An improved and efficient detection scheme for V-BLAST systems with QAM modulation

Abstract

The paper proposed an improved Ordered Successive Interference Cancellation (OSIC) detection scheme for V-BLAST systems with square/rectangular Quadrature Amplitude Modulation (QAM) modulation. It utilizes an equivalent real-valued vector expression of relationship between transmit signals and received signals, exploits the constellation’s product-form structure and can eventually make the order, in which components of the transmit signals vector are extracted, more “optimal” in some sense. Thereby, it can offer an improved error probability as compared to the conventional OSIC detection scheme. In addition, the paper also proposes an efficient projection algorithm to calculate nulling vectors in a simple recursive fashion in order to avoid the vast increase of complexity, which is due to the fact that the original complex N-dimensional data vector and M × N channel matrix are transformed into a real 2N-dimensional data vector and a real 2M × 2N channel matrix respectively. A scrutinous complexity analysis shows that the complexity increases by only 33% as compared to the conventional scheme.