SYSTEM AND METHOD FOR INTEROPERATING A RADIO-OVER-FIBER BASED NETWORK IN A FIBER-TO-THE-HOME NETWORK

• US 20150050026A1
• Filed: 08/19/2014
• Published: 02/19/2015
• Est. Priority Date: 08/19/2013
• Status: Active Grant

• Current Assignee: Telekom Malaysia Berhad
• Original Assignee: Telekom Malaysia Berhad
• Inventors: Samsuri, Norhakimah Md, Rasmi, Amiza, Kushairi, Norhapizin, Ismail, Mohd Azmi, Mohamad, Romli
• Granted Patent: US 9,419,715 B2
• Time in Patent Office: Days
• US Class Current: 398/116
• CPC Class Codes: H04B 10/25754 Star network topology
• CPC Class Codes: H04B 10/2589 Bidirectional transmission

Abstract

The present invention relates to a system for interoperating a full-duplex radio-over-fiber (RoF) network in a fiber-to-the-home (FTTH) network and to a method associated with the system. The system comprises, at the central station (100), a laser diode (105a), a first optical circulator (105b), an optical carrier generating unit (105c), and a second optical circulator (105d). The system comprises, at a base station (101), a third optical circulator (101a) a band pass filter (101b) coupled to the third optical circulator (101a) and configured to select only the optical signal having a corresponding pass band in which is used for converting an uplink signal as a remote local oscillator signal. The unselected optical signal is transmitted as downlink data.

Claims

1. A system for communication between a radio-over-fiber based network and a fiber-to-the-home network, comprising:

a central station (100); and

a base station (101) connected to the central station by an optical link (102);

characterized in that,

the central station (100), comprising;

a laser diode (105a) configured for generating a laser optical signal;

a first optical circulator (105b) coupled to the laser diode (105a) and configured to circulate the laser optical signal and a downlink optical signal received by the central station (100);

an optical carrier generating unit (105c) coupled to the first optical circulator (105b) configured to generate an optical carrier for each of the optical signals; and

a second optical circulator (105d) coupled to the optical carrier generating unit (105c) configured to circulate the optical signals and/or the optical carrier for transmission through the optical link (102);

the base station (101), comprising;

a third optical circulator (101a) optically connected to the optical link (102);

a band pass filter (101b) coupled to the third optical circulator (101a) and configured to select only the optical signal having a corresponding pass band in which is used for converting an uplink signal, wherein the unselected is transmitted as downlink data.

2. system according to claim 1 further comprising:

an optical line terminal (104) connected to the central station (100) and configured to transmit the downlink optical signal; and

an optical network unit (107) connected to the base station (101) and configured to transmit the uplink signal; and

an optical splitter (103) coupled to the optical link (102) and configured to divide the transmission in accordance with number of the base station (101).

3. A system according to claim 1, wherein the central station (100) further comprises a band pass filter (105e) disposed between the laser diode (105a) and the first optical circulator (105b) configured to allow only the laser optical signal to pass.

4. A system according to claim 1, wherein the base station (101) comprising:

a first photo detector (101c) coupled to the band pass filter (101b) and configured for converting the laser optical signal to a laser electrical signal;

a low noise electrical amplifier (101d) coupled to the first photo detector (101c) and being configured to amplify the laser electrical signal;

an electrical mixer (101e) connected to the low noise amplifier (101d) and configured for mixing the uplink signal and the laser electrical signal and for converting the uplink signal to an intermediate frequency; and

a modulator (101f) for converting the intermediate frequency to an uplink optical signal in which is inputted to the third optical circulator (101a).

5. A system according to claim 4, wherein the modulator (101f) is a laser diode configured for direct modulation.

6. A system according to claim 1, wherein the base station (101) comprising:

a second photo detector (101g) coupled to the third optical circulator (101a) and configured to convert the downlink optical signal to a downlink electrical signal; and

a power amplifier (101h) to receive and amplify the downlink electrical signal.

7. A system according to claim 1, wherein the base station (101) further comprising:

a plurality of electrical filters (101i);

an electrical diplexer (101j); and

an antenna (101k).

8. A system according to claim 1, wherein the optical carrier generating unit (105c) comprising:

a polarization controller (105c-1) configured to adjust polarization state of the laser optical signal and the downlink optical signal;

a Mach-Zender modulator (105c-2) coupled to the polarization controller (105c-1) and configured to modulate the laser optical signal and the downlink optical signal with a local oscillator signal provided by a local oscillator (105c-3).

9. A system according to claim 1, wherein the optical carrier generating unit (105c) further comprising:

a power splitter (105c-4) connected to the local oscillator (105c-3) for dividing the local oscillator signal to a ratio of 1;

2;

a phase shifter (105c-5) coupled to the power splitter (105c-4) for phase-shifting the laser optical signal and the downlink optical signal; and

a broadband optical amplifier (105c-6) coupled to the Mach-Zender modulator (105c-2) and configured to optically amplify the resulting optical signals.

10. A system according to claim 1 further comprises a premise equipment (106).

11. A system according to claim 1, wherein the laser optical signal and the downlink optical signal have different wavelengths.

12. A system according to claim 1, wherein the first optical circulator (105b) is a four-port optical circulator.

13. A system according to claim 1, wherein the second optical circulator (105d) is a three-port optical circulator.

14. A system according to claim 1, wherein the third optical circulator (101a) is a four-port optical circulator.

15. A method of operating a radio-over-fiber based network in a fiber-to-the-home network, characterized in that, the method comprising the steps of:

receiving a downlink optical signal;

providing a laser optical signal at a wavelength different than that of the downlink optical signal;

generating an optical carrier for each of the optical signals;

converting an uplink signal to an intermediate frequency using the laser optical signal; and

transmitting the downlink optical signal.

16. A method according to claim 15 further comprising the steps of:

filtering the optical signals;

adjusting polarization states of the optical signals;

providing a local oscillator signal;

s phase-shifting the optical signals;

modulating the optical signals with the local oscillator signal; and

amplifying the resulting optical signals.

17. A method according to claim 16 including splitting the local oscillator signal to two channels at a ratio of 1:

2.

18. A method according to claim 15 further comprising the steps of:

converting the laser optical signal to a laser electrical signal;

filtering and amplifying the laser electrical signal;

mixing the laser electrical signal with the uplink signal; and

converting the intermediate frequency to an uplink optical signal.

19. A method according to claim 15 further comprising the steps of:

converting the downlink optical signal to a downlink electrical signal;

filtering the downlink electrical signal; and

amplifying the downlink electrical signal.