Abstract

The demand for high-speed mobile wireless communications is rapidly growing.
OFDM technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems of the near future. This work presents an investigation into methods for maximizing the spectral efficiency of Orthogonal Frequency Division Multiplexing (OFDM) systems.
The current standards such as IEEE 802.11a in USA and Hyper LAN/2 in Europe are all based on OFDM in their PHY layer. First, we show that in order to be free of both inter channel interference and inter block interference, wireless OFDM has to occupy a bandwidth wider than the Nyquist rate and use insufficient statistics in symbol demodulation. Thus, the conventional OFDM gains computational efficiency by using discrete Fourier transform (DFT) in demodulation at the cost of low efficiency of bandwidth usage and degradation in symbol error performance.