KR0185861B1 - Apparatus and method for generating a pointer of sdt in aal type 1 - Google Patents

Abstract

The present invention relates to a pointer generating apparatus for transmitting structured data in AAL type 1 and a method of generating the same, and more particularly, to a pointer generating apparatus for performing a counting on user data from a user clock from an upper layer, A counter (12) for counting the number of data items; A first register 13 for outputting a count bit twice as large as the count value from the counter 12; A second register (14) for outputting a count bit obtained by adding one to the count value from the counter (12); A multiplexer (16) for selectively outputting count bits from the first and second registers (13, 14); A third register 15 for forming and outputting a pointer by a count bit from the multiplexer 16 and a parity bit from the parity generating means 17; The first and second registers 13 and 14 are selectively enabled by the first and second frame signals from the upper layer and the selection signal is output to the far multiplexer 16, 15). ≪ / RTI >

Description

Pointer generating device for transferring structured data in AAL type 1 and its generating method

More particularly, the present invention relates to a pointer generator for transmitting structured data in AAL type 1, and more particularly to a pointer generator for inputting two 8-bit data, for example, 16-bit data units from an upper layer, -PDU), and then transmitted to the ATM layer by 16 bits each. In order to provide information on the user data structure, an external signal different from the data from the data bus, for example, two frame signals, The present invention relates to a pointer generating apparatus for transmitting structured data in AAL type 1 in which pointers for transmission are generated, and a method for generating the pointers.

In general, an ATM adaptation layer performs a function of adapting a service provided by an ATM layer to a requirement of an upper layer user. Therefore, the ATM adaptation layer must provide the interface between the ATM environment and the non-ATM environment in addition to supporting the user plane, the higher function of the control plane, and the management plane.

In ATM adaptation layer, protocol data unit (PDU) of upper layer is mapped to payload region of ATM cell, and transmission error is handled, and processing of lost cell and inserted cell, flow control Thereby providing a timing control function. The ATM adaptation layer is divided into two sublayers: a segmentation and reassembly (SAR) sublayer and a convergence sublayer (CS).

The Convergence Layer CS performs a function related to a specific service, and the Segmentation and Reassembly (SAR) processes a function related to service termination to process functions related to segmentation and reunion of user information. Therefore, at the transmitting end, the converging sub-layer CS is received from the upper layer as user information, forms a converged sub-layer protocol data unit (CS-PDU) by attaching a header and a trailer to the sub- The segmentation and reassembly (SAR) sublayer cuts it to the size of an ATM cell, attaches a header and a trailer to form a segmentation and reassembly protocol data unit (SAR-PDU), and transmits it through the ATM layer.

At the receiving end, the SAR sub-layer extracts only the payload section among the segmentation and re-association protocol data units (SAR-PDUs) received through the ATM layer to form a converged sub-layer protocol data unit (CS-PDU) And then transmits it to the convergence sublayer CS. In this convergence sublayer CS, only the upper layer user information of the received convergence sublayer protocol data unit (CS-PDU) is extracted and transferred to the upper layer.

At this time, the header and the trailer attached to each sub-layer in the transmission process are related to error handling, buffer management and order preservation, and in the reception process, if the information is analyzed and it is determined that there is no error, Layer.

In ITU-T, user services are classified into four types according to the constant bit rate (CBR), real-time property, and connectivity, and AAL type 1 to 4, respectively. In addition, the ITU-T meeting in June 1992 newly discussed AAL type 5 for supporting high-speed data communication.

In the AAL type 1, a real-time ID bit rate service is provided in a connected mode and a service provided to a user is largely divided into CBR data transmission, timing information transmission, user data structure information transmission, Error, and loss of information.

On the other hand, in the case of the CBR data processing method of the AAL type 1, since data transmission is performed using an 8-bit data bus, the processing speed of the data is lowered, and thus a 16-bit data bus, It is necessary to transfer data using a bus.

Therefore, in the case of transmitting the information of the user data structure to the user data in the AAL type 1, that is, when it is necessary to preserve the boundary of the user data structure, for example, in the case of 8 kHz structured data, CS), the start of the user data block is represented by a pointer, and structured data transfer using such a pointer is required.

In order to solve the above-mentioned problem, the present invention provides a method and apparatus for transmitting and receiving 16-bit data from an upper layer by using 8-bit data, for example 16-bit data units, In order to provide information on the user data structure, a pointer for transferring structured data is generated by using an external signal different from the data from the data bus, for example, two frame signals, The present invention provides a pointer generating apparatus for transmitting structured data in the AAL type 1 and a method of generating the same, which can provide a function of bit error detection and correction in user data when a malfunction occurs.

