Handover of a mobile node between networks of different technologies in a mobile ip telecommunications system

The present invention relates to a communication system and a communication method, and also relates to a mobility manager capable of operating in a communication system that provides mobile Internet protocol related services to mobile nodes via a plurality of access networks.

There are various types of mobile wireless networks that can provide mobile-related services to mobile user devices. For example, the GSM (Global System for Mobiles) network provides functions for data and voice communication via fixed capacity wireless communication channels. UMTS (Universal Mobile Telecommunications System), on the other hand, offers increased flexibility when delivering higher data rates to mobile user devices, as well as roaming capabilities enabled by the cellular architecture. On the other hand, wireless LAN (Wireless Local Area Networks; WLAN) standard, for example, IEEE called WIFI 802.11B provides features for high data rate communication within so-called WLAN hotspots. Such WLANs can provide substantially higher data rates than those provided by cellular mobile wireless architectures such as GSM and UMTS. In addition, WLANs are often chaotic in that a single mobile user can occupy more of the available data bandwidth than other mobile users.

Many applications utilize the Internet Protocol to support data communications, such as multimedia services. Therefore, communication services can be provided by propagating Internet Protocol packets over a variety of different networks. The application need not be aware of the type of network through which the Internet Protocol packet is transmitted. Thus, in the case of wireless communication, the application can propagate internet packets over either the GSM network or the WLAN. However, those different types of mobile wireless networks can provide significantly different communication bandwidths and the quality of service they can support may vary depending on the communication bandwidth provided by the mobile access network. Thus, communication services can be provided using different communication session levels, each level providing different quality of service as determined by the access network with which the mobile node is currently communicating. Different types of media can be transmitted for each communication session level. Thus, for example, one communication session level can support video, while the other levels can only support audio.

European Patent No. 1435748 allows the Mobility Manager to notify application servers that provide communication services to mobile nodes that a change in subscription from one access network to another on a mobile node has been suspended or completed. The configured communication system is disclosed. Therefore, the application server can change the communication session level before or after the change of subscription depending on whether there is an increase or decrease in the communication session level. The communication session level provides different quality of service capable of supporting different types of media. Thus, the application server can adapt the communication session level to the intent of maintaining at least one service subscribed to by the user. To determine when a subscription change has occurred, the mobility manager receives an access network evaluation message from the access gateway of the associated mobile access network to identify when a handover occurs.<patcit num="1"><text>European Patent No. 1435748</text></patcit>

