Wireless local area network (WLAN) density control

This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer-readable media, for managing wireless local area network (WLAN) density. The WLAN density is managed to limit how many APs can utilize a first portion of a first frequency band in a geographical area. A limit of APs may be based on an estimated amount of interference that would be caused by the APs to an incumbent system that also uses the first portion of the frequency band. The WLAN density control may prevent the estimated amount of interference caused by APs in a geographical area from exceeding a threshold interference level based on the presence of the incumbent system. WLAN density control may involve the AP configuration of a first AP or may involve the density of client devices associated with one or more APs in the geographical area.

TECHNICAL FIELD

This disclosure relates to the field of network communication, and more particularly to managing wireless local area network (WLAN) density.

DESCRIPTION OF THE RELATED TECHNOLOGY

An access point (AP) of a wireless local area network (WLAN) can enable wireless network access for a client device. The AP may provide a wireless coverage area used by one or more client devices to access the WLAN via the AP. The wireless coverage area provided by an AP may utilize a portion of a frequency band (such as a 2.4 GHz frequency band, a 5 GHz frequency band, a 6 GHz frequency band, etc.). Within each frequency band, there may be different channels which an AP may utilize for the coverage area. Some APs are capable of selecting a frequency band and a channel within the frequency band. As more WLANs are deployed, there may be increasing quantities of APs used within the same geographical area.

New technologies are being developed which can utilize overlapping portions of a frequency band. For example, WLAN signals may occupy a frequency band that is also used by signals of an incumbent system (such as satellite, radar, terrestrial radio, or cellular signals, etc.). In some implementations, it may be desirable to prevent or mitigate interference to an incumbent system caused by a WLAN utilizing an overlapping portion of a frequency band in a same geographical area.

SUMMARY

One innovative aspect of the subject matter described in this disclosure can be implemented by a first access point (AP) of a wireless local area network (WLAN). The first AP may determine a limit of APs that can utilize at least a first portion of a first frequency band in a geographical area. The limit may be based on an estimated amount of interference that would be caused by the APs to an incumbent system. The first AP may determine a quantity of existing APs in the geographical area that are currently utilizing at least the first portion of the first frequency band. The first AP may manage a configuration of the first AP based on a comparison of the quantity of existing APs and the limit.

In some implementations, the first AP may determine that a signal associated with the incumbent system has been detected in the geographical area. The first AP may set the limit based on a determination that the signal associated with the incumbent system has been detected in the geographical area.

In some implementations, the first AP may determine a threshold interference level. The first AP may determine estimated amounts of interference that would be caused by different quantities of APs to the incumbent system. The first AP may set the limit to a maximum quantity of APs having the estimated amount of interference lower than the threshold interference level.

In some implementations, the first AP may determine the limit by maintaining a history of previous amounts of interference for different quantities of APs utilizing the first portion of the first frequency band in the geographical area. The first AP may determine the limit based on the history of previous amounts of interference for different quantities of APs.

In some implementations, the first AP may determine the limit by obtaining an indication of the limit from at least one member selected from a group consisting of a configuration parameter of the first AP, a centralized server associated with the WLAN, a root AP in the geographical area, and an incumbent system detector.

In some implementations, the first AP may collect interference measurements from one or more client devices. The first AP may determine the limit based on the interference measurements from the one or more client devices.

In some implementations, the first AP may communicate a WLAN density control message to at least a second AP. The WLAN density control message may include at least one member selected from a group consisting of the limit determined by the first AP, interference measurements regarding at least the first portion of the first frequency band, identification of existing APs in the geographical area, and current amount of interference to the incumbent system caused by one or more existing APs in the geographical area.

In some implementations, the first AP may determine a current amount of interference to the incumbent system caused by the quantity of existing APs in the geographical area. The first AP may determine that the current amount of interference exceeds a cumulative interference level. The first AP may reduce a WLAN density in the geographical area in response to a determination that the current amount of interference exceeds the cumulative interference level.

In some implementations, the first AP may determine that the quantity of existing APs may be equal to or more than the limit. The first AP may reduce a WLAN density in the geographical area in response to determining that the quantity of existing APs may be equal to or more than the limit.

In some implementations, the first AP reducing the WLAN density in the geographical area may include the first AP refraining from establishing a first AP coverage area of the first AP in the first portion of the first frequency band, configuring the first AP coverage area to utilize a second portion of the first frequency band that may be different from the first portion, performing a channel reselection to a new channel that is different from the first portion of the first frequency band and establishing the first AP coverage area using the new channel, configuring the first AP coverage area to utilize a second frequency band that may be different from the first frequency band, and reducing the quantity of existing APs that are utilizing the first portion of the first frequency band by causing a second AP to modify a second AP coverage area of the second AP, or any combination thereof.

In some implementations, the first AP may receive a request from a first client device for a connection between the first client device and the first AP. The first AP may update the estimated amount of interference to the incumbent system based on a projected additional interference that would result from granting the request. The first AP may determine whether to grant or reject the request based, at least in part, on whether the estimated amount of interference to the incumbent system exceeds a threshold interference level.

In some implementations, the first portion may include a first channel defined within the first frequency band. The limit may be determined as a maximum quantity of APs that can utilize the first channel in the geographical area without disrupting the incumbent system.

