KR100497868B1 - Apparatus And Method For Converting AAL2/AAL5 - Google Patents

Abstract

According to the present invention, in converting ATM Adaptation Layer (AAL) 2 and AAL5, SEG-SSCS (SEGmentation and reassembly Service Specific Convergence Sublayer) of AAL2 without making AAL2 SSTED-SDU (Service Specific Transmission Error Detection sublayer-Service Data Unit) The present invention relates to an AAL2 / AAL5 conversion device and a method for enabling the implementation of the SSTED function, which is a layer.

According to the present invention, in converting AAL2 and AAL5, the AAL2 SSTED function is implemented without performing a full AAL2 SSTED-SDU to perform mutual conversion, thereby not storing the entire user data for one AAL2 / AAL5 conversion. Since only the portion corresponding to the AAL2 CPS packet of the AAL2 CPS packet needs to be stored, the required memory resource can be reduced to a maximum of 128 bytes, and the transmission delay time can be reduced by minimizing the amount of data to be stored during mutual conversion.

Description

ALA2 / AL5 converting device and method thereof {Apparatus And Method For Converting AAL2 / AAL5}

The present invention relates to the interconversion of AAL (ATM Adaptation Layer) 2 and AAL5, in particular without creating AAL2 SSTED-SDU (Service Specific Transmission Error Detection sublayer-Service Data Unit) SEG-SSCS (SEGmentation and reassembly Service Specific) The present invention relates to an AAL2 / AAL5 conversion device and a method for enabling the implementation of the SSTED function, which is one layer of the convergence sublayer.

Recently, a mobile communication system employing the CDMA-2000 system guarantees access to various multimedia media including not only voice information but also image and packet data information. Data processing is taking place.

However, when data transmission is performed between the base station and the control station, the control station, and CAN (Central ATM Network) via AAL5, the data area is transmitted as the data is transmitted in units of cells (53 bytes; header 5 bytes and data 48 bytes). Even if there are empty bytes, for example, if a small amount of data (voice or text, etc.) is loaded and transmitted, the empty bytes must be transmitted as they are, resulting in inefficiency in circuit usage.

Accordingly, in the conventional CDMA-2000 system, as shown in FIG. 1, the base station 10 serving as a network element and the control station 20 perform data processing through AAL5. However, the base station 10 Data transmission is performed between the control station 20, the control station 20, and the CAN 30 through AAL2. For this purpose, AAL2 / AAL5 converts AAL2 and AAL5 into each network element. The converter 40 is provided.

Here, the protocol layer of AAL2 for data transmission between network elements is as shown in Figure 2 attached to the sub-layer SSADT (Service Specific Assured Data Transfer sublayer) function that guarantees reliability, such as data retransmission And a Service Specific Transmission Error Detection sublayer (SSTED) sublayer that provides error detection, and a Service Specific Segmentation And Reassembly sublayer (SSSSAR) sublayer that functions to partition data from an upper layer and reassemble data from a lower layer. It consists of a CPS sublayer multiplexing the CPS-SDU (Common Part Sublayer-Service Data Unit) received on 48 bytes forming a payload.

In addition, the structure of the SSTED sublayer, which is a layer of the SEG-SSCS in FIG. 2, is a form in which an SSTED-SDU, that is, an SSTED-PDU trailer is attached to an SSTED-PDU payload as shown in FIG. 3. SSTED trailers include SSTED-UU (User to User interface; 1 octet), Reserved (Reserved Filed; 6 bit), CI (Congestion Indication; 1 bit), LP (Loss Priority; 1 bit), Length (Length; 2 octets), cyclic redundancy check (CRC), etc., where the length and CRC can be calculated only if there is a full SSTED-PDU payload, that is, a full SSTED-SDU.

Therefore, when the SSTED-SDU is transmitted from a higher level to an SSTED sublayer as a complete message instead of being delivered at once, but at a time interval, the SSTED sublayer configures one SSTED-SDU for the length and CRC calculation. Previously arrived messages must be stored in a separate memory until the last message arrives.