According to an aspect of the present invention, there is provided a data processing apparatus including a counter for counting user data from a user clock from an upper layer and counting user data for calculating an offset field of a pointer; A first register for outputting a count bit twice as large as a count value from the counter; A second register for outputting a count bit obtained by adding one to the count value from the counter; A multiplexer for selectively outputting count bits from the first and second registers; A third register for forming and outputting a pointer by a count bit from the multiplexer and a parity bit from the parity generating means; The first and second registers are selectively enabled by the first and second frame signals from the upper layer, the selection signal is output to the far multiplexer, and the third register is enabled.

The present invention configured as described above is configured such that data is transmitted from the upper layer to each of two 8-bit data, for example, 16-bit data units, formed into a segmentation and recombination protocol data unit (SAR-PDU) Using a 8-bit data bus by generating a pointer for transferring structured data using an external signal different from the data from the data bus in order to provide information on the user data structure in the processing apparatus, for example, two frame signals It is possible to provide the advantage of being able to process structured data at a faster rate than that.

1 is a conceptual diagram showing a general ATM protocol reference model,

2A shows a data format of an ATM cell,

2B shows a header structure at a user network interface (UNI)

2C is a diagram showing a header structure at a network node interface (NNI)

3A is a diagram showing a data format for each layer in the ATM communication system,

FIG. 3B is a diagram illustrating the SAR format of AAL type 1 shown in FIG. 2A,

Figures 4A-4C illustrate segmentation and reassembly protocol data units (SAR-PDUs) and pointer intervals for structured data delivery;

5 is a diagram illustrating an embodiment of a pointer generator for transferring structured data in AAL type 1 according to the present invention;

6 shows an apparatus for forming a segmentation and recombination protocol data unit (SAR-PDU) using a pointer generator for transferring structured data in the AAL type 1 according to the present invention,

7 is a flowchart illustrating a pointer generation method for transferring structured data in the AAL type 1 according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

10, 11: first and second FIFO 12: 6-bit counter

13, 14, 15: first, second and third registers 16, 22: multiplexer

17: Parity generator 18:

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, an ATM system to which the present invention is applied will be briefly described in order to facilitate understanding of the present invention.

FIG. 1 is a conceptual diagram illustrating an ATM protocol reference model, wherein the topology is composed of a management plane, a control plane, and a user plane, Management and plane management. And, plane management means overall management of the system, and layer management performs management of resource and usage variables and OAM information management.

In addition, the control plane manages call control and connection control information, and the user plane transmits user information. The protocol of the control plane and the user plane is composed of an upper layer, an ATM adaptation layer, an ATM layer, and a physical layer.

As shown in FIGS. 2A to 2C, the ATM cell is divided into a plurality of ATM cells, and the received ATM cells are reassembled into one message and transmitted to the upper user .

FIG. 2A shows a data format of an ATM cell, FIG. 2B shows a header structure at a user network interface (UNI), and FIG. 2C shows a header structure at a network node interface (NNI).

Here, the ATM cell is divided into a 5-byte (or octet) header section and a 48-byte user information section, and a 5-byte header is divided into a user network interface (UNI) The header structure of the UNI is divided into 4 bits of generic flow control (GFC) and 4 bits of virtual path identification (VPI) identifier.

The second byte is composed of a 4-bit virtual path identification number VPI and a 4-bit virtual channel identifier (VCI), and the third byte is an 8-bit virtual channel identification number (VCI) And the fourth byte is composed of a 4-bit virtual channel identification number (VCI), a 3-bit payload type (PT), and a 1-bit cell loss priority (CLP) The byte consists of 8 bits of header error control (HEC).

2C, the general flow control (GFC) in the first byte of the user network interface (NNI) has a virtual path identification number (VPI) It is possible to know the header structure of the user network interface (NNI) except that it is used. The ATM communication method has a hierarchical structure as shown in Table 1, and has standardized standards for each layer.

Layer Sub-layer function Upper layer Upper layer function ATM adaptation layer Convergence (CS) sub-layer Convergence function Cutting and recombination (SAR) Cutting function and recombination function ATM layer Generic flow control and cell header processing Physical layer Transmission Convergence (TC) HEC signal generation and extraction function Physical medium Bit time information function

As shown in Table 1, the ATM communication method is classified into a vertical structure such as a physical layer, an ATM layer, an ATM adaptation layer (AAL), and an upper protocol layer, and the AAL layer is divided into a truncation and recombination sub- segmentation and reassembly sublayer and a convergence sublayer (CS) sublayer. The physical layer is divided into a physical medium (PM) and a transmission convergence (TC) sublayer.

