Patent Description:
In order to meet today's demands to deliver better Wi-Fi service and fulfill higher throughput requirements, there is a significant increase in density of APs to cover larger areas as compared to a few years ago.

While increase in density of APs is required to meet the aforementioned demands, it brings new challenges in densely populated deployments. For example, radios in multiple APs may transmit signals using the same channel of the same frequency band in the same area which may cause high co-channel interference between the radios. High co-channel interference can negatively affect the performance of the radios in the APs. <CIT> form part of the related prior art.

One goal of Radio Resource Management (RRM) Transmit Power Control algorithms is to reduce co-channel interference without impacting a radio's effective coverage radius. However, in dense deployments such as at enterprise sites, stadium venues or education institutions, even with standard radio frequency (RF) planning and site surveys, the APs tend to suffer from high co-channel interference. That is, multiple radios in multiple APs tend to transmit signals using the same channel of the same frequency band in the same area of the network. Though the problem is usually seen with <NUM> frequency band, radios using the <NUM> frequency band can also experience high co-channel interference.

In some instances, a network engineer considers only the <NUM> frequency band when determining the number and the layout of the APs to provide wireless access for a defined area. The <NUM> frequency band is usually considered as secondary to the <NUM> frequency band. Because of the lower frequency, wireless signals in the <NUM> frequency band can travel further than wireless signals in the <NUM> frequency band. Thus, coverage determinations made for the <NUM> frequency band are not directly applicable to the <NUM> frequency band. Therefore, the <NUM> frequency band is usually configured manually, e.g., a system administrator simply makes an educated guess on how many <NUM> radios are needed to provide sufficient coverage to the defined area. To prevent contention and reduce co-channel interference between radios in multiple APs in the <NUM> frequency band, a system administrator may manually power down some of the <NUM> radios.

However, the above manual method can be cumbersome, tedious, and results in coverage holes. Also, since redundant radios in APs are manually turned off, they will not be reactive to future changes of RF environments such as providing adequate client coverage and adjusting transmitting power when needed. The present disclosure provides a flexible radio assignment algorithm that can reduce co-channel interference caused by redundant radios in APs.

<FIG> illustrates a network controller controlling a plurality of APs in a network, according to one embodiment herein. In <FIG>, the network controller <NUM> controls a plurality of APs from AP1 to AP5. In one embodiment, each AP includes two radios where the first radio is a dedicated <NUM> radio that transmits signals in the <NUM> frequency band and the second radio is a XOR radio that can dynamically switch between the <NUM> and <NUM> frequency bands. That is, the second radio can transmit signals in either the <NUM> frequency band or the <NUM> frequency band. The two radios in an AP can be active simultaneously on the same frequency band or on different frequency bands. For example, the XOR radio and the dedicated <NUM> radio in an AP can simultaneously transmit signals in the <NUM> frequency band by using different channels of the <NUM> frequency band. In one embodiment, the network controller <NUM> can be an AP, e.g., a master AP that can control other APs. In another embodiment, the network controller <NUM> can be a separate computing device.

In one embodiment, the radios in AP1-AP5 have two operation modes, i.e., a local working mode and a monitor role. When operating in the local working mode, the dedicated <NUM> radio transmits signals dedicatedly in the <NUM> frequency band and the XOR radio transmits signals in either the <NUM> frequency band or the <NUM> frequency band. In the monitor role, however, the dedicated <NUM> radio and the XOR radio do not transmit signals in either the <NUM> or the <NUM> frequency bands. Also, in the monitor role, the radios consume lower power than in the local working mode. In the monitor role, the radios are passive monitors that can receive signals transmitted on the <NUM> or the <NUM> frequency bands but do not transmit signals.

The network controller <NUM> can determine whether a radio in an AP is redundant. That is, the network controller <NUM> can determine whether an AP's coverage area is already covered sufficiently (fully or almost fully) by at least one radio in a neighboring AP. For example, if AP1's XOR radio transmits signals using a channel of the <NUM> frequency band and if AP2 and AP3's XOR radios also transmit signals using the same channel of the <NUM> frequency band which cover the same area as AP1's XOR radio, then AP1's XOR radio is redundant. In this situation, AP1's redundant XOR radio may cause co-channel interference with AP2 and AP3's XOR radios using the same channel of the <NUM> frequency band.

