Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
2000-11-28
2003-05-13
Kizou, Hassan (Department: 2662)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S395100, C370S395430, C370S401000, C370S467000
Reexamination Certificate
active
06563816
ABSTRACT:
BACKGROUND OF THE INVENTION
The public switched telephone network (PSTN) based on circuit switching technology has served well for the past several decades in making a broad range of telephony services possible for consumers and businesses. However, its infrastructure is fraught with cost inefficiencies, inflexible service creation and delivery platforms, and manually-intensive, error-prone operations, administration and maintenance (OA&M) applications and processes. All of these aspects combine to keep prices artificially high and make service creation and delivery intervals unduly long from an end-user perspective. In contrast, the broadband networking platforms that are being deployed for data services are optimized for high efficiencies and fast service creation due to the speed at which the market is driving the growth of new services. Given the large-scale investments in broadband network technologies being undertaken by the service providers to meet the explosive growth in demand, planning is underway to migrate voice services from the legacy circuit-switched environment to the newer broadband networking environment to take advantage of economies of scale. However, this migration needs to be carefully planned so it does not create a significant discontinuity in the features, services, and overall quality that customers have come to expect from the well-established circuit-switched network.
In the past, the typical home had a single telephone line for all the residents to share. Today, there has been a dramatic increase in the need for communication services in the home driven by such factors as telecommuting, home offices, residential facsimile machines and computer networking including Internet access.
In the traditional PSTN environment, each telephone circuit, called a “loop”, requires a separate wire pair from the access service provider's facilities to the subscriber's location. This places practical limits on the number of circuits that may be available at each subscriber location, especially for residential subscribers. The access service provider generally does not have sufficient capacity in the loop facilities to provide multiple telephone lines to every subscriber.
Furthermore, most homes have been wired for one or at most two telephone lines. Adding a new telephone line beyond this usually requires adding new wiring in the home. This home wiring limit acts as a barrier to residential users who may want additional telephone lines and to service providers who would like to gain additional revenues from providing new communication services.
SUMMARY OF THE INVENTION
It is desirable to provide a migration strategy that uses the broadband network for multiplexing efficiencies (which leads to significantly lower unit costs) and logical provisioning benefits (which leads to significant reduction in service turn-up times) while continuing to leverage the PSTN's switching and service control engines (Class 4/5 switches, SCPs, etc.) for providing value-added services. This low-risk migration can be achieved by using a gateway between the broadband network and the PSTN.
It is desirable to provide a capability that could enable greater communication services in the home without adding wiring in the home or to the service provider's facilities.
The present invention provides a gateway between the broadband network and the PSTN while also providing distribution of multiple voice lines over a home local area network.
In accordance with the present invention, a loop carrier system includes a home local area network having plural telephone modules and a hub coupled to a communications medium. The communications medium in a preferred embodiment comprises in-home telephone wiring, though other communications media are possible, including wireless. The telephone modules and the hub communicate digitized voice signals over the in-home wiring in a dedicated frequency band located above the traditional baseband services, e.g., plain old telephone service (POTS). The hub converts between voice signals and voice packets and is connected to a network access device for transferring the voice packets from the home local area network to a telecommunications network which routes the voice packets to a gateway. The gateway converts between the voice packets and a circuit format compatible with a local digital voice switch. The voice packets can be any packet format such as ATM cells (e.g., ATM Adaptation Layer versions AAL1, AAL2, AAL5) or IP packets. The network access device can be, for example, an xDSL device, a cable modem or wireless access device.
According to an aspect of an embodiment of the system, the hub includes a data interface circuit for converting between data signals and data packets and a packet multiplexer for multiplexing data packets with voice and signaling packets for transfer between the hub and the gateway.
In an embodiment, the gateway comprises an ATM switch and a call processing adjunct which controls the conversion between voice packets and the circuit format at the ATM switch. The call processing adjunct communicates with the hub and with the local digital switch using signaling protocols (e.g., Media Gateway Control Protocol and GR-303, respectively) for controlling call processing in the loop carrier system.
According to an aspect of the invention, a network element includes a Common Object Request Broker Architecture (CORBA)-based server, CORBA-based managed objects accessible by the CORBA-based server and a CORBA-based applications programming interface (API). The CORBA-based API is coupled to an external operations support system which can manage the plural CORBA-based managed objects directly.
According to an aspect of the home local area network, a communication protocol is used between the hub and the telephone modules in which the voice signals are transmitted within frames of digital bits from the hub to the modules in the downstream direction and from the modules to the hub in the upstream direction using time division duplex transmission. The downstream and upstream frames include communication timeslots assigned to individual modules for communication between the modules and the hub. The timeslots are assigned such that no two modules have the same timeslot, thereby avoiding collision on the in-home wiring.
According to another aspect of the home local area network, the digital bits are transmitted using a raised cosine pulse signal modulated by a carrier signal at the center of the dedicated frequency band.
In accordance with the invention, a telephone module for communicating between a local hub and a telephone set over telephone wiring includes a digitizer for converting analog voice signals from the telephone set to digital signals at a baseband frequency and a modulator for modulating a carrier signal with the digital signals for transmission in a dedicated frequency band above baseband over the telephone wiring to the local hub.
According to another aspect of the home local area network, a timing recovery mechanism in the absence of a clock that is traceable to the Primary Reference Clock on the public network is robust to clock drift, cell delay variation and cell impairments.
According to another aspect of the invention, a method of configuring a selected ATM endpoint connected to a server across an ATM network for Internet Protocol (IP) over ATM communications comprises transmitting an unsolicited message from the server to the selected ATM endpoint. The message is send at a first transmission interval over an associated virtual circuit and includes a server IP address and an ATM endpoint IP address. At the ATM endpoint, the unsolicited message is received, the server IP address and the ATM endpoint IP address are extracted from the unsolicited message, and an SNMP TRAP message is sent to the server.
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patent: 5742596 (1998-04-01), Bar
Monteiro Anthony
Nodoushani Paiman
Cisco Technology Inc.
Elallam Ahmed
Hamilton Brook Smith & Reynolds P.C.
Kizou Hassan
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