KR0185862B1 - Apparatus and method for extracting the boundary signal of structured data from the pointer of sdt in aal type 1 - Google Patents

Abstract

In the present invention, a pointer is extracted from payload data of a segmentation and recombination protocol data unit (SAR-PDU) input by 16 bits from the ATM layer and stored, and a pointer is output by an enable signal from the control unit A first register (12) for registering the first register (12); A second register 13 for shifting and storing a pointer from the first register 12 and outputting a pointer bit by an enable signal from the control means 15; A counter 11 for counting the payload data of the segmentation and recombination protocol data unit (SAR-PDU) from the user clock from the ATM layer and outputting count bits for the payload data; Comparison means (14) for comparing a count bit from the counter (11) with a pointer bit from the second register (13) and outputting a boundary signal; An AND gate 16 for outputting a boundary signal by a boundary signal from the comparison means 14 and a control signal from the control means 15; First and second buffers (17, 18) for selectively outputting a boundary signal from the AND gate (16); The first and second registers 12 and 13 are enabled by the cell loss signal and the frame signal is output to the AND gate 16 and the first and second buffers 17 and 18 are And control means (15) for selectively operating the control means.

Description

Boundary signal extracting device from pointer with structured data transfer information in AAL type 1 and its extraction method

The present invention relates to an apparatus and method for extracting a boundary signal from a pointer having structured data transfer information in an AAL type 1, and more particularly, to a method and apparatus for extracting a boundary signal from a pointer, AAL type that can extract the frame signal for the payload data of the payload data of the segmentation and recombination protocol data unit (SAR-PDU) from the payload data of the segmentation and recombination protocol data unit (SAR-PDU), for example, The present invention relates to a boundary signal extracting apparatus and method for extracting a boundary signal from a pointer having structured data transfer information in an image processing apparatus.

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

As a method of processing CBR data in the AAL type 1, data transmission using an 8-bit data bus is performed, and therefore data transmission using a 16-bit data bus is required .

Accordingly, when data is transmitted using a pointer including information of a user data structure, a frame signal for a boundary signal of a user data structure from a pointer including the structured data transmission information input from the reception- A need exists for a device for extracting the liquid.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an apparatus and method for transmitting payload data of a segmentation and reassembly protocol data unit (SAR-PDU) A boundary signal extracting device from a pointer having structured data transfer information in AAL type 1 capable of extracting a frame signal for a boundary signal of payload data of a segmentation and recombination protocol data unit (SAR-PDU) The purpose of this extraction method is to provide.

According to an aspect of the present invention, a pointer is extracted from payload data of a segmentation and reassembly protocol data unit input by 16 bits from an ATM layer, and the pointer is extracted by an enable signal from the control unit. A first register for outputting; A second register for shifting and storing a pointer from the first register and outputting a pointer bit by an enable signal from the control means; A counter for counting the payload data of the segmentation and reassembly protocol data units from the user clock from the ATM layer and outputting count bits for the payload data; Comparison means for comparing a count bit from the counter with a pointer bit from the second register to output a boundary signal; An AND gate for outputting a boundary signal by a boundary signal from the comparison means and a control signal from the control means; First and second buffers for selectively outputting a boundary signal from the end gate; And control means for enabling the first and second registers by the cell loss signal, outputting the frame signal to the AND gate, and selectively operating the first and second buffers.

The present invention constructed as described above is divided from a pointer having information on payload data of a segmentation and reassembly protocol data unit (SAR-PDU) input from the ATM layer in units of 16 bits, for example, structural data from user data And the frame signal for the boundary signal of the payload data of the re-association protocol data unit (SAR-PDU).

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 showing an embodiment of a boundary signal extracting apparatus from a pointer having structural data transfer information in AAL type 1 according to the present invention,

6 is a flowchart illustrating a method of extracting a boundary signal from a pointer having structural data transfer information in the AAL type 1 according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

10: FIFO 11: 6-bit counter

12, 13: first and second registers 14:

15: control unit 16: AND gate

17, 18: first and second buffers 20: boundary signal extractor

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 (SAR-PDU). The first byte of the payload interval is a pointer interval, and its format is 93 bytes after the end of the pointer interval (in some cases 94 Byte) is the offset value of the distance from the start of the first user data block in octets. 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, a 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 showing an embodiment of a boundary signal extracting apparatus from a pointer having structured data transfer information in the AAL type 1 according to the present invention. In this embodiment, a signal including the boundary of the data structure from the ATM layer (CBR) data is used as a user data service unit (ATM-SDU) of the ATM 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.

