Throughput Analysis of Cognitive Radio Systems using Monte-Carlo Simulation

Orthogonal frequency division multiplexing (OFDM) is becoming the chosen modulation technique for wireless communications. OFDM can provide large data rates with sufficient robustness to radio channel impairments. Many research centers in the world have specialized teams working in the optimization of OFDM for countless applications. The transmit signals in an OFDM system can have high peak value s in the time domain since many subcarrier components are added via an IFFT operation. Therefore, OFDM systems are known to have a high PAPR (Peak -to-Average Power Ratio), compared with single-carrier systems. In fact, the high PAPR is one of the most detrimental aspects in the OFDM system, as it decreases the SQNR (Signal -to-Quantization Noise Ratio) of ADC (Analog-to-Digital Converter) and DAC (Digital- to-Analog Converter) while degrading the efficiency of the power amplier in the transmitter. The PAPR problem is more important in the uplink since the efficiency of power amplier is critical due to the limited batter y power in a mobile terminal. This research paper discusses several techniques that are being used to reduce the PAPR in an OFDM system