Catalyst 9115e only one active connector antenna for 2.4

[wkamil123]

Hello

I have an issue with a 9115E AP where for 2.4 radio is active only B connector. The question is how to activate others 4 connectors.

Is this model has any limitations?

My installation and AP use is that two antennas are installed in two different rooms, connected to the same AP and it works on AP 1852E.

Kamil

[marce1000]

     - Check if the AP is getting sufficient power , bu scrutinizing a console boot , or just after boot connect to it and issue the command show logging , look for error message related to power , if any

 M.

[wkamil123]

Hello @marce1000 

This AP utilize 20,2W.

Kamil 

[Leo Laohoo]

Get 3 of the same antennas and disable 5 Ghz.  

Catalyst 9115AXE Supported Antennas

If the user insist on using only one antenna then stop using the AP.  

1. Using only one antenna connection (instead of four) will risk permanently damaging the radio
2. Using only one antenna connection (instead of four) guarantees really bad WiFi coverage & customer experience.  

[wkamil123]

Hello @Leo Laohoo 

We have tested on all four antenna connected and when one antenna from B connector was detached, the 2,4 signal was very poor.

This solution worked on 1852E, where two antennas was installed in separated rooms and connected to A and B connectors.
AP 1852E is a 3x3 MIMO and D connector is only for 5GHz radio.
AP 9115E is 4x4 MIMO so all four connectors works in a dual-band radio.

Kamil

[David Ritter]

You have a single antenna system..  because only ONE antenna serves the client.  one in each room.

thus your protocol is automaticly restricted to 802.11 bg or 802.11a.  not n.ac.ax max thruput 53mbps.

all other protocols require multiple streams and/or beam forming 

Buy another AP.

[MarshallT23]

Maybe I can bring some clarity to the conversation:

1) The AP in question is used in a back area in a store in refrigerated store room and a deep freeze store room (-23C/ -9F ) - 2 antenna pushed thorough the insulation barriers with antenna cable 1m in lenght.

2) Throughput is not a high priority, we use radio scanners to check inventory in these places. 1 MB/s max is only needed with maybe 2-3 clients which operate only on 2.4GHz radios a/b/g/n

3) 5 GHz was disabled along with AX functionality on the SSID and other C and D slot identical antennas were added just for testing, nothing changed. Only B slot is transmitting 2.4GHz signal all others at 5GHz.

[Rich R]

According to https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9100ax-access-points/deployment-guide-c07-741977.html#_Toc3418541 all 4 connectors are dual-band so it probably comes down to configuration.

What WLC and software version are you using?

[MarshallT23]

Hi Rich,

We are using the Catalyst 9800-L controller with version 17.9.3

wkamil123 has already checked pretty well and we don't use any custom RF profile policies/ tags, mostly default for theses.

[wkamil123]

Hello guys,

thank for all us to interest in this thread and some explanation.

Cisco AP 9115E and 9120E transmit 2.4GHz radio only on connector B, there are no information in Cisco documentation about it.

We recreated the communication tests which confirmed that only connector B is active for 2.4. Also ekahau shows a worse 2.4 GHz signal for the Cisco AP 9115E. 

The 9120E has Antenna Self-Identification, which allows you to recognize the type of screwed-in antenna, and probably also detects its absence, and then the transmitter turns off and emits no signal at all.

 Both 9115, 9120 and 1850 use all connectors to transmit and receive signals in the 2.4 and 5 GHz bands. These are 4x4:4 devices -> 4 transmitting antennas x 4 receiving antennas: 4 spatial streams. In the case of 9115, there is a limitation that the Bluetooth module that is built into this AP also uses one of the connectors and if we want to use BLE, the AP switches to 3x3 mode in the 2.4GHz band, because the fourth antenna is used for Bluetooth. This only applies to 2.4GHz. In the case of 9120, there is no such limitation, because the Bluetooth module has a dedicated built-in antenna/independent of external connectors.

Regards Kamil

[Rich R]

@wkamil123 that info seems to be contradictory!
First you say: "Cisco AP 9115E and 9120E transmit 2.4GHz radio only on connector B" then you say: "Both 9115, 9120 and 1850 use all connectors to transmit and receive signals in the 2.4 and 5 GHz bands"
So first you say 2.4Ghz only uses 1 antenna (B) then you say it uses 4 or 3 antenna depending on BLE config! 
Those statements cannot both be correct - so which is it?

As @JPavonM says - have you validated your conclusions in any way with Cisco TAC and/or Wireless Networks Business Unit?  Because if it is true that the AP only uses 1 connector for 2.4GHZ, then it contradicts the product documentation and would be a fairly serious fundamental problem with the product which would require a documentation bug to update the product documentation and potentially also a field notice to alert customers.

Note the use of antenna 4/D for BLE is already documented at the link I provided in my previous reply (Fig 38) and as you say this explains that the AP switches to 3x3 mode for 2.4GHz but this still means that Cisco expect the AP to use the first 3 antenna connectors for 2.4GHz.

[MarshallT23]

Hi Rich,

Kamil is referring to the documentation about these APs that all 3 of them transmit 4x4 connection on 2.4GHz without BLE enabled. 

From our testing, in house, we can only get 1 connector to transmit 2.4GHz - connector B - for 9115E and 9120E. We are using Cisco branded antenna and 3rd party in our testing.


@JPavonM No, There is no confirmation or case taken up by TAC/BU, at this time.

[JPavonM]

@wkamil123 is this information validated by TAC/BU?
If so, this is something Cisco might inform to customers as this is extremely important to know for the designs and deployments.

Regards.

[JPavonM]

Then as @Rich R said, and assuming this would be true, cisco should inform all customers, so my recommendation is to open a TAC case and ask about this behavior to TAC/BU engineers so they can confirm it ir not, or if this is some hardware issue in your AP's lot.

[wkamil123]

@Rich R  @JPavonM  

My sentence is based on testing purpose and that is true. The second part of sentence is from Cisco technical solution architect of local office (it's starts from ....Both 9115, 9120 and 1850) and that is true based on official date sheet.

From a marketing perspective, the answer was correct, but he couldn't write it directly in the e-mail. You know what I mean.