Dimension Expansion of OFDM System for the Spectral Efficiency Improvement

摘要

In this paper, we analyze the spectral efficiency of three-dimensional orthogonal frequency division multiplexing (3D-OFDM) and multidimensional OFDM (MD-OFDM) systems. 3D-OFDM can improve the performance of the system by mapping symbols to three-dimensional space. Moreover, the expansion of the dimension further improves this property. However, these systems consume additional time resources to expand the dimension, so the benefits of performance improvement can be offset. In this paper, we analyze these characteristics in terms of spectral efficiency. Simulation results show that MD-OFDM can improve system performance by improving symbol error rate (SER) performance as dimension is increased. However, when bit error rate (BER) performance considering time resource and bit efficiency is evaluated, performance is almost unchanged even if dimension is increased. That is, MD-OFDM including 3D-OFDM has spectral efficiency similar to that of conventional OFDM systems in a typical additive white Gaussian noise (AWGN) environment. However, as the dimension is extended, the Euclidean distance between adjacent symbols increases, which could be used for various signal processing such as trellis based channel coding to improve the system.