.
.
X1
X2
XM??“1
COMBINER
FIGURE 5.60 Modified selection combining diversity {SC(M 1)} method.
We begin the performance comparison by presenting the BPSK BER results for the SS/SC diversity
technique for M 1 to 4 antennas. The curves show us that greater than 10 dB of improvement
can be obtained when going from M 1 to M 2 antennas (see Fig. 5.61).
We have discussed and shown the shortcomings of using the SS diversity technique. Figure 5.62
plots the performance of MRC, SS, and SC2 for the case that there are M 3 antennas available in
the receiver. We notice that MRC performs the best while there is a performance gap when viewing
PERFORMANCE IMPROVEMENT TECHNIQUES 273
BPSK SC
1.E??“06
1.E??“05
1.E??“04
1.E??“03
1.E??“02
1.E??“01
0 10 20 30 40 50
Eb/No (dB)
BER
SC (M = 4)
SC (M = 3)
SC (M = 2)
SC (M = 1)
BPSK MRC, SC, and SC2 Comparison
MRC (M = 1)
MRC (M = 2)
MRC (M = 3)
SC (M = 3)
SC2 (M = 3)
1.E??“06
1.E??“05
1.E??“04
1.E??“03
1.E??“02
1.E??“01
0 5 10 15 20 25
Eb/No (dB)
BER
FIGURE 5.61 BPSK BER performance for SC combining.
FIGURE 5.62 BPSK BER performance for MRC, SC, and SC2 combining.
SS of approximately 3 dB. Using the SC2 diversity receiver almost the entire gap in performance can
be omitted with approximately 1 dB performance difference remaining.
Pages:
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449