A method for detecting a symbol encoded in one or more received signals, wherein the detected symbol corresponds to a combination of values of n components, n>1, comprises (a) for each of a plurality of different combinations of values of the n components, generating a set of two or more sub-metric values based on the one or more received signals. Each sub-metric is a function of one or more of the n components, and at least one sub-metric is a function of fewer than all n components. The method further comprise (b) detecting the symbol based on the sets of sub-metric values. In another embodiment, an apparatus for detecting a symbol encoded in one or more received signals, wherein the detected symbol corresponds to a combination of values of n components, n>1, comprises (a) means for generating a set of two or more sub-metric values based on the one or more received signals for each of a plurality of different combinations of values of the n components. Each sub-metric is a function of one or more of the n components, and at least one sub-metric is a function of fewer than all n components. The apparatus further comprises (b) means for detecting the symbol based on the sets of sub-metric values.