Passive optical network system supporting wireless communication

• US 8,270,833 B2
• Filed: 07/16/2009
• Issued: 09/18/2012
• Est. Priority Date: 03/20/2009
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Lin, Yu-Min, Tien, Po-Lung, Yuang, Maria C.
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US12/504,322
• Publication Number:
  US 20100239253A1
• Time in Patent Office: 1,160 Days
• Field of Search: 398 66- 73, 398115-117
• US Class Current: 398/72
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• 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 14/0265 Multiplex arrangements in bidirectional systems, e.g. interleaved allocation of wavelengths or allocation of wavelength groups
• CPC Class Codes: H04J 14/0275 using an optical service channel
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 2014/0253 Allocation of downstream wavelengths for upstream transmission
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A passive optical network (PON) system supporting wireless communication includes an optical line terminal (OLT) configured on a central office, an optical distribution network (ODN), and a plurality of optical network units (ONUs) respectively configured on user ends. The ODN is connected to the OLT and the ONUs in a one-to-many manner. The OLT sends a downstream optical signal to the ODN, and receives an upstream optical signal. The ODN circularly guides the optical signal to each ONU. Each ONU receives and reflects the downstream optical signal, processes the received downstream optical signal, receives and processes the upstream optical signal, carries an electrical signal to be uploaded into the upstream optical signal, and carries data received by a remote antenna into the upstream optical signal. Through the above architecture, the PON system supports wireless communication.

Claims

1. A passive optical network (PON) system supporting wireless communication, comprising:

an optical line terminal (OLT), for sending a downstream optical signal and receiving an upstream optical signal;

an optical distribution network (ODN), having an optical circulator assembly and first, second, . . . n^th optical fibers, wherein n is a positive integer greater than 2, the optical fibers are connected to the optical circulator assembly in sequence, the first optical fiber is connected to the OLT and transmits the downstream optical signal and the upstream optical signal, and the optical circulator assembly guides the optical signals from a i^th optical fiber to a (i+1)^th optical fiber, i is a positive integer and i<

n ; and

a plurality of optical network units (ONUs), connected to the second, . . . n^th optical fibers respectively, wherein each of the ONUs receives the optical signals from the corresponding second, . . . n^th optical fiber, generates the upstream optical signal, and then transmits the upstream optical signal back to the corresponding second, . . . n^th optical fiber;

each of the ONUs corresponding to the second, . . . (n−

1)^th optical fiber processes the received downstream optical signal and transmits the processed downstream optical signal back to the corresponding second, . . . (n−

1)^th optical fiber;

at least one of the ONUs is configured with a remote antenna, and the ONU configured with the remote antenna combines data received by the remote antenna with the upstream optical signal,

wherein the ONU corresponding to the second optical fiber comprises an upstream transmitter for converting an electrical signal to be uploaded to generate the upstream optical signal and transmitting the upstream optical signal back to the second optical fiber; and

wherein each of the ONUs respectively connected to the third, . . . n^th optical fiber comprises an upstream receiver and an upstream transmitter;

the upstream receiver receives and converts the upstream optical signal into a received electrical signal; and

the upstream transmitter combines an electrical signal to be uploaded with the received electrical signal to generate the upstream optical signal, and transmits the upstream optical signal back to the corresponding second, . . . n^th optical fiber.

2. The PON system according to claim 1, wherein a wavelength of the upstream optical signal is different from that of the downstream optical signal.

3. The PON system according to claim 2, wherein each of the ONUs comprises a coarse wavelength division multiplexer (CWDM) for splitting the received optical signals into the upstream optical signal and the downstream optical signal.

4. The PON system according to claim 3, wherein each of the ONUs comprises an optical switch and a first reflecting mirror;

the optical switch receives the optical signals;

upon being powered on, the optical switch guides the optical signals to the CWDM;

upon being powered off, the optical switch guides the optical signals to the first reflecting mirror;

the first reflecting mirror reflects the optical signals back to the optical switch, and the optical switch then guides the optical signals back to the second, . . . n^th optical fiber corresponding to the ONU.

