A Research On The PAPR Reduction In OFDM Signals Based On Tone Reservation Scheme

Orthogonal frequency division multiplexing (OFDM) is a promising multicarrier modulation technique, which has many advantages, such as high efficiency spectrum, resistance to multipath fading. OFDM has become a key technology of the next generation communication system. However, the high peak to average power ratio (PAPR) limits the performance of the OFDM system. The PAPR reduction is a hot issue.This paper introduces the research status on the PAPR reduction. We analyze the PAPR reduction schemes from the following aspect, linear or not, transmission rate loss, transmit power increase and the equipment conditions. On this basis, we point out the problems that we make a balance among the system parameters or design a system according to the actual needs.Firstly, this paper proposes a low complexity scheme for PAPR reduction based on selecting efficient peak-canceling signal. The proposed scheme reckons the range of the peak-canceling signal generated by the reserved sub-carriers according to the threshold of power amplifier. The peak-canceling signal will be assorted by the peak value. Moreover, the assorted peak-canceling signal can be used to rapidly reduce the PAPR of the original signal by a search strategy. The simulation results are to verify the effectiveness of proposed scheme with the existing schemes.Secondly, this paper proposes a novel method for PAPR reduction basing on peak canceling signal amplification. We use the IFFT transform to expand the constellation points which can change the PAPR of OFDM signals in the time domain. The proposed method amplifies the peak canceling signal, which is generated by a number of sub-carriers as the same as in traditional tone reservation, to achieve better PAPR repressing effect on need. Therefore, the number of the reserved sub-carriers can be limited and the computing complexity can be reduced while keeping PAPR in the same level as the conventional algorithms. The effectiveness of the proposed algorithm is testified by simulating results.Finally, in order to compare the bit error rate of two proposed schemes, we lead two proposed schemes into an OFDM system simulation.