Low-powered communication system and method of operation

• US 6,690,655 B1
• Filed: 10/19/2000
• Issued: 02/10/2004
• Est. Priority Date: 10/19/2000
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Miner, Mark Charles, Cooper, Michael Jaimie
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US09/692,427
• Time in Patent Office: 1,209 Days
• Field of Search: 379/93.01, 348/9, 455/5.1, 455/561, 455/4.1, 455/4.2, 455/450, 370/395, 370/508, 370/458, 370/294, 370/421, 370/356, 370/329, 370/486, 370/347, 370/348, 370/295, 370/442, 370/281, 370/466, 370/467, 370/311, 370/278, 370/343, 370/430, 370/480, 710/8, 725/88
• US Class Current: 370/278
• CPC Class Codes: H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

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. Alternatively, the RIU may transition from standby mode to active mode on its own upon detecting a desire (e.g., off-hook signal) by the RIU'"'"'s associated communication device to communicate in the system. The secondary downstream channel utilizes a substantially slower transmission speed (e.g., a lower order modulation) than does the primary downstream channel, thereby enabling the RIU to consume substantially less power when in standby mode than when in active mode, without adversely impacting the throughput rate of the primary downstream channel.

Claims

1. A communication system comprising:

a remote interface unit that operates in accordance with a first downstream communication protocol when the remote interface unit is in a first mode of operation and operates in accordance with a second downstream communication protocol when the remote interface unit is in a second mode of operation, the first mode of operation consuming substantially less power than the second mode of operation;

a network control facility that controls communications involving the remote interface unit and routes information to and from the remote interface unit;

a first downstream channel for communicating control information from the network control facility to the remote interface unit in accordance with the first downstream communication protocol when the remote interface unit is in the first mode of operation, the first downstream channel operating at a first transmission rate, the control information at least instructing the remote interface unit to transition from the first mode of operation to the second mode of operation; and

a second downstream channel for communicating user information from the network control facility to the remote interface unit in accordance with the second downstream communication protocol when the remote interface unit is in the second mode of operation, the second downstream channel operating at a second transmission rate that is greater than the first transmission rate,

the first and second downstream channels responsive to establish access by the remote interface unit to the network control facility via a time division multiple access channel shared concurrently by a plurality of remote interface units.

2. The communication system of claim 1, wherein the first transmission rate comprises a rate resulting from applying one of frequency shift keying (FSK), quaternary phase shift keying (QPSK) and quadrature amplitude modulation (QAM) to the control information to be communicated over the first downstream channel.

3. The communication system of claim 2, wherein the second transmission rate comprises a rate higher than the first transmission rate communicated over the second downstream channel.

4. The communication system of claim 1, wherein the remote interface unit comprises:

a first receiver operably coupled to receive the user information communicated over the second downstream channel when the remote interface unit is in the second mode of operation;

a second receiver operably coupled to receive the control information communicated over the first downstream channel when the remote interface unit is in the first mode of operation;

a first processor operably coupled to the first receiver, the first processor processing the user information received by the first receiver when the remote interface unit is in the second mode of operation; and

a second processor operably coupled to at least the second receiver and the first processor, the second processor processing the control information received by the second receiver when the remote interface unit is in the first mode of operation and enabling at least the first processor responsive to the control information to transition the remote interface unit from the first mode of operation to the second mode of operation.

5. The communication system of claim 1, wherein the first mode of operation is a standby mode of operation and wherein the second mode of operation is an active mode of operation.

6. The communication system of claim 1, wherein the network control facility comprises headend equipment of a two-way hybrid fiber coaxial cable system.

7. The communication system of claim 1, wherein the communication system further includes an upstream channel for communicating information from the remote interface unit to the network control facility in accordance with an upstream communication protocol and wherein the network control facility receives information packets from an external network for delivery to the remote interface unit, the network control facility comprising:

an external network interface for receiving at least one information packet intended for the remote interface unit;

a first transmitter, operably coupled to the external network interface, the first transmitter transmitting the control information over the first downstream channel responsive to receiving at least one information packet;

an upstream channel receiver operably coupled to receive an acknowledgment packet from the remote interface unit over the upstream channel responsive to transmission of the control information; and

a second transmitter, operably coupled to the external network interface, the second transmitter transmitting at least one information packet over the second downstream channel responsive to receipt of the acknowledgment packet.

8. The communication system of claim 1, wherein the user information communicated over the second downstream channel comprises at least one of audio information, video information, and data information.

