Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-04-01
2001-07-17
Jung, Min (Department: 2731)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S466000, C370S474000
Reexamination Certificate
active
06262995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an asynchronous transfer mode adaptation layer (AAL) processing apparatus and method in an asynchronous transfer mode (ATM). Particularly, this invention allows a central processing unit to process AAL
1
, AAL
3
/
4
, and AAL
5
using a software segmentation and reassembly interface device (SSID) in ATM.
2. Discussion of Related Art
In general, ATM is a transfer/exchange technique which is a core of a broadband integrated services digital network (B-ISDN), where all information is treated in units of data called cells. An ATM terminal indicates a device which performs telephone service using the ATM. It has functions such as selection, establishment, and error detection of a communication channel. The ATM cell has 53-byte length including a 5-byte central header and a 48-byte information field. This fixed length data row is utilized as a unit for multiple exchange.
There are four types such as AAL
1
, AAL
2
, AAL
3
/
4
, and AAL
5
in an ATM application layer (AAL). The AAL
1
transmits a service data unit (SDU) of a constant bit rate at the same bit rate, performs transmission of time information between information source and destination, and displays errors and error correction. The AAL
2
transmits the SDU at a variable bit rate, performs transmission of the time information between the source and destination, and displays errors and error correction. The AAL
3
and AAL
4
offer non-real time and variable bit rate services from an AAL-SAP (AAL-service access point) to an ATM-SAP, provide multiplexing service in the AAL, and have a function of transferring in connection-oriented or connectionless mode. The AAL
5
simplifies the functions and process of the AAL
3
/
4
, thus performing functions compatible with high speed data transmission.
Such a conventional ATM exchange employs a segmentation and reassembly (SAR) to allow a central processing unit to process AAL functions. As shown in
FIG. 1
, the conventional ATM exchange includes: a physical layer
1
for performing physical layer functions and supporting Universal Test and Operations Physical Interface for ATM (UTOPIA); an SAR
2
for reassembling an ATM cell outputted by the physical layer
1
to produce user data, reproducing the user data outputted by a central processing unit
5
in a form of an ATM cell through segmentation and transmitting the ATM cell to the physical layer
1
, and performing ATM and AAL functions; a local memory
3
for storing the user data and control information used when the SAR
2
performs the segmentation and reassembly; a system memory
4
for storing data and various control information for the central processing unit
5
; and the central processing unit
5
for initializing the physical layer
1
and SAR
2
and processing interrupts.
The following description is about the operation of such conventional AAL processing apparatus using the SAR in the ATM with reference to the attached drawings. An ATM cell outputted by the physical layer
1
is inputted to the SAR
2
through the UTOPIA. The SAR
2
reassembles internet protocol (IP) datagram which is fragmented at a start or central node to reconstruct the original IP datagram as user data. The central processing unit
5
then processes the user data. The SAR
2
performs the segmentation of the user data processed by the central processing unit
5
to construct an ATM cell and transmits the cell via the physical layer
1
.
In the conventional apparatus, however, the part for processing the ATM and AAL is formed in hardware, so there are problems that the hardware must be differently configured according to the types of the AAL, such as AAL
1
, AAL
2
, AAL
3
/
4
, and AAL
5
, resulting in necessity of creating new hardware design and board.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an AAL processing apparatus and method using a central processing unit in an ATM terminal that substantially obviates one or more of the limitations and disadvantages of the related art.
The present invention is aimed at overcoming the drawbacks occurring when the central processing unit processes multiple AALs in the conventional ATM terminal. An object of the present invention is to provide an AAL processing apparatus using a central processing unit in an ATM terminal, which allows transmission of ATM cells between the central processing unit and software SAR interface device (SSID) so as to process AAL
1
, AAL
3
/
4
, and AAL
5
in the ATM terminal.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, an asynchronous transfer mode adaptation layer (AAL) processing apparatus using a central processing unit in an asynchronous transfer mode (ATM) terminal includes: a physical layer for performing physical functions and supporting universal test and operations physical interface for ATM (UTOPIA); a software segmentation and reassembly interface device (SSID) for storing ATM cells outputted by the physical layer in a double port RAM under the control of a central processing unit and outputting to the physical layer the ATM cells, which have been stored in the double port RAM by the central processing unit, under the control of the central processing unit; a double port RAM for storing the ATM cells depending upon the control of the central processing unit or the SSID; a system memory for temporarily storing the ATM cells of the central processing unit; and a central processing unit, for storing in the double port RPM the user data, produced by reassembly of the ATM cells stored in the double port RAM, for storing in the double port RAM the ATM cells produced by segmentation of the user data stored in the double port RAM, and for controlling the overall system.
In another aspect, the present invention provides an AAL processing method using a central processing unit in an ATM terminal, which allows transmission of ATM cells between the central processing unit and software SAR interface device (SSID) so as to process AAL
1
, AAL
3
/
4
, and AAL
5
in the ATM terminal.
To achieve the above objective, an asynchronous transfer mode adaptation layer (AAL) processing method using a central processing unit in an asynchronous transfer mode (ATM) terminal includes the steps of: reading user data from a system memory and determining whether the user data for AAL
1
is read; segmenting the user data with the AAL
1
if the user data read is for AAL
1
; and segmenting the user data with AAL
3
/
4
or AAL
5
if the user data read is not for the AAL
1
.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5490140 (1996-02-01), Absensour et al.
patent: 5490141 (1996-02-01), Lai et al.
patent: 5537408 (1996-07-01), Branstad et al.
patent: 5717691 (1998-02-01), Dighe et al.
patent: 5751698 (1998-05-01), Cushman et al.
patent: 5867677 (1999-02-01), Tsukamoto
patent: 5999529 (1999-12-01), Bernstein et al.
patent: 6075788 (2000-06-01), Vogel
patent: 6075798 (2000-06-01), Lyons et al.
Hyundai Electronics Ind. Co. Ltd.
Jung Min
Reed Smith LLP
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