If the network controller <NUM> determines that a radio in an AP is redundant in a frequency band, the network controller <NUM> manages the redundant radio to mitigate co-channel interference in the frequency band, e.g., the network controller <NUM> prohibits the redundant radio from transmitting signals in the frequency band. In one embodiment, the network controller <NUM> instructs AP1's XOR radio to switch to the <NUM> frequency band. That is, the network controller <NUM> switches AP1's XOR radio to transmit signals in the <NUM> frequency band, so that AP1's XOR radio does not transmit signals in the <NUM> frequency band, and thus, does not cause co-channel interference in the <NUM> frequency band. In another embodiment, the network controller <NUM> instructs AP1's XOR radio to change from local working mode to monitor role so that AP <NUM>'s XOR radio does not transmit signals in the <NUM> frequency band and does not cause co-channel interference in that band. In other embodiments, the network controller <NUM> instructs AP1's XOR radio to change from local working mode to provide wireless service assurance service or Channel Availability Check (CAC) for Zero-Touch Dynamic Frequency Selection (DFS) service or to operate as Client-Aware high availability (HA) Radio in a hot-standby mode.

<FIG> illustrates only one embodiment herein. In other embodiments, the network controller may control a different number of APs. In other embodiments, the APs may include a different number of radios. For example, the APs may include a dedicated <NUM> radio, a dedicated <NUM> radio, and a XOR radio. In other embodiments, the radios of the APs may transmit signals in frequency bands different from the <NUM> frequency band and the <NUM> frequency band, as understood by an ordinary person in the art.

<FIG> illustrates the network controller <NUM>, according to one embodiment herein. The network controller <NUM> includes a processor <NUM> and a memory <NUM>. The processor <NUM> may be any computer processor capable of performing the functions described herein. Although memory <NUM> is shown as a single entity, memory <NUM> may include one or more memory devices having blocks of memory associated with physical addresses, such as random access memory (RAM), read only memory (ROM), flash memory or other types of volatile and/or non-volatile memory.

The memory <NUM> includes a radio resource management (RRM) component <NUM>. The RRM component <NUM> provides a system level management of co-channel interference, radio resources, and other radio transmission characteristics in the network. The RRM component <NUM> includes core algorithms for controlling parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc. The RRM component <NUM> aims to utilize the radio-frequency resources and radio network infrastructure in an efficient way.

In one embodiment, the RRM component <NUM> receives inter-radio measurement data reported from the APs controlled by the network controller <NUM>. The inter-radio measurement data may include but is not limited to the channel frequency between two radios of different APs and the received signal strength indicator (RSSI) or path loss between two radios of different APs.

In one embodiment, the RRM component <NUM> performs the inter-radio measurement based on a neighbor discovery protocol (NDP). By using NDP, each radio in each AP sends a broadcast message using a channel to all other radios in all other APs using the same channel. The broadcast message may be a neighbor discovery packet with a predefined packet format. When a radio in an AP receives the neighbor discovery packet, it uses the neighbor discovery packet to obtain the inter-radio measurement data, and forwards the neighbor discovery packet and the inter-radio measurement data to the RRM component <NUM>. Based on the received neighbor discovery packet and the inter-radio measurement data, the RRM component <NUM> can understand how every radio using a channel hears every other radio using the same channel and how every AP relates to other APs in the network controlled by the network controller <NUM>.

The RRM component <NUM> includes a redundancy identification engine (RIE) <NUM>. Based on the measurement data received by the RRM component <NUM>, the RIE <NUM> can identify redundant radios in APs in a frequency band. The RIE <NUM> includes a density value calculator <NUM>, an AP constellation calculator <NUM> and a redundancy determinator <NUM>. The density value calculator <NUM> identifies potential redundant radios in APs, the AP constellation calculator <NUM> calculates relative locations of neighboring APs, and the redundancy determinator <NUM> determines whether a radio in an AP is redundant. The operation of the RIE <NUM> will be described in more detail below.

When a radio in an AP is identified as redundant by the RIE <NUM>, the RRM component <NUM> manages the redundant radio in the AP to mitigate co-channel interference in a frequency band, e.g., the RRM component <NUM> sends configuration messages to the AP either to switch the redundant radio to transmit signals in a different frequency band or change the radio into the monitor role. Thus, the redundant radio is prohibited from transmitting signals in the current frequency band, so that co-channel interference caused by the redundant radio is mitigated.

<FIG> illustrates a method <NUM> to implement a flexible radio assignment algorithm to APs, according to one embodiment herein. At block <NUM>, the density value calculator <NUM><NUM> calculates, for each of a plurality of APs, a respective density value based on neighboring APs that are in direct communication with the AP. In one embodiment, in order to calculate a respective density value indicating respective neighboring APs that are in direct communication with an AP at block <NUM>, the RRM component <NUM> uses NDP to identify the AP's neighboring APs.

<FIG> illustrates a neighborhood including multiple APs, according to one embodiment herein. In <FIG>, AP1 can directly communicate with AP2-AP5. That is, AP2-AP5 are first-hop neighbors of AP1. AP6 on the other hand can directly communicate only with AP2, AP7 and AP8, i.e., AP6 has three first-hop neighbors.

Using NDP, an AP sends a broadcast message to all other radios in the neighboring APs using the same band. In one embodiment, when a first-hop neighbor AP receives the neighbor discovery packet, the first-hop neighboring AP forwards the neighbor discovery packet with information indicating that the neighbor discovery packet is directly received from the sending AP to the RRM component <NUM>. In this way, the RRM component <NUM> can identify the sending AP's first-hop neighboring APs.

