Synchronization of distributed cable modem network components
First Claim
1. A method for synchronizing operation of distributed cable modem termination system components, the method comprising:
- transmitting a plurality of data packets from a head end to a downstream transmitter hub via a packet data network, each data packet marked with a measured delay Quality of Service (QoS) indicator and including a time stamp based upon a clock of the head end and a delay tag;
receiving the plurality of data packets at the downstream transmitter hub;
smoothing, by the downstream transmitter hub, the time stamps of the plurality of data packets based upon corresponding delay tags;
based upon the smoothed time stamps, synchronizing a clock of the downstream transmitter hub with the clock of the head end; and
synchronizing a clock of an upstream receiver hub with the clock of the downstream transmitter hub.
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0 Petitions
Accused Products
Abstract
A distributed CMTS includes a head end, a downstream transmitter hub, and an upstream receiver hub. The head end transmits data packets to the downstream transmitter via a coupling packet data network. Each data packet is marked with a “measured delay” Quality of Service (QOS) and includes a time stamp that is based upon a clock of the head end and a delay tag. The downstream transmitter hub receives the plurality of data, adjusts the time stamps based upon the delay tags, smoothes the time stamps of the plurality of data packets and, based upon the smoothed time stamps, synchronizes its clock with the clock of the head end. The downstream transmitter hub then synchronizes a clock of the upstream receiver hub with the clock of the downstream transmitter hub. The upstream receiver hub may synchronize its clock to the clock of the head end using this technique.
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Citations
22 Claims
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1. A method for synchronizing operation of distributed cable modem termination system components, the method comprising:
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transmitting a plurality of data packets from a head end to a downstream transmitter hub via a packet data network, each data packet marked with a measured delay Quality of Service (QoS) indicator and including a time stamp based upon a clock of the head end and a delay tag;
receiving the plurality of data packets at the downstream transmitter hub;
smoothing, by the downstream transmitter hub, the time stamps of the plurality of data packets based upon corresponding delay tags;
based upon the smoothed time stamps, synchronizing a clock of the downstream transmitter hub with the clock of the head end; and
synchronizing a clock of an upstream receiver hub with the clock of the downstream transmitter hub. - View Dependent Claims (2, 3, 4, 5)
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7. A method for synchronizing operation of distributed cable modem termination system components, the method comprising:
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transmitting a plurality of data packets from a head end to an upstream receiver hub via a packet data network, each data packet marked with a measured delay Quality of Service (QoS) indicator and including a time stamp based upon a clock of the head end and a delay tag;
receiving the plurality of data packets at the upstream receiver hub;
smoothing, by the upstream receiver hub, the time stamps of the plurality of data packets based upon corresponding delay tags;
based upon the smoothed time stamps, synchronizing a clock of the upstream receiver hub with the clock of the head end; and
synchronizing a clock of a downstream transmitter hub with the clock of the upstream receiver hub. - View Dependent Claims (6, 8, 9, 10, 11, 12)
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13. A distributed cable modem termination system comprising:
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a downstream transmitter hub;
an upstream receiver hub;
a head end communicatively coupled to the downstream transmitter hub and to the upstream receiver hub by a packet data network;
wherein the head end is operable to transmit a plurality of data packets to the downstream transmitter hub via a packet data network, each data packet marked with a measured delay Quality of Service (QoS) indicator and including a time stamp based upon a clock of the head end and a delay tag; and
wherein the downstream transmitter hub is operable to;
receive the plurality of data packets at the downstream transmitter hub;
smooth the time stamps of the plurality of data packets based upon corresponding delay tags;
synchronize a clock of the downstream transmitter hub with the clock of the head end based upon the smoothed time stamps; and
synchronize a clock of the upstream receiver hub with the clock of the downstream transmitter hub via interaction with the upstream receiver hub. - View Dependent Claims (14, 15, 16, 17)
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18. A distributed cable modem termination system comprising:
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a downstream transmitter hub;
an upstream receiver hub;
a head end communicatively coupled to the upstream receiver hub and to the downstream transmitter hub by a packet data network;
wherein the head end is operable to transmit a plurality of data to the upstream receiver hub via a packet data network, each data packet marked with a measured delay Quality of Service (QoS) indicator and including a time stamp based upon a clock of the head end and a delay tag; and
wherein the upstream receiver hub is operable to;
receive the plurality of data packets at the upstream receiver hub;
smooth the time stamps of the plurality of data packets based upon corresponding delay tags;
synchronize a clock of the upstream receiver hub with the clock of the head end based upon the smoothed time stamps; and
synchronize a clock of the downstream transmitter hub with the clock of the upstream receiver hub via interaction with the downstream transmitter hub. - View Dependent Claims (19, 20, 21, 22)
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Specification