In some implementations, the incumbent system may be a satellite system or a radar system associated with an incumbent signal in at least the first portion of the first frequency band.

In some implementations, the first AP may determine that the geographical area associated with the first AP matches at least part of a the satellite coverage area for the incumbent satellite signal of a satellite. The satellite coverage area may be based, at least in part, on a current geographical position of the satellite. The first AP may determine the limit to prevent the estimated amount of interference to the incumbent signal from exceeding a threshold interference level.

In some implementation, the first AP may determine the geographical area associated with the first AP. The first AP may determine that the incumbent system has a coverage area that overlaps at least part of the geographical area associated with the first AP.

In some implementations, the geographical area may be defined in relation to a location, an apartment building, an office building, a home, a business address, or a sports venue where there first AP is located.

In some implementations, the geographical area may be defined by a distance from a central location associated with the first AP.

In some implementations, a size of the geographical area may be set based on a range associated with a first AP coverage area of the first AP.

Another innovative aspect of the subject matter described in this disclosure can be implemented as a method performed by a first AP of a WLAN. The method may include determining, by the first AP, a limit of APs that can utilize at least a first portion of a first frequency band in a geographical area based on an estimated amount of interference that would be caused by the APs to an incumbent system. The method may include determining, by the first AP, a quantity of existing APs in the geographical area that are currently utilizing at least the first portion of the first frequency band. The method may include managing, by the first AP, a configuration of the first AP based on a comparison of the quantity of existing APs and the limit.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium having stored therein instructions which, when executed by a processor, cause the processor to perform the above-recited method or the above-described features of the first AP.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. The apparatus may include a processor and memory coupled with the processor. The memory may have instructions stored therein which, when executed by the processor cause the apparatus to perform the above-recited method or the above-described features of the first AP.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a system. The system may include means for implementing the above-recited method or the above-described features of the first AP.

DETAILED DESCRIPTION

In this disclosure, a network may be referred to as a wireless local area network (WLAN) when the network includes one or more access points (APs). The WLAN may provide access to a broadband network. For example, a gateway device, such as a central access point (CAP) or router, may provide access to the broadband network via a cable, a fiber optic, a powerline, or DSL network connection. Devices in a network can establish a wireless association (also referred to as a wireless link, wireless connection, or the like) with an AP to join the WLAN. An AP may provide a wireless coverage area for devices to access the WLAN via a wireless channel (from among various wireless channels defined within a frequency band). Each AP may be associated with a different AP coverage area, and the AP coverage areas may be overlapping. Each AP may utilize one or more channels within a frequency band. A channel may refer to a portion (or frequency range) that is defined within a frequency band. The channel is used by the AP to communicate with devices that have a wireless association with the AP. Similarly, the devices utilize the channel to communicate (via a wireless association) with the AP. There may be more than one AP operating in a geographical area. For example, a WLAN may include more than one AP in a geographical area. Furthermore, there may be multiple WLANs in the geographical area. In some implementations, a geographical area may be defined in relation to a location, an apartment building, office building, home, a business address, a sports venue, or the like. In some implementations, the geographical area may be defined by a distance from a central location (such as an area encompassing a 100 foot radius from a central AP or geographical address). In some other implementations, the size of the geographical area may be set based on a communication range associated with a WLAN technology.

Signals from a first AP can cause interference to an incumbent system utilizing the same frequency band within the geographical area. For example, an incumbent satellite system may utilize a portion of a 6 GHz frequency band for satellite signals. When there are few APs (such as one AP), it may be possible to select a different channel in the frequency band to avoid overlap with the portion of the frequency band used by the incumbent satellite system. Alternatively, existing solutions may prompt an AP to vacate the portion of the frequency band used by an incumbent system. However, these approaches may be ineffective when there are multiple APs in the geographical area. For example, the other channels may become saturated, and it may not be efficient to entirely vacate portions of the frequency band.

In accordance with this disclosure, WLAN density control can be implemented to permit limited use or the use of a portion of the frequency band that is also used by an incumbent system. The WLAN density control can limit a quantity of APs that utilize the portion of the frequency band to prevent or mitigate interference caused to the incumbent system by the APs. The techniques in this disclosure may permit the use of the occupied portion of the frequency band while limiting the cumulative amount of interference caused by the APs below a threshold interference level that is acceptable to the incumbent system. For example, the threshold interference level may represent an amount of interference that is acceptable without disrupting operation of the incumbent system. In some implementations, the threshold interference level may be predetermined (such as manufacturer determined, regulated by a regulatory agency, specified in a standard specification, or the like). In some implementations, the threshold interference level (or limit) may be determined using real-time calculations, comparisons with static thresholds, historical performance, or any combination thereof.

In one aspect of this disclosure, WLAN density control may be used to coordinate the establishment and configuration of various AP coverage areas in a geographical area. The WLAN density control can limit AP utilization within a single WLAN or multiple WLANs. The WLAN density control may utilize an existing WLAN protocol or a new WLAN protocol between multiple APs to manage WLAN density in a geographical area. The WLAN density may be based on AP channel selection, the quantity of client devices, power levels, and the like. Furthermore, the WLAN density control may be responsive to the transient presence of incumbent systems utilizing the frequency band in the geographical area. For example, an incumbent system detector (such as on a rooftop or base station) may detect when signals (such as satellite transmissions) of an incumbent system are present. WLAN density control may be used to limit the interference caused by APs when the signals of the incumbent system are present.

