Because each golden code codeword conveys four information symbols from an -ary QAM alphabet, the complexity of an exhaustive-search decoder is proportional to 4 . In this paper we prove that the golden code is fast-decodable, meaning that maximum-likelihood decoding is possible with a worst-case complexity proportional to only 2.5 . The golden code retains its fast-decodable property regardless of whether the channel varies with time. We also present an efficient implementation of a fast maximum-likelihood decoder that exhibits a low average complexity.
Mohanned O. Sinnokrot, John R. Barry