<p> According to one aspect of the invention, the communication system provides mobile internet protocol related communication services to mobile nodes via a plurality of access networks. Each of those access networks includes an access gateway that controls access to the access network by the mobile node, and the communication service is provided within an Internet Protocol communication session with different levels. The system includes a mobility manager server that includes an application layer mobility manager that functions to receive link quality assessment messages (MNEs) from the mobile node, each of which has a message (MNE) from the mobile node on the access network. Includes one or more measurements with link quality indications available for the mobile node. In addition, the mobility manager functions to receive an application server message from an application server that provides the communication service to the mobile node, and the application server message is currently available for the mobile node in the access network. Change the communication session level depending on the link quality available. The mobility manager also functions to receive access network evaluation messages from each of the access gateways of the access network with which the mobile node is communicating through it. The access network evaluation message is the total communication bandwidth currently used by the mobile node communicating over the access network according to the radio communication resources of the wireless access interface provided by the access network currently in use. The indication of the congestion state of the access network to the above is shown. The mobility manager may change the subscription of the first mobile node from one of the first and second access networks to the other of the first and second access networks. Or, it functions to direct at least one of the communication session level changes of the first mobile node. The subscription change, or communication session level change, is the congestion condition of the first or second access network, the link quality currently experienced by the first mobile node, the application server message, and the said. It is performed according to the level of service quality subscribed to by the first mobile node with respect to the level of service quality subscribed to by the second mobile node subscribed to the first or second access network.</p><p> An embodiment of the present invention is a WLAN (Wireless Local Area) independent of the mobile internet protocol v4 / v6 stack. Provides a communication system that seeks to maintain continuity and quality of service for communication sessions to mobile nodes, even on chaotic access networks such as Networks). In addition, the congested access network can alleviate the congestion by controlling the bandwidth of the user. Subscription changes between mobile networks (mobile node handover) are the link quality currently experienced through the access network to which the mobile node currently belongs, the amount of congestion present on the mobile network, and. It is controlled according to the level of service quality to which the mobile node subscribes. To this end, mobile nodes subscribed to higher quality services are given priority over mobile networks that offer higher communication bandwidth than mobile nodes subscribed to lower quality services. A network and quality of service reselection algorithm is performed by the mobility manager to control access to the mobile network. In addition, the mobility manager according to some embodiments of the present invention has the effect that congestion on the first network reduces the quality of service for mobile nodes that have subscribed to higher quality of service. Arranged to force a node to hand over to a different mobile network.</p><p> International Publication No. 03/047296 discloses a configuration in which the messages that form part of the Mobile IPV6 Internet Protocol are extended to provide functionality for mobile nodes and mobility managers that convey link quality related messages. doing. Specifically, the mobile node is disclosed as transmitting a handover request only if the link quality on its current communication mobile access network is degraded. Therefore, if the mobile node is in coverage of a higher capacity access network than its current access network, the mobile node will remain on its current access network. Moreover, when using only the mobility manager, seamless mobility is achieved, but quality of service is not possible.</p><p> In the case of IEEE 802.11 WLAN examples, the spectrum is untuned and free competition, as opposed to cellular schemes, such as GSM, GPRS or UMTS, where mobile nodes are a resource provided by the network. .. The unfavorable result is that traffic on only one mobile node can affect the performance of all other mobile nodes. For example, one of the mobile nodes receiving UDP video streaming and at the hotspot coverage boundary of a WLAN can consume a significant amount of the available communication bandwidth. As a result of link quality degradation, the hotspot throughput can drop to zero.</p><p> An embodiment of the present invention can provide a mobility manager having the following features. -Control of the access network of mobile nodes is performed independently of the MIPv4 / v6 stack when messages defined between different entities are written in the application layer. Dynamically determine and select the appropriate access networks available for mobile node communication sessions using the Network and Quality of Service Reselection Algorithms (NQRA). The possibility of providing minimum quality of service for communication sessions is guaranteed, or at least increased, even on chaotic access networks such as IEEE 802.11 WLANs. -A congested access network such as an IEEE 802.11 WLAN access point can mitigate the congestion. -Assign mobile nodes to different access networks according to the operator's policy.</p><p> An embodiment of the present invention is defined to process a message defined between a mobility manager and a mobile node, a message defined between a mobility manager and an access gateway, and a decision regarding a mobile node and an access point. It uses a network and quality of service reselection algorithm that is and is performed by the mobility manager.</p><p> In some embodiments, the mobility manager provides the first mobile node with an access network that gives the first mobile node an increase in the available communication bandwidth for the first mobile node in preference to the second mobile node. The allocation of communication bandwidth to the second mobile node can be reduced in order to instruct to change the subscription to or to maintain the communication bandwidth for the first mobile node. This preference can be made based on the fact that the first mobile node has subscribed to a higher quality of service level. Alternatively, the mobility manager may say that if the first and second mobile nodes subscribe to the same quality of service level, the communication bandwidth used by the second mobile node will be the second. It can be determined that it is used more inefficiently than the communication bandwidth used by the mobile node. Alternatively, the first mobile node is preferred because the communication protocol used by the second mobile node can better cope with the loss of Internet Protocol packets.</p><p> According to the description below, the term communication session level means identifying communication quality of service, which allows the use of different media types. Typically, the higher the session level, the higher the link communication bandwidth, which can be used to support media types that require higher communication bandwidth.</p><p> Various other aspects and features of the present invention are defined in the appended claims and include a mobility manager and a method of providing mobile internet protocol related services to mobile nodes via multiple access networks.</p>

Embodiments of the present invention will then be described as just one example with reference to the accompanying drawings, and similar components are described with similar reference numerals. -Fig. 1 is a schematic block diagram of a functional Internet Protocol multimedia architecture according to an embodiment of the present invention. -Fig. 2 is a schematic block diagram of the communication system used by the Internet Protocol multimedia system of Fig. 1 to provide communication services to mobile nodes using multiple access networks. -Figure 3 is a schematic diagram of the message flow and the process steps performed by the mobility manager shown in Figure 2 to control access to the access network by mobile nodes. -Figure 4 is a flow diagram illustrating the process of controlling mobile node subscription changes and / or communication session level changes between mobile access networks performed by the Mobility Manager. -FIGS. 5A and 5B are flow diagrams illustrating examples of network and quality of service reselection algorithms performed in the process shown in FIG. -FIG. 6 is a flow diagram illustrating a second embodiment of a network and quality of service reselection algorithm capable of performing congestion control performed in the processes shown in FIGS. 4 and 5A.

(Explanation of an exemplary embodiment) (Abbreviation) AG access gateway ANE Access Network Evaluation ANI Access Network Identifier AP access point API access point identifier BA binding acknowledgment BU join update GPRS general-purpose packet radio service Global system for GSM mobile communication HA Home Agent HI handover order IPMM IP Mobility Management LAC location area code MAC medium access control MM Mobility Manager MN mobile node NQRA Network and Quality of Service Reselection Algorithm PLMN Public Land Mobile Network QoS service quality SSID service setting identifier UMTS Universal Mobile Communication Service WLAN wifi

In the embodiment of the present invention, the application layer mobility manager is provided in the mobility manager server that executes mobility management independently of the version of a specific Internet protocol. Mobility manager messages are written within the application layer instead of associating the message with a mobile internet protocol standard. As a result, in practice, those messages can be markup language-based messages such as XML on TCP / IP or UDP / IP.

