Next Generation Reference Signal Design Using Non-Orthogonal Space-Time Codes

In this paper, we propose a Reference Signal (RS) framework potentially for next generation wireless systems, which targets to systematical RS construction with nonorthogonal Space-Time Code (STC) designs. In particular, we embed parametrized non-orthogonal STCs into the RS design, by exploiting the properties of so-called ABBA STCs or its diagonal variants, where the diagonality is imposed by use of appropriate precoding and postcoding. The transformations of the ABBA coding vectors can be resolved at the receiver. The transformed matrices are used to enhance channel estimation quality with the aid of inherent power gain, self-interference mitigation, and diversity gain. The proposed framework can be flexibly integrated to existing RS sequences, defined in 5G New Radio (NR). In effect, this leads to parameterizable code space and controllable self-interference. The proposed RS construction can be easily extended to support <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2^{M} \times 2^{M}$</tex> STC systems for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M \geq 2$</tex>, and can be used to track the channel response with up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2^{M}$</tex> spatial links in parallel.