5. The PON system according to claim 3, wherein each of the ONUs comprises a first optical coupler, a second reflecting mirror, and a downstream receiver;

the first optical coupler receives the downstream optical signal and splits the downstream optical signal to the second reflecting mirror and the downstream receiver;

the second reflecting mirror reflects the downstream optical signal from the first optical coupler back to the first optical coupler; and

the downstream receiver performs a decoding process on the downstream optical signal.

6. The PON system according to claim 3, wherein each of the ONUs comprises a first optical coupler, a fiber grating filter, and a downstream receiver;

the first optical coupler receives the downstream optical signal and splits the downstream optical signal to the fiber grating filter and the downstream receiver;

the fiber grating filter reflects the downstream optical signal from the first optical coupler back to the first optical coupler; and

the downstream receiver performs a decoding process on the downstream optical signal.

7. The PON system according to claim 1, wherein the upstream transmitter of the ONU configured with the remote antenna combines the data received by the remote antenna with the electrical signal to be uploaded and the received electrical signal to generate the upstream optical signal, and transmits the upstream optical signal back to the corresponding second, . . . n^th optical fiber.

8. The PON system according to claim 1, wherein each of the ONUs further comprises a second optical coupler having two splitting ends and one combining end;

the combining end receives the upstream optical signal from the corresponding optical fiber; and

the two splitting ends are respectively connected to the upstream receiver and the upstream transmitter.

9. The PON system according to claim 1, wherein each of the ONUs comprises:

a photoelectric converting element, for converting the upstream optical signal from the corresponding optical fiber into a first electrical signal;

a power splitter, for splitting the first electrical signal into a second electrical signal and a third electrical signal;

a digital processing controller, for receiving the second electrical signal, and combining the second electrical signal with an electrical signal to be uploaded to output a fourth electrical signal;

a first band pass filter, for filtering the third electrical signal to enable the third electrical signal within a predetermined frequency band range to pass through, so as to form a fifth electrical signal;

an electrical coupler, for coupling the fourth electrical signal with the fifth electrical signal to form a sixth electrical signal; and

an electro-optical converting element, for converting the sixth electrical signal into the upstream optical signal.

10. The PON system according to claim 9, wherein each of the ONUs further comprises a band stop filter for performing a band stop on the second electrical signal and then outputting the second electrical signal to the digital processing controller.

11. The PON system according to claim 10, wherein the band stop filter performs the band stop on the second electrical signal within the predetermined frequency band, and then outputs the second electrical signal.

12. The PON system according to claim 9, wherein the ONU configured with the remote antenna further comprises:

a frequency shifter, for performing a frequency shift on the data received by the remote antenna;

a second band pass filter, for filtering the frequency-shifted data to enable the frequency-shifted data within the predetermined frequency band range to pass through, so as to form a seventh electrical signal; and

a combiner, for combining the fifth electrical signal with the seventh electrical signal to form an eighth electrical signal, wherein the electrical coupler couples the eighth electrical signal with the fourth electrical signal to form the sixth electrical signal.

13. The PON system according to claim 9, wherein the electrical coupler is a directional coupler.

14. The PON system according to claim 9, wherein the photoelectric converting element is a photo sensor.

15. The PON system according to claim 9, wherein the digital processing controller comprises:

an analog to digital converter, for converting the second electrical signal into a digital signal;

an orthogonal frequency division multiplexing (OFDM) demodulator, for demodulating the digital signal into a demodulated signal;

a data access controller, for combining the demodulated signal with the electrical signal to be uploaded;

an OFDM modulator, for performing an orthogonal modulation on a combined signal; and

a digital to analog converter, for converting a modulated signal into an analog signal to output the analog signal as the fourth electrical signal.

16. The PON system according to claim 1, wherein the optical circulator assembly comprises first, second, . . . n^th circulators and n optical guides;

the first, second, . . . n^th circulators are ring jointed with each other by the n optical guides;

outer sides of the first, second, . . . n^th circulators are correspondingly opto-connected to the first, second, . . . n^th optical fibers respectively; and

each circulator guides the optical signals from one of opto-connections to the next opto-connection.

