designed based on CDMA are suffering from multiple access
interference (MAI) and noise problems. In time varying channel
model, the CDMA systems suffer from complex time varying
channel’s gains plus MAI and noise. A lot of CDMA detectors are
designed to overcome the MAI problem. But these detectors have
complex structures and their performances are affected by the
presence of time varying channel’s gains. This paper gives
proposal for new linear CDMA detector that has the same MAI
cancellation capability as CDMA decorrelator detector but with
simpler structure. The operation of the new detector is based on
the symmetry property of the cross-correlation matrix of CDMA
signatures’ codes. The structure complexity of this new detector
is as simple as matched filter detector structure. The
performance of this new detector is evaluated in the presence of
Nakagami time varying channel’s complex gains. Closed forms of
probability of error for the proposed detector and decorrelator
detector are represented for flat and multipath Nakagami fading
models. Channel phase estimation error effect is included in the
probability of error formulas. Different channel estimators are
used with the proposed detector to overcome the fading
phenomenon. |
