Performance Improvement Techniques for OFDM system using Software Defined Radio

Improved spectral and energy efficiency are two key requirements for the next generation (5G) wireless communication systems. The inefficiency and non-linearity of traditional power amplifiers (PA) pose significant challenges to meet these requirements, especially for multicarrier modulation signals with high peak to average power ratio (PAPR). Orthogonal frequency division multiplexing (OFDM) is currently the most widely used multi carrier modulation technique; it has been adopted in many wireless communication standards including IEEE 802.11, 802.16, 3GPP Long Term Evolution and WiMAX. When a high PAPR signal process through a nonlinear power amplifier (PA), intermodulation distortion is generated, creating out-of-band emission that can interfere with other transmission in adjacent bands. In addition, in-band distortion, which degrades the bit error rate performance, occurs. Hence, I have addressed these problems by employing four different PAPR reduction techniques such as Phase modulation, Rail clipping, Sample and Hold approach and Threshold methods based on amplitude clipping. For practical proof of the proposed concepts, I have chosen software defined radio as an experimental setup that employs USRP N210 as hardware and GNU Radio as software.