In one aspect of this disclosure, WLAN density control also may be used to manage density of client devices associated with a particular AP. For example, an AP may implement an interference mitigation technique to manage the density of client devices are associated with the AP. For multiple APs in the same WLAN, a first AP may steer a client device to a second AP if steering the client device will reduce the cumulative amount of interference caused by the first AP, second AP, and the client device.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. Permitting an AP to utilize a portion of the frequency band occupied by an incumbent system may result in more overall capacity or efficient exploitation of a frequency band. WLAN density control can manage cumulative interference caused by multiple APs in a geographical area so that the multiple APs can coexist with the incumbent system. Interference mitigation techniques also may improve service to the client devices. A WLAN may benefit from improved stability as a result of managing WLAN density and client device associations. Furthermore, a WLAN and an incumbent system can co-exist in an area while minimizing possible service interruptions caused by the co-existence.

FIG. 1depicts a system diagram of an example WLAN having multiple APs in which other networks are present in the environment. The system diagram100shows a first AP110, a second AP120, and a third AP130. The first AP110provides a first AP coverage area115. The second AP120provides a second AP coverage area125. The third AP130provides a third AP coverage area135. As shown at overlapping space105, the coverage area115and the coverage area125may overlap. There may be other APs (not shown) that are also providing AP coverage areas (not shown) in the geographical area. The geographical area ofFIG. 1may include the AP coverage areas115,125, and135of the first AP110, the second AP120, and the third AP130.

The system diagram100also shows example incumbent systems (such as a satellite system, radar system, or the like). In one example, a satellite180may send satellite signals185in the same geographical area as the coverage area115, the coverage area125, and the coverage area135. A cellular communications tower190also may send cellular signals195. The cellular signals195may be in the same geographical area as the coverage area125and the coverage area135. There may be other types of incumbent systems (not shown), such as radar, terrestrial radio, television, or the like.

Each of the first AP110, the second AP120, and the third AP130may include a density control unit. For brevity, in this description, the density control techniques will be described with regard to a first AP. However, in some implementations, multiple APs may implement the density control techniques, and the density control techniques may be coordinated among multiple APs in a geographical area.

Using the system diagram100as an example, consider the following example density control techniques which may be implemented by the first AP110. The first AP110may determine that the incumbent system (such as the satellite180) is utilizing a first portion of a first frequency band. The first portion may overlap, at least partially, with a first channel of the first frequency band that is utilized by the first AP110and the second AP120. Without considering the incumbent system, the first AP110and the second AP120may be capable of both using the same first channel even though they both have coverage areas in the overlapping space105. However, when considering the incumbent system, the first AP110may be configured to limit the cumulative interference in the first portion of the first frequency band used by the incumbent system. The first AP110may reduce its power level for the coverage area115or may switch to another channel so that the cumulative interference will remain below a threshold interference level. Alternatively, the first AP110may coordinate with the second AP120to limit transmission power of either or both of the first AP110and the second AP120.

In another example, the first AP110may be a new AP being introduced to the geographical area. The first AP110may detect (or otherwise determine) the existence of the incumbent system. If the new AP can do so without causing the cumulative interference to exceed the threshold interference level, the first AP110may utilize the first channel even though the first channel may overlap with the first portion of the frequency band used by the incumbent system. Otherwise, the first AP110may utilize a different channel or may prevent the establishment of an AP coverage area if utilizing the first channel would cause the cumulative interference to exceed the threshold interference level.

As described inFIGS. 4 and 5, the first AP110may determine a limit of APs (coexisting in a geographical area) that can utilize a channel that overlaps with the first portion of the first frequency band used by the incumbent system. The limit can be a hardware-configured value, a dynamically determined value, a system-configured value, or the like. For example, the limit may be based on empirical results in laboratory tests or other deployments of APs. Merely as a hypothetical example, consider the limit may be a value of “5,” meaning that up to 5 APs in a geographical area may utilize a first channel that overlaps (at least partially) with a first portion of a frequency band used by a satellite signal. If the first AP110determines that there are already 5 APs utilizing the first channel, the first AP110may refrain from utilizing the first channel. If the first AP110is already utilizing the first channel, and a new AP (not shown) is introduced to the geographical area, the first AP110may prevent the new AP from utilizing the first channel if there are already 5 or more APs utilizing the first channel. In another implementation, the first AP110may attempt to switch to a different channel so to prevent the quantity of APs utilizing the first channel from remaining above the limit.

Thus, the WLAN density control may be based on cumulative interference level or may be based on a comparison of the existing quantity of APs and the limit. In some implementations of this disclosure, the first AP110may operate independently to implement WLAN density control or may coordinate with other APs. For example, the first AP110may determine the cumulative interference or the quantity of existing APs by monitoring the frequency band for signals from other APs in the geographical area. In some implementations, the first AP110may exchange WLAN density control information with a second AP to obtain and share interference measurements or information relevant to the quantity of existing APs in the geographical area.

