Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
2000-07-26
2004-04-13
Duong, Frank (Department: 2666)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S355000, C370S356000
Reexamination Certificate
active
06721307
ABSTRACT:
CLAIM OF PRIORITY
This application claims priority and all benefits accruing under 35 U.S.C. Section 119 to an application entitled “Device for Processing Voice and Facsimile Data in Remote Access Server” filed in the Korean Industrial Property Office on Aug. 28, 1999 and there duly assigned Serial No. 99-36160.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a communication system. More particularly, the present invention relates to a remote access server (RAS) for remotely processing voice and data information.
2. Description of the Related Art
FIG. 1
illustrates a network linked to a remote access server which supports the processing of voice and data information over the Internet. Remote users can dial into the remote access server over the public switched telephone network to get direct links to the Internet from a remote site, just as if they were connected locally. As shown in
FIG. 1
, the remote access servers
2
and
20
are coupled to different network types to provide Internet users with more economical services for the conventional long-distance call services, the facsimile transmission services, and other additional services. The remote access servers
2
and
20
are connected to the Private Automatic Branch Exchanges (PABXs)
4
and
22
, the Public Switched Telephone Network/Integrated Service Digital Network (PSTN/ISDN)
6
, the PSTN
24
, and the routers
8
and
26
, respectively. The respective routers are connected to the Internet
18
via the Ethernet connection. The PABX
4
is connected to the facsimile (FAX)
10
, the telephone
12
, and the PSTN/ISDN
6
, and the PABX
22
is connected to the PSTN
24
. The router
8
is connected to a server
14
, a personal computer (PC)
16
, and the router
26
is connected to a server
30
and a PC
28
. The router
8
is connected to the router
26
via the Internet
18
. The remote access servers
2
and
20
transmit voice and facsimile data from a public network, such as the PSTN/ISDN
6
and the PSTN
24
, to another public network.
FIG. 2
depicts a module for processing voice and data information of the remote access servers
2
and
20
as illustrated in FIG.
1
. As shown in
FIG. 2
, the module includes a system main controller interface
34
connected to a system main controller
32
; a Main Processing Unit (MPU)
36
; four voice/facsimile codecs
38
; a memory
40
, Ethernet
42
; a decoder
44
; a glue logic
46
; and, a PCM (Pulse Code Modulation) interface
48
connected to an El trunk interface
50
. The system main controller interface
34
exchanges the operating state, the access information of the voice/data processing module, and the system configuration information. The system main controller
34
also downloads a software application for the system operation. The memory
40
is comprised of a flash memory for storing programs, a DRAM (Dynamic Random Access Memory), and an SRAM (Static Random Access Memory). The Ethernet
42
processes an Ethernet protocol and enables access to an IP (Internet Protocol) network using 10-base T. The decoder
44
and the glue logic
46
perform address decoding to enable the MPU
36
to control each peripheral part thereof. The PCM interface
48
exchanges voice data through a time switch of the system and a PCM highway to provide voice signal to the voice/facsimile codecs
38
.
In the module as shown in
FIG. 2
, a single MPU
36
performs the protocol operation for the voice and data processing function in a local area network (LAN), the signaling processing function with the PSTN, and the IPC (Inter-Processor Communication) processing function with the system main controller
32
. The MPU
36
has a processing capability of 4.5 MIPs (Million Instructions Per second) with the system clock of 25 MHz. Although such a module is implemented to process voice and facsimile data of approximately 16 channels, it experiences problems in processing all 16 channels. The factors to be considered to determine the capability of codecs
38
to process all 16 channels depends on the design specification and its required processing time of the codecs, as set forth under the ITU (International Telecommunications Union-Telecommunications standard sector) Recommendations—G.723.1 (6.3 Kbps), G726 (32 Kbps) and G.729 (8 Kbps). That is, for enabling the four voice/facsimile codecs
38
to process 16 channels, the required time to process one channel is 30 ms for G.723.1 codec and 0.75 ms for G.711 codec. The interrupt processing time of the voice/facsimile codes is 30 ms and the protocol processing time is 10 ms. However, if these conditions are not met, undue delays may occur in the performance of the server limited by its processing ability, thus degrading the voice quality. As the voice data transmission is very sensitive to the delay, the MPU must perform without adding undue delays as it forwards data packets.
Generally, a network delay is divided into a transmission delay and a processing delay. When the sum of the transmission delay and the processing delay is in the range of about 150-200 ms, most users will be able to enjoy data and voice service over the Internet.
Currently, the conventional voice/facsimile codecs
38
, as depicted in
FIG. 2
can not process all 16 channels (64 Kbps per channel) due to its limited processing capability of approximately 4.5 MIPs. It also processes the interrupt service routine for encoding the voice and facsimile data received from the E1 trunk interface
50
and the PCM interface
48
. As a result, the conventional module is limited to perform voice and facsimile data only up to 8 channels.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a device capable of servicing a maximum number of subscriber ports in a network system and to provide a voice and facsimile subscriber module for a remote access server to efficiently operate the system.
To achieve the above object, there is provided a device for processing voice and data in a remote access server which provides a voice and facsimile data transmission service over the Internet. The device includes a first interface for interfacing with a public network; a second interface for interfacing with the Internet; and a remote access server coupled to the first and the second interfaces for transmitting voice and facsimile data received from the first interface to the Internet via the second interface, and for transmitting voice and facsimile data received from the second interface to the public network via the first interface. The remote access server includes a plurality of voice/facsimile codecs, each having a plurality of channels connected to the first interface for encoding and decoding voice and facsimile data provided from the first interface and the second interface; a codec controller for controlling the associated voice/facsimile codecs and for controlling the generation of an interrupt in the corresponding voice/facsimile codec in response to a specific protocol information to process the voice and facsimile data received through the channels; a slave processor for providing the voice and facsimile data to one of the specified channels for outputting the voice and facsimile data encoded by voice/facsimile codecs upon receipt of the interrupt, and for decoding the voice and facsimile data provided from the second interface and outputting the decoded voice and facsimile data to the first interface; and, a master processor for communicating with a system operator and for managing the slave processor.
REFERENCES:
patent: 5577105 (1996-11-01), Baum et al.
patent: 5742596 (1998-04-01), Baratz et al.
patent: 5892764 (1999-04-01), Riemann et al.
patent: 5912888 (1999-06-01), Walsh et al.
Cha & Reiter L.L.C.
Duong Frank
Jagannathan Melanie
Samsung Electronics Co,. Ltd.
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