Superimposed training for OFDM: a peak-to-average power ratio analysis
Orthogonal frequency division multiplexing (OFDM) transmission with superimposed training is considered in this paper. One major disadvantage of OFDM is the significant amplitude fluctuations, i.e., high peak-to-average power ratios (PARs). High PARs require large backoff of the average operating power of a radio-frequency (RF) power amplifier (PA) in order to linearly amplify the signal, thus reducing the dc to RF power conversion efficiency. The PAR of the OFDM signal is examined with superimposed training, and its complementary cumulative distribution function (CCDF) is derived. Achievable lower and upper bounds on the CCDF are also determined. In addition, the PAR change is linked to the effective signal-to-noise ratio (SNR) and thus the bit-error-rate (BER) performance under the fixed dc power constraint. Simulation results are presented to illustrate the proposed PAR and power analysis for OFDM with superimposed training.