Effect of power amplifier impairments in designing OFDM based wireless communication system

New generation wireless local area network (WLAN) standards (like 802.11a and HIPERLAN/2) use the orthogonal frequency division multiplexing (OFDM) modulation technique because of its ability to offer high data rates while combating the multipath effects encountered in high speed wireless channels. However, OFDM modulated signals have high peak-to-average power ratio (PAPR), and thus can be distorted easily due to the nonlinearity of power amplifiers in transmitters, leading to significant performance loss, large error-vector-magnitude (EVM) high bit error rate (BER) and frame-error-rate (FER). The paper clarifies the relationship between the impairments of the received signal and the nonlinear performance parameters of power amplifiers. Both computer-aided system simulation (using Matlab) and a WLAN test-bed system setup using the Prism V chipset from Intersil are considered. First, a system simulation using computer aided tools characterizes the effect of the number of carriers and modulation size on peak-to-average-power-ratio (PAPR), power amplifiers, receiver EVM, BER and FER.