In this regard, the conventional AAL2 / AAL5 conversion device 40 has an AAL2 CPS receiver 41a, an AAL2 SSSAR receiver 42a, and AAL2 to convert AAL2 to AAL5, as shown in FIG. A SSTED receiver 43a, an AAL5 CPCS transmitter 44a, an AAL5 SAR transmitter 45a and memory units 46a, 47a are provided, and an AAL5 SAR receiver 41b and AAL5 are used to convert AAL5 to AAL2. A CPCS receiver 42b, an AAL2 SSTED transmitter 43b, an AAL2 SSSAR transmitter 44b, an AAL2 CPS transmitter 45b, and memory units 46b, 47b are provided.

Here, a description will be given of the conventional operation of converting AAL2 and AAL5 to each other. First, an operation of converting AAL2 to AAL5 and processing is performed as shown in FIGS. 5 and 6. When 48 48-byte ATM payloads, i.e., AAL2 ATM cells are received (step S51), the AAL2 CPS receiver 41a extracts the AAL2 CPS packets from the ATM payload (step S52), and then the CPS packet header in the corresponding AAL2 CPS packets. The CPS packet payload, i.e., the CPS-SDU, is transferred to the upper AAL2 SSSAR receiver 42a. To this end, the AAL2 CPS receiver 41a has a memory 46a for each VPI / VCI (Virtual Path Identifier / Virtual Channel Identifier).

Then, one or several CPS-SDUs delivered from the AAL2 CPS receiver 41a are assembled into one SSSAR-SDU by the AAL2 SSSAR receiver 42a and then transferred to the upper AAL2 SSTED receiver 43a, where AAL2 The SSSAR receiver 42a checks whether the CPS-SDU currently delivered from the lower AAL2 CPS receiver 41a is the last part of the AAL2 SSSAR (step S53), and the corresponding CPS-SDU until the last part of the AAL2 SSSAR is delivered. Is stored in a separate memory section 47a and managed (step S54). To this end, the AAL2 SSSAR receiver 42a has a memory 47a for storing the AAL2 CPS-SDU for each VPI / VCI / CID (Channel ID).

Subsequently, when the AAL2 SSSAR receiving unit 42a receives the CSP-SDU corresponding to the last part of the AAL2 SSSAR, the AAL2 SSSAR receiving unit 42a assembles the CPS-SDUs received so far into one AAL2 SSSAR-SDU (step S55), and the upper part thereof. The AAL2 SSTED receiver 43a is transferred to the receiver 43a.

The AAL2 SSTED receiving unit 43a that receives the SSSAR-PDU from the AAL2 SSSAR receiving unit 42a extracts the SSTED-PDU payload, that is, the SSTED-SDU from which the SSTED trailer is removed from the SSSAR-PDU, and delivers the SSTED-SDU to the upper AAL5 layer. (Steps S56, S57).

At this time, when the AAL5 CPCS transmitter 44a implemented in the AAL5 layer receives the AAL2 SSTED-SDU from the AAL2 SSTED receiver 43a (step S61), the AAL5 CPCS transmitter 44a makes the AAL5 CPCS-SDU and transfers it to the AAL5 SAR transmitter 45a. (Step S62), the AAL5 SAR transmitter 45a attaches the CPCS-PDU trailer to the AAL5 CPCS-SDU and transmits it to the counterpart through the ATM layer through the SAR process, where the AAL5 SAR transmitter 45a sends the AAL5 CPCS-SDU to the AAL5 CPCS-SDU. The AAL5 CPCS-PDU to which the CPCS-PDU trailer is attached is divided into ATM-SDUs, and then transmitted to the ATM layer (steps S63 and S64).

The operation of transmitting the ATM-SDU to the ATM layer checks whether the currently transmitted ATM-SDU is the last ATM-SDU (step S65), and converts the AAL5 CPCS-PDU to the ATM-SDU until the last ATM-SDU is transmitted. The operation of dividing and transmitting is repeatedly performed.

Meanwhile, the operation of converting AAL5 into AAL2 and processing the AAL2 / AAL5 conversion device 40 in the related art may be performed in the opposite manner to the operation of converting and converting AAL2 into AAL5.

