Digital Signal Processing Reference
In-Depth Information
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Independent fading between receive slots if pulse duration is shorter than rx window
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QPSK receiver
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ISSR blocks can have complementary
information about subbands which may
be missing to another ISSR demodulator.
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Find a way to combine the information
of the different ISSR demodulators...
Figure 5.12.
The individual data streams captured from the different receive
slots suffer from independent frequency-selective fading as a result
of isi. Interleaving multiple issr decoders could fill in the gaps
of missing frequency bands and leads to a more than proportional
increase in performance.
that the more pieces are added to the puzzle, the better chances are that the
original transmitted stream can be successfully reconstructed.
The architectural outline of the interleaved issr decoder is obtained from the
original issr decoder as follows. First, suppose that every receive unit in the
pulse-based radio system has its own dedicated issr decoder module, as is
being illustrated by Figure 5.12. Of course, when all issr modules operate
independently from each other, there is no cooperation that might lead to a
more-than-proportional increase of productivity. For example, it is perfectly
possible that two receive branches experience complementary fading chan-
nels, but no sufficient information is available to either of the issr modules to
achieve significant results. The next step is to force the issr modules to share
their information. The interconnection network between the modules is shown
in Figure 5.13. It can be seen that the interleaved issr decoder shares the entire
signal path, starting from the multi-input integrator section. This way, multiple
receive units feed their information into the interleaved issr decoder section,
