New PICR and PAPR reduction scheme for OFDM system using pilot sequences

Abstract

Two major drawbacks of orthogonal frequency division multiplexing (OFDM) are that multicarrier signal exhibit a large peak to average power ratio (PAPR) and is sensitive to carrier frequency offset (CFO). To overcome these drawbacks, many solutions have been proposed and investigated. One of them is the PAPR reduction by using pilot method. Pilot method has many advantages. Also peak interference to carrier ratio (PICR) is effective measure of ICI which is caused by CFO. In this thesis, we utilize this pilot method to reduce PICR of OFDM system. And by using various orthogonal code sets, we can reduce PICR and PAPR simultaneously. In addition to this result, these orthogonal pilot sequences can be employed to estimate channel and eliminate side information by blind detection. Also we show the PAPR reduction capabilities of these orthogonal pilot sequence sets. To reduce computational complexity of our scheme, two methods for selecting pilot sequence are proposed. These methods utilize the PICR and PAPR properties of the pilot sequences and histogram search for selected pilot sequences from all combinations of possible pilot sequences. These two methods reduce computational complexity effectively and improve the PICR and PAPR reduction performances. These results are shown in simulation results