17. A passive optical network (PON) system supporting wireless communication, comprising:

an optical line terminal (OLT), for sending a downstream optical signal and receiving an upstream optical signal;

an optical distribution network (ODN), having an optical circulator assembly and n optical fibers, wherein n is a positive integer greater than 2, the optical fibers are connected to the optical circulator assembly in sequence, and the first optical fiber is connected to the OLT and transmits the downstream optical signal and the upstream optical signal; and

a plurality of optical network units (ONUs), connected to the second, . . . n^th optical fibers respectively, wherein each of the ONUs receives and processes the optical signals from the optical fiber correspondingly connected to the ONU, generates the upstream optical signal, and then transmits the upstream optical signal back to the corresponding second, . . . n^th optical fiber; and

at least one of the ONUs is configured with a remote antenna, and the ONU configured with the remote antenna combines data received by the remote antenna with the upstream optical signal,

wherein the ONU connected to the second optical fiber comprises an upstream transmitter for converting an electrical signal to be uploaded to generate the upstream optical signal and transmitting the upstream optical signal back to the second optical fiber; and

wherein each of the ONUs connected to the third, . . . n^th optical fiber respectively comprises an upstream receiver and an upstream transmitter;

the upstream receiver receives and converts the upstream optical signal into a received electrical signal; and

the upstream transmitter combines an electrical signal to be uploaded with the received electrical signal to generate the upstream optical signal, and transmits the upstream optical signal back to the corresponding third, . . . n^th optical fiber.

18. The PON system according to claim 17, wherein each of the ONUs comprises a coarse wavelength division multiplexer (CWDM) for splitting the received optical signals into the upstream optical signal and the downstream optical signal.

19. The PON system according to claim 18, wherein each of the ONUs comprises an optical switch and a first reflecting mirror;

the optical switch receives the optical signals;

upon being powered on, the optical switch guides the optical signals to the CWDM;

upon being powered off, the optical switch guides the optical signals to the first reflecting mirror; and

the first reflecting mirror reflects the optical signals back to the optical switch, and the optical switch then guides the optical signals back to the optical fiber connected to the ONU.

20. The PON system according to claim 18, wherein each of the ONUs comprises a downstream receiver for performing a decoding process on the downstream optical signal from the CWDM.

21. The PON system according to claim 17, wherein the upstream transmitter of the ONU configured with the remote antenna combines the data received by the remote antenna with the electrical signal to be uploaded and the received electrical signal to generate the upstream optical signal, and transmits the upstream optical signal back to the corresponding second, . . . n^th optical fiber.

22. The PON system according to claim 17, wherein each of the ONUs further comprises a second optical coupler having two splitting ends and one combining end;

the combining end receives the upstream optical signal from the corresponding optical fiber; and

the two splitting ends are respectively connected to the upstream receiver and the upstream transmitter.

23. The PON system according to claim 17, wherein each of the ONUs comprises:

a photoelectric converting element, for converting the upstream optical signal from the corresponding optical fiber into a first electrical signal;

a power splitter, for splitting the first electrical signal into a second electrical signal and a third electrical signal;

a digital processing controller, for receiving the second electrical signal, and combining the second electrical signal with an electrical signal to be uploaded to output a fourth electrical signal;

a first band pass filter, for filtering the third electrical signal to enable the third electrical signal within a predetermined frequency band range to pass through, so as to form a fifth electrical signal;

an electrical coupler, for coupling the fourth electrical signal with the fifth electrical signal to form a sixth electrical signal; and

an electro-optical converting element, for converting the sixth electrical signal into the upstream optical signal.

24. The PON system according to claim 23, wherein each of the ONUs further comprises a band stop filter for performing a band stop on the second electrical signal and then outputting the second electrical signal to the digital processing controller.

25. The PON system according to claim 23, wherein the ONU configured with the remote antenna further comprises:

a frequency shifter, for performing a frequency shift on the data received by the remote antenna;

a second band pass filter, for filtering the frequency-shifted data to enable the frequency-shifted data within the predetermined frequency band range to pass through, so as to form a seventh electrical signal; and

a combiner, for combining the fifth electrical signal with the seventh electrical signal to form an eighth electrical signal, wherein the electrical coupler couples the eighth electrical signal with the fourth electrical signal to form the sixth electrical signal.

