Abstract: A topology discovery technique for automatically determining the network structure of a hybrid fiber coax or all coax cable plant is disclosed. The resulting topology is structured in terms of fiber nodes, amplifiers, and taps. The location of customer devices such as cable modems, set-top boxes, and telephony terminal adapters are identified within the resulting topology. The discovery technique relies on measurements made only at the headend location of the cable plant.

Abstract: In a cable modem system a method is provided for continuously monitoring the upstream channel to assess what unused upstream channels will better support data communication in the event that an active upstream channel degrades, with monitoring of the upstream path by using passive or unused channels not impacting active data transfer. In one embodiment, a single spectrum assessment receiver polls cable modems at various taps and has the selected modem retune itself to an unused channel and transmit a reference signal back to the spectrum assessment receiver. An analysis is made and an impaired active channel is identified to ascertain if it has degraded to an unacceptable level. If so, it is switched or hopped to this unused channel if by switching an improvement can be realized. Polling is accomplished by selecting the modem at the worst performing tap and ascertaining after one or more retunes which unused channel is best.

Abstract: In a system, device, and method for selecting a channel from among a plurality of channels, a number of available channels are selected for testing. A channel quality measurement is made for each of the number of available channels. The channel having the best channel quality measurement is then selected. To make the channel quality measurements, a primary station selects a channel to be tested and also selects a secondary station with which to perform the test. The primary station transmits a control frame to the selected secondary station, including a channel identifier identifying the selected channel. Upon receiving the control frame, the selected secondary station adjusts its transmitter to the selected channel based on the channel identifier in the control frame, and transmits a reference signal on the selected channel. Meanwhile, the primary station adjusts its receiver to the selected channel and receives the reference signal from the selected secondary station.

Abstract: A communication system includes a network control facility (205), two downstream channels (212, 213), at least one remote interface unit (209, 210), and at least one communication device (201, 202) associated with each remote interface unit (RIU). Each RIU operates in one of two operating modes: a low power, standby mode and a high power, active mode. One downstream channel (212) is the primary downstream channel and is used by the network control facility to communicate user information and normal maintenance or control information to the RIU when the RIU is in the active mode. The other downstream channel (213) is the secondary downstream channel and is used by the network control facility to communicate special control information, such as a wake-up command, to the RIU when the RIU is in standby mode. The wake-up command instructs the RIU to transition from standby mode to active mode in order to receive user or control information over the primary downstream channel.