E??“04
1.E??“03
1.E??“02
1.E??“01
6 8 10 12 14 16 18 20 22
Eb/No (dB)
BER
AWGN Theory
Fading Theory
2-Ray Theory
384 kbps, 5CP, fd = 20 Hz
384 kbps, 8DP, fd = 20 Hz
FIGURE 7.74 Two-ray frequency-selective fading BER performance with Doppler spread (200 Hz).
WCDMA 384 kbps Simulation 2 Ray
1.E??“04
1.E??“03
1.E??“02
1.E??“01
6 8 10 12 14 16 18 20 22
Eb/No (dB)
BER
Fading Theory
2-Ray Theory
384 kbps, 5CP, fd = 200 Hz
384 kbps, 5CP, fd = 300 Hz
384 kbps, 8DP, fd = 200 Hz
that the insertion of the second ray leads to interpath interference (IPI) that is not negligible for the
low SF of interest. We will discuss the impact of IPI on the RAKE output in the latter sections.
The maximum Doppler spread was increased to 200 Hz, and once again, we can clearly see the
degradation of the second technique (DP) to be larger than the first technique (CP). We have also plotted
the performance of the first technique, where the maximum Doppler spread was further increased
to 300 Hz.
To summarize the observations, we begin by restating that two causal CE techniques were compared.
Generally speaking, these techniques seem to break down at high Doppler spreads. Moreover,
assuming a time-invariant channel in a fast-fading channel is incorrect, but acceptable at the very low
Doppler spread values.
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