AN EFFICIENT POWER REDUCTION TECHNIQUE IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM USING TONE RESERVATION

Abstract

In a basic communication system, the data’s are modulated onto a single carrier frequency. The available bandwidth is then totally occupied by each symbol. This kind of system can lead to Inter-Symbol-Interference (ISI) in case of frequency selective fading. The basic idea of Orthogonal Frequency Division Multiplexing (OFDM) is to divide the available spectrum into several orthogonal sub channels so that each narrowband sub channel experiences almost flat fading. In OFDM system, orthogonally placed sub-carriers are used to carry the data from the transmitter end to the receiver end. However, the major challenging issue is to reduce PAPR and Bit Error Rate (BER). The reduction algorithm for OFDM signals is presented in this project using convex optimization technique along with Tone Reservation (TR). Tone reservation uses other unused or reserved tones to design a peak-cancelling signal that lowers the PAR of a transmit OFDM block. Similarly it lowers the bit error rate. In contrast to previous methods, the tone reservation with convex optimization implies a very quick convergence of minimum-PAR and bit error rate solution at a lower computational cost. Also the effects of oversampling at l = 1,2,4,8 on the performance of proposed OFDM system is discussed.