Transmitter and receiver

Abstract

A transmitter for use in a communication system uses a orthogonal modulation method, and the transmitter includes: an orthogonal sequence prescriber 12 that prescribes association between orthogonal signals and information words determined on the basis of sizes of differences between information words of a plurality of mutually different information words and a probability of occurrence of decision errors between orthogonal signals of a plurality of mutually orthogonal signals; and a symbol mapper 11 that, upon input of any of the information words, generates modulation symbols based on the orthogonal signals associated with the input information word according to the associations prescribed by the orthogonal sequence prescriber.

1 . A receiver comprising:
 a correlation processor to find a correlation between a plurality of orthogonal signals that are mutually orthogonal and an input signal obtained from a signal received from an opposing transmitter; and
 a determiner to: 
 determine, based on the correlation found by the correlation processor, which of the orthogonal signals has been transmitted by the opposing transmitter, and 
 restore an information word corresponding to a determined orthogonal signal based on an association between the information words and the orthogonal signals determined based on a size of differences between a plurality of mutually different information words and an inter-signal point distance between the orthogonal signals; wherein 
 the association between the information words and the orthogonal signals is determined by at least one of the following: 
 among the combinations of the information words, associating combinations for which the size of the difference is maximum with, among combinations of the orthogonal signals, combinations for which the inter-signal point distance is maximum; and 
 among the combinations of the information words, associating combinations for which the size of the difference is minimum with, among the combinations of orthogonal signals, combinations for which the inter-signal point distance is minimum. 
   
     
     
         2 . The receiver according to  claim 1 , wherein
 the orthogonal signals are bi-orthogonally modulated; and   among the combinations of the orthogonal signals, in each of the combinations for which the inter-signal point distance is minimum, the orthogonal signals have adjacent phase rotation amounts and are identical except for the phase rotation amounts.   
     
     
         3 . The receiver according to  claim 1 , wherein
 the orthogonal signals are bi-orthogonally modulated;   the signal received from the opposing transmitter is a signal transmitted by the transmitter after rotating phase of modulation symbols by phase rotation amounts that differ from one another according to a transmission timing of the modulation symbols; and   the receiver further comprises a phase rotator that rotates phase of the input signal obtained from the signal received from the opposing transmitter to cancel the phase rotated in the transmitter, and that inputs the phase-rotation-canceled signal to the correlation processor.   
     
     
         4 . The receiver according to  claim 1 , wherein
 the orthogonal signals are bi-orthogonally modulated based on orthogonal frequency shift keying (FSK).