Let's improve this 45Km Link!


#1

Hi Community.

We deployed our first B5c Backhaul in a 45km link in Argentina, i’m going to use this post to give you all the images showing link information so we can Exchange information and try to improve this link. The first images are going to be from the AP Side.

The next images are from the station side

This last image is the throughput capacity of the link


#2

Things to talk about. I configured the 75/25 because the clients need a lot of Download traffic more than upload as usual

Why i got a stream down always? the 4 stream in the AP TX and Client RX is always down.

What about the target receive power calculation on the station side? it says -98db!!

What you guys would recommend to change to improve this link?


#3

Hi Luis. You can calculate what to expect in terms of PHY performance based on the per chain SNR: http://backhaul.help.mimosa.co/backhaul-faq-snr-mcs

In this case, the Dashboard MIMO Status panel shows that the SNR ranges from 17 to 27 dB, and that the MCS rates are fluctuating between 4 and 5 based on the interference levels. Tip: while tuning, look at these values on both sides to determine which side of the link could be improved.

The Dashboard Performance panel also contains the Packet Error Rate (PER), which is not shown in the screen captures, but would likely explain the PHY rate asymmetry.

For the reasons above, you may want to try a single 80 MHz channel, which benefits from an additional 3 dB internal signal processing gain, to achieve higher MCS and more symmetric PHY performance.

One or more streams may not be used if the PHY can not support them in one direction or the other.

The signal target is calculated based on Free Space Path Loss and the EIRP from the AP. If the antenna gain or GPS coordinates are inaccurate (or if the actual gain is different on each side), then this value will be affected.

We recently published an RF Tuning Guide that contains links to more information about each of these topics: http://backhaul.help.mimosa.co/backhaul-installation-rf-tuning.


#4

Hello Luis, thanks for sharing your link information. Congrats to a good signal on your long link! I have a few questions for you:

  1. How does your Fresnel Zone clearance look over that distance? Can you post a photo of the link budget showing this? What are your installation heights on both ends?

  2. What is your EIRP limit for your country in this frequency range?

  3. It looks like your channel range seems a bit noisy for optimal performance. Do you have local noise in your channel space or is it somewhere along the link? It looks like there is quite a bit of noise on the AP end toward the upper 5200 range. On the client end, it is a high noise floor across both channels. This is probably giving you a lower SNR which will limit your capacity significantly.

I’d love to hear about your tuning of this link as it is very interesting. Thanks in advance for your information!


#5

Chris, thanks for sharing these links. I have found them to be very helpful in the past and they demonstrate a great engineering foundation for your company. Keep the good (techy) stuff coming as it makes us “RF nerds” very happy to have great reading material like this! :smile:

I’ve already commented to others about how your company gives us a “look under the hood” whereas other equipment providers like to give you a “black box” view. This extra engineering data definitely makes troubleshooting link problems much easier.


#6

Hi Guys, thanks for the info, i’m starting today with the tunning on the Link.

To answer your questions Kyle, Limits and Argentina can’t be in a same sentence :confused: a lot of people uses unlicensed band with no power limitations nobody care about them, so you must always find holes in the spectrum and do the best you can.

The Freznel Zone is very good, i’ll show you the link planning from Mimosa cloud.

I would update this ASAP

Regards


#7

Do i have to put always an end as a station? or is a way to have individual configuration on each side?


#8

Could you please explain me this a Little more?


#9

Each end of a link must be assigned one of two wireless modes: AP or Station (STA). The STA inherits many settings automatically from the AP through beacons:

  • Channel(s)
  • Channel Width(s)
  • Tx Power(s)
  • Antenna Gain (for EIRP calculation)
  • TDMA Gender (inherits opposite value)
  • TDMA Window (2/4/8 ms)
  • TDMA Traffic Split (50/50, 75/25, 25/75)

This aspect of the Mimosa wireless protocol was designed to simplify configuration and eliminate unnecessary steps such as having to enter the same data twice on both radios. The configuration exchange helps to eliminate input errors, and helps with link recovery in case of problems.

