# US 12,184,568 B2 · Pilot tones in distributed resource unit (DRU) transmission

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- Number: US 12,184,568 B2
- Document ID: US12184568B2
- Status: Granted
- Kind: B2
- Application number: 18/513,461
- Filed: 2023-11-17
- Published: 2024-05-16
- Granted: 2024-12-31
- Earliest claimed: 2021-07-30
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Lin Yang; Bin Tian; Youhan Kim; Qifan Chen
- Web page: https://patentgrep.com/patent/US12184568B2

## CPC

- H04L 5/0044: {Allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH}
- H04L 5/0051: {of dedicated pilots, i.e. pilots destined for a single user or terminal}
- H04L 5/0041: {Frequency-non-contiguous}
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 27/26134: {Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain}
- H04L 27/2634: {Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

This disclosure provides methods, devices and systems for increasing the transmit power of wireless communication devices operating on power spectral density (PSD)-limited wireless channels. Some implementations more specifically relate to pilot tone designs that support distributed transmission. A transmitting device may modulate a physical layer convergence protocol (PLCP) protocol data unit (PPDU) on a number (M) of tones representing a logical RU associated with the legacy tone plan and may further map the M tones to M noncontiguous subcarrier indices associated with a wireless channel. The transmitting device may transmit the PPDU, over the wireless channel, with a number (N) of pilot tones each having a respective location relative to the M tones as mapped to the M noncontiguous subcarrier indices. In some implementations, the relative locations of the N pilot tones may be different than relative locations of a number (K) of pilot tones associated with the logical RU.

## Claims

### Claim 1

A wireless communication device comprising:
at least one processor; and
at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to:
modulate a physical layer convergence protocol (PLCP) protocol data unit (PPDU) on a number (M) of tones representing a logical resource unit (RU) that is associated with a number (K) of pilot tones each having a respective location relative to the M tones;
map the M tones to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning a wireless channel, the M tones mapped to the M noncontiguous subcarrier indices representing a distributed resource unit (dRU), wherein the dRU is associated with a 26-tone dRU-based hierarchical structure; and
transmit, over the wireless channel, the PPDU including a number (N) of pilot tones each having a respective location relative to the M tones as mapped to the M noncontiguous subcarrier indices and different than the relative locations of the K pilot tones, the relative locations of the N pilot tones being associated with N subcarrier indices of the plurality of subcarrier indices and based at least in part on the 26-tone dRU-based hierarchical structure.

### Claim 2 (depends on 1)

The wireless communication device of claim 1, wherein N is equal to K.

### Claim 3 (depends on 2)

The wireless communication device of claim 2, wherein the N pilot tones carry the same values as the K pilot tones.

### Claim 4 (depends on 3)

The wireless communication device of claim 3, wherein M-26 and the mapping of the M tones to the M noncontiguous subcarrier indices changes the relative locations of the K pilot tones, the N pilot tones representing the K pilot tones as a result of the mapping.

### Claim 5 (depends on 4)

The wireless communication device of claim 4, wherein the mapping of the M tones to the M noncontiguous subcarrier indices shifts the relative locations of the K pilot tones by −3 or +3.

### Claim 6 (depends on 1)

The wireless communication device of claim 1, wherein N is different than K.

### Claim 7 (depends on 1)

The wireless communication device of claim 1, wherein the N subcarrier indices are located symmetrically around a center frequency associated with the wireless channel.

### Claim 8 (depends on 1)

The wireless communication device of claim 1, wherein the N subcarrier indices are located asymmetrically around a center frequency associated with the wireless channel.

### Claim 9 (depends on 1)

The wireless communication device of claim 1, wherein the N subcarrier indices include N/2 equidistant subcarrier indices located above a carrier frequency associated with the wireless channel and include N/2 equidistant subcarrier indices located below the carrier frequency.

### Claim 10 (depends on 1)

The wireless communication device of claim 1, wherein at least one of the N subcarrier indices represents a pilot tone location that is unique to M-tone dRUs.

### Claim 11 (depends on 1)

The wireless communication device of claim 1, wherein each of the N subcarrier indices is located a respective distance from a starting subcarrier index of the M noncontiguous subcarrier indices based on a location of a starting subcarrier index relative to the wireless channel and a dRU index associated with the dRU.

### Claim 12 (depends on 1)

The wireless communication device of claim 1, wherein the N pilot tones are evenly distributed across the wireless channel.

### Claim 13

A method for wireless communication performed by a wireless communication device, comprising:
modulating a physical layer convergence protocol (PLCP) protocol data unit (PPDU) on a number (M) of tones representing a logical resource unit (RU) that is associated with a number (K) of pilot tones each having a respective location relative to the M tones;
mapping the M tones to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning a wireless channel, the M tones mapped to the M noncontiguous subcarrier indices representing a distributed resource unit (dRU), wherein the dRU is associated with a 26-tone dRU-based hierarchical structure; and
transmitting, over the wireless channel, the PPDU including a number (N) of pilot tones each having a respective location relative to the M tones as mapped to the M noncontiguous subcarrier indices and different than the relative locations of the K pilot tones, the relative locations of the N pilot tones being associated with N subcarrier indices of the plurality of subcarrier indices and based at least in part on the 26-tone dRU-based hierarchical structure.

### Claim 14 (depends on 13)

The method of claim 13, wherein N is equal to K.

### Claim 15 (depends on 14)

The method of claim 14, wherein the N pilot tones carry the same values as the K pilot tones.

### Claim 16 (depends on 15)

The method of claim 15, wherein M-26 and the mapping of the M tones to the M noncontiguous subcarrier indices changes the relative locations of the K pilot tones, the N pilot tones representing the K pilot tones as a result of the mapping.

### Claim 17 (depends on 16)

The method of claim 16, wherein the mapping of the M tones to the M noncontiguous subcarrier indices shifts the relative locations of the K pilot tones by −3 or +3.

### Claim 18 (depends on 13)

The method of claim 13, wherein N is different than K.

### Claim 19 (depends on 13)

The method of claim 13, wherein the N subcarrier indices are located symmetrically around a center frequency associated with the wireless channel.

### Claim 20 (depends on 13)

The method of claim 13, wherein the N subcarrier indices are located asymmetrically around a center frequency associated with the wireless channel.

### Claim 21 (depends on 13)

The method of claim 13, wherein the N subcarrier indices include N/2 equidistant subcarrier indices located above a carrier frequency associated with the wireless channel and include N/2 equidistant subcarrier indices located below the carrier frequency.

### Claim 22 (depends on 13)

The method of claim 13, wherein at least one of the N subcarrier indices represents a pilot tone location that is unique to M-tone dRUs.

### Claim 23 (depends on 13)

The method of claim 13, wherein each of the N subcarrier indices is located a respective distance from a starting subcarrier index of the M noncontiguous subcarrier indices based on a location of a starting subcarrier index relative to the wireless channel and a dRU index associated with the dRU.

### Claim 24 (depends on 13)

The method of claim 13, wherein the N pilot tones are evenly distributed across the wireless channel.