Frame padding for wireless communications
Systems and techniques relating to wireless communications are described. A described technique includes obtaining data for a transmission to a wireless communication device(s), including one or more medium access control (MAC) data units that encapsulate data in a physical (PHY) frame, determining a length of a MAC layer pad based on a number of symbols associated with the PHY frame, including, in response to the length of the MAC layer pad being greater than zero, the MAC layer pad in the PHY frame after the one or more MAC data units, determining a length of a PHY layer pad based on remaining available bits in the PHY frame, including, in response to the length of the PHY layer pad being greater than zero, the PHY layer pad in the frame after the MAC layer pad, and transmitting the PHY frame to the wireless communication device(s).
1. A method comprising:
obtaining data for a transmission to a wireless communication device;
including one or more medium access control (MAC) data units in a physical (PHY) frame, wherein the one or more MAC data units encapsulate the data;
determining a length of a MAC layer pad based on a number of symbols associated with the PHY frame;
including, in response to the length of the MAC layer pad being greater than zero, the MAC layer pad in the PHY frame after the one or more MAC data units;
determining a length of a PHY layer pad based on remaining available bits in the PHY frame;
including, in response to the length of the PHY layer pad being greater than zero, the PHY layer pad in the PHY frame after the MAC layer pad; and
transmitting the PHY frame to the wireless communication device.
2. The method of claim 1 , wherein the one or more MAC data units are MAC protocol data units (MPDUs) that are included in the PHY frame in an aggregated MPDU (A-MPDU), wherein including the MAC layer pad in the PHY frame comprises
including one or more padding delimiters after a last non-zero-length A-MPDU subframe of the A-MPDU, wherein each of the one or more padding delimiters are four octets in length, and
including a MAC pad after the one or more padding delimiters, wherein the MAC pad is an integer number of octets in length, which is less than four octets, wherein the MAC layer pad includes the one or more padding delimiters and the MAC pad.
3. The method of claim 2 , wherein the one or more padding delimiters include an end-of-frame flag to inform the wireless communication device to stop receiving a remaining portion of the PHY frame.
4. The method of claim 2 , wherein including the MAC layer pad in the PHY frame comprises including a dword pad in the last non-zero-length A-MPDU subframe of the A-MPDU, wherein the MAC layer pad includes the dword pad.
5. The method of claim 2 , wherein the one or more padding delimiters indicate a MPDU length of zero.
6. The method of claim 1 , further comprising:
making the MAC layer pad reach to a last 8-bit boundary of the PHY frame, exclusive of PHY tail bits in the PHY frame; and
limiting the length of the PHY layer pad to less than 8 bits.
7. The method of claim 1 , further comprising:
making the MAC layer pad reach to the last 32-bit boundary of the PHY frame, exclusive of PHY tail bits in the PHY frame; and
limiting the length of the PHY layer pad to less than 32 bits.
8. The method of claim 1 , further comprising:
including PHY tail bits in the PHY frame after the PHY layer pad.
9. The method of claim 1 , further comprising:
including PHY tail bits in the PHY frame after the MAC layer pad, wherein the PHY layer pad is included after the PHY tail bits.
10. The method of claim 1 , further comprising:
generating, at a MAC layer, the one or more MAC data units and the MAC layer pad, wherein the MAC layer pad extends past a last symbol boundary of the PHY frame; and
reducing, at a PHY layer, the length of the MAC layer pad at a PHY layer to not extend past the last symbol boundary of the PHY frame.
11. The method of claim 1 , wherein
obtaining the data comprises receiving the data for wireless communication devices,
transmitting the PHY frame comprises transmitting spatially steered frames that concurrently provide the data to the wireless communication devices,
a steered frame of the steered frames includes the one or more MAC data units, the MAC layer pad, and the PHY layer pad, and
ends of the steered frames are aligned to have the same length, which is signaled by an omni-directional PHY signaling field that is common to the steered frames.
12. The method of claim 1 , further comprising:
including, in a first PHY signaling field, information to indicate a first length of the PHY frame; and
including, in a second PHY signaling field, information to indicate a second length of the PHY frame.
13. An apparatus comprising:
circuitry to access a wireless communication interface; and
processor electronics configured to
obtain data for a transmission to a wireless communication device via the wireless communication interface,
include one or more medium access control (MAC) data units in a physical (PHY) frame, wherein the one or more MAC data units encapsulate the data,
determine a length of a MAC layer pad based on a number of symbols associated with the PHY frame,
include, in response to the length of the MAC layer pad being greater than zero, the MAC layer pad in the PHY frame after the one or more MAC data units,
determine a length of a PHY layer pad based on remaining available bits in the PHY frame, and
include, in response to the length of the PHY layer pad being greater than zero, the PHY layer pad in the PHY frame after the MAC layer pad.
