Abstract: This paper presents a single correlator RAKE receiver for direct sequence code division multiple access (DS-CDMA) systems. In conventional RAKE receivers, multiple correlators are used to despread the multipath signals and then to align and combine those signals in a later stage before making a bit decision. The simplified receiver structure presented here uses a single correlator and single code sequence generator to recover the multipaths. Modified Walsh- Hadamard codes are used here for data spreading that provides better uncorrelation properties for the multipath signals. The main advantage of this receiver structure is that it requires only a single correlator and a code generator in contrary to the conventional RAKE receiver concept with multiple correlators. It is shown in results that the proposed receiver achieves better bit error rates in comparison with the conventional one for more than one multipaths.
Abstract: Linear Discrimination Analysis (LDA) is a linear
solution for classification of two classes. In this paper, we propose a
variant LDA method for multi-class problem which redefines the
between class and within class scatter matrices by incorporating a
weight function into each of them. The aim is to separate classes as
much as possible in a situation that one class is well separated from
other classes, incidentally, that class must have a little influence on
classification. It has been suggested to alleviate influence of classes
that are well separated by adding a weight into between class scatter
matrix and within class scatter matrix. To obtain a simple and
effective weight function, ordinary LDA between every two classes
has been used in order to find Fisher discrimination value and passed
it as an input into two weight functions and redefined between class
and within class scatter matrices. Experimental results showed that
our new LDA method improved classification rate, on glass, iris and
wine datasets, in comparison to different versions of LDA.