9. A remote interface unit for use in a two-way communication system that includes a network control facility, the network control facility controlling communications involving the remote interface unit, the remote interface unit comprising:

a first receiver for receiving control information from the network control facility over a first downstream channel when the remote unit is in a first mode of operation;

a first processor operably coupled to the first receiver, the first processor processing the control information received by the first receiver when the remote unit is in the first mode of operation and enabling at least the first processor responsive to the control information to transition the remote interface unit from the first mode of operation to the second mode of operation;

a second receiver for receiving user information from the network control facility over a second downstream channel when the remote unit is in a second mode of operation, the second downstream channel operating at a transmission rate that is greater than a transmission rate of the first downstream channel and the second mode of operation consuming substantially more power than the first mode of operation; and

a second processor operably coupled to the second receiver, the second processor processing the user information received by the second receiver when the remote unit is in the second mode of operation,

the first and second processors responsive to establish, in the second mode of operation, access by the remote interface unit to the network control facility via a time division multiple access channel shared concurrently by a plurality of remote interface units.

10. The remote interface unit of claim 9, wherein the remote interface unit comprises a cable modem.

11. The remote interface unit of claim 9, further comprising an interface, operably coupled to at least the first processor and the second processor, for receiving information from an external communication device for communication to the network control facility over the upstream channel, wherein first processor may transition the remote interface unit from the first mode of operation to the second mode of operation responsive to detecting an indication that the external communication device desires to communicate information to the network control facility.

12. The remote interface unit of claim 11, wherein the interface comprises at least one of a telephone jack and/or a data port.

13. The remote interface unit of claim 11, wherein the indication that the external communication device desires to communicate information to the network control facility comprises an off-hook signal generated by the external communication device or a protocol signal or rule for non-telephony devices.

14. A two-way cable infrastructure system for communicating information to and receiving information from a remote interface unit, the two-way cable infrastructure system comprising:

headend equipment that controls communications involving the remote interface unit and routes information to and from the remote interface unit; and

a cable plant supporting a first downstream channel for communicating control information from the headend equipment to the remote interface unit in accordance with a first downstream communication protocol when the remote interface unit is in a first mode of operation, a second downstream channel for communicating user information from the headend equipment to the remote interface unit in accordance with a second downstream communication protocol when the remote interface unit is in a second mode of operation, and a time division multiple access upstream channel shared concurrently by a plurality of remote interface units, for communicating user information from the remote interface unit to the headend equipment in accordance with an upstream communication protocol, the second downstream channel operating at a transmission rate that is greater than a transmission rate of the first downstream channel, the first mode of operation consuming substantially less power than the second mode of operation, the control information at least instructing the remote interface unit to transition from the first mode of operation to the second mode of operation to facilitate communication of the user information, and the fist and second downstream channels responsive to establish, in the second mode of operation, access by the remote interface unit to the network control facility via the upstream channel.

15. An improved two-way cable communication system that includes headend equipment, a plurality of cable modems, a shared downstream channel for communicating information from the headend equipment to the plurality of cable modems in accordance with a downstream communication protocol, and a time division multiple access upstream channel shared concurrently by the plurality of cable modems for communicating information from the plurality of cable modems to the headend equipment in accordance with an upstream communication protocol, wherein the improvement comprises:

a second downstream channel for communicating a command from the headend equipment to the plurality of cable modems, the command instructing at least one cable modem of the plurality of cable modems to begin executing the downstream communication protocol for the first downstream channel, the second downstream channel operating at a transmission rate that is substantially less than a transmission rate of the first downstream channel,

the first and second downstream channels responsive to establish access by the at least one cable modem to the network control facility via the upstream channel.

16. A method for a network control facility to establish communication with a remote interface unit in a two-way communication system, the method comprising the steps of:

receiving user information intended for the remote interface unit;

determining whether the remote interface unit is in a first mode of operation;

communicating control information to the remote interface unit over a first downstream channel when the remote interface unit is in the first mode of operation, the control information instructing the remote interface unit to transition from the first mode of operation to a second mode of operation, the first mode of operation consuming substantially less power than the second mode of operation;

receiving an acknowledgment of receipt of the control information from the remote interface unit over a time division multiple access upstream channel shared concurrently by a plurality of remote interface units; and

communicating the user information to the remote interface unit over a second downstream channel responsive to receipt of the acknowledgment, the second downstream channel operating at a higher transmission rate than the first downstream channel,

the first and second downstream channels responsive to establish, in the second mode of operation, communication between the remote interface unit and the network control facility via the upstream channel.

17. The method of claim 16, wherein the control information includes an identification code associated with the remote interface unit.

