Title :
Modulatable orthogonal sequences and their application to SSMA systems
Author :
Suehiro, Naoki ; Hatori, Mitsutoshi
Author_Institution :
Toshiba Corp., Tokyo, Japan
fDate :
1/1/1988 12:00:00 AM
Abstract :
A set of N-1 orthogonal sequences of period N 2 is proposed, where N is a natural number. Each orthogonal sequence proposed can be modulated by N complex numbers of absolute value 1, so the modulated sequence is also orthogonal. When N is an odd prime number, the absolute value of the cross-correlation function between any two of the N-1 orthogonal sequences is constant and satisfies the mathematical lower bound. This property of the cross-correlation function is not changed when each of the two orthogonal sequences is modulated by N complex numbers of absolute value 1. Two spread-spectrum multiple-access (SSMA) systems using these sequences are proposed. One system is an asynchronous SSMA system, using the proposed sequences unmodulated. The cochannel interference peak between any two channels in this system realizes the mathematical lower bound for an asynchronous SSMA system using a set of orthogonal sequences. The other system is a synchronous SSMA system without cochannel interference which uses the modulated form of the proposed sequences
Keywords :
binary sequences; multi-access systems; spread spectrum communication; SSMA systems; asynchronous system; cochannel interference; cross-correlation function; modulated sequence; orthogonal sequences; spread-spectrum multiple-access; synchronous system; Autocorrelation; Binary sequences; Information technology; Information theory; Interchannel interference; Spread spectrum communication;
Journal_Title :
Information Theory, IEEE Transactions on
