A nonzero intermediate frequency likelihood acquisition scheme forCDMA system

摘要

A nonzero intermediate frequency (IF) likelihood acquisitionscheme for PN codes is introduced in this paper. The received signal isfirst downconverted to IF, and then direct sampled in IF using a 1-bitA/D converter. After the digitalization, the sampled data is detectedusing a hybrid likelihood acquisition scheme. Using this structure,problems, due to large noise figure of the analog mixer or activefilters or due to amplitude and phase imbalance between low-frequencyin-phase and quadrature-phase channels, can be avoided. An algorithmwhich allows easy implementation of the acquisition scheme is alsoderived. The performance and algorithm are verified by computersimulation