Method and apparatus of transmitting PLCP header for sub 1 GHz communication

• US 8,948,284 B2
• Filed: 11/06/2012
• Issued: 02/03/2015
• Est. Priority Date: 11/07/2011
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Jong Hyun, Kim, Eun Sun, Yi, Yun Jung, Sohn, Ill Soo, Kim, Bong Hoe
• Primary Examiner(s): File, Erin
• Application Number:
  US13/670,324
• Publication Number:
  US 20130114757A1
• Time in Patent Office: 819 Days
• Field of Search: 375/260
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26132 using repetition

Abstract

Method and apparatus of transmitting PLCP header for sub 1 GHz communication is disclosed. A method of transmitting a physical layer convergence protocol (PLCP) header may comprise generating a short training field (STF) sequence over 1 orthogonal frequency division multiplexing (OFDM) symbol, transforming the STF sequence to repeated waveform patterns in time domain and transmitting the PLCP header comprising the STF sequence, wherein the STF sequence may be a sequence transformed to repeated waveform patterns in time domain by inverse discrete Fourier transform (IDFT).

Claims

1. A method of transmitting training fields for wireless local area network, the method comprising:

determining a short training field (STF) sequence and a number of at least one first orthogonal frequency division multiplexing (OFDM) symbol for the STF sequence based on a size of a channel bandwidth in a sub 1 GHz frequency band;

determining a long training field (LTF) sequence and a number of at least one second OFDM symbol for the LTF sequence based on the size of the channel bandwidth in the sub 1 GHz frequency band;

transmitting the STF sequence on the at least one first OFDM symbol; and

transmitting the LTF sequence on the at least one second OFDM symbol,

wherein the size of the channel bandwidth is 1 MHz, 2 MHz, 4 MHz, 8 MHz, 16 MHz or 8+8 MHz in the sub 1 GHz frequency band, and

wherein the at least one first OFDM symbol and the at least one second OFDM symbol are 1/10 down-clocked OFDM symbols having a duration of 40 micro-second.

2. The method of claim 1,

wherein the LTF sequence is the sequence of alternating 0 s and ±

1 s if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the LTF sequence transformed based on the inverse discrete Fourier transform (IDFT) is a waveform having a self-repeated pattern in the time domain if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the STF sequence transformed based on the IDFT is a waveform having a 5 times-repeated pattern in a time domain if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the number of the at least one first OFDM symbols is one if the size of the channel bandwidth is equal to or greater than 2 MHz, and

wherein the number of the at least one second OFDM symbol is one if the size of the channel bandwidth is equal to or greater than 2 MHz.

3. The method of claim 2,

wherein if the size of the channel bandwidth is equal to or greater than 2 MHz, the LTF sequence VHTLTF₋

28,28 is defined by {0, 1, LTF_left, 0, LTF_right, −

1, 0, 1}, where LTF_left={0, 1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, −

1, 0, 1, 0, −

1, 0, −

1, 0, 1, 0, 1} and LTF_right={1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, −

1, 0, −

1, 0, 1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, 1, 0}.

4. The method of claim 3,

wherein the STF sequence transformed based on the IDFT is a waveform having a 5 times-repeated pattern in a time domain if the size of the channel bandwidth is 1 MHz,

the number of the at least one first OFDM symbols is one if the size of the channel bandwidth is 1 MHz,

the number of the at least one second OFDM symbols is two if the size of the channel bandwidth is 1 MHz.

5. A wireless device transmitting a training field for wireless local area network, the wireless device comprising:

a radio frequency (RF) unit configured to transmit or receive a radio signal; and

a processor operatively coupled with the RF unit and configured to;

determine a short training field (STF) sequence, a number of at least one first orthogonal frequency division multiplexing (OFDM) symbol for the STF sequence based on a size of a channel bandwidth in a sub 1 GHz frequency band;

determine a long training field (LTF) sequence, a number of at least one second OFDM symbol for the LTF sequence based on the size of the channel bandwidth in the sub 1 GHz frequency band;

instruct the RF unit to transmit the STF sequence on the at least one first OFDM symbol; and

instruct the RF unit to transmit the LTF sequence on the at least one second OFDM symbol,

wherein the size of the channel bandwidth is 1 MHz, 2 MHz, 4 MHz, 8 MHz, 16 MHz or 8+8 MHz in the sub 1 GHz frequency band, and

wherein the at least one first OFDM symbol and the at least one second OFDM symbol are 1/10 down-clocked OFDM symbols having a duration of 40 micro-second.

6. The wireless device of claim 5,

wherein the LTF sequence is the sequence of alternating 0 s and ±

1 s if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the LTF sequence transformed based on the inverse discrete Fourier transform (IDFT) is a waveform having a self-repeated pattern in the time domain if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the STF sequence transformed based on the IDFT is a waveform having a 5 times-repeated pattern in a time domain if the size of the channel bandwidth is equal to or greater than 2 MHz,

wherein the number of the at least one first OFDM symbols is one if the size of the channel bandwidth is equal to or greater than 2 MHz, and

wherein the number of the at least one second OFDM symbol is one if the size of the channel bandwidth is equal to or greater than 2 MHz.

7. The wireless device of claim 6,

wherein if the size of the channel bandwidth is equal to or greater than 2 MHz, the LTF sequence VHTLTF₋

28,28 is defined by {0, 1, LTF_left, 0, LTF_right, −

1, 0, 1}, where LTF_left={0, 1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, −

1, 0, 1, 0, −

1, 0, −

1, 0, 1, 0, 1} and LTF_right={1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, −

1, 0, −

1, 0, 1, 0, −

1, 0, 1, 0, 1, 0, 1, 0, 1, 0}.

8. The wireless device of claim 7,

wherein the STF sequence transformed based on the IDFT is a waveform having a 5 times-repeated pattern in a time domain if the size of the channel bandwidth is 1 MHz,

wherein the number of the at least one first OFDM symbols is one if the size of the channel bandwidth is 1 MHz, and

wherein the number of the at least one second OFDM symbols is two if the size of the channel bandwidth is 1 MHz.