Modified PTS with FECs for PAPR Reduction in MIMO-OFDM System with Different Subblocks and Subcarriers
Multiple input multiple output orthogonal frequency division
multiplexing (MIMO-OFDM) systems have been proposed in the
recent past for providing high data-rate services over wireless
channels. When combined with space time coding it provides the
advantages of space-time coding and OFDM, resulting in a
spectrally efficient wideband communication system. However,
MIMO OFDM systems suffer with the problem of inherent high
peak-to-average power ratio (PAPR) due to the intersymbol
interference between the subcarriers. In order to obtain optimal
PAPR reduction using the partial transmitted sequence (PTS), the
total search for the number of subblocks and the rotation factors
must be accomplished. As the number of subblocks and rotation
factors increases, PAPR reduction improves. The number of
calculation increases as the number of subblocks increases, such
that complexity increases exponentially and the process delay
occurs simultaneously. In this paper, a generalised framework for
PAPR reduction for MIMO OFDM systems based on modified
PTS using forward error-correcting codes (FECs) such as Turbo
codes and Golay codes are employed. PAPR reduction is jointly
optimised in both the real and imaginary part by use of fast
Fourier transform (FFT) algorithm in the modified PTS which
can be utilized for finding the optimum phase weighting factors,
and can achieve the lower PAPR and computational complexity
of MIMO OFDM systems. The simulation results show that the
combined FEC with modified PTS technique significantly
provides better PAPR reduction with reduced computational
complexity compared to original PTS technique in the MIMOOFDM
systems.
Keywords: MIMO, OFDM, PTS, STBC, Turbo code, Golay Codes, Reed-Muller Codes and PAPR
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