Designing Equalizers Based on Linear Baseband Models of
Direct-Sequence Code-Division Multiple Access Systems
Internal Report UPTEC 96025R, Dept. of Technology,
Over the years, many detectors have been proposed for
systems employing Code-Division Multiple Access (CDMA).
Here we develop a framework for the design of such detectors,
(especially multiuser detectors). We also derive such a detector,
the fractionally spaced multivariable DFE.
In this report, we show how the entire process of transmission
and reception in a DS-CDMA system, including the spreading,
can be described as a tapped delay line with multiple inputs and
a single output.
We then demonstrate how this model can be used to design a
fractionally spaced decision feedback equalizer with a single
input and multiple outputs. In the proposed approach, long codes
can be used and channel estimation can be performed in an efficient
way. The suggested detector is near-far resistant and the capacity
of the system is not limited by intracell interference.
Monte Carlo simulations are conducted to demonstrate
the superiority of the proposed approach as compared to the
conventional detector. The simulation scenario constitutes a
heavily loaded system with multipath.
Situations with and without power control are considered.
- Related publications:
in IEEE ICUPC'96.
at the Swedish Radio Conference 1996.
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