PMP450 Release 25.0 not only adds support for three component carriers, but also the additional flexibility that allows an operator, if they want, to direct selected 450v SMs to only use a subset of the component carriers on a 450v sector for traffic.
An operator could envision scenarios where rather than all 2x2 SMs using two CCs and all 4x4 SMs using three CCs, it could be preferable instead to use a lower number of CCs for traffic on some of these 450v SMs. This saves more bandwidth for the older single CC capable SMs in the sector. To make best use of three component carriers, it’s important to understand how an operator can control both the particular frequency that an SM tries to attach on the air interface with, as well as which frequencies an operator might want to use or not use, on a per-SM basis, for traffic. As described in the release notes, this software contains code that, in most cases, will automatically select the optimal carrier that an SM should lock onto and use. So in most cases, these more complicated procedures described in this article are no longer necessary. See the release notes for most of the necessary details for controlling these things. For the remaining use cases, how to control these things is best described with example use cases. All these use case procedures shown here avoid removing frequencies from the scan list that the SM actively used to attach. Simpler procedures for moving SMs could be created by removing the current primary from the SMs scan list and forcing a new scan and reattachment, but such procedures would carry the risk of no fallback to the prior frequency should any unexpected issues be seen when trying to attach to a different frequency. All the examples shown below assume a starting condition of all applicable scan frequencies are selected on all SMs.
Example 1
Operator’s 450v sector has one 5 GHz CC and one U-NII-5 6 GHz CC that supports 450b6 SMs. The sector has a mixture of different SM types (2x2, 4x4, and single frequency 450b/450b6/450/450i SMs). All the 2x2 SMs are currently on 6 GHz. The goal is to add a second component carrier to 5 GHz, move some but not all of the 2x2 SMs from 6 GHz to 5 GHz, then finally try to force a re-balance of the older 5 GHz single CC SMs between the two 5 GHz component carriers, as well as a re-balance of the 450b6 SMs between the three different component carriers.
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Identify a center frequency that is close enough to the existing 5 GHz component carrier 1 frequency such that the entire transmission spectrum of both 5 GHz component carriers spans 140 MHz or less.
The Logs > AFC GUI page of the AP can help identify clean channels.
Identify the subset of 2x2 SMs that we do not want to move to 5 GHz. On these SMs, remove both 5 GHz frequencies from their scan lists. Now to force the remaining subset of 2x2 SMs from 6 GHz to 5 GHz; from the Configuration > Radio page of AP GUI, temporarily set the center frequency of component carrier 2 (assuming this is the 6 GHz component carrier) to none. Immediately after setting this 6 GHz component carrier frequency to none, map the third component carrier to the 5 GHz carrier and change it’s center frequency from none to the newly selected second 5 GHz component carrier. Setting up this third carrier right after setting the second component carrier to none avoids an additional set of dropped sessions.
If other secondary or tertiary color codes have been configured on the SMs, it’s a good idea to either remove those while performing this step, or set a subscriber color code rescan timer on the AP to force these SMs back to this AP, should they temporarily pickup another AP.
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Once the 2x2 SMs that we desire to move to 5 GHz have re-registered onto 5 GHz, component carrier 2’s 6 GHz center frequency can be reconfigured and saved.
This will result in another set of session drops on all SMs on the sector.
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At this point in time, all the SMs are back on the air interface, but most, or likely all, of the older single CC 5 GHz SMs will be registered on CC1 only, with few or none on CC3. The 450b6 radios will be either on CC1 or CC2, with few or none on CC3. To perform this re-balancing, an operator can issue a Tools → Sessions → “Local” “Drop selected Session”, an SM at a time or a few at a time. See the Improved load balancing for legacy SMs under a 450v feature description in the 24.2.2 Release Notes for more details. That feature description contains a procedure, with the “second method” procedure being the recommended steps, to force rescans a few SMs at a time.
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The end results of this Example 1 is, three component carriers, two of them at 5 GHz, one at 6 GHz, with the 4x4 SMs making use of all three component carriers, the 2x2 SMs split with some of them using both CCs of 5 GHz and others using the single 6 GHz CC, the remaining older 5 GHz only SMs pseudo-balanced between the two 5 GHz component carriers based on the number of SMs per CC and the relative strength of the signals between the two 5 GHz CCs. Similarly, the 450b6 radios will now be balanced between the three component carriers based on differences in RSSI between the three CCs, and the number of SMs using each CC.
