Wireless transmission using fiber link

• US 5,987,303 A
• Filed: 05/29/1996
• Issued: 11/16/1999
• Est. Priority Date: 05/29/1996
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Freeman, Paul Nathan, Dutta, Niloy Kumar
• Primary Examiner(s): Le, Vu
• Application Number:
  US08/655,016
• Time in Patent Office: 1,266 Days
• Field of Search: 455/3.1, 455/5.1, 455/6.3, 455/67.1, 455/422, 348/6, 348/12, 348/13, 348/14, 348/10, 370/328, 359/115, 359/117, 359/125, 359/136-137, 359/145, 359/152, 359/172-173
• US Class Current: 725/106
• CPC Class Codes: H04B 10/25751 Optical arrangements for CATV or video distribution adaptations of television systems for optical transmission H04N7/22
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission

Abstract

A wireless transmission and reception system includes a mixing section using a phase shift keying or quadrature amplitude modulation scheme to modulate a baseband signal, representing voice or data, onto a carrier frequency within the range of standard (cable television format) AM-VSB frequencies. A combiner section combines the modulated carrier signal into a channel of a multiplexed cable television (CATV) signal having two or more channels. The CATV signal is used to modulate a laser source. The laser source generates a laser signal based on the CATV signal. The laser signal is optically coupled into a bidirectional fiber link. The fiber link transmits the laser signal and ultimately converts the laser signal into the electrical CATV signal. A splitting section coupled to the bidirectional fiber link splits the modulated carrier signal from the CATV signal. A demodulating section coupled to the splitting section recovers the baseband signal from the modulated carrier signal. The baseband signal is remodulated onto a carrier signal having a designated wireless frequency and is broadcast into free space using an antenna. Signals received by the antenna from free space are amplified and passed through the bidirectional fiber link.

Claims

1. A method for wireless voice and data transmission and reception, comprising the steps of:

modulating a baseband signal onto a first carrier signal having a designated cable frequency to generate a modulated first carrier signal;

the baseband signal has a symbol rate in the range from 1.228 Mb/s to 2.0 Mb/s;

the modulated first carrier signal has a bandwidth less than or equal to 2.5 MHz;

combining the modulated first carrier signal into a channel at the designated cable frequency of a CATV signal having two or more channels, wherein

the two or more channels include a lowest frequency channel at a lowest frequency of the CATV signal and a highest frequency channel at a highest frequency of the CATV signal, and

the designated cable frequency is greater than the lowest frequency of the CATV signal and less than the highest frequency of the CATV signal;

optically coupling a laser signal into a fiber link responsive to the CATV signal;

converting the laser signal from the fiber link into the CATV signal;

splitting the modulated first carrier signal from the CATV signal;

demodulating the modulated first carrier signal to recover the baseband signal; and

mixing the baseband signal onto a second carrier signal having a designated wireless frequency.

2. The method of claim 1, further comprising the step of:

broadcasting the second carrier signal using an antenna.

3. The method of claim 1, wherein the fiber link includes:

an optical fiber coupled to receive the laser signal, and

a bidirectional optical receiver coupled to receive the laser signal from the optical fiber converting the laser signal into the CATV signal.

4. The method of claim 1, wherein:

the baseband signal is presented in a format selected from the group consisting of CDMA, TDMA, and FDMA.

5. The method of claim 1, further comprising the steps of:

receiving a radio signal from free space using the antenna; and

coupling the radio signal into the fiber link.

