Method for clear channel assessment optimization in a wireless local area network

• US 20050152313A1
• Filed: 09/09/2004
• Published: 07/14/2005
• Est. Priority Date: 01/08/2004
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Marinier, Paul, Roy, Vincent, Cave, Christopher, Cuffaro, Angelo
• Granted Patent: US 7,443,821 B2
• Time in Patent Office: Days
• US Class Current: 370/333
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A method for optimizing clear channel assessment (CCA) parameters in a wireless local area network having an access point (AP) and at least one station begins by receiving a trigger condition. An upper bound and a lower bound for an energy detect threshold (EDT) parameter are determined. A value of the EDT parameter is calculated and is bound by the upper bound and the lower bound. Lastly, the EDT parameter is updated. The method can be performed at each station or at the AP, with the updated CCA parameters being signaled to each station associated with the AP.

Claims

1. A method for optimizing clear channel assessment parameters in a wireless local area network having an access point (AP) and at least one station, the method comprising the steps of:

receiving a trigger condition;

determining an upper bound and a lower bound for an energy detection threshold (EDT) parameter;

calculating a value of the EDT parameter;

bounding the EDT parameter by the upper bound and the lower bound; and

updating the EDT parameter.

2. The method according to claim 1, wherein the trigger condition exists when a transmitted packet error rate exceeds a target maximum transmitted packet error rate and a minimum number of packets have been transmitted.

3. The method according to claim 1, wherein the trigger condition exists when a received packet error rate exceeds a target maximum received packet error rate and a minimum number of packets have been received.

4. The method according to claim 1, wherein the trigger condition exists when a minimum time period has passed, a minimum number of packets have been transmitted, and a minimum number of packets have been received.

5. The method according to claim 1, wherein the upper bound is determined by the formula:

EDT_MAX=P_STA−

(RNG_base+RNG_adj)

where P_STA is the transmission power of the station, RNG_base is a baseline range of the AP, and RNG_adj is a range adjustment value.

6. The method according to claim 1, wherein the lower bound is equal to the AP receiver sensitivity level.

7. The method according to claim 1, wherein the calculating step includes calculating the value of the EDT parameter by the formula:

$\mathrm{EDT}=\mathrm{EDT}+\left(\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{{\mathrm{PER}}_{\mathrm{Rx}}}{{\mathrm{PER}}_{\mathrm{Rx}}^{\mathrm{MAX}}}-\mathrm{\beta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{{\mathrm{PER}}_{\mathrm{Tx}}}{{\mathrm{PER}}_{\mathrm{Tx}}^{\mathrm{MAX}}}+\mathrm{\gamma <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\mathrm{DR}}{{\mathrm{DR}}^{\mathrm{MAX}}}\right)<br><br>\mathrm{\Delta <br><br>}$

where PER_Rx is a received packet error rate, PER_Rx^MAX is a target maximum received packet error rate, PER_Tx is a transmitted packet error rate, PER_Tx is a target maximum transmitted packet error rate, DR is a deferral rate, DR^MAX is a target maximum deferral rate, Δ

is a step size value, and α

, β

, and γ

are weighting factors.

8. The method according to claim 1, wherein the calculating step includes calculating an EDT transmission value and an EDT reception value.

9. The method according to claim 8, wherein the EDT transmission value is calculated by the formula:

${\mathrm{EDT}}_{\mathrm{Tx}}={\mathrm{EDT}}_{\mathrm{Tx}}+\left(\mathrm{\gamma <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\mathrm{DR}}{{\mathrm{DR}}^{\mathrm{MAX}}}-\mathrm{\beta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{{\mathrm{PER}}_{\mathrm{Tx}}}{{\mathrm{PER}}_{\mathrm{Tx}}^{\mathrm{MAX}}}\right)<br><br>\mathrm{\Delta <br><br>}$

where DR is a deferral rate, DR^MAX is a target maximum deferral rate, PER_Tx is a transmitted packet error rate, PER_Tx^MAX is a target maximum transmitted packet error rate, Δ

is a step size value, and γ and

β

are weighting factors.

10. The method according to claim 8, wherein the EDT reception value is equal to a baseline range of the AP.

11. The method according to claim 8, wherein the EDT reception value is calculated by the formula:

${\mathrm{EDT}}_{\mathrm{Rx}}={\mathrm{EDT}}_{\mathrm{MAX}}-\mathrm{\alpha <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{{\mathrm{PER}}_{\mathrm{Rx}}}{{\mathrm{PER}}_{\mathrm{Rx}}^{\mathrm{MAX}}}$

where EDT_MAX is a maximum EDT value, PER_Rx is a received packet error rate, PER_Rx^MAX is a target maximum received packet error rate, and a is a weighting factor.

12. The method according to claim 1, wherein the method is performed at each station.

13. The method according to claim 1, wherein the method is performed at the AP and the updated EDT parameter is signaled to each station associated to the AP.

14. The method according to claim 13, wherein the updated EDT parameter is signaled individually to each station associated to the AP.

15. The method according to claim 13, wherein the updated EDT parameter is broadcast simultaneously to all stations associated to the AP.

16. A method for optimizing clear channel assessment (CCA) parameters in a wireless local area network having an optimizing station and a requested station, the method comprising the steps of:

sending a CCA parameter request from the optimizing station to the requested station;

reading CCA parameters at the requested station;

reporting the CCA parameters from the requested station to the optimizing station; and

computing new CCA parameters at the optimizing station.

17. The method according to claim 16, further comprising the step of:

notifying the requested station of the new CCA parameters.

18. The method according to claim 16, wherein

the optimizing station is an access point;

and

the requested station is at least one station.

19. The method according to claim 16, wherein

the optimizing station is an access point;

and

the requested station is an access point.

20. The method according to claim 16, wherein

the optimizing station is a station;

and

the requested station is at least one station.

21. The method according to claim 16, wherein

the optimizing station is a station;

and

the requested station is an access point.

22. A method for optimizing clear channel assessment (CCA) parameters in a wireless local area network having an access point (AP) and at least one station, the method comprising the steps of:

calculating optimal CCA parameters for a station at the AP;

sending a CCA parameter control request from the AP to the station;

determining if the station can change to the requested CCA parameters, and changing the CCA parameters at the station if the change can be made; and

responding to the CCA parameter control request by sending a message from the station to the AP.

23. An access point for optimizing clear channel assessment (CCA) parameters in a wireless local area network having at least one station, said access point comprising:

a receiver;

an energy detector;

a channel availability determination device; and

a CCA calculation device which receives input parameters from said access point and calculates the CCA parameters.

24. A station for optimizing clear channel assessment (CCA) parameters in a wireless local area network having an access point, said station comprising:

a receiver;

an energy detector;

a channel availability determination device; and

a CCA calculation device which receives input parameters from said station and calculates the CCA parameters.

25. An integrated circuit for optimizing clear channel assessment (CCA) parameters in a wireless local area network, comprising:

a receiver;

an energy detector;

a channel availability determination device; and

a CCA calculation device which receives input parameters and calculates the CCA parameters.