One of the major drawbacks of multi-carrier systems is the high peak-to-average power ratio (PAPR) of the transmitted signals. In this paper, the proposed novel low-complexity selective mapping (SLM) schemes are applicable to interleaved-4 orthogonal frequency division multiple access (OFDMA) uplink systems for PAPR reduction. The novel scheme just needs one inverse fast Fourier transform (IFFT) block because that the phases of the transmitted signals in frequency domain are rotated by circular convolution with conversion vectors in time domain. Moreover, a special set of conversion vectors are proposed in novel scheme, which are not only computed with low complexity but also reduce the PAPR effectively. In proposed scheme, different conversion vectors and appropriate subcarriers mapping are picked up for different users. The scheme supplies a practicable low-complexity method for PAPR reduction in interleaved-4 OFDMA uplink systems. Besides, the bit error rate (BER) performance is as good as the SLM scheme.

This doctoral thesis is focused into the area of multicarrier radio communications systems. These systems are perspective for current and incoming mobile communications and wireless networks. Advantages of multicarrier systems like better multipath propagation resistivity are redeemed by some disadvantages. The high peak to average power ratio of transmitted signal belongs to these disadvantages, for its inconvenience for high efficient power amplification. The thesis concerns with peak to average power ratio reduction methods for OFDM systems, that belongs to the most used multicarrier systems. One of the main objectives is the modification of the existing methods with the intention of complexity reduction. Following subject of interest is the analysis of suitable methods combinations possibilities for more significant peak to average power ratio reduction. One part of this thesis is research of influence of these methods on the OFDM signals with different parameters.