System and method for orderwire modulation in a multipoint-to-point orthogonal frequency division multiplexing system

Abstract

Systems and methods for orderwire modulation in a multipoint-to-point orthogonal frequency division multiplexing (OFDM) system are provided. In one embodiment, a method comprises: receiving baseband user data; modulating the baseband user data onto a first plurality of parallel streams based on a first modulation constellation; modulating non-user data onto a second plurality of parallel streams based on a second modulation constellation, wherein the first modulation constellation provides a higher bit-rate than the second modulation constellation; applying an inverse Fourier transform to the first and second plurality of parallel streams to produce a set of complex time-domain samples; transmitting a radio frequency transmission signal based on the set of complex time-domain samples; and receiving a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein the plurality of spectrally overlapping carrier signals are modulated using an inverse Fourier transform.

1 . A method for communication, the method comprising: 
 receiving baseband user data;    modulating the baseband user data onto a first plurality of parallel streams based on a first modulation constellation;    modulating non-user data onto a second plurality of parallel streams based on a second modulation constellation, wherein the first modulation constellation provides a higher bit-rate than the second modulation constellation;    applying an inverse Fourier transform to the first plurality of parallel streams and the second plurality of parallel streams to produce a set of complex time-domain samples;    transmitting a radio frequency transmission signal based on the set of complex time-domain samples; and    receiving a waveform comprising a plurality of spectrally overlapping carrier signals from at least two of a plurality of remote units, wherein the plurality of spectrally overlapping carrier signals are modulated using an inverse Fourier transform.    
     
     
         2 . The method of  claim 1 , further comprising: 
 selecting the first modulation constellation based on a predefined category of information represented by the user data.    
     
     
         3 . The method of  claim 1 , wherein the inverse Fourier transform is based on one of an inverse Fast Fourier Transform and an inverse Discrete Fourier Transform.  
     
     
         4 . The method of  claim 1 , wherein the first modulation constellation is based on a Quadrature amplitude modulation (QAM) modulation scheme.  
     
     
         5 . The method of  claim 1 , wherein when the first modulation constellation is based on a Quadrature Amplitude Modulation (QAM) modulation scheme, the second modulation constellation is based on a Phase-Shift Keying (PSK) modulation scheme.  
     
     
         6 . A system comprising: 
 a plurality of remote units; and    a host unit communicatively coupled to the plurality of remote units in a multipoint-to-point configuration, the host unit receiving an orthogonal frequency division multiplexing waveform;    wherein the host unit modulates symbols onto at least one of a plurality of orthogonal carriers;    wherein the host unit maps user data onto a first plurality of parallel streams based on a first modulation constellation and maps non-user data onto a second plurality of parallel streams based on a second modulation constellation, wherein the first modulation constellation provides a higher bit-rate than the second modulation constellation;    wherein the host unit applies an inverse Fourier transform to the first plurality of parallel streams and the second plurality of parallel streams to produce a set of complex time-domain samples;    wherein the host unit transmits the set of complex time-domain samples to the plurality of remote units.    
     
     
         7 . The system of  claim 6 , wherein the host unit selects the first modulation constellation based on a predefined category of information represented by the user data.  
     
     
         8 . The system of  claim 6 , wherein the inverse Fourier transform is based on one of an inverse Fast Fourier Transform and an inverse Discrete Fourier Transform.  
     
     
         9 . The system of  claim 6 , wherein the first modulation constellation is based on a Quadrature amplitude modulation (QAM) modulation scheme.  
     
     
         10 . The system of  claim 6 , wherein when the first modulation constellation is based on a Quadrature Amplitude Modulation (QAM) modulation scheme, the second modulation constellation is based on a Phase-Shift Keying (PSK) modulation scheme.  
     
     
         11 . A method for Orthogonal Frequency Division Multiplexing (OFDM) multi-point to point communication, the method comprising: 
 determining a type of data to be transmitted;    based on the determination of the type of data to be transmitted, selecting a modulation scheme for the data;    wherein when the type of data to be transmitted is non-control data a first modulation scheme is selected, and when the type of data to be transmitted is control data a second modulation scheme is selected, where the second modulation scheme has fewer constellation points per symbol than the first modulation scheme; and    transmitting from a remote unit a signal having the data modulated thereon with the selected modulation scheme on at least one tone, the signal combining with a signal from at least one other remote unit on a different tone to form a coherent OFDM waveform.    
     
     
         12 . The method of  claim 11 , further comprising: 
 selecting the first modulation scheme based on a predefined category of information represented by the non-control data.    
     
     
         13 . The method of  claim 11 , further comprising: 
 receiving a waveform comprising a plurality of orthogonal tones from at least two of a plurality of remote units, wherein the plurality of orthogonal tones are modulated using an inverse Fourier transform.    
     
     
         14 . The method of  claim 11 , wherein the first modulation scheme is based on a Quadrature amplitude modulation (QAM) modulation scheme.  
     
     
         15 . The method of  claim 11 , wherein when first modulation scheme is based on a Quadrature Amplitude Modulation (QAM) modulation scheme, the second modulation scheme is based on a Phase-Shift Keying (PSK) modulation scheme.  
     
     
         16 . The method of  claim 11 , wherein spacing between tones of the coherent OFDM waveform is based on a reciprocal of a symbol period.  
     
     
         17 . The method of  claim 11 , wherein when the type of data to be transmitted is non-control data the data is transmitted on a first tone and when the type of data to be transmitted is control data the data is transmitted on a second tone.