KR20010058355A - Apparatus for transmitting ATM cell by using AAL2 in communication system - Google Patents

Abstract

PURPOSE: An apparatus for transmitting an ATM(Asynchronous Transfer Node) cell using an AAL2(ATM Application Layer 2) of a communication system, is provided to prevent delay phenomenon, and accommodate time slots with various capacity, by enabling a lot of time slot data to be easily multiplexed to VPI/VCI(Virtual Path Identifier/Virtual Channel Identifier). CONSTITUTION: An input part(10) switches the time slots in order to multiplex them. A control part(20) controls the input part(10), a packet process part(30), a CAM(Content Addressable Memory)(40) and an output part(50). The packet process part(30) stores a CPS packet header by a time slot unit. The CAM(40) receives a time slot number and a CID(Channel Identifier) applied from the packet process part(30), and thereby outputs an ATM buffer number. An output part(50) stores the CPS packet data output from the packet process part(30) in an ATM buffer pointed by an ATM buffer number of the CAM(40), completes an ATM cell and then sends it.

Description

Apparatus for transmitting ATM cell by using AAL2 in communication system}

The present invention relates to an apparatus for converting and transmitting time slot data of a communication system to an Asynchronous Transfer Mode (ATM) cell using AAL2 (ATM Application Layer 2). It can convert an ATM cell with a random VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier) from a slot and convert one CPI (Channel Identifier) from another timeslot to one VPI / VCI. The present invention relates to an ATM cell transmitter using AAL2 of a communication system suitable for easily multiplexing multiple channels.

A communication system is a system that performs information processing by combining a terminal with a remote communication line and includes a wired and wireless communication system.

The wireless communication system is a communication system for mobile devices such as people, cars, ships, trains and aircraft, including mobile phones (mobile phones, vehicle phones), port phones, aircraft phones, mobile public phones (trains, cruise ships, Installed on express buses, radio calls, radiotelephones, satellite communications, amateur radio, and fishing service ships. These communications include the Advanced Mobile Phone Service (AMPS) system using analog methods, the CDMA and TDMA (Time Division Multiple Access) systems using digital methods, and the Frequency Division Multiple Access (FDMA) systems. And WLL (Wireless Local Loop) systems.

Thus, a general communication system includes: a switch for transmitting a call processing request of a terminal to another communication network such as a public telephone switching network through a public network or a dedicated network so that a communication service can be made; A base station controller connected to the exchange to control a base station; A base station under the control of the base station controller, transmitting a call transfer request of the exchange to a terminal, and receiving a call processing request of the terminal; The terminal is configured to allow a subscriber to receive communication service in the coverage area of the base station.

Accordingly, in a general communication system, when a subscriber wants to use a communication service while having a subscriber station within a coverage area of a base station, the subscriber's terminal information obtained through the base station is transmitted to the home location register through the exchange. In addition, the communication system operates to perform a voice information service or to connect with another communication network according to a request of a terminal.

1 is a block diagram of an ATM cell transmitter of a conventional communication system.

As shown therein, a time switch unit 1 for switching a time slot of 64 Kbps class; AAL1 Segmentation And Reassembly (SAR) function for receiving Pulse Code Modulation (PCM) data from 256 timeslots output from the time switch unit 1 and segmenting it into ATM cells. AAL1 (2) to perform; A buffer (3) for temporarily storing data of the AAL1 (2) and preventing contention when the control unit (9) accesses the SRAM (4); A static random access memory (SRAM) 4 connected to the buffer 3 for storing PCM and control data; An input buffer unit 5 for temporarily storing data to transmit data when the ATM cell is completed in the AAL1 (2); A CAM / buffer control section 6 for generating a signal for accessing the input buffer section 5, the output buffer section 8 and the CAM (Content Addressable Memory); A CAM (7) which is controlled by the CAM / buffer control unit 6 and converts the time slot number included in the header of the ATM cell into the VPI / VCI information in the AAL1 (2); An output buffer unit 8 for storing VPI / VCI-converted ATM cells under the control of the CAM / buffer control unit 6; The control unit 9 controls to convert the timeslot into VPI / VCI in the CAM 7.

