| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 83 === In DS/CDMA systems, the extraction of information from the
received signal passing through noisy environments requires the
synchronization of a pseudonoise (PN) code at the receiver. The
process of synchronization is usually accomplished in two
steps. The first step, called acquisition, is to bring the
local replic of PN code in the receiver into coarse alignment
with the PN code buried in the incoming waveform. Once the
acquisition is achieved, the second step, called tracking,
takes over and continuously maintains fine alignment of PN code
using a feed- back loop. In this thesis, we propose a two-stage
SPRT-based acqui- sition scheme which is more rapid than the
traditional simple SPRT-based acquisiiton scheme from the
search viewpoint. The relation between mean acquisition time
and error (false alarm and missing) probability is examined on
the AWGN channel where other nine equal-power users are treated
as interferences. In addition, we study the tracking loops and
compare two digital DLL schemes from the viewpoint of trade-off
in the performance and hardware complexity.
|
|---|
