MXPA00009327A - A system to provide lifeline ip telephony service on cable access networks - Google Patents

Abstract

A cable access network includes a cable trunk amplifier connected over a coaxial cable to A plurality of cable data modems to provide backup power to the cable modem during power outages experienced by either the trunk amplifier or the modems, thereby insuring uninterruptible IP telephone service. The trunk amplifier applies a DC voltage across the conductors of the coaxial cable. An AC/DC power converter and regulator and also a backup battery are sources of power for the DC voltage applied to the coaxial cable. A power outage sensor selectively connects either the AC/DC power converter and regulator or, alternately, the backup battery to the cable, depending on whether there is an outage sensed at the trunk amplifier. Each cable data modem connected to the trunk amplifier is partitioned into IP voice circuits and other circuits not contributing to the IP voice function. The other circuits include, for example, video/audio receiver circuits and IP data transceiver circuits. The IP voice circuits are connected to the subscriber's telephone hand set. The cable data modem applies a DC voltage to the IP voice circuits and the subscriber's telephone hand set. An AC/DC power converter and regulator in the modem and also the DC voltage from the coaxial cable are sources of power for the DC voltage applied to the IP voice circuits. A power outage sensor selectively connects the IP voice circuits to either the AC/DC power converter and regulator in the modem or, alternately, the DC voltage from the coaxial cable, depending on whether there is an outage sensed at the cable data modem. The other circuits such as the video/audio receiver circuits and IP data transceiver circuits are powered only by the AC/DC power converter and regulator in the cable data modem. In this manner, if there is a general power outage affecting both the trunk amplifier and many of the cable data modems connected to it, the power to be supplied by the backup battery at the trunk amplifier is only required to power the IP voice circuits and the subscriber's telephone hand set.

Description

SYSTEM TO PROVIDE SECURE LINE IP TELEPHONY SERVICE IN CABLE ACCESS NETWORKS BACKGROUND OF THE INVENTION The invention described is broadly related to telecommunications and relates more particularly to systems and methods for providing telephony for cable access networks.

Broadband access networks (for example, fiber / coaxial hybrid) are used to provide television programming and Internet access for customers. Very recently they have been investigated to provide IP telephony service. However, the reliability of the fiber / coaxial hybrid (HFC) cable networks does not compare with the high reliability of the local telephone network. Local telephony networks are designed to meet an unavailability target of 53 minutes / year / line. HFC cable networks have a timeout of 622 minutes / year / line due to AC power failures (alternating current) and 125 additional minutes / year / line due to failures other than AC power failures (eg, amplifier failures, water infiltration, REF .: 121799 wire cut). A key difference between a local cycle network and an HFC cable network is that the former uses battery power in the central office. The latter requires commercial AC power in the field for amplifiers and coaxial connections and at subscriber locations for cable modem and telephone sets. The AC power losses cause a failure in the supply of the HFC cable network and in the subscriber's modem and telephone.

What is required is an effective cost criterion to provide an uninterrupted telephone service in an HFC cable network in the face of power outages anywhere from the main terminal of the cable network to the subscriber's telephone.

BRIEF DESCRIPTION OF THE INVENTION A communications network topology that provides uninterruptible telephone services in cable access networks is described. A hybrid fiber / coaxial cable connected to a main terminal or distribution hub provides connectivity for several cable data modems and receiver boxes in a neighborhood or community, in the conventional manner. When there is a power failure, the invention prevents failure in the HFC cable supply network and in the subscriber's modem and telephone.

According to the invention, a cable access network includes a trunk cable amplifier, connected by a coaxial cable to a plurality of cable data modems, to provide backup power to the cable modems during the power outages experienced. either by the trunk amplifier or the modems, therefore ensuring an uninterruptible IP telephony service. The trunk amplifier amplifies a DC (direct current) voltage along the coaxial cable conductors. An AC / DC converter and power regulator and also a backup battery are power sources for the DC voltage applied to the coaxial cable. A power cut sensor selectively connects either the AC / DC converter and power regulator or, alternatively, the backup battery to the cable, depending on whether a power cut is detected in the trunk amplifier. According to the invention, each cable data modem connected to the trunk amplifier is divided into voice IP circuits and other circuits that do not contribute to the voice IP function. The other circuits include, for example, video / audio receiver circuits and IP data transceiver circuits. The voice IP circuits are connected to the subscriber's telephone device. The cable data modem applies a DC voltage to the voice IP circuits and the subscriber's handset. An AC / DC converter and regulator in the modem and also the DC voltage of the coaxial cable are power sources for the DC voltage applied to the voice IP circuits. A power cut sensor selectively connects the voice IP circuits to either the AC / DC converter and power regulator in the modem or, alternatively, to the DC voltage of the coaxial cable, depending on whether there is a power cut detected in the cable data modem. Other circuits such as video / audio receiver circuits and IP data transceiver circuits are powered only by the AC / DC converter and power regulator in the cable data modem. In this way, if there is a general power cut that affects both the trunk amplifier and several of the cable data modems connected to it, the energy to be supplied by the backup battery in the trunk amplifier is only required for provide power to the voice IP circuits and the subscriber's telephone device. The invention is a cost-effective solution for providing an uninterruptible telephone service in an HFC cable network, in the face of power outages anywhere from the main terminal of the wired network to the subscriber's telephone.

