Method and apparatus for configuring long training field in wireless local network system
Provides are a method and apparatus for configuring an LTF sequence in a wireless LAN system. More specifically, a transmission apparatus generates an LTF sequence corresponding to a first frequency band. The transmission apparatus sends an LTF sequence corresponding to the first frequency band to a reception apparatus. In this case, an LTF sequence corresponding to the second 106-RU of a second frequency band is used as a sequence located in the second 106-RU of the second frequency band in the LTF sequence corresponding to the first frequency band. The transmission apparatus may apply a phase shift of 180° to the LTF sequence corresponding to the second 106-RU of the second frequency band.
1. A method in a wireless LAN system supporting a plurality of frequency resource units (RUs) corresponding to different frequency bands, the method comprising:
generating, by a transmission apparatus, a long training field (LTF) sequence corresponding to a first frequency band; and
sending, by the transmission apparatus, an LTF sequence corresponding to the first frequency band to a reception apparatus,
wherein an LTF sequence corresponding to a second 106-RU of a second frequency band is used as a sequence located in the second 106-RU of the second frequency band in the LTF sequence corresponding to the first frequency band, and
if a bandwidth of the first frequency band is 40 MHz and a bandwidth of the second frequency band is 20 MHz, the LTF sequence corresponding to the first frequency band is defined as follow,
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,
and
the 106-RU comprises a frequency RU having 106 subcarriers.
2. The method of claim 1 , wherein the LTF sequence corresponding to the first frequency band is disposed at intervals of 2 tones from a lowest tone having a tone index of −244 to a highest tone having a tone index of +244.
3. The method of claim 1 , wherein the LTF sequence corresponding to the second 106-RU of the second frequency band is defined as follows.
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}
.
4. The method of claim 3 , wherein if a phase shift of 180° is applied to the LTF sequence corresponding to the second 106-RU of the second frequency band, the LTF sequence corresponding to the first frequency band is defined as follows.
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}
.
5. The method of claim 1 , wherein the reception apparatus has only a capability of the second frequency band.
6. The method of claim 1 , wherein the second frequency band is located in a second subband of the first frequency band.
7. The method of claim 1 , wherein in the LTF sequence corresponding to the first frequency band, a tone is not additionally nulled.
8. A transmission apparatus in a wireless LAN system, comprising:
an RF unit configured to send or receive a radio signal; and
a processor configured to control the RF unit,
wherein the processor is configured to:
generate a long training field (LTF) sequence corresponding to a first frequency band; and
send an LTF sequence corresponding to the first frequency band to a reception apparatus,
wherein an LTF sequence corresponding to a second 106-RU of a second frequency band is used as a sequence located in the second 106-RU of the second frequency band in the LTF sequence corresponding to the first frequency band, and
if a bandwidth of the first frequency band is 40 MHz and a bandwidth of the second frequency band is 20 MHz, the LTF sequence corresponding to the first frequency band is defined as follow,
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}
,
and
the 106-RU comprises a frequency RU having 106 subcarriers.
9. The transmission apparatus of claim 8 , wherein the LTF sequence corresponding to the second 106-RU of the second frequency band is defined as follows.
{
+
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,
+
1
,
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,
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,
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,
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,
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,
+
1
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-
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+
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+
1
,
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+
1
}
.
10. The transmission apparatus of claim 9 , wherein if a phase shift of 180° is applied to the LTF sequence corresponding to the second 106-RU of the second frequency band, the LTF sequence corresponding to the first frequency band is defined as follows.
{
+
1
,
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*
[
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]
,
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}
.