Interworking apparatus and method for accepting IP in WCDMA system

An interworking apparatus includes an IP sending/receiving unit coupled to an IP network, an AAL2 sending/receiving circuit coupled to a WCDMA network, and a data processing circuit between the IP sending/receiving unit and AAL2 sending/receiving unit. The data processing circuit processes data in a format suitable for interworking between the WCDMA network and IP network.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to communication systems, and more particularly to an apparatus and method for performing an interworking function between at least two networks.

2. Description of the Related Art

Many networks differ in terms of their communication protocols. For example, in a wideband code division multiple access (WCDMA) network, voice and/or video data is forwarded to an AAL2 (ATN adaptation layer 2) cell. In an IP network, voice data is forwarded using a voice over IP (VoIP) service, where IP stands for Internet Protocol. VoIP is a term used in IP telephony for a set of facilities that deliver voice information using an Internet Protocol. Typically, this involves sending voice information in digital form in discrete packets, rather than according to traditional protocols of, for example, a public switched telephone network (PSTN).

FIG. 1is a diagram of a typical VoIP network. As shown, a codec and IP connection device are connected to the IP network. In such a configuration, signals (e.g., voice or fax) are processed in a data format compatible with the IP network and then are sent through the IP network. The codec encodes voice or fax data into packets having a predetermined length in one direction, and decodes packetized data into voice or fax data in a reverse direction.

In one direction, the IP connection device (A) sends the data packetized in the codec over the IP network to another IP connection device (B) performing a VoIP function. In the reverse direction, the IP connection device (A) receives packets from the other IP connection device (B) over the IP network and forwards them to the codec.

FIG. 2is a diagram of an AAL2 in a WCDMA system. As shown, a codec and an AAL2 (ATM adaptation layer Type 2) data processor are connected to a WCDMA network. In such a configuration, voice and/or video signals are processed in a data format compatible with the WCDMA network and then sent through the WCDMA network. In this system, the codec encodes voice and/or video data into packets of a predetermined length for transmission on the network, and decodes packets received from the network into voice and/or video data.

The AAL2 data processor assembles data from the codec into an AAL2 cell, and then forwards the cell for transmission over the WCDMA network. When an AAL2 cell is received from an AAL2 data processor of another station, it is disassembled into data packets, and then the codec decodes the packets back into voice and/or video data.

From the foregoing discussion, it is therefore apparent that each communication network performs data transmissions based only on their own protocols. That is, a VoIP network can implement voice service only with terminals that can access that VoIP network. Similarly, a WCDMA network can implement voice and/or video services only with terminals that can access that WCDMA network. There is no provision that will allow voice or data service to be provided through VoIP and WCDMA networks. Thus, when it is desirable to send data (e.g., voice, fax, video, etc.) from one type of network to another, no compatibility exists between the networks to do so.

SUMMARY OF THE INVENTION

Another object of the present invention is to provide an interworking apparatus and method for providing communications between a WCDMA network and an IP network.

To accomplish these and other objects and advantages, the present invention provides in accordance with one embodiment an interworking apparatus for accepting an IP in a WCDMA system, comprising: an AAL2 sending/receiving unit for sending and receiving data between a WCDMA network and a data processing unit; a data processing unit for processing data in a format suitable for interworking between the WCDMA network and the IP network; and an IP sending/receiving unit for sending and receiving data to/from the data processing unit and the IP network.

Preferably, the data processing unit comprises: an AAL2 processing unit for separating CPS packets from an ATM payload and assembling the CPS packets into the ATM payload; a UP protocol processing unit for adding or removing an UP protocol header to or from data of the CPS packet payload; an RTP processing unit for adding or removing a RTP header; and an IP processing u nit for adding a UDP header and an IP header to data inputted from the RTP processing unit and removing the UDP header and the IP header from data inputted from the IP processing unit.

In accordance with another embodiment, the present invention provides an interworking method for accepting an IP in a WCDMA system, in which data is sent and received from a first WCDMA network to an IP network, according to the present invention, comprising the steps of: (a) including a UDF in data and sending the same to a WCDMA network; (b) changing the header of the data and delivering the data; (c) delivering the data processed by separating CPS packets from an ATM payload; (e) delivering the data processed by adding a RTP header to the processed data; (f) delivering the data processed by adding a UDP header and an IP header to the processed data; and (g) forwarding the data processed by adding an Ethernet header to the processed data to the IP network.