As described above, in order to convert AAL2 and AAL5 to each other, a large amount of memory is required for AAL2 SSSAR and AAL5 SAR, and length information of AAL2 SSTED and AAL5 CPCS is composed of 16 bits. There are disadvantages in terms of economics as 64 Kbytes of memory are required each. Also, because the whole data must be waited to perform AAL2 SSSAR, transmission delay time increases, which is very disadvantageous for real-time service. There was a problem.

The present invention is to solve the problems described above, the purpose of the AAL2 and AAL5 to convert the AAL2 SSTED function without implementing the AAL2 SSTED-SDU without making a complete AAL2 SSTED function can perform the corresponding cross-conversion A / AAL5 conversion apparatus and method are provided.

Another object of the present invention is to implement the AAL2 SSTED function without making a complete AAL2 SSTED-SDU to perform AAL2 and AAL5 cross conversion, thereby significantly reducing the memory resources required for cross conversion of up to 128 bytes.

Another feature of the present invention is to reduce the transmission delay time by minimizing the amount of data to be stored during AAL2 and AAL5 conversion.

A feature of the present invention for achieving the above object is an AAL2 CPS receiver for extracting the AAL2 CPS packet from the AAL2 ATM cell received from the lower ATM layer and forwards it along with the AAL2 CPS packet UUI; After checking whether the AAL2 CPS packet transmitted from the AAL2 CPS receiver is the last part of the AAL2 SSSAR, and checking whether it can be one ATM-SDU, the AAL2 SSTED length and CRC for the AAL2 CPS packet, and the AAL5 CPCS length and CRC An AAL5 CPCS & SAR transmitter for calculating and storing the AAL2 CPS packet into an ATM-SDU and transmitting it to the counterpart; When the AAL5 cell is received, it separates the user data and checks whether it is the last cell.In the case of the last cell, the AAL2 SSTED length and CRC are calculated and passed along with the user data.If the cell is not the last cell, the AAL5 cell is temporarily stored in the third memory unit. An AAL5 CPCS & SAR receiver for calculating the AAL2 SSTED length and the CRC after combining the data stored in the third memory unit with the user data when the last cell is received; The present invention provides an AAL2 / AL5 conversion apparatus including an AAL2 CPS transmitter configured to transmit an AAL2 CPS packet to an ATM layer after generating data received from the AAL5 CPCS & SAR transmitter.

The AAL2 CPS receiving unit may temporarily store AAL2 data that has not completed the AAL2 CPS packet in the first memory unit until the next AAL2 CPS packet is extracted.

And, if the AAL5 CPCS & SAR transmitter fails to make the AAL2 CPS packet into an ATM-SDU, the last AAL2 CPS packet is calculated by calculating the AAL2 SSTED length and CRC, and the AAL5 CPCS length and CRC to the remainder of the AAL2 CPS packet and the present. Is stored in the second memory unit until the last AAL2 CPS packet is received, the AAL2 SSTED PDU trailer is removed, the total AAL5 CPCS length and CRC are calculated, and the final ATM-SDU is transmitted to the counterpart through the ATM layer. Characterized in that.

In addition, the AAL5 CPCS & SAR transmitter, if the last AAL2 CPS packet is received, characterized in that the total AAL2 SSTED length and CRC to check whether there is an error.

If the next received cell is not the last cell, the AAL5 CPCS & SAR receiver calculates the AAL2 SSTED length and the CRC and the AAL5 CPCS length and the CRC only for the user data stored in the third memory. Only the AAL2 SSTED length and the CRC and the AAL5 CPCS length and the user data that is not transmitted along with the CRC is temporarily stored in the third memory until the next cell arrives.

The AAL2 CPS transmitter may temporarily store the remaining AAL2 CPS packet, which is not completed in an ATM cell, in a fourth memory unit.