DESCRIPTION OF THE FIGURES Figure 1 is a complete network diagram of a cable access network, according to the invention.

Figure 2 is a functional block diagram of a cable trunk amplifier and the cable data modem, according to the invention.

Figure 3 is a more detailed functional block diagram of the cable data modem, according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The communications network topology according to the invention is shown in the network diagram of Figure 1. The main terminal or distribution hub 110 is connected to an Internet Protocol network which may be a wide area network or a local area network 100. The external network 100 may have a network layer such as IP, IPX, X.25, or Apple Talk on the surface of an appropriate link layer or may have only one link layer such as Ethernet, ATM, FDDI, token ring network, IEEE 802.3, IEEE 802.12. It also connects to a telephone network which can be the public switching telephone network or a private telephone network 102. It also connects to a source of video channels and FM 104 audio channels. Two standards for the transmission of data by the Cable networks are: (1) The IEEE 802.14 Cable TV Access Method and the Physical Layer Specification; and (2) The ITU J112 Data Standard specification in the Cable Service Interface (DOCSIS). These standards define the modulation and protocols for bidirectional high-speed cable data transmissions.

The main terminal or distribution hub 110 operates to distribute these signals over the hybrid fiber / coaxial cable (HFC) network to the cable data modems (CDM) connected to the respective coaxial cable distribution routes. The hybrid fiber / coaxial cable network shown in Figure 1 extends to the CDM modems, and includes the main terminal as well as the cables. Each hybrid fiber / coaxial cable, for example HFC (0), includes a fiber optic component connected to the main terminal 110 that goes through the optical fiber node FN (0) to the electrical transducer and through an interface 106 within of the coaxial cable distribution portion of the network consisting of a trunk amplifier AMP (0), for example, which sends via a coaxial cable C (0), for example, the electrical analog of the optical signals in the portion of fiber optic cable. The electrical signals are exchanged with the respective data modems by cable, CDM (002), for example, as shown in Figure 1. The CDM cable data modem (002), for example, is shown connected to a device conventional telephone P (002). The hybrid fiber / coaxial cable connected to the main terminal 110 provides connectivity for several cable data modems in a neighborhood or community, in the conventional manner. The AMP trunk amplifier (O), for example, has a backup battery B (0), which may be, for example, a lead acid battery, a solar cell battery, a fuel cell battery, or the like. The B (0) battery must be able to supply sufficient backup power during a power cut in the trunk amplifier to supply DC power to those voice IP circuits in use during the cut. For example, the average DC power consumption of voice IP circuits in a cable data modem is 10 watts. In addition, there are 100 data modems per cable connected to the trunk amplifier. And in addition, there are no more than 25 telephone subscribers who need to use their phone during a power outage. Then, the electrical energy that is required from the backup battery in the trunk amplifier is 250 watts. For this example, a conventional 105 amp-hour lead acid battery can supply a sufficient amount of backup power for a period of five hours.

When a cable connection to a main terminal 110 is accidentally interrupted-for example, by the loss of electrical power to the AMP amplifier (O) or to the CDM cable data modems (002) - the service can be quickly restored to the modems of affected cable data attached to the cable, by the invention described herein.

Figure 2 is a functional block diagram of the cable trunk amplifier and the cable data modem according to the invention. According to the invention, the cable access network includes the AMP (0) cable trunk amplifier, connected by the coaxial cable C (0) to a plurality of cable data modems including the CDM modem (002), for provide backup power to cable modems during power outages experienced by the trunk amplifier or modems, thus ensuring an uninterruptible IP telephony service. The CDM data cable modem (002) is connected to a conventional telephone device P (002), which also takes its power from the modem.

