{'fraction_non_alphanumeric': 0.015267175572519083, 'fraction_numerical': 0.015267175572519083, 'mean_word_length': 5.084388185654008, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
EFFECT OF SUBCARRIERS ON ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING AT DIFFERENT MOBILE SPEEDS

With recent increase in the demand for mobile communication services, future generations of mobile systems are expected to provide very high data rate transmissions as well as improved quality of service to users within commercial feasibility so as to avoid poor reception which the users are experiencing nowadays. OFDM which is a form of multicarrier transmission is a promising technique capable of providing quality of service at high data rates. In this paper, the OFDM system was developed for orthogonal 32, 64, and 128 subcarriers at different mobile speeds of 30km/h, 60km/h and 120km/h over frequency selective multipath channel. The developed model was simulated using MATLAB application package. OFDM-4QAM modulation format was employed to provide the parallel transmission and the received signal was compared with the transmitted signal to analyze the bit error rate performance of the OFDM system. The results obtained showed that as the number of subcarriers increased from 32, through 64 to 128, the BER increased accordingly for all the mobile speeds considered and the effect is more noticeable at high signal-to-noise ratio. The increase in bit error rate indicates performance degradation. From the results, OFDM system is prone to more CFO as the number of subcarriers is increased due to increase in the complexity of FFT.