In one embodiment, after the first hop neighbors are identified for each AP controlled by the network controller <NUM>, the density value calculator <NUM> determines a density value, i.e., a Neighbor Density Metric (NDM) value, for the APs. In one embodiment, the NDM value for the i-th AP, i.e., NDM(i), is calculated as: <MAT> where N(i) are the first-hop neighbors of the i-th AP and PLi,j and PLdBi,j are the path loss between the i-th AP and the j-th AP in decimals and decibels respectively. Here the j-th AP is one of first-hop neighbors of the i-th AP.

Using the equation above, the NDM value for each AP controlled by the network node <NUM> can be calculated and stored in a Redundancy Determination Candidacy Indicator (RDCI) list. APs listed in the RDCI list are considered as candidate APs that may have redundant radios in a neighborhood. The RDCI list can be sorted, e.g., the AP with the highest NDM value is at the top of the RDCI list and so on. In one embodiment, an AP with a respective NDM value that is below a threshold NDM value is considered as not redundant and may be removed form the RDCI list. In other embodiments, other metrics can be used to calculate the density value for each AP. For example, a simple metric is to calculate the number of first-hop neighbors of an AP as the density value for the AP.

Returning to method <NUM>, at block <NUM>, the density value calculator <NUM> selects an AP from the plurality of APs based on the respective densities values. In one embodiment, the density value calculator <NUM> selects the AP with the highest NDM value, i.e., at the top of the RDCI list, as the first candidate AP for redundancy determination. The second and the following candidate APs can be selected based on the respective NDM value similarly, as understood by an ordinary person in the art.

In other embodiments, the density value calculator <NUM> selects the AP with the highest number of first-hop neighbors as the first candidate AP for redundancy determination. In other embodiments, the density value calculator <NUM> selects the AP with the highest cumulative RSSI for the first n first-hop neighbors as the first candidate AP for redundancy determination. In another embodiment, the density value calculator <NUM> selects the AP with the highest cumulative RSSI for the first n first-hop neighbors, where each of the first n first-hop neighbors has a respective RSSI above -<NUM> dBm, as the first candidate AP for redundancy determination.

At block <NUM>, the AP constellation calculator <NUM> calculates locations of the selected AP's respective neighboring APs relative to the selected AP. In one embodiment, the AP constellation calculator <NUM> calculates locations of neighboring APs relative to the selected AP, based on the inter-radio measurement data such as the RSSI or path loss between two radios in different APs, as explained above.

<FIG> illustrates a triangulation-based method to calculate locations of the selected AP's respective neighboring APs relative to the selected AP, according to one embodiment herein. In <FIG>, AP1 is the selected AP, e.g., the first candidate AP in the RDCI list. AP2-AP4 are the first-hop neighbors of AP1. First, the AP constellation calculator <NUM> determines locations of AP2 and AP3 relative to AP1. Then, the AP constellation calculator <NUM> determines the location of AP4 relative to AP1 using the relative locations of AP2 and AP3.

To calculate relative locations of AP2 and AP3 relative to AP1, the AP constellation calculator <NUM> estimates the distance between each pair of AP1-AP3. That is, the distances between AP1 and AP2, between AP1 and AP3 and between AP2 and AP3. In one embodiment, the inverse of the indoor Okumura-Hata model is used to derive estimated distances between each pair of AP1-AP3. Using this model, the AP constellation calculator <NUM> can use the RSSI and/or path loss between two radios of each pair of AP1-AP3 to derive estimated distances between each pair of AP1-AP3. As shown in <FIG>, the estimated distance between AP1 and AP2 is d<NUM>,<NUM>, the estimated distance between AP1 and AP3 is d<NUM>,<NUM>, and the estimated distance between AP2 and AP3 is d<NUM>,<NUM>. In other embodiments, other path loss models as known in the art can be used to derive the estimated distances between each pair of AP1-AP3.

After calculating the distances, without loss of generality, the selected AP - i.e., AP1 - is placed on the origin and has a coordinate of (<NUM>, <NUM>). The x-axis is defined as the axis that connects AP1 and one of its neighbors, e.g., AP2. Thus, as shown in <FIG>, AP2 has a coordinate of (d<NUM>,<NUM>, <NUM>). In this way, the relative location of AP2 is determined. AP3 is assumed to have a positive y-axis value with a coordinate (X<NUM>, Y<NUM>). The AP constellation calculator <NUM> can solve the following set of equations to determine the values of X<NUM> and Y<NUM>: <MAT> After calculating X<NUM> and Y<NUM>, the relative location of AP3 can be determined.

