The underlying waveform has always been a shaping factor for each generationof the cellular networks, such as orthogonal frequency division multiplexing(OFDM) for the 4th generation cellular networks (4G). To meet the diversifiedand pronounced expectations upon the upcoming 5G cellular networks, here wepresent an enabler for flexible waveform configuration, named as filtered-OFDM(f-OFDM). With the conventional OFDM, a unified numerology is applied acrossthe bandwidth provided, balancing among the channel characteristics and theservice requirements, and the spectrum efficiency is limited by the compromisewe made. In contrast, with f-OFDM, the assigned bandwidth is split up intoseveral subbands, and different types of services are accommodated in differentsubbands with the most suitable waveform and numerology, leading to an improvedspectrum utilization. After outlining the general framework of f-OFDM, severalimportant design aspects are also discussed, including filter design and guardtone arrangement. In addition, an extensive comparison among the existing 5Gwaveform candidates is also included to illustrate the advantages of f-OFDM.Our simulations indicate that, in a specific scenario with four distinct typesof services, f-OFDM provides up to 46% of throughput gains over theconventional OFDM scheme.
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