Selectable packet-switched and circuit-switched services in a mobile communications network

Method and apparatus for providing selectable packet-switched and circuit-switched services in a mobile communication network

FIELD OF THE INVENTION The present invention relates to mobile communications, and more particularly to different services and features that can be used to establish and enhance communications between a mobile station within a mobile communications network and an external network entity.

This application claims priority from US Provisional Patent Application No. 60/060,062, filed on September 25, 1997. This application is also related to commonly assigned US Patent Application No. 09/087,496, filed on May 29, 1998, the disclosure of which is incorporated by reference.

The primary application of most mobile wireless systems, such as the Global System for Mobile Communications (GSM), is in mobile phones that support only circuit-switched communications, which typically allows a fixed circuit to be dedicated to the user for the duration of the call. However, packet switching applications such as facsimile transmission and short message exchange are becoming popular in mobile networks. Examples of data applications include wireless personal computers, mobile offices, electronic funds transfer, road transport telemetry, field service businesses, fleet management. etc. These data applications are characterized by "bursty" traffic, in which a relatively large amount of data is transmitted during a relatively short time interval followed by a significant time interval in which little data is transmitted or no data is transmitted.

Although bursty traffic can be transmitted using circuit-switched channels, such transmissions do not disrupt the channel because there is a large gap between bursts when the channel is reserved but no information is sent from or received by the user when not in use. use less From an efficient point of view, this is a waste of transmission resources, which is particularly limited in wireless communication. However, from a customer service point of view, since the circuit-switched channel is not shared with other users, the user is essentially guaranteed a constant quality of service. In addition to inefficiencies, circuit switched channels require a relatively long time to set up and disassemble circuit switched calls compared to routing individual packets in a packet switched session. In bursty traffic conditions, the packet switched bearer makes better use of the transmission bandwidth because the communication resource is only used when there is data to transmit. A communication channel is thus generally shared by multiple users. Another advantage is that, as opposed to the time-based charging applied to circuit switched connections, packet switched data services charge according to the amount of data actually transmitted and the quality of the transmission service.

In order to provide such a mobile data application, the packet radio network service provides a radio packet switched data service with high bandwidth efficiency. One example is General Packet Radio Service (GPRS) integrated into existing circuit switched GSM networks. Another example is Cellular Digital Packet Data (CDPD) used in existing D-AMPS networks. The primary concern of end users of mobile packet data services such as GPRS is that wireless PCs support conventional Internet-based applications such as file transfer, submission and reception of e-mail, and Internet surfing through the World Wide Web. Conferencing and playback applications, including video and multimedia, are also important services to be supported by mobile networks.

Although circuit switched services are well known in mobile networks, mobile packet switched services are quite new. Accordingly, a brief description of a mobile packet switched service using GSM/GPRS as an example is now provided.

1 illustrates a mobile data service from the perspective of a user in the context of a mobile communication system 10 . The end user communicates the data packets using a mobile host 12 connected to the mobile terminal 16 , for example comprising a laptop computer 14 . Mobile host 12 may, for example, via a mobile packet support node 22 via one or more routers 24 , packet data network 26 and router 28 of private communications network 20 , via a local area network (LAN) communicates with a fixed computer terminal 18 incorporated in 20 . Of course, those skilled in the art will understand that the drawings are simplified as these paths are logical paths rather than actual physical paths or connections. In wireless data packet communication between mobile host 12 and fixed terminal 18, packets are independently routed from source to destination and do not necessarily follow the same path (which may be the case).

Thus, independent packet routing and transmission within the mobile network is supported by the mobile packet data support node 22 acting as a logical interface or gateway to the external packet network. A subscriber can transmit and receive data in an inter-terminal packet transmission mode without using any circuit switched mode network resources. In addition, multi-point parallel application is possible. For example, a mobile host such as a mobile PC can simultaneously run a video conferencing application, an e-mail application, a facsimile application, a web browsing application, and the like. Video conferencing applications generally require one or more data streams (hereinafter referred to as application flows).

2 shows in more detail a mobile communication system that supports both circuit switched and packet switched communications and uses an example of a GSM mobile communication model comprising a circuit switched network 35 and a packet switched network 51 . A mobile host 12, including a computer terminal 14 and a mobile radio 16, communicates with one or more base stations (BS) 32 via an air interface. Each base station 32 is located within a corresponding cell 30 . Multiple base stations 32 are connected to a base station controller (BSC) 34, which manages the allocation and deallocation of radio resources and controls handover of mobile stations from one base station to another. The base station controller and associated base station are often referred to as a base station subsystem (BSS). The BSC 34 is connected to a mobile switching center (MSC) 36 in the GSM circuit switched network 35, through which other networks 38 such as the Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN), etc. A circuit-switched connection is established to

The MSC 36 is also connected via a Signaling System 7 (SS7) network 40 to a Home Location Register (HLR) 42 , a Visitor Location Register (VLR) 44 and an Authorization Center (AUC) 46 . VLR 44 includes a database containing information about all mobile stations currently located in a corresponding location or service area, as well as temporary subscriber information needed by the MSC to provide service to mobile stations within that service area. Generally, when a mobile station enters a visited network or service area, the corresponding VLR 44 requests and receives data for the roaming mobile station from the mobile station's HLR and stores it. As a result, when the visiting mobile station is involved in the call, the VLR 44 already has the information it needs to set up the call.

HLR 42 is a database node that stores and manages subscriptions. For each home mobile subscriber, the HLR sets a Mobile Station ISDN Number (MSISDN) that uniquely identifies a mobile subscription in the PSTN number scheme and an International Mobile Subscriber Identifier (IMSI), a unique identifier assigned to each subscriber and used for signaling in the mobile network. ), including persistent subscriber data. All network related subscriber information is connected to the IMSI. The HLR 42 also contains a list of services the mobile subscriber is authorized to use according to the current subscriber location number corresponding to the address of the VLR currently serving the mobile subscriber.

Each BSC 34 connects to a GSM packet switched network corresponding to a GPRS network 51 at a serving GPRS support node (SGSN) 50 responsible for forwarding packets to mobile stations within its service area. A gateway GPRS support node (GGSN) 54 acts as a logical interface to an external data packet network, such as an IP data network 56 . The SGSN node 50 and the GGSN node 54 are connected by an IP backbone 52 in the PLMN. Thus, between SGSN 50 and GGSN 54, Internet Protocol (IP) is used as a backbone for transmitting data packets.

