Evolution from symbol-level space-time coded MIMO to chip-level space-time coded MIMO: A review

Space-time coded multiple-input multiple-output (MIMO) technology is an important technique that improves the performance of wireless communication systems significantly without consuming bandwidth resource. This paper first discusses the characteristics and limitations of traditional symbol-level space-time coding schemes, which work largely on the basis of an assumption that signals are sent to a block-fading channel. Therefore, the symbol-level space-time coding schemes rely on symbol-level signal processing. Taking advantage of orthogonal complementary codes, we propose a novel MIMO scheme, in this paper, based on chip-level space-time coding that is different from the traditional symbol-level space-time coding. With the help of space-time-frequency complementary coding and multicarrier modem, the proposed scheme is able to achieve multipath interference-free and multiuser interference-free communications with simple a correlator detector. The proposed chip-level space-time coded MIMO works well even in a fast fading channel in addition to its flexibility to achieve diversity and multiplexing gains simultaneously in varying channel environments.