Example 2
Operator already has three component carriers configured, with two of them on 5 GHz and one of them on U-NII-5 6 GHz. The goal is to move one of the two 5 GHz component carriers to 6 GHz, move any 2x2 SMs still on 5 GHz to 6 GHz, and move any 450b6 radios still on 5 GHz, to 6 GHz. Sector has a mixture of different SM types (2x2, 4x4, and single frequency 450b/450/450i SMs).
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This procedure is similar to the previous procedure, with one important difference: It’s a best practice here to make sure that all the older single CC capable 5 GHz SMs, 450b6 SMs, and 2x2 SMs still on 5 GHz prior to this move, are using the 5 GHz component carrier that will remain on 5 GHz as their primary frequency prior to the move operation.
For this example, the center frequencies 5770, 5810, and 6200 are used as the starting configuration center frequencies, with 5810 being the frequency we want to replace with an additional 6 GHz frequency. From the Configuration → Radio page of the AP, find the component carrier currently configured as 5810 and set its center frequency to none.
If other secondary or tertiary color codes have been configured on the SMs, it’s a good idea to either remove those while performing this step, or set a subscriber color code rescan timer on the AP to force these SMs back to this AP, should they temporarily pickup another AP.
- All SMs will drop off the air interface. Any SM that had 5810 as its primary frequency will now use 5770 or 6200 as its primary frequency. (if any difficulties are seen with re-registrations at this point, a simple fallback is to reconfigure the 5810 component carrier back to 5810).
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Once it’s confirmed that all SMs have re-registered (at either 5770 or 6200):
- If this sector does not contain any 450b6 radios, the 2x2s can easily be moved with simple session drops on just these SMs, using the improved AP evaluation code: Set the previously disabled component carrier to a new selected 6 GHz component carrier and save. Configuring this new 6 GHz component carrier will force session drops on all SMs, but will not, by itself, force the 2x2 SMs to the 6 GHz carrier. As the 2x2 SMs re-register, force session drops of them via Tools → Sessions → “Local” Drop Selected Sessions. Unlike the procedure for load balancing single CC SMs as described in the previous example, the timing here of each drop is not critical. They can be dropped as they re-register one at a time, or done in rapid succession at a later time.
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If, on the other hand, this sector contains 2x2 SMs and 450b6 SMs, and we want to move them all to 6 GHz, then the cleanest method would be to force the move by temporarily disabling 5 GHz: Set the previously disabled component carrier to a new selected 6 GHz component carrier and save. Configuring this new 6 GHz component carrier will force session drops on all SMs, but will not, by itself, force the 2x2 SMs to the 6 GHz carrier. To do this, as soon as the new 6 GHz CC has been configured, take the remaining 5 GHz component carrier on the AP and set it’s center frequency temporarily from 5770 to none. Doing this right after configuring the second 6 GHz component carrier will avoid a second set of dropped sessions. Once the 2x2 SMs and 450b6 SMs have all re- registered onto 6 GHz, re-enable the remaining 5 GHz 5770 component carrier by changing it’s frequency from none back to 5770. All SMs will briefly drop off the air interface, then re-register.
For these examples, once the procedure is finished and all the SMs are on the component carriers as desired, an operator can, optionally, go into each old “single CC capble” SM or each 2x2 SM and uncheck the frequencies currently not in use by that SM. This will prevent an undesired registration on that component carrier when a full SM scan is triggered at some point in the future by an unexpected event.
Also, for both of the above examples, at the end of the example an operator could, optionally, go into selected 2x2 or 4x4 SMs and clear one or two currently in use component carriers if an operator wants an SM to only use 1 or 2 component carriers instead of 2 or 3. This is explained in the Virtual AP feature description. A session drop > Local after the deselection is necessary for the SM to stop using that CC. As mentioned in that description, it’s a best practice to make sure the SM is not using this frequency as it’s primary frequency before deselecting it.