Method And Apparatus For Generating M-ary CPM Waveforms From A Superposition Of PAM Waveforms

Abstract

To reflect advantages of a constant phase modulation waveform, the invention provides a pulse amplitude modulated PAM waveform that is a superposition of Q 0 ≦2 L−1 PAM component pulses in each symbol interval such that a significant portion of signal energy over each symbol interval is within the Q 0 PAM component pulses. The present invention distributes most signal energy in one pulse and progressively lower energies in the remaining Q 0 −1 pulses of a symbol interval. The Laurent Decomposition is a special case of the present invention, but the present invention exhibits the energy distribution of the Laurent Decomposition in non-binary CPM waveforms and in multi-h (binary and non-binary) CPM waveforms, where h is a modulating index. All energy is distributed among only Q=2 L−1 pulses in each symbol interval, though only Q 0 <Q pulses may in fact be transmitted in certain embodiments. A method, transmitter, receiver, and computer program are disclosed. Embodiments may exactly duplicate a CPM waveform, or approximate a CPM waveform.

1 .- 40 . (canceled) 
   
   
       41 . An apparatus comprising:
 a receiver configured to receive an M-ary pulse amplitude modulated PAM signal characterized in that, for each symbol interval, a plurality of pulses exhibit descending levels of signal energy, where M>2; and   a modulator configured demodulate symbols from the pulses.   
   
   
       42 . The apparatus of  claim 41 , wherein each symbol interval comprises Q 0 =2 L−1  PAM component pulses, where L represents a number of symbol intervals. 
   
   
       43 . The apparatus of  claim 41 , wherein the modulator is further configured to resolve pseudo symbols b k,n . 
   
   
       44 . The apparatus of  claim 41 , wherein the receiver comprises at least one antenna, and the modulator comprises a demodulator, a multiplier, a memory, and a processor. 
   
   
       45 . An apparatus comprising:
 a receiver configured to receive a binary multi-h pulse amplitude modulated PAM signal characterized in that, for each symbol interval, a plurality of pulses exhibit descending levels of signal energy, where h>1 is a modulating index; and   a modulator configured to demodulate symbols from the pulses.   
   
   
       46 . The apparatus of  claim 45 , wherein each symbol interval comprises Q 0 =2 L−1  PAM component pulses, where L represents a number of symbol intervals. 
   
   
       47 . The apparatus of  claim 45 , wherein the modulator is further configured to resolve pseudo symbols b k,n . 
   
   
       48 . The apparatus of  claim 45 , wherein the receiver comprises at least one antenna, and the modulator comprises a demodulator, a multiplier, a memory, and a processor. 
   
   
       49 . A memory embodying a program of machine-readable instructions, executable by a digital data processor, to perform actions directed toward demodulating a received signal, the actions comprising:
 determining a generalized phase function of a received pulse amplitude modulated signal;   deriving a function g k,n (t-nT) from the generalized phase function, where T is a symbol duration;   for each n th  symbol interval and each pulse of Q 0 ≦2 L−1  pulse-amplitude modulated component pulses, resolving pseudo symbols b k,n  using the function g k,n (t-nT), where L represents a total number of symbol intervals; and   determining symbols from the pseudo symbols.   
   
   
       50 . (canceled)