Utilization of null subcarriers for PAPR reduction in 3GPP LTE downlink

The multiple access scheme for the long term evolution (LTE) physical layer is based on Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink. The main drawback of OFDMA is the peak-to-average power ratio (PAPR) problem. Dummy sequence insertion (DSI) concept can be an efficient PAPR reduction method for the LTE downlink system because it is very simple to implement and side information is not needed. However, the DSI has to sacrifice a decrease in the transmitted data rate for a large number of dummy subcarriers. In this paper, a novel approach to the DSI concept is proposed for complete application to an LTE system. For effective utilization of physical resources, the unused space of the LTE system is calculated, and dummy subcarriers are inserted into the unused space. Therefore, there is no degradation in transmitted data rate. Simulation results show that the proposed method can reduce PAPR considerably without degradation of bit error rate (BER) performance as a LTE downlink system.