The amplifier AMP (O) applies a DC voltage V (DC) along the coaxial cable conductors C (0). An AC / DC power converter and regulator 204 connected to the AC source 210 and also a backup battery B (0) are power sources for the DC voltage V (DC) applied to the coaxial cable C (0). A power cut sensor 206 selectively connects the AC / DC power converter and controller 204 or, alternatively, the backup battery B (0) to the C (0) cable, depending on whether there is a power cut detected in the amplifier AMP trunk (0). The RF amplifier 202 in the amplifier AMP (0) amplifies the RF V (RF) signal from the main terminal, which is coupled through the line capacitor 208 to the coaxial cable C (0) connected to the CDM cable modem (002 ). The resulting voltage signal on cable C (0) is the sum of V (DC) + V (RF), which is provided to the cable data modem CDM (002).

According to the invention, each CDM data modem (002) is divided into voice IP circuits 230 and other circuits that do not contribute to the voice IP function. The other circuits include, for example, video / audio receiver circuits 226 and IP data transceiver circuits 228. The voice IP circuits 230 are connected to the subscriber's telephone apparatus P (002) on line 242. The data modem is The CMD cable (002) applies a DC voltage V (DC) 'to the voice IP circuits 230 and to the subscriber's telephone apparatus P (002). The line capacitor 224 connects the RF V (RF) signal of the C (0) cable with the line 222 to the video / audio receiving circuits 226, the IP data transceiver circuits 228, and the voice IP circuits 230. Line 220 provides voltage V (DC) of cable C (0) via line 220 to power cut-off sensor 236 for voice IP circuits 230. An AC / DC converter and power regulator 232 in the CDM modem ( 002) supplied by the AC source 234 and also the DC voltage V (DC) of the coaxial cable C (0) are power sources for the DC voltage V (DC) 'applied to the voice IP circuits 230. The sensor of power cut 236 selectively connects voice IP circuits 230 to the AC / DC 232 power converter and controller via line 238 on the CDM modem (002) or, alternatively, the DC voltage V (DC) of the coaxial cable C (0) via line 240, depending on whether there is a power cut detected in the CDM data modem (002). The other circuits such as the video / audio receiver circuits 226 and the IP 228 data transceiver circuits are powered only by the voltage V (PS) of the AC / DC converter and power regulator 232 in the cable data modem. CDM (002). In this way, if there is a general power cut that affects both the AMP (0) trunk amplifier and several of the cable data modems connected to it, the power to be supplied by the backup battery B (0) in the trunk amplifier is only required to provide power to voice IP circuits 230 and subscriber telephone apparatus P (002). The invention is a cost effective solution for providing uninterruptible telephone service in an HFC cable network, in the face of power outages anywhere from the main terminal of the wired network to the subscriber's telephone.

Figure 3 is a more detailed functional block diagram of the data modem, according to the invention. The figure shows details of the voice IP circuits 230, which include the DC / DC power converter and regulator 302 which receives the voltage V (DC) through the line 240 of the power cut sensor 236. The converter and regulator of DC / DC 302 power supplies DC voltage to the Flash ROM, DRAM 304, to the microcontroller 306, to the digital voice CATV RF channel CATV receiver and to the transmitter up line 308 via line 310. The converter and DC / DC power regulator 302 also supplies DC voltage to the analogue telephone interface RJ11 312 which is connected via line 242 to telephone set P (002). The bus 314 distributes the voice signals between the Flash ROM, RAM 304 memory, the microcontroller 306, the digital voice CATV RF channel CATV receiver and the upstream transmitter 308, and the interface 312 of the analog telephone RJ11.

