Asymmetrical PON with Multiple Return Channels

• US 20080037990A1
• Filed: 02/21/2007
• Published: 02/14/2008
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Effenberger, Frank J.
• Granted Patent: US 8,050,561 B2
• Time in Patent Office: Days
• US Class Current: 398/67
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• 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: 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 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
• CPC Class Codes: H04Q 2011/0064 Arbitration, scheduling or medium access control aspects

Abstract

A passive optical network (PON) system comprising a plurality of optical network units (ONUs) having one downstream receiver and one upstream transmitter, an optical line terminal (OLT) having a downstream transmitter and a plurality of upstream receivers, wherein each upstream receiver is associated with a subset of the ONUs, and an optical distribution network (ODN) that connects the OLT to the ONUs is disclosed. An OLT for a PON, comprising a downstream transmitter, and a plurality of upstream receivers, wherein a downstream transmitter bandwidth is greater than each upstream receiver bandwidth is also disclosed. A network component comprising a processor configured to implement a method comprising determining a downstream bandwidth and an upstream bandwidth for a PON, and increasing a number of upstream channels per downstream channel for the PON when asymmetry between the downstream bandwidth and the upstream bandwidth is greater than a threshold amount is also disclosed.

Claims

1. A passive optical network (PON) system comprising:

a plurality of optical network units (ONUs) having one downstream receiver and one upstream transmitter;

an optical line terminal (OLT) having a downstream transmitter and a plurality of upstream receivers, wherein each upstream receiver is associated with a subset of the ONUs; and

an optical distribution network (ODN) that connects the OLT to the ONUs.

2. The system of claim 1 wherein the downstream transmitter broadcasts data to all of the ONUs, and wherein each upstream receiver receives data from a different subset of the ONUs.

3. The system of claim 1 wherein the ONUs share a downstream wavelength and an upstream wavelength, and wherein each subset of the ONUs is associated with a separate optical cable in the ODN.

4. The system of claim 1 wherein all ONUs share a downstream wavelength, and wherein each subset of the ONUs is associated with a different upstream wavelength.

5. The system of claim 4 wherein the ONUs share at least one optical cable in the ODN.

6. The system of claim 1 wherein the number of upstream receivers is selectively changed over time to adjust the bandwidth symmetry between upstream and downstream communications.

7. The system of claim 1 wherein the OLT further comprises a splitter located between the downstream transmitter and the ONUs, wherein outputs of the splitter are forwarded to different subsets of the ONUs.

8. The system of claim 1 wherein the ODN comprises a splitter, wherein the outputs of the splitter are forwarded to a single subset of ONUs.

9. The system of claim 1 wherein power for the downstream transmitter is selectively determined based on the number of upstream receivers.

10. An optical line terminal (OLT) for a passive optical network (PON), comprising:

a downstream transmitter; and

a plurality of upstream receivers, wherein a downstream transmitter bandwidth is greater than each upstream receiver bandwidth.

11. The OLT of claim 10 further comprising a splitter configured to split a signal from the downstream transmitter based on the number of upstream receivers.

12. The OLT of claim 11 further comprising a plurality of diplexers located downstream of the splitter, wherein the number of diplexers is based on the number of upstream receivers.

13. The OLT of claim 10 further comprising a wavelength division multiplexer configured to support different wavelengths based on the number of upstream receivers.

14. The OLT of claim 13 further comprising a diplexer located between the downstream transmitter and the wavelength division multiplexer.

15. The OLT of claim 10 wherein the number of upstream receivers is variable over time to adjust bandwidth symmetry between upstream and downstream communications.

16. The OLT of claim 10 wherein power for the downstream transmitter is selectively determined based on the number of upstream receivers.

17. A network component comprising a processor configured to implement a method comprising:

determining a downstream bandwidth and an upstream bandwidth for a passive optical network (PON); and

increasing a number of upstream channels per downstream channel for the PON when asymmetry between the downstream bandwidth and the upstream bandwidth is greater than a threshold amount.

18. The method of claim 17 wherein increasing a number of upstream channels per downstream channel for the PON comprises replacing a first optical line terminal (OLT) in the PON with a second OLT, the second OLT having more upstream receivers than the first OLT.

19. The method of claim 17 wherein increasing a number of upstream channels per downstream channel for the PON comprises replacing multiple optical line terminals (OLTs) in the PON with an adjustable OLT, the adjustable OLT having a plurality of upstream receivers and a single downstream transmitter.

20. The method of claim 17 further comprising dividing a plurality of optical network units (ONUs) into subsets and assigning each subset to a separate upstream channel.