Wireless access point (AP) automatic channel selection and automatic power adjustment
View Patent ↗An automatic channel selection (ACS) process enables an access point to determine a best channel available, i.e., the channel with a least amount of interference, for it operation. When ACS is enabled, the access point scans frequencies for all neighboring access points and their signal strengths. Based on this data, the access point then determines which frequency is least likely to be interfered with by these other access points. The access point switches itself to this frequency and begins operation. During normal operation, the access point may periodically rescan the air space and reevaluate its current operating channel. Preferably, every neighboring access point has its own channel, and the co-channel interference levels should be low enough so that there is a maximum coverage and high throughput for the network. If these characteristics cannot be achieved, the access point may then adjust its power automatically to reduce the interference level in the network. This automatic power adjustment (APA) feature preferably operates across a set of access points, each of which has the function. In this manner, the transmitting power of the neighboring access points in the wireless network is “cooperatively” adjusted to minimize the channel interference and maximize the coverage and throughput for the network. A method of determining optimal access point locations for access points that perform the ACS and APA functions is also described.
1. A method operative within a wireless network having at least first and second access points operating in proximity to one another within a given area, comprising:
having each of the first and second access points select and switch to a given radio channel autonomously; and
having each of the first and second access points adjust its transmit power to a given value autonomously;
wherein the given value of the first access point is a signal strength below a given minimum noise threshold detectable by the second access point, and the given value of the second access point is a signal strength below a given minimum noise threshold detectable by the first access point;
wherein each of the first and second access points selects a given radio channel by calculating a cost function that represents a cumulative signal strength generated by relative radio frequency activity levels at a given frequency due to other access points and other RF sources operating within the given area, the cost function being independent of transmission medium activity.
2. The method as described in claim 1 further including the step of having at least one of the first and second access points re-adjust its transmit power periodically.
3. The method as described in claim 2 wherein the transmit power is re-adjusted to a higher transmit power.
4. The method as described in claim 2 wherein the transmit power is re-adjusted to a lower transmit power.
5. The method as described in claim 1 wherein each of the first and second access point selects a given radio channel at boot-up.
6. A method operative within a wireless network having a plurality of access points operating in proximity to one another within a given area, comprising:
having each of the plurality of access points select and switch to a given radio channel autonomously, wherein each of the plurality of access points then operates on a given radio channel uniquely; and
having each of the plurality of access points adjust its transmit power to a given value autonomously to minimize radio channel interference collectively across the plurality of access points;
wherein each of the plurality of access points selects a given radio channel by calculating a cost function that represents a cumulative signal strength generated by relative radio frequency activity levels at a given frequency due to other access points and other RF sources operating within the given area, the cost function being independent of transmission medium activity.
7. The method as described in claim 6 wherein the plurality of access points includes at least first and second access points, and wherein the first access point adjusts itself to have a signal strength below a given minimum noise threshold detectable by the second access point, and wherein the second access point adjusts itself to have a signal strength below a given minimum noise threshold detectable by the first access point.
8. A method, operative within an access point operating in proximity to one or more other access points within a given area, comprising:
(a) having the access point select a given radio channel for operation;
(b) setting a transmit power on the given radio channel to a given first value;
(c) periodically repeating step (a), wherein at each iteration of step (a), the access point tests whether interference on the given radio channel selected has a given relationship to a threshold;
(d) if the interference on the given radio channel selected has a given relationship to the threshold, adjusting the transmit power;
wherein the access point selects the given radio channel by calculating a cost function that represents a cumulative signal strength generated by relative radio frequency activity levels at a given frequency due to the one or more other access points and other RF sources operating within the given area, the cost function being independent of transmission medium activity.
9. The method as described in claim 8 wherein the transmit power is adjusted to a second value that is higher than the given first value.
10. The method as described in claim 8 wherein the transmit power is adjusted to a second value that is lower than the given first value.