The AP constellation calculator <NUM> can also solve the set of equations to find the relative location of AP4 relative to AP1. For example, the distance d<NUM>,<NUM> between AP1 and AP4, the distance d<NUM>,<NUM>between AP2 and AP4, and the distance d<NUM>,<NUM> between AP3 and AP4, are first estimated using the inverse of the indoor Okumura-Hata model. Assuming AP4 has a coordinate (X<NUM>, Y<NUM>), the absolute values of X<NUM> and Y<NUM>, i.e., |X<NUM>| and |Y<NUM>|, can be calculated based on the above set of equations. The sign of X<NUM> and Y<NUM> can be determined based on the distance d<NUM>,<NUM>between AP2 and AP4 and the distance d<NUM>,<NUM> between AP3 and AP4. In this manner, the AP constellation calculator <NUM> can determine the locations of all the neighboring APs of AP1.

The triangulation-based method as shown in <FIG> is only one embodiment to calculate the relative locations of the neighboring APs to the selected AP. Other methods to calculate relative locations as known in the art, e.g., methods using 3D models, can also be used to calculate the relative locations of the neighboring APs to the selected AP. In other embodiments, path loss information from more than one frequency bands can be used in calculating the AP constellation. For example, since the APs have radios operating in both <NUM> and <NUM> bands, the path loss information of neighboring APs from both of these bands can be utilized in computing the relative locations and the AP constellations.

Returning to method <NUM>, once locations of the selected AP's respective neighboring APs relative to the selected AP are calculated, at block <NUM>, the redundancy determinator <NUM> determines that a radio in the selected AP is redundant based on the calculated locations. In one embodiment, at block <NUM>, the redundancy determinator <NUM> determines whether the selected candidate AP has a redundant radio by using a redundancy identification algorithm. Two redundancy identification algorithms are disclosed herein to determine whether the selected candidate AP has a redundant radio.

The first redundancy identification algorithm is multi-point check algorithm and is described using <FIG> and <FIG>. In this algorithm, a selected AP is considered to have a redundant radio if a set of points deterministically and/or uniformly distributed in the selected AP's coverage area are all covered by at least one of the selected AP's neighboring APs.

<FIG> illustrates a method <NUM> for performing the multi-point check algorithm, according to one embodiment herein. At block <NUM>, the redundancy determinator <NUM> selects a set of points distributed within a coverage area of the selected AP in a frequency band.

In one embodiment, at block <NUM>, the redundancy determinator <NUM> selects a set of <NUM> points. <FIG> illustrates the multi-point check algorithm using a <NUM>-point distribution (including the origin), according to one embodiment herein. As shown in <FIG>, a selected AP <NUM>, e.g., the first candidate AP in the RDCI list, is located at the origin with the coordinate (<NUM>, <NUM>) and another three neighboring APs <NUM> are located nearby. Each of the selected AP <NUM> and the neighboring APs <NUM> has two radios, as described above. A coverage circle <NUM> indicates the coverage area of the selected AP <NUM>'s XOR radio in the <NUM> frequency band. Similarly, the three neighboring APs <NUM>'s coverage circles are denoted as <NUM>, which indicate the coverage areas of the three neighboring APs <NUM>'s XOR radios in the <NUM> frequency band. The redundancy determinator <NUM> selects the origin and also selects another <NUM> points in the coverage circle <NUM>. As shown in <FIG>, the redundancy determinator <NUM> selects <NUM> points uniformly distributed on the coverage circle <NUM> and another <NUM> points uniformly distributed inside the coverage circle <NUM>. For simplicity of illustration, only two of the <NUM> points are denoted as <NUM>.

Returning to method <NUM>, once the set of points is selected, at block <NUM>, the redundancy determinator <NUM> determines coordinates of each of the set of points. In the embodiment as shown in <FIG>, the redundancy determinator <NUM> determines the coordinates of each of the <NUM> points <NUM> relative to the origin (the origin's coordinate is known as (<NUM>,<NUM>)). In one embodiment, the redundancy determinator <NUM> calculates the coordinates of each of the <NUM> points <NUM> relative to the origin based on the distances of each of the <NUM> points <NUM> relative to the origin and the uniform distribution of the <NUM> points.

At block <NUM> in <FIG>, the redundancy determinator <NUM> calculates RF distances between each neighboring AP of the selected candidate AP and each of the set of points. In the embodiment as shown in <FIG>, the redundancy determinator <NUM> calculates the distances between each neighboring AP <NUM> and each of the <NUM> points (the <NUM> points <NUM> and the origin), based on the coordinates of each neighboring AP <NUM> and the coordinates of each of the <NUM> points. In one embodiment, the AP constellation calculator <NUM> calculates the coordinates of each neighboring AP <NUM> relative to the origin using the above triangulation-based method, as described above. For each of the three neighboring APs <NUM>, the redundancy determinator <NUM> calculates the distances between the neighboring AP <NUM> and each of the <NUM> points.

