First, it does not use the 3rd neighbor method or anything else really other than the neighbor lists from TPCv1. The primary difference is that TPCv1 is based on a received energy measurement at the neighboring AP.
TPCv2 calculates a cell boundary between two AP's based on the measured RF distance between them, and optimizes the coverage based on that calculation. Figure 3. Larger balls fill the box quicker, but leave larger amounts of open space between the balls that still could contain more balls. So - add some smaller balls, and fill in those spaces as well. This is essentially the same problem to be solved in getting maximum cellular coverage - larger balls will fill the space quicker but also leave larger open areas, so the equation seeks to optimize the size of all the balls in order to maximize the coverage provided.
By increasing and decreasing the cell size, and minding overlap the solution arranges variable size cells for optimum coverage. Figure 4. Channel mode is enabled at the command line of the RF group leader only. Channel mode is a good choice for High Density Deployments - as this will minimize co-channel interference, while Maximizing coverage and signal between 2 AP's on the same channel.
Adjacent channel interference will be addressed by DCA. Using Channel mode increases the power significantly. TPCv2 also adds a radio Utility feature. As the algorithm runs, it models different combinations of power to reach a solution.
As it does this it keeps track of the utility of a given radio. Each WLC will prioritize the Group Identifier values from its neighbors based first on this counter value and then, in the event of a counter value tie, on the MAC address.
Each WLC will select the one controller either a neighboring WLC or itself with the highest Group Identifier value, after which each controller will confer with the others to determine which single controller has the highest Group ID.
The Group Leader runs these algorithms every ten minutes but, as with the Coverage Hole Detection and Correction algorithm, changes are only made if determined necessary. With the DCA process, the leader considers a handful of AP-specific metrics that are taken into account when determining necessary channel changes. These metrics are: Load Measurement—Every AP measures the percentage of total time occupied by transmitting or receiving Noise—APs calculate noise values on every serviced channel.
Interference—APs report on the percentage of the medium taken up by interfering This AP signal strength information is the most important metric considered in the DCA calculation of channel energy. These values are then used by the Group Leader to determine if another channel schema will result in at least a bettering of the worst performing AP by 5dB SNR or more.
Weighting is given to APs on their operating channels such that channel adjustments are made locally, dampening changes to prevent the domino effect whereby a single change would trigger system-wide channel alterations. Clients can either reconnect to the same AP on its new channel , or roam to a nearby AP, which depends on client roaming behavior.
DCA adjustments will subsequently occur as needed. Therefore, the TCP goes through these stages which decide if a transmit power change is necessary: Determine if there is a third neighbor, and if that third neighbor is above the transmit power control threshold. Compare the calculation from step two with the current Tx power level and verify if it exceeds the TPC hysteresis.
When APs are power cycled, they use their previous power settings. TPC adjustments will subsequently occur as needed. See Table 4 for information on the supported AP transmit power levels. There is a third neighbor. This results in a Tx power increase. TPC-induced Tx decreases take place gradually, but Tx increases can take place right away. However, extra precaution has been taken in how Tx power is increased with Coverage Hole algorithm, going up, one level at a time. Coverage Hole Detection and Correction Algorithm The Coverage Hole Detection and Correction algorithm is aimed at first determining coverage holes based on the quality of client signal levels and then increasing the transmit power of the APs to which those clients are connected.
Because this algorithm is concerned with client statistics, it is run independently on each controller and not system-wide on the RF Group Leader. In detail, the threshold is defined by each AP transmit power represented in dBm , minus the constant value of 17dBm, minus the user-configurable Coverage profile value this value is defaulted to 12 dB and is detailed on page The client SNR threshold value is the absolute value positive number of the result of this equation.
Each controller runs the Coverage Hole Detection and Correction algorithm for each radio on each of its APs every three minutes the default value of seconds can be changed. It is important to note that volatile environments can result in the TPC algorithm turning the power down at subsequent algorithm runs.
There is an alternative approach that I would not be surprised to see some manufacturers start to more seriously consider: single channel architecture yep Note that this is used by a wireless systems specifically designed to operate in an SCA mode, you can't just flip all of your existing APs on to the same channel.
Some manufacturers already provide an SCA solution, though they are currently regarded in some quarters as being something of a 'niche', 'non-standard' solution. I believe it has more chance of delivering the promise of Many MCA solutions will have to compromise by reducing channel widths and negate a significant advantage that WiFi gurus out there will no doubt be able to plan and tweak their WiFi networks to the nth degree and get a super-high throughput network operating on MCA.
They will no doubt achieve excellent results. They came from someone within Cisco that is focused on wireless. The explanation though, makes sense. Jeff Rensink pointed out in the comments below that TPC will also increase power levels. Read his comment below as he makes some very valid points.
The NDP reference and accompanying link in his comment is fairly interesting. I set it up in my home office and only maintained about 10 feet separation from the APs. Ideally, I would test it with the APs a lot farther apart, but I did put some barriers around the APs to give some extra attenuation to the signal.
I also only did testing on the 5GHz band. I disabled all of the 2. Blasting 5GHz is less disruptive to their home wireless networks than 2. This particular controller is running 7.The time spent listening on each channel is a function of the non-configurable 50 ms scan time plus, the 10ms it takes to switch channels and number of channels to be scanned. This can come in handy when you have an AP fail and need the other APs to increase their transmit power to fill the gap that exists since that failed AP is no longer servicing clients. The Need For TPC If you have been around wireless long enough, you have probably dealt with wireless installs where all of the access points AP were functioning autonomously. The subsequent sections reference the resulting page [Wireless Token ring was faster, providing 16mbps LAN speeds, compared to the paltry 10mbps of Ethernet. Some manufacturers already provide an SCA solution, though they are currently regarded in some quarters as being something of a 'niche', 'non-standard' solution. It is very important to power here that RF Grouping works per radio type. Weighting is given to APs on their operating channels such that channel adjustments are made locally, dampening changes to prevent the domino effect whereby a assignment change. This can be done through the controller web interface if you select Flu report vancouver bc General and then input a common Group Name value would trigger system-wide channel alterations. The max power an AP can transmit differs by band, and in 5 GHz level be lowest in the UNii1 band channelshigher in Unii2 and Unii2eand highest in Unii3 The number of.
Channel mode is a good choice for High Density Deployments - as this will minimize co-channel interference, while Maximizing coverage and signal between 2 AP's on the same channel. Well there is. The reality is much more complex. There is an advanced CLI command that shows you everything you need in one place.
The series-based controllers support a maximum of 25 access points, so you can have up to 20 of these controllers in an RF group. To wrap up this discussion, This field only indicates the time in seconds since the algorithm last ran and not necessarily the last time a new power assignment was made. Using Channel mode increases the power significantly. From above - we could get good coverage with 3 of the 6 AP's.
The Solution? If the AP is set to a static channel or power it will be listed as User. Each WLC will prioritize the Group Identifier values from its neighbors based first on this counter value and then, in the event of a counter value tie, on the MAC address. It is important to note that volatile environments can result in the TPC algorithm turning the power down at subsequent algorithm runs. In turn, such behavior can have systemic impact on the wireless network whereby clients are perceived to experience poor SNR because they have failed to roam eventually resulting in a coverage hole detection. These values are then used by the Group Leader to determine if another channel schema will result in at least a bettering of the worst performing AP by 5dB SNR or more.