Wireless apparatus for high-efficiency (HE) communication with additional subcarriers
Embodiments of an access point and method for high-efficiency WLAN (HEW) communication are generally described herein. In some embodiments, the access point may be configured to operate as a master station and may configure an HEW frame to include a legacy signal field (L-SIG), an HEW signal field (HEW SIG-A) following the L-SIG, and one or more HEW fields following the HEW SIG-A. The L-SIG may be configured for transmission using a legacy number of data subcarriers, a legacy number of pilot subcarriers and a number of additional reference subcarriers modulated with a known reference sequence. At least one symbol of the HEW SIG-A and the one or more HEW fields following the HEW SIG-A of the HEW frame may be configured for transmission using additional data subcarriers. The additional data subcarriers may correspond to the additional reference subcarriers of the L-SIG.
1. A wireless apparatus configured to operate as a high-efficiency (HE) station, the apparatus comprising:
an interface; and
processing circuitry, coupled with the interface, and configured to:
decode a legacy long training field (L-LTF) of an HE data unit, the L-LTF comprising a legacy number of reference subcarriers;
decode a legacy signal field (L-SIG) of the HE data unit, the L-SIG comprising a legacy number of data subcarriers, and four reference subcarriers; and
decode a HE-signal field (HE-SIG-A) of the HE data unit, the HE-SIG-A comprising a total number of data subcarriers including four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG,
wherein the four reference subcarriers of the L-SIG are modulated with a known reference sequence.
2. The apparatus of claim 1 , wherein the L-LTF precedes the L-SIG, and
wherein the processing circuitry is further configured to decode the L-LTF prior to decoding the L-SIG.
3. The apparatus of claim 1 wherein the four reference subcarriers or the L-SIG comprise two subcarriers at each edge a 20 MHz channel.
4. The apparatus of claim 1 wherein the known reference sequence is stored in a memory, and wherein the processing circuitry is configured to access the memory using the interface.
5. The apparatus of claim 4 , wherein for the 20 MHz channel:
the legacy number of reference subcarriers of the L-LTF is forty-eight,
the total number of data subcarriers included in the L-SIG is forty-eight, and
the total number of data subcarriers included in the HE-SIG-A is fifty-two.
6. The apparatus of claim 5 , wherein for the 20 MHz channel:
the L-LTF includes four pilot subcarriers and the forty-eight reference subcarriers for a total of fifty-two subcarriers, the L-SIG includes four pilot subcarriers,
the forty-eight data subcarriers and the four reference subcarriers, for a total of fifty-six subcarriers, and
the HE-SIG-A further includes four pilot subcarriers and the fifty-two data subcarriers for a total of fifty-six subcarriers.
7. The apparatus of claim 5 wherein the processing circuitry is configured to:
determine a first channel estimate for subcarrier frequencies using the forty-eight reference subcarriers of the L-LTF,
determine a second channel estimate for subcarrier frequencies using the four reference subcarriers of the L-SIG; and
demodulate, using the first and second channel estimates, the fifty-two data subcarriers of the HE-SIG-A.
8. The apparatus of claim 2 , wherein in the HE data unit is a downlink HE data unit received from a master station,
wherein the processing circuitry is configured to generate an uplink HE data unit in response to receipt of the downlink HE data unit, the uplink HE data unit configured to include a L-SIG comprising the four reference subcarriers and an HE-SIG-A comprising the total number of data subcarriers including the four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG, and
wherein receipt of the downlink HE data unit is configured to trigger the processing circuitry to generate the uplink HE data unit for transmission to the master station within a transmission opportunity (TXOP) obtained by the master station.
9. The apparatus of claim 2 , wherein the HE STA is configured to operate as a master station,
wherein the HE data unit is an uplink HE data unit received in response to transmission of a downlink HE data unit by the master station, the downlink HE data unit configured to include a L-SIG comprising the four reference subcarriers and an HE-SIG-A comprising the total number of data subcarriers including the four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG,
wherein the uplink HE data unit is received within a transmission opportunity (TXOP) obtained by the master station, and
wherein transmission of the downlink HE data unit is configured to trigger transmission of the uplink HE data unit to the master station within the TXOP.
10. The apparatus of claim 1 wherein the HE data unit is received on a plurality of 20 MHz channels,
wherein the processing circuitry is further configured to:
decode the L-SIG of HE data unit, the L-SIG comprising four reference subcarriers for each 20 MHz channel, the four reference subcarriers comprising two subcarriers at each edge of each 20 MHz channel; and
decode the HE-SIG-A of the HE data unit, the HE-SIG-A comprising the total number of data subcarriers including four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG, for each 20 MHz channel.
