KR20030052820A - Apparatus for ATM Adaptation Layer Type conversion of wireless communication base station - Google Patents

Abstract

PURPOSE: An AAL type conversion device in a wireless communication base station is provided to install an AAL type converter in a base station, and to simultaneously receive many channels having optional VPIs/VCIs, thereby efficiently using T1/E1 links and enabling channel expansion by expanding a CAM(Content Addressable Memory) and a DPRAM. CONSTITUTION: A CAM(35) is mapped with header information of an ATM cell, and outputs new header information. A type confirmer(31) determines whether to type-convert or bypass the inputted ATM cell. An AAL5/2 converter(32) converts a determined AAL5-type ATM cell into an AAL2-type ATM cell. A DPRAM(36) stores a packet if the AAL5-type ATM cell is not assembled to the AAL2-type ATM cell. A bypass unit(33) stores at least one ATM cell to be bypassed. A cell multiplexer(34) selectively outputs the ATM cell stored in the AAL5/2 converter(32) and the bypass unit(33).

Description

Apparatus for ATM Adaptation Layer Type conversion of wireless communication base station

The present invention relates to an AAL (ATM: ATM Adaptation Layer) type conversion apparatus in a wireless communication base station, and more particularly, a base station (Node-B) and a control station (RNC) used in a next generation mobile communication system. The present invention relates to an AAL type conversion apparatus of a base station for efficient use of a link between

1 is a diagram illustrating a configuration of a general wireless communication base station, and shows a structure of a base station Node-B that receives and processes radio signals from a plurality of mobile stations (UEs).

Conventionally, a radio signal from a plurality of mobile stations (UE) 10 is received by a radio unit 21 of a base station (Node-B) 20, and the AAL type conversion unit 22 converts the radio signal into an ATM signal. The ATM signal is converted into a signal corresponding to T1 / E1 for transmission by the line interface unit 23 to the T1 / E1 link connected to the control station RNC. At this time, when a single user's data is transmitted on the T1 / E1 link much smaller than the payload in the ATM cell, a large amount of free space occurs in the AAL5 type ATM cell.

In order to prevent such a large amount of free space from occurring, an ATM cell type has been proposed that can aggregate data transmitted from a plurality of users and have different destinations, and this type is referred to as an "AAL2 type ATM cell". It is defined by International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Recommendation I.363.2.

As described above, the AAL type conversion unit 22 is designed for efficient use of the link.

The AAL type converter 22 functions to convert an AAL5 type ATM cell containing a small amount of data into an AAL2 type. The AAL2 type ATM cell structure is illustrated in FIG. 2A, and a process of converting an AAL5 type ATM cell to the AAL2 type is illustrated in FIG. 2B.

As shown in FIG. 2A, an AAL2 type ATM cell has a structure including a plurality of such short cells using a cell having a small amount of data as a short cell.

The start field (STF) includes a 6-bit offset field (OSF), a 1-bit sequence number (SN), and a 1-bit P (odd parity of STF). In Fig. 2A, each number in parentheses represents the number of bits of the corresponding data.

As shown in FIG. 2B, the AAL5 type ATM cells (A, B, and C) having a small amount of data are converted into an AAL2 type ATM cell of one AAL2 type and transmitted over a T1 / E1 link, thereby efficiently linking. Can be used as

In addition, the base station (Node-B) 20 having a device functioning as described above should be easy to expand the system according to the increase in the number of subscribers.

Accordingly, the Node-B 20 converts the input AAL5 type ATM cell into an AAL2 type ATM cell for the efficiency of the T1 / E1 link and efficiently copes with the system expansion according to the increase in subscribers. This is required.

The present invention has been proposed to meet the above requirements, and converts an AAL5 type ATM cell input in a wireless communication system into an AAL2 type ATM cell for the efficiency of a T1 / E1 link, and also increases the number of subscribers. It is an object of the present invention to provide an AAL type conversion apparatus in a base station for efficiently coping with system expansion.

1 is an exemplary configuration diagram of a general wireless communication base station.

2A is an explanatory diagram showing a typical AAL2 type ATM cell structure.

2B is an explanatory diagram showing a process of converting a general AAL5 type ATM cell into an AAL2 type;

3 is a block diagram of an embodiment of an AAL type conversion apparatus in a wireless communication base station according to the present invention;

4 is a detailed configuration diagram of an embodiment of the type checking unit of FIG. 3 in accordance with the present invention.

