Access point and methods for distinguishing HEW physical layer packets with backwards compatibility

Patent metadata

Field	Value
Publication number	US-9271241-B2
Application number	US-201414304041-A
Country	US
Kind code	B2
Filing date	Jun 13, 2014
Priority date	Nov 19, 2013
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

Embodiments of a system and methods for distinguishing high-efficiency Wi-Fi (HEW) packets from legacy packets are generally described herein. In some embodiments, an access point may select a value for the length field of a legacy signal field (L-SIG) that is non-divisible by three for communicating with HEW stations and may select a value for the length field that is divisible by three for communicating with legacy stations. In some embodiments, the access point may select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of a subsequent signal field to distinguish a high-throughput (HT) PPDU, a very-high throughput (VHT) PPDU and an HEW PPDU.

First claim

What is claimed is:

1. An access point (AP) arranged for communicating with a plurality of stations (STAs) including high-efficiency Wi-Fi (HEW) stations and legacy stations, the access point comprising hardware processing circuitry and physical layer (PHY) circuitry to:
configure a packet protocol data unit (PPDU) comprising a legacy signal field (L-SIG) following legacy training fields, the L-SIG including at least a length field and a rate field;
select a value for the length field that is not-divisible by three for communicating with the HEW stations; and
select a value for the length field that is divisible by three for communicating with at least some of the legacy stations.

2. The access point of claim 1 wherein the access point is further arranged to configure the L-SIG with a valid parity bit when the length field is selected to be divisible by three and when the length field is selected to be non-divisible by three.

3. The access point of claim 2 wherein, the access point is further arranged to configure the PPDU to include a subsequent signal field following the L-SIG, the subsequent signal field having first and second symbols that have BPSK modulation, and
wherein the access point is further arranged to select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field to distinguish a high-throughput (HT) PPDU, a very-high throughput (VHT) PPDU and an HEW PPDU.

4. The access point of claim 3 wherein for communicating with the HEW stations, the subsequent signal field is an HEW signal field (HEW-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of the first symbol of the HEW-SIG and refrain from applying a ninety-degree phase rotation to the BPSK modulation of the second symbol of the HEW-SIG.

5. The access point of claim 4 wherein for communicating with VHT stations, the subsequent signal field is an VHT signal field (VHT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of the second symbol of the VHT-SIG and refrain from applying a ninety-degree phase rotation to the BPSK modulation of the first symbol of the VHT-SIG,
wherein for communicating with HT stations, the subsequent signal field is an HT signal field (HT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of both the first symbol and the second symbol of the HT-SIG, and
wherein for communicating with non-HT stations, the access point is configured to refrain from including the subsequent signal field following the L-SIG.

6. The access point of claim 5 wherein for communicating with the HEW stations and some legacy stations including HT stations and VHT stations, the access point is arranged to select a value for the rate field to cause the non-HT stations to defer transmissions.

7. The access point of claim 1 wherein the access point is configured to multiply a ceiling function by three and subtract either two or one to calculate the value for the length field for the HEW stations, and
wherein the access point is configured to multiply the ceiling function by three and subtract three to calculate the value for the length field for non-HEW stations.

8. The access point of claim 4 wherein for communicating with HEW stations, the access point is further configured to:
configure the PPDU as an HEW PPDU to include a number of long-training fields (LTFs), the number of LTFs being based on a maximum number of streams communicated over a link;
contend for a wireless medium during a contention period to receive control of the medium for an HEW control period; and
transmit the HEW PPDU during the HEW control period, wherein during the HEW control period, the access point operates as a master station having exclusive use of the wireless medium for communication of data with a plurality of scheduled HEW stations in accordance with a non-contention based scheduled orthogonal frequency division multiple access (OFDMA) technique in accordance with signaling information indicated in the HEW-SIG,
wherein the scheduled OFDMA technique is one of an uplink OFDMA technique, a downlink OFDMA technique or a multi-user multiple-input multiple-output (MU-MIMO) technique.

9. The access point of claim 8 wherein for the HEW PPDU, each data field is associated with either a single user (SU) link or a multi-user (MU) link, each link configurable to provide multiple streams of data, and
wherein the links of the HEW PPDU are configurable to have a bandwidth of one of 20 MHz, 40 MHz, 80 MHz or 160 MHz.

10. An access point arranged for communicating with a plurality of stations including high-efficiency Wi-Fi (HEW) stations and legacy stations, the access point comprising hardware processing circuitry and physical layer (PHY) circuitry to configure a packet protocol data unit (PPDU) comprising:
a legacy signal field (L-SIG) following one or more legacy training fields; and
one or more fields following the L-SIG including a subsequent signal field, the subsequent signal field having first and second symbols that have BPSK modulation,
wherein the access point is further arranged to select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field to distinguish a high-throughput (HT) PPDU, a very-high throughput (VHT) PPDU and an HEW PPDU.

11. The access point of claim 10 wherein for communicating with the HEW stations, the subsequent signal field is an HEW signal field (HEW-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of the first symbol of the HEW-SIG and refrain from applying a ninety-degree phase rotation to the BPSK modulation of the second symbol of the HEW-SIG.

12. The access point of claim 11 wherein for communicating with VHT stations, the subsequent signal field is an VHT signal field (VHT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of the second symbol of the VHT-SIG and refrain from applying a ninety-degree phase rotation to the BPSK modulation of the first symbol of the VHT-SIG,
wherein for communicating with HT stations, the subsequent signal field is an HT signal field (HT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of both the first symbol and the second symbol of the HT-SIG, and
wherein for communicating with non-HT stations, the access point is configured to refrain from including the subsequent signal field following the L-SIG.

13. A high-efficiency Wi-Fi (HEW) station arranged to distinguish an HEW packet protocol data unit (PPDU) from a non-HEW PPDU, the HEW station comprising hardware processing circuitry and physical layer (PHY) circuitry configured to:
receive a legacy signal field (L-SIG) following legacy training fields, the L-SIG including at least a length field and a rate field;
determine whether a value for the length field is divisible by three;
verify a parity bit of the L-SIG;
identify the PPDU as an HEW PPDU when the value in the length field is not divisible three and the parity bit is verified; and
identify the PPDU as a non-HEW PPDU when the value in the length field is divisible three and the parity bit is verified.

14. The HEW station of claim 12 wherein the HEW station is further configured to:
decode subsequent fields of the PPDU when the PPDU identified as an HEW PPDU, and
refrain from decoding subsequent fields of the PPDU when the PPDU is identified as a no

Assignees

• Intel Ip Corp

Inventors

• Kenney Thomas J
• Perahia Eldad
• Azizi Shahrnaz

Classifications

• H04W52/241 Primary

  taking into account channel quality metrics, e.g. SIR, SNR, CIR or Eb/lo · CPC title

• H04W52/42

  in systems with time, space, frequency or polarisation diversity · CPC title

• H04W84/12

  WLAN [Wireless Local Area Networks] · CPC title

• H04W52/267

  taking into account the information rate · CPC title

• H04B7/0452

  Multi-user MIMO systems · CPC title