Optical/radio local access network

• US 7,295,777 B1
• Filed: 05/30/2006
• Issued: 11/13/2007
• Est. Priority Date: 08/17/2000
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Miller, Robert R., Britz, David M., Lin, Lih-Yuan, Dodley, Jeevan Prakash
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): WANG, QUAN ZHEN
• Application Number:
  US11/442,924
• Time in Patent Office: 532 Days
• Field of Search: 398/70, 398/83, 398/115, 398/118, 398119-131, 379 561- 563, 379/259
• US Class Current: 398/70
• CPC Class Codes: H04B 10/1125 using a single common optical path
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• 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 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04J 14/0307 Multiplexers; Demultiplexers
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]

Abstract

A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link, the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.

Claims

1. A communication system comprising:

a plurality of nodes, each node including an optical switch to controllably route signals from a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch;

a plurality of point-to-point links that interconnect the plurality of nodes into a network, each point-to-point link including a free space optical channel for likewise interconnecting the plurality of nodes, a first free space optical channel coupling to a first node through a receive path and to a second node through a transmit path, the receive path coupling to a respective out-port of the optical switch of the first node, the transmit path coupling to a respective in-port of the optical switch of the second node, further comprising a wireless network control system coupled to each node of the plurality nodes; and

a communication hub coupled to the network, the communication hub comprising

a plurality of neighborhood links associated with corresponding users in a one-to-one relationship;

an optical switch coupled to the plurality of neighborhood links;

a trunk coupled to the optical switch; and

a wireless network-controlled switch responsive to the wireless network control system to selectably couple the trunk between a free space optical channel link to the communication network and an optical fiber link to the communication network.

2. The communication system as defined in claim 1 wherein the communication hub trunk comprises

a wavelength division multiplexer coupled between the wireless network-controlled switch and the optical switch.

3. The communication system as defined in claim 1 wherein at least one neighborhood link of the plurality of communication hub neighborhood links comprises a free space optical channel telescope for communicating free space optical signals between the optical switch and the corresponding user.

4. The communication system as defined in claim 1 wherein at least one neighborhood link of the plurality of communication hub neighborhood links comprises

a length of optical fiber coupled at a first end to the output of the optical switch;

and

a free space optical telescope coupled to a second, opposing end of the length of optical fiber for communication signals between the optical fiber at a corresponding user.