Figure 1 shows a comprehensive system architecture for the elements that make up the embodiments of the present invention. In FIG. 1, the application server AS is arranged to execute, for example, an application layer program that provides a multimedia communication service to the mobile node MN. The application server AS is running a multimedia communication session, but the communication links through which the service is provided are through communication channels that can be affected over a number of mobile communication access networks. Use a supported internet protocol. Briefly, the communication bandwidth can vary depending on the type of access network with which the mobile node communicates. This is because the communication bandwidth that can be provided by the access network differs between different access networks due to the wireless communication interface provided by the access network. The mobility manager MM is provided to control a communication session, more specifically, a handover of the mobile node from one access network to another. This is done by running a network and quality of service reselection algorithm based on the user profile information. The user profile information is provided by the mobility manager register 2 and can include indications of the quality of service level subscribed to by the user of the mobile node. In order to control the subscription of mobile nodes among a large number of access networks, based on the current load on the access network, the mobility manager may access network evaluation message from the access gateway 4 of the access network. ANEag) is received. The access gateway 4 is an embodiment of a point in the access network through which all incoming and outgoing Internet Protocol packets are transmitted.

In FIG. 1, the mobility manager server 6 efficiently configures a home agent for Internet Protocol communication with mobility manager-specific messages. The mobility manager also includes a hand over policy server (HPS) that manages IPMM-specific messages and determines whether to perform handover and / or communication service level changes. As mentioned above, the IPMM register 2 forms a database that stores user context information (user profile, wireless environment, session parameters) along with information about different access network states. The access gateway AG4 activates resources for a given access network and supports access resource monitoring. For example, in the case of a WLAN, an access gateway is provided to monitor resources, fetch information from all access points in the WLAN, and evaluate the load on available communication resources in the network.

As described above, the application server (AS) manages one or more applications that provide communication services to one or more parties by utilizing the Internet Protocol communication with the mobile node.

A good perception of the operation of the system shown in FIG. 1 can be understood by FIG. 2 showing an exemplary embodiment of the present invention. In FIG. 2, three access networks 20, 22, and 24 that provide mobile communication to mobile nodes 26 and 28 are shown. From the embodiment shown in FIG. 2, the first access network 20 operates according to the UMTS standard, the second access network 22 operates according to the GSM standard, and the third access network 24 operates according to the WLAN standard. The third access network 24 is the IEEE, commonly referred to as WIFI. It may operate according to the 802.11B standard. In FIG. 2, the third access network 24 is composed of two subnetworks that form a localized centralized area or hotspot in which mobile communication via the WLAN standard is possible. Subnetworks 24.1 and 24.2 each include access points 30 and 32, through which Internet Protocol packets are transmitted and received by mobile nodes operating within the coverage area formed by subnetworks 24.1, 24.2. Ru. Therefore, in the case of the third access network, the access gateway 34 is provided to receive the Internet Protocol message from the access points 30 and 32. The first and second access networks also include access gateways 36, 38 that function to propagate the access network evaluation message (ANEag) to the mobility manager server 40, in which case the message is the application layer mobility manager. Received by. According to the elements shown in FIG. 1, the mobility manager server is an application server that executes a mobility manager register 42 in which user context information is stored and an application layer program for providing communication services to mobile nodes 26 and 28. Also includes 44.

As described above, an embodiment of the present invention realizes a function of controlling access to various access networks of a mobile node according to a subscribed quality of service level. For example, a user of the mobile node may subscribe to one of three quality of service levels, which in the following description will be referred to as bronze, silver and gold. The mobility manager in the server 40 determines access to the access network by the mobile node with the quality of service subscribed to, the quality of links available from the mobile node via the access network, and the congestion of the access network. Control based on the combination of.

In the case of the WLAN access network embodiment, unlike cellular mobile communication networks such as GSM and UMTS, communication is chaotic and free competition. As a result, any mobile node can secure a larger percentage of available communication bandwidth than other mobile nodes. For example, one of the mobile nodes can receive a UDP video stream and, as a result, can consume a significant percentage of the bandwidth available on the WLAN. As a result, the quality of communication links to other mobile nodes in the WLAN can be reduced to zero. Briefly, embodiments of the present invention implement a mobility manager capable of managing access to the access network of the mobile node using network and quality of service reselection algorithms. As a result, the first mobile node 26 can be instructed to hand over to the third access network 24 in preference to the second mobile node, and the second mobile node can be instructed to hand over to the third access network 24. It can be instructed to hand over from the third access network to the first access network 20. This preference is the result of higher priority, for example, because the first mobile node subscribes to a higher quality of service level.