Another feature of the present invention is the AAL2 CPS receiver extracts an AAL2 CPS packet from an AAL2 ATM cell received from a lower ATM layer, and then delivers the AAL2 CPS packet together with the AAL2 CPS packet UUI to the AAL5 CPCS & SAR transmitter; Checking, by the AAL5 CPCS & SAR transmitter, whether the AAL2 CPS packet UUI included in the AAL2 CPS packet is the last part of the AAL2 SSSAR; Creating an AAL5 CPCS-PDU after calculating the final AAL2 SSTED length and CRC if it is identified as the last part of the AAL2 SSSAR; The AAL5 CPCS-PDU for the AAL5 CPCS length and CRC to calculate the final ATM-SDU to the ATM layer including the step of transmitting to the ATM layer to provide a conversion method.

In addition, the above-described A2 / A5 conversion method checks whether the corresponding AAL2 CPS packet can be made into an ATM-SDU when checking that the AAL2 CPS packet UUI is not the last part of the AAL2 SSSAR. Process; If the ATM-SDU can be made, further comprising the step of making the corresponding AAL2 CPS packet into the AAL5 CPCS-PDU, and splitting it into ATM-SDUs through the SAR process to the ATM layer. If the packet cannot be made into an ATM-SDU, the AAL2 SSTED length and CRC of the remainder of the corresponding AAL2 CPS packet and the present are calculated, and the AAL5 CPCS length and CRC are calculated and stored in the second memory unit. It is characterized by including.

On the other hand, in the above-described A2 / A5 conversion method, the process of creating the AAL5 CPCS-PDU, when the last AAL2 CPS packet is received, the length of the last AAL2 CPS packet to the AAL2 SSTED length stored in the second memory unit Adding to determine the error after calculating the final AAL2 SSTED length and CRC; Removing the AAL2 SSTED trailer from the AAL2 SSTED-PDU and attaching the AAL5 CPCS-PDU trailer to create an AAL5 CPCS-PDU.

Another feature of the present invention, the AAL5 CPCS & SAR receiving unit when the AAL5 ATM cell is received if the user data to determine whether the last cell; Calculating the AAL2 SSTED length and the CRC when the terminal is identified as the last AAL5 ATM cell, and transmitting the same to the AAL2 CPS transmitter together with the user data; The AAL2 CPS transmitter provides an AAL2 / AL5 conversion method including a step of making an AAL2 CPS packet to a lower ATM layer.

The above-described A2 / A5 conversion method includes the steps of: storing user data in a third memory unit when the AAL5 ATM cell is not the last cell and waiting for the next AAL5 ATM cell to be received; When the next AAL5 ATM cell is received, determining whether the cell is the last cell; Next, when the received AAL5 ATM cell is identified as the last cell, calculating the AAL2 SSTED length and the CRC by combining the user data stored in the third memory unit and transmitting the AAL2 ATM cell to the AAL2 CPS transmitter together with the user data; The AAL2 CPS transmitter further comprises the step of making an AAL2 CPS packet and transmitting it to the lower ATM layer.

Furthermore, the above-described ALA2 / AL5 conversion method includes the AAL2 SSTED length, CRC, and AAL5 CPCS only for user data stored in the third memory unit when the next received AAL5 ATM cell is not the last cell. Transmitting only user data to the AAL2 CPS transmitter after calculating the length and the CRC; The AAL2 CPS transmitter generates an AAL2 CPS packet and transmits the AAL2 CPS packet to the lower ATM layer, and transmits the AAL2 SSTED length and CRC calculated by the AAL5 CPCS & SAR receiver and the user data not transmitted together with the AAL5 CPCS length and CRC to the next AAL5 cell. The method may further include storing the third memory unit until receiving the received data.

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

In the apparatus for converting between AAL2 and AAL5 according to the present invention, the AAL2 SSTED function and the AAL2 SSSAR function are to be performed in the AAL5 CPCS layer. An AAL2 / AAL5 conversion device 70 for this purpose is shown in FIG. 7. Similarly, an AAL2 CPS receiver 71, an AAL5 CPCS & SAR transmitter 72, and memory units 71-1 and 72-1 for storing respective data are provided for converting AAL2 into AAL5. In order to convert AAL5 into AAL2, an AAL5 CPCS & SAR receiver 73, an AAL2 CPS transmitter 74, and memory units 73-1 and 74-1 for storing respective data are provided.