5 is a detailed configuration diagram of an embodiment of the AAL5 / 2 conversion unit of FIG. 3 according to the present invention;

6 is a detailed flowchart illustrating a process of interfacing with DPRAM in the DPRAM interface unit of FIG. 5 according to the present invention;

* Explanation of symbols for the main parts of the drawings

31: type checking unit 32: AAL5 / 2 conversion unit

33: bypass unit 34: cell multiplexing unit

35: Content Addressing Memory (CAM) 36: Dual Port RAM (DPRAM)

The present invention for achieving the above object, in the AAL (ATM: ATM Adaptation Layer) type conversion apparatus in a wireless communication base station, outputs the new header information by mapping with the header information of the input asynchronous transfer mode (ATM) cell First storage means; Type checking means for determining whether to typecast or bypass the input ATM cell based on the first storage means; AAL5 / 2 converting means for converting an AAL5 type ATM cell to be converted by the type checking means into an AAL2 type ATM cell; Second storage means for storing a packet in a corresponding area when the AAL5 type ATM cell to be type-converted cannot be assembled into an AAL2 type ATM cell; storing at least one ATM cell to be bypassed determined by the type checking means; Bypass means for; And cell multiplexing means for selectively outputting the ATM cells stored in the AAL5 / 2 conversion means and the bypass means according to a control signal.

The present invention relates to an AAL type conversion technology for efficient use of a link between a wireless communication base station and a control station. The present invention relates to a content addressable memory (CAM) that stores conversion information of an input ATM cell. AAL5 / 2 conversion that functions to convert AAL types while interfacing with Dual Port Random Access Memory (DPRAM) that stores packets of channels, and Content Addressing Memory (CAM) and Dual Port Memory (DPRAM). It consists of wealth.

In the present invention, the content addressing memory (CAM) and the dual port memory (DPRAM) are appropriately used, and the content addressing memory (CAM) is a virtual path identifier (VPI) / virtual channel of an input AAL5 type ATM cell. Based on the VCI (Virtual Channel Identifier), it saves the information for changing to AAL2 type cell, and the dual port RAM (DPRAM) stores the packet of the channel during AAL2 conversion and can be completed as one ATM cell. Function to output In addition, the AAL5 / 2 converting unit, which controls while interfacing with the content addressable memory (CAM) and the dual port RAM (DPRAM), may be implemented as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). System expansion by increasing the number of channels is possible only by expansion of dual port RAM (DPRAM) and content addressable memory (CAM) without modification to AAL type conversion unit.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of an embodiment of an AAL type conversion device at the end of a wireless communication base station according to the present invention.

As shown in FIG. 3, the AAL type conversion device according to the present invention includes a content addressing memory (CAM) 35 which maps with header information of an input asynchronous transfer mode (ATM) cell and outputs new header information. Based on the content addressing memory (CAM) 35, the type checking unit 31 and the type checking unit 31 determine whether to type convert or bypass the input ATM cell. An AAL5 / 2 conversion unit 32 for converting an AAL5 type ATM cell to type conversion into an AAL2 type ATM cell, and an AAL5 type ATM cell to which the AAL5 type ATM cell cannot be assembled into an AAL2 type ATM cell are used. Dual port RAM (DPRAM) 36 for storing the data, a bypass unit 33 for storing at least one ATM cell to bypass determined by the type checking unit 31, and an AAL5 / 2 conversion unit 32. ) And the ATM cell stored in the bypass section 33 according to the control signal. And a cell multiplexing unit (34) for output to the enemy.

In particular, the content addressing memory (CAM) 35 stores information for changing to an AAL2 type ATM cell based on a virtual path identifier (VPI) / virtual channel identifier (VCI) of an AAL5 type ATM cell to be input. In case of AAL2 type ATM cell conversion, the dual port RAM (DPRAM) 36 stores the packet of the corresponding channel and outputs it if it can be completed as one ATM cell.

The type checking unit 31 performs a function of determining whether to type-convert or bypass the input ATM cell.

The AAL5 / 2 conversion unit 32 receives an AAL5 type ATM cell as an input and performs a function of converting the AAL5 into AAL2 while interfacing with the dual port RAM (DPRAM) 36. The AAL5 / 2 conversion unit 32 may be made using an FPGA or an on-demand semiconductor. .

The bypass unit 33 stores a cell in order to bypass the input ATM cell. It consists of FIFO (first-in-first-out) memory and performs the function of outputting the ATM cell stored by the control signal.

The cell multiplexer 34 selectively outputs the ATM cells stored in the AAL5 / 2 converter 32 and the bypass unit 33.

