Performance Evaluation of Different PSK Schemes in an OFDM System Using a Real Time Image

Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation scheme that combines a large number of low data rate carriers into a composite high data communication system. Unlike in many other modulation techniques, the addition of cyclic prefix to the OFDM symbols combats the intersymbol interference and the orthogonality of the carriers allows it to combat Intercarrier interference in the OFDM modulation technique. Acknowledging these advantages, OFDM is the most preferred modulation technique in most of the next-generation wireless communication networks for transmitting many forms of digital data with higher efficiency. To evaluate the functionality and overall performance of an OFDM system, a digital data corresponding to a two-dimensional gray-scale image is used as a test signal. This paper aims at evaluating the performance of various phase shift keying (PSK) techniques taking a real time image as a test sample, which is converted into a form suitable for OFDM transmission, then transmitting the converted OFDM signal over the additive white Gaussian noise channel over various signal to noise ratio values. The performance is evaluated by comparing the clarity of the received image after demodulation with the original image, bit error rate (BER) Vs SNR, transmission and reception times of various PSK schemes (BPSK, QPSK,16-PSK and 256-PSK). The BER offered by BPSK is the least while transmission times offered by 256-PSK is the least. Along with these, different PSK schemes are compared by changing the clipping amplitude that is done to combat nonlinearities due to high peak to average power ratio.