Multiplex communications – Channel assignment techniques
Reexamination Certificate
1997-03-27
2001-09-04
Kizou, Hassan (Department: 2662)
Multiplex communications
Channel assignment techniques
C370S352000, C370S401000, C379S093050, C379S093320, C710S120000
Reexamination Certificate
active
06285680
ABSTRACT:
COPYRIGHT NOTICE
Copyright, 1995, 1996, 1997, Microcom Systems, Inc. A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
REFERENCE TO APPENDIX
This application includes Appendix A comprising 392 pages.
1. Field of the Invention
This invention relates to central site telecommunications systems and more particularly, to a device capable of processing and routing calls originating from both digital and analog networks to create connections with selected LAN and WAN resources.
2. Background of the Invention
With the growth of data communications today, organizations are finding that they are having to support a broad range of remote access and wide area network (WAN) services. For example, a typical corporate network can provide one WAN service connection for satellite offices to provide local area network (LAN) connectivity, another service connection for remote users such as a mobile sales force, yet another for telecommuters and still another for customers. Typically, each of these service connections supports only one type of WAN technology, such as the Public Switched Telephone Network (PSTN) or the Integrated Services Digital Network (ISDN). In addition each different type of service connection requires a separate piece of hardware at the corporate site to support the connection. Thus, the corporate network administrator must manage several different WAN connections and services.
With the growth of the Internet, the local telephone companies and Internet service providers (ISPs) are finding that their WAN connection services are being utilized to capacity. Typically, these organizations provide a separate telephone number for each of the services they provide. Thus, depending upon the type of connection required by the remote user, the remote user will be given a telephone number dedicated to providing a specific service. In the case of a local telephone company or other provider of virtual private network services, each user or group of users is assigned to a dedicated telephone number in order to control access. As a result, the telephone companies are running out of telephone numbers and service capacity.
The most common WAN services include the PSTN, ISDN and T
1
services. Each of these services permits the transfer of digital data between a remote system and a host system, however, the benefits and disadvantages of each of these types WAN services are different, such that an organization's selection of WAN services will vary depending upon the organization's requirements.
The PSTN is a network designed primarily for the transmission of voice information an d the subscriber accesses the network through an analog network connection. One the benefits of the PSTN is that it provides the broadest area of access at a relatively low price. Through the use of modems, these networks are capable of transmitting data, although even using the state of the art technology the data bandwidth is very limited. In order to meet the demand for increased bandwidth, other services such as integrated services digital network (ISDN) and T
1
are now being offered.
T
1
service is a digital network service designed to allow higher speed data communication for commercial users and c an provide data rates up to 1.544 Mbps. T
1
is also available as a channelized service which allows for multiple data connections over a single physical connection, thus permitting more efficient use of existing hardware. Channelized T
1
(herein referred to as T
1
) service provides up to 24 separate data connections over a single physical connection. T
1
service is not available in all areas and is generally limited to commercial users and thus not available to residential users such a telecommuters and segments of the consumer market.
The ISDN is a switched digital network that enables the local telephone company to provide a range of services in order to meet the needs of their users and enable the telephone company to utilize their resources (circuits and switches) efficiently. A switched network is a network that provides a choice of services for establishing a circuit or network connection between parties. Those services typically include circuit switching services and packet switching services; however, other services such as asynchronous transfer mode (ATM) or frame relay technology are also available in some areas. The ISDN can provide the available services to the user on an as needed basis as well as enables the user to increase or decrease bandwidth on demand. ISDN service is not available in all areas and the costs in some areas make the benefit of ISDN 's increased data rate only economical to users with very high bandwidth requirements.
ISDN service usually comprises one D-channel and one or more B-channels. The D-channel is used to setup the call with the ISDN service provider central office and to provide all the call control signals for each of the B-channels. The user contacts the telephone company via the D-channel in order to establish a connection with a remote user across the network as well as request different types of services provided by the network. Typically, the D-channel data rate can be 16K or 64K bits per second (bps). The B-channel or Bearer Channel is the basic user channel for the transfer of information and can provide a data rate of up to 64K bits per second (bps) per channel. It can be used to carry digital data, analog signals in the form of digitized voice, or a combination of the two. More than one B-channel can be combined to achieve higher data rates. Essentially, three kinds of circuit or network connections can be setup over a B-channel: circuit switched, packet switched and semipermanent (equivalent to a leased line). In addition to or instead of B-channels, H-channels, providing data rates greater than 64 Kbps, can be provided.
Basic ISDN access service, intended for residential and small office subscribers, is provided by what is called a Basic Rate Interface (BRI) which typically consists of two B-channels and one D-channel. A Primary Rate Interface (PRI), intended for commercial subscribers, typically consists of 23 or 30 B-channels and one D-channel. The PRI may also include H-channels instead of or in addition to B-channels.
Currently, the PSTN, T
1
and the ISDN services coexist in the market place. The majority of local telephone companies can provide subscribers with access to either service in order to meet the subscriber's needs. These local telephone companies also provide an interface between the PSTN, the ISDN or the T
1
networks in order to permit subscribers connected to one network to establish connections with subscribers on the other network. Without such an interface, subscribers connected to the ISDN, for example, would not be able to call subscribers connected to the PSTN and vice versa.
This PSTN-ISDN/T
1
interface includes the equipment necessary to convert the PSTN signal to an ISDN or T
1
compatible signal and vice versa. Typically, data transferred on an analog network is transmitted in the form of modulated analog signals. Common industry standard modulation schemes are described in ITU-T V0.32 and V0.34 Recommendations. At the interface between the digital and analog networks, the modulated analog signals are converted to a Pulse Coded Modulation (PCM) digital data stream for transmission across the digital network and the PCM digital data stream is converted to a modulated analog signal for transmission across the analog network.
ISDN service use s the D-channel to notify a party of an incoming call. One of the features available with ISDN service is that a party receiving an incoming call can re
Meaney Edward J.
Steinka Bradford R.
Kizou Hassan
Microcom Systems, Inc.
Mintz Levin Cohn Ferris Glovsky and Popeo P.C.
Pezzlo John
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