Preferably, in the case that data is sent and received to a second WCDMA network from the first WCDMA network via the IP network, the interworking method further comprises the step of (d) delivering the data processed by adding a UP protocol header to the processed data between the step (c) and the step (e).

Preferably, in the case that data is data is sent and received to a second WCDMA network from the first WCDMA network via the IP network, the interworkign method further comprises the steps of: (h) receiving the data passed through the IP network; (i) delivering the data processed by removing the Ethernet header from the received data; (j) delivering the data processed by removing the UDP header and the IP header from the processed data; (k) delivering the data processed by removing the RTP header from the processed data; (l) delivering the data processed by removing the UP protocol header from the processed data; (m) delivering the data processed by assembling CPS packets in to the ATM payload; (n) changing the header in the data format and delivering the data; and (o) including a UDF in the data and sending the same to the WCDMA network.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with one embodiment, the present invention processes the format of data in two networks to achieve an interworking function between the networks. The two networks are preferably a WCDMA network and an IP network. In one way, the present invention may implement this interworking function by supporting the Support mode of a UP (user plane) protocol for accepting voice or video within an IP and converting the voice or video's UP (refer to 3GPP TS 25.415) data into an AAL2 (ATM adaptation layer Type 2) cell, which is a basic data format of the system. Other techniques may also be performed in accordance with the present invention.

FIG. 3shows an interworking apparatus between a WCDMA network and an IP network according to one embodiment of the present invention. This interworking apparatus300processes data for interwoking between a WCDM network and an IP network. The apparatus includes an AAL2 sending/receiving unit310, a data processing unit320, and an IP sending/receiving unit330. The AAL2 sending/receiving unit sends and receives data between the WCDMA network and the data processing unit320. The data processing unit320processes data in a format suitable for interworking between the WCDMA network and the IP network. And, the IP sending/receiving unit330sends and receives data to/from the data processing unit and the IP network.

The data processing unit320comprises an AAL2 processing unit321, a UP protocol processing unit322, a RTP processing unit323, and an IP processing unit324.

The AAL2 sending/receiving unit310sends and receives data of an ATM data format including a UDF (user define field) to and from a WCDMA system, and sends and receives data of the ATM data format whose header is changed to and from the AAL2 processing unit321.

The AAL2 processing unit321separates CPS (common part sublayer) packets from the ATM payload of the data received from the AAL2 sending/receiving unit310, or assembles CPS packets from the data received from the UP (user plane) protocol processing unit322into the ATM payload.

The UP protocol processing unit322adds a UP protocol header to the data of the CPS packet payload received from the AAL2 processing unit321, or removes the UP protocol header from the data received from the RPT processing unit323.

The RPT processing unit323acquires RTP header information from the connection ID of the data received from the UP protocol processing unit322to add a RTP header, or removes the RTP header from the data received from the IP processing unit324.

The IP processing unit324adds an UDP header and an IP header to the data received from the RTP processing unit323, or removes the UDP header and the IP header from the data received from the IP sending/receiving unit330.

The IP sending/receiving unit330adds an Ethernet header to the data received from the IP processing unit324to send the data to the IP network, or removes the Ethernet header from the data received from the IP network to send it to the IP processing unit324.

The interworking apparatus300processes and delivers data from a WCDMA network to an IP network, and on the contrary, processes and delivers data from the IP network. The interworking apparatus also processes and delivers data from the IP network to the WCDMA network. Further, the interworking apparatus may also interwork between the WCDMA network and the IP network, for the purpose of processing and delivering data from one WCDMA network to another WCDMA network via the IP network.

Hereinafter, the functions and operation of interworking apparatus300will be described with reference to the accompanying drawings. The description will be made with respect to the format of data processed in a series of components of the interworking apparatus.

As illustrated inFIG. 3to deliver data (e.g., voice or video) from a subscriber of a first WCDMA network to a subscriber of an IP network, first the data included in the payload field of an AAL2 (ATM adaptation layer type 2) is packetized and delivered to the AAL2 sending/receiving unit310. Here, the AAL2 cell refers to the format of ATM data sent and received in the WCDMA network.