Here, the AAL2 CPS receiver 71 extracts the AAL2 CPS packet from the ATM payload received from the lower ATM layer, and then, together with the AAL2 CPS packet UUI indicating whether or not it is the last part of the AAL2 SSSAR, the AAL5 CPCS & SAR transmitter 72 The AAL2 data for which the complete AAL2 CPS packet is not completed is temporarily stored in the first memory unit 71-1.

The AAL5 CPCS & SAR transmitter 72 checks whether the AAL2 CPS packet is the last part of a complete AAL2 SSSAR, and also checks whether it can be a single ATM-SDU, and then makes the corresponding AAL2 CPS packet an ATM-SDU to create an ATM layer. The AAL2 SSTED length and CRC, and the AAL5 CPCS length and CRC for the corresponding AAL2 CPS packet are calculated and stored in the second memory unit 72-1. If the AAL2 CPS packet is not made into a complete ATM-SDU, the remaining AAL2 CPS packet, the AAL2 SSTED length and the CRC, and the AAL5 CPCS length and the CRC are calculated until the last AAL2 CPS packet is received. 2 is stored in the memory unit 72-1, and when the last AAL2 CPS packet is received, the total AAL2 SSTED length and CRC are calculated to check for errors, and then the AAL2 SSTED PDU trailer is removed to calculate the total AAL5 CPCS length and CRC. It is made into the last ATM-SDU and transmitted to the other side through the ATM layer.

When the AAL5 cell is received, the AAL5 CPCS & SAR receiver 73 separates user data and checks whether the cell is the last cell, and in the case of the last cell, calculates the AAL2 SSTED length and CRC to the AAL2 CPS transmitter 74 together with the data. To pass. However, if it is not the last cell, it is temporarily stored in the third memory unit 73-1, and when the last cell is received, the AAL2 SSTED length and the sum of the data stored in the third memory unit 73-1 are combined. The CRC is calculated and delivered to the AAL2 CPS transmitter 74 with data. If the next received cell is not the last cell, only the AAL2 SSTED length and the CRC are stored for the data stored in the third memory unit 73-1. After calculating the AAL5 CPCS length and CRC, only data is transmitted to the AAL2 CPS transmitter 74. At this time, the data not transferred together with the AAL2 SSTED length and CRC and AAL5 CPCS length and CRC calculated above are temporarily stored in the third memory unit 73-1 until the next cell arrives.

The AAL2 CPS transmitter 74 converts the data received from the AAL5 CPCS & SAR transmitter 72 into an AAL2 CPS packet, completes it with an ATM cell, and transmits it to the ATM layer. Temporarily stored in the unit 74-1.

In this case, as shown in FIG. 8, the second memory unit 72-1 and the third memory unit 73-1 include AAL2 SSTED length, AAL2 SSTED CRC information, and AAL5 CPCS. Length and AAL5 CPCS CRC information, and user data (up to 64 bytes) are stored.

An operation of converting and processing AAL2 into AAL5 in the above-described configuration will now be described with reference to FIG. 9.

In the present invention, when the AAL2 CPS receiving unit 71 constituting the AAL2 / AAL5 converting apparatus 70 receives the AAL2 ATM cell from the lower ATM layer (step S91), the AAL2 CPS in the payload portion of the currently received AAL2 ATM cell. After extracting the packet (step S92), the AAL2 CPS packet UUI indicating whether or not the corresponding AAL2 CPS packet is the last part of the AAL2 SSSAR is transmitted to the AAL5 CPCS & SAR transmitter 72 belonging to the upper AAL5 CPCS layer.

Then, the AAL5 CPCS & SAR transmitter 72 checks whether the corresponding AAL2 CPS packet is the last part of the complete AAL2 SSSAR by checking the AAL2 CPS packet UUI included in the currently received AAL2 CPS packet (step S93). At this time, if it is not the last part of the AAL2 SSSAR, it is checked whether the corresponding AAL2 CPS packet can be made into one ATM SDU, that is, the length of the AAL2 CPS packet is 48 bytes or more (step S94).

