RADIO OVER FIBER LINK APPARATUS OF TIME DIVISION DUPLEX SCHEME

• US 20080145061A1
• Filed: 12/11/2007
• Published: 06/19/2008
• Est. Priority Date: 12/13/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: LEE, Han-Lim, Hwang, Seong-Taek, Kim, Hoon
• Granted Patent: US 8,041,222 B2
• Time in Patent Office: Days
• US Class Current: 398/139
• CPC Class Codes: H04B 10/25758 between a central unit and a single remote unit by means of an optical fibre
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0305 in end terminals
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A radio over fiber link apparatus for transmitting/receiving radio frequency up/downlink signals in a TDD mobile communication system. The radio over fiber link apparatus includes a center site for receiving radio frequency signals from an access point of the mobile communication system. The center site has a first electro-optic converter for converting the radio frequency signals into optical signals, bias control of the first electro-optic converter being performed based on the switching of TDD signals; and a remote for transmitting the radio frequency signals to a mobile communication terminal through an antenna. The remote site has a first photoelectric converter for converting the optical signals transmitted through an optical fiber from the center site into radio frequency signals.

Claims

1. A radio over fiber link apparatus for transmitting/receiving radio frequency up/downlink signals in a TDD mobile communication system, the radio over fiber link apparatus comprising:

a center site for receiving radio frequency signals from an access point of the TDD mobile communication system, the center site having a first electro-optic converter for converting the radio frequency signals into optical signals, bias control of the first electro-optic converter being performed based on the switching of TDD signals supplied from the access point and received by the center site; and

a remote site for receiving the optical signals converted by the first electro-optic converter and after converting the optical signals back into radio frequency signals, transmitting the radio frequency signals;

the remote site including a first photoelectric converter for converting the optical signals transmitted from the center site into radio frequency signals.

2. The radio over fiber link apparatus according to claim 1, further comprising:

an optical fiber that optically links the center site to the remote site for two-way communication between the center site and the remote site; and

an antenna being in communication with the remote site for transmitting the radio frequency signals to a mobile communication terminal within a transmission range of the radio frequency signals.

3. The radio over fiber link apparatus as claimed in claim 2, wherein the center site further comprises:

a gain block for receiving the radio frequency signals from the access point of the mobile communication system, amplifying signal components after reducing a noise component of the radio frequency signals, and providing the amplified signals as input signals of the electro-optic converter; and

a first WDM for multiplexing the optical signals, transmitted from the first electro-optic converter, at different wavelengths and transmitting the multiplexed signals to the remote site through the optical fiber, and de-multiplexing the optical signals transmitted through the optical fiber from the remote site at different wavelengths;

a photoelectric converter for converting the optical signals transmitted from the first WDM into radio frequency signals; and

a first low noise amplifier for amplifying the radio frequency signals transmitted from the photoelectric converter until they have Root Mean Square (RMS) power, so as to transmit the amplified signals to the access point of the mobile communication system.

4. The radio over fiber link apparatus as claimed in claim 3, wherein the remote site further comprises:

a second WDM for de-multiplexing the optical signals transmitted through an optical fiber from the center site into optical signals having different wavelengths as de-multiplexed signals for input to the first photoelectric converter, and multiplexing optical signals for transmission from the remote site to the center site through an optical fiber at different wavelengths;

a second low noise amplifier for substantially eliminating noise in the radio frequency signals transmitted from the first photoelectric converter and amplifying only a signal component;

a coupler for extracting a portion of the radio frequency signals from the second low noise amplifier;

a high power amplifier for amplifying the radio frequency signals transmitted from the second low noise amplifier until the radio frequency signals transmitted from the second low noise amplifier have an RMS power suitable for wireless transmission to a mobile communication terminal;

a third low noise amplifier for eliminating noise of radio frequency signals transmitted from the antenna and amplifying only a signal component of the radio frequency signals;

a second electro-optic converter for converting radio frequency signals transmitted from the third low noise amplifier into optical signals;

a switch for transmitting the radio frequency signals transmitted from the high power amplifier to the antenna in receive (Rx) mode and providing the radio frequency signals transmitted from the antenna to the third low noise amplifier in a transmit (Tx) mode; and

a switching timing signal generation circuit for controlling the switch after dividing a downlink and an uplink by radio frequency signals extracted from the coupler.

5. The radio over fiber link apparatus as claimed in claim 4, wherein the first electro-optic converter comprises:

an optical signal generator for generating optical signals; and

a Bias-T for receiving radio frequency signals from the access point of the mobile communication system through one port thereof, and receiving TDD signals through another port thereof and providing the received TDD signals as bias signals of the optical signal generator.

6. The radio over fiber link apparatus as claimed in claim 3, wherein the first electro-optic converter comprises:

an optical signal generator for generating optical signals; and

a Bias-T for receiving radio frequency signals from the access point of the mobile communication system through one port thereof, and receiving TDD signals through another port thereof and providing the received TDD signals as bias signals of the optical signal generator.