In addition, the service requested by the user in the ATM communication system can be classified as shown in Table 2 according to the characteristics thereof.

Types of Services Time relationship between ends Bit rate Connection mode Examples of services A species Real-time cast Equality Connectivity Odds ratio video signal B species Real-time cast variable Connectivity Variable rate video signal C species Non-real-time property variable Connectivity Connectivity data D species Non-real-time property variable Non-connectivity Non-connectivity data

The AAL protocol corresponding to the service is divided into AAL 1 to AAL 5 as shown in Table 3 below.

AAL form Typical functions AAL 1 Supports class A service with constant bit rate AAL 2 Supports Class B service with real-time property and variable bit rate AAL 3/4 Supports C and D service with variable bit rate AAL 5 Simplifies AAL 3/4 functionality to support high-speed services

In Table 3, the AAL layer is horizontally divided into AAL 1, AAL 2, AAL 3/4, and AAL 5 to efficiently process the corresponding service according to the type of the service.

Here, the AAL 1 layer includes a converging sublayer (CS) for transparently transmitting an A-type service data unit (U-SDU) having a constant bit rate, detecting a transmission error, and performing information identification and clock synchronization functions The ATM cell is divided into variable length data obtained by dividing the variable length data received from the convergence sublayer (CS) and transmitted to the ATM layer. The ATM cell is received and reassembled to recover the CS-PDU. ).

The convergence (CS) sublayer includes a common part convergence sublayer (CPCS) that performs functions common to the connectivity and non-connectivity services, a service specific convergence sublayer (SSCS: service specific convergence layer).

FIG. 3A is a diagram showing a data format for each layer in the ATM communication system. Here, a user service data unit (U-SDU) of an upper layer passes through an AAL-service access point (AAL-SAP) (AAL-SDU) and stored in the AAL FIFO. The AAL1 SAR layer divides the CS-PDU into 47 bytes according to the message to be transmitted by the user, adds 1 byte of SAR header, Protocol unit (SAR-PDU) is formed and sent down to the ATM layer via the ATM service connection point (ATM-SAP). In the ATM layer, a 5-byte ATM header is attached to form an ATM cell of 53 bytes, and the ATM cell is transmitted to another terminal or an ATM exchange through an optical path of the physical layer.

That is, in the AAL type 1 protocol, the U-SDU of the identity bit rate is transmitted at the same bit rate together with the related time information so that the clock information of the information source can be extracted from the receiving side, and in the converging sub- In the partitioning and reassembling sublayer, the CS-PDU is divided, and a 1-byte header is added and sent down to the ATM layer.

3A shows a SAR format of AAL type 1, wherein the transmitted message is divided into a 47-byte SAR-PDU payload and a 1-byte header, which has 4-bit sequence number protection Sequence number protection (SNP). The sequence number SN consists of a 1-bit convergence sublayer indicator (CSI) and a 3-bit sequence count (SC) The number protection (SNP) is made up of 3 bits of CRC and 1 bit of parity (P).

4A to 4C are diagrams showing a segmentation and reassembly protocol data unit (SAR-PDU) and a pointer segment for structured data transfer, wherein a pointer segment is included in a segmentation and reassembly protocol data unit (SAR-PDU) This is not possible for each of the segmentation and reassembly protocol data units (SAR-PDUs), but the segmentation and reassembly protocol data unit (SAR-PDU) payload segments are coded according to the following rules.

4A and 4B, the P-type (P format) and the non-P format (non P format) are divided into P format The first byte of the segmentation and reassembly protocol data unit (SAR-PDU) payload section is a pointer segment, and its format is configured as shown in FIG. 4C. In addition, the contents of the pointer section shown in FIG. 4C indicate the distance from the end of the pointer section to the start of the first user data block of 93 bytes (in some cases, 94 bytes) Set value. The binary value of this offset is aligned to the right, and the first bit of the pointer interval is used as odd and even check bits.