FIG. 2depicts another system diagram of an example WLAN showing an example network topology of the example WLAN. Another aspect of density control is based on a WLAN topology and the density of client devices associated with an AP. For example, APs can be linked in a topology to extend the overall wireless coverage of the WLAN. It is possible to combine multiple APs such that each AP is in communication with at least one other AP. In some implementations, the resulting topology may be a mesh topology. Client devices may associate with an AP that provides the highest signal strength. However, when performing an interference mitigation technique, it may be better to steer a client device to another AP or to reject a connection request from a client device.FIGS. 2 and 3provide an example network topology which can be used to describe some hypothetical scenarios.

In some WLAN deployments, a root AP may be used in determining a routing tree. In some other WLAN deployments, the APs may form a mesh network without a root AP. The WLAN200includes a root AP250which is communicatively coupled to a broadband network260. The root AP250may be separate or co-located with a gateway device (not shown). A gateway device, such as a modem or router, may provide access to the broadband network260. For example, the gateway device can couple to the broadband network through a cable, a fiber optic, a powerline, or DSL network connection. The network also includes multiple APs, including a first AP110, a second AP120, and a third AP130. Client devices can establish a wireless association (also referred to as a wireless link, wireless connection, or the like) with an AP to access the broadband network via the gateway device. For example, the wireless association may be in accordance with an association protocol associated with the wireless coverage area of the AP. In some implementations (as shown inFIG. 1), the root AP250is independent and separate from the multiple APs. In some other implementations, one of the multiple APs may be collocated with the root AP250or may be part of the same apparatus.

In the network topology depicted inFIG. 2, the first AP110may have a backhaul channel211to the root AP250. The second AP120may have a backhaul channel221to the root AP250. The third AP130may have a backhaul channel231to the second AP120. As shown inFIG. 2, the third AP130obtains access to the broadband network260via the second AP120and root AP250. The backhaul channels211,221, and231may be used to access the broadband network260, but also may be used to enable communication between the first AP110, the second AP120, and the third AP130. The backhaul channels211,221, and231may be any combination of wired or wireless channels. In some implementations, the APs may support both wired and wireless communication technologies, multiple wired communication technologies, or multiple wireless communication technologies. For example, the root AP250or the APs110,120, and130can support both IEEE 802.11 and powerline communication protocols. In some other examples, the root AP250or the APs110,120, and130can support a combination of IEEE 802.11 and powerline communication protocols, a combination of IEEE 802.11 and coaxial cable (Coax) based communication protocols, a combination of long-term evolution (LTE) and IEEE 802.11 communication protocols, a combination of IEEE 802.11 and Bluetooth communication protocols, and various other suitable combinations. In some implementations, the root AP250and the APs110,120, and130can comply with other wireless specifications, such as a ZigBee® specification, or a cellular radio specification or any other technically feasible wireless protocol. The link between the root AP250and the broadband network260can be referred to as a broadband link. The broadband link can provide at least a portion of a data pathway to another network (such as a communication service provider network, the Internet, etc.). The broadband link of the root AP250can be a wireless, a wired (such as through an Ethernet or powerline connection), or a hybrid link.

InFIG. 2, one or more client devices270,272, and274may be wirelessly associated with the first AP110, the second AP120, and the third AP130, respectively. The amount of interference contributed by a particular AP may depend on the quantity of client devices utilizing the AP. For example, the first AP110may cause a higher interference to an incumbent system as a result of having more client devices than it would if it had fewer client devices. In a hypothetical example, the amount of interference for the first AP110(and the cumulative interference in the geographical area) may be reduced by moving one of the client devices270from the first AP110to the second AP120. In another hypothetical example, if the first AP110receives a request for a connection from a new client device, the first AP110may reject the request to prevent the interference for the first AP110(and the cumulative interference in the geographical area) from increasing above a threshold interference level.

FIG. 3depicts another system diagram of an example WLAN showing wireless coverage areas of the multiple APs. The system diagram300shows the root AP250, the first AP110, the second AP120, and the third AP130as described inFIG. 2. The backhaul links and communication paths for the WLAN are removed for clarity. Instead, the system diagram300shows the AP coverage areas350,310,320, and330corresponding to the root AP250, the first AP110, the second AP120, and the third AP130, respectively. The initial first AP coverage area310for the first AP110may have some overlapping spaces with neighboring APs in the geographical area. For example, arrow325shows an overlapping space of the coverage areas310and the second AP coverage area320of the second AP120. Arrow355shows an overlapping space of the coverage areas310and the root AP coverage area350of the root AP250. UsingFIG. 3as a hypothetical example, the first AP110may detect the presence of an incumbent system that utilizes a first portion of the frequency band. In some implementations, the incumbent system may be a transient system, such as a satellite that can temporarily pass near the geographical area. The first AP110may determine whether a signal of the incumbent system has been detected in the geographical area. For example, the first AP110may be integrated or communicatively coupled with an incumbent system detector that can detect the presence of the signal of the incumbent system. The first AP110may implement a WLAN density control or interference mitigation technique (or both) when the signal of the incumbent system is detected.