Either side of the link can be the AP or STA, but we usually recommend that the AP be placed near the bandwidth source (upstream), such that it is accessible in the event that configuration changes are necessary in response to interference that affects the link.


#10

In this document (http://backhaul.help.mimosa.co/backhaul-ug-mimo-status), we describe the difference between Chains and Streams, and how they behave in noise conditions.

Chains represent the physical medium (RF Tx/Rx values), while Streams represent data. Chains and Streams are not necessarily correlated one to one because the Rate Adaptation algorithm may periodically increase or decrease the number of data streams sent over the physical medium when reacting to interference.

Rate Adaptation dynamically adjusts both the MCS and the number of streams depending on RF conditions. Poor RF conditions (i.e. interference) causes PER to increase. PER and MCS are inversely correlated meaning that as PER increases, MCS decreases and vice versa.

Single channel mode usually uses 2 streams, but may drop to one stream if RF conditions are poor. Dual channel mode uses up to 4 streams. You may also see the number of streams change periodically because of tests that Rate Adaptation performs to optimize performance. This is expected and normal.


#11

Hi Guys

Chris thank you very much for your answers, everything you said is so clear, i have to say that the support you guys give is priceless.

I come to the conclusión with this link that i’m having some obstacle or interference in the path, 'ill try to move the AP side of the link to another tower this month and see if i can avoid this.

Thank you very much for the time and the info.

Best Regards


#12

Congratulations Luis.@Luis
Gracias por compartir sus resultados con todos luis. es muy importante que el intercambio de experiencias con radios mimosa B5c. aquí en Porto Alegre,Río Grande do Sul, Estamos probando esta radio con grandes resultados.
Saludos desde Brasil.


#13

Luis Hello , nice to meet people from Argentina , I live in Argentina . at this time I want to replace my radios AF5X by mimosa radios, you would like to contact you Luis . are two links, one of KM 62 and KM 23 next


#14

Hi everybody!! we are back, i’m going to deploy the mimosa B5c again on the field but first i decide to do some lab test.

Everything started ok till i hit the mother of the walls!!! in the AP side the 4 chains has excellent RX and SNR values but in the Station side i can’t get the 4 chains working, one of them (always the same one) gets no values of Rx and SNR, is this a possibility of the lab test? i have the 2 B5c connected with RF cables with the lowest TX power possible (-7)

Here are some screens, hope you can guide me before i put this two on production.

Best Regards!



#15

Hola Luis,

Podrías especificar que antenas tienes montadas para el Lab? Para ver en que rango de frecuencia traabaja la antena, y que el canal seleccionado (5180) no esté fuera del rango aceptado por la antena.

De todas formas creo que la distancia de prueba es muy corta.
También prueba de cambiar el TDMA a Auto, en vez de 2ms.

Saludos!!


#16

Hola Manuel

No tengo antenas colocadas, hice las pruebas como se recomienda en el FAQ de Mimosa y probe distintos TDMA y diferentes frecuencias siempre obtengo el mismo resultado.

#########

Hi Manuel

I have no placed antennas. I did the tests as recommended in the Mimosa FAQ and probe various different frequencies and TDMA values and always get the same result.


#17

No answers? come on community help me here!


#18

Ola Luis,
Bueno , espectacular actuación este enlace 45km . los consejos que se puede obtener es el uso de los 4 ms ventana TDMA , lo que ayudará en gran medida la estabilidad del enlace. Aquí he conseguido unos resultados perfectos utilizando la radio B5c , ya que el vínculo del proyecto , y sólo entonces puesto en producción . la proporción de energía , en realidad tiene una fuerte influencia en el enlace . aquí no utiizo por encima de 22dbm , por razones de rendimiento.el rendimiento final del enlace es excelente.
Saludos.


#19

Hola Luis, soy de Argentina y también tengo que armar un enlace con mimosa con 45km, ¿al final como te fue? ¿cuantos mb podes pasar? Saludos.