Frame transmitting method and frame receiving method
A method of transmitting a frame is provided by a device in a WLAN. The device sets as additional data subcarriers some of subcarriers which are not set as data subcarriers in at least part of fields included in a frame of a legacy frame format, and allocates information to the additional data subcarriers.
1. A wireless device for receiving a first frame in a wireless network, the wireless device comprising:
a set of processors; and
a set of memory units that store instructions, which when executed by the set of processors cause the wireless device to:
process a first set of symbols of a first legacy signal field of the first frame received in the wireless network, wherein the first set of symbols include (1) a first set of subcarriers that represent signaling information associated with the first frame and (2) a second set of subcarriers that represent first channel estimation information,
wherein the signaling information of the first set of subcarriers include rate and length information associated with the first frame,
wherein the first channel estimation information of the second set of subcarriers represent a predetermined pattern and have each been set to a value of −1 or 1 to form the predetermined pattern, and
wherein the first set of subcarriers includes subcarriers with indices −26 through 26, excluding a direct current subcarrier at an index of 0 and pilot tone subcarriers at indices −21, −7, 7, and 21, and
process a second set of symbols of the first frame, which include the first set of subcarriers.
2. The wireless device of claim 1 , wherein the first frame is of a first format that includes the first set of subcarriers and the second set of subcarriers being present in the first set of symbols for the first legacy signal field,
wherein the wireless device is capable of receiving a second frame of a second format, which includes a second legacy signal field that consists of the first set of subcarriers.
3. The wireless device of claim 2 , wherein the instructions, when executed by the set of processors, further cause the wireless device to:
determine that the first frame is of the first format or the second format based on the signaling information of the first legacy signal field.
4. The wireless device of claim 1 , wherein the second set of symbols represent a data field of the first frame.
5. The wireless device of claim 1 , wherein the second set of symbols represent a legacy long training field of the first frame that includes second channel estimation information.
6. The wireless device of claim 5 , wherein the second set of symbols includes subcarriers with indices of −28, −27, 27 and 28 that are used as guard tones and a subcarrier with the index of 0 as the direct current subcarrier.
7. The wireless device of claim 5 , wherein the second set of symbols of the legacy long training field immediately precede the first set of symbols of the legacy signal field in the first frame.
8. The wireless device of claim 7 , wherein a number of symbols included in the first set of symbols is one.
9. The wireless device of claim 1 , wherein a combined duration of the first set of symbols is identical to a combined duration of the second set of symbols.
10. The wireless device of claim 1 , wherein a first half of the first set of subcarriers are located on one side of the direct current subcarrier and a second half of the first set of subcarriers are located on an opposite side of the direct current subcarrier.
11. The wireless device of claim 1 , wherein a modulation and coding scheme used for the first number of subcarriers is identical to a modulation and coding scheme used for the second number of subcarriers.
12. A wireless device for transmitting a first frame in a wireless network, the wireless device comprising:
a set of processors; and
a set of memory units that store instructions, which when executed by the set of processors cause the wireless device to:
generate a first set of symbols of a first legacy signal field of the first frame, wherein the first set of symbols include (1) a first set of subcarriers that represent signaling information associated with the first frame and (2) a second set of subcarriers that represent first channel estimation information,
wherein the signaling information of the first set of subcarriers include rate and length information associated with the first frame,
wherein the first channel estimation information of the second set of subcarriers represent a predetermined pattern and have each been set to a value of −1 or 1 to form the predetermined pattern, and
wherein the first set of subcarriers includes subcarriers with indices −26 through 26, excluding a direct current subcarrier at an index of 0 and pilot tone subcarriers at indices −21, −7, 7, and 21,
generate a second set of symbols of the first frame, which include the first set of subcarriers, and
transmit the first frame in the wireless network.
13. The wireless device of claim 12 , wherein the first frame is of a first format that includes the first set of subcarriers and the second set of subcarriers being present in the first set of symbols for the first legacy signal field,
wherein the wireless device is capable of transmitting a second frame of a second format, which includes a second legacy signal field that consists of the first set of subcarriers.
14. The wireless device of claim 13 , wherein the instructions, when executed by the set of processors, further cause the wireless device to:
set the first legacy signal field to indicate that the first frame is of the first format instead of the second format.
15. The wireless device of claim 12 , wherein the second set of symbols represent a data field of the first frame.
16. The wireless device of claim 12 , wherein the second set of symbols represent a legacy long training field of the first frame that includes second channel estimation information.
17. The wireless device of claim 16 , wherein the second set of symbols includes subcarriers with indices of −28, −27, 27 and 28 that are used as guard tones and a subcarrier with the index of 0 as the direct current subcarrier.
18. The wireless device of claim 16 , wherein the second set of symbols of the legacy long training field immediately precede the first set of symbols of the legacy signal field in the first frame.
19. The wireless device of claim 12 , wherein a combined duration of the first set of symbols is identical to a combined duration of the second set of symbols.
20. The wireless device of claim 12 , wherein a first half of the first set of subcarriers are located on one side of the direct current subcarrier and a second half of the first set of subcarriers are located on an opposite side of the direct current subcarrier.