is varied in accordance with the link bandwidth ratio with the bandwidth .

  According to the present invention, the edge node holds network information related to the mobile node and the access point before and after the handover, and packet handling, that is, packet processing is appropriately changed using the network information.

  According to the present invention, the edge node holds the network information about the mobile node and the access point before and after the handover, and appropriately changes the handling of the IP packet using the network information. By performing traffic control, network congestion can be avoided / mitigated, bursty packet discard, excess delay, and delay jitter can be prevented as in congestion, and communication performance during handover can be improved. Therefore, according to the present invention, it is possible to obtain an edge node having excellent communication performance during handover in a mobile communication system.

  Exemplary embodiments of an edge node and a mobile communication system having the edge node according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a schematic configuration of a mobile communication system between different types of radio systems according to the first embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of the main part of the packet transfer apparatus which is an edge node according to the present invention. FIG. 1 shows an example of a mobile communication system between different types of radio systems when two different types of radio access schemes are applied. In this system, a wireless LAN (Wireless LAN: WLAN 11a, 11b, 11g, etc.) communication system and a 3rd Generation (3G) communication system are applied as communication systems using different wireless access methods. .

  As shown in FIG. 1, a mobile communication system according to the present embodiment includes a mobile node (MN) 2, a wireless LAN access point (AP) 4, a 3G access point 8, an access network. (Access Network) 12, edge node (Edge Node) 14, core network (Core Network) 16, edge node (Edge Node) 18, and correspondent node (CN: Correspondent Node) 20, Have built.

  Here, the mobile node 2 is a mobile terminal that performs handover. The wireless LAN access point 4 and the 3G access point 8 are connection points for accessing various communication systems such as a wireless LAN (11a, 11b, 11g, etc.) base station, a 3G base station, and a wired communication system. The edge nodes 12 and 18 are packet transfer apparatuses according to the present embodiment. The access network 12 is an IP network that connects the WLAN access point 4 and the 3G access point 8 and the edge node 12. The core network 16 is an IP network that connects access networks in each area. The correspondent node 20 is a communication partner of the mobile node 2. There is no problem even if the correspondent node 20 is a mobile terminal.

  In FIG. 1, dotted line arrows 22 indicate network information (number of access points in the downstream access network, area, maximum link bandwidth, number of terminals (mobile nodes) connected to the access point, effective link bandwidth, Information such as terminal movement speed), and a solid arrow 26 indicates the flow of a traffic route.

  The wireless LAN communication system includes a wireless LAN access point 4 that performs wireless communication with the mobile node 2 using a wireless access method within a predetermined area (wireless LAN access point area 6). The wireless LAN access point 4 is connected to the edge node 14 via the access network 12.

  Similarly, the 3G communication system includes a 3G access point 8 that performs wireless communication with the mobile node 2 using the 3G method within a predetermined area (3G access point area 10). An access point 8 is connected to an edge node 14 via an access network 12.

  As shown in FIG. 2, the edge node 14 includes a first communication unit 101, a handover target determination unit 102, a band comparison unit 103, a higher layer analysis unit 104, a network information management unit 105, and a discard processing unit. 106, a shaping unit 107, and a second communication unit 108. Here, the first communication unit 101 has a function of performing data communication with the access network 12. The handover target determining unit 102 has a function of verifying and determining whether the destination of the received IP packet is addressed to the mobile node 2 after the handover. The bandwidth comparison unit 103 compares the maximum link bandwidth (or effective link bandwidth of the terminal) of the access point before and after movement held in the network information management unit 105 when the received IP packet is a handover target packet. It has the function to do.

  The upper layer analysis unit 104 has a function of analyzing the upper layer (TCP, RTP) of the received IP packet. The network information management unit 105 has a function of managing and holding network information notified from downstream access networks and other edge nodes. The discard processing unit 106 has a function of changing the discard characteristics based on network information for TCP packet handling. The shaping unit 107 has a function of sending data at a specified constant rate when sending data to a destination network for RTP packet handling. The second communication unit 108 has a function of performing data communication with the core network 16.

  Next, the operation of the mobile communication system according to the present embodiment constructed as described above will be described. First, a case where the mobile node 2 and the correspondent node 20 perform communication by IP will be described. When the mobile node 2 and the correspondent node 20 are communicating by IP in a wireless LAN communication system, the access point that accommodates the mobile node 2 that is in communication is connected to the upstream edge node. The network information is notified to the node. In FIG. 1, the wireless LAN access point (AP) 4 notifies network information via the access network 12 to the upstream edge node 14.

