KR100354163B1 - A AAL2 protocol realization Apparatus and its method in Mobile communication system, a multiple virtual channel is supported by the AAL2 protocol - Google Patents

Abstract

The present invention relates to an AAL2 protocol implementation apparatus and method for supporting multiple virtual channels in a mobile communication system suitable for transmitting and receiving packet data through a plurality of virtual channels set according to a destination using an AAL2 protocol at a base station and a switching center. will be. The AAL2 protocol implementation method for supporting multiple virtual channels in the mobile communication system according to the present invention includes generating multiplexed packet data input from the mobile terminal as protocol data, and identifying the virtual channel set for each destination in the protocol data. Allocating information, and routing and transmitting the protocol data to the corresponding virtual channel according to the assigned identification information, thereby increasing the capacity that the communication system can accommodate and increasing the transmission speed, thereby ensuring stable communication service. There is an effect that can provide.

Description

A AAL2 protocol realization Apparatus and its method in Mobile communication system, a multiple virtual channel is supported by the AAL2 protocol

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to support multiple virtual channels in a mobile communication system suitable for transmitting / receiving packet data through a plurality of virtual channels set according to a destination using an AAL2 protocol at a base station or a switching center. An apparatus and method for implementing the AAL2 protocol are described.

In general, a base station or a switching center of a mobile communication system transmits packet data to a destination using a transmission method of an asynchronous transfer mode (hereinafter, referred to as ATM). ATM transmission method divides user information into a certain packet size, adds destination information to the header of the packet, generates a cell of fixed size (53 bytes), and delivers the generated cell to the destination. . In this ATM transmission scheme, a protocol for transmitting packet data is composed of a physical layer, an ATM layer, an AAL layer, and a higher layer. Here, the AAL layer is a layer for reassembling user application data (that is, packet data) from the upper layer into 48 bytes, and the AAL1 format to the AAL5 format are defined (see I Series Recommendation of ITU-T). At this time, the AAL2 protocol is to provide a variable rate and real-time service for packet data.

The following is the purpose of recommendation of the AAL2 protocol.

When the ATM transmission method transmits user information having a low bit rate characteristic, the actual valid data fills only a part of the ATM cell payload, and the remaining unfilled part is padded with '0' and transmitted. Accordingly, when the ATM transmission scheme is applied to a mobile communication system, data having a low bit rate, such as voice data transmitted from a plurality of mobile terminals serviced by the same base station, is packed and transmitted in different cells. This wastes the payload portion of the cell and also introduces a delay in which packet data transmitted from another mobile terminal cannot be transmitted while packet data of short length is packed into one cell and transmitted. To solve this problem, the AAL2 protocol is recommended.

This AAL2 protocol is described in detail below.

1 is a view for explaining the structure of the AAL2 protocol according to the prior art.

Referring to FIG. 1, the AAL2 protocol is divided into a service specific convergence sublayer (hereinafter abbreviated as SSCS) and a common sublayer (hereinafter abbreviated as CPS).

Packet data transmitted from the mobile terminal enters the AAL layer through a service access point (SAP) of a higher layer (not shown) in the form of a service data unit (SDU). In SSCS, a header and a trailer are added to an SDU to generate SSCS-PDU (Protocol Data U12nit).

Then, the CPS generates a CPS-packet by adding a CPS-head to the CPS-SDU, and generates a 48-byte CPS-PDU by adding a start field to the CPS-PDU payload. At this time, the CPS-packet becomes a payload of the CPS-PDU. Since the CPS-PDU is 48 bytes, the CPS-packets of a plurality of users are multiplexed into the payload of the CPS-PDU.

The CPS-PDU is transmitted to the ATM layer. The ATM layer adds 5 bytes of destination information to the CPS-PDU to generate a 53-byte cell.

As such, the packet data received from the mobile terminal is divided into 48 bytes through the AAL2 protocol and used as payload of the ATM cell.

FIG. 2 is a diagram showing a data structure of a CPS-packet generated in the AAL2 protocol shown in FIG. 1, and FIG. 3 is a diagram showing a data structure of a CPS-PDU generated in the AAL2 protocol shown in FIG.

2 or 3, a CPS packet is composed of a CPS header and a CPS payload. In this case, the CPS-header is an 8-bit CID (Channel Identifier) field for distinguishing a plurality of users in one virtual channel (hereinafter, abbreviated as VC), and 6 representing a payload size of the CPS-packet. Length indicator (LI) field of bits, user-to-user indication (UUI) field to distinguish SSCS data, CPS user and network manager, and 5-bit HEC (error error) for error correction of CPS-packet header Control) field. Here, since the CID field is 8 bits, one virtual channel can accommodate 256 users.

