Distributed termination system for two-way hybrid networks

• US 6,490,727 B1
• Filed: 10/07/1999
• Issued: 12/03/2002
• Est. Priority Date: 10/07/1999
• Status: Expired due to Term

• Current Assignee: Harmonic Incorporated
• Original Assignee: Harmonic Incorporated
• Inventors: Piehler, David, Bonen, Adi, Kepten, Ilan, Nazarathy, Moshe
• Primary Examiner(s): Faile, Andrew
• Assistant Examiner(s): Srivastava, Vivek
• Application Number:
  US09/414,979
• Time in Patent Office: 1,153 Days
• Field of Search: H04/N.7173, H04/N.716, 725/121, 725/122, 725/126, 725/129, 725/98, 725/118, 725/119, 725/148, 725/111, 725/105
• US Class Current: 725/129
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0252 Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04N 21/44245 Monitoring the upstream path of the transmission network, e.g. its availability, bandwidth
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission

Abstract

In hybrid fiber coaxial cable networks such as used in cable television where two-way digital communications are desired, a distributed termination system is provided. In such a system the home terminals are digital terminals, such as digital set-top boxes or cable modems using bi-directional transmission standards. The functionality of the head end controller in a conventional system is in this system distributed between the head end and the fiber nodes which link the coaxial cable and optical fiber portions of the system. Thereby the upstream detection takes place in the fiber nodes rather than in the head end by placing upstream burst receivers in the fiber nodes. Further there is a distributed method to enable this by providing synchronization and calibration control between the head end and the fiber nodes. Also, the return path is a digital return path supported by having the burst receivers located in the fiber nodes.

Claims

1. A network comprising:

a head-end;

at least one node coupled to the head-end by an optical fiber network;

at least one terminal coupled to the node by other than optical fiber, there being a return path via the node from the terminal to the head-end, the node including;

an optical receiver coupled between the optical fiber network and the terminal to carry signals from the head-end to the terminal; and

in the return path, at least one optical transmitter coupled to the optical fiber network; and

at least one burst receiver coupled between the optical transmitter and the terminal;

further comprising a hub apparatus coupled between the node and the head-end in the optical fiber network, the hub apparatus comprising;

a plurality of optical receivers, each optical receiver being coupled to an associated node;

a multiplexer having each of its input terminals coupled to an output terminal of one of the optical receivers;

an optical transmitter coupled between an output terminal of the multiplexer and the head-end; and

wherein the hub apparatus further comprises an envelope detector coupled between each optical receiver and the associated multiplexer input terminal.

2. The network of claim 1, wherein the hub apparatus further comprises:

a second optical transmitter coupled to the optical fiber network; and

a bandpass filter coupled between the second optical transmitter and the nodes.

3. The network of claim 1, further comprising at least one additional hub apparatus coupled in the optical fiber network between the head-end and the node, the additional hub apparatus being coupled to a plurality of nodes and comprising:

a multiplexer having a plurality of input ports each coupled to one of the hub apparatuses; and

an optical amplifier coupled between the head-end and the nodes.

4. A network comprising:

a head-end;

at least one node coupled to the head-end by an optical fiber network;

at least one terminal coupled to the node by other than optical fiber, there being a return path via the node from the terminal to the head-end, the node including;

an optical receiver coupled between the optical fiber network and the terminal to carry signals from the head-end to the terminal; and

in the return path, at least one optical transmitter coupled to the optical fiber network; and

at least one burst receiver coupled between the optical transmitter and the terminal;

further comprising a hub apparatus coupled between the node and the head-end in the optical fiber network, the hub apparatus comprising;

a plurality of optical receivers, each optical receiver being coupled to an associated node;

a multiplexer having each of its input terminals coupled to an output terminal of one of the optical receivers; and

an optical transmitter coupled between an output terminal of the multiplexer and the head-end;

wherein the hub apparatus further comprises;

a summer coupled to an output terminal of each of the optical receivers; and

a plurality of demodulators coupled to the summer, wherein an output terminal of each of the demodulators is coupled to an input terminal of the multiplexer.

5. A hub apparatus for a network having a head-end coupled by an optical fiber network to the hub apparatus, the hub apparatus being coupled by optical fiber to a plurality of nodes, the hub apparatus comprising:

a plurality of optical receivers, each optical receiver being coupled to an associated one of the nodes;

a first multiplexer having each of its input terminals coupled to an output terminal of one of the optical receivers;

an output terminal coupled between an output terminal of the multiplexer and the optical fiber network;

an additional optical receiver coupled to the optical fiber network;

a demodulator coupled to the additional optical receiver;

a plurality of burst receivers, each coupled to one of the optical receivers;

interface circuitry coupled between the demodulator and a control terminal of each of the burst receivers; and

a second multiplexer having each of its input terminals coupled to one of the burst receivers and its output terminal coupled to the first multiplexer.