Within the GPRS network 51, packets or protocol data units (PDUs) are encapsulated at the originating GPRS support node and decapsulated at the destination GPRS support node. Such abbreviation/desummation at the IP level between the SGSN 50 and the GGSN 54 is called tunneling in GPRS. The GGSN 54 maintains routing information used in the tunnel PDU for the SGSN 50 currently serving the mobile station. The Common GPRS Tunnel Protocol (GTP) allows different sub-packet data protocols to be used even if they are not supported by all SGSNs. All GPRS user related data required by the SGSN to perform the routing and data transfer functions is accessed from the HLR 42 via the SS & network 40 . The HLR 42 stores routing information and maps each PDP address to one or more GGSNs as well as maps the IMSI to one or more Packet Data Protocol (PDP) addresses.

Before the mobile host can send packet data to an external network, such as the Internet Service Provider (ISP) 58 shown in FIG. 51), and (2) create a packet data protocol (PDP) context to establish a relationship with the GGSN 54 towards the external network being accessed by the mobile host. An association procedure is executed between the mobile host 12 and the SGSN 50 to establish a logical link. As a result, a temporary logical link identifier is assigned to the mobile host 12 . The PDP context is established between the mobile host and the GGSN 54 . The selection of the GGSN 54 is based on the name of the external network to be reached.

More than one application flow (often referred to as a routing context) may be established for a single PDP context through negotiation with the GGSN 54 . An application flow corresponds to a stream of distinguishable data packets as related to a particular host application. An example of an application flow is an e-mail message from a mobile host to a fixed terminal. Another example of an application flow is a graphic file downloaded from a web site. All of these application flows relate to the same mobile host and the same PDP context.

Packet switched data communication is generally based on specific protocol procedures that are separated into different layers. Figure 3a shows a GPRS transmission plane modeled as a multi-layer protocol stack (transmission plane). Between the GGSN and SGSN, the GPRS Tunneling Protocol (GTP) tunnels the PDUs through the GPRS backbone network 52 by adding routing information to encapsulate the PDUs. The GTP header contains a tunnel end point identifier (TID) for point-to-point and multicast packets, as well as a group identifier (GID) for point-to-point packets. Also included is a type field listing the quality of the service profile related to the PDU type and PDP context session. Under GTP, the well-known Transmission Control Protocol/User Diagram Protocol (TCP/UDP) and Internet Protocol (IP) are used as GPRS backbone network layer protocols. Ethernet, Frame Relay (FR0), or Asynchronous Transfer Mode (ATM) based protocols may be used for the link and physical layers depending on the operator's network architecture.

Between the SGSN and the mobile station/host, the Subnetwork Dependent Conversion Protocol (SNDCP) maps network level protocol properties to the lower logical link control (LLC), multiplexing, encrypting, segmenting and Provides functions such as compression. The Base Station System GPRS Protocol (BSSGP) is a flow control protocol that allows the base station system to start and stop PDUs transmitted by the SGSN. This prevents the BSS from flooding packets when the radio link capacity is reduced due to, for example, fading and other adverse conditions. Routing and quality of service information is also conveyed. Frame relaying and ATM can be used to relay frames of PDUs through the physical layer.

Wireless communication between a mobile station and a GPRS network covers physical and data link layer functions. The physical layer is divided into a physical link sublayer (PLL) and a physical RF sublayer (RFL). RFL performs modulation and demodulation of the physical waveform and specifies the carrier frequency, radio channel structure, and raw channel data rate. The PLL provides information transmission service over a physical radio channel, and includes data unit framing, data coding, and detection/correction of a physical medium transmission area. The data link layer is divided into two distinct sublayers. The Radio Link Control/Medium Access Control (RLC/MAC) sublayer coordinates access to a shared physical radio medium between multiple mobile stations and a GPRS network. RLC/MAC multiplexes data and signal information, and performs contention resolution, service control quality and error handling. The Logical Link Control (LLC) layer operates on the MAC layer and provides a logical link between the mobile host and the SGSN.

It is important to be able to provide the required quality for any particular communication service. For example, any multimedia application or simple voice phone call requires guarantees of accuracy, reliability and transmission speed. For packet-switched applications, "best effort" is generally used, and no special attention is required to guarantee latency or throughput. Typically, quality of service parameters will be characterized qualitatively into three service classes, including deterministic (used for hard real-time applications), statistical (used for soft real-time applications), and best-effort (all else not guaranteed). can Quantitative parameters include throughput (such as average data rate or maximum data rate), reliability, and jitter corresponding to the delay experienced by the message and the delay varying between the minimum and maximum delays.

In the context of providing quality of service (QoS) in a mobile data communication system, one QoS method is to assign a specific priority to each PDP context. However, this method is unsatisfactory. As described above, each PDP context may have multiple application flows, and each application flow may have different needs. For example, real-time applications, such as telephony, require guaranteed low-latency services, while image imaging requires predictable latency services. In particular, flexible applications such as interactive burst, interactive bulk transmission, and asynchronous bulk transmission require different degrees of best effort or possibly delayed services.

It is an important object of the present invention to provide wireless Internet access based on quality of service to support multiple application services including voice, data and multimedia where some of the applications may have multiple application flows running concurrently. In the case of Internet aggregation services, important quality of service factors are perceived transport link layer delay, jitter, bandwidth and reliability. Rather than limit the quality of service to a single PDP context, the present invention limits the quality of service for each individual application flow as described in this patent application and below. Furthermore, the present invention enables selection of a particular type of transport mechanism most suitable for transporting individual application flows according to quality of service requirements.

Typically, network technologies transmit data according to only one type of transport mechanism, either circuit switched or packet switched, even in GSM, which includes both circuit switched and packet switched networks sharing the same radio access interface. In the present invention, an optimal type of mobile communication network transport service, circuit switched transport service or packet switched transport service is specified based on individual application flows. Circuit switched services may be selected for real-time (low latency and small jitter) application flows such as audio and video, for example. Packet switched bearers can be selected for non-real-time Internet-like data applications such as surfing, file transfer, e-mail and telnet on the World Wide Web, all of which require high-speed channel access and bursty data transfer capabilities.

First, a mobile station registers with a mobile communication network to establish communication with an external network entity, such as an Internet Service Provider (ISP). During such communication, the application may initiate different data streams or flows of applications (hereinafter referred to as application flows) between the mobile station and an external network entity. For each application flow, a decision is made as to whether a circuit switched or packet switched bearer is to be established. The bearer carries or carries information from the mobile station to an external network entity via the mobile communication network, and carries information from the external network entity to the mobile station via the mobile communication network.