The operation of the embodiment of one embodiment will be described with reference to the flow chart shown in FIG.

In FIG. 3, in the first step S2, the mobile node can transmit the link quality evaluation message MNE to the mobility manager 40. The access gateway can also propagate the access network evaluation message ANEag to the mobility manager to report on the state of communication bandwidth consumed.

The application server executes an application layer program that provides a communication service to a mobile node. The application server requests that the application server message be sent to the mobility manager to increase the bandwidth currently experienced by the mobile node so that it can deliver, for example, a video message.

In message exchange S6, the mobility manager updates the user context associated with the mobile node associated with the currently received access network evaluation message, link quality evaluation message, or application server message received in steps S2 and S4. ..

Step S8: The mobility manager then queries the mobility manager register 42 for user context information for use in network and quality of service reselection algorithms. The user context information includes a service quality level and the like subscribed by the user of the mobile node.

Step S10: Briefly, then to determine if a mobile node should be handed over to another mobile access network with lower relative communication resources, eg, from a WLAN network to a cellular mobile network, and / Or the network and quality of service reselection algorithm described above is executed to determine if adaptation to the current communication session level is necessary. Accordingly, this requires session notification and application adaptation features. In contrast, the process steps performed by a mobile node to hand over to an access network with higher relative communication parameters are shown in the lower half of Figure 3. These steps can be summarized as follows.

Step S12: The mobility manager determines that the mobile node can access an access network that provides higher communication bandwidth, for example, a handover to a wireless LAN. Accordingly, the mobility manager issues a handover command HI.

Step S14: If this handover is successful, the mobile node informs the mobility manager of the new location by sending a location update message (Mobile IP Binding Update message).

Step S16: The mobile node then sends a handover instruction acknowledgment and includes an access network evaluation message with a context option set to high (HI ACK MNE).

Step S18: The mobility manager then acknowledges the location update message.

Step S20: The mobility manager then updates the context for the user by transmitting information to the IPMM register 42, which is later acknowledged. Here, two examples of the network and quality of service reselection algorithm will be described. However, whether or not the mobile node should be instructed to hand over from the second mobile access network to the first mobile access network and vice versa, and / or adapt to its current session level. The general process of making a decision is described here. In one embodiment, the first mobile access network with a relatively high communication bandwidth can be a WLAN and the second mobile access network with a relatively low communication bandwidth is cellular. It can be a mobile wireless network. The general operation of the mobility manager is represented by the flow diagram shown in FIG. 4, summarized as follows.

Step S30: The mobility manager receives a link quality evaluation message (MNE) from the mobile node that evaluates the current communication quality that the mobile node is currently experiencing through the access network to which it belongs. The mobility manager also receives an application server message from the application server requesting an increase or decrease in the communication bandwidth provided via the access network to which the mobile node is currently subscribed.

Step S32: The mobility manager also receives an access network evaluation message (ANEag) from each access gateway of the access network that reports on the current congestion status for the communication resource in use.

Step S34: The mobility manager obtains contextual information from the mobility manager register. The user context information includes a user profile, quality of service indications (bronze, silver, gold) subscribed to by the user, and previous evaluation messages and communications of the current access network subscribed to by the mobile node, etc. Includes any other information related to the management of the mobile node.

Step S36: One mobile access network for each mobile node based on the current congestion status of the mobile access network to which the mobile node is subscribed, the conditions of the subscribed communication session service level and the current available link quality. At least one network and service for link quality assessment messages (MNEs), application server messages and access network assessment messages (ANEag) to determine if to instruct another mobile access network to handover from The quality reselection algorithm is executed.

Step S38: From the results of the network and quality of service reselection algorithm, the mobility manager determines whether the mobile node should hand over to another mobile access network. If a handover is required, the process proceeds to step S44, otherwise it proceeds to step S40.

Step S40: If a handover is not required, the mobility manager should adapt the mobile node to its current communication session level, for example, according to the requirements to ease the congestion of the mobile access network to which the mobile node is currently subscribed. Judge whether or not it is possible. If no adaptation to the communication session level is required, the process proceeds to step S49. If adaptation to the communication session level is required, the process proceeds to step S42.

Step S42: The mobility manager adapts its communication session level to the mobile node in order to adapt to the decrease or increase in the communication bandwidth allocated from the mobile access network to which the mobile node is currently subscribed. To work with the application server to instruct. As shown in FIG. 4, this is done by the mobility manager and reports to the application server that the mobile node should reduce its communication bandwidth consumption. As a result, the application server can instruct the mobile node to reduce its communication session level and reduce the communication bandwidth it consumes.