18. The method of claim 16, wherein the control information indicates a duration of tune that the remote interface unit will be operating in the first mode of operation.

19. The method of claim 16, wherein the upstream channel utilizes a transmission protocol in which information is communicated in allocated time slots, wherein each time slot includes a fixed time period portion and a variable time period portion, and wherein the method further comprise the step of:

increasing the variable time period portion by a predetermined quantity of time to account for timing reference drift in the remote interface unit occurring while the remote interface unit was in the first mode of operation.

20. The method of claim 19, wherein the variable time period portion comprises a first guard time immediately preceding the fixed time period portion and a second guard time immediately succeeding the fixed time period portion.

21. The method of claim 19, wherein the control information includes an identification of a future time slot in which the remote interface unit is to communicate the acknowledgment over the upstream channel.

22. The method of claim 19, wherein the transmission protocol comprises the upstream transmission protocol specified in the Data-Over-Cable Service Interface Specification (DOCSIS).

23. The method of claim 22, wherein the acknowledgment comprises one of a DOCSIS periodic ranging and an initial ranging response message.

24. The method of claim 22, wherein the control information comprises one of a DOCSIS periodic ranging and an initial ranging response message.

25. The method of claim 19, further comprising the steps of:

receiving a status message over the upstream channel, the status message indicating that the remote interface unit has become time-synchronized with the network control facility; and

decreasing the variable time period portion by the predetermined quantity of time.

26. The method of claim 19, further comprising the steps of:

determining whether a predetermined period of time has expired since receipt of the acknowledgment; and

in the event that the predetermined period of time has expired, decreasing the variable time period portion by the predetermined quantity of time.

27. The method of claim 19 wherein a timing reference in the remote interface unit is used to track a timing reference in the network control facility to support effective use of the transmission slots, the method further comprising the steps of:

measuring the difference in oscillations between the network control facility time reference oscillator and the remote interface unit oscillator by measuring the difference in the number of oscillations over an extended period, the accuracy of this measurement being directly related to the reciprocal of the measurement duration; and

using this measured difference to support more accurate remote interface unit time reference tracking by adjusting the remote interface unit time reference to compensate for this measured difference.

28. The method of claim 16 wherein user information intended for a plurality of remote interface units is stored at the network control facility, wherein the network control facility determines that at least two of the intended remote interface units are in a first mode of operation, and wherein the step of communicating the control information comprises the step of:

broadcasting control information to the plurality of remote interface units in the first mode of operation over a first downstream channel, the control information instructing the plurality of remote interface units to transition from the first mode of operation to a second mode of operation, the first mode of operation consuming substantially less power than the second mode of operation.

29. A method for a remote interface unit to communicate in a two-way communication system, the method comprising the steps of:

operating in accordance with a first, low power mode of operation in which the remote interface unit is configured to receive control information from a network control facility over a first downstream channel;

receiving the control information over the first downstream channel;

responsive to receiving the control information, transitioning from the first mode of operation to a second mode of operation in which the remote interface unit is configured to receive at least user information from the network control facility over a second downstream channel, the second mode of operation consuming substantially more power than the first mode of operation and the second downstream channel operating at a higher transmission rate than the first downstream channel; and

responsive to transitioning to the second mode of operation, the remote interface unit configured to communicate with the network control facility via an upstream channel, the upstream channel comprising a time division multiple access channel shared concurrently by a plurality of remote interface units.

30. The method of claim 29, further comprising the step of:

transmitting an acknowledgment of receipt of the control information to the network control facility over the upstream channel responsive to receiving the control information.

31. The method of claim 30, wherein the upstream channel utilizes a transmission protocol in which information is communicated in allocated time slots, the method further comprising the step of:

synchronizing a timing reference of the remote interface unit with a timing reference of the network control facility responsive to receiving the control information.

32. The method of claim 31 further comprising the step of:

transmitting a status message over the upstream channel, the status message indicating that the remote interface unit has become time-synchronized with the network control facility.

33. The method of claim 31, wherein the control information includes an identification of a time slot in which the remote interface, unit is to communicate the acknowledgment over the upstream channel and wherein the step of transmitting the acknowledgment comprises the step of:

transmitting the acknowledgment in the time slot.

34. The method of claim 31, wherein the transmission protocol comprises the upstream transmission protocol specified in the Data-Over-Cable Service Interface Specification (DOCSIS).

35. The method of claim 34, wherein the acknowledgment comprises one of a DOCSIS periodic ranging and an initial ranging response message.

36. The method of claim 34, wherein the control information comprises one of a DOCSIS periodic ranging and an initial ranging response message.