Digital Communication Receivers: Synchronization, Channel Estimation, and Signal ProcessingHeinrich Meyr, Marc Moeneclaey, Stefan A... 15.1 Non-Data-Aided NDA Selective Fading Channel Es
Trang 1Digital Communication Receivers: Synchronization, Channel Estimation, and Signal Processing
Heinrich Meyr, Marc Moeneclaey, Stefan A Fechtel Copyright 1998 John Wiley & Sons, Inc Print ISBN 0-471-50275-8 Online ISBN 0-471-20057-3
Trang 915.1 Non-Data-Aided (NDA) Selective Fading Channel Estimation and Detection 773
and every symbol hypothesis ak-1 By virtue of whitening matched prefiltering (WMF, previous chapter), only very few - in all of the simulation examples be- low, between M=l and 4 - contending symbol hypotheses need to be kept by the equalizer for quasi-optimal detection The number of NDA parameter sync units working on the corresponding survivors is reduced accordingly, i.e., only M chan- nel estimates (and parameter sets derived from the channel estimates) remain to
be generated Estimating the channel - or any other parameters of interest - in such a survivor-dependent fashion is a rather general concept sometimes referred
to generate all of the simulation results reported below, features a detection path comprising matched filtering, decimation to symbol rate, whitening filtering, M algorithm equalization, and (not shown in the figure) differential decoding in order
to resolve phase slips The parameter synchronization path includes DD channel estimation, parameter computation from the channel estimate, and a unit referred
to as timing slip control As explained below, this unit is necessary to prevent
parameter synchronization
Figure 15-5 M-PSK Receiver with DD Selective Fading Channel Estimation