Step S44: If the mobile node should be handed over to a different mobile access network, the mobility manager determines whether the link communication bandwidth available to the mobile node should be increased or decreased. .. If the link communication bandwidth should be increased, the process proceeds to step S46, otherwise the process proceeds to step S47.

Step S46: If the mobile node should hand over to a different network, the mobility manager transmits a Hand Over Instruction (HI) to instruct the mobile node to hand over to a different access network. In step S48, report to the application server.

Step S47: If the link communication bandwidth should be reduced or kept the same, the mobility manager reports the subscription change to the application server before the subscription change is made. Therefore, according to the technology disclosed in EPO 1435748, the application server can adapt to the communication session level before the handover is performed. Alternatively, if the link communication bandwidth remains the same, the handover may be performed and then notified to the application server.

Step S48: The application server receives a report from the mobility manager of a decision regarding a change in subscription from one mobile access network to another.

Step S49: If a handover or communication session level adaptation is not required, the next mobile node is revisited as to whether a handover is required.

The flow diagram shown in FIG. 4 shows that in step S36, the mobility manager executes at least one algorithm to determine whether to instruct the mobile node to perform a handover or session adaptation. These network and quality of service reselection algorithms can, of course, be part of the same algorithm. However, it is useful to separate the algorithms to illustrate exemplary embodiments of the invention. Next, examples of these algorithms will be described.

(Network and quality of service reselection algorithm 1)

5A and 5B show, for example, a flow diagram illustrating the operation of the mobility manager in step S36 of the flow diagram of FIG. These steps by the first network and quality of service reselection algorithm shown in FIGS. 5A and 5B can be summarized as follows.

Step S50: For each mobile node, it is determined which access network can support the guaranteed minimum link communication bandwidth required to support the lowest communication session level. Each mobile access network is then added to the list of possible access networks for that mobile node.

Step S52: For each mobile access network on the list of mobile access networks that can support the minimum communication bandwidth of the lowest communication session, the mobility manager evaluates the link quality currently available. To this end, the Mobility Manager is a real or possible link that each mobile node may have from the access network it is currently subscribed to, or from one or more other access networks. Match the information provided by the Link Quality Assessment Report on communication bandwidth. The mobility manager determines whether the currently available communication bandwidth is sufficient to support the lowest level of communication session or can support a higher level of communication session.

Step S54: The mobility manager prefers each mobile node because the mobile node provides higher link communication bandwidth on the current access network or because the target access network provides higher link communication bandwidth. Determine if it has a higher priority than other mobile nodes on the target's access network. The higher bandwidth allows the mobile node to experience improved quality communication session levels such as video instead of voice, eg, over the access network.

Step S56: Does the currently evaluated mobile node have a higher priority than at least one other mobile node on the current access network or on the target access network?

Step S58: Step S58.1 If the mobile node has a high priority, the mobility manager will hand over to the mobile node to the target access network and / or of the communication link bandwidth. Instruct to change the communication session level as it increases. However, in order to determine if the mobility manager can allow the mobile node to hand over to the target network, the mobility manager follows the behavior represented by the flow diagram of FIG. 6 described below. In step S58.2, the congestion management operation can be performed.

Step S60: If the mobile node does not have a higher priority than the other mobile nodes, the mobility manager will send another mobile node to the current mobile access network to which the mobile node is currently subscribed. Another mobile node that has a higher priority or subscribes to another mobile network that wants to hand over to the current mobile access network has a higher priority than that mobile node. Determine if you have it.

Step S62: Is there a higher priority mobile node? If so, the process proceeds to step S64, otherwise the process proceeds to step S78.

Step S64: If there is a higher priority mobile node, the mobility manager determines if the current mobile access network is congested. Is the current mobile access network congested? If the access network is congested, the process proceeds to step S66, otherwise the process proceeds to step S80.

Step S66: If the current mobile access network is currently congested, the mobility manager will determine if there is a current communication session level or another mobile access network that can support a lower communication session level. to decide.

Step S68: Can another access network provide a communication link bandwidth that supports the current communication session level, or a lower communication session level? If there is another mobile access network that can support the current communication link bandwidth, the process proceeds to step S70, otherwise the process proceeds to step S72.

Step S70: The mobility manager determines that the mobile node should hand over to another mobile access network that can provide communication link bandwidth that supports the current communication session level, and the process is shown in Figure 4. Proceed to step S38 of.

Step S72: The mobility manager determines if the current mobile access network can support acceptable link communication bandwidth for lower communication session levels.

Step S74: Can the current mobile access network support lower communication session levels? If the current mobile access network can support a lower communication session level, the process proceeds to step S76, otherwise the process proceeds to step S77.

Step S76: The mobility manager determines that the communication session level should be adapted to a lower level that can be supported by the current mobile access network, and the process proceeds to step S40 of FIG.