The operation of the conventional apparatus configured as described above is as follows.

First, the conventional apparatus is a structure used when converting from 256 64Kbps time slots to an ATM cell using the AAL1 protocol.

Thus, the time slot of 64 Kbps class is switched from the time switch 1.

Then, it is stored in the SRAM (4) through the SAR controller of the AAL1 (2), divided into ATM cells using the PCM data stored in the SRAM (4), and a time slot number is attached to the ATM cell header to the input buffer section (5). Send.

53 bytes of ATM cells are sequentially stored in the input buffer unit 5, and the CAM / buffer control unit 6 reads the time slot information of the ATM cell header of the input buffer unit 5 to input the CAM 7. And receive VPI / VCI information as output.

The input / output condition of the CAM 7 is inserted in the call connection by the control unit 9 and deleted when the call is released.

The VPI / VCI information output from the CAM 7 replaces the timeslot number, becomes an ATM cell header, is stored in the output buffer unit 8, and is transmitted to the ATM network through the transmitter.

However, in the prior art, in case of AAL1, one VPI / VCI is allocated to one timeslot number, and is mainly used for delay sensitive CBR (Constant Bit Rate) service. There was a disadvantage that can not.

Accordingly, the present invention has been proposed to solve the above-mentioned conventional problems, and an object of the present invention is to convert an ATM cell having a random VPI / VCI from a plurality of input timeslots, and to one VPI / VCI. An ATM cell transmitter using AAL2 of a communication system that can easily multiplex multiple channels having different CIDs from different timeslots.

In order to achieve the above object, an ATM cell transmitter using AAL2 of a communication system according to an embodiment of the present invention,

An input unit for switching and multiplexing a plurality of timeslots; A control unit controlling operations of the input unit, the packet processing unit, the CAM, and the output unit; A packet processing unit for storing a CPS packet header in units of time slots output from the input unit; A CAM for receiving the timeslot number and the CID output from the packet processor and outputting an ATM buffer number; The CPS packet data output from the packet processing unit is stored in an ATM buffer indicated by the ATM buffer number of the CAM, and comprises an output unit for completing and transmitting an ATM cell.

1 is a block diagram of an ATM cell transmitter of a conventional communication system,

2 is a block diagram of an ATM cell transmitter using AAL2 of a communication system according to an embodiment of the present invention;

3 is a structural diagram of a general AAL3 CPS packet,

4 is a cell structure diagram of a general ATM layer.

Explanation of symbols on the main parts of the drawings

10 input unit 11 time switch unit

12: buffer 13: multiplexing unit

20: control unit 30: packet processing unit

31: packet header generation unit 32: HEC generation unit

33: CPS packet buffer unit 40: CAM

50: output unit 51: ATM buffer

52: ATM header generation unit 53: transmission buffer unit

Hereinafter, an embodiment according to the technical concept of the ATM cell transmitter using AAL2 of the present invention as described above is as follows.

First, in the prior art, in case of AAL1, one VPI / VCI is allocated to one timeslot number, and is mainly used for delay-sensitive CBR service. In the case of AAL2 used in the present invention, a plurality of VPI / VCIs are used in one VPI / VCI. The multiplexing of timeslots allows for efficient use of bandwidth and is useful for variable bit rate (VBR) services.

2 is a block diagram of an ATM cell transmitter using AAL2 of a communication system according to an embodiment of the present invention.

As shown therein, the input unit 10 switches and multiplexes a plurality of timeslots; A controller 20 for controlling operations of the input unit 10, the packet processing unit 30, the CAM 40, and the output unit 50; A packet processing unit 30 for storing the CPS packet header in units of time slots output from the input unit 10; A CAM 40 for receiving the timeslot number and the CID output from the packet processor 30 and outputting the ATM buffer number; And an output unit 50 for storing CPS packet data output from the packet processing unit 30 in an ATM buffer indicated by the ATM buffer number of the CAM 40, and completing and transmitting the ATM cell.

