High-efficiency WLAN (HEW) master station and methods to increase information bits for HEW communication

• US 9,325,463 B2
• Filed: 07/22/2014
• Issued: 04/26/2016
• Est. Priority Date: 11/19/2013
• Status: Active Grant

• Current Assignee: Ax Wireless LLC (SY Ventures)
• Original Assignee: Intel IP Corporation (Intel Corporation)
• Inventors: Azizi, Shahrnaz, Perahia, Eldad, Kenney, Thomas J.
• Primary Examiner(s): Crutchfield, Christopher
• Application Number:
  US14/338,137
• Publication Number:
  US 20150139206A1
• Time in Patent Office: 644 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/2615 using hybrid frequency-time division multiple access [FDMA-TDMA]
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2603 Signal structure ensuring backward compatibility with legacy system
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
• CPC Class Codes: H04L 27/3483 using a modulation of the constellation points
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04L 5/0098 Signalling of the activation or deactivation of component carriers, subcarriers or frequency bands
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: H04W 52/244 Interferences in heterogeneous networks, e.g. among macro and femto or pico cells or other sector / system interference [OSI]
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/0473 : the resource being transmission power
• CPC Class Codes: H04W 72/20 : Control channels or signalling for resource management
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/27 : between access points
• CPC Class Codes: H04W 74/02 : Hybrid access
• CPC Class Codes: H04W 74/04 : Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/08 : Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0808 : using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 : Access point devices
• CPC Class Codes: H04W 88/10 : adapted for operation in multiple networks, e.g. multi-mode access points
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

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.

Claims

1. An access point configured to operate as a master station for high-efficiency WLAN (HEW) communications, the access point comprising hardware processing circuitry configured to:

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,

wherein the L-SIG is 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, and

wherein 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 are configured for transmission using additional data subcarriers, the additional data subcarriers corresponding to the additional reference subcarriers of the L-SIG.

2. The access point of claim 1 wherein for a 20 MHz channel, the legacy number of data subcarriers is forty-eight, the legacy number of pilot subcarriers is four, and the number of additional subcarriers modulated with a known reference sequence is four for a total of sixty-four subcarriers, including null subcarriers, and

wherein a number of data subcarriers of an HEW data field following the HEW SIG-A is fifty-two.

3. The access point of claim 2 wherein the HEW frame further includes a legacy long-training field (L-LTF) preceding the L-SIG, and

wherein the hardware processing circuitry is configured to scale a per-subcarrier power allocation the L-SIG by a factor of 56/52.

4. The access point of claim 2 wherein for a 20 MHz channel, the pilot subcarriers are located at positions −

21, −

7, 7, 21 with respect to a DC subcarrier and the additional reference subcarriers are located at positions −

28, −

27, 27, 28 with respect to the DC subcarrier.

5. The access point of claim 1 wherein the known reference sequence that is modulated on the additional reference subcarriers of the L-SIG is to be used for channel estimation by a receiving HEW station to allow the receiving HEW station to demodulate and decode the additional data subcarriers of the HEW SIG-A and the additional data subcarriers of the one or more HEW fields following the HEW SIG-A.

6. The access point of claim 5 wherein the hardware processing circuitry is configured to scale a per-subcarrier power allocation the L-SIG by a factor of B/A,

where A is the legacy number of data subcarriers plus the legacy number of pilot subcarriers, and B is the legacy number of data subcarriers plus the legacy number of pilot subcarriers plus the number of additional subcarriers.

7. The access point of claim 5 wherein one or more HEW fields following the HEW SIG-A of the HEW frame include:

an HEW data field; and

an HEW schedule field (HEW-SCH) preceding the data field that includes scheduling information for one or more HEW stations that are scheduled to communication with the access point during the data field in accordance with a scheduled orthogonal-frequency divisional multiple access (OFDMA) technique.

8. The access point of claim 5 wherein the HEW SIG-A comprises at least a first symbol (HEW SIG-A1) and a second symbol (HEW SIG-A2),

wherein information bits carried by HEW SIG-A1 are mapped on the legacy data subcarriers and pilot subcarriers of the HEW SIG-A1 are mapped on the legacy pilot subcarriers,

wherein the additional reference subcarriers of the HEW SIG-A1 are modulated with a known reference sequence,

wherein information bits carried by HEW SIG-A2 are mapped on the data subcarriers and the additional reference subcarriers, and

wherein pilot subcarriers of the HEW SIG-A2 are mapped on the legacy pilot subcarriers.

9. The access point of claim 1 wherein when the access point is operating as a master station, the access point is arranged to:

contend for a wireless medium during a contention period to receive control of the medium for the HEW control period; and

transmit the HEW frame during the HEW control period, wherein during the HEW control period, the master station has exclusive use of the wireless medium for communication with the scheduled HEW stations in accordance with a non-contention based multiple-access technique.

