A method for communication includes receiving a spatially-multiplexed signal using multiple receivers to produce multiple respective received signals. The spatially-multiplexed signal includes multiple simultaneously-transmitted symbols, which are selected from respective sets of constellation symbols, each constellation symbol representing a respective set of values of a group of data bits.Combinations of the constellation symbols are traversed iteratively. Each combination includes one constellation symbol from each of the sets of the constellation symbols and represents N data bits. The traversed combinations are searched for a combination that matches the received signals.During traversal of the combinations, at least 2N measures of likelihood regarding the values of the data bits represented by each traversed combination are accumulated. The accumulated measures of likelihood are processed to produce soft bit metrics. The values of the data bits carried by the multiple transmitted symbols are reconstructed responsively to the soft bit metrics.