5, first, the controller 15 extracts and inspects pointers among the payload data of the segmentation and reassembly protocol data unit (SAR-PDU) input from the ATM layer through the first register 12, And whether or not it has occurred and whether or not it has a null pointer is checked and stored in the first register 12 only in a normal case. The first register 12 stores only 7 bits of pointer bits except for the least significant 1 bit among the input 8 bits of pointer bits, and outputs a pointer according to an enable signal from the controller 15.

In addition, the second register 13 shifts and stores 7-bit pointer bits from the first register 12, and outputs pointer data according to an enable signal from the control unit 15. [ The second register 13 detects a 1-bit parity bit among 7-bit pointer bits, outputs the parity bit to the controller 15, and outputs a 6-bit pointer bit.

On the other hand, the 6-bit counter 11 counts the payload data of the segmentation and recombination protocol data unit (SAR-PDU) from the user clock from the ATM layer and outputs a count bit of 6 bits. Therefore, the comparator 14 compares the count bit from the 6-bit counter 11 and the 6-bit pointer bit from the second register 13 every clock to calculate an output value, And a second frame signal, e.g., a border signal, are selectively output.

Here, the comparator 14 outputs a value of 1 when a pointer bit is generated while comparing the pointer bit from the second register 13 every clock, and when the value of 1 is output, The first and second frame signals are selectively output depending on whether the pointer bits are even or odd.

If a cell loss occurs during the comparison, the control unit 15 inputs a value of 0 into the AND gate 16 to block the output of the frame signal and then terminates the current cycle And if a frame signal has already occurred in the current cycle, generation of a further frame signal is suppressed. In this way, the control unit 15 enables the first and second registers 12 and 13 according to the cell loss signal, and outputs the frame signal to the AND gate 16.

However, when the frame signal is generated several times in one cycle due to the malfunction of the ATM layer, the problem is recognized. In this case, the pointer is stored in the register .

Meanwhile, while the input data from the ATM layer is input and stored in the FIFO 10 by 16 bits, the user clock signal from the ATM layer is input to the 6-bit counter 11 of the FIFO 10 and the boundary signal extractor 20, And the cell loss signal is input from the ATM layer to the control unit 15. [

If there is a pointer after confirming the existence of a pointer from the header of the segmentation and reassembly protocol data unit (SAR-PDU) input to the FIFO 10, the pointer is extracted and the cell loss signal It is checked whether or not an error has occurred and whether or not a null pointer is present, and the result is stored in the first register 12 only in a normal case. Accordingly, when no error has occurred, the control unit 15 shifts the 7-bit point bit to the second register 13 by the enable signal EN.

In addition, after generating the frame signal, that is, the boundary signal, it is in a waiting state until the current cycle ends. After that, when the current cycle ends, the new state is obtained and the new pointer is extracted. Further, when the frame signal is extracted, the frame signal is not generated and immediately becomes a standby state.

6 is a flowchart illustrating an operation of a method of extracting a boundary signal from a pointer having structured data transfer information in the AAL type 1 according to the present invention. In the first step S1, The pointer is extracted from the payload data of the reassociation protocol data unit (SAR-PDU) and is stored in the first register 12.

In the second step S2, the controller 15 determines whether there is an error or a null pointer in the pointer stored in the first register 12 due to the cell loss signal, If there is an occurrence or a null pointer, the flow advances to the ninth step (S9) to maintain the standby state.

If the pointer is not a null pointer or a null pointer in the second step S2, the third step S3 is to set the 6-bit count bit for the user data output from the 6-bit counter 11, And compare the pointer bits [6: 1] from the two registers 13 with each other. In the fourth step S4, it is determined whether or not a cell loss has occurred as a result of the comparison in the third step S3. If it is determined that a cell loss has occurred, the process moves to the ninth step S9, .

In the fifth step S5, if the cell loss does not occur as a result of the fourth step S4, the count bit of 6 bits for the user data output from the 6-bit counter 11 and the count bit of the second register 13), and the sixth step S6 determines whether or not the value of the pointer [0] is 0 when the result of the determination in the fifth step (S5) is coincident.

In the seventh step S7, a boundary signal is generated from the first frame signal when the value of the pointer [0] is 0 as a result of the determination in the sixth step S6. In the eighth step S8, As a result of the determination in step S6, if the value of the pointer [0] is not 0, a boundary signal is generated from the second frame signal. In the ninth step S9, after the generation of the frame signal in the seventh and eighth steps S7 and S8, the current cycle is terminated until the current cycle ends.