  This network information includes the maximum link bandwidth for the access point, area range, number of accommodated terminals, congestion state, effective link bandwidth for the terminal accommodated by the access point, traffic volume, moving speed, residence time, IP The address is included. Accordingly, in this case, the network information notified to the upstream edge node 14 by the wireless LAN access point (AP) 4 includes the maximum link bandwidth, the area range, and the accommodation terminal regarding the wireless LAN access point (AP) 4. Number, congestion status, and effective link bandwidth, traffic volume, moving speed, dwell time, and IP address for the mobile node 2 accommodated by the wireless LAN access point (AP) 4.

  The upstream edge node 14 manages and holds the network information notified from the wireless LAN access point (AP) 4 for each access point in the network information management unit 105.

  Next, the mobile node 2 moves from the range of the wireless LAN access point area 6 to the range of the 3G access point area 10 (in the direction of the dotted line 24 in FIG. 1), and the different access Switch to point and network (handover). In FIG. 1, the access point that accommodates the mobile node 2 is switched from the wireless LAN access point (AP) 4 to the 3G access point 8.

  In this case, the access point (moving destination access point) accommodating the moved mobile node 2 is the access point accommodating the mobile node 2 before moving (handover) (pre-moving access point). Similarly, the network information is notified to the upstream edge node 14. In FIG. 1, the destination access point is the 3G access point 8, and the pre-movement access point is the wireless LAN access point (AP) 4. Therefore, the 3G access point 8 that is the destination access point notifies the upstream edge node 14 of the network information.

  Here, the network information notified to the upstream edge node 14 by the 3G access point 8 which is the movement destination access point includes the same information as described above. Thereby, the upstream edge node 14 uses the network information of the access points before and after the movement (wireless LAN access point (AP) 4 and 3G access point 8) and the network information of the terminal (edge node 14) as the network information. It can be held and managed by the management unit 105. As the terminal identifier, for example, HoA (Home Address) and CoA (Care of Address) are used.

  Next, assuming that the edge node 14 receives an IP packet addressed to the mobile node 2 from the correspondent node 20 after the handover, the processing in this case will be described with reference to the flowchart shown in FIG.

  First, the edge node 14 receives an IP packet from the correspondent node 20 via the core network 16 in the same manner as a normal router (step S1). The edge node 14 determines a handover target. That is, the edge node 14 verifies whether or not the destination of the received IP packet is addressed to the mobile node after the handover (step S2). At this time, when the destination of the IP packet is not destined for the mobile node 2 after the handover (No at Step S2), the normal packet transfer is executed to the access network 12 according to the routing table (Step S5), and the process ends. To do.

  On the other hand, when the destination of the IP packet is addressed to the mobile node 2 after the handover (Yes at Step S2), that is, when the received IP packet is the handover target packet, the edge node 14 performs the following processing. Then, the maximum link bandwidth (or effective link bandwidth of the terminal) of the access point before and after the movement held in the network information management unit 105 is compared (step S3).

  Here, the maximum link bandwidth of the access point after movement (wireless LAN access point (AP) 4) (or the effective link bandwidth of the terminal) is larger than the link bandwidth of the access point before movement (3G access point 8). In this case (No at Step S3), the edge node 14 executes normal packet transfer to the access network 12 (Step S5), and the process ends. On the other hand, when the maximum link bandwidth (or effective link bandwidth of the terminal) of the access point after movement (wireless LAN access point (AP) 4) is smaller than the bandwidth of the access point before movement (3G access point 8). (Yes in step S3), the edge node 14 proceeds to the next process, and the upper layer analysis unit 104 analyzes the upper layer of the received IP packet, and the upper layer of the IP packet is other than TCP, RTP, TCP / RTP. An upper layer determination is performed to determine whether the other is (step S4).

  In the upper layer determination, when the upper layer of the received IP packet is other than TCP / RTP, the edge node 14 performs normal packet transfer to the access network 12 (step S5), and the process is terminated. . Note that the protocol number in the IPv4 header and the Next Header value in the IPv6 header are used as the upper layer determination, but the ToS (IPv4) or Traffic Class (IPv6) field in the IP header is used (mapped) as an identifier. Is also possible.

  In the upper layer determination, when the upper layer of the received IP packet is TCP, the edge node 14 executes the discard processing of the IP packet in the discard processing unit 106 (step S6), and the processing is ended. In the upper layer determination, if the upper layer of the received IP packet is RTP, the edge node 14 executes the shaping process in the shaping unit 107 and transfers the packet to the access network 12 (step S7). ), The process ends.