Each application flow may have a corresponding quality of service requirement. Based on the corresponding quality of service, a decision is made as to whether a circuit switched bearer or a packet switched bearer is more suitable for transporting the application flow. Application-specified quality of service parameters for individual application flows are mapped to corresponding quality of service parameters for the selected bearer, either circuit switched or packet switched bearers. Mobile communication resources and corresponding quality of service parameters for the selected bearer may be reserved in advance for each application flow (resource reservation method). Alternatively, the header of each information packet in the application flow may specify the class of service normally recognized when the read determines whether a circuit-switched bearer or a packet-switched bearer is carrying the packet (differential service method).

Several algorithms can be used to determine the type of bearer to be assigned to a particular application flow. For example, a determination may be made as to whether the application flow requires a real-time service or a non-real-time service. A circuit-switched bearer is allocated when the request is for a real-time service, and a packet-switched bearer is allocated when the request is for a non-real-time service. Other criteria may be used. For example, a circuit-switched bearer may be allocated if the application flow requires low latency or small jitter per packet, and a packet-switched bearer may be allocated if the application flow requires high-speed channel access or bursty data transmission capability. have. Another method may be to determine the flow duration and/or the amount of information to be sent out for each application flow. A circuit switched bearer may be allocated when a large amount of information is transmitted or when an application flow has a long lifespan. In other cases, a packet switched bearer is assigned.

For either bearer allocation method, it is desirable that the packet switched bearer be used to carry inherently bursty and simple control information, since it sets up and resolves the time provided by the packet switched bearer at a high speed (not necessarily necessary). no). On the other hand, if a circuit-switched bearer for the mobile station already exists in the application flow, the packet-switched information can be transferred to the existing circuit-switched bearer (since it already exists), although that information is more suitable for transmission over the packet-switched bearer. can be transmitted through This method is used, for example, in mobile stations that cannot determine circuit switched and packet switched traffic at the same time, eg, so-called class B GPRS mobile stations.

An important advantage of the present invention is that an application running on a mobile station or on an external network entity such as an Internet service provider can specify the required quality of service on the basis of an individual application flow, and with this information the application flows through the mobile communication network. It is possible to select the type of bearer to be used when transmitting . Since the application has the best end-to-end view of communication, the quality of service characteristics for the type of application flow and bearer/transport mechanism can both be chosen at an advantageous application layer.

The mobile station and the mobile network gateway node each include a mapper that maps the respective application flows to one of the circuit switched network and the packet switched network according to the quality of service required for the respective application flows. Quality of service parameters corresponding to individual application flows are also mapped to circuit switched parameters when the application flows are mapped to circuit switched networks, and to packet switched parameters when application flows are mapped to packet switched networks.

The gateway node includes a common access server that enables a mobile station to first establish a communication session with an external network entity to perform only a single common access procedure for subsequent communication using either a circuit switched network or a packet switched network. After the common access procedure is completed, a subsequent application flow between the mobile station and the external network entity is established without the need to execute another access procedure involving the external network entity.

The common access procedure includes a common authentication procedure for authenticating the identification of a mobile station by an external network entity. The mobile station is then authenticated for subsequent application flows by external network entities for both circuit switched and packet switched networks. The common authentication procedure includes a procedure for verifying the mobile station authentication and password to determine if the mobile station is authorized to communicate with an external network entity.

The common access procedure also utilizes a common configuration procedure for configuring the mobile station by an external network entity. The mobile station is then configured with an external network entity for both circuit switched and packet switched networks and a common network address for subsequent application flows. The common configuration procedure involves providing the mobile station with the parameters it needs to communicate with an external network entity, including the network layer address assigned to the mobile station. The configuration parameters are stored by the common access server so that, for a subsequent application stream accompanying the mobile station during the session, the common access server retrieves the stored parameters and configures the subsequent application stream without involving an external network entity.

By allowing individual application flows to individually select (1) quality of service parameters and (2) the type of transport mechanism (either circuit switched or packet switched bearer), the present invention provides better service for different types of applications. . At the same time, a common access procedure for all application flows within a session provides faster service. In practice, the authentication and configuration procedure between the mobile station and the Internet service provider takes approximately 20 to 30 seconds to execute when using a circuit switched bearer. This significant delay becomes even more inconvenient if such access procedures have to be executed for each of multiple application flows. Assume that the length of delay associated with the conferencing application requires the simultaneous execution of multiple application flows.

These uncomfortable delays are eliminated in the present invention. Upon mobile registration, the initial authentication and configuration procedure using the packet switched bearer is executed in less than 1/2 of the aforementioned 20-30 seconds. Even more time is saved because these initial authentication and configuration procedures are not executed for each subsequent individual application flow. Instead, the omitted authentication and configuration procedure is executed in a subsequent flow incorporated within the mobile communication network at a common access server in just a few seconds.

The foregoing and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments as shown in the accompanying drawings in which like reference numerals are used throughout the drawings. The drawings are not necessarily to scale and to explain the principles of the present invention.

1 is a schematic diagram illustrating data communication between a mobile host and a stationary host;

2 is a detailed diagram illustrating a GSM mobile communication system including a general packet radio service (GPRS) data network;

Fig. 3 shows an example of a data communication protocol used between different nodes within a packet switched GPRS data communication network in GSM;

4 is a flowchart illustrating an optimal bearer selection procedure per application flow according to an embodiment of the present invention;

5 is a protocol stack diagram illustrating an embodiment of mapping an application flow to a specific bearer according to a specific quality of a service parameter according to the present invention;

Fig. 6 shows an example of a data communication protocol used between different nodes in a circuit switched mobile communication network in GSM;

7 is a diagram illustrating several mobile application flows managed and mapped according to an embodiment of the present invention;

8 is a flowchart illustrating sample prioritization for selecting bearers and corresponding QoS bearer parameters of an application flow according to an embodiment of the present invention;

9 is a functional block diagram illustrating an embodiment of the present invention in a GSM/GPRS mobile communication system;

Fig. 10 is a messaging sequence diagram illustrating an example of an application flow in which circuit switched and packet switched bearer services are selected;

11 is a flowchart illustrating a common external network access procedure according to an embodiment of the present invention;

12 is a message sequence diagram illustrating an example of a common authentication procedure for circuit switched and packet switched services;

13 is a messaging sequence diagram illustrating an example of a common IP host architecture for circuit switched and packet switched bearer services;

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as specific embodiments, hardware, techniques, etc., in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from the specific details. For example, although certain embodiments of the present invention have been described in the context of a GSM/GPRS cellular telephone network, those skilled in the art will recognize that the present invention may be practiced in any mobile communication system using other mobile data communication structures and/or protocols. will understand In other instances, detailed descriptions of well-known methods, interfaces, apparatus, and signal techniques are omitted so as not to obscure the description of the present invention with unnecessary detail.

