Fiber optic telephone loop network

• US 5,325,223 A
• Filed: 12/19/1991
• Issued: 06/28/1994
• Est. Priority Date: 12/19/1991
• Status: Expired due to Term

• Current Assignee: Rockstar Consortium US LP (Rockstar Consortium Inc.)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Bears, James A.
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/810,067
• Time in Patent Office: 922 Days
• Field of Search: 359/118, 359/119, 359/121, 359/126, 359/137, 359/125, 359/117, 358/84, 358/86, 455/3.1, 455/4.1, 455/4.2, 455/5.1
• US Class Current: 398/100
• CPC Class Codes: H04Q 11/0001 using optical switching
• CPC Class Codes: H04Q 2011/0081 Fault tolerance; Redundancy; Recovery; Reconfigurability

Abstract

Novel fiber optic telephone loop networks are disclosed. In the networks, single mode fiber optics are used for feeder and distribution segments of the loop but multimode fiber optics are used for the drops. The use of the multimode fiber optics has permitted the use of less costly optoelectronic devices. Surface light emitting diodes are such economical but reliable parts. Fiber service terminals located near customer homes convert single mode operation to the multimode operation. The networks are relatively easy to install and upgrade and are very economically competitive with other known FTTC and FTTH schemes.

Claims

1. A cost optimized digital telephone loop network connecting a switch in a central switching office and a plurality of individual homes, comprising:

a remote fiber terminal located at said central switching office and including multiplexer/demultiplexer means for converting electrical signals from the switch into multiplexed digital optical signals and vice versa;

between one to sixteen fiber service terminal means, each located substantially near a group of said plurality of homes, each of said fiber service terminal means including multiplexer/demultiplexer means for converting said multiplexed optical signals into demultiplexed individual optical home signals and vice versa and a plurality of surface light emitting diodes for transmitting said individual optical signal to and from said plurality of homes;

single mode fiber optic feeder cables connecting said remote terminal and plurality of fiber service terminal means for transmitting said multiplexed optical signals into said fiber service terminal means;

a small number of passive optical splitter/combiner means on any of the single mode fiber optic feeder cables for splitting and combining said multiplexed optical signals to and from said plurality of fiber service terminal means, the split rate of each splitter/combiner means being less than one-to-four;

a plurality of pairs of multimode fiber optic drops, each pair optically connecting one of said plurality of fiber service terminal means and one individual home of said plurality of homes, by way of said plurality of surface light emitting diodes, one drop within each pair being for transmitting said demultiplexed individual home optical signal to said individual home and the other drop of the pair being for receiving individual home optical signal from said individual home;

house optical terminal means, each located at said individual home and including an individual line card which contains a surface light emitting diode for converting said demultiplexed individual home optical signal into a home electrical signal and vice versa, and

electrical drops, each connecting a fiber service terminal means and said individual home for supplying the electrical power to its house optical terminal means.

2. The cost optimized digital telephone loop network connecting a switch in a central switching office and a plurality of individual homes, according to claim 1, further comprising a plurality of power pedestals, each located near said fiber service terminal means and connected to commercial electricity supply network for supplying the electrical power to said fiber service terminal means and including an emergency battery means.