6. A wireless transmission and reception system, comprising:

means for modulating a baseband signal onto a first carrier signal having a designated cable frequency to generate a modulated first carrier signal;

the baseband signal has a symbol rate in the range from 1.228 Mb/s to 2.0 Mb/s;

the modulated first carrier signal has a bandwidth less than or equal to 2.5 MHz;

means for combining the modulated first carrier signal into a channel at the designated cable frequency of a CATV signal having two or more channels;

wherein

the two or more channels include a lowest frequency channel at a lowest frequency of the CATV signal and a highest frequency channel at a highest frequency of the CATV signal, and

the designated cable frequency is greater than the lowest frequency of the CATV signal and less than the highest frequency of the CATV signal;

means for optically coupling a laser signal into a fiber link responsive to the CATV signal;

means for converting the laser signal from the fiber link into the CATV signal;

means for splitting the modulated first carrier signal from the CATV signal;

means for demodulating the modulated first carrier signal to recover the baseband signal;

means for mixing the baseband signal onto a second carrier signal having a designated wireless frequency; and

an antenna for broadcasting the second carrier signal.

7. The wireless transmission and reception system of claim 6, wherein:

the means for modulating uses a modulation technique selected from the group consisting of phase shift keying and quadrature amplitude modulation.

8. The wireless transmission and reception system of claim 6, further comprising:

a circulator coupled to the antenna receiving a radio signal from free space; and

a bidirectional optical receiver for coupling the radio signal into the fiber link.

9. The wireless transmission and reception system of claim 6, further comprising:

means, coupled to the means for combining, for generating the CATV signal having two or more channels.

10. A transmission and reception system, comprising:

a modulator outputting a carrier signal modulated by a baseband signal;

the baseband signal has a symbol rate in the range from 1.228 Mb/s to 2.0 Mb/s;

a combiner combining the modulated carrier signal into a channel at a designated cable frequency of a CATV signal having two or more channels;

wherein

the two or more channels include a lowest frequency channel at a lowest frequency of the CATV signal and a highest frequency channel at a highest frequency of the CATV signal, and

the designated cable frequency is greater than the lowest frequency of the CATV signal and less than the highest frequency of the CATV signal;

the modulated carrier signal has a bandwidth less than or equal to 2.5 MHz;

an analog quality laser source generating a laser signal responsive to the CATV signal;

a fiber link receiving the laser signal from the laser source and converting the laser signal into the CATV signal;

a splitter splitting the modulated carrier signal from the CATV signal; and

a demodulation circuit recovering the baseband signal from the modulated carrier signal.

11. The system of claim 10, wherein the fiber link includes:

an optical fiber coupled to receive the laser signal from the laser source, and

an optical receiver coupled to receive the laser signal from the optical fiber and for converting the laser signal into the CATV signal.

12. The system of claim 10, further comprising:

a bandpass filter coupled to the splitter filtering the modulated carrier signal; and

an amplifier coupled to the bandpass filter amplifying the modulated carrier signal.

13. The system of claim 10, further comprising:

a low pass filter coupled to the demodulation circuit filtering the recovered baseband signal.

14. A wireless transmission and reception system, comprising:

a modulator modulating a baseband signal onto a first carrier signal having a designated cable frequency;

the baseband signal has a symbol rate in the range from 1.228 Mb/s to 2.0 Mb/s;

the modulated first carrier signal has a bandwidth less than or equal to 2.5 MHz;

a combiner combining the modulated first carrier signal into a channel at the designated cable frequency of a CATV signal having two or more channels;

wherein

the two or more channels include a lowest frequency channel at a lowest frequency of the CATV signal and a highest frequency channel at a highest frequency of the CATV signal, and

the designated cable frequency is greater than the lowest frequency of the CATV signal and less than the highest frequency of the CATV signal;

an analog quality laser source generating a laser signal based on the CATV signal;

a fiber link receiving the laser signal from the laser source and converting the laser signal into the CATV signal;

a splitter coupled to the fiber link splitting the modulated first carrier signal from the CATV signal;

a demodulator to recover the baseband signal from the modulated first carrier signal;

an upconverter to modulate the recovered baseband signal onto a second carrier signal having a designated wireless frequency; and

an antenna to broadcast the modulated second carrier signal into free space.

15. The transmission and reception system of claim 14, further comprising:

an amplifier coupled to the fiber link for amplifying the CATV signal.