Method and apparatus for supporting TDMA operating over hybrid fiber coaxial (HFC) or other channels
First Claim
1. A time division multiple access (TDMA) communication network comprising:
- channel synchronizing means for synchronizing channels in a downstream direction towards users of the communication network comprising;
a timebase timer for generating time markers comprising modulo N-bit programmable cyclical reference counts that are incremented at a predetermined frequency and are reset to 0 when the reference counts reach a predefined value; and
at least one time marker insertion unit, each time marker insertion unit comprising a first input terminal for receiving a digital TDMA transport stream having a predetermined data rate and comprising data packets and Media Access Control (MAC) packets that are interspersed between the data packets at predetermined intervals, a second input terminal for receiving the time markers generated by the timebase timer and for inserting a currently received time marker count into a currently received MAC packet, and an output terminal for transmitting the received TDMA data stream with the inserted time marker counts in the MAC packets in a continuous output TDMA transport stream to remote user terminals where the time markers are independent of a data rate, a physical channel, and a channel protocol of the transport stream and are used for synchronizing the user terminals.
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Accused Products
Abstract
In a Time Division Multiple Access (TDMA) communication network, a central office (CO) provides interactive communication between a service provider and a plurality of user terminals. To synchronize transmissions of the user terminals, a timebase timer in the CO generates modulo N-bit cyclical reference counts as time markers. In a downstream direction to the plurality of user terminals, time marker insertion units in the CO receive both (a) separate digital TDMA transport streams having a predetermined data rate including data packets and Media Access Control (MAC) packets that are interspersed between the data packets at predetermined intervals, and (b) the time markers generated by the timebase timer, and insert a currently received time marker count into a concurrently received MAC packet. The resultant downstream TDMA transport streams with the inserted time marker counts in the MAC packets are transmitted in continuous TDMA output transport stream to the remote user terminals. The time markers are independent of a data rate, a physical channel, and a channel protocol of the transport stream. In each user terminal, a network interface module synchronizes itself by comparing received time markers and locally generated time marker counts for correcting a local oscillator frequency. Upstream channel units in the CO are synchronized using the timebase timer generated time markers for receiving and processing upstream data packets upon arrival at their preassigned channel unit.
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Citations
21 Claims
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1. A time division multiple access (TDMA) communication network comprising:
channel synchronizing means for synchronizing channels in a downstream direction towards users of the communication network comprising; a timebase timer for generating time markers comprising modulo N-bit programmable cyclical reference counts that are incremented at a predetermined frequency and are reset to 0 when the reference counts reach a predefined value; and at least one time marker insertion unit, each time marker insertion unit comprising a first input terminal for receiving a digital TDMA transport stream having a predetermined data rate and comprising data packets and Media Access Control (MAC) packets that are interspersed between the data packets at predetermined intervals, a second input terminal for receiving the time markers generated by the timebase timer and for inserting a currently received time marker count into a currently received MAC packet, and an output terminal for transmitting the received TDMA data stream with the inserted time marker counts in the MAC packets in a continuous output TDMA transport stream to remote user terminals where the time markers are independent of a data rate, a physical channel, and a channel protocol of the transport stream and are used for synchronizing the user terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A time division multiple access (TDMA) communication network comprising:
channel synchronizing means for synchronizing channels in a down stream direction towards users of the communication network comprising; a timebase timer for generating time markers comprising modulo N-bit programmable cyclical reference counts that are incremented at a predetermined frequency and are reset to 0 when the reference counts reach a predefined value; and a plurality of time marker insertion units, each time marker insertion unit comprising; a first input terminal for receiving a digital TDMA transport stream having a predetermined data rate and comprising data packets and Media Access Control (MAC) packets that are interspersed between the data packets at predetermined intervals; a second input terminal for receiving the time markers generated by the timebase timer and for inserting a currently received time marker count into a currently received MAC packet; and an output terminal for transmitting the received TDMA data stream with the inserted time marker counts in the MAC packets in a continuous TDMA output transport stream to remote user terminals, where the time markers are independent of a data rate, a physical channel, and a channel protocol of the TDMA output transport stream and are used for synchronizing the user terminals, where two of the time marker insertion units receive digital TDMA transport streams having different predetermined data rates. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method of synchronizing communications between central office equipment and a plurality of remote user terminals in a TDMA communication network comprising the steps of:
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(a) generating a time marker sequence comprising modulo N-bit programmable cyclical reference counts that are incremented at a predetermined frequency in a timebase timer and are reset to 0 when the count reaches a predefined value; (b) receiving at least one digital time division multiple access (TDMA) transport stream, each digital TDMA transport stream comprising a predetermined frequency including data packets and Media Access Control (MAC) packets that are interspersed between the data packets at predetermined intervals; (c) inserting a currently received time marker count generated in step (a) into a MAC packet that is concurrently received in step (b) in each of the at least one digital TDMA transport streams in a time marker insertion unit; and (d) transmitting each digital TDMA transport stream with the inserted time marker counts in the MAC packets from step (c) in a separate continuous analog downstream TDMA transport stream to remote user terminals, where the time markers in each of the analog downstream TDMA output transport streams are independent of a data rate, a physical channel, and a channel protocol of the downstream TDMA output transport stream and are used by the plurality of user terminals for synchronizing their upstream data transmissions. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification