Constellation Precoded Multiple Beamforming
Hong Ju Park, Boyu Li, Student Member, IEEE, and Ender Ayanoglu, Fellow, IEEE
Beamforming techniques that employ Singular Value Decomposition (SVD) are commonly used in Multi-Input
Multi-Output (MIMO) wireless communication systems. In the absence of channel coding, when a single symbol is
transmitted, these systems achieve the full diversity order provided by the channel; whereas when multiple symbols
are simultaneously transmitted, this property is lost. When channel coding is employed, full diversity order can
be achieved. For example, when Bit-Interleaved Coded Modulation (BICM) is combined with this technique, full
diversity order of NM in an M × N MIMO channel transmitting S parallel streams is possible, provided a
condition on S and the BICM convolutional code rate is satisfied. In this paper, we present constellation precoded
multiple beamforming which can achieve the full diversity order both with BICM-coded and uncoded SVD systems.
We provide an analytical proof of this property. To reduce the computational complexity of Maximum Likelihood
(ML) decoding in this system, we employ Sphere Decoding (SD). We report an SD technique that reduces the
computational complexity beyond commonly used approaches to SD. This technique achieves several orders of
magnitude reduction in computational complexity not only with respect to conventional ML decoding but also,
with respect to conventional SD.
MIMO systems, SVD, BICMB, constellation precoding, sphere decoding.