Wireless Access

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Any time you have multiple radios within the same RF space operating in the same channel space, you have the possibility of causing channel re-use issues.  In your example, assuming clients are all connecting/communicating at 80 MHz, then only one device can be communicating on the 80 MHz channel that encompasses the 20 MHz channels 149 through 161 at a time.  If you have two radios operating on that same 80 MHz channel, and 50 clients are associating to each, then you've bottlenecked all communication for those 100 clients.

For that environment we'd never recommend using 80 MHz, 40 MHz may be possible depending on the surrounding channel usage, 20 MHz may be required to avoid excessive ACI or CCI.

Using the DFS channels is pretty much a requirement for 80 MHz channels to be useful at any kind of installation density.  Your specific usage of the DFS channels is going to be dependent on incumbent operators in your area and what the majority of the client base is capable of utilizing.

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Thanks for the reply.  It still leaves my questions unanswered.  Here is some follow-up questions:

If the primary channel is 44E for one radio, and the second radio's primary is 48E, and they share the same 80MHZ bandwidth, is the controller doing some sort of time-slicing as to not cause co-channel interference?

Below is a pic of the environment.  Interference is less than .3%.....  But, channel utilization/channel busy is higher than I like to see:

Matt

Any time you have multiple radios within the same RF space operating in the same channel space, you have the possibility of causing channel re-use issues.  In your example, assuming clients are all connecting/communicating at 80 MHz, then only one device can be communicating on the 80 MHz channel that encompasses the 20 MHz channels 149 through 161 at a time.  If you have two radios operating on that same 80 MHz channel, and 50 clients are associating to each, then you've bottlenecked all communication for those 100 clients.

For that environment we'd never recommend using 80 MHz, 40 MHz may be possible depending on the surrounding channel usage, 20 MHz may be required to avoid excessive ACI or CCI.

Using the DFS channels is pretty much a requirement for 80 MHz channels to be useful at any kind of installation density.  Your specific usage of the DFS channels is going to be dependent on incumbent operators in your area and what the majority of the client base is capable of utilizing.

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

As mentioned by @cjoseph, interference isn't counting in "valid" Wi-Fi signals.  That information goes into the channel utilization/busy buckets and the primary time slicing is standard 802.11 channel contention behaviors.

Your 80 MHz channel configuration is killing performance in that room.

For a dense deployment, I always start with 20 MHz and then only move to 40 MHz if the environment allows.  80 MHz channels are useful for isolated environments, residential, and 6 GHz.

Thanks for the reply.  It still leaves my questions unanswered.  Here is some follow-up questions:

If the primary channel is 44E for one radio, and the second radio's primary is 48E, and they share the same 80MHZ bandwidth, is the controller doing some sort of time-slicing as to not cause co-channel interference?

Below is a pic of the environment.  Interference is less than .3%.....  But, channel utilization/channel busy is higher than I like to see:

Matt

Any time you have multiple radios within the same RF space operating in the same channel space, you have the possibility of causing channel re-use issues.  In your example, assuming clients are all connecting/communicating at 80 MHz, then only one device can be communicating on the 80 MHz channel that encompasses the 20 MHz channels 149 through 161 at a time.  If you have two radios operating on that same 80 MHz channel, and 50 clients are associating to each, then you've bottlenecked all communication for those 100 clients.

For that environment we'd never recommend using 80 MHz, 40 MHz may be possible depending on the surrounding channel usage, 20 MHz may be required to avoid excessive ACI or CCI.

Using the DFS channels is pretty much a requirement for 80 MHz channels to be useful at any kind of installation density.  Your specific usage of the DFS channels is going to be dependent on incumbent operators in your area and what the majority of the client base is capable of utilizing.

