# US 9,001,908 B2 · Orthogonal frequency division multiplexing (OFDM) symbol formats for a wireless local area network (WLAN)

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- Number: US 9,001,908 B2
- Document ID: US9001908B2
- Status: Granted
- Kind: B2
- Application number: 14/033,120
- Filed: 2013-09-20
- Published: 2014-01-23
- Granted: 2015-04-07
- Earliest claimed: 2010-07-01
- Assignees: Marvell World Trade Ltd.
- Applicants: Marvell World Trade Ltd.
- Inventors: Hongyuan Zhang; Sudhir Srinivasa
- Web page: https://patentgrep.com/patent/US9001908B2

## CPC

- H04L 27/2626: {Arrangements specific to the transmitter only}
- H04L 5/0023: {Time-frequency-space}
- H04L 5/0044: {Allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH}
- H04L 5/0046: {Determination of the number of bits transmitted on different sub-channels}
- 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 27/2602: {Signal structure}
- H04L 27/2603: {Signal structure ensuring backward compatibility with legacy system}
- H04L 69/22: Parsing or analysis of headers
- H04L 1/0042: {Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape (H04L1/0067 takes precedence)}
- H04L 5/0064: {Rate requirement of the data, e.g. scalable bandwidth, data priority}
- H04W 84/12: WLAN [Wireless Local Area Networks]
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

In a method of generating an orthogonal frequency division multiplexing (OFDM) symbol, a plurality of information bits is encoded to generate a plurality of coded bits. The plurality of information bits corresponds to a first bandwidth, while the OFDM symbol includes a number of data tones corresponding to a second bandwidth. The coded bits are mapped to a plurality constellation symbols. The constellation symbols are mapped to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol and to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol. A subset of data subcarriers in the first plurality of data subcarriers and in the second plurality of data subcarriers are set to one or more predetermined values. The OFDM symbol is then generated to include at least the first plurality of data subcarriers and the second plurality of data subcarriers.

## Claims

### Claim 1

A method of generating an orthogonal frequency division multiplexing (OFDM) symbol of a data unit to be transmitted via a communication channel, the method comprising:
encoding a plurality of information bits to generate a plurality of coded bits to be included in the OFDM symbol, wherein the plurality of information bits corresponds to a first bandwidth, and wherein the OFDM symbol includes a number of data tones corresponding to a second bandwidth, the second bandwidth larger than the first bandwidth;
mapping the plurality of coded bits to a plurality constellation symbols;
mapping the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol;
setting a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values;
mapping the plurality of constellation symbols to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol;
setting a subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values; and
generating the OFDM symbol to include at least the first plurality of data subcarriers and the second plurality of data subcarriers.

### Claim 2 (depends on 1)

The method of claim 1, wherein generating the OFDM symbol further comprises including, in the OFDM symbol, one or more of (i) guard tones, (ii) direct current (DC) tones and (iii) pilot tones.

### Claim 3 (depends on 1)

The method of claim 1, wherein setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises setting at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a null value; and
wherein setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises setting at least one data subcarrier in the subset of data subcarriers in the second plurality of data subcarriers to the null value.

### Claim 4 (depends on 1)

The method of claim 1, wherein setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises setting at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a non-zero value; and
wherein setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises setting at least one data subcarrier in the subset of data subcarriers in the second plurality of data subcarriers to the non-zero value.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
mapping the plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol; and
setting a subset of data subcarriers in the third plurality of data subcarriers to one or more predetermined values; and
wherein generating the OFDM symbol further comprises including the third plurality of data subcarriers in the OFDM symbol.

### Claim 6 (depends on 1)

The method of claim 1, further comprising generating a preamble of a physical layer (PHY) data unit, wherein the preamble includes the OFDM symbol.

### Claim 7 (depends on 1)

The method of claim 1, further comprising generating a data portion of a physical layer (PHY) data unit, wherein the data portion includes the OFDM symbol.

### Claim 8 (depends on 1)

The method of claim 1, further comprising (i) inserting one or more additional bits into the plurality of information bits and (ii) duplicating the plurality of information bits and the additional bits, prior to encoding the information bits, to generate a plurality of duplicated bits, wherein encoding the information bits comprises encoding the plurality of duplicated bits.

### Claim 9 (depends on 1)

The method of claim 1, wherein the first bandwidth corresponds to a bandwidth B and the second bandwidth corresponds to a bandwidth mB, wherein m is an integer.

### Claim 10

An apparatus, comprising:
a network interface configured to:
encode a plurality of information bits to generate a plurality of coded bits to be included in an OFDM symbol, wherein the plurality of information bits corresponds to a first bandwidth, and wherein the OFDM symbol includes a number of data tones corresponding to a second bandwidth, the second bandwidth larger than the first bandwidth,
map the plurality of coded bits to a plurality constellation symbols,
map the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol,
set a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values,
map the plurality of constellation symbols to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol,
set a subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values, and
generate the OFDM symbol to include at least the data subcarriers corresponding to the first potion and the data subcarriers corresponding to the second portion.

### Claim 11 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to include, in the OFDM symbol, one or more of (i) guard tones, (ii) direct current (DC) tones and (iii) pilot tones.

### Claim 12 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to
set at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a null value, and
set at least one data subcarrier in the subset of data subcarriers in the second plurality of data subcarriers to the null value.

### Claim 13 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to
set at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a non-zero value, and
set at least one data subcarrier in the subset of data subcarriers in the second plurality of data subcarriers to the non-zero value.

### Claim 14 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to:
map the plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol,
map a subset of data subcarriers in the third plurality of data subcarriers to one or more predetermined values, and
generate the OFDM symbol to further include the third plurality of data subcarriers.

### Claim 15 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to generate a preamble of a physical layer (PHY) data unit, wherein the preamble includes the OFDM symbol.

### Claim 16 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to generate a data portion of a physical layer (PHY) data unit, wherein the data portion includes the OFDM symbol.

### Claim 17 (depends on 10)

The apparatus of claim 10, wherein the network interface is further configured to:
insert one or more additional bits into the plurality of information bits; and
duplicate the plurality of information bits and the additional bits prior to encoding the information bits to generate a plurality of duplicated bits, wherein encoding the information bits comprises encoding the plurality of duplicated bits.

### Claim 18 (depends on 11)

The apparatus of claim 11, wherein the first bandwidth corresponds to a bandwidth B and the second bandwidth corresponds to a bandwidth mB, wherein m is an integer.