In addition, the CPS-PDU is a start field consisting of an OSF (Offset field), a serial number (Sequence Number), and a parity bit (P) indicating the size from the payload start point of the CPS-PDU to the start point of the next CPS-packet It consists of a payload and a padding field.

Since the AAL2 protocol can multiplex short packet data transmitted from multiple users on an ATM network into one cell, it can reduce the time required for packing short user data into a new cell and also efficiently bandwidth the ATM network. It can be used as an advantage.

However, the conventional AAL2 protocol supports transmission through a single virtual channel as a standard when transmitting packet data to a destination, but is supported by a multiple virtual channel, that is, through a plurality of virtual channels. The transmission of packet data (or cells) has not yet been recommended as a standard.

Accordingly, a plurality of mobile terminals, base stations, or switching stations in the AAL2 protocol are not able to transmit packet data through a plurality of virtual channels, thereby causing a limitation in user capacity and transmission rate.

For this reason, there has been a constant demand for standardization of the AAL2 protocol supporting multiple virtual channels in mobile communication systems.

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the prior art, and the AAL2 protocol used in a base station or an exchange station supports a plurality of virtual channels, and thus can transmit a cell through a virtual channel according to a destination. It is an object of the present invention to provide an AAL2 protocol implementation apparatus and method for supporting multiple virtual channels in a mobile communication system.

According to an aspect of the present invention for achieving the above object, the AAL2 protocol implementation apparatus for supporting multiple virtual channels in the mobile communication system is a first to store the CID information for user identification of the packet data input from the mobile terminal A second memory configured to store a memory, identification information for distinguishing a virtual channel according to a destination of the packet data, and multiplexing or demultiplexing the packet data using the CID information and the identification information to perform virtualization according to the identification information. A transmitter for transmitting packet data through a channel, and a buffer unit for storing the packet data transmitted from the transmitter in the virtual channel.

Preferably, the transmitter is an input controller for controlling the packet data input from the mobile terminal, the CID information and the identification information is assigned to the packet data to convert the protocol data or the protocol data input from the buffer unit And a transmission / reception function unit for demultiplexing and converting the packet data into packet data according to the CID information and the identification information, and an output controller for transmitting the protocol data converted in the transmission / reception function unit to the plurality of buffer units.

According to another aspect of the present invention for achieving the above object, the AAL2 protocol implementation method for supporting multiple virtual channels in a mobile communication system comprises the steps of: generating multiplexed packet data input from the mobile terminal as protocol data; Allocating identification information of a virtual channel set for each destination to the protocol data, and routing and transmitting the protocol data to the corresponding virtual channel according to the assigned identification information.

Preferably, the generating of the protocol data includes channel identifier information (CID) information for distinguishing a user from the packet data, length indicator (LI) information indicating a payload size, user-to-user indication (UUI) information, and the like. Allocating a header consisting of HEC (Header Error Control) information for error correction, OSF (Offset Field) indicating the start point and end point of the payload of the identification information of the virtual channel and the protocol data to the packet data allocated to the header portion ) And a start field consisting of information, a serial number of protocol data, and a parity bit for error correction.

In addition, a predetermined byte having identification information for identifying the virtual channel is additionally allocated to the protocol data, and is transmitted through a buffer provided for each virtual channel.

1 is a view for explaining the structure of the AAL2 protocol according to the prior art.

FIG. 2 shows the data structure of a CPS-packet generated in the AAL2 protocol shown in FIG.

3 is a diagram showing a data structure of a CPS-PDU generated in the AAL2 protocol shown in FIG.

4 is a block diagram of an AAL2 protocol implementation apparatus supporting multiple virtual channels in a mobile communication system according to the present invention.

FIG. 5 is a diagram illustrating a structure of a CPS-PDU output from the AAL2 transmitter shown in FIG. 4.

* Description of the symbols for the main parts of the drawings *

410, 460: CT (CID Table) 420, 470: MT (Multi VC Table)

430: AAL2 transmitter 440: transmission buffer unit

450: receiving buffer unit 480: AAL2 receiver

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention proposes an apparatus and method for implementing AAL protocol capable of supporting a plurality of virtual channels in a mobile communication system. Accordingly, a base station (more specifically, a base station controller) or an exchange that uses the AAL2 protocol according to the present invention can transmit packet data (or cells) to a corresponding destination using a plurality of virtual channels.