10. The access point of claim 9 wherein when the access point is operating as a master station, the access point is arranged to:

either;

transmit, within the HEW control period, downlink data multiplexed to each of a plurality of scheduled HEW stations, the downlink data from each scheduled station corresponding to one link and comprising one or more streams;

or

receive, within the HEW control period, uplink data multiplexed from the plurality of scheduled HEW stations, the uplink data from each scheduled station corresponding to one link and comprising one or more streams, and

include the number of LTFs in an LTF portion of an HEW preamble;

include an HEW schedule field (HEW-SCH) to follow the LTF portion; and

configure the HEW frame to include a legacy preamble to precede the HEW preamble.

11. A communication station configured for high-efficiency WLAN (HEW) communications, the station comprising hardware processing circuitry configured to:

receive an HEW frame that includes at least 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,

wherein the L-SIG uses 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, and

wherein 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 are configured for transmission using additional data subcarriers, the additional data subcarriers corresponding to the additional reference subcarriers of the L-SIG,

decode the data subcarriers of the L-SIG to determine length and rate information;

calculate channel estimates for the additional reference subcarriers of the L-SIG from the known reference sequence; and

utilize the channel estimates to decode the additional data subcarriers of the at least one symbol of HEW SIG-A and the one or more HEW fields following the HEW SIG-A.

12. The communication station of claim 11 further configured to refrain from decoding the additional reference subcarriers of the L-SIG.

13. The communication station of claim 12 wherein the communication station is configured to utilize channel estimates determined from a legacy training field to decode data subcarriers of the HEW SIG-A, the data subcarriers of the HEW SIG-A corresponding to the data subcarriers of the L-SIG.

14. The communication station of claim 13 further configured to determine whether a received frame is an HEW frame or a legacy frame based on whether a value in the length field of the L-SIG is divisible three or based on a phase rotation applied to BPSK modulation of first and second symbols of a subsequent signal field.

15. The communication station of claim 13, wherein the HEW SIG-A comprises at least a first symbol (HEW SIG-A1) and a second symbol (HEW SIG-A2),

wherein information bits carried by HEW SIG-A1 are mapped on the legacy data subcarriers, pilot subcarriers of the HEW SIG-A1 are mapped on the legacy pilot subcarriers,

wherein the additional reference subcarriers of the HEW SIG-A1 are modulated with a known reference sequence,

wherein information bits carried by HEW SIG-A2 are mapped on the data subcarriers and the additional reference subcarriers,

wherein pilot subcarriers of the HEW SIG-A2 are mapped on the legacy pilot subcarriers, and

wherein the communication station is further configured to:

utilize the additional reference subcarriers of the HEW SIG-A1 and the additional reference subcarriers of the L-SIG for channel estimation; and

decode the HEW SIG-A2 based on channel estimates obtained from an L-LTF, the L-SIG and the HEW SIG-A1.

16. A method for high-efficiency WLAN (HEW) communications comprising:

configuring 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,

wherein the L-SIG is 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, and

wherein 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 are configured for transmission using additional data subcarriers, the additional data subcarriers corresponding to the additional reference subcarriers of the L-SIG.

17. The method of claim 16 wherein for a 20 MHz channel, the legacy number of data subcarriers is forty-eight, the legacy number of pilot subcarriers is four, and the number of additional subcarriers modulated with a known reference sequence is four for a total of sixty-four subcarriers including null subcarriers,

wherein a number of data subcarriers of an HEW data field following the HEW SIG-A is fifty-two, and

wherein for a 20 MHz channel, the pilot subcarriers are located at positions −

21, −

7, 7, 21 with respect to a DC subcarrier and the additional reference subcarriers are located at positions −

28, −

27, 27, 28 with respect to the DC subcarrier.

18. The method of claim 17 wherein the known reference sequence that is modulated on the additional reference subcarriers of the L-SIG is to be used for channel estimation by a receiving HEW station to allow the receiving HEW station to demodulate and decode the additional data subcarriers of the HEW SIG-A and the additional data subcarriers of the one or more HEW fields following the HEW SIG-A.

19. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of an access point to perform operations for high-efficiency WLAN (HEW) communications, the operations to configure the access point to:

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,

wherein the L-SIG is 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, and

wherein 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 are configured for transmission using additional data subcarriers, the additional data subcarriers corresponding to the additional reference subcarriers of the L-SIG.

20. The non-transitory computer-readable storage medium of claim 19 wherein the known reference sequence that is modulated on the additional reference subcarriers of the L-SIG is to be used for channel estimation by a receiving HEW station to allow the receiving HEW station to demodulate and decode the additional data subcarriers of the HEW SIG-A and the additional data subcarriers of the one or more HEW fields following the HEW SIG-A.