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Also...your comment "Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle" is a bit problematic.  The APs have a specific installation orientation, and wall mounting of an omnidirectional AP, where the AP is oriented vertically rather than horizontally, is going to mean the AP will not operate as well as it could.  The antennas are omnidirectional with an electrical down-tilt, so with the APs wall-mounted the majority of the signal is parallel with the wall, going into the floor and the ceiling.

If ceiling mounting or horizontal wall mounting with a 3rd party mounting adapter isn't possible, you should be installing one of the external antenna APs so that the antennas can be oriented to provide proper coverage of the desired area.

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

EDIT:  I type a wall of text just to see that @chulcher has already responded twice.  Great...

I will talk in general:

• Wall- mounting access points that are designed to be ceiling mounted is only a good idea, if you have wall mounts that orient them properly.  Otherwise you will create coverage patterns much more narrow than intended.
• If students are having problems connecting, noise floor is one thing that should be looked at, but RF utilization, especially in group meeting rooms is a better metric of available capacity.  The RF utilization that you should see is individual, but you do not want 60% RF utilization maintained, because that leaves little room for bursting performance.
• The controller can balance client numbers, but it is very conservative unless (1) client has been on the same AP for a set amount of time AND (2) client is seen considerably better on a different AP, which is unlikely in a dense space AND (3) the client numbers between the target AP and the existing AP is great.  Either way, the number of clients on an AP does not directly determine performance, is why client load balancing is not aggressive.
• Noise levels in the -90s means that there is little non-wifi interference in your environment, which is good.  Energy from stray wifi that cannot be decoded is also considered "interference".
• You should not be deploying 80mhz wide channels in a dense environment because (1) You considerably reduce the number of channels available for bandwidth (2) channel bundles that do overlap will decrease the performance of other APs that share the same channels in the same space (3) avoidance of interference or high utilization on affected channels will decrease and overall performance statistically will drop.  You should try 40 or even 20, which statistically overall better performance in a set-it-and-forget-it scenario
• You should definitely allow DFS, because most clients support it these days and you are leaving bandwidth on the table if you do not.  If you see repeated consistent radar hits in the wireless log on specific channels, you can remove them from the regulatory domain profile.  "False" radar hits increase with the width of channels, so 80mhz wide will show more false hits than 40mhz wide and 40 will show more than 20 statistically.
• Chipsets should allow 80mhz DFS channels, if that is what you are asking.

Again, these are general answers to your questions, and you should open a technical support case with TAC or engage with a certified partner to get a specific solution.  Part of deploying wireless is not only the performance, but the complexity of maintaining a solution after initial configuration.  Running 20mhz wide channels with DFS channels allows the most flexibility, and interference mitigation overall.

The high density Validated Reference Design guide here is still valid:  https://community.arubanetworks.com/community-home/artificial-intelligence-tech-corner/viewdocument?DocumentKey=e39f54ac-6361-4b61-8866-e4cfbb578f5f&CommunityKey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&tab=librarydocuments

------------------------------
Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card

Original Message:
Sent: Sep 07, 2023 10:33 AM
From: mbonadie
Subject: 80 MHz channel selection clairification for VHD classrooms

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

Thanks for the wall.....  :)  Here is my take away:

• Oberon Brackets for proper orientation
• Enable DFS 80MHZ channel pairs
• Don't use 80 MHZ channels in VHD environments

I can create a profile just for the room(s) that allows a custom regulatory domain profile for channels/bandwidth.

EDIT:  I type a wall of text just to see that @chulcher has already responded twice.  Great...

