Next the NEC performance plots are shown below. Here we have used the Rician channel model
with Rician factor, K 10 dB and a Doppler spread of 60 Hz. Here we see using the single-error correction
receiver produces approximately 1 dB of gain at BER 1E-4 (see Fig. 4.41).
210 CHAPTER FOUR
Diff. Detector & 1NEC performance Comparison
Rician Channel Model
1.0E??“5
0.0E??“4
1.0E??“3
1.0E??“2
1.0E??“1
4 6 8 18 16 14 12 10
Eb/No (dB)
BER
Diff. Detect.
1NEC
FIGURE 4.41 Single-error correcting NEC receiver performance in Rician fading
channel model.
If we were to focus on the MLDD performance improvement for DQPSK and 8DPSK modulation
schemes, we would want to show the following two figures (Figs. 4.42 and 4.43).
First the BER performance for DQPSK is presented. The results show when increasing the observation
window from 2 symbols (which is already the case for the differential detector) to 3 symbols
MLDD Performance for DQPSK in AWGN
1.E??“6
1.E??“5
1.E??“4
1.E??“3
1.E??“2
1.E??“1
5 7 9 10 11 12 13
Eb/No (dB)
BER
MLDD (5 Sym)
MLDD
Pb(DQPSK)-DD
2 Symbols
3 Symbols
5 Symbols
6 8
FIGURE 4.42 MLDD detector performance for DQPSK in an AWGN channel.
(for MLDD) there is approximately a gain of 1 dB.
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