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) a multi-user multiple input, multiple output (MU-MIMO) transmission. The PHY preamble includes a subfield that indicates respective numbers of spatial streams allocated to respective client stations among a plurality of client station that includes the first client station. The subfield has been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, and the subfield consists of six or fewer bits. The first client station decodes the subfield to determine a number of spatial streams allocated to the first client station and 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 a subfield that indicates respective numbers of spatial streams allocated to respective client stations among a plurality of client stations that includes the first client station, wherein the subfield has been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, wherein the encoding corresponds to a table having table elements that indicate respective allocated numbers of spatial streams, wherein respective values of the subfield correspond to respective rows of the table, and wherein respective columns of the table correspond to the respective client stations, and wherein the subfield is generated to consist of six or fewer bits;
decoding, at the first client station, the subfield to determine a number of spatial streams allocated to the first client station; 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 subfield consists of six bits.
3. 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.
4. The method of claim 3 , wherein:
the subfield consists of five bits.
5. The method of claim 4 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to three or more intended receivers when the number of intended receivers is five or more.
6. The method of claim 4 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to more than one intended receiver when the number of intended receivers is six or more.
7. The method of claim 4 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating more than fourteen spatial streams when the number of intended receivers is less than seven.
8. The method of claim 3 , wherein:
the subfield consists of four bits.
9. The method of claim 8 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to two or more intended receivers when the number of intended receivers is three or more.
10. The method of claim 1 , wherein:
the PHY preamble includes a plurality of user fields arranged in an order;
respective user fields in the PHY preamble correspond to respective client stations;
the subfield is included in a user field corresponding to the first client station; and
the respective columns of the table correspond to respective positions of user fields within the PHY preamble.
11. 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 a subfield that indicates respective numbers of spatial streams allocated to respective client stations among a plurality of client stations that includes the first client station, wherein the subfield has been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, wherein the encoding corresponds to a table having table elements that indicate respective allocated numbers of spatial streams, wherein respective values of the subfield correspond to respective rows of the table, and wherein respective columns of the table correspond to the respective client stations, and wherein the subfield is generated to consist of six or fewer bits,
decode the subfield to determine a number of spatial streams allocated to the first client station, and
process the determined number of spatial streams in the MU-MIMO transmission.
12. The first client station of claim 11 , wherein:
the subfield consists of six bits.
13. The first client station of claim 11 , 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 to up to sixteen, and ii) numbers of intended receivers up to eight; and
the determined allocation of spatial streams is from the subset.
14. The first client station of claim 13 , wherein:
the subfield consists of five bits.
15. The first client station of claim 14 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to three or more intended receivers when the number of intended receivers is five or more.
16. The first client station of claim 14 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to more than one intended receiver when the number of intended receivers is six or more.
17. The first client station of claim 14 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating more than fourteen spatial streams when the number of intended receivers is less than seven.
18. The first client station of claim 13 , wherein:
the subfield consists of four bits.
19. The first client station of claim 18 , wherein:
the subfield has been encoded according to an encoding that supports only a subset of all possible combinations that excludes allocating four spatial streams to two or more intended receivers when the number of intended receivers is three or more.
20. The first client station of claim 11 , wherein:
the PHY preamble includes a plurality of user fields arranged in an order;
respective user fields in the PHY preamble correspond to respective client stations;
the subfield is included in a user field corresponding to the first client station; and
the respective columns of the table correspond to respective positions of user fields within the PHY preamble.