WLAN service method and WLAN system

1. A method for providing WLAN service by an access point (AP) in a WLAN system including the AP and a plurality of stations (STAs) each of which can associate with the AP, the method comprising:

dividing frequency bandwidth of available channel into a plurality of frequency-selective subchannels;

receiving, from at least some STAs (first STAs) among the plurality of STAs, CRQ (Contention Resolution reQuest) frame including a signature of the first STAs through at least some of the subchannels, the signature identifying the first STAs;

identifying the first STAs using the received CRQ frame;

estimating uplink channel quality of the first STAs using the received CRQ frame;

allocating the subchannels for the first STAs; and

broadcasting result of the subchannel allocation using CRP (Contention Resolution rePly) frame.

2. The method of claim 1 , wherein each subchannel has a bandwidth equal to or less than minimum coherence bandwidth.

3. The method of claim 1 , wherein each subchannel has a bandwidth equal to or less than 3 MHz.

4. The method of claim 3 , wherein the number of the subchannels is 14.

5. The method of claim 1 , wherein:

the signature is a binary bit sequence of 16 bits; and

each of the STAs receives a unique signature at the time of association with the AP.

6. The method of claim 1 , wherein the AP receives synthesized signal of the signature of the first STAs trying to use the subchannels for each subchannel.

7. The method of claim 1 , wherein the signature is modulated on K (K is a natural number) subchannels selected by each of the first STAs according to likelihood of good channel quality.

8. The method of claim 7 , wherein each of the first STAs selects the subchannels using the following algorithm 1.

Algorithm 1 Multi channel backoff

for i := requested subchannel i ε C do

 if subchannel i is requested & allocated then

  Pr(i) ← Pr(i) + α

 else if subchannel i is requested & not allocated then

  Pr(i) ← Pr(i)/β

 end if

end for

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9. The method of claim 1 , wherein the AP identifies the first STAs using a Bloom filter.

10. The method of claim 9 , wherein the Bloom filter is implemented through subcarrier-level signaling in OFDM system.

11. The method of claim 1 , wherein the AP estimates the uplink channel quality by measuring energy of a unique bit, which is transmitted by one STA only, included in the received CRQ frame.

12. The method of claim 1 , wherein the broadcasting is broadcasting the CRP frame including data rate information.

13. The method of claim 1 , wherein the AP identifies the first STAs using Machine Learning (ML) algorithm.

14. The method of claim 13 , wherein an ML model used in the ML algorithm is trained when a STA joins or leaves the AP.

15. A WLAN system comprising:

an access point (AP); and

a plurality of stations (STAs) each of which can associate with the AP, wherein

a channel available in the WLAN system is divided into a plurality of frequency-selective subchannels;

at least some STAs (first STAs) among the plurality of STAs transmit a CRQ (Contention Resolution reQuest) frame including a signature of the first STAs through at least some of the subchannels, the signature identifying the first STAs; and

the AP identifies the first STAs using the received CRQ frame, estimates uplink channel quality of the first STAs using the received CRQ frame, allocates the subchannels for the first STAs, and broadcasts result of the subchannel allocation using CRP (Contention Resolution rePly) frame.

16. The WLAN system of claim 15 , wherein the first STAs transmit the CRQ frames simultaneously when the channel is idle for more than DIFS (DCF Inter-Frame Space).