Also, the P format is only possible if the sequence number of the segmentation and reassembly protocol data unit (SAR-PDU) header is an even number, for example, 0, 2, 4 and 6, and one cycle, i.e., 8 segmentation and reassembly protocol data units SAR-PDU) is transmitted only once. If there is no boundary information during one cycle, a split and reassembly protocol data unit (SAR-PDU) having a header sequence number of 6 is formed in P format, and a dummy pointer having all bits of 1 is formed in the pointer section .

When the segmentation and reassembly protocol data unit (SAR-PDU) is in the P format, the convergence sublayer indicator (CSI) bit of the header is set to 1, and the transmitting side transmits only the convergence sub- (CSI) bits to detect boundary information.

5 is a diagram illustrating an embodiment of a pointer generating apparatus for transferring structured data in the AAL type 1 according to the present invention. In this embodiment, as an upper layer, For example, two frame signals, and uses the constant bit rate (CBR) data for the U-SDU of the upper layer.

The pointer of the present embodiment is composed of 8 bits of data. Of these 8 bits, 7 bits are offset fields, and 1 bit is a reserved bit, for example, a parity check bit. Accordingly, when the user data input from the upper layer, for example, the segmentation and recombination protocol data unit (SAR-PDU) payload data, that is, 93 bytes or 94 bytes, is input to the first and second FIFOs 10 and 11, The pointer generating apparatus 20 according to the present invention generates a pointer of one byte. That is, since the pointer is generated only when the header for the payload of the segmentation and reassembly protocol data unit (SAR-PDU) is 0, 2, 4 and 6, the 6-bit counter 12 outputs 93 bytes ) Or 94 bytes (when no frame signal is detected).

Meanwhile, the user data from the upper layer is inputted and stored into the first and second FIFOs 10 by 8 bits, and the user clock signal from the upper layer is inputted to the first and second FIFOs 10 and 11, And the 6-bit counter 12, respectively. In this case, when two frame signals, that is, first and second frame signals, are input from the upper layer to the controller 18, the controller 15 detects whether a frame signal has been generated and outputs the frame signal to the first and second registers 13 , ≪ / RTI > 14).

The 6-bit counter 12 outputs 6-bit count bits for user data, that is, 16-bit input data, based on the user clock signal, and the 6-bit count bits are input to the first and second registers (13, 14). The first and second registers 13 and 14 are supplied with 0-bit values and 1-bit values, one by one, from the system controller (not shown) Each of which outputs a pointer of 7 bits. Here, the pointer value output from the first register 13 is twice the counter value from the 6-bit counter 12, and the pointer value output from the second register 14 is the 6-bit counter 12, 1 " to " 2 "

Here, the 7-bit pointer from the first and second registers 13 and 14 is output by the enable signal EN from the control unit 18, and this enable signal is output from the first And the second frame signal.

Each of the 7-bit pointers from the first and second registers 13 and 14 is input to the multiplexer 16. The 7-bit pointer is input to the multiplexer 16 by a selection signal from the control unit 18. [ The 7-bit pointer is selectively output from the 7-bit pointer. Thereafter, a 7-bit pointer selected from the multiplexer 16 and an even parity bit of 1 bit from the parity generator 17 are input to the third register 15 so that a pointer of 8-bit structured data transfer (SDT) And the pointer of the 8-bit structured data transfer is outputted by the enable signal from the control unit 18. [

6 shows an apparatus for forming a segmentation and recombination protocol data unit (SAR-PDU) using a pointer generator for transferring structured data in an AAL type 1 according to the present invention, wherein reference numerals 10 and 11 denote a first And a second FIFO, 20 is a pointer generator, and 22 is a multiplexer.

First, when no frame signal is generated, that is, when a pointer is not generated from the pointer generator 20, the multiplexer 22 receives user data, for example, 47 octets from the first and second FIFOs 10 and 11 The payload data of the segmentation and reassembly protocol data unit (SAR-PDU) and the ATM header or the SAR header are input from the system control unit (not shown). Then, the multiplexer 22 forms and outputs a segmentation and reassembly protocol data unit (SAR-PDU) according to a system control signal from the system control unit.

When a frame signal is generated, that is, when a pointer is generated from the pointer generator 20, the multiplexer 22 receives user data, for example, a 46-octet division and reassembly protocol from the first and second FIFOs 10 and 11 Paired load data of a data unit (SAR-PDU) is input, a pointer of 1 byte is input from the pointer generator 20, and an ATM header and a SAR header are input from the system control unit. Then, the multiplexer 22 forms and outputs a segmentation and recombination protocol data unit (SAR-PDU) including a pointer according to a system control signal from the system control unit.