Two examples of the power cut sensor 206 in the AMP trunk amplifier (O) and the power cut sensor 236 in the CD data modem CD (002) are given in US Patent 5,457,414, to which reference was made. previously, entitled "Sensor of Loss of Power Supply" by David A. Inglis and Hyun Lee, assigned to AT &T CORP and incorporated here as a reference. In Figure 8 of Inglis et al., Data corruption or system malfunction due to losses of the primary supply of DC power is commonly prevented using a "diode-switch" method. Figure 8 of Inglis et al. Shows two diodes external to the system device (e.g., an integrated circuit), and connected in such a way that one diode deflects in reverse and the other diode deflects forward. This type of solution is acceptable if the voltage level V (PS) is sufficiently high so that a drop in the diode voltage can still provide a solid energy supply voltage V (DC) to the system, which is usually true if the V (PS) is 5V (plus or minus 10 percent). However, in the case that the V (PS) is 3V (plus minus 5 percent) to provide power to an integrated circuit, using the method in Figure 8 of Inglis et al. Results in a voltage range. from only 2.2 V to 2.5 V (that is, V (PS) minus the voltage drop in the diode). This level of power supply voltage (2.2 V to 2.5 V) can degrade the operation of a logic circuit to a point where it is not acceptable. For example, the rate of degradation due to the decrease in the power supply from 3V to 2.2 V is typically a factor of 2. Inglis et al. Describe another loss of power supply sensor in greater detail. The second Energy Loss Sensor circuit shown in Figures 1-7 of Inglis et al. Detects the loss of a power supply voltage in a system that includes a primary and backup power supply. One or both of the energy sources are typically batteries; for example, a rechargeable battery can be the primary source of energy, and a long-lasting battery (for example, lithium or alkaline) can be the backup, other sources of energy being possible. The loss sensor detects a gradual degradation or total loss of V (PS), the primary energy supply to the system. Both the primary power supply and the backup power supply can be removed from the system at any time and the circuit will maintain power in a portion of the system, using the remaining power supply. The loss sensing circuit is designed with all-digital logic or low-energy equivalent components, therefore minimizing energy dissipation and increasing its versatility. That is, this circuit can be manufactured with either a digital or analog integrated circuit manufacturing process.

The invention is a cost-effective solution for providing an uninterruptible telephone service in an HFC cable network, in the face of power outages anywhere from the main terminal of the wired network to the subscriber's telephone.

Several illustrative examples of the invention have been described in detail. However, further modifications and changes to these examples may be made without departing from the nature and spirit of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (1)

1. CLAIMS l.A cable access network, characterized in that it comprises: a trunk amplifier for cable connected by a coaxial cable to a plurality of cable data modems; a main power source and a backup power source in said cable trunk amplifier to apply a DC voltage to the coaxial cable; a power cut sensor in said cable trunk amplifier that selectively connects the main power source or the backup power source to the cable, depending on whether there is a power cut in the trunk amplifier; at least one cable data modem connected to the trunk amplifier, said modem being divided into IP voice circuits and other circuits that do not contribute to an IP voice function; a local source of primary power in the modem and the DC voltage of the coaxial cable to provide power sources for the IP voice circuits; and a local power cut-off sensor in the modem to selectively connect the IP voice circuits to the local source of main power or to the DC voltage of the coaxial cable, depending on whether there is a power cut detected in the cable data modem. . The cable access network according to claim 1, characterized in that it additionally comprises: said IP voice circuits connected to the subscriber's telephone apparatus which is supplied with power by means of the cable data modem. The cable access network according to claim 1, characterized in that it additionally comprises: said other circuits including video / audio receiver circuits and IP data transceiver circuits. SUMMARY OF THE INVENTION A cable access network includes a trunk amplifier for cable connected by a coaxial cable to a plurality of cable data modems to provide backup power to the cable data modem during power outages experienced by the trunk amplifier or modems, thus ensuring the uninterruptible IP telephone service. The trunk amplifier applies a DC voltage along the coaxial cable conductors. An AC / DC converter and power regulator and also a backup battery are power sources for the DC voltage applied to the coaxial cable. A power cut sensor selectively connects the AC / DC converter and power regulator or, alternatively, the backup battery with the cable, depending on whether there is a power cut detected in the trunk amplifier. Each cable data modem connected to the trunk amplifier is divided into IP voice circuits and other circuits that do not contribute to the IP voice function. The other circuits include, for example, video / audio receiver circuits and IP data transceiver circuits. The IP voice circuits are connected to the subscriber's telephone device. The cable data modem applies a DC voltage to the IP voice circuits and the subscriber's telephone device. An AC / DC converter and regulator in the modem and also the DC voltage of the coaxial cable are power sources for the DC voltage applied to the IP voice circuits. A power cut sensor selectively connects the IP voice circuits to the AC / DC converter and power regulator in the modem or, alternatively to the DC voltage of the coaxial cable, depending on whether there is a power cut detected in the data modem by cable. Other circuits such as video / audio receiver circuits and IP data transceiver circuits are powered only by the AC / DC converter and power regulator in the cable data modem. In this way, if there is a general power cut that affects both the trunk amplifier and several of the cable data modems connected to it, the energy to be supplied by the backup battery in the trunk amplifier is only required to supply power to the IP voice circuits and the subscriber's telephone device.