As already mentioned above, each application flow contains a corresponding stream of data. In order for a mobile station to communicate with an external network entity such as an Internet Service Provider (ISP), the mobile station must establish communication with the mobile communication network either by using a dial-out circuit switched connection or via an authenticated packet switched tunnel. The present invention uses a method of establishing communication with a mobile communication network via an authenticated packet switched tunnel to first establish an application session to avoid the setup time required for dial-out calls.

In the GSM/GPRS example, the mobile station registers with the mobile communication system and initiates a packet data protocol (PDP) context activation to initiate a data session. HLR 42 of Figure 2 stores the PDP context for each mobile subscriber in the corresponding subscription record. The PDP subscription record includes subscription quality of service profile/parameters, subscription external network, MSid such as IMSI (International Mobile Phone Subscriber Identification), etc. When a mobile station joins a GPRS network, the mobile station's subscription record is retrieved from the HLR 42. As a result of PDP context activation, a network layer bearer is established between the mobile station and a gateway GPRS support node (GGSN) 54 .

After PDP context activation, a network layer eg IP, host configuration operation is executed to establish network layer (IP) bearer communication between the mobile host and an external network entity such as an ISP. IP configuration includes assigning network layer (IP) addresses to mobile stations and setting default values for World Wide Web (WWW) servers, Domain Name Servers (DNS), Address Resolution Protocol (ARP) caches, and the like. When the IP bearer between the GGSN and the mobile host established at the time of PDP context activation is extended from the GGSN to the ISP, data packets can be routed back and forth between the mobile station and the end system of the ISP.

As mentioned above, one of the important objects of the present invention is to provide wireless Internet access based on quality of service to support multiple services including voice, data and multimedia at the same time. Internet applications may require quality of service specifying one or more of the following factors: perceived transport link layer delay, jitter, bandwidth and/or reliability. One or more of these quality of service factors depending on the value may be better provided by a particular type of bearer. Circuit switched bearers are more suitable for carrying real-time services such as voice and video that require low latency and/or small jitter. Traditional Internet data applications such as WWW, file transfer, e-mail and telnet are better served by packet-switched bearers better suited for high-speed channel access and bursty data transfer.

The present invention allows applications to select a specific quality of service and a specific type of mobile network transport mechanism (circuit switched bearer or packet switched bearer), rather than allowing applications to restrict all application flows to a single quality of service and/or single transport mechanism. It provides mobile subscribers with considerable flexibility and a wide range of services. 4 shows an optimal bearer selection routine (block 60). Here, it is assumed that the mobile station is already registered in the mobile network using, for example, the PDP context activation procedure described above.

After registration, a plurality of application flows are communicated between the mobile station and an external network entity, such as an Internet Service Provider (ISP), shown in FIG. An application (such as a multimedia circuit) requires one or more quality of service (QoS) parameters for one or more individual application flows (block 62). Based on the required quality of service for the particular application flow, an optimal one of circuit switched and packet switched bearers is selected to carry the particular application flow (block 64). The required quality of service parameters for each application flow, including, for example, maximum bit rate, bucket depth (maximum buffering demand for flow) and per packet delay are, for example, in the case of packet switched bearers, maximum throughput, burst size and delay class. is mapped to the bearer parameters of the selected bearer including (block 66). As a result, each application stream receives the optimal service in terms of quality of service parameters as well as the type of transport mechanism most suitable for carrying the type of information to be transmitted in a particular application flow.

Typically, a general application having a plurality of application flows requiring communication between a mobile station and an external network entity such as an ISP may follow the example procedure below.

(1) The mobile station registers using a common access procedure for both circuit switched and packet switched bearers communicating at the ISP using low cost packet switched bearers and full dynamic host configuration support. After that, only shortened authentication and configuration procedures are required for subsequent absolute application flows, as detailed below.

(2) A packet-switched bearer service with predictive quality of service delay class is used to transmit the application control message.

(3) A packet switched bearer service is used to transmit bulk data with best effort quality of service delay class.

(4) The low latency quality of the service provided by the circuit switched bearer service is used to transmit the audio or video component.

Figure 5 illustrates a protocol model that allows individual application streams to be individually serviced rather than serving a single application. The protocol structure shown in FIG. 5 may be implemented in a mobile station and in a mobile communication network gateway node, such as a GGSN in the GSM/GPRS example. Assuming that an application (such as a conferencing or playback application) contains control signals as well as multiple actual application flows, the application must create a quality of service application programming interface (AIP) for each application flow (including the control signal flow associated with the application). to request a corresponding quality of service. WinSock 2.0 or Win32 marketed by Microsoft is a choice for quality of service API.

Quality of service is mapped towards IP reservation protocols such as RSVP established by the Internet Engineering Task Force (IETF). Depending on the application flow characteristics, a reliable transport protocol (TCP) or an unreliable transport protocol (UDP) may be applied. The bearer/link selection and quality of service parameter mapping layer according to the present invention is configured to transmit RSVP quality of service requirements to either a circuit switched bearer supported by a circuit switched network in a mobile communication system or a packet switched bearer supported by a packet switched network in a mobile communication system. It is used to map to one.

When RSVP quality of service requests are mapped to circuit switched or packet switched bearers, quality of service parameters specific to each individual application flow are mapped to circuit switched or packet switched parameters depending on the bearer type selection. In circuit switched networks, such quality of service parameter mapping involves, for example, selecting an appropriate number of radio channels (eg, time slots in TDMA based systems, spreading codes in CDMA systems, etc.) to correspond to the required bandwidth. In packet switched networks, there are multiple options that are considered to support quality of service at different protocol layers.

A generalized group of quality of service parameters can be defined for a transport mechanism and is called a bearer quality of service profile. The bearer quality of service profile may be used to determine the quality of service in the radio link control layer, the logical link control layer, and the GPRS tunneling protocol (GTP) layer of the packet switched bearer of FIG. 3 in order to establish the quality of service between terminals. The radio link control layer is affected by packet delay and reliable quality of service parameters of the bearer quality of service profile, whereas the logical link control layer is affected by bit rate and priority/priority information. The GPRS tunneling protocol between the GPRS service and the gateway nodes SGSN and CGSN shall ensure that the tunnel does not violate any of the parameters in the quality of service profile. This demand is typically experienced because the radio link is the bottleneck of the mobile communication system architecture.