In the tenth step (S10), it is determined whether or not the current cycle is completed after the waiting state of the ninth step (S9). If the determination result is not finished, the waiting state of the ninth step (S9) is maintained, The process goes to the first step S1.

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, since the payload data of the segmentation and reassembly protocol data unit (SAR-PDU) input in units of 16 bits from the ATM layer, for example, from the pointer having the information on the structural data transfer from the user data The frame signal for the boundary signal of the payload data of the segmentation and reassembly protocol data unit (SAR-PDU) can be extracted.

Claims (6)

A first register for extracting and storing pointers among payload data of division and reassembly protocol data units (SAR-PDU) input by 16 bits from the ATM layer and for outputting pointers by an enable signal from the control unit 15; (12); A second register 13 for shifting and storing a pointer from the first register 12 and outputting a pointer bit by an enable signal from the control means 15; A counter 11 for counting the payload data of the segmentation and recombination protocol data unit (SAR-PDU) from the user clock from the ATM layer and outputting count bits for the payload data; Comparison means (14) for comparing a count bit from the counter (11) with a pointer bit from the second register (13) and outputting a boundary signal; An AND gate 16 for outputting a boundary signal by a boundary signal from the comparison means 14 and a control signal from the control means 15; First and second buffers (17, 18) for selectively outputting a boundary signal from the AND gate (16); The first and second registers 12 and 13 are enabled by the cell loss signal and the frame signal is output to the AND gate 16 and the first and second buffers 17 and 18 are And a control unit (15) for selectively operating the AAL type 1 and the AAL type 1. The apparatus for extracting a boundary signal from a pointer having structured data transfer information in an AAL type 1. 2. The method according to claim 1, wherein the comparing means (14) compares the pointer bit from the second register (13) every clock and outputs a value of 1 when a pointer bit is generated An apparatus for extracting a boundary signal from a pointer having structural data transfer information. 2. The apparatus of claim 1, wherein the control unit (15) extracts and inspects pointers from payload data of a segmentation and reassembly protocol data unit (SAR-PDU) input from the ATM layer and determines whether an error occurs, , And stores the data in the first register (12) only in a normal case. 2. The apparatus according to claim 1, wherein the control means (15) controls the first and second buffers (17, 18) in accordance with whether the pointer bit is even or odd, And outputs a selection signal to selectively output the first and second frame signals. The apparatus for extracting a boundary signal from a pointer having structured data transfer information in an AAL type 1. 2. The method according to claim 1, wherein the control means (15) inputs a value of 0 into the AND gate (16) to prevent generation of an erroneous frame signal when a cell loss occurs during the comparison by the comparison means And the output of the frame signal is cut off. The apparatus for extracting a boundary signal from a pointer having structured data transfer information in an AAL type 1. A first step (S1) of extracting a pointer from payload data of a segmentation and recombination protocol data unit (SAR-PDU) input from the ATM layer and storing the extracted pointer in the first register (12); The control unit 15 determines whether an error has occurred and whether or not an error has occurred in the pointer stored in the first register 12 due to the cell loss signal. If it is determined that there is an error in the pointer or a null pointer, A second step S2 of moving to step S9 and maintaining the standby state; In the second step S2, if a pointer error occurs or if it is not a null pointer, the 6-bit count bit for the user data output from the counter 11 and the pointer bit [6: 1 A third step S3 of comparing the received data with the received data; A fourth step S4 of determining whether or not a cell loss has occurred as a result of the comparison in the third step S3 and, if a cell loss has occurred, moving to the ninth step S9, ; If it is determined in the fourth step S4 that no cell loss has occurred, the 6-bit count bit for the user data output from the 6-bit counter 11 and the pointer bit from the second register 13 match (S5); A sixth step (S6) of judging whether or not the value of the pointer [0] is 0 when it is determined as a result of the fifth step (S5); A seventh step (S7) of generating a boundary signal from the first frame signal when the value of the pointer [0] is 0 as a result of the determination in the sixth step (S6); An eighth step (S8) of generating a boundary signal from the second frame signal when the value of the pointer [0] is not 0 as a result of the determination in the sixth step (S6); A ninth step (S9) of maintaining a standby state until a current cycle is completed after generation of a frame signal in the seventh and eighth steps (S7, S8); After the waiting state of the ninth step S9, it is determined whether or not the current cycle is ended. If the determination result is not completed, the waiting state of the ninth step S9 is maintained. If the current cycle is finished, the process goes to the first step S1 (10). The method of extracting a boundary signal from a pointer having structured data transfer information in an AAL type 1.