The first AP110may determine that the cumulative interference level at the overlapping spaces325and355are higher than a threshold interference level. For example, the first AP110may estimate the cumulative interference based on interference measurements by the first AP110, interference measurement reports received from one or more client devices, the root AP250, or the second AP120, or any combination thereof. In response to determining that the cumulative interference is above the threshold interference level, the first AP110may perform an interference mitigation technique. In the example shown inFIG. 3, the first AP110may temporarily reduce its transmitter power.FIG. 3shows an updated first coverage area312that may result from the change in transmitter power. As described further inFIGS. 7 and 10, there may be other techniques that the first AP110can perform to prevent or mitigate interference to an incumbent system.

FIG. 4depicts an example spectral density graph for a frequency band. The example spectral density graph400shows a frequency band from 5925 MHz to 7250 MHz. The frequency band may be referred to as a 6 GHz frequency band. The spectral density graph400shows a first portion485(frequency range from F1to F2) of the frequency band being used by an incumbent system to transmit incumbent system signals480. AlthoughFIG. 4shows one incumbent system, in practical deployments, there may be multiple incumbent systems (not shown) that may occupy various portions of the frequency band. For brevity and clarity, the description ofFIG. 4describes one incumbent system which is operating in the first portion485. To prevent interference with the incumbent system, the signals from WLAN devices that are within the first portion485should be kept below a threshold interference level470. In some other portions of the frequency band which are not being used by other incumbent systems, the signals from WLAN devices may be increased up to a target interference level450(such as a maximum interference level permitted by a technical standard or regulatory agency).

The spectral density graph400shows a cumulative interference460caused by the WLAN devices operating within the frequency band. Arrow465, the spectral density graph400shows that the cumulative interference460exceeds the threshold interference level470. To comply with the threshold interference level470, one or more of the APs in the geographical area should modify its configuration so that the cumulative interference460will not exceed the threshold interference level470. Arrow475shows the resulting cumulative interference after a first AP performs a technique to reduce WLAN density or to reduce interference.

The spectral density graph400also shows utilization of the frequency band by several APs. A first AP may utilize a portion of the frequency band associated with range410. A second AP may utilize a portion of the frequency band associated with range420. A third AP may utilize a portion of the frequency band associated with range430. Ranges410,420, and430may be various channels used by the APs and their associated client devices. Ranges410,420, and430are depicted as stacked for illustrative purposes. The height of each range is used to show the amount of interference that each of the APs is contributing to the cumulative interference460. Other ranges or channels (not shown) may be used by other WLAN devices (not shown) in the geographical area.

In a first hypothetical scenario, a new AP is introduced to the geographical area. The new AP may initially attempt to establish a WLAN within the first portion485. However, based on the threshold interference level470and the fact that the cumulative interference should be kept below the threshold interference level470, the new AP may refrain from establishing a new WLAN in the first portion485. For example, the new AP may scan the frequency band and determine that three APs are already utilizing ranges410,420, and430within the first portion485. If a limit of coexisting APs utilizing the first portion485has been reached, the new AP may refrain from using the first portion485. Alternatively, the new AP may detect and measure the cumulative interference460and determine that establishment of a new WLAN in the first portion485would result in the cumulative interference exceeding the threshold interference level470. To avoid the first portion485, the new AP may establish a WLAN using a range440that is not within the first portion485.

In a second hypothetical scenario, the APs may be operating in ranges410,420,430, and440. A new client device may enter the geographical area and request a connection with a first AP associated with range410. However, the first AP may determine that the addition of the new client device would result in the cumulative interference exceeding the threshold interference level470. The first AP may reject the request. In some implementations, the first AP may cause the new client device to associate with another AP, such as the AP operating in range440.

In a third hypothetical scenario, the APs may be operating in ranges410,420,430, and440. A first AP associated with range410may determine that the cumulative interference460is exceeding the threshold interference level470within the first portion485. The first AP may perform an interference mitigation technique to reduce the cumulative interference. For example, the first AP may cause one or more client devices to associate with another AP, such as the AP operating in range440.

FIG. 5depicts a flowchart of example techniques for managing WLAN density. The flowchart500begins at block510. At block510, a first AP may determine a limit of APs that can utilize at least a first portion of a first frequency band in a geographical area based, at least in part, on an estimated amount of interference that would be caused by the APs to an incumbent system. For example, the limit may be determined to prevent the estimated amount of interference that would be caused by the APs to the incumbent system from exceeding a threshold interference level. There may be many ways for the first AP to determine the limit. In some implementations, the first AP may retrieve the limit from a pre-programmed configuration parameter of the first AP. In another implementation, the first AP may receive an indication of the limit from a centralized server or root AP associated with the WLAN. In another implementation, the first AP may calculate the limit based on historical measurements of interference for different quantities of APs utilizing the first portion of the first frequency band in the geographical area. For example, the first AP may maintain a history of previous amounts of interference for different quantities of APs utilizing the first portion of the first frequency band in the geographical area. The first AP may determine the limit based on the history of previous amounts of interference for different quantities of APs. In some implementations, the limit may be a maximum limit of coexisting APs that will be permitted to utilize the first portion of the first frequency band in the geographical area.

