Broadband communication network with low power addressable tap system for controlling subscriber access

• US 6,694,517 B1
• Filed: 08/27/1999
• Issued: 02/17/2004
• Est. Priority Date: 08/27/1999
• Status: Expired due to Fees

• Current Assignee: Diversified Control, Inc.
• Original Assignee: Diversified Control, Inc.
• Inventors: Page, John Douglas, James, Lewis Gregory
• Primary Examiner(s): Miller, John
• Assistant Examiner(s): Sloan, Nathan A
• Application Number:
  US09/384,352
• Time in Patent Office: 1,635 Days
• Field of Search: 725/149, 725/150, 725/127, 725/128, 725/129, 725/130, 725/107, 725/116, 725/124, 725/125, 725/7, 333/7, 333/611, 709/7, 713/320, 713/310
• US Class Current: 725/127
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/165 Centralised control of user terminal subsequent to an upstream request signal H04N7/17345; Registering at central by two-way working H04N7/17309

Abstract

A broadband telecommunication network (such as a cable television distribution system) includes a plurality of switching units (such as taps) controlling subscriber access to the network. The switching units are controlled from a central location (such as a head end) using minimal network transmission medium power. A repeating sequence of switching unit control messages is sent from the central location across the network. Each of the messages is addressed to an individual one of the switching units. Each switching unit is periodically powered up from a low power sleep state to a higher power operational wake state in synchronization with a corresponding one of the control messages being sent from the central location. After a switching unit'"'"'s corresponding control message is processed, the switching unit is returned to the lower power sleep state.

Claims

1. In a broadband telecommunication network including a plurality of microprocessor-controlled switching units controlling subscriber access to the network, a method for controlling said switching units from a central location using minimal network transmission medium power, comprising the steps of:

sending a repeating sequence of switching unit control messages from said central location across said network, each of said messages being addressed to an individual one of said switching units by way of a switching unit address contained in each message;

periodically powering each of said switching units from a low power (sleep) state to a higher power operational (wake) state in synchronization with a corresponding one of said control messages being sent from said central location, and thereafter returning said switching units to said sleep state;

said sleep state being implemented without microprocessor control by way of a programmable timer that is programmed at the end of each wake state to count for a programmed sleep period that is determined by calculation during said wake state;

said wake state being implemented with microprocessor control as a result of said timer asserting a wakeup signal at the end of said programmed sleep period; and

said programmed sleep period being calculated by way of a computation that includes comparing a switching unit address received dung said wake state with a switching unit address assigned to said switching unit and adjusting said programmed sleep period if said received switching unit address differs from said assigned switching unit address by a predetermined threshold.

2. A method in accordance with claim 1 wherein the current consumption of said switching units during said sleep state is approximately 2-3 orders of magnitude less than the current consumption of said switching units during said wake state.

3. A method in accordance with claim 1 wherein said sleep state consumes substantially no current from said network.

4. A method in accordance with claim 1 wherein said switching units are powered into said wake, state each time a corresponding one of said control messages is sent from said central location.

5. A method in accordance with claim 4 wherein said switching units are powered into said wake state several control messages in advance of the corresponding one of said control messages and remain in said operational state until the corresponding one of said control messages is processed.

6. A method in accordance with claim 1 wherein not more than eight of said switching units are placed in said wake state at any given time.

7. A method in accordance with claim 1 wherein said switching units are powered by said network during said sleep state and said wake state.

8. A method in accordance with claim 1 wherein said switching units are self powered during said sleep state and powered by said network during said wake operational state.

9. A method in accordance with claim 1 wherein said switching units function during said sleep state by timing the arrival of a corresponding one of said control messages and then invoke said wake state.

10. A method in accordance with claim 9 wherein said switching units function during said wake state by:

(1) reading the addresses of said control messages until a corresponding one of said control messages is detected;

(2) processing said detected control message and taking responsive action if necessary;

(3) calculating said programmed sleep period as a time period until a subsequent corresponding one of said control messages will be sent; and

(3) returning said switching unit to said sleep state to time the arrival of said subsequent control message using said calculated time period.

11. A method in accordance with claim 1 wherein said broadband communication network is a cable television distribution system, said central location is a head end, and said switching units are addressable taps connected to cable transmission lines carrying communications from said head end.

12. A method in accordance with claim 11 wherein said taps contain multiple switchable subscriber connection ports and wherein said control messages are tap records that include a field containing switch state information for each port in a tap.