14. The apparatus of claim 13 , wherein the one or more MAC data units are MAC protocol data units (MPDUs) that are included in the PHY frame in an aggregated MPDU (A-MPDU), and wherein the processor electronics are further configured to
include one or more padding delimiters after a last non-zero-length A-MPDU subframe in the A-MPDU, wherein each of the one or more padding delimiters are four octets in length, and
include a MAC pad after the one or more padding delimiters, wherein the MAC pad is an integer number of octets in length, which is less than four octets, wherein the MAC layer pad includes the one or more padding delimiters and the MAC pad.
15. The apparatus of claim 14 , wherein the one or more padding delimiters include an end-of-frame flag to inform the wireless communication device to stop receiving a remaining portion of the PHY frame.
16. The apparatus of claim 14 , wherein the processor electronics are further configured to include a dword pad in the last non-zero-length A-MPDU subframe of the A-MPDU, wherein the MAC layer pad includes the dword pad.
17. The apparatus of claim 14 , wherein the one or more padding delimiters indicate a MPDU length of zero.
18. The apparatus of claim 13 , wherein the processor electronics are further configured to
make the MAC layer pad reach to a last 8-bit boundary of the PHY frame, exclusive of PHY tail bits in the PHY frame, and
limit the length of the PHY layer pad to less than 8 bits.
19. The apparatus of claim 13 , wherein the processor electronics are further configured to
make the MAC layer pad reach to the last 32-bit boundary of the PHY frame, exclusive of PHY tail bits in the PHY frame, and
limit the length of the PHY layer pad to less than 32 bits.
20. The apparatus of claim 13 , wherein the processor electronics are further configured to
include PHY tail bits in the PHY frame after the PHY layer pad.
21. The apparatus of claim 13 , wherein the processor electronics are further configured to
include PHY tail bits in the PHY frame after the MAC layer pad, wherein the PHY layer pad is included after the PHY tail bits.
22. The apparatus of claim 13 , wherein the processor electronics are further configured to
generate, at a MAC layer, the one or more MAC data units and the MAC layer pad, wherein the MAC layer pad extends past a last symbol boundary of the PHY frame, and
reduce, at a PHY layer, the length of the MAC layer pad at a PHY layer to not extend past the last symbol boundary of the PHY frame.
23. The apparatus of claim 13 , wherein the processor electronics are further configured to
receive the data for wireless communication devices,
transmit spatially steered frames that concurrently provide the data to the wireless communication devices, wherein a steered frame of the steered frames includes the one or more MAC data units, the MAC layer pad, and the PHY layer pad, and wherein ends of the steered frames are aligned to have the same length, which is signaled by an omni-directional PHY signaling field that is common to the steered frames.
24. A system comprising:
circuitry to transmit and receive wireless communication signals; and
processor electronics configured to
obtain data for a transmission to a wireless communication device,
include one or more medium access control (MAC) data units in a physical (PHY) frame, wherein the one or more MAC data units encapsulate the data,
determine a length of a MAC layer pad based on a number of symbols associated with the PHY frame,
include, in response to the length of the MAC layer pad being greater than zero, the MAC layer pad in the PHY frame after the one or more MAC data units,
determine a length of a PHY layer pad based on remaining available bits in the PHY frame, and
include, in response to the length of the PHY layer pad being greater than zero, the PHY layer pad in the PHY frame after the MAC layer pad.
25. The system of claim 24 , wherein the one or more MAC data units are MAC protocol data units (MPDUs) that are included in the PHY frame in an aggregated MPDU (A-MPDU), and wherein the processor electronics are further configured to
include one or more padding delimiters after a last non-zero-length A-MPDU subframe in the A-MPDU, wherein each of the one or more padding delimiters are four octets in length, and
include a MAC pad after the one or more padding delimiters, wherein the MAC pad is an integer number of octets in length, which is less than four octets, wherein the MAC layer pad includes the one or more padding delimiters and the MAC pad.
26. The system of claim 25 , wherein the one or more padding delimiters include an end-of-frame flag to inform the wireless communication device to stop receiving a remaining portion of the PHY frame.
27. The system of claim 26 , wherein the processor electronics are further configured to
receive the data for wireless communication devices,
transmit spatially steered frames that concurrently provide the data to the wireless communication devices, wherein a steered frame of the steered frames includes the one or more MAC data units, the MAC layer pad, and the PHY layer pad, and wherein ends of the steered frames are aligned to have the same length, which is signaled by an omni-directional PHY signaling field that is common to the steered frames.