The AAL2 sending/receiving unit321receives from the WCDMA network data added with a UDF (user define field) in a basic ATM cell format interfacing with the WCDMA system, as illustrated inFIG. 4.

As illustrated inFIG. 5, the AAL2 sending/receiving unit321changes the header of the received data in the ATM cell format into a header consisting of a VPI (virtual path identifier) of at least 1 byte and a VCI (virtual channel identifier) of at least 1 byte and sends it to the AAL2 processing unit321. Here, the UDF field contains transmission information such as port number, and the VPI and VCI contain information on virtual path and channel through which data of the ATM cell format are to be transmitted.

The AAL2 processing unit321separates CPS packets from the payload field of the transmitted ATM cell. At this time, the operation of separating CPS packets from the payload field of the ATM cell differs according to the manner in which the CPS packets are loaded on the ATM cell. Hereinafter, the operation of separating CPA packets will be described in more detail with reference to the accompanying drawings.

FIG. 6is an ATM cell data format in which the format of CPS packets separated from the payload filed of an ATM cell is illustrated.FIG. 7is a view illustrating a Start Field format of the ATM cell ofFIG. 6in detail.FIG. 8is a view illustrating a CPA packet format of the ATM cell ofFIG. 6.

As illustrated inFIG. 6, one ATM cell consists of an AH (ATM header) of 5 bytes, a SF (Start Field) of 1 byte and CPS packets. The one ATM cell may contain one or more CPS packets. As illustrated inFIG. 7, the Start Field of the ATM cell contains an Offset Field and a SN (Sequence Number). Each of the CPS packets as illustrated inFIG. 8consists of a CPS-packet header (CPS-PH) and a CPS-packet payload (CPS-PP).

Referring toFIGS. 5 to 8, the offset field of the start field indicates the position where a new CPOS packet is located in the payload of 47 bytes from which the offset field is subtracted. For example, if the offset value is 0, a new CPS packet indicates the next byte of the start field. If the offset value is 47, this means that the CPS packets are completed in the current cell and thus there is not new CPS packet or the current CPS packets are included until the next cell. The position indicated by the arrow of each cell as illustrated inFIG. 6means the position indicated by the offset value.

Therefore, the AAL2 processing unit321separates CPS packets using the offset value of the start field. At this point the CPS packets separated from the ATM cell contains a CPS packet header as illustrated inFIG. 8, but the CPS packet header is separated before the CPS packets are sent to the UP protocol processing unit322. If the data initially transmitted from the first WCDMA network is image data, there may occur the case where two or more CPS packets are combined and sent to the UP protocol processing unit322. For this case, a buffer is allocated to a corresponding subscriber and previous data is stored until a complete image data packet is assembled.

To summarize the operation of the AAL2 processing unit321, CPS packets are separated from the ATM payload, CPS packet payload data in the separated CPS packets are processed in a data format as inFIG. 9, and sent to the UP protocol processing unit322. Here, a connection ID as illustrated inFIG. 9may be a table allocated for managing subscriber information for processing data in each processing unit, which integrally manages subscriber information such as a CID (channel identifier), VPI, VCI, etc. required in each processing unit.

The data format illustrated inFIG. 9is added with a UP protocol-related header in the UP protocol processing unit322, and sent to the RTP processing unit323in a data format as illustrated inFIG. 12. At this time, the CPS packet payload of voice in the data inputted from the AAL2 processing unit322contains a UP header, and thus any particular operation of generating a UP header is not required. However, since the CPS packet payload of image does not contain a UP header, UP header information is acquired from a connection ID.

FIG. 10andFIG. 11are views showing a UP header type generated based on the UP header information acquired from the connection ID. The thus-generated UP header is included in the data format as illustrated inFIG. 12, and the data format is sent to the RTP processing unit323.

The RTP processing unit323receives an input of the data format, acquires RTP header information from the connection ID of the data format, generates a RTP header, and thereafter delivers the data format as illustrated inFIG. 13to the IP processing unit324. The data format processed through the RTP processing unit323from the AAL2 sending/receiving unit310becomes a data format suitable for the IP network.

