US5719872A
Expired / Lapsed
US
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Reverse path allocation and contention resolution scheme for a broadband communications system
Assignee: Cisco Technology Inc
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Filing: 1996-11-27
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Granted: 1998-02-17
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Expires: 2016-11-27
Abstract
Abstract A broadband communications system for coupling telephony or other digital networks to a CATV network. The system transmits a multiplex of telephony signals in the forward band of the CATV network. The forward telephony channels are demodulated and demultiplexed by a plurality of subscriber terminals into the individual telephony signals directed to an addressed subscriber. Signals returning from subscribers are digitized into standard telephony signals onto the reverse band of the CATV network, and demodulated and multiplexed into a standard telephony signal that is interfaced to the telephony network. A multiplicity of subscribers are initially assigned to a selected reverse band channel. If more than one subscriber contends for use of the reverse channel by transmitting in the channel, signals from the contending subscribers interfere and prevent any subscriber's identity from being decoded and acknowledged. The contending subscribers wait for a random wait time and re-attempt to transmit. Upon transmission re-attempt, one of the subscribers (typically the one with the shortest wait time) will successfully gain access to the reverse channel, and the other subscribers are assigned to a different reverse channel.
Inventors
- 👤 Gregory Thomas Dubberly
- 👤 Thomas Autrey Bohannon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:47
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04H; H04H20/00; H04H20/65; H04H20/76; H04H20/77; H04H20/78; H04H20/79; H04H20/81; H04H60/00; H04H60/76; H04H60/81; H04H60/93; H04H60/94; H04H60/96; H04H60/97; H04J; H04J1/00; H04J1/02; H04J1/12; H04J3/00; H04J3/16; H04J3/1605; H04J3/1623; H04L12/2801; H04M; H04M7/00; H04M7/006; H04N; H04N7/00; H04N7/10; H04N7/14; H04N7/16; H04N7/173; H04N7/17309; H04J2203/00; H04J2203/0001; H04J2203/0028; H04J2203/0039; H04J2203/0041; H04J2203/0089; H04L12/40; H04L12/407; H04L12/413; H04N2007/1739; H04Q2213/00; H04Q2213/13332
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
173 words
A telephony system for communicating telephony signals between a telephony network and a broadband communication network including a headend communicating to a plurality of subscribers, comprising: a modulator, coupled between the telephony network and the headend, for modulating the telephony signals from the telephony network on a carrier in a first band of the broadband communication network; more than one subscriber terminal with a frequency agile modulator for modulating telephony signals from the subscriber in a selected frequency subband in a second band of the broadband network for communication to the headend; equipment for assigning a plurality of subscribers to a selected frequency subband in the second band of a subscription network; reverse path contention resolution equipment for detecting contention by more than one subscriber for the selected frequency subband and reassigning at least one subscriber to a different frequency subband in the second band; and a demodulator, coupled between the telephony network and the headend, for demodulating the telephony signals in the selected frequency subband and coupling them to the telephony network.
Claim 2
Dependent Claim
173 words
A telephony system for communicating telephony signals between a telephony network and a broadband communication network including a headend communicating to a plurality of subscribers, comprising: a modulator, coupled between the telephony network and the headend, for modulating the telephony signals from the telephony network on a carrier in a first band of the broadband communication network; more than one subscriber terminal with a frequency agile modulator for modulating telephony signals from the subscriber in a selected frequency subband in a second band of the broadband network for communication to the headend; equipment for assigning a plurality of subscribers to a selected frequency subband in the second band of a subscription network; reverse path contention resolution equipment for detecting contention by more than one subscriber for the selected frequency subband and reassigning at least one subscriber to a different frequency subband in the second band; and a demodulator, coupled between the telephony network and the headend, for demodulating the telephony signals in the selected frequency subband and coupling them to the telephony network.
Claim 3
Dependent Claim
32 words
The system of claim 1, wherein the subscriber terminal includes a subscriber terminal demodulator for demodulating the telephony signals in the first band of broadband network and coupling them to the subscriber.
