Patent ID: 8599735

Claim:
A method comprising: at a wireless network device, in a frame comprising a header field that is configured to indicate to recipient devices associated with a multi-user transmission interval during which time, frequency and spatial channel resources are allocated to allow for the transmission of a data frame or simultaneous transmission of corresponding ones of a plurality of data frames to respective recipient devices: allocating a first portion of a plurality of group identifiers for multi-user groups for sending multi-user transmissions during the multi-user transmission interval and a second portion of the plurality of group identifiers for multicast groups for sending multicast transmissions during the multi-user transmission interval, wherein the allocating includes determining which of the recipient devices are capable of decoding the header field to obtain and interpret the group identification information included in the header field, and not assigning to a group any recipient devices that are not capable of decoding the header field to obtain and interpret the group identification information included in the header field; generating group identification information comprising a group identifier selected from the plurality of group identifiers; and wirelessly transmitting the group identification information that indicates a group of recipient devices which are to receive a transmission during the multi-user transmission interval; and wirelessly transmitting data from the wireless network device for a multicast transmission during the multi-user transmission interval that follows the header field, the multicast transmission intended for a group of recipient devices that are members of a multicast group corresponding to the group identification information contained in the header field.