The IP processing unit324adds a UDP header and an IP header to the data delivered from the RTP processing unit323and sends it to the IP sending/receiving unit330. Next, the IP sending/receiving unit330may generate an Ethernet header in the data delivered from the IP processing unit323, and deliver the data of the type as shown inFIG. 14to a second WCDMA network via the IP network.

At this point, operation of processing and sending data from the IP network to the second WCDMA network is performed in a reverse order of the aforementioned operation of processing and sending data from the first WCDMA network to the IP network. Therefore, each processing unit of the interworking apparatus300processes the above-described data processing procedure in reverse, and delivers the processed data to the second WCDMA network from the IP network. That is, the IP sending/receiving unit330removes the Ethernet header from the data sent via the IP network and sends it to the IP processing unit324. The IP processing unit324removes the UDP header and the IP header from the data delivered from the IP sending/receiving unit330and sends it to the RTP processing unit323.

The RTP processing unit323removes the RTP header from the data delivered from the IP processing unit324and sends it to the UP protocol processing unit322. Then, the UP protocol processing unit322removes the UP protocol-related header from the data of the CPS packet payload delivered from the RTP processing unit323and sends it to the AAL2 processing unit321.

Next, the AAL2 processing unit321generates a Start Field containing an offset value, assembles CPS packets containing data of the CPS packet payload in an ATM payload, and sends an a TM cell generated by assembling to the AAL2 sending/receiving unit310.

Next, the AAL2 sending/receiving unit310removes the UDF added to the delivered ATM cell, and sends the ATM cell from which the UDF is removed to the second WCDMA network. By this operation of the interworking apparatus, data such as voice, video or image can be transmitted to the first WCDMA network to the second WCDMA network via the IP network.

In another embodiment of the present invention where the interworking apparatus300operates between a WCDMA network and an IP network, UP protocol processing unit322does not need to generate a UP protocol header and add it to data. By such an operation, the connection ID in the data delivered to the UP protocol processing unit322is retrieved, whereby the necessity of generation of a UP protocol header can be found.

The interworking apparatus thus operated according to the present invention will be described with reference to the sequence chart as shown inFIG. 15. To send and receive data such as voice or image by interworking from a WCDMA network to an IP network, data added with a UDF in an ATM cell of the WCDMA network is sent to a WCDMA system (S10). Also, data of an ATM cell format including a header changed so as to be comprised of a VPI and VCI is delivered (S20).

The data processed by separating CPS packets from the ATM payload filed of the ATM cell of the step S20is delivered (S30). It is then judged whether the processed data is data delivered to the IP network or data delivered to another WCDMA network via the IP network (S40). At this time, the judgment (S40) is based on connection ID information of the ATM cell. If the data is data delivered to another WCDMA network via the IP network, an UP protocol header is added to the data delivered in the step (S30) is and sent, and if the data is data delivered merely to the IP network, no UP protocol header is added and the data delivered in the step S30is sent (S50).

The data delivered in the step S50is added with a RTP header (S60). When the data is added with a UDP header and an IP header and sent (S70), the data further added (S80) with an Ethernet header is processed and delivered to the IP network (S100).

However, the data of the step S80is data transmitted to another WCDMA network via the IP network (S90). The series of steps S10to S80are then performed in reverse. That is, the data processed by removing the Ethernet header from the data acquired in the step S80is sent (S110), and the UDP header and the IP header are removed from the data (S120).

The data of the step S120is processed and sent after removing the RTP header and the UP protocol header (S130and S140). Next, the data of the step S140is processed into CPS packets, and the CPS packets are assembled into the payload of the ATM cell (S150). The header of the assembled ATM cell is restored to a format corresponding to the header of the initial ATM cell and the restored ATM cell is sent (S160). The initially added UDF is removed from the data of the ATM cell format of the step S160(S170), and the data is transmitted to another WCDMA network.

As described above, the present invention has the effect of accepting VoIP communications in a WCDMA network. Accordingly, a wider variety of content can be provided to subscribers and reliability of service can be improved. Furthermore, a WCDMA network and an IP network can made to interwork between one another, and thus a router as well as a WCDMA system can be added to a network configuration to thereby reduce the cost of building a network configuration infrastructure.