Patent ID: 7804762

Claim:
A method comprising: identifying a plurality of orthogonal sets of user devices in a cell of a wireless network, wherein each orthogonal set in said plurality of orthogonal sets includes multiple user devices that can be transmitted to concurrently by an access point using different antenna beams in a spatial division multiple access (SDMA) mode of operation; selecting an orthogonal set from the plurality of orthogonal sets for use in transmitting data to the corresponding user devices based on a predetermined selection criterion; and initiating, after selecting, an SDMA exchange for the selected orthogonal set; wherein initiating an SDMA exchange includes: simultaneously transmitting data to user devices in said selected orthogonal set using corresponding antenna beams; and transmitting an acknowledgement (ACK) request to each user device in said selected orthogonal set after said data has been transmitted, wherein transmitting an ACK request includes transmitting a single multi-user ACK request using an antenna beam that encompasses all of said user devices in said selected orthogonal set, said single multi-user ACK request including time information indicative of a time at which each user device in said selected orthogonal set is to respond to said single multi-user ACK request, wherein said time information is determined based upon a predicted resolvability of signals received from said user devices within said selected orthogonal set.