  FIG. 4 is a characteristic diagram showing a packet discard characteristic in the discard process of the IP packet in the discard processing unit 106 when the upper layer of the received IP packet is TCP. The image of the packet discard characteristic here is RED (Random Early Detection), and the horizontal axis is the maximum link bandwidth ratio of the access points before and after the handover, and the IP packet is stochastically discarded according to the link bandwidth ratio.

  Further, the link bandwidth ratio before and after handover held by the network information management unit 105 and the buffer management algorithm in the discard processing unit 106 are combined to reduce the discard rate by the residence time after handover as shown in FIG. It is possible to determine the expected congestion state immediately after the handover according to the bandwidth ratio, and to change the IP packet discard rate. By discarding IP packets at the edge node 14 in advance for traffic expected to be discarded at the access point after handover, it is possible to prevent excessive traffic from flowing into the access network 12. As a result, bursty packet discard, excess delay, and delay jitter can be prevented as in congestion.

  Furthermore, when the total number of traffic exceeds the allowable traffic by changing the discard rate of the IP packet in consideration of the number of terminals accommodated in the access point after handover and the communication traffic of the terminals downstream of the edge node. Can change the IP packet discard rate to be high so that the traffic of all terminals is substantially equal. Further, the discard rate can be changed in consideration of the moving speed of the mobile node number 2 and the communication area of the access point. Further, when the reachability to the terminal is low, the discard rate is changed to be high. As described above, by filtering IP packets at the edge node 14, it is possible to prevent excessive traffic from flowing into the access network 12, and to avoid / mitigate congestion.

  FIG. 5 is a diagram for explaining the shaping process when the upper layer of the received IP packet is RTP. As shown in FIG. 5, when the link bandwidth after handover held by the network information management unit 105 is smaller than the link bandwidth before handover and the upper layer of the received IP packet is RTP, access after handover is performed. A shaping process (rate control process) that matches the link bandwidth of the point is executed.

  By performing such processing, bursty IP packet discarding can be prevented and adverse effects on applications such as streaming can be avoided. In addition, it is possible to quickly reduce excessive traffic that is discarded due to excess of the maximum link bandwidth at the access point after handover. Also, traffic control can be performed without managing each RTP flow by collecting and shaping the flows for each downstream access point.

  An example of the shaping process will be described with reference to FIG. FIG. 5 shows a case where the edge node 14 has a distribution unit 109 that distributes the IP packet 30 from the upper layer analysis unit 104 according to a predetermined reference as an example. Processing in this case will be described with reference to FIG. In FIG. 5, dotted arrows indicate the flow of network information, and solid arrows indicate the flow of IP packets.

  First, the distribution unit 109 receives the IP packet 30 from the higher layer analysis unit 104 (step S21). Next, the distribution unit 109 collects network information from the network information management unit 105 (step S22), and distributes the IP packet 30 based on the network information and communication conditions set in advance in the IP packet (step S22). S23). In FIG. 5, the IP packets 30 are sorted using a communication speed set in advance for the IP packet service type. Then, the distributed IP packet 30 is sent to the shaping unit 107 in a predetermined distribution unit, and a shaping process is executed (step S24).

  Further, by combining the discard rate control as shown in FIG. 4 and the shaping process as shown in FIG. 5, the packet corresponding to the required specification (priority) set in the terminal (mobile node 2). It is also possible to handle.

  As described above, in the present embodiment, the edge node holds network information related to the terminal (mobile node) and the access point before and after the handover, and appropriately changes the handling of the IP packet using the network information. By doing so, network handling can be avoided and alleviated by performing packet handling and traffic control according to higher layers, so that bursty packet discard, excess delay, and delay jitter are prevented as in congestion. The communication performance at the time of handover can be improved.

Embodiment 2. FIG.
FIG. 7 is a diagram showing a schematic configuration of a mobile communication system between different types of radio systems according to the second embodiment of the present invention. In the first embodiment, the case where the upstream edge node of each access point at the time of handover is the same edge node has been described. However, in this embodiment, the case where the upstream edge node at the time of handover is different will be described. . 7, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted here. Therefore, here, differences between the mobile communication system between different types of radio systems according to the present embodiment and the mobile communication system between different types of radio systems according to the first embodiment will be described.

  The mobile communication system between the different types of radio systems according to the present embodiment is different from the mobile communication system between the different types of radio systems according to the first embodiment, because different access networks and edge nodes are located upstream of different access points. Is provided. That is, the mobile communication system according to the present embodiment includes a mobile node (MN) 2, a wireless LAN access point (AP) 4, a 3G access point 8, as shown in FIG. An access network (Access Network) 40, an access network (Access Network) 42, an edge node (Edge Node) 44, an edge node (Edge Node) 46, a core network (Core Network) 16, and an edge node (Edge Node) 18 and a Correspondent Node (CN) 20 are constructed.

