Performance evaluation of DS-CDMA systems on multipath propagation channels with multilevel spreading sequences and RAKE receivers

Enhanced rake receivers for chaos-based DS-CDMA

“…As two of the three components of the correlate-and-dump output are well approximated by Gaussians, the average error probability is given by in which, following an established path [18] we have substituted average variances of disturbing terms to estimate the average . To give an analytical expression note that, in general for any constants , so that…”

“…The trajectory is quantized by a function which produces a sequence of complex symbols that are nothing but the th complex roots of 1 (see e.g., [18]). Here, we assume that such a quantization is such that is an integer multiple of and that all the points in the interval are mapped by to the same complex symbols so that .…”

A Framework for Performance Analysis of TH– UWB Communications

“…For a given set of hopping codes assigned to the various transmitters, the average in (17) involves only the discrete random time-shift (asynchronism) m r,k , so that: (19) and where p m r,k (m r,k ) denotes the pdf of m r,k and E m r,k s H 1 (m r,k ) denotes its average. Since the TH-to-DS mapping allows to deal with binary codes, i.e.…”

“…In fact, multi-level sequences seem to have been proposed in a very restricted number of contributions in the frame of Direct Sequence Code Division Multiple Access, DS-CDMA, (see e.g. [17], [18]), due to theirs limited advantages over binary codes, and with some non completely explored aspects. Moving from the theoretic foundation proposed in [21], [22], [24], we came up [1] with a convincing frame for consistent extension of such sequences, generating polynomials and related shift register structures.…”