Step S77: If the current access network is unable to support a lower communication session level, the mobility manager will say that the other network will support a lower communication session level with respect to what was determined in step S66. If possible, the handover to the other network is instructed, and the process proceeds to step S78. If the other network is unable to support the lower communication session level, the process proceeds to step S82.

Step S78: This step is the same as in Step S70, where the mobility manager should hand over to another mobile access network where the mobile node can provide communication link bandwidth to support the current communication session level. The process proceeds to step S38 in FIG.

Step S80: The mobility manager determines that the handover is not necessary and that the communication session level adaptation is not necessary, and the process proceeds to step S38 or step S40.

Step S82: The mobile node remains on the current access network, but the communication session for the mobile node is closed.

There are various parameters that can be used to prioritize one mobile node over another. For example, the mobility manager may not only subscribe to quality of service, such as bronze, silver and gold, but also The load on which the mobile node is located on the access network, Is the mobile node exceeding expectations regarding agreed consumption of communication bandwidth? Does the mobile node indicate that a particular access network is prioritized? For the purpose of guaranteeing the stability of the access network, Can be identified based on.

(Network and quality of service reselection algorithm 2)

As described above, according to step S38 of FIG. 4, the second algorithm for determining whether the mobile node should hand over to the other access network due to the congestion of the other access network is the handover to the mobile node and /. Or determine access network congestion to determine if session adaptation is required. FIG. 6 shows an exemplary embodiment in which the mobile node is instructed to hand over based on the current congestion of the access network. FIG. 6 shows a flow chart illustrating the operation of the mobility manager. Figure 6 can be summarized as follows.

Step S90: The mobility manager receives an access network evaluation message from each access gateway of the access network.

Step S92: From the access network evaluation message, the mobility manager determines if a particular access network is congested. If there is no congestion, the process proceeds to step S90 to receive and evaluate the next access network evaluation message. If the mobile access network is congested, the process proceeds to step S94.

Step S94: If the mobile access network indicates that it is congested, the mobility manager will tell each mobile node currently subscribed to the access network that one of those mobile nodes will Determine if it has a lower priority than other mobile nodes and if the communication session can continue over a different access network. As a result, the mobility manager identifies whether the lower priority mobile belongs to the currently congested access network. The priority of one mobile node over other mobile nodes can be determined from any of the following factors. -Can the mobile node operate via another access network, for example, is the mobile node capable of GPRS? -Subscription levels to which the mobile node subscribes, such as bronze, silver and gold. The current bandwidth that a mobile node consumes over other mobile nodes so as to give the high-consumed mobile node a lower priority than the mobile node that consumes less communication bandwidth. -The length of the medium access control frame generated by the mobile node. A forwarding protocol used, for example, when UDP is preferred as a forwarding protocol over TCP, which can adapt to packet loss.

Step S96: Is a lower priority mobile node subscribed to a congested access network? If there is a lower priority mobile node, the mobility manager proceeds to step S98, otherwise processing continues from step S100.

Step S98: The mobility manager performs steps S66 through S80 to hand over to another mobile access network and proceed to step S38, or stay in the current network and proceed to step S40 in FIG. to decide.

Step S100: The mobility manager tells the mobile node that the handover is unacceptable to the congested mobile access network and that the increase in communication link bandwidth is subscribed to the congested access network. It is decided that it will not be realized, and as a result, it is not possible to allow an increase in the communication session level.

Next, in order to implement the mobility manager described above, the format and grammar of the message to and from the mobility manager will be described. To implement a mobility manager that is independent of the IP version, the mobility manager message presented below will have to consider at least two internet protocol standards, mobile IPv4 and mobile IPv6. Instead of associating with, it is written in the application layer. In practice, these messages can be XML messages over TCP / IP or UDP / IP.

There are three main messages. That is, MNE: The mobile node is a component that allows users to access their applications wherever they are. The mobile node composes a message (MNE) containing information about its available access network quality and sends it to the mobility manager. -ANEag: The access point is the node to which the mobile node belongs. The access gateway collects information about its current load from the access point, i.e. the percentage of radio resources used, variation and number of connected MNs. An access gateway is a node that collects information on several access points, composes a message (ANEag), and sends it to the mobility manager. -HI: Handover instruction message transmitted from the mobility manager to the mobile node.

(A.1-MNE) First, the format of the message MNE is shown. The message is divided into two parts, a common part and a measured part containing one or more measurements.

The intersection contains the following information: message type (1 byte): 02 identifies the evaluation message. sequence number (1 byte): This value is updated each time the MNE is sent by a device (mobile node or access gateway). lifetime (1 byte): This value gives the lifetime of the message. sender message type (1 byte): Identifies the type of device (01 = access gateway, 02 = mobile node) that sends the message. sender identifier (6 bytes): This value uniquely identifies the device sending the message. The identifier can be a MAC address. context_option (1 byte): This value indicates whether the message is a user context enabled MNE, HI ACK MNE, immediate HO MNE, or regular MNE. number of measurements (1 byte): This value gives the number of measurements reported in the message.