  Here, the edge nodes 44 and 46 have the same functions as the edge node 14 in the first embodiment. The access network 40 is an IP network that connects the WLAN access point 4 and the edge node 44. The access network 42 is an IP network that connects the 3G access point 8 and the edge node 46.

  In addition, in the wireless LAN communication system according to the present embodiment, a wireless LAN access point that performs wireless communication with the mobile node 2 using a wireless access method within a predetermined area (wireless LAN access point area 6). The wireless LAN access point 4 is connected to the edge node 44 via the access network 40.

  Similarly, the 3G communication system includes a 3G access point 8 that performs wireless communication with the mobile node 2 using the 3G method within a predetermined area (3G access point area 10). The access point 8 is connected to the edge node 46 via the access network 42.

  In FIG. 7, dotted line arrows 22 indicate network information (number of access points in the downstream access network, area, maximum link bandwidth and the number of terminals connected to the access point, effective link bandwidth, terminal movement speed, etc. Information flow), and solid arrows indicate traffic flow.

  Next, the operation of the mobile communication system according to the present embodiment constructed as described above will be described with reference to FIG. FIG. 8 is a flowchart showing a part of the operation of the mobile communication system when the mobile node 2 is handed over to a different access point by the upstream edge node. First, a case where the mobile node 2 and the correspondent node 20 are communicating by IP will be described. When the mobile node 2 and the correspondent node 20 are communicating by IP in a wireless LAN communication system, the access point that accommodates the mobile node 2 that is in communication is connected to the upstream edge node. The network information is notified to the node. In FIG. 7, the wireless LAN access point (AP) 4 notifies network information to the edge node 44 located upstream via the access network 40.

  This network information includes the maximum link bandwidth for the access point, area range, number of accommodated terminals, congestion state, effective link bandwidth for the terminal accommodated by the access point, traffic volume, moving speed, residence time, IP The address is included. Accordingly, in this case, the network information notified to the upstream edge node 44 by the wireless LAN access point (AP) 4 includes the maximum link bandwidth, the area range, and the accommodation terminal regarding the wireless LAN access point (AP) 4. Number, congestion status, and effective link bandwidth, traffic volume, moving speed, dwell time, and IP address for the mobile node 2 accommodated by the wireless LAN access point (AP) 4.

  Next, the mobile node 2 moves from the range of the wireless LAN access point area 6 to the range of the 3G access point area 10 (in the direction of the dotted line 24 in FIG. 7), The edge node is switched to a different access point and network (handover, step S41)). In FIG. 1, the access point that accommodates the mobile node 2 is the wireless LAN access point (AP) 4 whose upstream edge node is the edge node 44, and the upstream node is the edge node 46. Switch to G access point 8.

  At this time, the access point (moving destination access point) accommodating the moved mobile node 2 is moved to the access point (pre-moving access point) accommodating the mobile node 2 before moving (handed over). Similarly, the network information is notified to the upstream edge node. In this case, the destination access point notifies the network information not to the edge node to which the pre-movement access point has notified the network information, but to the upstream edge node of itself (step S42). In FIG. 7, the destination access point is the 3G access point 8, and the pre-movement access point is the wireless LAN access point (AP) 4. Therefore, the 3G access point 8 which is the movement destination access point notifies the upstream edge node 46 of the network information.

  In this way, the upstream edge node 46 of the destination access point is notified of the network information, so that the edge node 46 is not under the management of its downstream downstream access point by the mobile node 2, Recognize that there is no network information before moving. Then, in the destination edge node 46 of the mobile node 2, an inquiry is made as to whether or not the network information management unit 105 holds network information related to the terminal handed over to the adjacent edge node and the pre-movement access point. Is executed (step S43). In this case, the inquiry is made by the network information management unit 105, but it is also possible to have a dedicated network information collecting means, and the means can perform the above processing.

  The adjacent edge node that has received this inquiry searches the network management unit 105 for a designated terminal. When the history of the target terminal is found in the network management unit 105, the network information management unit 105 of the adjacent edge node returns the network information regarding the handed over terminal and the pre-movement access point as an edge node as a response to the inquiry. 46 is notified. If the history of the target terminal is not found in the network management unit, the network information management unit 105 of the adjacent edge node notifies the edge node 46 that the network information is not held as a response to the inquiry. (Step S44). The above processing is also performed by the network information management unit 105, but it is also possible to have a dedicated unit that can perform the above processing.

