Spectrally Efficient Frequency Division Multiplexing in LTE Downlink

Abstract: Spectral efficiency is a key design issue for all wireless communication systems. Orthogonal frequency division multiplexing (OFDM) is a very well-known technique for efficient data transmission over many carriers overlapped in frequency. The 3GPP has chosen the OFDM as the radio access technology due to its simple implementation in receiver and spectral efficiency. To enhance system�s data rate a proposed system of using SEFDM instead of OFDM for LTE downlink air interface. SEFDM systems propose bandwidth savings when compared to OFDM systems by multiplexing multiple non orthogonal overlapping carriers. Two detection methods were used: Efficient Sphere Decoder (ESD) and ESD with Iterative Cancellation (IC). The efficacy of the proposed design is shown through detailed simulation of systems with different bandwidth compression values. The ESD-IC decoder proposed produces a very good result. The system is able to produce efficiency gains of up to 25% while maintain performance near to an OFDM. The performances of two systems (OFDM and SEFDM) were compared in terms of performance and throughput with fixing all the other parameters.

Keywords: LTE, OFDM, BCF, SEFDM, ESD, ESD_IC.