I will talk in general:

• Wall- mounting access points that are designed to be ceiling mounted is only a good idea, if you have wall mounts that orient them properly.  Otherwise you will create coverage patterns much more narrow than intended.
• If students are having problems connecting, noise floor is one thing that should be looked at, but RF utilization, especially in group meeting rooms is a better metric of available capacity.  The RF utilization that you should see is individual, but you do not want 60% RF utilization maintained, because that leaves little room for bursting performance.
• The controller can balance client numbers, but it is very conservative unless (1) client has been on the same AP for a set amount of time AND (2) client is seen considerably better on a different AP, which is unlikely in a dense space AND (3) the client numbers between the target AP and the existing AP is great.  Either way, the number of clients on an AP does not directly determine performance, is why client load balancing is not aggressive.
• Noise levels in the -90s means that there is little non-wifi interference in your environment, which is good.  Energy from stray wifi that cannot be decoded is also considered "interference".
• You should not be deploying 80mhz wide channels in a dense environment because (1) You considerably reduce the number of channels available for bandwidth (2) channel bundles that do overlap will decrease the performance of other APs that share the same channels in the same space (3) avoidance of interference or high utilization on affected channels will decrease and overall performance statistically will drop.  You should try 40 or even 20, which statistically overall better performance in a set-it-and-forget-it scenario
• You should definitely allow DFS, because most clients support it these days and you are leaving bandwidth on the table if you do not.  If you see repeated consistent radar hits in the wireless log on specific channels, you can remove them from the regulatory domain profile.  "False" radar hits increase with the width of channels, so 80mhz wide will show more false hits than 40mhz wide and 40 will show more than 20 statistically.
• Chipsets should allow 80mhz DFS channels, if that is what you are asking.

Again, these are general answers to your questions, and you should open a technical support case with TAC or engage with a certified partner to get a specific solution.  Part of deploying wireless is not only the performance, but the complexity of maintaining a solution after initial configuration.  Running 20mhz wide channels with DFS channels allows the most flexibility, and interference mitigation overall.

The high density Validated Reference Design guide here is still valid:  https://community.arubanetworks.com/community-home/artificial-intelligence-tech-corner/viewdocument?DocumentKey=e39f54ac-6361-4b61-8866-e4cfbb578f5f&CommunityKey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&tab=librarydocuments

------------------------------
Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card

Original Message:
Sent: Sep 07, 2023 10:33 AM
From: mbonadie
Subject: 80 MHz channel selection clairification for VHD classrooms

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

• Oberon Brackets are the gold standard.  Another customer wall-mounted APs and ended up with more clients on the floors above and below, and very little coverage in front of the APs.  Using the brackets solved the customer's issue
• Do not use 80mhz channels.  If you just configure the maximum and minimum channel width in the 5ghz radio profile to 20, it will only use 20mhz channels and 80 and 40mhz wide channel pairs will be ignored in the regulatory domain profiles.
• Radical thought: You don't have to create a profile specific for rooms:  You can just deploy 20mhz channels everywhere, make sure you are dropping broadcast and multicast, make the minimum and maximum transmit power to 18 or 15 and call it a day campus-wide.  20mhz channels will allow you to have maximum capacity, and interference avoidance, and you won't be tearing out your hair configuring multiple profiles.  Airmatch will lay out your channel plan based on the environment for the previous 24 hours.  Try it and get your time back.  Monitor the RF utilization at midnight and then when things are really busy to determine how you are doing...

Thanks for the wall.....  :)  Here is my take away:

• Oberon Brackets for proper orientation
• Enable DFS 80MHZ channel pairs
• Don't use 80 MHZ channels in VHD environments

I can create a profile just for the room(s) that allows a custom regulatory domain profile for channels/bandwidth.

EDIT:  I type a wall of text just to see that @chulcher has already responded twice.  Great...

