Embodiments of the present invention are directed generally to cable network fault location and more specifically to a system and method for displaying the location of non-responding set top boxes (STBs) and cable modems (CMs) graphically, relative to the location of cable network components.
Cable networks deliver voice, data, and video to subscribers over a complex network of headends, regional data centers, hubs, and nodes. At the upstream terminus of the network is the headend and regional data center. Typically, a head end comprises the analog and digital video signal processors, video on demand systems, and other video content management devices. A regional data center comprises digital service management devices (e-mail servers, DNS, and Internet connectivity) and routers that interconnect the regional data center with a headend. A hub receives the video and data signals from the headend and regional data center, processes these signals through appropriate modulators, and sends these signals downstream to a hub. The hub provides the signals to a node that is ultimately associated with individual subscribers. A node provides an interface between the fiber-based component of the HFC cable network and the RF/cable component of the network that is the transport media to the home.
In a commercial network, a headend may service multiple hubs and a hub may service multiple nodes. A regional data center may provide digital services to multiple headends. From a node to the home, the RF/cable component of the HFC cable network may branch numerous times. Amplifiers, line extenders, and passive devices are employed to maintain signal quality across all branches (or “cascades”) serviced by the node.
FIG. 1 illustrates typical prior art cable system architecture. A headend 100 comprises a network control system 102 that handles set-top provisioning, system management and interactive session set-up, a video signal processor 104 that handles content acquisition and delivery, 256 QAM Modulators 111 that generate modulated RF streams of digital video signals, a high speed data interface 106, and a billing system 107.
Headend 100 communicates with hub 108. Hub 108 comprises a cable modem termination system 110, a 256 QAM modulator 112 for downstream data traffic, a QPSK modulator for downstream Out-of-Band Data traffic 114, and a QPSK demodulator 116 for upstream Out-of-Band Data traffic. As will be appreciated by those skilled in the art, a hub may comprise multiple instances of each device illustrated in FIG. 1.
Hub 108 communicates with nodes 120A, 120B and 120C. Nodes 120 provide an interface between the fiber-based transport medium of the cable network (between the headend 100 and upstream side of nodes 120) and the coax-based medium (between the downstream side of nodes 120 and the taps 145). The downstream side of node 120B is further illustrated as connecting to trunk amplifier 1 125 which in turn is connected to trunk amplifier 2 130. The serial path from node 120B through trunk amplifier 1 125 to trunk amplifier 2 130 is referred to as a cascade relative to node 120B. Trunk amplifier 1 125 has three branches that are cascades relative to trunk amplifier 1 125 and sub-cascades relative to node 120B.
As will be appreciated by those skilled in the art, FIG. 1 is a greatly simplified schematic of cable network architecture. A hub typically serves 20,000 subscribers. A typical hub supports from 50 to 100 nodes with each node capable of serving 250 to 2000 subscribers. In order to maintain signal quality and quality of service commitments, trunk amplifiers maintain high signal quality. Internal trunk modules in the trunk amplifiers boost signals for delivery to subscribers' homes. Line Extender amplifiers maintain the high signal levels in cascades after the trunk amplifiers, through the neighborhoods. Taps divide out small amounts of signal for connection to the homes. Nominal cascade limits are up to 4 trunk amplifiers followed by up to 3 line extenders, with more in very rural areas. In suburban areas, cascades typically comprise 2 trunk and 2 line extenders. Because branching is unlimited, the total device count per node may be large despite short cascades.
At the downstream end of the network is the customer premises equipment (CPE). Referring again to FIG. 1, tap 145 connects a set top box (STB) 150 and a cable modem (CM) 155 to the HFC cable network via drop 147. The CPE receives content from a headend or regional data center and provides access to it by a subscriber. For example, video programming is delivered to STB 150 and high speed data services are delivered to CM 155.
The complexity of cable networks makes network fault isolation and maintenance a challenging task. The task can be partitioned into four stages:                determining that a failure has occurred or is imminent;        determining what has failed;        determining where in the network the failure is likely to be; and        determining what equipment is required to remedy, or prevent, the failure.        
A failure in any of the system components that provide services will ultimately cause subscribers to complain. However, relying on subscriber complaints to identify network faults is not only bad for business but, in many situations, too imprecise to be helpful. Further, customer complaints represent the existence of a problem rather than forecast that a problem is developing. Reliance on such data alone for network fault isolation and maintenance precludes proactive responses by the cable operator.
Structural and procedural concepts for isolating and correcting faults in network components and CPE have been disclosed in U.S. patent application Ser. No. 11/040,391, filed Jan. 21, 2005, for “A Fault Isolation System And Method;” in U.S. patent application Ser. No. 11/069,155, filed Mar. 1, 2005, for “An Early Warning Fault Identification And Isolation System For A Two-Way Cable Network;” in U.S. patent application Ser. No. 11/069,156, filed Mar. 1, 2005, for “A Fault Detection And Isolation System For An HFC Cable Network And Method Therefor;” and U.S. patent application Ser. No. 11/069,080 filed Mar. 1, 2005 for “A System And Method For Identifying And Isolating Faults In A Video On Demand Provisioning System.” The Ser. No. 11/040,391, the Ser. No. 11/069,155, the Ser. No. 11/069,156 and the Ser. No. 11/069,080 applications are incorporated herein in their entirety for all purposes.
Having determined that a problem in an HFC cable network has occurred, it is important to provide information to those responsible for taking remedial action as to the location of the fault and its possible causes. In particular, when field personnel are dispatched to correct problems affecting CPE, it would be very useful to understand the location of network components (hardware and transmission media) relative to the affected CPE. Typically, location information is provided in the form of printed address lists or maps.
What would be useful would be an interactive, computer-based fault management tool comprising an interactive map having data layers reflective of the street location of CPE relative to components of the physical plant (fiber, coax, and network devices). Such a fault management tool would display information relating to the state of a CPE unit and the state of a component of the physical plant. Additionally, the fault management tool would apply algorithms to fault data to identify possible common sources of a fault.