Claim 4
Dependent Claim
84 words
The system of claim 2, further comprising: a noise monitor for monitoring the noise level in a selected frequency subband associated with a particular subscriber, and equipment responsive to the noise monitor for communicating a frequency change signal to said particular subscriber when the noise level in the selected frequency subband exceeds a predetermined threshold, whereby the subscriber terminal changes the frequency for communicating at least some of the telephony signals to a different selected frequency subband when a given channel becomes too noisy.
Claim 5
Dependent Claim
33 words
The system of claim 1, wherein the broadband communication network is a cable television (CATV) network, and further comprising equipment for providing television program signals in said first band of frequencies to subscribers.
Claim 6
Dependent Claim
41 words
The system of claim 1 wherein the assigning equipment comprises: equipment for communicating a channel assignment message containing subscriber identification information and the identity of one or more selected frequency subbands in the second band associated with the subscriber identification information.
Claim 7
Dependent Claim
20 words
The system of claim 5, wherein said channel assignment message is transmitted in a directory channel in the first band.
Claim 8
Dependent Claim
45 words
The system of claim 1, wherein the frequency agile modulator is operative to change the frequency at which telephony signals are being communicated to the headend from a first frequency subband to a second frequency subband in response to a command received from the headend.
Claim 9
Dependent Claim
51 words
The system of claim 7, wherein the frequency agile modulator comprises a quadrature phase shift keying (QPSK) modulator operative at selectable carrier frequencies varying in discrete increments of 128 kHz channels, beginning at a nominal initial carder frequency of 5.12 MHz, with a nominal data rate of 144 kbps per channel.
Claim 10
Dependent Claim
32 words
The system of claim 8, wherein each said 144 kbps channel comprises two 64 kbps DS0 telephony channels and one 16 kbps overhead channel including data headers, address information, and CRC data.
Claim 11
Dependent Claim
23 words
The system of claim 8, wherein each 128 kHz channel comprises a 108 kHz bandwidth data channel and 20 kHz in guard bands.
Claim 12
Dependent Claim
45 words
The system of claim 1, further comprising: a customer interface unit including a demodulator for demodulating said telephony signals in said first frequency band to obtain an incoming telephony signal directed to a particular subscriber and coupling said incoming telephony signal to a telephony port.
Claim 13
Dependent Claim
19 words
The system of claim 11, wherein said telephony signals are communicated to the customer interface unit via QPR modulation.
Claim 14
Dependent Claim
46 words
The system of claim 11, wherein said telephony signals communicated in the first frequency band comprise: a plurality of incoming telephony signals arranged in a plurality of channels; at least one directory channel containing channel assignment information; and at least one signaling channel containing status information.
Claim 15
Dependent Claim
39 words
The system of claim 13, wherein said telephony signals comprise a 3.168 MHz QPR modulated signaling containing 96 DS0 digital incoming telephony signals, said directory channel, said signaling channel, and CRC data associated with a frame of digital signals.
Claim 16
Dependent Claim
73 words
The system of claim 1, wherein a subscriber terminal is operative, in response to an outgoing call by a subscriber associated with the terminal, to begin transmitting signals in the selected frequency subband assigned by the assigning equipment as an initial transmission; and in response to failure to receive an acknowledge signal from the headend within a predetermined time period after said initial transmission, to cease transmitting signals in the selected frequency subband.
Claim 17
Dependent Claim
38 words
The system of claim 15, wherein the headend in responsive to said initial transmission from a particular subscriber for reassigning all other subscribers assigned to the selected frequency subband to a different frequency subband in the second band.
Claim 18
Dependent Claim
41 words
The system of claim 15, wherein the headend is operative for changing the frequency of a selected subscriber from the selected frequency subband in the second frequency band on the broadband communication network to another frequency subband during a communication session.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-02-16 | 2001-08-18 | 2002-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-02-16 | 2005-08-18 | 2006-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-02-16 | 2009-08-18 | 2010-02-17 | $7700.00 | Window Closed / Lapsed |