13. In a cable television distribution system including (1) a head end, (2) at least one transmission line carrying communications from said head end, and (3) a plurality of taps connected to said transmission lines and containing switchable microprocessor-controlled ports connecting to cable subscribers, a low power system for controlling the switch state of said ports in said taps, comprising:

a tap record generating circuit in said head end for generating a repeating sequence of tap records, each tap record containing a tap address for identifying a specific one of said taps and containing information for controlling the switch state of said ports;

a tap control circuit in each of said taps, each tap circuit including a low power stage and a higher power stage;

said low power stage being implemented without microprocessor control by way of a programmable timer that is programed at the end of each wake state to count for a programmed sleep period that is determined by calculation during said wake state, said low power stage being configured to control said higher power stage by maintaining it in a sleep state until a corresponding tap record is about to be sent by said head end, and to wake up said higher power stage to process said tap record;

said higher power stage being implemented with microprocessor control as a result of said timer asserting a wakeup signal at the end of said programmed sleep period, said higher power stage being configured to read tap records as they arrive from said head end, to identify a corresponding tap record, to process said tap record by setting the switch state of said ports as necessary in response to said tap record, to calculate a time interval for reawakening, to provide said time interval to said low power stage, and to return itself to said sleep state;

said time interval being calculated by way of a computation that includes comparing a tap address received during said wake state with a tap address assigned to said tap and adjusting said time interval if said received tap address differs from said assigned tap address by it predetermined threshold.

14. An addressable tap for use in a cable television distribution system, comprising:

an input adapted to receive radio frequency and power signals from a cable plant;

a plurality of switchable tap ports adapted to selectively output a radio frequency signal received at said input;

a radio frequency receiver adapted to receive said radio frequency signal from said input, demodulate said radio frequency signal, and extract tap record data therefrom containing tap port switch settings;

a microprocessor controller adapted to receive said tap record data and control the selection of said switchable ports for radio frequency signal output based on tap records in said tap record data that are addressed to said addressable tap;

a power supply adapted to receive said power signal from said input and provide power to said microprocessor and said receiver;

a programmable timer circuit adapted to control power delivery from said power supply;

said timer circuit including a timer that is adapted to operate during a low power (sleep) state of said addressable tap without microprocessor control to periodically assert a timer output signal;

said timer output signal allowing power to be provided to said microprocessor so that said addressable tap is placed into a higher power operational (wake) state in which said addressable tap is under microprocessor control;

said microprocessor being further adapted to return to said sleep state after processing said tap record data by programming said timer circuit to assert a next timer output signal based on a wakeup interval calculated by said microprocessor during said wake state; and

said wakeup interval being calculated by way of a computation that includes comparing a tap address received in a tap record during said wake state with a tap address corresponding to said addressable tap and adjusting said wakeup interval if said received tap address differs from said corresponding tap address by a predetermined threshold.

15. An addressable tap in accordance with claim 14 wherein said addressable tap is adapted to immediately enter said wake state following an interruption of said power signal from said cable plant.

16. An addressable tap in accordance with claim 15 wherein said power supply is adapted to detect said power signal interruption and output a power pulse signal to said timer circuit, and wherein said timer circuit is adapted to assert power to said microprocessor in response to said power pulse without regard to said timer output signal.

17. An addressable tap in accordance with claim 14 wherein said microprocessor is adapted to control power to said receiver.

18. An addressable tap in accordance with claim 14 wherein said microproccessor is adapted to control the frequency setting of said receiver.

19. An addressable tap in accordance with claim 14 wherein said microprocessor is programmed to check tap addresses in said tap record data to determine whether a tap address in said tap record data corresponds to said addressable tap, and if so, to process the tap record associated with said tap address.

20. An addressable tap in accordance with claim 19 wherein said microprocessor is programmed to detect space words in said tap records in order to distinguish between successive tap records.

21. An addressable tap in accordance with claim 19 wherein said microprocessor is programmed to compute a new wake up interval and return to said sleep state if said tap addresses being checked are less than the tap address corresponding to said addressable tap by a predetermined threshold and thereby indicating that said addressable tap has awoken too early, and to also return to said sleep state if said tap addresses being checked are greater than the tap address corresponding to said addressable tap and thereby indicating that said addressable tap has awoken too late.

22. An addressable tap in accordance with claim 19 wherein said microprocessor stores one or more of tap address information, tap data frequency information, tap port data, and tap mode data, Wherein said tap record data includes corresponding information, and wherein said tap record processing includes updating said stored information if it is changed in a tap record addressed to said addressable tap.

23. An addressable tap in accordance with claim 19 wherein said tap record processing includes setting said tap ports according to tap port switch settings in a tap record addressed to said addressable tap.