Spatial stream configuration encoding for WiFi
A first client station receives a multi-user physical layer (PHY) data unit from an access point. The multi-user PHY data unit includes i) a PHY preamble, and ii) an MU-MIMO transmission. The PHY preamble includes respective subfields that indicate respective numbers of spatial streams allocated to respective client stations. The respective subfields have been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers. The respective subfields are arranged in the PHY preamble according to an order. The first client station determines a position of a particular subfield corresponding to the first client station within the order, and uses the position of the particular subfield to decodes the particular subfield to determine a number of spatial streams allocated to the first client station. The first client station processes the determined number of spatial streams in the MU-MIMO transmission.
1 . A method for communicating in a wireless local area network (WLAN) that utilizes multi-user multiple input, multiple output (MU-MIMO), the method comprising:
receiving, at a first client station, a multi-user physical layer (PHY) data unit from an access point, the multi-user PHY data unit including i) a PHY preamble, and ii) an MU-MIMO transmission, wherein the PHY preamble includes respective subfields that indicate respective numbers of spatial streams allocated to respective client stations among a plurality of client stations that includes the first client station, wherein the respective subfields have been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, wherein the respective subfields are arranged in the PHY preamble according to an order;
determining, at the first client station, a position of a particular subfield corresponding to the first client station within the order;
decoding, at the first client station, the particular subfield to determine a number of spatial streams allocated to the first client station, including decoding the particular subfield using the position of the particular subfield within the order; and
processing, by the first client station, the determined number of spatial streams in the MU-MIMO transmission.
2 . The method of claim 1 , wherein:
the PHY preamble includes a plurality of user fields arranged in the order;
respective user fields in the PHY preamble correspond to respective client stations; and
the respective subfields are included in respective user fields.
3 . The method of claim 2 , wherein determining the position of the particular subfield within the order comprises:
determining, at the first client station, that a particular user field, amongst the respective user fields, corresponds to the first client station; and
determining, at the first client station, the position of the particular subfield within the order based on a position of the particular user field amongst the respective user fields.
4 . The method of claim 3 , wherein determining that the particular user field corresponds to the first client station comprises:
identifying, at the first client station, a station identifier within the particular user field that corresponds to the first client station.
5 . The method of claim 1 , wherein the subfield consists of six bits.
6 . The method of claim 1 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations of i) numbers of spatial streams up to sixteen, and ii) numbers of intended receivers up to eight; and
the determined number of spatial streams is from the subset.
7 . The method of claim 1 , wherein:
the encoding corresponds to a table having table elements that indicate respective allocated numbers of spatial streams;
respective rows of the table correspond to respective values of the subfields; and
respective columns of the table correspond to the respective client stations.
8 . The method of claim 7 , wherein:
the respective columns of the table correspond to respective positions of subfields within the order.
9 . A first client station, comprising:
a wireless network interface device that is configured to communicate in a wireless local area network (WLAN) using multi-user multiple input, multiple output (MU-MIMO), the wireless network interface device having one or more integrated circuit (IC) devices configured to:
receive a multi-user physical layer (PHY) data unit from an access point, the multi-user PHY data unit including i) a PHY preamble, and ii) an MU-MIMO transmission, wherein the PHY preamble includes respective subfields that indicate respective numbers of spatial streams allocated to respective client stations among a plurality of client stations that includes the first client station, wherein the respective subfields have been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, wherein the respective subfields are arranged in the PHY preamble according to an order,
determine a position of a particular subfield corresponding to the first client station within the order,
decode the particular subfield to determine a number of spatial streams allocated to the first client station, including decoding the particular subfield using the position of the particular subfield within the order, and
process the determined number of spatial streams in the MU-MIMO transmission.
10 . The first client station of claim 9 , wherein:
the PHY preamble includes a plurality of user fields arranged in the order;
respective user fields in the PHY preamble correspond to respective client stations; and
the respective subfields are included in respective user fields.
11 . The first client station of claim 10 , wherein the one or more IC devices configured to:
determine that a particular user field, amongst the respective user fields, corresponds to the first client station; and
determine the position of the particular subfield within the order based on a position of the particular user field amongst the respective user fields.
12 . The first client station of claim 11 , wherein the one or more IC devices configured to:
determine the position of the particular user field amongst the respective user fields based on identifying a station identifier within the particular user field that corresponds to the first client station.
13 . The first client station of claim 9 , wherein the subfield consists of six bits.
14 . The first client station of claim 9 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations of i) numbers of spatial streams up to sixteen, and ii) numbers of intended receivers up to eight; and
the determined number of spatial streams is from the subset.
15 . The first client station of claim 9 , wherein:
the encoding corresponds to a table having table elements that indicate respective allocated numbers of spatial streams;
respective rows of the table correspond to respective values of the subfields; and
respective columns of the table correspond to the respective client stations.
16 . The first client station of claim 9 , wherein:
the respective columns of the table correspond to respective positions of user fields within the PHY preamble.
17 . The first client station of claim 9 , wherein:
the wireless network interface device includes one or more transceivers implemented at least partially using the one or more IC devices.
18 . The first client station of claim 17 , further comprising:
a host processor coupled to the wireless network interface device.
19 . The first client station of claim 18 , further comprising:
one or more antennas coupled to the one or more transceivers.