The content addressing memory (CAM) 35 performs a function of outputting new header information by mapping with header information of an input ATM cell.

The dual port RAM 36 stores a packet in a corresponding area when an ATM cell inputted for type conversion cannot be assembled into an AAL2 type cell. Each channel is allocated to the dual port RAM (DPRAM) 36. If the 48 bytes can be completed by combining the input packet and the stored packet, the output packet is output if the 48 bytes cannot be made. Save it to

4 is a detailed configuration diagram of an embodiment of the type verification unit of FIG. 3 according to the present invention, in which “41” represents a CAM interface unit and “42” represents an ATM cell demultiplexer, respectively.

Since the AAL5 type ATM cell to be input may be a traffic cell having user information or a control cell for control, the CAM interface unit 41 selects the VPI / VCI in the ATM cell header for the traffic cell and the control cell. It classifies based on the information and outputs the information mapped to the content addressing memory (CAM).

The ATM cell demultiplexer 42 converts the ATM cell to be bypassed into the bypass unit 33 according to the information obtained from the content addressing memory (CAM) 35, and the ATM cell to be converted is the AAL5 / 2 conversion unit 32. ) To send to.

FIG. 5 is a detailed configuration diagram of an AAL5 / 2 converter of FIG. 3 according to an embodiment of the present invention, in which "51" is a header / packet separating unit, "52" is an information storing unit, and "53" is a packet storing unit. "54" denotes a DPRAM interface portion and "55" denotes a first-in first-out (FIFO) portion, respectively.

The header / packet separating unit 51 separates the header and the packet of the input ATM cell to separate the AAL5 packet part included in one ATM cell. Packets separated in this manner are input to the packet storage 53, and packet length information and information to be converted are input to the information storage 52.

The packet storing unit 53 stores only packets in an AAL5 type ATM cell, and outputs packets according to a control signal of the DPRAM interface unit 54.

The information storage unit 52 stores the AAL5 length required for the type conversion, the corresponding DPRAM address of the input cell, the stored DPRAM packet length information, and the like, and outputs information according to the control signal of the DPRAM interface unit 44. Perform.

The DPRAM interface unit 54 receives the VPI / VCI information to be converted, the AAL5 packet length, the address to be input to the dual port RAM (DPRAM) 36, and the DPRAM packet length information, and if possible, can be assembled into an AAL2 type ATM cell. The packets which are stored in the electoral (FIFO) unit 55 and whose cell assembly is not completed are stored in the dual port RAM (DPRAM) 36 according to the address to be input to the dual port RAM (DPRAM) 36.

The first-in first-out (FIFO) unit 55 is a memory for storing type-converted ATM cells, and performs a function of outputting an ATM cell to the cell multiplexer 34. That is, the cell multiplexer 34 stores the converted ATM cell until the ATM cell can receive the ATM cell.

6 is a detailed flowchart illustrating a process of interfacing with DPRAM in the DPRAM interface unit of FIG. 5 according to the present invention.

When the cell is in the cell processing state (601), the DPRAM interface unit 54 receives the VPI / VCI, the AAL5 length to be converted by the information storage unit 52, the corresponding DPRAM address of the input cell, and the stored DPRAM packet length information (602). ).

At this time, if the input cell AAL5 packet length and the DPRAM packet length exceeds 48 bytes (603), the AAL2 type ATM cell is assembled and outputted. At this time, an ATM header is generated and output according to the input VPI / VCI information. In operation 605, 48 bytes obtained by adding the DPRAM packet and the AAL5 packet are output (606). Subsequently, the STF is generated according to the length of the remaining AAL5 packet and stored in the dual port RAM (DPRAM) 36 (607). The DPRAM packet length is modified to 1 byte of STF length, and the AAL5 packet length is output and remaining. The AAL5 packet length is modified (608).

When the above process is completed, the process transitions to step 603 to check whether the sum of the DPRAM packet length and the AAL5 packet length is 48 bytes or more. If the sum of the DPRAM packet length and the AAL5 packet length does not exceed 48 bytes, it is stored in the corresponding area of the dual port RAM (DPRAM) 36 (604) and waits for the next cell.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention includes an AAL type conversion unit in a base station, which accommodates a plurality of channels having arbitrary VPI / VCI and enables efficient use of a T1 / E1 link, and replaces an existing circuit when a channel is expanded. The channel can be expanded by only expanding CAM and DPRAM without the need, thereby providing a flexible system.

