LDPC-Based Space-Time Coded OFDM Systems
In this section we first examine the STC-OFDM system
performance in correlated fading channels in terms of channel capacity and
pairwise error probability (PEP). In [363], information-theoretic aspects
of a two-ray propagation fading channel are studied. In [122, 478], the channel capacity of a
multiple-antenna system in fading channels is investigated; and in [39], the limiting
performance of a multiple-antenna system in block-fading channels is studied,
under the assumption that the fading channels are uncorrelated and the channel
state information is known to both the transmitter and the receiver. Here, we
analyze the channel capacity of a multiple-antenna OFDM system over correlated
frequency- and time-selective fading channels, assuming that the CSI is known
only to the receiver. As a promising coding scheme to approach the channel
capacity, STC is employed as the channel code in this system. The pairwise error
probability analysis of the STC-OFDM system is also given. Moreover, based on
the analysis of the channel capacity and the PEP, some STC design principles for
the system under consideration are suggested. Since the STC based on
state-of-the-art low-density parity-check (LDPC) codes [127, 302, 303, 416, 417] turns out to be a good candidate
to meet these design principles, we then discuss an LDPC-based STC-OFDM system
and a turbo receiver for this system. The materials in this section first
appeared in [293].
Note that a simple space-time trellis code design method for OFDM systems is
given in [289, 291].
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