Returning to method <NUM>, once distances between each neighboring AP of the selected candidate AP and each of the set of points are calculated, at block <NUM>, the redundancy determinator <NUM> compares the distance between a point and a neighboring AP with that neighboring AP's coverage radius in the frequency band. In the embodiment as shown in <FIG>, the redundancy determinator <NUM> compares the distance between a point <NUM> and a neighboring AP <NUM> with that neighboring AP <NUM>'s coverage radius in a frequency band. A neighboring AP <NUM>'s coverage radius is the radius of that neighboring AP <NUM>'s coverage circle <NUM>, denoted as <NUM>.

Based on the comparisons in block <NUM>, at block <NUM>, the redundancy determinator <NUM> determines whether all points of the set of points are inside at least one neighboring AP's coverage area in the frequency band. Referring to <FIG>, if the distance between a point <NUM> and a neighboring AP <NUM> is less than that neighboring AP <NUM>'s coverage radius <NUM> in a frequency band, the redundancy determinator <NUM> determines that the point <NUM> is inside the neighboring AP <NUM>'s coverage area in the frequency band. In this way, the redundancy determinator <NUM> determines whether all the <NUM> points are inside one or more neighboring APs <NUM>'s coverage area in the frequency band.

If the answer at block <NUM> is "yes", at block <NUM>, the redundancy determinator <NUM> determines that the selected candidate AP is redundant in the frequency band, i.e., the selected candidate AP has a redundant radio in the frequency band. In the embodiment as shown in <FIG>, all the <NUM> points <NUM> are inside at least one neighboring AP <NUM>'s coverage circle <NUM>. The selected AP <NUM>'s coverage area in the frequency band is considered as fully covered by one or more of its neighboring APs <NUM>. Thus, the radio in the selected AP <NUM> transmitting signals in the frequency band is determined as redundant in the <NUM> frequency band.

If the answer at block <NUM> is "no", at block <NUM>, the redundancy determinator <NUM> determines that the selected candidate AP is not redundant in the frequency band. In the embodiment as shown in <FIG>, if not all the <NUM> points are inside at least one neighboring AP <NUM>'s coverage circle <NUM>, the selected AP <NUM>'s coverage area in the frequency band is not considered as fully covered by one or more of its neighboring APs <NUM>. Thus, the redundancy determinator <NUM> determines that the selected AP <NUM>'s XOR radio is not redundant in the <NUM> frequency band.

After determining that the selected AP has a redundant radio, the redundancy determinator <NUM> implements the multi-point check algorithm to determine whether the next candidate AP in the RDCI list is redundant and so on. In one embodiment, when the selected AP is determined as redundant by the multi-point check algorithm, the selected AP is removed from the RDCI list.

In order to improve robustness and flexibility to the multi-point check algorithm, in one embodiment, the redundancy determinator <NUM> determines whether a certain number (not all) of points of the set of points are inside at least one neighboring AP's coverage area in the frequency band. That is, the determinator <NUM> checks all the points and can nonetheless determine that the radio in the selected AP <NUM> is redundant if a threshold number (but not all) of the set of points are inside a neighboring AP's coverage area in the frequency band. In another embodiment, a mathematical expression can be introduced to indicate how well the circle is covered, e.g., fully covered or almost fully covered. In one embodiment, the mathematical expression is defined as: (percentage of points in circle fully covered) + α × (percentage of points in circle covered with an additional margin based on their proximity to the origin), where α is a coefficient and <NUM> < α < <NUM>.

<FIG> only illustrates one embodiment of the multi-point check algorithm. In other embodiments, a different number of points may be used. In other embodiments, the multiple points may be distributed at different locations on or inside the selected AP's coverage circle. In other embodiments, the coverage circles may indicate different coverage areas, e.g., the XOR radios' coverage area in the <NUM> frequency band.

The second redundancy identification algorithm that may be performed at block <NUM> of <FIG> is coverage peak flattening algorithm that is described using <FIG>. <FIG> illustrates a method <NUM> to implement the coverage peak flattening algorithm, according to one embodiment herein. At block <NUM>, the redundancy determinator <NUM> determines the impact to the total coverage area if a selected AP, e.g., the candidate AP with the highest density value, is prohibited from transmitting signals in a frequency band. The total coverage area includes the area that is covered by at least one radio in the APs in the network.

If the total coverage area does not change, even after disabling the selected AP in the frequency band then it indicates that indicates that the selected candidate AP's coverage area in the frequency band is fully covered by at least one of its neighboring APs. On the other hand, if the selected candidate AP is prohibited from transmitting signals in a frequency band and the total coverage area is reduced, this indicates that the selected candidate AP's coverage area in the frequency band is not fully covered by at least one of its neighboring APs.