At block520, the first AP may determine a quantity of existing APs in the geographical area that is currently utilizing at least the first portion of the first frequency band. For example, the first AP may monitor or scan the frequency band to determine the existing APs that are in the geographical area and that are operating in the frequency band. The first AP may utilize beacon messages or request and response messages within the frequency band. In some implementations, the first AP may exchange messages with other APs to coordinate WLAN density control information that can be used to determine the quantity of existing APs in the geographical area or the cumulative interference caused by the existing APs.

At block530, the first AP may manage a configuration of the first AP based on a comparison of the quantity of existing APs and the limit. For example, if the quantity of existing APs is equal to or more than the limit, the first AP may modify a power level, channel selection, or frequency band used for a first AP coverage area of the first AP. Managing the configuration of the first AP may include reducing a WLAN density in the geographical area. Example techniques to reduce the WLAN density are described with regard toFIG. 7.

FIG. 6depicts a message flow diagram of an example implementation for WLAN density control. The message flow diagram600shows a first AP610and other APs620and630. At process615, the first AP610may perform passive or active scanning of the frequency band. For example, the first AP610may measure interference caused by neighboring APs and may determine a quantity of APs operating at different portions of the frequency band. The other APs620and630may perform similar activities at process625and635, respectively. Shown at arrows643and647, the APs610,620, and630determine the presence the other APs in the geographical area based on the information obtained by the processes615,625, and635.

In some implementations, the APs may exchange WLAN density control information. For example, the APs may share interference measurements regarding at least the first portion of the first frequency band or identification of existing APs in the geographical area. Shown at arrows650, the first AP610may receive WLAN density control information from the other APs620and630. In some implementations, the WLAN density control information may be included in messages defined by a protocol for WLAN devices. For example, in some implementations, the information may be provided in beacon messages.

At process660, the first AP610may estimate a medium utilization for one or more portions of the frequency band. The first AP610also may estimate the interference levels for the one or more portions. For example, the estimated interference levels may be based on a quantity of client devices, reported received signal strength indicator (RSSI) levels, or other WLAN density control information from the other APs620and630. The first AP610also may determine the presence of an incumbent system in a first portion of the frequency band. For example, the first AP610may detect signals from the incumbent system. In another example, the first AP610may determine the presence of the incumbent system based on a database or other information for coordinating the utilization of the frequency band. In some implementations, the first AP610may determine the position of a satellite above the geographical area in which the first AP610is operating.

At process670, the first AP610may determine whether to perform an interference prevention or mitigation technique. For example, the first AP610may determine to reduce the WLAN density at the first portion of the frequency band that is being used by an incumbent system. At arrow680, the first AP610may communicate with the other AP630to coordinate the interference mitigation technique. For example, the first AP610may inform the other AP630of the interference mitigation technique. In another example, the first AP610may inform the other AP630of the detected incumbent system or the estimated cumulative interference for the portion of the frequency band. At process685, the other AP630may determine whether an interference mitigation technique should be performed by the other AP630. At arrow690, the first AP610and the other AP630may coordinate the performance of interference mitigation techniques.

The processes and messages described in message flow diagram600may be iterative, shown by arrow695. For example, the first AP610may periodically or continuously perform processes660and670. In a subsequent performance of processes670, the first AP610may determine that the cumulative interference is below the threshold interference level and may not perform an interference mitigation technique if it is not needed.

FIG. 7depicts a flowchart of example techniques for reducing WLAN density. The flowchart700begins at block710. At block710, a first AP may determine to reduce WLAN density in a geographical area. In some implementations, the first AP may determine a medium utilization per channel based on metrics such as RSSI, quantity of active transmitters on the channel, proximity of other nearby APs utilizing the channel, or other metrics for quantifying WLAN density per channel. The first AP may assign a penalty value (or priority value) for each channel based on the medium utilization metrics. Upon detection of an incumbent system, the first AP begin with possible changes (such as those in blocks720-750) to the channel with the highest penalty value in an attempt to control interference to the incumbent system. In some other implementations, the first AP may utilize a pre-determined set of parameters to determine when to reduce WLAN density. For example, the pre-determined set of parameters may include a limit, such as a limit for a quantity of APs in the area, a limit regarding client connections per channel, a limit regarding transmit power, or any combination thereof. After determining to reduce WLAN density, the first AP may have several options for techniques to reduce the WLAN density. For example, the flow may continue to one or more of the blocks720,730,740, and750depicting various possible implementations which may be used individually or in various combinations. In some implementations, the selection or order of blocks720,730,740, and750may be predetermined or deterministically determined.

At block720, the first AP may refrain from establishing the first AP coverage area utilizing the first portion of the first frequency band. For example, if the first AP has not already established the first AP coverage area, the first AP may be prevented from establishing the first AP coverage area using a channel that overlaps with the first portion of the frequency band.

At block730, the first AP may configure the first AP coverage area to utilize a second portion of the first frequency band that is different from the first portion. For example, the second portion may not be used by an incumbent system or may be less saturated.

At block740, the first AP may configure the first AP coverage area to utilize a second frequency band that is different from the first frequency band. For example, the first AP may utilize a 2.4 GHz or 5 GHz frequency band if the 6 GHz frequency band is saturated by incumbent systems or other WLAN devices.

At block750, the first AP may reduce the quantity of existing APs that are utilizing the first portion of the first frequency band by causing a second AP to modify a second AP coverage area of the second AP. For example, the first AP may cause the second AP to switch to a different channel or different frequency band.