I will talk in general:

• Wall- mounting access points that are designed to be ceiling mounted is only a good idea, if you have wall mounts that orient them properly.  Otherwise you will create coverage patterns much more narrow than intended.
• If students are having problems connecting, noise floor is one thing that should be looked at, but RF utilization, especially in group meeting rooms is a better metric of available capacity.  The RF utilization that you should see is individual, but you do not want 60% RF utilization maintained, because that leaves little room for bursting performance.
• The controller can balance client numbers, but it is very conservative unless (1) client has been on the same AP for a set amount of time AND (2) client is seen considerably better on a different AP, which is unlikely in a dense space AND (3) the client numbers between the target AP and the existing AP is great.  Either way, the number of clients on an AP does not directly determine performance, is why client load balancing is not aggressive.
• Noise levels in the -90s means that there is little non-wifi interference in your environment, which is good.  Energy from stray wifi that cannot be decoded is also considered "interference".
• You should not be deploying 80mhz wide channels in a dense environment because (1) You considerably reduce the number of channels available for bandwidth (2) channel bundles that do overlap will decrease the performance of other APs that share the same channels in the same space (3) avoidance of interference or high utilization on affected channels will decrease and overall performance statistically will drop.  You should try 40 or even 20, which statistically overall better performance in a set-it-and-forget-it scenario
• You should definitely allow DFS, because most clients support it these days and you are leaving bandwidth on the table if you do not.  If you see repeated consistent radar hits in the wireless log on specific channels, you can remove them from the regulatory domain profile.  "False" radar hits increase with the width of channels, so 80mhz wide will show more false hits than 40mhz wide and 40 will show more than 20 statistically.
• Chipsets should allow 80mhz DFS channels, if that is what you are asking.

Again, these are general answers to your questions, and you should open a technical support case with TAC or engage with a certified partner to get a specific solution.  Part of deploying wireless is not only the performance, but the complexity of maintaining a solution after initial configuration.  Running 20mhz wide channels with DFS channels allows the most flexibility, and interference mitigation overall.

The high density Validated Reference Design guide here is still valid:  https://community.arubanetworks.com/community-home/artificial-intelligence-tech-corner/viewdocument?DocumentKey=e39f54ac-6361-4b61-8866-e4cfbb578f5f&CommunityKey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&tab=librarydocuments

------------------------------
Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card

Original Message:
Sent: Sep 07, 2023 10:33 AM
From: mbonadie
Subject: 80 MHz channel selection clairification for VHD classrooms

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt

That's totally radical.  I wish I could but it's not my call!  Doing that would be a major impact change and I have 10k plus APs.  I will say something about it.

Matt

• Oberon Brackets are the gold standard.  Another customer wall-mounted APs and ended up with more clients on the floors above and below, and very little coverage in front of the APs.  Using the brackets solved the customer's issue
• Do not use 80mhz channels.  If you just configure the maximum and minimum channel width in the 5ghz radio profile to 20, it will only use 20mhz channels and 80 and 40mhz wide channel pairs will be ignored in the regulatory domain profiles.
• Radical thought: You don't have to create a profile specific for rooms:  You can just deploy 20mhz channels everywhere, make sure you are dropping broadcast and multicast, make the minimum and maximum transmit power to 18 or 15 and call it a day campus-wide.  20mhz channels will allow you to have maximum capacity, and interference avoidance, and you won't be tearing out your hair configuring multiple profiles.  Airmatch will lay out your channel plan based on the environment for the previous 24 hours.  Try it and get your time back.  Monitor the RF utilization at midnight and then when things are really busy to determine how you are doing...

Thanks for the wall.....  :)  Here is my take away:

• Oberon Brackets for proper orientation
• Enable DFS 80MHZ channel pairs
• Don't use 80 MHZ channels in VHD environments

I can create a profile just for the room(s) that allows a custom regulatory domain profile for channels/bandwidth.

EDIT:  I type a wall of text just to see that @chulcher has already responded twice.  Great...

