Dimensionality reduction for the golden code with worst-case decoding complexity of O(m2)

In this paper we introduce an efficient decoding method which is based on the dimensionality reduction of the sphere decoder search tree for the golden code. A codeword of the golden code has four independent m-QAM data symbols, hence, the required complexity of the exhaustive-search decoder is m4. An efficient implementation of the maximum-likelihood decoder for the golden code with a worst-case complexity is known to be proportional to m2.5. Our motivation is for an efficient decoder with a worst-case complexity of no more than m2.5. In this purpose, we show that our proposed method has m2 complexity in the worst-case with a loss of only 1 dB with respect to optimal decoding.