Orthogonal frequency division multiplexing (OFDM) symbol formats for a wireless local area network (WLAN)

• US 9,001,908 B2
• Filed: 09/20/2013
• Issued: 04/07/2015
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Zhang, Hongyuan, Srinivasa, Sudhir
• Primary Examiner(s): ODOM, CURTIS B
• Application Number:
  US14/033,120
• Publication Number:
  US 20140023156A1
• Time in Patent Office: 564 Days
• Field of Search: 375/260, 375/267, 375/299, 370203-211
• US Class Current: 375/260
• CPC Class Codes: 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
• 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 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

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

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.

2. 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.

3. 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.

4. 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.

5. 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.

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

7. 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.

8. 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.

9. 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.

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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. 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.

18. 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.