Patent ID: 6414985
Filing Date: 2002-07-02
Classification: H04B,H04L

Abstract:
A radio communication system, comprising a plurality of base stations and terminals, said plurality of base stations and terminals being connected via spread spectrum communications, and using a code division multiple access, which performs orthogonal M-ary modulation on a data signal, followed by spread modulation, wherein each of said plurality of base stations includes:a circuit determining an in-phase component and a quadrature component by de-spreading a received signal sent from said terminal; a circuit determining correlation values of said in-phase component and quadrature component, which correspond to respective Hadamard matrices resulting from either a fast Hadamard transform or an inverse Hadamard transform performed on said in-phase component and quadrature component; a circuit computing the sum of the squares of the respective correlation values of said in-phase component and quadrature component; a circuit selecting either said fast Hadamard transform or inverse Hadamard transform output, which outputs the maximum value of said computed sum of the squares; a circuit carrying out coherent detection by complex multiplication of said selected fast Hadamard transform or inverse Hadamard transform output, and said in-phase component and quadrature component determined via said de-spreading; a circuit determining the correlation value by performing either a fast Hadamard transform or an inverse Hadamard transform on said coherent detection output; and a circuit converting to a data signal a Hadamard matrix corresponding to the maximum value of said determined correlation value.