In one embodiment, in order to determine the impact to the total coverage area if a selected AP is prohibited from transmitting signals in a frequency band, the network controller can model the total coverage area and simulate the impact to the total coverage area if a selected AP is prohibited from transmitting signals in a frequency band. The redundancy determinator <NUM> determines whether the selected AP has a redundant radio in the frequency band, based on the simulation results. In another embodiment, the total coverage area can be modeled and the impact to the total coverage area can be simulated by a separate computing system. The separate computing system can transmit the simulation results of the impact to the total coverage area to the network controller <NUM> to determine whether the selected AP has a redundant radio in the frequency band.

<FIG> illustrates a visualized simulation of the coverage peak flattening algorithm, according to one embodiment herein. <FIG> shows a model of a <NUM> meter × <NUM> meter area with X, Y and Z axes. As shown in <FIG>, a location in the <NUM> meter × <NUM> meter area is denoted by its coordinates in X axis and Y axis, and number of APs that cover the location in a frequency band is denoted by its coordinate in Z axis. For example, <NUM> denotes a location at (<NUM>, <NUM>) which is covered by <NUM> APs in a frequency band, e.g., there are six radios in six APs that are transmitting signals in the <NUM> frequency band. Thus, the coordinate at <NUM> is (<NUM>, <NUM>, <NUM>). Similarly, <NUM> denotes a location at (<NUM>, <NUM>) which is covered by <NUM> APs in the frequency band. Thus, the coordinate at <NUM> is (<NUM>, <NUM>, <NUM>). Also, <NUM> denotes a location at (<NUM>, <NUM>) which is not covered by any AP in the frequency band. Thus, the coordinate at <NUM> is (<NUM>, <NUM>, <NUM>).

The simulation of coverage peak flattening algorithm starts from a selected AP that covers location <NUM> because the selected AP that covers location <NUM> has the highest density value (peak), i.e., the highest number of APs (<NUM> APs) that cover location <NUM> in a frequency band. In one embodiment, the selected AP can be the first candidate AP in the RDCI list. In the simulation, the selected AP that covers location <NUM> is prohibited from transmitting signals in the frequency band. The simulation results determine whether the total coverage area is changed.

Returning to method <NUM>, once the simulation for the selected AP is finished, at block <NUM>, the redundancy determinator <NUM> determines whether the impact to the total coverage area is acceptable. In one embodiment, if the total coverage area satisfies a threshold, the impact to the total coverage area is considered as acceptable. For example, the threshold can be a tolerance factor: τ, which indicates that the current total coverage area after prohibiting the selected candidate AP from transmitting signals in the frequency band is τ%, e.g., <NUM>%, of the original total coverage area before prohibiting the selected candidate AP from transmitting signals in the frequency band.

If the impact to the total coverage area is acceptable at block <NUM>, e.g., the current total coverage area is at least τ% of the original total coverage area, at block <NUM>, the redundancy determinator <NUM> determines that the selected candidate AP is redundant in the frequency band, i.e., the selected candidate AP has a redundant radio in the frequency band.

As shown in <FIG>, if the impact to the total coverage area is acceptable, the selected AP that covers location <NUM> is determined as redundant and removed from the simulation. That is, after one simulation, the coordinate at <NUM> is changed from (<NUM>, <NUM>, <NUM>) to (<NUM>, <NUM>, <NUM>).

At block <NUM>, the redundancy determinator <NUM> selects the next candidate AP, e.g., the candidate AP with the second highest density. Then the method <NUM> in <FIG> returns to block <NUM> to implement the coverage peak flattening algorithm for the next candidate AP and so on. Thus, coverage peak flattening algorithm can be implemented recursively.

On the other hand, if the impact to the total coverage area is not acceptable at block <NUM>, e.g., the current total coverage area is below τ% of the original total coverage area, the method <NUM> proceeds to block <NUM> where the redundancy determinator <NUM> determines that the selected AP is not redundant in the frequency band. When the coverage peak flattening algorithm is implemented until the impact to the total coverage area is not acceptable, e.g., the threshold is reached, the coverage peak flattening algorithm ends at block <NUM>.

In one embodiment, the simulation runs recursively until the impact to the total coverage area is not acceptable. In each iteration of the simulation, a selected AP that covers a location in the <NUM> meter × <NUM> meter area is prohibited from transmitting signals in a frequency band. When the coverage peak flattening algorithm is implemented multiple times until the impact to the total coverage area is not acceptable, e.g., the threshold is reached, multiple APs may be determined as redundant and are removed from the simulation. Accordingly, the coordinates at different locations may be changed when the simulation is ended.