FIG. 8depicts a message flow diagram of an example implementation for managing density of client devices associated with a first AP. The message flow diagram800shows a first AP810, one other AP820, and a client device830. At process815, process825, and arrow835, the first AP810and the other AP820may perform activities similar to the corresponding process615, process625, and arrow643described inFIG. 6. As a result, the first AP810can generate or obtain the WLAN density control information.

Shown at arrow840, the first AP810may receive a request from the client device830for a new connection between the client device830and the first AP810. At process850, the first AP810may determine a projected amount of cumulative interference to an incumbent system that would result from granting the request. At process860, the first AP810may determine whether to grant or reject the request based on whether the projected amount of cumulative interference exceeds a threshold interference level. At arrow870, the first AP810may grant or deny the request.

FIG. 8also shows another example scenario which may occur after the client device830has associated with the first AP810. At process880, the first AP810may determine that the amount of cumulative interference to the incumbent system has exceeded the threshold interference level. The first AP810may determine to perform an interference mitigation technique. In the example scenario, the first AP810may determine to move the client device830from the first AP810to the other AP820. For example, causing the client device830to move to the other AP820may permit the first AP810to reduce its transmitter power. At arrow890, the first AP810may send a message to cause the client device830to move to a new connection895with the other AP820.

FIG. 9depicts a flowchart of example techniques for controlling association of a client device with a first AP. The flowchart900begins at block900. At block910, the first AP may receive a request from a first client device for a connection between the first client device and the first AP. At block920, the first AP may determine an estimated amount of interference to an incumbent system. The estimated amount of interference may be based on a projected additional interference that would result from granting the request. At block930, the first AP may determine whether to grant or reject the request based, at least in part, on whether the estimated amount of interference to the incumbent system exceeds a threshold interference level.

FIG. 10depicts a flowchart of example interference mitigation techniques. The flowchart begins at block1000. At block1010, a first AP may select an interference mitigation technique. The first AP may have several options for interference mitigation techniques. The criteria for choosing the technique (or order of techniques) may be based on how much the system needs to mitigate interference, or how fast the system should mitigate interference. In some implementations, the first AP use a pre-determined set of parameters that specify the order of interference mitigation. Using the pre-determined set of parameters may avoid the first AP having to perform complex analysis or real-time computations. In some other implementations, such as when the satellite system path is favorable for real-time interference estimation, the first AP may dynamically select a real-time mitigation technique to minimize performance and service impact to the first AP while meeting requirements for satellite system. The satellite system path may be favorable in situations when a satellite position can be predicted (or detected sooner) to be in the geographical area (or field of view) of the first AP. In such situations, the first AP may have more time available to do real-time calculations associated with the real-time mitigation techniques, such as those in blocks1020-1060. The flow may continue to one or more of the blocks1020,1030,1040,1050and1060.

At block1020, the first AP may reject a request from a first client device for a new connection between the first client device and the first AP.

At block1030, the first AP may prevent at least one existing client device from utilizing the first AP for a period of time. For example, the first AP may disable communication with the existing client device during a time period that the incumbent system is utilizing the first portion of the frequency band.

At block1040, the first AP may enable a power control feature for at least one existing client device to reduce the first amount of interference caused by the first AP coverage area.

At block1050, the first AP may cause at least one existing client device to utilize a different AP coverage area. For example, the first AP may cause the existing client device to switch to another channel utilized by the first AP or to another AP.

At block1060, the first AP may reduce the WLAN density in the geographical area. For example, the first AP may perform one or more of the techniques described inFIG. 7.

FIG. 11depicts another example system diagram describing WLAN density control based on a satellite coverage area for a satellite signal of a satellite. The system diagram1100shows the first AP110and its corresponding first AP coverage area115. A satellite1180is shown above the coverage area115. In some implementations, the satellite1180may be geostationary. In some other implementations, the satellite1180may have a non-stationary orbit around the Earth. In the example ofFIG. 11, the satellite1180is shown moving along an orbit illustrated by arrows1122and1124.

The satellite1180may be an incumbent system that is utilizing the first portion of a frequency band. The satellite1180is communicating satellite signals. A satellite coverage area1140shows the footprint of the satellites communication based on the current geographical position of the satellite. InFIG. 11, the satellite coverage area1140currently overlaps the coverage area115of the first AP110. Therefore, the first AP110may perform the WLAN density control techniques or interference mitigation techniques described herein to prevent the cumulative interference in the coverage area115from exceeding a threshold interference level. Thus, the threshold interference level may be based on a comparison of the satellite coverage area1140for the satellite signal1185and a location of first AP110. As the satellite1180moves along the orbit1124, the satellite coverage area1140may exit the coverage area115. Once the satellite coverage area1140does not overlap the coverage area115, the first AP110may change the threshold interference level to reflect the incumbent system has left. For example, the first AP110may raise the threshold interference level up to a target interference level permitted by a technical standard or jurisdictional regulation.

