Optical distributed antenna system

• US 8,606,110 B2
• Filed: 01/08/2012
• Issued: 12/10/2013
• Est. Priority Date: 01/08/2012
• Status: Active Grant

• Current Assignee: Optiway Limited
• Original Assignee: Optiway Limited
• Inventors: Rospsha, Nimrod, Ben Ezra, Yossef
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US13/345,723
• Publication Number:
  US 20130177317A1
• Time in Patent Office: 702 Days
• Field of Search: 398115-117
• US Class Current: 398/116
• CPC Class Codes: H04B 10/25754 Star network topology
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 2014/0253 Allocation of downstream wavelengths for upstream transmission

Abstract

Optical distributed antenna systems comprising a head-end unit adapted to transmit downlink a modulated optical signal with wavelength λ₀ and N un-modulated optical signals with wavelength λ_N and N remote units (RU) and including at least one circulator. In some embodiments, an HE unit includes an arrangement of a single circulator coupled to a single detector, the arrangement preventing beating. In some embodiments, a RU includes a reflective electro-absorption transceiver (REAT) which includes a single optical interface and a single RF port. The REAT detects the optical signal with λ₀ and converts it into a RF signal, and reflects an un-modulated optical signal with wavelength λ_N to provide a modulated uplink optical signal. In some embodiments, a RU is configured as an optical antenna unit. In some embodiments, a plurality of RUs is combined with passive optical distribution units to provide hierarchical DAS architectures.

Claims

1. An optical distributed antenna system (DAS) comprising:

a) a head-end (HE) unit used to transmit downlink (DL) a modulated DL λ

₀ optical signal and a plurality N of continuous waves (CWs), each CW having a different wavelength λ

_N; and

b) a plurality of remote units (RU), wherein each RU includes a reflective electro-absorption transceiver (REAT) which has a single optical interface and a single RF port, the REAT used to detect and convert the λ

₀ optical signal into a RF signal and to reflect and modulate one CW with wavelength λ

_N for uplink transmission to the HE unit.

2. The optical DAS of claim 1, wherein the HE unit includes one optical transmitter which provides the λ

₀ optical signal and N optical transmitters which provide the CWs with wavelengths λ

_N.

3. The optical DAS of claim 1, wherein the REAT includes a multi-quantum well structure.

4. The optical DAS of claim 1, wherein the HE unit is connected to each RU by a single mode optical fiber.

5. The optical DAS of claim 1, wherein at least one RU is connected to a passive DAS.

6. The optical DAS of claim 1, wherein at least one RU is configured as an optical antenna unit.

7. The optical DAS of claim 1, adapted to convert digital to RF signals and RF to digital signals and to transmit digital signals both uplink and downlink.

8. The optical DAS of claim 2, wherein the HE unit includes a 1×

M splitter for splitting the λ

₀ optical signal to M optical interfaces and N wavelength division multiplexers (WDM), each WDM configured to receive the λ

₀ optical signal and a λ

_N CW and to output both to a respective RU.

9. The optical DAS of claim 8, wherein the HE unit further includes N optical circulators positioned between N optical transmitters which route the CWs with wavelengths λ

_N to the N WDMs.

10. The optical DAS of claim 1, wherein the HE unit includes a 1×

N C/DWDM combiner for combining the N un-modulated optical signals into a single output.

11. The optical DAS of claim 1, further comprising a passive optical antenna unit (PODU) interposed between a RU and the HE unit, the PODU configured to enable a hierarchical DAS architecture.

12. The optical DAS of claim 6, further including a passive optical antenna unit (PODU) interposed between an optical antenna unit and the HE unit, the PODU configured to enable a hierarchical DAS architecture.

13. The optical DAS of claim 1, wherein the HE unit includes a single detector and a circulator of uplink signals with wavelength λ

₁ to λ

_N which prevents beating.

14. An optical distributed antenna system (DAS) comprising:

a) a head-end (HE) unit used to transmit downlink a modulated λ

₀ optical signal and a plurality N of continuous waves (CWs) with respectively different wavelengths λ

_N, the HE unit including an arrangement of a single detector and a circulator for a bunch of uplink signals with wavelength λ

₁ to λ

_N, wherein the arrangement prevents beating per bunch; and

b) a plurality of remote units (RU), each RU including a reflective electro-absorption transceiver (REAT) used to detect and convert the λ

₀ optical signal into a RF signal and to reflect and modulate one CW with wavelength λ

_N for uplink transmission to the HE unit.

15. The optical DAS of claim 14, further comprising:

c) a passive optical antenna unit (PODU) interposed between at least one RU and the HE unit, the PODU configured to enable a hierarchical DAS architecture.

16. The optical DAS of claim 14, wherein the REAT includes a single optical interface and a single RF port.

17. The optical DAS of claim 14, adapted to convert digital to RF signals and RF to digital signals and to transmit digital signals both uplink and downlink.

18. The optical DAS of claim 14, wherein the REAT includes a multi-quantum well structure.

20. The method of claim 18, further comprising the step of:

d) performing digital to RF conversion in both uplink and downlink, thereby adapting the optical DAS for digital data transmission.

19. A method for communications in an optical distributed antenna system (DAS) comprising the steps of:

a) at a head-end (HE) unit, transmitting downlink to a remote unit (RU) a modulated optical signal with wavelength λ

₀ and a continuous wave (CW) with wavelength λ

_N;

b) at the RU, using a reflective electro-absorption transceiver (REAT) with a single optical interface and a single RF port to convert the modulated optical signal with wavelength λ

₀ into a downlink RF signal and to reflect and modulate the CW with wavelength λ

_N to obtain a reflected modulated optical signal with wavelength λ

_N; and

c) transmitting the reflected optical signal with wavelength λ

_N uplink to the HE unit.