At this time, when it is determined that the AAL2 CPS packet can be made into one ATM SDU, the AAL5 CPCS & SAR transmitter 72 makes the currently received AAL2 CPS packet into the AAL5 CPCS-PDU (step S95), and corresponding AAL5 CPCS The PDU is divided into ATM-SDUs through the SAR process and then transmitted to the ATM layer (step S96).

However, if it is determined in step S94 that the AAL2 CPS packet cannot be made into one ATM-SDU, the AAL5 CPCS & SAR transmitter 72 determines that the corresponding AAL2 CPS packet, that is, the rest of the AAL2 CPS packet and the AAL2 SSTED to date. The length and the CRC are calculated, and the AAL5 CPCS length and the CRC are calculated and stored in the second memory unit 72-1, which is stored in the second memory unit 72-1 until the last AAL2 CPS packet is received. (Step S97).

On the other hand, when the AAL2 CPS packet currently received in step S93 is confirmed to be the last part of the complete AAL2 SSSAR, that is, when the last AAL2 CPS packet is received, the AAL5 CPCS & SAR transmitter 72 is currently in the second memory unit 72. After calculating the final AAL2 SSTED length and CRC by adding the length of the last AAL2 CPS packet to the AAL2 SSTED length stored in -1), it is checked whether there is an error.

Then, the AAL5 CPCS & SAR transmitter 72 removes the AAL2 SSTED trailer from the corresponding AAL2 SSTED-PDU, attaches the AAL5 CPCS-PDU trailer to create an AAL5 CPCS-PDU (steps S98, S99), and the corresponding AAL5 CPCS length. And ACR2 is calculated and the final ATM-SDU is generated and transmitted to the ATM layer (step S100), whereby AAL2 / AAL5 conversion is performed for AAL2 SSTED user data.

In contrast, the operation of converting AAL5 to AAL2 and processing is similar to the operation of converting AAL2 to AAL5 described above. First, when the AAL5 ATM cell is received by the AAL5 CPCS & SAR receiver 73, the AAL5 CPCS & SAR receiver 73 separates the user data to see if it is the last cell.

At this time, if the currently received AAL5 ATM cell is the last cell, the AAL5 CPCS & SAR receiver 73 calculates the AAL2 SSTED length and CRC and transmits the AAL2 CPS transmitter 74 to the AAL2 CPS transmitter 74 along with the user data. In the AAL2 CPS packet, the packet is transmitted to the lower ATM layer.

However, if the currently received AAL5 ATM cell is not the last cell, the AAL5 CPCS & SAR receiver 73 stores the corresponding user data in the third memory 73-1 and waits for the next AAL5 ATM cell to be received. do.

Subsequently, when the next AAL5 ATM cell is received, it is checked whether the corresponding AAL5 ATM cell is the last cell, and if it is confirmed as the last cell, the AAL2 SSTED length is added together with the data previously stored in the third memory unit 73-1. And after calculating the CRC and transmits it with the data to the AAL2 CPS transmitter 74, at this time, the AAL2 CPS transmitter 74 is made as an AAL2 CPS packet and transmitted to the lower ATM layer.

However, if the corresponding AAL5 ATM cell is not the last cell, only the data after calculating the AAL2 SSTED length and CRC, and the AAL5 CPCS length and CRC for the data stored in the third memory unit 73-1, only the data is AAL2 CPS. In this case, the AAL2 CPS transmitter 74 converts the AAL2 CPS packet into an AAL2 CPS packet and transmits the same to the lower ATM layer, and the AAL5 CPCS & SAR receiver 73 calculates the AAL2 SSTED length and the CRC. The data not transmitted together with the AAL5 CPCS length and the CRC is stored in the third memory unit 73-1 until the next AAL5 ATM cell is received.

In addition, the embodiments according to the present invention are not limited to the above-described embodiments, and various alternatives, modifications, and changes can be made within the scope apparent to those skilled in the art.

