Generating and processing of CDMA signals

摘要

Systems and methods for generating a CDMA signal s(t) comprising N components involves assigning to each of the N components one unique spreading sequence an selected from a set of M spreading sequences with M≧N, modulating the symbols dn of each component on the assigned unique spreading sequence an, and combining the N symbols dn each being spread with its own unique spreading sequence an to a CDMA signal s(t). The assigned spreading sequences an are selected such that all selected pairs within the set of N spreading sequences are orthogonal or very close to be orthogonal so that cross-correlation components between all spreading sequences an are close to zero or zero.

主权项

1. A method for generating a CDMA signal s(t) comprising N components, the method comprises the acts of:
assigning to each of the N components one unique spreading sequence an selected from a set of M spreading sequences with M≧N and modulating symbols dn of each component on the assigned unique spreading sequence an; and combining the N symbols dn each being spread with its own unique spreading sequence an to form a CDMA signal s(t), wherein the assigned spreading sequences an are selected such that all selected pairs within the set of N spreading sequences are orthogonal or very close to orthogonal so that cross-correlation components between all spreading sequences an are close to zero or zero: Rak,an (Δτ)≅0 with the expression for the cross-correlation beingRak,an⁡(Δτ)=1Tint⁢∫0Tint⁢ak⁡(t)⁢an⁡(t-Δτ)⁢⁢ⅆt,and
wherein the symbols dn of the components are selected such that{∏n1∈⁢E1⁢⁢dn1⁡(j1)}·{∏n2∈⁢E2⁢⁢dn2⁡(j2)}=Cstand E1∪E2=[1, 2, . . . , k, . . . , N], wherein Cst is defined as a constant, wherein E1 contains N1 distinct integer indexes, E2 contains N2 distinct integer indexes, being also distinct to the N1 indexes with N1+N2=N, and wherein j1 and j2 correspond to two indexes for two code epochs of duration Tint corresponding to the symbol period Tsymbol, and
wherein all modulated components have the same symbol duration.