There may be different ways for the first AP110to detect the presence (or arrival) of the satellite1180above the location of the first AP110. In some implementations, the first AP110may determine the satellite coverage area for the satellite signal based on a current geographical position of the satellite. For example, the first AP110may obtain the current geographical position of the satellite from a satellite tracking server. The first AP110also may determine the location of the first AP. For example, the first AP110may utilize the Global Positioning System (GPS), the Global Navigation Satellite System (GLONASS), the Galileo positioning system (Galileo), the Indian Regional Navigation Satellite System (IRNSS), BeiDou Navigation Satellite System (BDS), the Quasi-Zenith Satellite System (QZSS), or the like, to determine the current geographical location of the first AP.

In some implementations, an incumbent system detector (such as a satellite tracker or signal detector) may be used to determine when a satellite is passing over the geographical area. For example, the incumbent system detector may be a rooftop appliance, a satellite receiver, antenna system, or the like, which is capable of detecting a signal from the incumbent system. The incumbent system detector may send a communication to one or more APs in the geographical area to indicate the presence of the signal from the incumbent system.

FIG. 12shows a block diagram of an example electronic device for implementing aspects of this disclosure. In some implementations, the electronic device1200may be one of an access point (including any of the APs described herein), a range extender, or other electronic systems. The electronic device1200can include a processor unit1202(possibly including multiple processors, multiple cores, multiple nodes, or implementing multi-threading, etc.). The electronic device1200also can include a memory unit1206. The memory unit1206may be system memory or any one or more of the below-described possible realizations of computer-readable media. The electronic device1200also can include a bus1210(such as PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus, AHB, AXI, etc.), and a network interface1204that can include at least one of a wireless network interface (such as a WLAN interface, a Bluetooth® interface, a WiMAX interface, a ZigBee® interface, a Wireless USB interface, etc.) and a wired network interface (such as an Ethernet interface, a powerline communication interface, etc.). In some implementations, the electronic device1200may support multiple network interfaces—each of which is configured to couple the electronic device1200to a different communication network.

The electronic device1200may include an interference estimation unit1260and a density control unit1262. In some implementations, the interference estimation unit1260and the density control unit1262can be distributed within the processor unit1202, the memory unit1206, and the bus1210. The interference estimation unit1260and the density control unit1262can perform some or all of the operations described inFIGS. 1-11above. For example, the interference estimation unit1260can determine the limit of APs that can utilize at least a first portion of a first frequency band in a geographical area based on an estimated amount of interference that would be caused by the APs. The interference estimation unit1260also may collect interference measurements from other APs or client devices and can determine a current cumulative amount of interference caused by the existing APs in the geographical area. The density control unit1262can implement the WLAN density control techniques. For example, the density control unit1262can implement techniques to reduce the WLAN density or perform the interference mitigation techniques described herein.

The memory unit1206can include computer instructions executable by the processor unit1202to implement the functionality of the implementations described inFIGS. 1-11. Any one of these functionalities may be partially (or entirely) implemented in hardware or on the processor unit1202. For example, the functionality may be implemented with an application specific integrated circuit, in logic implemented in the processor unit1202, in a co-processor on a peripheral device or card, etc. Further, realizations may include fewer or additional components not illustrated inFIG. 12(such as video cards, audio cards, additional network interfaces, peripheral devices, etc.). The processor unit1202, the memory unit1206, and the network interface1204are coupled to the bus1210. Although illustrated as being coupled to the bus1210, the memory unit1206may be coupled to the processor unit1202.

FIGS. 1-12and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently.

While the aspects of the disclosure have been described in terms of various examples with their associated operations, any number of different examples is also within the scope of the aspects of the disclosure. Alternatively, or in addition to the implementations described herein, other implementations may be possible.

For example, in some implementations, the incumbent system may be a satellite system, a radar system, a terrestrial radio system, or a cellular communications system different from the WLAN. The incumbent system also may utilize at least the first portion of the first frequency band.

In some implementations, the first AP may determine a limit of APs that can utilize at least a first portion of a first frequency band in a geographical area by retrieving the limit from a configuration parameter of the first AP.

In some implementations, the first AP may determine the limit by calculating the limit based on historical measurements of interference for different quantities of APs utilizing the first portion of the first frequency band in the geographical area.

In some implementations, the limit may be a maximum limit of coexisting APs that are permitted to utilize the first portion of the first frequency band in the geographical area.

In some implementations, the first AP may determine a current amount of interference to the incumbent system caused by the quantity of existing APs in the geographical area. The first AP may determine that the current amount of interference exceeds a threshold interference level. The first AP may perform an interference mitigation technique in response to a determination that the current amount of interference exceeds the threshold interference level.

In some implementations, the first AP performing the interference mitigation technique may include the first AP rejecting a request from a first client device for a connection between the first client device and the first AP, preventing at least one existing client device from utilizing the first AP for a period of time, enabling a power control feature for at least one existing client device to reduce a first amount of interference caused by the first AP coverage area, causing at least one existing client device to utilize a different AP coverage area, reducing the WLAN density in the geographical area, or any combination thereof.

In some implementations, the first AP managing the configuration of the first AP may include the first AP managing a density of client devices associated with the first AP coverage area compared to a second AP coverage area of a second AP.

In some implementations, the first AP may determine the satellite coverage area for the satellite signal based on a current geographical position of the satellite. The first AP may determine the location of the first AP.

In some implementations, the first AP may obtain the current geographical position of the satellite from a satellite tracking server.