Blind Hopping Phase Estimator in Frequency-Hopped FM and BFSK Systems

A Hybrid PAPR Reduction Scheme for Optical Wireless OFDM Communication Systems

“…An alternative approach is to use a simpler type of prcoding that consists of multiplying the signal by a matrix to reduce the autocorrelation of the input sequence and thus the signal's PAPR. The precoding matrices can be based on the Hadamard transform or the discrete cosine transform [9]- [10]. The work in [11] proposed the using of trellis coding to reduce the large negative peaks of the bipolar signal.…”

“…The LED input signal x LED is obtained from x pts after clipping process further reduce the PAPR. Let x clip denote the clipped version of x pts , which is expressed as The clipping ratio (CR) is defined as the clipping level normalized by the RMS value σ, variance of OFDM signal, such that [24] σ c CR = (10) It is worth to mention that, a higher CR corresponds a higher threshold, and hence, the effect of PAPR reduction gets worse, and vise versa. According to the cumulative signal processing and the modifications proposed, the resulting ACO-OFDM signal is ready to be transmitted through LED and would enable the reduction of PAPR significantly as well as improves the BER performance.…”