The corresponding layers in the circuit switched bearer of Figure 6 are the radio link protocol and the layer 2 tunneling protocol. A radio link protocol may allocate one or more time slots to a mobile station to allocate or change the bandwidth of a circuit switched connection. The radio link protocol provides additional selection of bearer service types within the scope of circuit switched bearers. The bearer service type may be optimized for voice, video or data, for example V.110 is optimized for data modems as shown in FIG. 6 . The type of bearer service (voice, video or data) in a circuit switched bearer can be seen as a poor quality of service identification compared to the individual QoS parameters for reliability, delay and rank as provided in packet switched link layer control.

The circuit switched layer 2 tunneling protocol has essentially the same rules as the GPRS tunneling protocol for packet switched bearers, which tunnels calls between the gateway node and the mobile switching center via the IP infrastructure. The layer 2 tunneling protocol's control phase contains all information about a normal GSM circuit switched call. In contrast to the GPRS tunneling protocol, which carries IP directly, the Layer 2 tunneling protocol carries IP packets as a point-to-point protocol (PPP). The addition of the point-to-point protocol is essential for fragmentation of packets, authentication of calls, and configuration functions of terminals already created in the GPRS tunneling protocol.

7 is a diagram illustrating a specific mobile application in which three exemplary application flows include a video application flow, an audio application flow, and a conference application flow (a total of four application flows) along with a system control operation flow. Each flow has a quality of service associated with that recognized at the IP layer. At the transport layer, each application flow uses a different coding and messaging protocol than the appropriate one. Video and audio application flows are generally processed through a codec, such as H.263/H.261 for video or GSM 06.10 for audio, and summarized in Real Time Transport Protocol (RTP) for end-to-end delay-sensitive transmission. Application flows containing control data for application sessions, such as conference sessions, do not require codecs, but instead use Real-Time Session Control (RTSP), Session Request (SIP), and Session Announcement (SAP) protocols. These protocols are further abbreviated as UDP or TCP to create an entire transport layer. The final application flow relates to system control and follows the transport protocol for coordinating resource reservations of other flows such as RSVP and dynamic configuration of mobile stations such as DHCP.

Rather than using a multiplexer eg H.223 that multiplexes all four application flow types for transmission by one type of bearer eg a circuit switched bearer such as a V.110 modem, the present invention provides circuit switched bearers and packet switched It provides the bearer selection and quality of service parameter map layer layer that selects the most suitable one of the bearers for each application flow at the IP layer. In this exemplary diagram of FIG. 7, the circuit switched bearer is shown as a V.110 modem using the IP/PPP protocol, and the packet switched bearer is shown as a GPRS modem using the IP over SNDCP protocol. Circuit switched modem connections are established by dialing a phone number to establish a dedicated connection where individual IP packets are not routed. Point-to-Point Protocol (PPP) is used to carry IP packets over any serial line, dial-up connection and is more suitable for circuit switched bearers. Conversely, the GPRS modem routes each IP packet based on its header information. Subnetwork Dependent Conversion Protocol (SNDCP) provides segmentation and compression of data and headers between the mobile station and the SGSN of GPRS. SNDCP is specifically developed to prevent PPP by carrying IP packets directly.

In a preferred and particular embodiment of the present invention, selection of a particular type of bearer and mapping of quality of service parameters is as described now with respect to a bearer selection and QoS map routine (block 70) shown in the functional block format of FIG. The same may be implemented according to different prioritization criteria. First, individual application flows are detected together with corresponding application flow identifiers or associated quality of service classes. In the resource reservation embodiment, individual application flows may specify and reserve the required IP level quality of service parameters in advance. Alternatively, in the differential service embodiment, a new predefined service class may be combined with an individual application flow; All packets in the application flow are processed according to the quality of service class. The resource reservation method allows great reliability to select different IP level quality of service parameters. Differential service methods, predetermined quality of service parameters associated with each general service class are easier to manage.

Some of the specific IP level quality of service parameters may be provided higher than the remaining parameters. For example, at block 74, a determination is made whether the IP quality of service parameter corresponding to the packet delay is absent or present, if the parameter is within, below, or above a threshold (T) range. In this example, the delay is the highest provided parameter. If the delay parameter is present and above the threshold, a new packet switched (PS) bearer is established. If a packet switched bearer has already been established, the existing packet switched bearer may be changed to adjust the newly detected delay parameter (block 84). Accordingly, the IP quality of service parameter is mapped to the packet switched bearer quality of service parameter. On the other hand, if the associated delay parameter is below the threshold range, a new circuit switched (CS) bearer is established or an existing circuit switched bearer is changed to adjust the newly detected delay parameter (block 86). Similar to the mapping function of block 84, the IP required IP quality of service parameters are mapped to the corresponding circuit switched bearer quality of service parameters.

Thus, if the application flow can tolerate large delays, a packet switched bearer is selected. If the delay is slightly tolerated or cannot be tolerated at all, a circuit switched bearer is selected. However, if the detected delay parameter is within or absent a threshold range, then a subsequent lower priority quality of service parameter, in this example bucket depth (corresponding to the size of the buffer required to store the message being sent), is absent, within the threshold range, less than or equal to or any of the above is determined. If the bucket depth exists and is greater than or equal to the threshold range, a packet switched bearer function is selected (block 84). If the bucket depth is less than or equal to the threshold range, a circuit switched bearer procedure is selected (block 86). Bucket depth may be similar to the burstiness quality of the application flow. Very bursty application flows are more appropriately carried by packet switched bearers. Conversely, application flows with little or no burstiness (ie, continuing) are more suitable for circuit switched bearers.

If the bucket depth parameter is absent for that application flow or is within a threshold range, another determination is made at block 78 whether the class of service is specific to this particular application flow. If a best effort class of service is specified, a packet switched bearer is selected according to the procedure of block 84. If a guaranteed class of service exists, at block 86 a circuit switched bearer procedure is selected. However, if the service class is not specified or there is a "control load" (ie, something between best effort and warranty type of service), then at block 80 the time-to-live (TTL) parameter is A determination is made of whether absent, within, below, or above a critical range. If the application has a short time-to-lifetime, a packet-switched bearer is selected according to the procedure of block 84 to clear the connection setup time associated with the circuit-switched bearer and communicate data before its lifetime expires. On the other hand, if the time-to-lifetime parameter is greater than or equal to the threshold range, the circuit-switched bearer is selected according to the procedure highlighted in block 86, since the application flow has a lifetime sufficient to wait for the circuit-switched bearer to be established.

If the time versus lifetime parameter is absent or within a threshold range, then at block 82 a determination is made whether the application flow volume (which may be determined by multiplying the time versus lifetime parameter and the average bit rate (MBR)) is absent, within, below, or above the threshold range. this is done If the flow volume is below the threshold range representing a significantly small volume, then the packet switched bearer is more optimal and block 84 is selected. Alternatively, if there is a large data volume, it is more optimal to select a circuit switched bearer according to the procedure of block 86. For simplicity of explanation, a default decision is made to select a packet switched bearer if the volume is within or absent from a threshold. Of course, those skilled in the art will understand that other quality of service parameters may be queried in a similar manner.

