Non-Orthogonal Frequency Division Multiple Access

This paper proposes a frequency-domain multiple user access scheme termed non-orthogonal frequency division multiple access (NoFDMA), which maintains the same data rate per user while allowing more users to access via non-orthogonal user overlapping in a given spectral band. User side signal processing follows existing standards with minor modifications. Receiver side operation can jointly process signals from all the users. Computational complexity is investigated for NoFDMA, which shows slightly increased operations than the typical orthogonal frequency division multiple access (OFDMA). Nevertheless, effective spectral efficiency of NoFDMA, considering both raw spectral efficiency and computational complexity, is higher than that of OFDMA. The scalability of the multiple access scheme is flexible via tuning the user overlapping ratio. Simulation reveals that the number of accessed users is doubled using the NoFDMA strategy when compared with the traditional OFDMA scheme over the same spectral resource utilization.