  As a result, the upstream edge node 46 after the mobile node 2 has moved moves the network information of the access point and the network information of the terminal before and after the movement into the network information management unit 105 as in the first embodiment. Can be maintained and managed. Thereafter, the same operation as in the first embodiment (see the flowchart in FIG. 3) is performed.

  As described above, in the present embodiment, even when the upstream edge node performs different handover, the upstream edge node 46 to which the mobile node 2 moves is based on the network information before and after the movement. It is possible to control excessive traffic to 12 and avoid / mitigate network congestion.

Embodiment 3 FIG.
In the third embodiment, a mobile communication system between different types of radio systems in which an edge node can predict whether or not a mobile node is handed over and an access point to which the mobile node is handed over will be described. Since the network configuration in the present embodiment is the same as that in the second embodiment described above, detailed description will be omitted with reference to FIG. 7 and the description in the second embodiment. The edge node holds the function described in the first embodiment. Therefore, the detailed description is omitted by referring to the description in FIG. 3 and the first embodiment. Below, operation | movement of the mobile communication system concerning this Embodiment is demonstrated using FIG. FIG. 9 is a flowchart showing a part of the operation of the mobile communication system in which the edge node can predict the presence / absence of handover of the mobile node and the access point to which the mobile node is handed over.

  First, a case where the mobile node 2 and the correspondent node 20 perform communication by IP will be described. When the mobile node 2 and the correspondent node 20 are communicating by IP in a wireless LAN communication system, the access point that accommodates the mobile node 2 that is in communication is connected to the upstream edge node. The network information is notified to the node. In FIG. 7, the wireless LAN access point (AP) 4 notifies the edge node 14 upstream of the network information via the access network 12.

  Next, the edge node 14 predicts the presence / absence of handover of the mobile node 2 and the handover destination access point. Here, the presence / absence of handover of the mobile node 2 and the prediction of the access point to which the mobile node 2 is handed over, for example, the wireless LAN access point (AP) 4 predicts the access point to which the mobile node 2 is handed over. And a movement predicting unit 109 that predicts the presence / absence of movement (handover) of the mobile node and the movement (handover) destination as shown in FIG. be able to.

  That is, the wireless LAN access point (AP) 4 first detects the position of the mobile node 2 at a predetermined time interval by the position detection unit (step S61). Then, the wireless LAN access point (AP) 4 notifies the edge node 14 of the detected position detection result of the mobile node 2 together with the network information described above (step S62). In the edge node 14, the movement prediction unit 109 stores the position detection result of the mobile node 2, and based on the past detection position and the latest detection position, the presence / absence of handover of the mobile node 2 and the future mobile node Predict the area where node 2 will move and the access point that will accommodate mobile node 2 in that area. Then, by predicting the access point, it is possible to predict the edge node upstream of the access point in which the moved mobile node 2 is accommodated (step S63).

  In this case, the position detection unit does not require a particularly high detection accuracy, and has an accuracy that can detect the position of the mobile node 2 at a predetermined interval and specify the direction in which the mobile node 2 moves. It should be. In addition, the presence or absence of the handover of the mobile node 2 and the method of predicting the access point of the handover destination of the mobile node 2 are not limited to this, and various methods can be used.

  In the present embodiment, by performing the above processing, the edge node 44 predicts that the mobile node 2 will be handed over. Then, the edge node 44 predicts that the area where the mobile node 2 will move is the 3G access point area 10 and the access point that accommodates the mobile node 2 in this area is the 3G access point 8. . Thereby, the edge node 44 can predict that the edge node upstream of the access point in which the mobile node 2 after movement is accommodated is the edge node 46.

  Next, the edge node 44 that is the upstream edge node before the movement notifies the edge node 46 that is the predicted upstream edge node of the movement destination in advance (step S64). Then, after the mobile node 2 is handed over, the 3G access point 8 that is the destination access point accommodating the destination mobile node 2 notifies the upstream edge node 46 of the network information ( Step S65). As a result, the upstream edge node 46 transmits the network information of the access point and the network information of the terminal before and after the movement of the mobile node 2 in the same manner as in the first and second embodiments described above. It can be held and managed at 105. Thereafter, the same operation as in the first embodiment (see the flowchart in FIG. 3) is performed.

