Method and apparatus for duplex communication in hybrid fiber-radio systems

Abstract

An apparatus and method for enabling cost-effective duplex communication by diplexing one of down stream signals for frequency up-conversion in a hybrid fiber-radio system includes diplexing an unmodulated mode signal among beating signals between a master laser and an injection-locked slave laser and using the diplexed signal for down-conversion in upstream transmission, thereby eliminating the need for expensive high-frequency local oscillators for frequency conversion. Higher radio frequency signals can be generated using beating between basic modes and satellite modes such as FWM conjugates of the master laser and slave laser. Cost-effective systems, stabilization of a light source and improved transmission performance may be achieved by using a diplexer instead of an expensive high-frequency local oscillator.

1 . (canceled) 
   
   
       2 . An apparatus for duplex communication in a hybrid fiber-radio system, the apparatus at a remote station comprising:
 an optical-to-electrical converter for converting received optical signals into electrical signals;   a diplexer for splitting data mode signals containing user source data and unmodulated mode signals;   a radio transmitter for converting the data mode signals into wireless radio signals and for transmitting the wireless radio signals wirelessly;   a radio receiver for converting received wireless radio signals into electrical signals;   a mixer for mixing diplexed signals and the electrical signals and outputting mixed electrical signals; and   a laser for converting the mixed electrical signals into optical signals.   
   
   
       3 . (canceled) 
   
   
       4 . A method of uplink transmission in a method for duplex communication in a hybrid fiber-radio system comprising:
 (a) converting signals wirelessly received by an antenna into electrical signals;   (b) mixing diplexed unmodulated mode signals with the electrical signals to form mixed electrical signals;   (c) down-converting a signal band of data;   (d) generating optical signals with a laser driven by the mixed electrical signals;   (e) transmitting the optical signals over an optical fiber; and   (f) receiving the optical signals with a photodetector at a central office.   
   
   
       5 . (canceled) 
   
   
       6 . A computer-readable recording medium on which a program for executing the method claimed in  claim 4  is recorded. 
   
   
       7 . An apparatus for duplex communication in a hybrid fiber-radio system as claimed in  claim 2 , wherein the data mode signals are modulated data mode signals and the unmodulated mode signals are unmodulated non-data mode signals. 
   
   
       8 . An apparatus for duplex communication in a hybrid fiber-radio system as claimed in  claim 7 , wherein the diplexed signals mixed by the mixer are the unmodulated non-data mode signals. 
   
   
       9 . An apparatus for duplex communication in a hybrid fiber-radio system as claimed in  claim 2 , further comprising an optical routing device for launching optical signals from the laser over an optical transmission fiber. 
   
   
       10 . A method of uplink transmission in a method for duplex communication in a hybrid fiber-radio system as claimed in  claim 4 , wherein unmodulated mode signals are unmodulated non-data mode signals. 
   
   
       11 . A communication system comprising a central station and one or more remote stations, wherein each remote station includes:
 an optical-to-electrical converter for converting received optical signals into electrical signals;   a diplexer for splitting data mode signals containing user source data and unmodulated mode signals;   a radio transmitter for converting the data mode signals into wireless radio signals and for transmitting the wireless radio signals wirelessly;   a radio receiver for converting received wireless radio signals into electrical signals;   a mixer for mixing diplexed signals and the electrical signals and outputting mixed electrical signals; and   a laser for converting the mixed electrical signals into optical signals.