26. The PON system according to claim 23, wherein the digital processing controller comprises:

an analog to digital converter, for converting the second electrical signal into a digital signal;

an orthogonal frequency division multiplexing (OFDM) demodulator, for demodulating the digital signal into a demodulated signal;

a data access controller, for combining the demodulated signal with the electrical signal to be uploaded;

an OFDM modulator, for performing an orthogonal modulation on a combined signal; and

a digital to analog converter, for converting a modulated signal into an analog signal to output the analog signal as the fourth electrical signal.

27. The PON system according to claim 17, wherein the downstream optical signal sent from the OLT comprises a data signal and a RF signal, and the ONU configured with the remote antenna transmits the RF signal through the remote antenna.

28. The PON system according to claim 27, wherein each of the ONUs connected to one of the third, . . . n^th optical fiber and configured with the remote antenna comprises:

a CWDM, receiving the optical signals from the corresponding optical fiber and splitting the received optical signals into a upstream optical signal and downstream optical signal;

a photoelectric converting element, receiving and converting the split downstream optical signal into an downstream electrical signal;

a power splitter, splitting the downstream electrical signal into two ninth electrical signals;

a band pass filter, filtering one of the ninth electrical signals to pass the RF signal within a predetermined frequency band range to form a passed electrical signal;

a transmitting and receiving switch;

transmitting the passed electrical signal through the remote antenna;

a band stop filter, stopping the other one of the ninth electrical signals within the predetermined frequency band range to form a stopped electrical signal;

a downstream receiver, receiving and processing the stopped electrical signal;

a first reflecting mirror;

a circulator;

an optical switch, receiving the split upstream optical signal and normally guiding the split upstream optical signal to the circulator, upon powered off, the optical switch guiding the split upstream optical signal to the first reflecting mirror, the reflecting mirror reflecting the received upstream optical signal back to the corresponding optical fiber;

an upstream receiver, the circulator guiding the upstream optical signal from the optical switch to the upstream receiver, the upstream receiver receiving and converting the upstream optical signal from the circulator into a received electrical signal; and

an upstream transmitter, receiving and combining the received electrical signal with the data received by the remote antenna and then transmitting the combined signal to the circulator, the circulator guiding the combined signal to the optical switch.

29. The PON system according to claim 17, wherein the optical circulator assembly comprises:

an optical splitter, having one joining end and n branch ends, wherein n is a positive integer greater than 2, the joining end is opto-connected to the first optical fiber, the optical splitter splits the downstream optical signal from the first optical fiber and then guides the downstream optical signal to the second, . . . n^th branch ends, and combines the upstream optical signal from the second, . . . n^th branch ends respectively and then guides the upstream optical signal to the joining end;

(n−

2) optical couplers, each having a combining end, a first splitting end, and a second splitting end, wherein the second, . . . (n−

1)^th branch ends are respectively connected to the first splitting ends of the first, second, . . . (n−

2)^th optical couplers, and each optical coupler couples the optical signals from the first and second splitting ends and guides the optical signal to the combining end; and

(n−

1) circulators, wherein first, second, . . . (n−

1)^th circulators are respectively connected to the second, third . . . n^th optical fibers;

the first circulator is connected to the first branch end;

the first, second, . . . (n−

2)^th circulators are respectively connected to the second splitting ends of the first, second, . . . (n−

2)^th optical couplers;

the combining ends of the first, second, . . . (n−

2)^th optical couplers are respectively connected to the second, . . . (n−

1)^th circulators;

the (n−

1)^th circulator is connected to the n^th branch end;

the first circulator guides the downstream optical signal from the first branch end to the second optical fiber, and guides the upstream optical signal from the second optical fiber to the correspondingly connected second splitting end;

the second, . . . (n−

2)^th circulators respectively guide the optical signals from the correspondingly connected combining ends to the third, . . . (n−

1)^th optical fibers, and guide the upstream optical signals from the third, . . . (n−

1)^th optical fibers to the correspondingly connected second splitting ends; and

the (n−

1)^th circulator guides the optical signal from the correspondingly connected combining end to the n^th optical fiber, and guides the upstream optical signal from the n^th optical fiber to the n^th branch end.