As described above, in the present invention, in converting AAL2 and AAL5, the AAL2 SSTED function is implemented without performing a full AAL2 SSTED-SDU to perform mutual conversion, thereby storing the entire user data for AAL2 / AAL5 conversion. Rather than storing only the portion corresponding to one AAL2 CPS packet, the required memory resources can be reduced to a maximum of 128 bytes. Also, the transmission delay time can be reduced by minimizing the amount of data stored during the conversion.

1 illustrates a CDMA-2000 system consisting of network elements with a conventional AAL2 / AAL5 converter.

FIG. 2 is a diagram illustrating a protocol layer of AAL2 for data transmission between network elements in FIG. 1; FIG.

FIG. 3 is a diagram illustrating an SSTED sublayer, which is one layer of SEG-SSCS in FIG. 2; FIG.

FIG. 4 is a diagram showing the detailed configuration of an AAL2 / AAL5 converter in FIG. 1; FIG.

5 and 6 are flowcharts showing an operation of converting and processing AAL2 into AAL5 in the conventional AAL2 / AAL5 conversion device.

7 is a diagram showing a detailed configuration of an AAL2 / AAL5 conversion device according to the present invention.

FIG. 8 is a diagram showing details of information stored in a second memory unit and a third memory unit in FIG.

9 is a flowchart illustrating an operation of converting AAL2 into AAL5 and processing the AAL2 / AAL5 conversion apparatus according to the present invention.

Explanation of symbols on main parts of the drawing

70: AAL2 / AAL5 converter 71: AAL2 CPS receiver

72: AAL5 CPCS & SAR transmitter 73: AAL5 CPCS & SAR receiver

74: AAL2 CPS transmitter 71-1, 72-1, 73-1, 74-1: memory

Claims (13)

