System and Method For Embedding Phase and Amplitude Into A Real-Valued Unipolar Signal

Abstract

A system for embedding phase and amplitude into a real valued unipolar signal suitable for intensity modulation (IM) by optical transmitters. The system includes a complex-to-unipolar conversion engine configured to receive complex symbols in Cartesian format and convert the complex symbols from the Cartesian format to a polar coordinate format and generate real valued unipolar symbols including embedded phase and amplitude information of complex symbols in the Cartesian format.

What is claimed is: 
     
         1 . A system for embedding phase and amplitude into a real valued unipolar signal suitable for intensity modulation (IM) by optical transmitters, the system comprising:
 a complex-to-unipolar conversion engine configured to receive complex symbols in Cartesian format and convert the complex symbols from the Cartesian format to a polar coordinate format and generate real valued unipolar symbols including embedded phase and amplitude information of complex symbols in the Cartesian format.   
     
     
         2 . The system of  claim 1  in which the complex symbols include one or more of: complex orthogonal frequency division multiplexing (OFDM) symbols or single-carrier frequency domain-equalization (SC-FDE) symbols. 
     
     
         3 . The system of  claim 1  in which the complex-to-unipolar conversion engine includes a Cartesian-to-polar converter configured to convert the complex symbols from the Cartesian format to the complex symbols in polar coordinate format. 
     
     
         4 . The system of  claim 3  in which the complex-to-unipolar conversion engine includes a phase and amplitude pre-equalizer responsive to the complex symbols in the polar format configured to set values of the phase and amplitude of individual samples of the complex symbols in the polar format in order to optimize bit error rate under dynamic range operation constraints at a predetermined data rate and output equalized amplitude and phase samples having the embedded amplitude and phase. 
     
     
         5 . The system of  claim 4  further including unipolar symbol generator responsive to the equalized amplitude and phase samples configured to generate the real valued unipolar symbols including the embedded amplitude and phase. 
     
     
         6 . The system of  claim 5  further including a data bit generator responsive to a data bit stream configured to generate bit symbols. 
     
     
         7 . The system of  claim 6  further including a quadrature amplitude modulator (QAM) responsive to the data bit symbols configured to generate complex QAM symbols. 
     
     
         8 . The system of  claim 6  further including a phase-shift keying (PSK) modulator responsive to the data bit symbols configured to generate complex PSK symbols. 
     
     
         9 . The system of  claim 7  further including a mapper responsive to the QAM symbols configured to assign the QAM symbols to all sub-carriers to a Fourier Transform (IFFT) engine operation with no Hermitian symmetry to double spectral efficiency. 
     
     
         10 . The system of  claim 9  further including an inverse fast Fourier Transform (IFFT) engine responsive to the assigned. QAM symbols on stab-carriers configured to output complex OFDM symbols. 
     
     
         11 . The system of  claim 10  in which amplitudes of different samples of complex valued OFDM symbols are transmitted on one half of a period and phases of different samples of complex valued OFDM symbols are transmitted on the other half of the period. 
     
     
         12 . The system of  claim 7  further including a mapper responsive to the QAM symbols configured to assign the QAM symbols only to even sub-carriers to a Fourier Transform (IFFT) engine operation with no Hermitian symmetry to double the spectral efficiency. 
     
     
         13 . The system of  claim 12  further including an inverse fast Fourier Transform (IFFT) engine responsive to the assigned QAM symbols to the even sub-carriers configured to output the complex OFDM symbols using half-wave even symmetry to reduce the time required to transmit complex OFDM symbols. 
     
     
         14 . The system of  claim 10  further including a digital-to-analog converter configured to convert the real valued unipolar OFDM symbols with the embedded phase and amplitude information to analog signals. 
     
     
         15 . The system of  claim 14  further including an optical receiver including an analog-to-digital converter responsive to the analog signals configured to convert the analog signals to digital symbols representing the real valued unipolar OFDM symbols with the embedded phase and amplitude information. 
     
     
         16 . The system of  claim 15  further including a unipolar-to-complex conversion engine configured to convert the symbols representing real valued unipolar OFDM symbols with embedded phase and amplitude information into complex OFDM symbols. 
     
     
         17 . The system of  claim 16  in which the unipolar-to-complex conversion engine includes a polar-to-Cartesian engine configured to convert the samples representing the real valued unipolar symbols with embedded phase and amplitude information in the polar coordinate format to Cartesian format. 
     
     
         18 . A system for embedding phase and amplitude into a real valued unipolar signal suitable for intensity modulation (IM) by optical transmitters, the system comprising:
 a Cartesian-to-polar converter configured to receive complex symbols in Cartesian format and convert the complex symbols from the Cartesian format to a polar coordinate format;   a phase and amplitude pre-equalizer responsive to the complex symbols in polar format configured to set the values of the phase and amplitude of individual samples of the complex symbols in the polar format in order to optimize bit error rate under dynamic range operation constraints at a predetermined data rate and output equalized amplitude and phase samples having embedded amplitude and phase information; and   unipolar symbol generator responsive to the equalized amplitude and phase samples in the polar format configured to construct the real-valued unipolar symbols including embedded amplitude and phase.   
     
     
         19 . A method for embedding phase and amplitude into a real-valued unipolar signal suitable for intensity modulation (IM) by optical transmitters, the method comprising:
 receiving complex symbols in Cartesian format;   converting the complex symbols from the Cartesian format to a polar coordinate format; and   generating real-valued unipolar symbols included in embedded phase and amplitude information of the complex symbols in Cartesian format.   
     
     
         20 . The method of  claim 19  further including the step of setting values of the phase and amplitude of individual samples of the complex symbols in polar format in order to optimize bit error rate under dynamic operation constraints and a predetermined rate and outputting equalized embedded amplitude and phase samples. 
     
     
         21 . The method of  claim 20  further including the step of generating real-valued unipolar symbols including the embedded phase and amplitude from the equalized amplitude and phase samples.