<FIG> illustrates the simulation results of the coverage peak flattening algorithm, according to one embodiment herein. As shown in <FIG>, when the simulation is ended at block <NUM>, the coordinate at <NUM> is (<NUM>, <NUM>, <NUM>), which indicates that <NUM> APs are required to cover location <NUM> to satisfy the acceptable total coverage area, i.e., 3APs among the original <NUM> APs that cover location <NUM> are determined as redundant. Also, when the method <NUM> in <FIG> has ended, the coordinate at <NUM> is (<NUM>, <NUM>, <NUM>) which indicates that <NUM> APs are required to cover location <NUM> to satisfy the acceptable total coverage area, i.e., <NUM> APs among the original <NUM> APs that cover location <NUM> are determined as redundant. Thus, the number of APs that cover a same location in the <NUM> meter × <NUM> meter area is reduced, i.e., the density value (peak) is flattened. Using the method <NUM> in <FIG>, the redundancy determinator <NUM> can determine which APs are redundant based on the simulation results and remove the redundant APs from the RDCI list.

In United States, the <NUM> frequency band has only <NUM> non-overlapping channels while the <NUM> frequency band has <NUM> non-overlapping channels. That is, radios in the <NUM> frequency band are more likely to be redundant and cause co-channel interference. Because of this, the RIE <NUM> may have an additional bias factor for the <NUM> frequency band. That is, the RIE <NUM> inclines to determine a radio transmitting signals in the <NUM> frequency band as a redundant radio, compared to a radio transmitting signals in the <NUM> frequency band with a similar density value, e.g., a similar NDM value.

Returning to method <NUM>, once a radio in the selected AP is identified as redundant in a frequency band at block <NUM>, e.g., by using the multi-point check algorithm or the coverage peak flattening algorithm, at block <NUM>, the RRM component <NUM> manages the redundant radio in the selected AP to mitigate co-channel interference in the frequency band, e.g., the RRM component <NUM> prohibits the redundant radio in the selected AP from transmitting signals in the frequency band.

In one embodiment, in order to prohibit the redundant radio in the selected AP from transmitting signals in the frequency band, either the redundant radio is switched to transmit signals in a different frequency band or the redundant radio is changed to the monitor role. Specifically, once a radio in an AP is identified as redundant by the RIE <NUM>, the RRM component <NUM> sends configuration messages to the AP either to switch the redundant radio to transmit signals in a different frequency band or change the radio into a monitor role.

If an XOR radio of an AP that is transmitting signals in the <NUM> frequency band is determined as a redundant radio, the RRM component <NUM> can either switch the XOR radio to transmit signals in the <NUM> frequency band or change the XOR radio into the monitor role depending on the users' requirements or the usages of the network. For example, the RRM component <NUM> can switch the XOR radio to transmit signals in the <NUM> frequency band to serve more users in the <NUM> frequency band, or the RRM component <NUM> can change the XOR radio into the monitor role to reduce power consumption of the AP. Because the redundant XOR radio is no longer transmitting signals in the <NUM> frequency band, the redundant XOR radio does not cause co-channel interference in the <NUM> frequency band.

In one embodiment, when users in the <NUM> frequency band are associated with a weaker RSSI or in case that an neighboring <NUM> radio does not work properly, the RRM component <NUM> can revert the XOR radio back to the <NUM> frequency band to transmit signals in the <NUM> frequency band to avoid coverage holes in the <NUM> frequency band. When the XOR radio is reverted back to the <NUM> frequency band, the XOR radio will be ignored in future redundancy identification for a time period, e.g., the next <NUM> minutes, in order to avoid pinning affect.

Similarly, if an XOR radio that is transmitting signals in the <NUM> frequency band is identified as a redundant radio, the RRM component <NUM> can either switch the XOR radio to transmit signals in the <NUM> frequency band or change the XOR radio into the monitor role depending on the users' requirements or the usages of the network. Because the redundant XOR radio is no longer transmitting signals in the <NUM> frequency band, the redundant XOR radio does not cause co-channel interference in the <NUM> frequency band.

If a dedicated <NUM> radio is transmitting signals in the <NUM> frequency band is determined as a redundant radio, the RRM component <NUM> can change the dedicated <NUM> radio into the monitor role or power down the radio.

After the RRM component <NUM> manages the radio in the selected AP to mitigate co-channel interference in the frequency band, e.g., by prohibiting the redundant radio from transmitting signals in the frequency band, at block <NUM>, the RRM component <NUM> dynamically transfers the radio to operate in a suitable operation mode, based on the users' requirements and/or the network conditions.

In one embodiment, when RIE <NUM> of the network controller <NUM> identifies set of radios as redundant, RRM <NUM> of the network controller <NUM> utilizes channel, power and client optimization algorithms to evaluate RF conditions, available channel sets and client density in order to determine how to operate the redundant radios.

