Suitability of filtering based OFDM for the next generation wireless communications

Abstract

The 4G Long Term Evolution (LTE) cellular communication systems use the popular multicarrier waveformnamed orthogonal frequency division multiplexing (OFDM). Inthe case of huge number of users in 5G scenarios, OFDM maynot be suitable as it is likely to experience spectrum leakage. Inaddition, OFDM will require strict temporal and frequencysynchronization. OFDM also has a high peak to average powerratio (PAPR) causing nonlinearity in the transmitter poweramplifier. These limitations are likely to be overcome by applyingfiltering to the conventional OFDM system. Such a filtering basedOFDM technique is the filter bank multicarrier (FBMC)modulation. The spectral leakage problem in OFDM is reducedin FBMC by the use of pulse shaping principle. Moreover, theusers in FBMC do not need to be synchronized before they gainaccess to the uplink of the communication system. However,FBMC and conventional OFDM have not yet been compared interms of bit error rate (BER) performance in the combinedpresence of Nakagami fading, shadowing, path loss and channelnoise. This thesis presents the analytical expressions on the BER performance of OFDM as well as FBMC systems under Nakagami fading channels. Furthermore, this thesisprovides simulation results on the BERperformance of FBMC and OFDM considering these combinedchannel impairments. The comparison is also done in terms ofPAPR factor and complexity. Results indicate that FBMC and OFDM have comparable BER performance for the case of standalone channel noise. However, FBMC showssignificantly better BER performance than OFDM for thecombined presence of Nakagami fading, shadowing, path loss and channelnoise. On the other hand, for the casesconsidered, FBMC can be slightly inferior to OFDM in terms ofPAPR factor. In addition, FBMC is approximately ten time more complex than OFDM for a given subcarrier number. With these results, FBMC can be an attractive alternative for OFDM in future communication systems.