I will talk in general:

• Wall- mounting access points that are designed to be ceiling mounted is only a good idea, if you have wall mounts that orient them properly.  Otherwise you will create coverage patterns much more narrow than intended.
• If students are having problems connecting, noise floor is one thing that should be looked at, but RF utilization, especially in group meeting rooms is a better metric of available capacity.  The RF utilization that you should see is individual, but you do not want 60% RF utilization maintained, because that leaves little room for bursting performance.
• The controller can balance client numbers, but it is very conservative unless (1) client has been on the same AP for a set amount of time AND (2) client is seen considerably better on a different AP, which is unlikely in a dense space AND (3) the client numbers between the target AP and the existing AP is great.  Either way, the number of clients on an AP does not directly determine performance, is why client load balancing is not aggressive.
• Noise levels in the -90s means that there is little non-wifi interference in your environment, which is good.  Energy from stray wifi that cannot be decoded is also considered "interference".
• You should not be deploying 80mhz wide channels in a dense environment because (1) You considerably reduce the number of channels available for bandwidth (2) channel bundles that do overlap will decrease the performance of other APs that share the same channels in the same space (3) avoidance of interference or high utilization on affected channels will decrease and overall performance statistically will drop.  You should try 40 or even 20, which statistically overall better performance in a set-it-and-forget-it scenario
• You should definitely allow DFS, because most clients support it these days and you are leaving bandwidth on the table if you do not.  If you see repeated consistent radar hits in the wireless log on specific channels, you can remove them from the regulatory domain profile.  "False" radar hits increase with the width of channels, so 80mhz wide will show more false hits than 40mhz wide and 40 will show more than 20 statistically.
• Chipsets should allow 80mhz DFS channels, if that is what you are asking.

Again, these are general answers to your questions, and you should open a technical support case with TAC or engage with a certified partner to get a specific solution.  Part of deploying wireless is not only the performance, but the complexity of maintaining a solution after initial configuration.  Running 20mhz wide channels with DFS channels allows the most flexibility, and interference mitigation overall.

The high density Validated Reference Design guide here is still valid:  https://community.arubanetworks.com/community-home/artificial-intelligence-tech-corner/viewdocument?DocumentKey=e39f54ac-6361-4b61-8866-e4cfbb578f5f&CommunityKey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&tab=librarydocuments

------------------------------
Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

HPE Design and Deploy Guides: https://community.arubanetworks.com/support/migrated-knowledge-base?attachments=&communitykey=dcc83c62-1a3a-4dd8-94dc-92968ea6fff1&pageindex=0&pagesize=12&search=&sort=most_recent&viewtype=card

Original Message:
Sent: Sep 07, 2023 10:33 AM
From: mbonadie
Subject: 80 MHz channel selection clairification for VHD classrooms

Hello-

I have some questions that I hope some experienced experts could weigh in on.  Some back story.  I work in a campus environment with some very large classrooms that can handle 250-400 students.  When approaching RF design for these classrooms I have used AP-345s to take advantage of the dual-5GHz radios for capacity and channel selection flexibility.

During the start of our semester, we usually get trouble tickets from professors that the "students can't connect to TopHat" or something similar, when an outside vendor hosted teaching solution (internet or AWS location) is being used for quizzes/testing. 

One of my classrooms has (4) AP-345s deployed, and usually all but one of them are in dual 5GHz mode.  So, this gives the class (7) 5Ghz channels, and (1) for legacy 2.4Ghz.  Not that it matters too much, but the AP's are wall mounted facing into the room and clients sit in the middle.  Power levels are set correctly, and there is a good noise-floor.  The controller is doing "okay" for balancing the clients, but I do see some AP's getting way more clients then the rest.  All clients seem to be at 80MHz as well. The classroom that reported issues consistently has up to 300-325 connections.

Currently we don't allow the DFS channels to bond for 80MHz, and that only allows 4 channel pairs for the controller to choose from.  I'm noticing channel overlap in this room, but the interference metric is super low. 

Finally, here are my questions:

• If the controller chooses channel 149E for one radio, and the next radio is on 153E, and they are in the same room, and they share the same RF bandwidth, does this cause a problem to the client?  Or, am I missing something about channel reuse?
• Are the chipsets advanced enough yet to allow DFS 80Mhz channel bonding?

Sorry for the long back story.

Matt