4 is a block diagram of an AAL2 protocol implementation apparatus supporting multiple virtual channels in a mobile communication system according to the present invention.

Referring to FIG. 4, packet data received from a plurality of mobile terminals (not shown) is transformed into CPS-packets and multiplexed to generate 48-byte CPS-PDUs, and the generated CPS-PDUs are virtualized according to destinations. AAL2 transmitter 430 for routing and transmitting to the channel and the 48-byte CPS-PDU received from the switching center (not shown) are demultiplexed to generate a CPS packet, and the generated CPS packet is a mobile terminal corresponding to the destination. AAL2 receiver 480 for transmitting to the network, CT (CID Table) (410) (460) for storing the CID information allocated to the CPS-packet during call setup to support a plurality of virtual channels, and the corresponding CPS-PDU Multi VC table (MT) 420 and 470 for storing V_Tag information for identifying a virtual channel set as a destination, and a transmission buffer unit for storing CPS-PDUs transmitted from the AAL2 transmitter 430 or the exchange for each virtual channel. 440 and the reception buffer unit 450.

Here, the AAL2 transmitter 430 or the AAL2 receiver 480 transmits an input controller (431) 482 for receiving a CPS-packet transmitted from a mobile terminal or a CPS-PDU transmitted from an exchange. Output FIFO Controller 432 (481) for controlling the buffer unit 440 to transmit the CPS-PDU for each virtual channel or to transmit the CPS-packet output from the AAL2 receiver 480 to the mobile terminal. It is provided.

The CT 410, 460, and MT 420, 470 store CID information and V_tag information using a DPRAM.

The operation of the AAL2 protocol implementing apparatus supporting multiple virtual channels in the mobile communication system configured as described above will be described below.

First, a case of transmitting packet data in a mobile terminal will be described.

First, the packet data transmitted from the mobile terminal to the base station (not shown) is generated as a CPS packet in the CPS of the AAL2 protocol and input to the AAL2 transmitter 430. At this time, the CPS-packet data is input to the AAL2 transmitter 430 through the input controller 431.

Then, the AAL2 transmitter 430 allocates 8-bit CID (Channel Identifier) information for identifying the user of each packet data to the CPS-packet data using the AAL2 Negotiation Protocol (ANP). The CID information is stored in the CT 410.

Subsequently, the AAL2 transmitter 430 is a user-to-user indication (UUI) for distinguishing 6-bit length indicator (LI) information representing the payload size of the CPS-packet data, SSCS data, CPS user, and network manager. Information, and 5-bit HEC (Header Error Control) information for error correction of the CPS-packet header is allocated in this order. This process is processed by the AAL2 transmission function unit 433 provided in the AAL2 transmitter 430.

Such CPS-packet data, that is, a CPS-packet to which CID, LI, UUI, and HEC information are allocated, becomes a CPS-PDU (Protocol Data Unit).

Then, the AAL2 transmitter 430 assigns the generated CPS-PDU to V_tag, which is information for identifying the virtual channel set as the corresponding destination from the MT 420. Preferably V_tag is 1 byte.

The V_tag assigned by the MT 420 is a Virtual Path Identifier (VPI) and a Virtual Channel Identifier (Virtual Channel Identifier) for routing to a corresponding destination in a 53-byte cell generated using the CPS-PDU as a payload at the ATM layer. Channel Identifier).

Subsequently, the AAL2 transmitter 430 allocates an offset field (OSF), a sequence number, and a parity bit (P) to the CPS-PDU, indicating the size of the CPS-PDU payload starting point to the next CPS-packet starting point. Create a 48-byte CPS-PDU.

The 48-byte CPS-PDU is routed through the output controller 432 to a virtual channel according to V_tag and transmitted. At this time, each virtual channel set as a corresponding destination is provided with transmission buffers 441a to 441n so that the CPS-PDU is first stored in the transmission buffer unit 440 provided in the corresponding virtual channel.

That is, since the transmission buffers 441a to 441n are allocated for each virtual channel by the number of virtual channels, the CPS-PDUs are assigned to the transmission buffers 441a to 441n provided for each virtual channel according to the V_tag allocated from the MT 420. It can be printed.

The 48-byte CPS-PDU transmitted to the transmission buffer unit 440 is regenerated into a cell added with a head including a virtual path identifier (VPI) and a virtual channel identifier (VCI) in the ATM layer, and the regenerated cell is set as a corresponding destination. It is transmitted through the virtual channel.