Blocks 84 and 86 both represent mapping of quality of service to specific bearer quality of service parameters. An example of a mapping of IP quality of service (QoS) parameters to packet switched QoS parameters (as used in GPRS) is as follows:

IP QoS parameters PS QoS parameters

Maximum Bitrate Maximum Throughput

Average Bitrate Average Throughput

Time-to-Lifetime (TTL) Average Throughput

Bucket Depth Burst Size

Total Packet Delay Latency Rating

Service class Reliability class

service class rank rank

A similar quality of service mapping example is provided for circuit switched bearers:

IP QoS parameters CS QoS parameters

Class of service bearer service type

Maximum number of bitrate time slots

Average Bitrate Number of Time Slots

Reference is made to FIG. 9 illustrating a mobile communication system in a functional block format based on an example of GSM/GPRS in which an embodiment of the present invention is used. The mobile communication system 9100 includes a mobile station 102 including a dynamic host configuration protocol (DHCP) client 104 , a point-to-point protocol (PPP) client 106 , and a bearer selection and quality of service parameter mapper 107 . . The mobile station 102 is connected to a base station subsystem (BSS) 108 via an air interface (via circuit switched and/or packet switched bearers). The BSS includes a base station in communication with a mobile station coupled to a base station controller. 2, the base station controller of the BSS 108 routes circuit switched communications from the GSM circuit switched network 35 to a direct access unit (DAU) 102 within the MSC 110 via a circuit switched bearer. and routes packet switched communications from the GSM packet switched (GPRS) network 51 to the SGSN 114 via a packet switched bearer. The direct access unit 102 terminates the radio link protocol and V.110 modem calls. When instructed by the HLR carried over the MSC, the DAU 102 creates a layer 2 tunnel towards the GGSN. The DAU 102 uses subscription information retrieved from the HLR, such as the external entity phone number and the mobile phone's IMSI, to determine a specific GGSN to establish L2TP.

For calls originating from the mobile station, selection of a network and network bearer for application flows originating from the mobile station 102 are made by the mapper 107 of the mobile phone. The circuit switched bearer is transmitted to the external network gateway node corresponding to the GGSN 116 in the embodiment using the IP/PPP/L2TP protocol. An IP tunnel is created on a V.110 modem connection terminated by a direct access unit. The term "Layer 2 Tunnel Over IP" means that the L2TP protocol carrying the IP traffic between terminals also uses the lower IP network as a transport mechanism between the direct access unit and the GGSN.

Packet switched application flows are transmitted using DHCP/IP/GPRS tunneling protocol. DHCP is only applied at configuration time. Subsequent IP packets (after configuration) are carried directly on the GPRS bearer. The GPRS Tunneling Protocol (GTP) encapsulates the IP packets between the terminals between the service and the gateway node, and similarly to L2TP, it uses the lower IP network as the transport mechanism between the GPRS service and the gateway node. Therefore, circuit switched and packet switched data from MSC 110 and SGSN 114 to GGSN 116, respectively, are all by IP tunnel. The use of IP as a transport mechanism provides a flexible and scalable implementation of a mobile communications backbone using the Internet as a base.

GGSN 116 is similar to common access server 118, configuration relay agent 120, PPP server 122, L2TP server 124, RTP translator 126 and mapper 107 shown in mobile station 102. It includes a mapper 128 . The common access server 118 is managed interfaces to external network entities and uses a remote authentication protocol such as RADIUS to interact with external network entities when mobile station communications are permitted or denied to reach their destinations on the external network. . The RADIUS protocol (or other security negotiation protocol) may be used to match the external network entity with the security measure for the transport mechanism between the common access server within the GGSN and the entry point at the external network entity.

The configuration relay agent 120 relays DHCP messages between the DHCP in the mobile station and the DHCP server in the external network at configuration time. The configuration relay agent 120 specifically obtains the IP address assigned to the mobile station and uses that address for subsequent configuration of other mobile communication bearer services, for example via PPP. The configuration relay agent 120 also adds a security measure to the configuration by applying an identifier check to all information between the DHCP client and server.

The PPP server 122 terminates the established PPP link from the mobile station to the GGSN through a circuit switched mobile communication bearer. Specifically, PPP server 122 terminates authentication and configuration requests from mobile stations for circuit switched bearers, and uses information from common access server 118 and configuration relay agents 120 to respond to requests from mobile stations. .

The L2TP server establishes and terminates the virtual call over the IP network between the GGSN and the direct access unit 112 of the MSC 110 . The virtual call contains the same information and has the same duration as the real circuit switched call between the direct access unit 112 and the mobile station. The RTP translator 126 executes the translation of the coding rules between the coding scheme applied to the high-speed network between the GGSN and the external network entity and the coding scheme more optimally suited to the low-speed wireless network of the GSM. The RTP translator 126 may be provided with a user profile for each mobile phone user, eg, via RADIUS, to perform RTP translations suitable for a particular mobile station. The TTP translation function increases the likelihood that two entities can communicate with each other.

The mapper 128 performs link layer selection and QoS mapping functions per individual application flow. In particular, as described above, the mapper 128 determines whether the application reservation request is mapped to a circuit switched or packet switched mobile communication bearer, and translates the quality of service parameters from the application view to the mobile communication bearer view. However, the mapper may change the link layer bearer selection per packet under certain circumstances.

One such situation is a circuit switched connection where a class B mobile station has already been established, and during such a circuit switched connection also receives packet data. As mobile data communications evolve, there may be different classes of mobile stations with different functions. For example, GSM currently defines three different classes of mobile stations: Class A, Class B, and Class C. A Class A mobile station may simultaneously generate and/or receive traffic on both circuit switched and packet switched bearers. Class B mobile stations support simultaneous activation and monitoring of circuit-switched and packet-switched services, but can only transmit or receive traffic corresponding to application flows on one type of bearer at a time. Class C mobiles are the least flexible and only support sending and receiving traffic on one type of bearer. In a situation where a Class B mobile has established a circuit-switched connection, mapper 128 transmits data over this same circuit-switched bearer rather than waiting to establish a packet-switched bearer when the circuit-switched bearer is released.