The grammar of the measured value part is as follows. access network type (1 byte): Identifies the type of access network (01 = cellular, 02 = 802.11 .. ..). ani_length (1 byte): This value gives the length of the ANI in bytes. access Network Identifier (1-32 bytes): This value uniquely identifies the access network. The identifier is PLMN for GPRS and SSID for WLAN. access Point Identifier (0-6 bytes): This value uniquely identifies an access point in the access network and is its MAC address. quality (1 byte): This value gives the current quality of the link. current (1 byte): This value indicates whether the access network is the current access network. gprs_slot_up (4 bits): This value exists only for cellular networks and gives the power of mobile nodes in the uplink. gprs_slot_down (4 bits): This value exists only for cellular networks and gives the power of mobile nodes in the downlink.

(A.2-AN Eag) Next, the format of the ANEag message is presented. This message is divided into two parts, a common part with an MNE message and an individual measurement part containing one measurement for one access point.

The intersection contains the following information: message type (1 byte): 02 identifies the evaluation message. sequence number (1 byte): This value is updated each time the ANEag is sent by the access gateway, allowing the MM to ignore ANEag messages that are no longer in use. lifetime (1 byte): This value gives the lifetime of the message. sender message type (1 byte): Identifies the type of device (01 = access gateway, 02 = mobile node) that sends the message. sender identifier (6 bytes): This value uniquely identifies the access gateway sending the message, which is a MAC address or other identifier.

The measurement part contains the following information. access network type (1 byte): Identifies the type of access network (01 = cellular, 02 = 802.11 .. ..). Access Point Identifier (0-6 bytes): This value uniquely identifies an access point in the access network, the identifier being MAC @. connected_MN (2 bytes): This value gives the number of mobile nodes associated with the access point. load: This field is divided into several subfields. That is, -Value: The load value processed by the AG for this AP. -Variation: Expansion of this value. If desired, the ANEag message may also include the following fields: Packet lost: The number of packets lost by the access point (including received and transmitted packets) per second. · The mobile node: Contains information about all mobile nodes connected to the AP. MAC address of the MN: Identifies the mobile node connected to the access point (WLAN MAC @). -Statistics: Give MM more information. That is, -Average received packet length for this MN. -Average transmission packet length for this MN. -The number of bytes sent by this MN per second. -The number of bytes received by this MN per second.

<tables num="1"><img file="JP4989484B2_D0001.tif" /></tables>

Note: More fields can be added to the MNE or ANEag if desired. Those fields -Modulation used by the mobile node to communicate with the AP. Packet loss, delay and jitter uplink / downlink for mobile nodes.

(1.3-HI) The following is the format of the HI message. message type (1 byte): 01 identifies the handover instruction message. sequence number (1 byte): This value is updated each time a handover instruction is sent to the same mobile node. access network type (1 byte): Identifies the type of access network (01 = cellular, 02 = 802.11 .. ..). ani_length (1 byte): This value gives the length of the access network identifier in bytes. access Network Identifier (1-32 bytes): This value uniquely identifies the access network. access Point Identifier (0-6 bytes): This value uniquely identifies the access point in the access network.

Various modifications can be made to the above-described embodiments without departing from the scope of the present invention. For example, although the embodiment is described for WLANs that comply with the IEEE 802.11 standard, it can be correctly understood that other WLAN standards as well as cellular mobile wireless networks other than GSM and UMTS are also suitable.