7. The radio over fiber link apparatus as claimed in claim 4, wherein the first electro-optic converter comprises:

an optical signal generator for generating optical signals; and

a Bias-T for receiving radio frequency signals from the access point of the mobile communication system through one port thereof, and receiving TDD signals through another port thereof and providing the received TDD signals as bias signals of the optical signal generator.

8. The radio over fiber link apparatus as claimed in claim 5, wherein the bias signals are applied to a point between a null point and an operation point on a modulation curve of the optical signal generator.

9. The radio over fiber link apparatus as claimed in claim 5, wherein the optical signal generator includes a laser diode.

10. The radio over fiber link apparatus as claimed in claim 9, wherein the optical signal generator further comprises an interferometer type modulator for modulating lights generated from the laser diode.

11. The radio over fiber link apparatus as claimed in claim 10, wherein the interferometer type modulator comprises a Mach-Zehnder (MZ) modulator, and wherein the Bias-T comprises a capacitor and inductor, and the TDD signals supplied from the access point are applied to the MZ modulator via the inductor.

12. The radio over fiber link apparatus as claimed in claim 1, wherein the first photoelectric converter is based on the switching of the TDD signals for the bias control.

13. The radio over fiber link apparatus as claimed in claim 4, wherein the first photoelectric converter is based on the switching of the TDD signals for the bias control.

14. The radio over fiber link apparatus as claimed in claim 13, wherein the optical power in the RX mode is about 20 dB lower than the optical power of the Tx mode.

15. A center site apparatus for radio over fiber link transmission, said apparatus comprising:

a center site for receiving radio frequency signals from an access point of the TDD mobile communication system, the center site having a first electro-optic converter for converting the radio frequency signals into optical signals, bias control of the first electro-optic converter being performed based on the switching of TDD signals supplied from the access point and received by the center site;

a gain block for receiving the radio frequency signals from the access point of the mobile communication system, amplifying signal components after reducing a noise component of the radio frequency signals, and providing the amplified signals as input signals of the electro-optic converter; and

a first WDM for multiplexing the optical signals, transmitted from the first electro-optic converter, at different wavelengths and transmitting the multiplexed signals to a remote site through an optical fiber, and de-multiplexing the optical signals transmitted through the optical fiber from the remote site at different wavelengths;

a photoelectric converter for converting the optical signals transmitted from the first WDM into radio frequency signals; and

a first low noise amplifier for amplifying the radio frequency signals transmitted from the photoelectric converter until they have Root Mean Square (RMS) power, so as to transmit the amplified signals to the access point of the mobile communication system;

an optical signal generator for generating optical signals; and

a Bias-T for receiving radio frequency signals from the access point of the mobile communication system through one port thereof, and receiving TDD signals through another port thereof and providing the received TDD signals as bias signals of the optical signal generator.

16. A remote site apparatus for radio over fiber link transmission, said apparatus comprising:

a first photoelectric converter for converting the optical signals received from a center site into radio frequency signals;

a WDM for de-multiplexing the optical signals received through an optical fiber from the center site into optical signals having different wavelengths as de-multiplexed signals for input to the first photoelectric converter, and multiplexing optical signals for transmission from the remote site to the center site through an optical fiber at different wavelengths;

a low noise amplifier for substantially eliminating noise in the radio frequency signals transmitted from the first photoelectric converter and amplifying only a signal component;

a coupler for extracting a portion of the radio frequency signals from the low noise amplifier;

a high power amplifier for amplifying the radio frequency signals transmitted from the low noise amplifier until the radio frequency signals transmitted from the low noise amplifier have an RMS power suitable for wireless transmission to a mobile communication terminal;

a second low noise amplifier for eliminating noise of radio frequency signals transmitted from the antenna and amplifying only a signal component of the radio frequency signals;

an electro-optic converter for converting radio frequency signals transmitted from the third low noise amplifier into optical signals;

a switch for transmitting the radio frequency signals transmitted from the high power amplifier to the antenna in receive (Rx) mode and providing the radio frequency signals transmitted from the antenna to the third low noise amplifier in a transmit (Tx) mode; and

a switching timing signal generation circuit for controlling the switch after dividing a downlink and an uplink by radio frequency signals extracted from the coupler.

17. A radio over fiber link apparatus for transmitting/receiving radio frequency up/downlink signals in a TDD mobile communication system, the radio over fiber link apparatus comprises:

a center site for receiving radio frequency signals from an access point of the TDD mobile communication system, the center site having an electro-optic converter for converting the radio frequency signals into optical signals and an optical switch for receiving optical signals transmitted from the electro-optic converter, the optical switch being controlled based on the switching of the TDD signals; and

a remote site for transmitting the radio frequency signals to a mobile communication terminal through an antenna, the remote having a photoelectric converter for converting the optical signals transmitted through an optical fiber from the center site into radio frequency signals.