The input unit 10 includes a time switch unit 11 for switching an input time slot; A plurality of buffers 12 respectively storing data from a plurality of timeslots output from the time switch section 11; The multiplexer 13 is configured to multiplex the timeslots output from the plurality of buffers 12 to select and output valid data among the data of the plurality of buffers 12.

The packet processing unit 30 includes: a packet header generation unit 31 for generating a packet header for storing the CPS packet header in units of time slots input from the input unit 10; A HEC generation unit 32 generating and inserting an HEC in units of time slots input from the input unit 10; The CPS packet buffer unit 33 stores data of the input unit 10 and data of the packet header generator 31.

The output unit 50 includes: a plurality of ATM buffers 51 for storing CPS packet data output from the packet processing unit 30 in an ATM buffer indicated by the ATM buffer number of the CAM 40; ATM header generation unit 52 for storing 53 octets of ATM cells by storing information for generating 5 octets of the required ATM cell payload from 48 octets stored in the plurality of ATM buffers 51. )Wow; The ATM header generation unit 52 includes a transmission buffer unit 53 for storing and transmitting the completed ATM cell.

In the above, the control unit 20 makes the corresponding buffers of the plurality of buffer units 12 in the input unit 10 valid when the call is connected, and then writes the same time slot number as the buffer number in the first octet, and subsequently the CPS packet. After writing the header, if there is a valid CPS packet, the time slot number, which is the first octet, and the CID of the second octet are read to be the input of the CAM 40, and the ATM buffer number is read as the output, and the timeslot / CID is read. By writing an ATM buffer number as an input condition, by assigning different timeslots / CIDs to the same ATM buffer number, CPS packets having multiple CIDs in one ATM buffer are controlled to be multiplexed.

The operation of the ATM cell transmitter using AAL2 of the communication system according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, ATM is a transport / switching technology that is the core of B-ISDN (Broadband Integrated Services Digital Network), and treats all information as ATM cells. The ATM terminal performs a telephone service using an ATM, and performs functions such as selecting a communication line, setting up an error, and detecting an error. The ATM cell has a length of 53 bytes, with a header of 5 bytes and an information field of 48 bytes. The fixed-length data string is a unit of multiple exchanges.

Here, AAL includes AAL1, AAL2, AAL3 / 4, and AAL5. AAL1 delivers SDUs (Service Data Units) of equal bit rate at the same bit rate, transfers time information between information sources and destinations, and displays error recovery and unrecovered errors. AAL2 also delivers SDUs at variable bit rates, transfers time information between information sources and destinations, and indicates error recovery and unrecovered errors. In addition, AAL3 and 4 provide non-real-time and variable bit rate services to ATM-SAP from ATM Application Layer-Service Access Point (AAL-SAP), multiplexing services at the AAL layer, It delivers in a connectionless manner. In addition, AAL5 simplifies the function and processing of AAL3 / 4, making it suitable for high-speed data transfer.

Accordingly, the present invention describes its operation as a structure used when converting from N 64Kbps-class timeslots to ATM cells having a plurality of VPI / VCIs using the AAL2 protocol.

First, FIG. 3 is a structure diagram of a general AAL3 CPS packet, and FIG. 4 is a cell structure diagram of a typical ATM layer.

Thus, time slot data of 64 Kbps class from the time switch unit 11 are stored in the buffers 0 to N of the buffer unit 12 by number. The first octet of the buffer unit 12 indicates a valid or invalid state.

The control unit 20 makes Invalid at initialization.

When the call is connected, the control unit 20 makes the corresponding state valid.

The multiplexer 13 scans buffers 0 to N periodically. When the first octet of the buffer is valid, as shown in the AAL2 CPS packet structure of FIG. 3, the CID, LI (Length Indicator), and UUI (User-to-User Indicator) of the packet header generation unit 31 indicated by the buffer number. ) To generate HEC.