The GGSN 116 connects with an Internet Service Provider (ISP) using IP tunneling or link layer persistent virtual circuits. IP tunneling is preferred from a scale-out perspective where an IP tunnel must be configured at the end of the tunnel, i.e. to the GGSN and external network entities, but a persistent virtual circuit must also be configured at each intermediate node. However, in some cases, the built-in security of asynchronous transfer mode (ATM) and frame relay (FR) persistent virtual circuits may be prioritized compared to the more flawed IP tunnels.

The Internet service provider includes an authentication server 132 , a configuration server 134 , and a conferencing server 136 . An example of an authentication server assumed for illustrative purposes only is Remote Authentication Dial-in User Service (RADIUS), a protocol for authentication, authorization, configuration, and accounting between GGSN's Common Access Server 118 and ISP 130 . An example of a configuration server used in the description below is a DHCP server that transfers configuration information between hosts in a TCP/IP network. An example of an application server used in the description below is the conferencing server 136 acting as a gatekeeper for the entire conference. The gatekeeper conferencing server 136 maintains a record of who is participating in the conference and the types of application flows.

Both packet-switched and circuit-switched bearer services share the same accounting relationship with the same ISP. For example, a RADIUS server maintains a single data record for a mobile station. The data record accumulates accounting information for both types of bearer services that are keyed to an accounting record identifier corresponding to the MSid of the mobile station.

Fig. 10 shows an example of message signaling between several nodes of the communication system shown in Fig. 9 in which an optimal circuit switched or packet switched bearer service is selected for different application flows; It is assumed that an ISP relationship has already been established between the mobile station and the ISP conferencing server, and the mobile station has already received some application control packets via a packet switched bearer. In this example, the ISP conferencing server 9136 is the GGSN of the mobile communication system. Sends an IP packet corresponding to the real-time application flow from the conference toward the mobile station, which is received by The GGsN selects an optimal packet-switched or circuit-switched bearer and other parameters such as coding and/or compression ratio.

In this example, the RTP translator 126 in the GGSN 116 changes the coding of the stream from the high-speed conferencing server 136 to the low-speed mobile communication network based on the current RTP coding shown in the mobile station profile and packet header. . Based on the real-time characteristics of the incoming flow, a circuit switched bearer is established. The mobile station profile may be configured to be manageable, may be set by an authentication (RADIUS) server, or may be defined by some other user interface. The GGSN uses the mobile station profile to select the optimal coding and bearer service for each application flow as described above in FIG. 8 . GGSN uses mobile station class with bearer service type to switch between packet switched and circuit switched bearer service for class B mobile stations.

Referring to Fig. 10, in response to the real-time IP packet received from the ISP conferencing server, the GGSN starts a packet switched application flow through GTP or a circuit switched application flow through L2TP according to optimal bearer selection. The GTP protocol between SGSN and GGSN is extended with MS class parameters that allow the GGSN to determine whether a mobile station is a class A, B or C mobile station. As mentioned above, the GGSN applies special rules for class B mobiles.

Assuming that the circuit switched bearer is selected based on the real-time characteristics of the incoming packet, the GGSN is an L2TP outgoing call containing the dialed phone number corresponding to the MSid (the mobile station being called in this example), the call ID and the circuit switched bearer service type. send a request The circuit switched virtual call is received by the direct access unit 112 at the mobile switching center establishing a circuit switched call with the mobile station over the wireless link.

In this example, circuit switched bearers are established, but the GGSN associates IP packets from non-real-time application flows with real-time traffic flows. These NRT packets are more suitable for packet switched bearers, but GGSN sends IP packets along already established circuit switched bearers because the mobile station is a class B mobile station and can only support one type of bearer at a time. Non-real-time packets (i.e., protocol data units (PDUs)) are sent out as point-to-point protocol frames via an L2TP tunnel on a circuit switched bearer to a direct access unit at the MSC that relays the PDU to the mobile station over a circuit switched type radio link.

The mobile station decides to end the call and releases the circuit switched bearer. The mobile station sends a detach notification message through the direct access unit via the L2TP tunnel to the GGSN which affects the release of the circuit switched bearer. Then, the ISP conference server sends a non-real-time IP packet toward the mobile station. Since no existing circuit-switched bearer exists, the GGSN decides that the packet-switched bearer service is more optimal for non-real-time type packets and establishes a packet-switched bearer to carry the packet to the mobile station. Specifically, a packet switched tunnel is established between GGSN and SGSN via a GTP tunnel that carries IP packets with corresponding tunnel identifiers (TIDs). The SGSN establishes a logical data link (Logical Link Control (LLC)) between the SGSN and the mobile station, and forwards packets to the mobile station based on best effort.

One of the important advantages of the present invention is the use of a common access procedure for both circuit switched and packet switched bearer services between the mobile station and the Internet service provider. This common access procedure is implemented using a low-cost packet switched bearer, and includes a common authentication procedure and a common configuration procedure. After the common access procedure is completed upon initial registration, subsequent application flows are authenticated and configured using a very simple procedure that does not require contact with the ISP.

11 illustrates an example procedure for a common external network access routine (block 170) in accordance with another aspect of the present invention. When the mobile station establishes a session with the mobile communication network, only one common access procedure is executed to provide the mobile station access to both circuit switched and packet switched services (block 172). In particular, only one authentication procedure is executed using one or more authentication parameters, such as MSid, userid, password, etc., and the results from this procedure are stored for subsequent use (block 174). The common access procedure also includes executing only one ISP-mobile station host configuration procedure for both circuit switched and packet switched bearer services with the resulting configuration parameters also saved for subsequent use (block 176).

As described above, a mobile network bearer of the most suitable type is selected for each application sequence using the dynamic reservation method or the differential service method (block 178). In dynamic reserved access, communication resources such as radio channels are reserved in advance for a selected bearer, which provides QoS parameters specifically required for the bearer. In differential service access, each packet header is analyzed to determine whether the header describes one of a number of common classes of service as indicating transmission by a circuit switched bearer or by a packet switched bearer. Dynamic reserved access is preferred in this embodiment. In the next application sequence involving the mobile station, the stored authentication and configuration parameters are used to perform shortened (fast) authentication and configuration without the need to involve an external network entity (block 180).

The common external network access procedure has the advantage that it is performed only once for every application after completing the initial recording. The above common authentication and configuration procedure is performed using a packet switched bearer in less than half the time required for a normal write procedure using a circuit switched bearer. It saves even more time because the initial authentication and configuration procedure does not have to be performed for each subsequent application sequence. Instead, it performs shortened authentication and configuration on a common access server in mere seconds for the next sequence within the mobile communication network.