Claims (9)

In the AAL (ATM: ATM Adaptation Layer) type conversion apparatus in a wireless communication base station, First storage means for outputting new header information by mapping with header information of an input asynchronous transfer mode (ATM) cell; Type checking means for determining whether to typecast or bypass the input ATM cell based on the first storage means; AAL5 / 2 converting means for converting an AAL5 type ATM cell to be converted by the type checking means into an AAL2 type ATM cell; Second storage means for storing a packet in a corresponding area when the AAL5 type ATM cell to be type-converted cannot be assembled into an AAL2 type ATM cell; Bypass means for storing at least one ATM cell to bypass determined by said type checking means; And Cell multiplexing means for selectively outputting the ATM cells stored in the AAL5 / 2 conversion means and the bypass means according to a control signal ALA-type conversion device in a wireless communication base station comprising a. The method of claim 1, The first storage means, ALA type conversion device in a wireless communication base station storing information for changing to an AAL2 type ATM cell based on a virtual path identifier (VPI) / virtual channel identifier (VCI) of an input AAL5 type ATM cell . The method of claim 1, The second storage means, When converting AAL2 type ATM cell, it saves the packet of the channel and outputs it if it can be completed as one ATM cell, but is allocated for each channel, and if the input packet and the stored packet can be combined to complete 48 bytes And outputting and storing an input packet in a corresponding memory area if 48 bytes cannot be generated. The method of claim 1, The bypass means, And an FIFO (first-in first-out) memory for outputting an ATM cell stored by the control signal. The method according to any one of claims 1 to 4, The type checking means, The AAL5 type ATM cell to be input may be a traffic cell having user information or a control cell for control. Therefore, the traffic cell and the control cell are classified based on the VPI / VCI in the ATM cell header. A CAM interface unit configured to output information mapped with the first storage unit (CAM); And An ATM cell demultiplexer for transmitting an ATM cell to be bypassed to the bypass means according to the information obtained from the first storage means CAM, and an ATM cell to be converted to the AAL5 / 2 conversion means; ALA-type conversion device in a wireless communication base station comprising a. The method of claim 5, The AAL5 / 2 conversion means, Header / packet separating means for separating a header and a packet of an input AAL5 type ATM cell; A packet storage unit for storing AAL5 packets of ATM cells separated by the header / packet separating means and outputting AAL5 packets according to a control signal; A header information storage unit for storing header information separated by the header / packet separating means and outputting the header information according to the control signal; The control signal is generated, and with reference to the header information, if an AAL5 type ATM cell can be assembled into an AAL2 type ATM cell, the AAL5 type ATM cell is assembled into an AAL2 type ATM cell and stored in a first-in first-out (FIFO) unit. A DPRAM interface unit for storing AAL5 packets in which cell assembly is not completed in the second storage unit (DPRAM); And The first in, first out (FIFO) unit for storing at least one type-converted ATM cell ALA-type conversion device in a wireless communication base station comprising a. The method of claim 6, The header information is Substantially, an ALA-type conversion device in a wireless communication base station comprising VPI / VCI information to be converted, AAL5 packet length information, address information to be input to DPRAM, and DPRAM packet length information. The method of claim 6, AAL5 / 2 conversion process in the DPRAM interface unit, A first step of receiving a VPI / VCI to be converted in the header information storage unit, an AAL5 length, a corresponding DPRAM address of an input cell, and stored DPRAM packet length information in the header information storage unit; A second step of comparing whether an input cell AAL5 packet length and a DPRAM packet length are 48 bytes or more; A third step of assembling and outputting the AAL2 type ATM cell if the cell AAL5 packet length and the DPRAM packet length are 48 bytes or more as a result of the comparison of the second step; A fourth step of generating and outputting an ATM header according to the VPI / VCI information input in the third step, and outputting 48 bytes obtained by adding a DPRAM packet and an AAL5 packet; And A STF (Start Field) is generated according to the length of the remaining AAL5 packet output in the fourth step, and stored in the second storage means (DPRAM), the DPRAM packet length is modified to 1 byte of STF length, and the AAL5 packet length is generated. A fifth step of outputting the AAL5 packet length and modifying the remaining AAL5 packet length to the second step ALA-type conversion device in a wireless communication base station comprising a. The method of claim 8, As a result of the comparison of the second step, if the sum of the length of the DPRAM packet and the length of the AAL5 packet does not exceed 48 bytes, the sixth step of storing in the corresponding area of the second storage means DPRAM by the inputted information and waiting for the next cell. ALA-type conversion device in a wireless communication base station further comprising.