# US 2014/0153507 A1 · Systems and methods for phase rotating duplicate frames in wireless lan transmission

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- Number: US 2014/0153507 A1
- Document ID: US20140153507A1
- Status: Published application
- Kind: A1
- Application number: 14/091,052
- Filed: 2013-11-26
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: QUALCOMM Incorporated
- Applicants: Qualcomm Incorporated
- Inventors: Lin Yang; Bin Tian; Sameer Vermani
- Web page: https://patentgrep.com/patent/US20140153507A1

## CPC

- H04L 27/2621: {Reduction thereof using phase offsets between subcarriers}
- H04L 27/2602: {Signal structure}
- H04L 27/2613: {Structure of the reference signals}
- H04L 27/26025: {Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking (allocating sub-channels of the transmission path H04L5/003)}
- H04L 27/26132: {using repetition}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Methods, devices, and computer program products for optimally phase rotating duplicate frames in wireless LAN transmissions are disclosed. In one aspect, phase rotation sequences may be chosen in order to minimize a peak-to-average power ratio (PAPR) of a frame or data unit, or of a portion of a frame or data unit, where the frame contains a plurality of identical frequency segments, such as a duplicate frame. The method involves selecting a frame bandwidth, and then selecting a phase rotation sequence based upon the frame bandwidth. The method further includes generating a frame including a number of identical 1 MHz frequency segments, and rotating some of those segments relative to other segments, based on the selected phase rotation sequence. The method further includes transmitting the frame.

## Claims

### Claim 1

A wireless communication apparatus, comprising:
a processor configured to:
select a frame bandwidth of one of 2 MHz, 4 MHz, and 8 MHz;
select a phase rotation sequence based at least in part on the frame bandwidth, comprising:
if the frame bandwidth is 2 MHz, selecting a phase rotation sequence of [1 −1], or a scaled version of [1 −1];
if the frame bandwidth is 4 MHz, selecting a phase rotation sequence of [1 j −j −1], or a scaled version of [1 j −j −1];
if the frame bandwidth is 8 MHz, selecting a phase rotation sequence of [1 −1 1 1 1 1 −1 −1], or a scaled version of [1 −1 1 1 1 1 −1 −1];
generate a frame of the selected bandwidth, the frame having a plurality of identical 1 MHz frequency segments wherein at least one of the identical 1 MHz frequency segments is rotated with respect to at least one other identical 1 MHz frequency segment based upon the selected phase rotation sequence; and
a transmitter configured to transmit the frame having a plurality of identical 1 MHz frequency segments.

### Claim 2 (depends on 1)

The wireless communication apparatus of claim 1, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of the frame or a portion of the frame.

### Claim 3 (depends on 1)

The wireless communication apparatus of claim 1, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of at least one of a data portion and an LTF portion of the frame.

### Claim 4 (depends on 1)

The wireless communication apparatus of claim 1, wherein each of the identical 1 MHz frequency segments comprise a data segment of a packet.

### Claim 5 (depends on 1)

The wireless communication apparatus of claim 1, wherein each of the identical 1 MHz frequency segments are transmitted in adjacent 1 MHz channels.

### Claim 6

A method of transmitting a duplicate frame over a wireless communication network, the method comprising:
selecting a frame bandwidth of one of 2 MHz, 4 MHz, and 8 MHz;
selecting a phase rotation sequence based at least in part on the frame bandwidth, comprising:
if the frame bandwidth is 2 MHz, selecting a phase rotation sequence of [1 −1], or a scaled version of [1 −1];
if the frame bandwidth is 4 MHz, selecting a phase rotation sequence of [1 j −j −1], or a scaled version of [1 j −j −1];
if the frame bandwidth is 8 MHz, selecting a phase rotation sequence of [1 −1 1 1 1 1 −1 −1], or a scaled version of [1 −1 1 1 1 1 −1 −1];
generating a frame of the selected bandwidth, the frame having a plurality of identical 1 MHz frequency segments, wherein at least one of the identical 1 MHz frequency segments is rotated with respect to at least one other identical 1 MHz frequency segment based upon the selected phase rotation sequence; and
transmitting the frame having a plurality of identical 1 MHz frequency segments.

### Claim 7 (depends on 6)

The method of claim 6, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of the frame or a portion of the frame.

### Claim 8 (depends on 6)

The method of claim 6, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of at least one of a data portion and/or an LTF portion of the frame.

### Claim 9 (depends on 6)

The method of claim 6, wherein the each of the identical 1 MHz frequency segments comprise a data segment of a packet.

### Claim 10 (depends on 6)

The method of claim 6, wherein each of the identical 1 MHz frequency segments are transmitted in adjacent 1 MHz channels.

### Claim 11

A non-transitory, computer readable medium comprising instructions that when executed cause a processor in a device to perform a method of transmitting a duplicate frame over a wireless communication network, the method comprising:
selecting a frame bandwidth of one of 2 MHz, 4 MHz, and 8 MHz;
selecting a phase rotation sequence based at least in part on the frame bandwidth, comprising:
if the frame bandwidth is 2 MHz, selecting a phase rotation sequence of [1 −1], or a scaled version of [1 −1];
if the frame bandwidth is 4 MHz, selecting a phase rotation sequence of [1 j −j −1], or a scaled version of [1 j −j −1];
if the frame bandwidth is 8 MHz, selecting a phase rotation sequence of [1 −1 1 1 1 1 −1 −1], or a scaled version of [1 −1 1 1 1 1 −1 −1];
generating a frame of the selected bandwidth, the frame having a plurality of identical 1 MHz frequency segments, wherein at least one of the identical 1 MHz frequency segments is rotated with respect to at least one other identical 1 MHz frequency segment based upon the selected phase rotation sequence; and
transmitting the frame having a plurality of identical 1 MHz frequency segments.

### Claim 12 (depends on 11)

The non-transitory, computer readable medium of claim 11, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of the frame or a portion of the frame.

### Claim 13 (depends on 11)

The non-transitory, computer readable medium of claim 11, wherein at least one of the identical 1 MHz frequency segments is rotated for reducing a peak-to-average power ratio of at least one of a data portion and/or an LTF portion of the frame.

### Claim 14 (depends on 11)

The non-transitory, computer readable medium of claim 11, wherein each of the identical 1 MHz frequency segments comprise a data segment of a packet.

### Claim 15 (depends on 11)

The non-transitory, computer readable medium of claim 11, wherein each of the identical 1 MHz frequency segments are transmitted in adjacent 1 MHz channels.