As such, the base station to which the AAL2 protocol of the present invention is applied may transmit a cell to a corresponding switching center (or destination) through a plurality of virtual channels set as destinations.

Preferably, 256 virtual channels can be set because 8 C bits assigned to the CPS-PDU can distinguish 256 users.

On the other hand, the operation of the AAL protocol implementation apparatus that supports multiple virtual channels in the case where a cell is transmitted through a plurality of virtual channels from the switching center to the mobile terminal will be described below.

Cells transmitted through the plurality of virtual channels from the switching center to the base station are decomposed into 48-byte CPS-PDUs including V_tag through the ATM layer, and are then stored in the plurality of receive buffers 451a to 451n provided for each virtual channel.

Subsequently, the 48-byte CPS-PDU is input to the AAL2 receiver 480 through an input controller 482 that controls the reception buffers 451a to 451n, and the AAL2 reception function unit 483 is stored in the MT_470. A plurality of CPS-PDUs are transmitted according to their destinations, and CPS-PDUs are distinguished by CPS-PDUs transmitted in one virtual channel by using a CID stored in the CT 460.

In this case, the AAL2 receiver 480 performs demultiplexing to generate a CPS-packet in order to transmit the CPS-PDU for each destination.

Subsequently, the packet data generated by the AAL2 receiver 480 is transmitted to the mobile terminal corresponding to the destination.

FIG. 5 is a diagram illustrating a structure of a CPS-PDU output from the AAL2 transmitter shown in FIG. 4.

Referring to FIG. 5, in the CPS-PDU generated by the AAL2 transmitter, one byte of V_tag is added to a 48-byte payload.

In this case, the V-tag is information for identifying a plurality of virtual channels, and the payload is a CPS-PDU generated through the AAL2 transmitter.

As described above, the present invention can transmit a cell through a plurality of virtual channels by using an ALL2 protocol implementation device that supports multiple virtual channels at a base station and a switching center of a mobile communication system. In addition, the transmission speed is also increased, thereby providing a stable communication service.

In addition, the present invention can be applied to an IMT-2000 system and a digital cellular network that are currently under development.

Claims (7)

A first memory for storing CID information for identifying a user of packet data input from the mobile terminal; A second memory for storing identification information for classifying a virtual channel according to a destination of the packet data; A transmitter for multiplexing or demultiplexing the packet data using the CID information and the identification information and transmitting the packet data through a virtual channel according to the identification information; And a buffer unit configured to store the packet data transmitted from the transmitter in the virtual channel. The method of claim 1, wherein the transmitter, An input controller for controlling packet data input from the mobile terminal; A transmission / reception function unit which allocates the CID information and identification information to the packet data and converts the protocol data into protocol data or demultiplexes protocol data input from the buffer unit according to the CID information and identification information into packet data; , And an output controller for transmitting the protocol data converted by the transmission / reception function unit to the plurality of buffer units. Multiplexing packet data input from the mobile terminal to generate protocol data; Allocating identification information of a virtual channel set for each destination to the protocol data; AAL2 protocol implementation method for supporting multiple virtual channels in a mobile communication system, characterized in that it comprises the step of routing the protocol data to the corresponding virtual channel according to the assigned identification information. The method of claim 3, wherein the generating of the protocol data, Channel Identifier (CID) information for distinguishing a user from the packet data, length indicator (LI) information indicating a payload size, user-to-user indication (UUI) information, and HEC (Header Error Control) for error correction Allocating a head consisting of information, Allocating the header field to the packet data allocated to the start field consisting of identification information of the virtual channel, OSF (Offset Field) information indicating the payload start point and end point of the protocol data, serial number of the protocol data, and parity bits for error correction AAL2 protocol implementation method for supporting multiple virtual channels in a mobile communication system, characterized in that consisting of. 4. The method of claim 3, wherein the protocol data is further allocated with a predetermined byte having identification information for identifying the virtual channel. The method of claim 3, wherein in the step of transmitting the protocol data, The protocol data is AAL2 protocol implementation method for supporting multiple virtual channels in a mobile communication system, characterized in that transmitted through a buffer provided for each virtual channel. Receiving protocol data over a plurality of virtual channels from at least one switching center, Demultiplexing the received protocol data to generate packet data, and classifying the generated packet data by user or by virtual channel; And transmitting the separated packet data to a mobile terminal according to a destination.