  As described above, in the present embodiment, even immediately after a handover, the upstream edge node of the destination can control excessive traffic to the access network based on the network information before and after the movement, and avoid or alleviate network congestion. Is possible. Further, the discard processing unit 106 is configured to predict the link bandwidth of the access point after the handover of the mobile node of the destination to be moved or the effective link bandwidth of the mobile node and the access point in which the mobile node before the handover is accommodated. The discard rate of TCP packets can be varied according to the link bandwidth ratio with the bandwidth or the effective link bandwidth of the mobile node. Further, the discard processing unit 106 predicts a congestion state (queue length) in the mobile node 2 from the link bandwidth ratio, and a TCP packet according to the congestion state that causes the discard rate in the discard processing unit to fluctuate highly at the time of congestion. The discard rate can be varied.

  Further, the discard processing unit 106 can change the discard rate of TCP packets according to the predicted number of mobile nodes accommodated in the mobile node 2 and the traffic amount of the mobile node. By performing such an operation, congestion due to handover can be effectively reduced. Furthermore, considering the number of accommodated terminals in the predicted edge node of the destination and the actual traffic of each terminal, if the traffic of all terminals exceeds the allowable traffic after the handover, It is possible to vary the discard rate high so that the traffic volume of the nodes is substantially equal. By performing the above operations, congestion due to handover can be effectively reduced.

Embodiment 4 FIG.
FIG. 11: is a figure which shows schematic structure of the mobile communication system between the heterogeneous radio systems concerning Embodiment 4 of this invention. In the first embodiment, the handover control of the IP packet sent from the correspondent node 20 to the core network 16 has been described. However, in this embodiment, the IP flowing from the correspondent node 20 to the core network 16 is described. Packet handover control will be described. 11, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted here. Therefore, here, differences between the mobile communication system between different types of radio systems according to the present embodiment and the mobile communication system between different types of radio systems according to the first embodiment will be described.

  As shown in FIG. 11, the mobile communication system according to the present embodiment includes a mobile node (MN) 2, a wireless LAN access point (AP) 4, a 3G access point 8, and an access network. (Access Network) 12, edge node (Edge Node) 14, core network (Core Network) 16, edge node (Edge Node) 48, and correspondent node (CN: Correspondent Node) 20, Have built.

  The edge node 48 in the present embodiment retains the functions described in the first and second embodiments, but further manages information on the correspondent node 20 that is communicating with the mobile node 2 in the network information management unit 105. To do. In the present embodiment, the first communication unit 101 has a function of performing data communication with the correspondent node 20. In the present embodiment, the second communication unit 108 has a function of performing data communication with the core network 16.

  Next, the operation of the mobile communication system according to the present embodiment constructed as described above will be described. First, a case where the mobile node 2 and the correspondent node 20 perform communication by IP will be described. When the mobile node 2 and the correspondent node 20 are communicating by IP in a wireless LAN communication system, the access point that accommodates the mobile node 2 that is in communication is connected to the upstream edge node. The network information is notified to the node. In FIG. 11, the wireless LAN access point (AP) 4 notifies the edge node 14 upstream of the network information via the access network 12.

  The upstream edge node 14 manages and holds the network information notified from the wireless LAN access point (AP) 4 for each access point in the network information management unit 105.

  Next, the mobile node 2 moves from the range of the wireless LAN access point area 6 to the range of the 3G access point area 10 (in the direction of the dotted line 24 in FIG. 11), and the different access Switch to point and network (handover). In FIG. 11, the access point that accommodates the mobile node 2 is switched from the wireless LAN access point (AP) 4 to the 3G access point 8.

  In this case, the access point (moving destination access point) accommodating the moved mobile node 2 is the access point accommodating the mobile node 2 before moving (handover) (pre-moving access point). Similarly, the network information is notified to the upstream edge node 14. In FIG. 11, the destination access point is the 3G access point 8, and the pre-movement access point is the wireless LAN access point (AP) 4. Therefore, the 3G access point 8 that is the destination access point notifies the upstream edge node 14 of the network information.

  Here, the network information notified to the upstream edge node 14 by the 3G access point 8 which is the movement destination access point includes the same information as described above. Thereby, the upstream edge node 14 uses the network information of the access points before and after the movement (wireless LAN access point (AP) 4 and 3G access point 8) and the network information of the terminal (edge node 14) as the network information. It can be held and managed by the management unit 105. As the terminal identifier, for example, HoA (Home Address) and CoA (Care of Address) are used.

  Then, the edge node 14 upstream of the access point notifies the network information to the edge node 48 upstream of the correspondent node 20 communicating with the mobile node 2. As a result, the edge node 48 upstream of the correspondent node 20 allows the network information of the access points before and after movement (wireless LAN access point (AP) 4 and 3G access point 8) and the network of the terminal (edge node 14). Information can be held and managed in the network information management unit 105. Further, the network information management unit 105 receives notification of network information from the correspondent node 20, and holds and manages this.

