Cisco 1852 | Performance issue with 80mhz | Setup issue ?

[Elrick Landon]

Hi to all,

I'm using C3702e (40Mhz) and 1852e (80Mhz) Cisco Wireless controller.

1852 was bought last week, unfortunatelly, i'm not able to reach 80Mhz with it... only a poor 40mhz (300Mbps download/ 450Mbps upload).

Performance of my 1852e is pretty similar to C3702e, so i am disappointed.

C3702 is in Autonomous mode, C1852 with Mobility Express (same things than Autonomous).

I use true gigabyte ISP connexion with C3850 switch (POE+ switch), so there is no power issue.

I'm using Galaxy S8+ for doing my test, it's VHT80 compliant, so able to reach 1,2Gbps bandwidth with wifi ac wave @80Mhz

I join C1852 setup.

I try to change Best in 5Ghz Channel Width to 80Mhz to force it to be @80Mhz but it doesn't change anything.

I precise that the speedtest was done at 2 meters of AP.

I think that's a setup issue, so please advise.

I you have some suggestion to improve/optimise this setup, you are welcome

UPDATE : I was surprised, my Lenovo x280 and i was able to reach 550/570Mbps, but we are still far from 1,2Gbps

Best Regards.

[Elrick Landon]

...

[patoberli]

First of all, what is the Data Rate you achieve with your test clients?
Based on that data rate, remove about 50% and you should have your maximum transmission speed. This of course only without any other signals in the 5 GHz range by any neighbors.
Also important, only test either upload or download, not both directions at the same time.

I suggest you use the freeware software iperf to test, with a LAN attached client as iperf server.

[Elrick Landon]

Hi,

I follow your suggestion with iperf.

Iperf result for Wifi (with Lenovo x280 ----WiFi--- AP1852e -----Wired---- Cisco switch----wired---- PC Test)

Result are very poor for 5Gh/80Mhz

Iperf result for Wifi (with Lenovo x280 ----WiFi--- AP3702e -----Wired---- Cisco switch----wired---- PC Test)

Result are correct for 5Gh/40Mhz

Iperf result for Wifi (with Lenovo x280 ----Wired--- Cisco switch----wired---- PC Test)

Result are normal, interface limited to 1Gbps

As you can see, they are no major difference between 3702e and 1852e.

I hope that 1852e Wireless configuration can be optimized.

What do you think about it?

Best regards.

[MTOMASSINI]

Hello,

Do you know how many spatial streams are on the NICs used ? Usually Phones, Laptops have 2 spatial streams so according to the VHT MCS rates, you cannot achieve the same throughput with 1 spatial stream or 2 and more.

Your AP supports 4x4 MU-MIMO but your phone (and probably your other devices) seems to be limited to  :

Wireless 802.11a/b/g/n/ac 2x2 MU-MIMO

https://www.anandtech.com/show/11285/first-look-samsung-galaxy-s8

On windows, with "netsh wlan show interfaces" the NIC vendor/model is displayed and sometimes the antennas are included in the description.

[patoberli]

As MTOMASSINI wrote, which exact adapter model is built into your Lenovo?
Do you test while the Lenovo is attached to power?

[Elrick Landon]

I checked with iperf, Lenovo attached to power (or not) didn't affect speed transfert.

[Elrick Landon]

Result :

For complete, i do multiple test with iperf, i have result between 280mbit (min.) and 412mbit (max.)

Speed rate change but i don't change anything... laptop was not moved during test, just some few seconds between each test. 

[patoberli]

83% Signal is surprisingly bad and shows other signals in the area disturbing your signal. The Reception/Transmission rate are the previously mentioned "data rate", so you should reach a transmission speed of around 50-60% of that data rate with a >95% Signal quality.
So I would currently say, everything is more or less normal. Only things you can try, update the Intel driver to a newer version and make sure you don't have other APs near on channel 36+40+44+48 (if using 80 MHz channels).

[Elrick Landon]

Hi,

How can i show if i have APs near on channel 36+40+44+48 ?

Best Regards.

[patoberli]

The 1850 sadly lacks CleanAir, but you can use an app on your laptop, for example Acrylic Wi-Fi Home (which is free).
Alternatively you can use this interface on ME: https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-2/b_Mobility_Express_Deployment_guide/b_Mobility_Express_Deployment_guide_chapter_0101.html#task_1E82131ED1124663980E4B2A61243671
There you should note the Channel Utilization, which I think also works without CleanAir APs.

[Elrick Landon]

Many thanks, i will try Acrylic Wi-Fi Home, it seems an interesting application to have ;)

One other question, i use both AP (1852e and 3702e), soon i will be with 2x 1852e.

I use these AP to cover all my house to have WiFi, all AP has the same SSID.

The goal is to move from one AP to other without disconnection and to use the closest one automatically.

Does it have sens to use different channel on each AP? or i can use the same channel in this case?

Best Regards.

[patoberli]

If you use one 1850 as ME Master and the two other APs as subordinates, then this will be all automatically for you configured, depending on various other external influences.

[MTOMASSINI]

From the wlc, the command show ap auto-rf 802.11a <ap_name> should display the neighbors on the 5ghz band.

The signal quality with netsh is not a reliable value (it is not related to a specific RSSI but only a Windows threshold).

I have a .exe  program that you can run from cmd that converts the signal to RSSI :

From the WLC it is the "same" value :

Radio Signal Strength Indicator............ -42 dBm
Signal to Noise Ratio...................... 51 dB