Network-wide clear channel assessment threshold

• US 20080267079A1
• Filed: 04/25/2007
• Published: 10/30/2008
• Est. Priority Date: 04/25/2007
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Mhatre, Vivek, Papagiannaki, Konstantina
• Granted Patent: US 7,830,848 B2
• Time in Patent Office: Days
• US Class Current: 370/248
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

Overall network throughput may be increased in a wireless network through a common network-wide clear channel assessment (CCA) threshold. Each access point performs measurements, and determines suitable CCA thresholds and throughput estimates for each data rate. Results are reported to a central controller that determines the network-wide CCA threshold. The network-wide CCA threshold is then used by all access points and mobile stations.

Claims

1. A method comprising:

measuring beacon strength of access points within range;

measuring received power of the farthest mobile station;

determining suitable clear channel assessment thresholds for each supported data rate; and

reporting the suitable clear channel assessment thresholds to a central controller.

2. The method of claim 1 further comprising:

modeling the throughput at each supported data rate; and

reporting the throughput for each supported data rate to the central controller.

3. The method of claim 2 wherein modeling the throughput comprises:

${\mathrm{\gamma <br><br>}}_i=\frac{C_i}{m_i+1}$

where γ

_i is the throughput, i is the data rate index, C_i is the supported data rate, and m_i is smallest value such that;

$\underset{k=1}{\overset{M}{\sum <br><br>}}<br><br>P_I<br><br>\left(k\right)=\underset{k=1}{\overset{m_i}{\sum <br><br>}}<br><br>P_I<br><br>\left(k\right)+\underset{k=m_i+1}{\overset{M}{\sum <br><br>}}<br><br>P_I<br><br>\left(k\right),\mathrm{and}<br><br><br><br>\underset{k=m_i+1}{\overset{M}{\sum <br><br>}}<br><br>P_I<br><br>\left(k\right)<<br><br>{\mathrm{CCA}}_i$

where P_l (k) is the beacon strength of access point k, M is the number of access points, and CCA_i is the suitable clear channel assessment threshold for data rate i.

4. The method of claim 2 wherein determining the clear channel assessment threshold for each supported data rate comprises:

${\mathrm{CCA}}_i=\left(\frac{P_R}{{\mathrm{\beta <br><br>}}_i}-N_o\right)$

where i is the supported data rate index, P_R is the received power of the farthest mobile station, β

_i is the minimum power required to support the data rate, and N_o is the noise power.

5. The method of claim 2 further comprising:

determining at a central controller a network-wide clear channel assessment threshold from throughput and suitable clear channel assessment thresholds for each supported data rate received from a plurality of access points.

6. The method of claim 5 further comprising reporting the network-wide clear channel assessment threshold to the plurality of access points.

7. The method of claim 1 further comprising receiving a network-wide clear channel assessment threshold from the central controller.

8. A central controller in a wireless network to receive suitable clear channel assessment thresholds and throughput estimates for each supported data rate from a plurality of access points, and to determine a network-wide clear channel assessment threshold.

9. The central controller of claim 8 wherein the central controller maximizes the value of network throughput

$\mathrm{NetworkThroughput}=\sum _{}^{}$

1 M 

γ

i 

( l ) ( l )

where i(l) represents the highest supportable data rate for AP l with the network-wide clear channel assessment threshold, and γ

_i(l)^(l) represents the throughput of AP l using the network-wide clear channel threshold, and M represents the number of access points.

10. The central controller of claim 8 wherein the central controller comprises an access point.

11. The central controller of claim 8 comprising a wireless network connection over which to receive the suitable clear channel assessment thresholds and throughput estimates for each supported data rate from the plurality of access points.

12. The central controller of claim 8 comprising a wired network connection over which to receive the suitable clear channel assessment thresholds and throughput estimates for each supported data rate from the plurality of access points.