Various other aspects and features of the present invention can be understood in the following specific embodiments. -The access network evaluation message is such that the congestion condition does not have enough communication bandwidth available from the first access network to support the quality of service subscribed for the communication session. At least one communication bandwidth used by the first mobile node is used less efficiently than the communication bandwidth used by other mobile nodes subscribed to the same level of service quality. If the communication protocol used by the first mobile node is able to cope with the loss of network protocol packets, then the mobility manager will call the first mobile node the first. A communication system that functions to determine that a subscription should be changed from an access network to the second access network, or to reduce the communication bandwidth consumed on the first access network. .. -The access network evaluation message received from the access gateway of the first network indicates that there are sufficient communication resources available from the first access network due to the congestion condition, and the first mobile The node includes a communication interface that communicates over the first access network, and the application server message indicates that the mobile node will benefit from higher relative communication link bandwidth. If, the mobility manager is lower relative communications link bandwidth with a more relative to said first access network said first to change a subscription from Ru said second access network to said first access network A communication system that functions to direct the mobile node of. The mobility manager responds to the link quality evaluation message (MNE) from the first mobile node and, in collaboration with the access network evaluation message, sets the current communication session level from the second mobile node. A communication system that determines that it can only be supported by a priority change of subscription to the first access network. The communication session level given to the first mobile node is not the bandwidth required to adapt to the communication session level given to the second mobile node, but is available from the first access network. The mobility manager may change subscriptions to the first mobile network in preference to the second mobile node that subscribes to the same quality of service level if it can be adapted within the same communication bandwidth. A communication system that functions to determine that the first mobile node should be instructed. -The first mobile node and the second mobile node are currently subscribed to the second access network, and the first mobile node is instructed to change the subscription to the first access network. And the second mobile node is not directed, the communication system. The first mobile node is subscribed to the second access network, the second mobile node is currently subscribed to the first access network, and the mobility manager is the second mobile. A communication system that functions to instruct a node to change subscription to the second access network and to instruct the first mobile node to change subscription to the first access network. The first mobile node is subscribed to the second access network, the second mobile node is currently subscribed to the first access network, and the mobility manager is the first. It functions to instruct the second mobile node to change the communication service level in order to adapt to the communication bandwidth required for mobile, and the first mobile node is assigned to the first access network. A communication system that is instructed to change subscriptions. A communication system in which the first access network is a WLAN and the second access network is a cellular mobile wireless network. The access network evaluation message (ANEag) indicates that the communication bandwidth is available from the first access network to support the communication session level for the first mobile node. When a mobile node includes a communication interface that communicates over the first access network, and the first mobile node subscribes to a higher level of service quality than the second mobile node. The first to change subscriptions from the second access network, which has a lower relative communication bandwidth to the first access network, to the first access network in preference to the second mobile node. A mobility manager that acts to determine that one mobile node should be instructed. The second mobile node subscribes to a higher quality of service level than the first mobile node, and the communication bandwidth from the first access network used by the first mobile node is increased. The first mobile node moves from the first access network to the second access network when it has the effect of inadequate available communication bandwidth on the second mobile node. By deciding that the subscription should be changed, or by changing the communication session to a different level with a lower communication bandwidth, the communication bandwidth consumed on the first access network A mobility manager that works to reduce. -In response to the link quality evaluation message (MNE) from the first mobile node, in collaboration with the access network evaluation message, the current communication session level is changed by changing the subscription to the first access network. A mobility manager that determines that only can be supported and that the subscription change is implemented in preference to the second mobile node. Available from the first access network rather than the bandwidth required to adapt the communication session level given to the first mobile node to the communication session level given to the second mobile node. The first to change subscription to the first mobile network in preference to the second mobile node subscribed to the same quality of service level if it can be adapted within the same communication bandwidth. A mobility manager that acts to determine that a mobile node should be instructed. -The first mobile node and the second mobile node are currently subscribed to the second access network, and the first mobile node may change the subscription to the first access network. A mobility manager that is instructed and the second mobile node is not instructed. -The first mobile node is subscribed to the second access network, the second mobile node is currently subscribed to the first access network, and the second mobile node is joined to the second. A mobility manager that functions to instruct the second access network to change subscriptions and to instruct the first mobile node to change subscriptions to the first access network. -The first mobile node is subscribed to the second access network, the second mobile node is currently subscribed to the first access network, and the mobility manager is the second. It functions to instruct the mobile node to change the communication service level to adapt to the communication bandwidth required by the first mobile node, and the first mobile node is the first access network. A mobility manager who is instructed to change subscriptions to.

<figref num="1">FIG. 6 is a schematic block diagram of a functional Internet Protocol multimedia architecture according to an embodiment of the present invention.</figref><figref num="2">FIG. 1 is a schematic block diagram of a communication system used by the Internet Protocol multimedia system of FIG. 1 to provide communication services to mobile nodes using a plurality of access networks.</figref><figref num="3">It is a schematic diagram of the process steps performed by the mobility manager shown in FIG. 2 to control the flow of messages and access to the access network by mobile nodes.</figref><figref num="4">FIG. 5 is a flow diagram illustrating the process of controlling mobile node subscription changes and / or communication session level changes between mobile access networks performed by the Mobility Manager.</figref><figref num="5A">It is a flow diagram explaining the example of the network and service quality reselection algorithm executed by the process shown in FIG.</figref><figref num="5B">It is a flow diagram explaining the example of the network and service quality reselection algorithm executed by the process shown in FIG.</figref><figref num="6">FIG. 5 is a flow diagram illustrating a second embodiment of a network and quality of service reselection algorithm capable of performing congestion control executed in the processes shown in FIGS. 4 and 5A.</figref>

Code description

2 Mobility manager register 4 Access gateway 6 Mobility Manager Server 20 Access network 22 Access network 24 Access network 26 mobile node 28 mobile node 30 access points 32 access points 34 Access gateway 36 Access gateway 38 Access Gateway 40 Mobility Manager Server 42 Mobility manager register 44 application server