11. The apparatus of claim 1 further comprising:
transceiver circuitry and one or more antenna coupled to the transceiver circuitry.
12. A wireless apparatus configured to operate as a high-efficiency (HE) station, the apparatus comprising:
an interface; and
processing circuitry, coupled with the interface, and configured to:
decode a legacy long training field (L-LTF) of an HE data unit, the L-LTF comprising a legacy number of reference subcarriers;
decode a legacy signal field (L-SIG) of the HE data unit, the L-SIG comprising a legacy number of data subcarriers, and four reference subcarriers; and
decode a HE-signal field (HE-SIG-A) of the HE data unit, the HE-SIG-A comprising a total number of data subcarriers including four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG,
wherein the four reference suhcarriers of the L-SIG are modulated with a known reference sequence, and
wherein the HE data unit further comprises a repetition of the L-SIG immediately following the L-SIG and prior to the HE-SIG-A.
13. A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of a wireless device configured for operation as a high-efficiency (HE) station (HE-STA), the instructions to configure the device to perform operations to:
decode a legacy long training field (L-LTF) of an HE data unit, the L-LTF comprising a legacy number of reference subcarriers;
decode a legacy signal field (L-SIG) of the HE data unit, the L-SIG comprising four reference subcarriers and a legacy number of data subcarriers; and
decode a HE-signal field (HE-SIG-A) of the HE data unit, the HE-SIG-A comprising a total number of data subcarriers including four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG,
wherein the four reference subcarriers of the L-SIG are modulated with a known reference sequence.
14. The non-transitory computer-readable storage medium of claim 13 , wherein the L-LIF precedes the L-SIG, and
wherein the processing circuitry is further configured to decode the L-LTF prior to decoding the L-SIG.
15. The non-transitory computer-readable storage medium of claim 13 , wherein the four reference subcarriers or the L-SIG comprise two subcarriers at each edge a 20 MHz channel.
16. The non-transitory computer-readable storage medium of claim 13 , wherein for the 20 MHz channel:
the legacy number of reference subcarriers of the L-LIF is forty-eight,
the total number of data subcarriers included in the L-SIG is forty-eight, and
the total number of data subcarriers included in the HE-SIG-A is fifty-two.
17. A wireless apparatus configured for operation as a high-efficiency (HE) station (HE-STA), the apparatus comprising:
memory to store a known reference sequence; and
processing circuitry to generate a HE data unit for transmission on a 20 MHz channel, the HE data unit comprising a plurality of fields,
wherein to generate the HE data unit, the processing circuitry is configured to:
encode a legacy long training field (L-LTF) of the HE data unit, the L-LTF comprising a legacy number of reference subcarriers;
encode a legacy signal field (L-SIG) of the HE data unit, the L-SIG to follow the L-LIF, the L-SIG comprising four reference subcarriers and a legacy number of data subcarriers, the four reference subcarriers of the L-SIG being modulated with the known reference sequence;
encode a HE-signal field (HE-SIG-A) of the HE data unit, the HE-SIG-A comprising a total number of data subcarriers including four data subcarriers corresponding in frequency to the four reference subcarriers of the L-SIG; and
configure a subcarrier power allocation of the subcarriers of the L-SIG and the HE-SIG-A so that the L-SIG has a same total power as the L-LTF and that the HE-SIG-A has the same total power as the L-LTF, for transmission of the L-SIG and the HE-SIG-A on the 20 MHz channel.
18. The apparatus of claim 17 wherein the processing circuitry is to configure transceiver circuitry to transmit the HE data unit, including the L-LTF, the L-SIG, and the HE-SIGA, on each of a plurality of 20 MHz channels,
wherein the L-LTF, the L-SIG, and the HE-SIG-A are each configured to be transmitted at the same total power.
19. The apparatus of claim 18 wherein the processing circuitry is configured to:
scale the subcarrier power allocation of each of the subcarriers of the L-SIG by a ratio of the legacy number of subcarriers of the L-LTF to a total number of subcarriers of the L-SIG, and
scale the subcarrier power allocation of each of the subcarriers of the HE-SIG-A by a ratio of the legacy number of subcarriers of the L-LTF to a total number of subcarriers of the HE-SIG-A.
20. The apparatus of claim 17 wherein the four reference subcarriers or the L-SIG comprise two subcarriers at an edge a 20 MHz channel.