FIG. 7 is a flowchart illustrating an operation of a pointer generation method for transferring structured data in the AAL type 1 according to the present invention. In the first step S1, user data from an upper layer, for example, The payload data of the data unit (SAR-PDU) is inputted to the first and second FIFOs 10 and 11 and then stored and put in the first standby state. In the second step S2, If it is determined that the first and second frame signals for the payload data of the segmentation and reassembly protocol data unit (SAR-PDU) are generated from the upper layer, if the first and second frame signals are not generated The first standby state of the first step S1 is maintained.

In the third step S3, if the first frame signal is generated as a result of the second step S2, the pointer value from the first register 13 is twice the counter value from the 6-bit counter 12 Lt; / RTI > In the fourth step S4, if the second frame signal is generated as a result of the second step S2, the pointer value from the second register is set to 1 twice the counter value from the 6-bit counter 12 The value is set to a summed value.

In the fifth step S5, a pointer for transferring structured data formed of the pointer and the parity bit is stored in the third register 15 and then maintained in the second standby state. In the sixth step S6, the sequence number of the SAR header is detected and it is determined whether or not the current cycle is completed. If the current cycle is not completed, the second standby state of the fifth step S5 is maintained. When the cycle ends, the pointer stored in the third register 15 is outputted and the first standby state of the first step S1 is maintained.

It should be noted that the drawings are not intended to limit the technical scope of the present invention to the embodiments shown in the drawings in order to facilitate understanding of the present invention. In addition, various modifications may be made without departing from the gist of the invention.

As described above, according to the present invention, two 8-bit data, for example, 16-bit data units are input from an upper layer and are formed into a division and reassembly protocol data unit (SAR-PDU) In order to provide information on the user data structure in the data processing apparatus, an 8-bit data bus is used by generating a pointer for transferring structured data using an external signal different from the data bus, for example, two frame signals It is possible to provide the advantage of being able to process structured data at a higher rate than it is possible.

Claims (6)

A counter (12) for counting user data from a user clock from an upper layer and counting user data to calculate an offset field of the pointer; A first register 13 for outputting a count bit twice as large as the count value from the counter 12; A second register (14) for outputting a count bit obtained by adding one to the count value from the counter (12); A multiplexer (16) for selectively outputting count bits from the first and second registers (13, 14); A third register 15 for forming and outputting a pointer by a count bit from the multiplexer 16 and a parity bit from the parity generating means 17; The first and second registers 13 and 14 are selectively enabled by the first and second frame signals from the upper layer and the selection signal is output to the far multiplexer 16, 15. A pointer generator for transferring structured data in an AAL type 1. 2. The method of claim 1, wherein the counter (12) is configured to output a count bit of 6 bits for a duration of the header sequence number of the segmentation and reassembly protocol data unit (SAR-PDU) payload data from 0 to 7, A pointer generator for delivering structured data in AAL type 1. The apparatus of claim 1, wherein the control unit (15) selects only a first frame signal when a plurality of frame signals are input for one cycle. A first step in which user data from an upper layer, such as payload data of a segmentation and recombination protocol data unit (SAR-PDU), is input to the first and second FIFOs 10 and 11, (S1); It is determined whether or not the first and second frame signals for payload data of the segmentation and reassembly protocol data unit (SAR-PDU) in the first step (S1) are generated from the upper layer, and then the first and second A second step (S2) of maintaining the first standby state of the first step (S1) when no frame signal is generated; A third step of setting the pointer value from the first register 13 to a value twice the counter value from the 6-bit counter 12 when the first frame signal is generated as a result of the second step S2 S3); As a result of the second step S2, when the second frame signal is generated, the pointer value from the second register 14 is set to a value twice the counter value from the 6-bit counter 12 plus one (S4); A fifth step (S5) of storing a pointer of structured data transfer formed by the pointer and the parity bit in a third register (15) and then maintaining a second standby state; And the second wait state of the fifth step S5 is maintained if the current cycle is not completed. If the current cycle is terminated, the third register And a sixth step S6 of maintaining a first standby state of the first step S1 after outputting a pointer stored in the pointer 15 to the pointer. 5. The method of claim 4, wherein the pointer value of the first register (13) is composed of 7 bits, and the upper 6 bits are the count bit value from the counter (12) A pointer generation method for transferring structured data in type 1. 5. The method of claim 4, wherein the pointer value of the second register (14) is composed of 7 bits, and the upper 6 bits are the count bit value from the counter (12) A pointer generation method for transferring structured data in type 1.