  Here, assuming that the edge node 48 receives an IP packet addressed to the mobile node 2 from the correspondent node 20 after the handover, the edge node 48 replaces the edge node 14 with the edge node 48. In the first embodiment, except that the edge node 48 receives an IP packet from the correspondent node 20 and that the forwarding destination of the IP packet at the edge node 48 is not the access network 12 but the core network 16. The process described with reference to FIG. 3 is performed.

  As described above, in the present embodiment, it is possible to control excessive traffic before the edge node flows into the core network, and to avoid / mitigate network congestion in the core network.

  As described above, the edge node according to the present invention is useful for a mobile communication system that performs packet data communication using a radio access scheme, and in particular, a plurality of radio access networks that perform packet data communication using different radio access schemes and other It is suitable for a mobile communication system in which a network is connected via a core network.

It is a figure which shows schematic structure of the mobile communication system between the heterogeneous radio systems concerning Embodiment 1 of this invention. It is a block diagram which shows the internal principal part structure of the edge node concerning Embodiment 1 of this invention. It is a flowchart explaining a process when an edge node receives an IP packet addressed to a mobile node from a correspondent node after a handover. It is a characteristic view which shows the packet discard characteristic of the discard process of the IP packet in a discard process part when the upper layer of the received IP packet is TCP. It is a figure explaining the shaping process in case the upper layer of the received IP packet is RTP. It is a flowchart explaining the shaping process in case the upper layer of the received IP packet is RTP. It is a figure which shows schematic structure of the mobile communication system between the heterogeneous radio systems concerning Embodiment 2 of this invention. 7 is a flowchart showing a part of the operation of the mobile communication system when a mobile node hands over to an access point with a different upstream edge node. 5 is a flowchart showing a part of processing operation of a mobile communication system in which an edge node can predict whether or not a mobile node is handed over and a mobile node handover destination access point. It is a block diagram which shows the internal principal part structure of the edge node concerning Embodiment 1 of this invention. It is a figure which shows schematic structure of the mobile communication system between the heterogeneous radio systems concerning Embodiment 4 of this invention.

Explanation of symbols

2 Mobile node 4 Wireless LAN access point 6 Wireless LAN access point area 8 3G access point 10 3G access point area 12 Access network 14 Edge node 16 Core network 18 Edge node 20 Correspondent node 30 IP packet 40 Access network 42 Access network 44 Edge node 46 Edge node 48 Edge node 101 First communication unit 102 Handover target determination unit 103 Band comparison unit 104 Upper layer analysis unit 105 Network information management unit 106 Discard processing unit 107 Shaping unit 108 Second Communication unit 109 Distribution unit

Claims (20)