A common authentication procedure is now described with respect to FIG. 12 , which illustrates an exemplary message exchange between the multiple nodes of FIG. 9 . Assuming that the PDP context is requested by the mobile station and generated and accepted by the GGSN, the mobile station also initiates a common dynamic host configuration procedure (interleaved with the common authentication procedure), the mobile station's unique identifier (MSid). , establishes a logical relationship to the GGSN by sending a DHCP discovery message providing the user identifier (Userid), password, and other parameters that can be used to identify and authenticate the mobile station.

The GGSN maps the DHCP authentication request to the radius request by selecting the radius authentication server 132 of the ISP 130 formed in the user identifier if the user identifier is in the form of User@ISP. If not, the GGSN uses a static mapping of the user to the ISP. Assuming that the transmitted information is authenticated, the radius server 132 sends an access permission message with the tunneling configuration information to the common access server of the GGSN. The GGSN uses the tunneling configuration information to transmit a common host configuration message and other packets to the ISP. The GGSN stores the MSid, userid, and password of the mobile station, and proceeds to the common host configuration procedure, which will be described in more detail below. At this time, a common authentication procedure with the ISP is made for both circuit switched and packet switched bearer services.

Referring also to FIG. 12, suppose that a mobile station selecting a circuit switched bearer initiates a new application sequence (eg, a so-called voice call from mobile station (party A) to party B). The direct access unit 112 of the MSC 110 receives the modem connection corresponding to the circuit switched bearer selected for the new application sequence. The direct access unit 112 analyzes the B phone number of the called party and selects an appropriate GGSN connecting the B number and the L2TP by the HLR subscription information, ie, the call to B. Then, the direct access unit 112, in the form of a password authentication protocol (PAP) or a challenge authentication protocol (CHAP) request, is a common access server in the selected GGSN shown in the embodiment of FIG. 12 . transmits the authentication request to the mobile station to pass the mobile station authentication parameters including the MSid, the userid, and the password to the common access server.

Rather than performing another authentication procedure involving an external ISP, the MSid, userid, and password received in the PAP/CHAP request are compared against the values stored in the common access server during the initial authentication procedure. If the received value matches the value stored in the access server, an authentication confirmation is sent to the mobile station as a CHAP/PAP response through the direct access unit of the MSC. The common access server, consistent with the information provided above, authenticates the mobile station without the need to perform another authentication procedure with the ISP's radius server. A shortened authentication procedure of the same type is performed for other application sequences disclosed during the above procedure.

The common access procedure also provides a common IP host configuration procedure for both circuit switched and packet switched services, which will be described with respect to the signaling procedure shown in FIG. 13 . The IP host configuration is straightforward for the bearer setup except that it includes the DHCP configuration relay agent 120 of the GGSN. The DHCP relay agent 120 acts as an intermediary between the DHCP client 104 of the mobile station 102 and the DHCP server 134 of the ISP 130 . The relay agent 120 fixes the message transmission between the DHCP client 104 and the server 134 by adding an agent identifier (corresponding to the MSid) to each DHCP message sent to the DHCP configuration server 134 of the ISP. . The configuration relay agent 120 then uses the agent identifier to filter packets from and to the mobile station that do not have the correct IP address in the header and terminate. The agent remote identifier (remote ID), subnet mask, and gateway IP address (giaddr), which is an address identifying the GGSN, are transmitted to the ISP 130, which is checked and stored.

The ISP 130 determines a reply path to the GGSN using the subnet mask and the gateway IP address, and then sends the reply to the mobile station by the agent remote ID. The agent remote ID also provides additional authentication of the ISP that the mobile station does not manipulate its verification during the dynamic host configuration procedure. Accordingly, according to the above common authentication procedure, the configuration relay agent 120 adds the IP address of the GGSN to the gateway IP address field, and transmits the DHCP discovery message to the DHCP server.

The ISP's DHCP server 134 responds to a discovery message with a provisioned message forwarded by the GGSN to the mobile station containing a "provided" configuration that the DHCP server 134 can provision (after checking the incoming and outgoing tunnel identifiers). ). It can receive multiple offers from various DHCP servers. The mobile station chooses a DHCP offer that best meets that need and sends a DHCP request message to a DHCP server with the selected offer. Next, the DHCP server provides the IP address as GGSN in the DHCP Acknowledgment message. The IP address is placed in a table along with the mobile station's agent remote ID and agent circuit ID/tunnel identifier.

The DHCP acknowledgment message is forwarded to the mobile station host, which consists of a selected set of DHCP parameters including an IP address, DNS server name, and the like. The GGSN's common access server also stores said configuration parameters, such as the IP address assigned to the mobile station, along with authentication parameters such as MSid, userid, password, and the like.

Since the circuit switched and packet switched bearer services share the same IP destination/IP address of the mobile station, a common IP host configuration made on the packet switched (GPRS) bearer service is the next circuit switched from the same mobile station using the circuit switched bearer service. Includes PPP courses. When the mobile station initiates a new application sequence by sending a PPP configuration request to the GGSN over the L2TP tunnel on the circuit switched bearer, i.e. on the circuit switched bearer in the example shown in Fig. 13, the common access server includes the MSid and default configuration parameters. The PPP configuration request parameter is compared with the stored DHCP configuration information, and if the comparison result is consistent, an acknowledgment is returned. No further configuration action with the ISP DHCP server is required. After this shortened configuration procedure, the common access server only returns a PPP configuration acknowledgment to the mobile station via the direct access unit, and the selected circuit switched bearer starts transmitting the desired information.

The present invention combines both circuit switching and packet switching, providing an improved and effective application to the end user at a lower cost. Both circuit-switched and packet-switched services can be used when it is most appropriate for the respective application sequence. In addition to this, the present invention provides a common access procedure for accessing external network entities, such as ISPs, at a much lower cost and with significantly shorter setup times. Initial authentication and configuration procedures between common access servers at the gateway node are performed only once during initial storage and are effective for both circuit switched and packet switched bearer services. Therefore, only a shortened authentication and configuration procedure is required between the mobile station and the common access server in the next new application sequence.

Although the present invention has been described with respect to certain embodiments, it will be appreciated by those skilled in the art that the invention is not limited to the specific embodiments described herein. The present invention may also be embodied using various variations, modifications, and arrangements, as well as other forms, embodiments, and applications other than those shown and described above. For example, instead of the GSM circuit switched network described above, a wireless local area communication network (WLAN) or digital audio/video broadcasting (DAB/DVB) may be used. Likewise, other packet switched networks may be used. Accordingly, while the present invention has been described in terms of preferred embodiments, it is to be understood that the foregoing disclosure is merely illustrative of the present invention and is intended to provide a preferred and possible disclosure of the present invention. Accordingly, it is intended that the invention be limited only to the spirit and scope of the claims appended hereto.