An AAL2 CPS receiver for extracting an AAL2 CPS packet from an AAL2 ATM cell received from a lower ATM layer and transferring the AAL2 CPS packet together with the AAL2 CPS packet UUI; After checking whether the AAL2 CPS packet transmitted from the AAL2 CPS receiver is the last part of the AAL2 SSSAR, and checking whether it can be one ATM-SDU, the AAL2 SSTED length and CRC for the AAL2 CPS packet, and the AAL5 CPCS length and CRC An AAL5 CPCS & SAR transmitter for calculating and storing the AAL2 CPS packet into an ATM-SDU and transmitting it to the counterpart; When the AAL5 cell is received, it separates the user data and checks whether it is the last cell.In the case of the last cell, the AAL2 SSTED length and CRC are calculated and passed along with the user data.If the cell is not the last cell, the AAL5 cell is temporarily stored in the third memory unit. An AAL5 CPCS & SAR receiver for calculating the AAL2 SSTED length and the CRC after combining the data stored in the third memory unit with the user data when the last cell is received; And an AAL2 CPS transmitter for converting the data received from the AAL5 CPCS & SAR transmitter into an AAL2 CPS packet to complete an ATM cell and transmit the data to an ATM layer. The method of claim 1, And the AAL2 CPS receiving unit temporarily stores AAL2 data that has not completed the AAL2 CPS packet in the first memory unit until the next AAL2 CPS packet is extracted. The method of claim 1, If the AAL5 CPCS & SAR transmitter fails to make an AAL2 CPS packet into an ATM-SDU, the last AAL2 CPS packet is received by calculating the AAL2 SSTED length and CRC, the remaining AAL2 CPS packet, and the AAL5 CPCS length and CRC. To the second memory, and when the last AAL2 CPS packet is received, remove the AAL2 SSTED PDU trailer to calculate the total AAL5 CPCS length and CRC, make it the last ATM-SDU, and send it to the other party through the ATM layer. A2 / A5 converter characterized by the above-mentioned. The method of claim 3, wherein The AAL5 CPCS & SAR transmitter, when the last AAL2 CPS packet is received, the AAL2 / ALS5 converter, characterized in that the error by calculating the total AAL2 SSTED length and CRC. The method of claim 1, The AAL5 CPCS & SAR receiver transmits only user data after calculating the AAL2 SSTED length and CRC and the AAL5 CPCS length and CRC only for user data stored in the third memory unit when the next received cell is not the last cell. And temporarily storing user data not transmitted together with the AAL2 SSTED length, CRC, AAL5 CPCS length, and CRC in the third memory unit until the next cell arrives. . The method of claim 1, And the AAL2 CPS transmitting unit temporarily stores the remaining AAL2 CPS packet, which has not been completed as an ATM cell, in the fourth memory unit. Extracting the AAL2 CPS packet from the AAL2 ATM cell received from the lower ATM layer by the AAL2 CPS receiver and transmitting the AAL2 CPS packet to the AAL5 CPCS & SAR transmitter together with the AAL2 CPS packet UUI; Checking, by the AAL5 CPCS & SAR transmitter, whether the AAL2 CPS packet UUI included in the AAL2 CPS packet is the last part of the AAL2 SSSAR; Creating an AAL5 CPCS-PDU after calculating the final AAL2 SSTED length and CRC if it is identified as the last part of the AAL2 SSSAR; And calculating an AAL5 CPCS length and a CRC for the AAL5 CPCS-PDU to make a final ATM-SDU and transmitting it to an ATM layer. The method of claim 7, wherein Checking whether the corresponding AAL2 CPS packet can be made an ATM-SDU if it is determined that the AAL2 CPS packet UUI is not the last part of the AAL2 SSSAR; If the ATM-SDU can be made, the AAL2 CPS packet is made of the AAL5 CPCS-PDU, and the SAR process further comprises splitting the ATM-SDU into ATM-SDUs and transmitting them to the ATM layer. A5 conversion method. The method of claim 8, If the AAL2 CPS packet cannot be made into an ATM-SDU, the AAL2 SSTED length and CRC of the remaining portion of the corresponding AAL2 CPS packet and the present are calculated, and AAL5 CPCS length and CRC are calculated and stored in the second memory unit. The method according to claim 2, wherein the AI2 / AL5 conversion method further comprises a process. The method of claim 7, wherein In the process of creating the AAL5 CPCS-PDU, if the last AAL2 CPS packet is received, the AAL2 SSTED length stored in the second memory unit is added to the length of the last AAL2 CPS packet to determine whether there is an error after calculating the final AAL2 SSTED length and CRC. Making a step; Removing the AAL2 SSTED trailer from the AAL2 SSTED-PDU and attaching the AAL5 CPCS-PDU trailer to create an AAL5 CPCS-PDU. When the AAL5 ATM cell is received by the AAL5 CPCS & SAR receiver, separating user data and checking whether the cell is the last cell; Calculating the AAL2 SSTED length and the CRC when the terminal is identified as the last AAL5 ATM cell, and transmitting the same to the AAL2 CPS transmitter together with the user data; And converting the AAL2 CPS packet into an AAL2 CPS packet and transmitting the AAL2 CPS packet to a lower ATM layer. The method of claim 11, If the AAL5 ATM cell is not the last cell, storing user data in a third memory unit and waiting for the next AAL5 ATM cell to be received; When the next AAL5 ATM cell is received, determining whether the cell is the last cell; Next, when the received AAL5 ATM cell is identified as the last cell, calculating the AAL2 SSTED length and the CRC by combining the user data stored in the third memory unit and transmitting the AAL2 ATM cell to the AAL2 CPS transmitter together with the user data; And converting the AAL2 CPS packet into an AAL2 CPS packet and transmitting the AAL2 CPS packet to a lower ATM layer. The method of claim 12, If the next received AAL5 ATM cell is not the last cell, the AAL2 SSTED length and CRC are calculated only for the user data stored in the third memory unit, and only the user data is transmitted to the AAL2 CPS transmitter after calculating AAL5 CPCS length and CRC. Process of doing; The AAL2 CPS transmitter generates an AAL2 CPS packet and transmits the AAL2 CPS packet to the lower ATM layer, and transmits the AAL2 SSTED length and CRC calculated by the AAL5 CPCS & SAR receiver and the user data not transmitted together with the AAL5 CPCS length and CRC to the next AAL5 cell. And storing the third memory unit until the received data is received.