When the call is connected, the controller 20 reads the CID, LI, and UUI of the corresponding time slot to the packet header generator 31.

The CPS packet buffer unit 33 writes the same time slot number as the buffer number in the first octet, sequentially writes the CPS packet header, and writes CPS = INFO. In this case, the CPS-INFO has a length allocated by the controller 20. The CPS packet buffer unit 33 is stored in the order output from the multiplexer 13.

When there is a valid CPS packet, the time slot number, which is the first octet of the CPS packet buffer unit 33, and the CID of the second octet are read out to be input to the CAM 40, and the ATM buffer number is read out as an output.

The controller 20 controls the CAM 40 to write the ATM buffer number as the output condition with the timeslot / CID as the input condition.

Assigning different timeslots / CIDs to the same ATM buffer number can result in multiplexing CPS packets with multiple CIDs in one ATM buffer.

The ATM header generation unit 52 can store as many ATM cell headers as there are ATM buffers 51, and the ATM buffer number and the ATM cell header index are matched one-to-one. Therefore, the controller 20 writes data matching the ATM buffer number output from the CAM to the ATM header generator 52 to write VPI / VCI.

When 48 octets of data are received in the plurality of ATM buffer units 51, the ATM header generation unit 52 attaches an ATM cell header to store 53 octets of ATM cell data in the transmission buffer unit 53. Transmit to ATM network.

As described above, the present invention can convert an ATM cell having a random VPI / VCI from a plurality of input timeslots, and easily multiplex multiple channels having different CIDs from different timeslots in one VPI / VCI.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, an ATM cell transmitter using AAL2 of the communication system according to the present invention can easily perform multiplexing of multiple timeslot data in one VPI / VCI, thereby preventing delay. In addition, according to the system specification, it is possible to accommodate various timeslots of various capacities.

Claims (5)

An input unit for switching and multiplexing a plurality of timeslots; A control unit controlling operations of the input unit, the packet processing unit, the CAM, and the output unit; A packet processing unit for storing a CPS packet header in units of time slots output from the input unit; A CAM for receiving the timeslot number and the CID output from the packet processor and outputting an ATM buffer number; And an output unit configured to store CPS packet data output from the packet processing unit in an ATM buffer indicated by the ATM buffer number of the CAM and complete and transmit the ATM cell. The method of claim 1, wherein the input unit, A time switch unit for switching the input timeslot; A plurality of buffers respectively storing data from a plurality of timeslots output from the time switch unit; And a multiplexer configured to multiplex the timeslots output from the plurality of buffers to select and output valid data among the data of the plurality of buffers. The method of claim 1, wherein the packet processing unit, A packet header generation unit generating a packet header for storing a CPS packet header in units of time slots inputted from the input unit; A HEC generation unit generating and inserting an HEC in units of time slots input from the input unit; And a CPS packet buffer unit for storing the data of the input unit and the data of the packet header generation unit. The method of claim 1, wherein the output unit, A plurality of ATM buffers for storing the CPS packet data output from the packet processing unit in an ATM buffer indicated by the ATM buffer number of the CAM; An ATM header generation unit for storing information for generating a 5 octet header of an ATM cell payload required from 48 octets stored in the plurality of ATM buffers and completing a 53 octet ATM cell; An ATM cell transmitter using AAL2 of a communication system, characterized by comprising a transmission buffer unit for storing and transmitting the ATM cell completed by the ATM header generation unit. The method of claim 1, wherein the control unit, When a call is connected, the corresponding buffer of the plurality of buffers in the input unit is made valid, and then the first octet is written if there is a valid CPS packet after writing the same time slot number as the buffer number in the first octet, and successively writing the CPS packet header. Read the in-time slot number and the CID of the second octet to make the input of the CAM and to read the ATM buffer number as the output, and write the ATM buffer number as the output condition with the timeslot / CID as the input condition, the same ATM buffer number An ATM cell transmitter using AAL2 of a communication system, characterized in that CPS packets having multiple CIDs are multiplexed in one ATM buffer by allocating different timeslots / CIDs to one another.