Information Technology Reference
In-Depth Information
4.1 The OFDM Signal Amplitude Comparison
The sampling points are 256, and modulation type is QPSK. The OFDM signals are
compared by the original OFDM, TCM algorithm, LCT algorithm and the proposed
hybrid algorithm.
From Fig.1, Fig.2, Fig.3 and Fig.4, we can observe that OFDM signal has higher
signal amplitude and has reduced significantly by using the hybrid algorithm as com-
pared with TCM and LCT algorithms.
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
50
100
150
200
250
300
Sample Number
Fig. 4.
The amplitude of the OFDM symbol with the combining algorithm
4.2 CCDF Comparison of the Algorithms
The simulation conditions are assumed that the signal type is QPSK and the number of
subcarriers is 64. The OFDM signal is oversampled and the factor is 4. In this system,
100000 randomly symbols are generated. Figure 5 shows the PAPR performance of the
conventional OFDM, TCM algorithm, LCT algorithm and hybrid algorithm. From
Figure 5, it is clear that the threshold of hybrid algorithm, LCT algorithm and TCM
algorithm are 4.2dB, 4.5dB and 6.5dB respectively, when
CCDF
=
. So the per-
formance of hybrid algorithm is better than TCM algorithm and LCT algorithm. The
hybrid algorithm can effectively reduce the peak to average power ratio.
3
10
0
10
10
-1
-2
10
10
-3
Init ial
LCT
TCM
t
he mixed
10
-4
10
-5
0
2
4
6
8
10
12
PAPR(dB)
Fig. 5.
Comparison of PAPR performance
Search WWH ::
Custom Search