An edge node used in a mobile communication system in which a plurality of radio access networks that perform packet data communication using different radio access methods having access points and other networks are connected via a core network,
A communication unit that transmits and receives packets to and from the core network and the access network;
A network information management unit that manages and holds network information about the mobile node and the access point notified from the access network and other edge nodes;
A handover target determination unit that determines whether a destination of a packet received by the communication unit is addressed to a mobile node after handover;
For a packet whose destination is determined to be destined for the mobile node after the handover by the handover target determination unit, the link bandwidth or mobile of the access point before and after handover of the mobile node held by the network information management unit A bandwidth comparator that compares the effective link bandwidth of the node;
In the comparison by the bandwidth comparison unit, the link bandwidth of the access point after the handover or the effective link bandwidth of the mobile node is smaller than the bandwidth of the access point before the handover or the effective link bandwidth of the mobile node An upper layer analysis unit that analyzes an upper layer of a packet received by the communication unit and determines whether the packet is a TCP packet, an RTP packet, or another packet;
When the packet received by the receiving unit is a TCP packet, a discard processing unit that performs discard processing of the packet;
When the packet received by the receiving unit is an RTP packet, a shaping unit that performs a shaping process of sending the packet at a predetermined constant rate;
Equipped with a,
The discard processing unit includes a link bandwidth of an access point accommodating the mobile node before handover or an effective link bandwidth of the mobile node, and a bandwidth of an access point accommodating the mobile node after handover, or Varying the discard rate of the TCP packet according to the link bandwidth ratio with the effective link bandwidth of the mobile node;
An edge node characterized by   2. The edge node according to claim 1, wherein the handover object determination unit transfers the packet determined as not destined for the mobile node after the handover to the access network as it is.   In the comparison by the band comparison unit, when the link bandwidth of the access point after the handover or the effective link bandwidth of the mobile node is larger than the bandwidth of the access point before the handover or the effective link bandwidth of the mobile node The edge node according to claim 1, wherein the packet received by the receiving unit is transferred as it is to the access network.   The packet received by the receiving unit is transferred to the access network as it is when the packet received by the receiving unit is a packet other than a TCP packet / RTP packet. Edge node.   The edge node according to claim 1, wherein the discard processing unit varies the discard rate of the TCP packet according to a residence time of the TCP packet at its own edge node.   The edge according to claim 1, wherein the discard processing unit varies the discard rate of the TCP packet according to a moving speed of the mobile node and a communication area of an access point that accommodates the mobile node. ·node.   2. The discard processing unit varies the discard rate of the TCP packet according to the number of mobile nodes accommodated at an access point downstream of its own edge node and the traffic volume of the mobile node. Edge node as described in 8. The edge node according to claim 7 , wherein the discard rate of the TCP packet is varied so that the traffic volume of each of the accommodated mobile nodes is substantially equal.   2. The edge node according to claim 1, further comprising: a distribution unit that distributes the packet to the shaping unit when the packet received by the reception unit is an RTP packet. The edge node according to claim 9 , wherein the distribution unit distributes packets for each access network whose destination is downstream of the own edge node.   When the mobile node is handed over to its downstream access network, the mobile node and the mobile node are handed over from an upstream edge node of the access network in which the mobile node was accommodated before the handover. The edge node according to claim 1, further comprising the network information collecting unit that collects network information related to an access point of an access network accommodated before.   The edge node according to claim 1, further comprising: a prediction unit that predicts whether or not the mobile node is handed over, an access point of a handover destination access network, and an upstream edge node. 13. The edge node according to claim 12 , wherein network information related to the mobile node and the access point before handover is notified to an upstream edge node of the handover destination access network. The discard processing unit includes the predicted link bandwidth of the access point after the handover of the mobile node or the effective link bandwidth of the mobile node, and the bandwidth of the access point in which the mobile node before the handover is accommodated, or The edge node according to claim 12 , wherein the discard rate of the TCP packet is varied according to a link bandwidth ratio with an effective link bandwidth of the mobile node. The disposal processing section predicts the congestion state in said mobile node that has the predicted from the link bandwidth ratio, to claim 14, wherein varying the loss rate of the TCP packet in accordance with the congestion state The listed edge node. The disposal processing section, the predicted number of accommodating the mobile node in the edge node, and claim 12, wherein varying the loss rate of the TCP packet according to the traffic amount of the mobile node Edge node. The disposal processing section to claim 16, wherein the traffic volume of each of the accommodating mobile node in the mobile node, wherein the predicted post-handover vary the loss rate of the TCP packet so as to be substantially equal The listed edge node.   The edge node according to claim 1, wherein the core network and the access network are connected, and the packet received by the communication unit is a packet received from the core network.   The edge node according to claim 1, wherein the other network and the core network are connected, and the packet received by the communication unit is a packet received from another network. A plurality of radio access networks performing packet data communication by different radio access methods having an access point;
Another network different from the radio access network;
A core network connecting the plurality of radio access networks and the other network;
An edge node connecting the core network and the plurality of radio access networks or the other networks;
A mobile communication system constructed with
The edge node is
A communication unit that transmits and receives packets to and from the core network and the access network;
A network information management unit that manages and holds network information about the mobile node and the access point notified from the access network and other edge nodes;
A handover target determination unit that determines whether a destination of a packet received by the communication unit is addressed to a mobile node after handover;
For the packet whose destination is determined by the handover target determining unit to be addressed to the mobile node after the handover, the link bandwidth or mobile of the access point before and after handover of the mobile node held by the network information management unit A bandwidth comparator that compares the effective link bandwidth of the node;
In the comparison by the bandwidth comparison unit, the link bandwidth of the access point after the handover or the effective link bandwidth of the mobile node is smaller than the bandwidth of the access point before the handover or the effective link bandwidth of the mobile node An upper layer analysis unit that analyzes an upper layer of a packet received by the communication unit and determines whether the packet is a TCP packet, an RTP packet, or another packet;
When the packet received by the receiving unit is a TCP packet, a discard processing unit that performs discard processing of the packet;
When the packet received by the receiving unit is an RTP packet, a shaping unit that performs a shaping process of sending the packet at a predetermined constant rate;
Equipped with a,
The discard processing unit includes a link bandwidth of an access point accommodating the mobile node before handover or an effective link bandwidth of the mobile node, and a bandwidth of an access point accommodating the mobile node after handover, or Varying the discard rate of the TCP packet according to the link bandwidth ratio with the effective link bandwidth of the mobile node;
A mobile communication system.

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