  The partial interference cancellation (PIC) group decoding has recently been
proposed to deal with the decoding complexity and code rate trade-off on the
basis of space-time block code (STBC) design criterion when full diversity is
achieved. It provides a framework to arrange the rate-complexity-performance
tradeoff by choosing a suitable size of information symbol groups. In this
paper, a simple design of a linear dispersive space-time-frequency (STF) code
is proposed with a design criterion to achieve high rate for
frequency-selective channels in terms of multipath when the PIC group decoding
is applied at receiver. With an appropriate grouping scheme as well as the PIC
group decoding, the proposed STF code is shown to obtain the similar diversity
gain as the maximum likelihood (ML) decoding, namely full-dimensional sphere
decoding, but have a low decoding complexity. It seems as an intermediate
decoding between the ML receiver and zero-forcing (ZF) receiver. The proposed
grouping design criterion for the PIC group decoding to achieve full diversity
deploying the orthogonal-frequency-division multiplexing (OFDM) technique is
also an intermediate condition between the loosest ML full rank criterion of
codewords and the strongest ZF linear independence condition of the column
vectors for the equivalent frequency-selective channel matrix. It can achieves
full diversity with the PIC group decoding for any number of sub-carriers and
the data rate can be made high. Several code design examples are illustrated
for the feasibility of this coding scheme. Simulation results show that the
proposed STF code can well address the rate-performance-complexity tradeoff of
the multiple-input multiple-output orthogonal frequency division multiplexing
(MIMO-OFDM) communication system.
