A first field of a preamble includes a plurality of indications of respective numbers of spatial or space-time streams for respective receivers to enable each receiver among the multiple receivers to determine a respective set of one or more training sequences, in a plurality of training sequences, that corresponds to the receiver. A second field of the preamble includes respective modulation and coding scheme information for the respective receivers. The preamble is generated such that i) the first field is transmitted prior to the plurality of training sequences, and ii) the second field of the preamble is transmitted after the plurality of training sequences are transmitted. A data portion of the multi-user data unit is generated using respective modulation and coding schemes for the respective receivers. The multi-user data unit is transmitted such that data for the respective receivers are transmitted via respective sets of one or more spatial or space-time streams.