<FIG> illustrates that the network controller <NUM> controls multiple redundant XOR radios in <NUM> frequency band to operate in different operation modes, according to one embodiment herein. In <FIG>, the XOR radios in AP1-AP5 are determined as redundant radios in <NUM> frequency band. RRM <NUM> of the network controller <NUM> sends different configuration messages to different redundant XOR radios to instruct the redundant XOR radios to operate in different modes. For examples, the XOR radio in AP1 is switched to transmit signals in <NUM> frequency band due to high client density in <NUM> frequency band. The XOR radio in AP2 is changed to the monitor role to perform security and network monitoring. The XOR radio in AP3 is operated as a spectrum sensor to provide wireless service assurance service. The XOR radio in AP4 is operated to provide Channel Availability Check (CAC) for Zero-Touch Dynamic Frequency Selection (DFS) service. The XOR radio in AP5 is operated as Client-Aware high availability (HA) Radio in a hot-standby mode. In other embodiments, the network controller <NUM> can control the redundant XOR radios to operate in other modes, as understood by an ordinary person in the art. Thus, the flexible radio assignment algorithm enables dynamic configurations to redundant XOR radios based on evaluations of RF conditions, available channel sets and client density in the network.

<FIG> illustrates interactions between the RIE <NUM> and core algorithms of RRM <NUM>, according to one embodiment herein. As shown in <FIG>, RIE <NUM> can communicate with Dynamic Channel assignment (DCA) algorithm <NUM> and Transmit Power Control (TPC) algorithm <NUM> of RRM <NUM> in order to ensure that all identified redundant radios are not taken into considerations for subsequent implementations of DCA/TPC algorithms. Also, client database information <NUM> is sent to RIE <NUM> to estimate required coverage capacity for a given area. Triggers from TPC algorithm <NUM> and Coverage Hole Detection and Mitigation (CHDM) algorithm <NUM> indicate whether a redundant XOR radio shall continue to operate in monitor role or <NUM> mode or should revert back to <NUM> mode when there is a potential coverage hole in the <NUM> frequency band.

In one embodiment, once the XOR radio of an AP is determined as redundant in the <NUM> frequency band, DCA algorithm <NUM> computes the best channels and channel width in the <NUM> frequency band for the two radios in the AP. Due to the close proximity between the XOR radio and the dedicated <NUM> radio, for density-optimized channelization, DCA algorithm <NUM> allocates the best channel to the dedicated <NUM> radio and the second best channel to the XOR radio.

In one embodiment, in order to expedite network convergence, the flexible radio assignment algorithm can be triggered during the first RRM aggressive cycle and the algorithm continues to aggressively optimize coverage zones for the duration of the aggressive state. During the aggressive state, the flexible radio assignment algorithm runs with a default RRM interval. Once network convergence is reached, the flexible radio assignment algorithm will be running at fixed configurable interval. In order to avoid multiple XOR radios getting transferred into <NUM> frequency band or monitor role , in one iteration of implementing the flexible radio assignment algorithm, only one XOR radio in an AP within the RDCI list can be marked as redundant.

<FIG> illustrates inputs to the RIE <NUM>, according to one embodiment herein. The first input to the RIE <NUM> includes overlap estimation <NUM> of APs in a neighborhood. Overlap estimation <NUM> includes RSSI between neighboring APs, transmit power from neighboring APs and path loss factors between neighboring APs. The second input to the RIE <NUM> includes coverage adjustment <NUM> to the network. Coverage adjustment <NUM> includes pre-alarm to potential coverage holes in the network, information of clients that are trying to access the network or have accessed the network, and coverage events such as increased network load. The third input to the RIE <NUM> includes channelization <NUM>. Channelization <NUM> includes available channel, Wi-Fi metrics to calculate density values, client load and radio isolation factor. Based on these inputs, RIE <NUM> can determine whether a radio in an AP is redundant in a frequency band.

The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

In the preceding, reference is made to embodiments presented in this disclosure. However, the scope of the present disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice contemplated embodiments. Furthermore, although embodiments disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the scope of the present disclosure. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to "the invention" shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

Aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit," "module" or "system.

The present invention is an apparatus, a method, and/or a computer program product.

Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention.

Claim 1:
A method for reducing co-channel interference in a wireless network, the method comprising, by a radio resource management (<NUM>), RRM, component:
receiving inter-radio measurement data reported by a plurality of wireless access points (AP1-AP5), wherein the inter-radio measurement data relates to observations of radio frequency, RF, signals transmitted between radios of the plurality of access points;
wherein two or more (AP1, AP2) of the plurality of wireless access points comprise a first radio operative to transmit wireless signals in a first frequency band and a second radio configurable to transmit wireless signals in either the first frequency band or a second frequency band; the method is characterized by
determining from the inter-radio measurement data whether a second radio of a first wireless access point (AP1) of the wireless access points is redundant in relation to the first frequency band; and
if the second radio of the wireless access point is determined to be redundant, selecting for the second radio of the first wireless access point an operation mode from a plurality of operation modes, wherein the operation mode is a working mode to transmit signals in the second frequency band or at least not in the first frequency band or a monitor mode; and
transmitting a configuration message to the first wireless access point to configure the second radio of the first wireless access point to operate in the selected operation mode.