  Contemporary receiver windowed orthogonal frequency division multiplexing
(RW-OFDM) algorithms have limited adjacent channel interference (ACI) rejection
capability under high delay spread and small Fast Fourier Transform (FFT)
sizes. Cyclic prefix (CP) is designed to be longer than the maximum excess
delay (MED) of the channel to accommodate such algorithms in current standards.
The robustness of these algorithms can only be improved against these
conditions by adopting additional extensions in a new backward incompatible
standard. Such extensions would deteriorate the performance of high mobility
vehicular communication systems in particular. In this paper, we present a
low-complexity Hann RW-OFDM scheme that provides resistance against ACI without
requiring any intersymbol interference (ISI)-free redundancies. While this
scheme is backward compatible with current and legacy standards and requires no
changes to the conventionally transmitted signals, it also paves the way
towards future spectrotemporally localized and efficient schemes suitable for
higher mobility vehicular communications. A Hann window effectively rejects
unstructured ACI at the expense of structured and limited intercarrier
interference (ICI) across data carriers. A simple maximum ratio combining
successive interference cancellation (MRC-SIC) receiver is therefore proposed
to resolve this induced ICI and receive symbols transmitted by standard
transmitters currently in use. The computational complexity of the proposed
scheme is comparable to that of contemporary RW-OFDM algorithms, while ACI
rejection and bit-error rate performance is superior in both long and short
delay spreads. Channel estimation using Hann RW-OFDM symbols is also discussed.
