Spatial stream configuration encoding for wifi

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:

determining, at a first communication device, an allocation of spatial streams for a plurality of second communication devices that are intended receivers of an MU-MIMO transmission by the first communication device;

generating, at the first communication device, a subfield that indicates respective numbers of spatial streams allocated to respective second communication devices among the plurality of second communication devices, wherein generating the subfield is performed 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 corresponds to respective rows of the table, and wherein respective columns of the table correspond to the respective second communication devices, and wherein the subfield is generated to consist of six or fewer bits;

generating, at the first communication device, a multi-user physical layer (PHY) data unit that includes i) a PHY preamble, and ii) the MU-MIMO transmission, including:

generating the PHY preamble to include the subfield, and

generating a PHY data portion that includes the MU-MIMO transmission; and

transmitting, by the first communication device, the PHY data unit.

2. The method of claim 1 , wherein generating the subfield comprises:

generating the subfield according to an encoding that corresponds to subfields that consist of six bits.

3. The method of claim 1 , wherein:

generating the subfield comprises generating the subfield 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

determining the allocation of spatial streams comprises determining an allocation of spatial streams from the subset.

4. The method of claim 3 , wherein:

generating the subfield comprises generating the subfield to consist of five bits.

5. The method of claim 4 , wherein:

generating the subfield comprises generating the subfield 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:

generating the subfield comprises generating the subfield 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:

generating the subfield comprises generating the subfield 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:

generating the subfield comprises generating the subfield to consist of four bits.

9. The method of claim 8 , wherein:

generating the subfield comprises generating the subfield 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 , further comprising:

generating, at the first communication device, respective user fields corresponding to respective second communication devices, including generating the respective user fields to include the subfield that indicates the respective numbers of spatial streams allocated to the respective second communication devices;

wherein generating the PHY preamble to include the subfield includes generating the PHY preamble to include the respective fields arranged within the PHY preamble in an order; and

wherein the respective columns of the table correspond to respective positions of user fields within the PHY preamble.

11. A first communication device, 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:

determine an allocation of spatial streams for a plurality of second communication devices that are intended receivers of an MU-MIMO transmission by the first communication device, and

generate a subfield that indicates respective numbers of spatial streams allocated to respective second communication devices among the plurality of second communication devices, wherein generating the subfield is performed 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 corresponds to respective rows of the table, and wherein respective columns of the table corresponds to the respective second communication devices, and wherein the subfield is generated to consist of six or fewer bits,

generate a multi-user physical layer (PHY) data unit that includes i) a PHY preamble, and ii) the MU-MIMO transmission, including:

generating the PHY preamble to include the subfield, and

generating a PHY data portion that includes the MU-MIMO transmission; and

wherein the one or more IC devices are further configured to control the wireless network interface device to transmit the PHY data unit.

12. The first communication device of claim 11 , wherein the one or more IC devices are further configured to:

generate the subfield according to an encoding that corresponds to subfields that consist of six bits.

13. The first communication device of claim 11 , wherein the one or more IC devices are further configured to:

generate the subfield 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

determine the allocation of spatial streams from the subset.

14. The first communication device of claim 13 , wherein the one or more IC devices are further configured to:

generate the subfield to consist of five bits.

15. The first communication device of claim 14 , wherein the one or more IC devices are further configured to:

generate the subfield 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 communication device of claim 14 , wherein the one or more IC devices are further configured to:

generate the subfield 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 communication device of claim 14 , wherein the one or more IC devices are further configured to:

generate the subfield 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 communication device of claim 13 , wherein the one or more IC devices are further configured to:

generate the subfield to consist of four bits.

19. The first communication device of claim 18 , wherein the one or more IC devices are further configured to:

generate the subfield 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 communication device of claim 11 , wherein the one or more IC devices are configured to:

generate respective user fields corresponding to respective second communication devices, including generating the respective user fields to include the subfield that indicates the respective numbers of spatial streams allocated to the respective second communication devices; and

generate the PHY preamble to include the respective fields arranged within the PHY preamble in an order;

wherein the respective columns of the table correspond to respective positions of user fields within the PHY preamble.