The ePMP1000' Transmit Power

Hello Cambium technical team,

I have a problem with ePMP 1000 deivce, it's as follow:

The transmit power value is not effectible although I changed many times, it's aroud 9-10 dBm.

Can you tell me some your sharing about this problem ?

Thank you so much!

How are you trying to use the radio ? Is this a 2 or 5 GHz radio, channel width ect. The radios have different rules depending on mode of operation, channel size, and country code

Hello Chris

This is 5GHz Connectorized Radio with Sync.

Channel Bandwidth = 40 MHz

Coutry Code: Other

Operating Mode: TDD, Subscriber Module

I tried to set the transmit power so much times, but it seem to be not effective, the value is not changed. 

I am finding some  screenshot to share for you.

Thank you so much for your replying!

Hi vantienphap,

Actually there are three mechanisms on ePMP boards which affect TX Power:

1. Regulatory,
2. ATPC,
3. Dynamic TX Power.
 
ATPC works only in TDD/TDD PTP mode.

1. Regulatory - limits transmitter power in accordance with the requirements of the government agencies depending on the Country Code. It depends on the Country Code, band, mode (PMP / PTP).

 Regulatory limits Tx Power both on AP and on the SM.

2. ATPC - Automatic Transmit Power Control.

ATPC Settings on AP:

atpc.jpeg

 AP will perform control over TX Power on SM to get UL RSSI the same as configured in Subscriber Module Target Receive Level.

Tx Power on SMs can be configured in two ways:

- Auto - ATPC will completely control Tx Power on SM.

- Manual - in manual mode ATPC will controll Tx Power too but configured value will be upper limit for Tx Power on SM.sm_pow.jpeg

3. Dynamic Tx Power - Tx Power limitation caused by quality indicators of transceiver system.

Tx power limitation is the result of increased error vector magnitude (EVM - Error Vector Magnitude) at higher MCS with more complex modulation types. Limitation has frequency dependency, and also depends on the device type. For each ePMP device there are separate tables with Dynamic Tx Power vs MCS.

 

Thank you.

Hello Fedor,

I see what you share, but I still have understood the meaning of Manual mode. You mean, in Manual mode when we set the transmit power value, that is upper limit value, for example:

If we set the transmit power value is 20, the transmit power will be any values less 20dBm than.

So, in this case, I have to remove the ATPC on AP and set manually transmit power at SM to get a expect value, don't I ?

Thank you so much for your sharing

Yes, in Manual Mode ATPC will reduce Tx Power if it will be necessary.

But ATPC will be not allowed to set value higher than value configured on UI.

If you want to get higher Tx Power on SM you should configure higher Subscriber Module Target Receive Level on AP.

But please note that in that case you will have higher secondary interferer if multi-sector site topology is used.

Please provide screenshots Monitor -> Wireless pages from AP and SM,  Home page from SM and Configure -> Radio from AP and we will review your case in details.

Thank you.

Hello Fedor

I am going to site to check and take screenshot for you, tomorrow

Thanh you for your help!

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Hello Fedor,

I have several  informations for you.

Yesterday, I was on-site with my customer to solve problem "ePMP Link' Throughput is not stable ", I will introduce some imformations about link:

- Central ePMP: APTTPTP, Transit ePMP: SMTCPTP

- 14 Camera' load were born by this link, its distance is around 3-5 km.

- ePMPs is with Dish antennas and GPS

- There are totally 34 integrated ePMP connecting to APTTPTP and SMTCPTP with difference locations 

- Each camera works with 3-4 Mbps.

Symptom: Uplink throughput have been not stable.

I tried to change Transmit Power at AP and SM but it's still  not effective. 

I saw that, Link Quality and Link Capacity is very good, but I don't understand Why throughput is not stable. 

In this case, my opinion, almost camera data is from Transit ePMP to Central ePMP, so I should change Downlink/Uplink Ratio to 30/70, Should not I ?

 

Also, I would like to know some knowledges about link:

- What is the meaning of Wireless Test Link ? Can you please explain elearly ?

- Why the downlink' throughput is higher uplink' throughput than. 

Could you please give some advices to improve this link as soon as possible ? My customer is in a hurry to hand over for their partner.

Thank you so much!

have you tried flexiable mode ?

your AP normally tells your SM how loud to talk, if you want your uplink louder, decrease your target recivie level from the default 60 to 55, and work your way down.   as pointed out above, if your in a GPS reuse setting, becareful. 

the flex mode will allow the gear to change the ratio to do what it needs to move your traffic.   a fix mode with that many cameras and that data rate per camera can be done, but your pushing th gear limits.

if you can screen shot your performance screen and post for us that would help us help you. 

please also screen shot your config screens and we can help you make the best possible changes to max this link. 

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Hello Chris,

I can not send three images for you. each image is only 3-4 Mb. How to send it.

Hello Chris,

I tried to flexible mode, but it is not effective.

Hi, 

Have you contacted our spport team yet? They can be reached here: http://www.cambiumnetworks.com/support/contact-support/

Sounds like working this through a support engineer will be the best way to solve this. 

Thanks,

Sriram

Hi Sri,

I have just opened case on your site.

Thank you so much!

Hi Sri,

The value uplink' throughput at page "Wireless Link Test" of  the ePMP AP is only for one link or all link.

Thank you so much 

Hi Sri 

I send you some images to refer.

Thank you for your help!

Can you try updating to 2.6, or even the newest beta and do some tests. Then try using a 20MHz channel width and do some tests?

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Hi vantienphap,

You have provided only part of required information, but I will try to describe what I see.

Your SM module has 22 dBm Tx Power on 5425 MHz channel with UL MCS 13.

22 dBm is Dynamic Tx Power limitation (please find in tables I've provided earlier).

SM has DL RSSI - 61 dBm and SNR 31. It is very close to MCS 15.

And I can assume DL RSSI is jumping between MCS 14 and 15 that has negative influence on Throughput.

UL MCS on SM is 13 it means that there is some interferer(noise) on SM side.

In ideal case Wireless link should be symmetric (RSSI and MCS).

There is no information about other SMs in sector but I can assume that their UL RSSIs are worth than that one has and that is the reason why you have low UL Throughput during Wireless Link Test.

Please try 20 MHz channel, that will decrease interferer influence.

Also try to find optimal ratio for your link: 50/50 or flexible or even 30/70.

But first of all you should be sure that every SM has high MCS in  UL and DL.

Also I would like to recommend you to limit Max MCS value to avoid hopping between MCSs in case it is not possible to get MCS 15 in DL or UL.

Thank you.

@Fedor

Could the tables in the previous post be updated with the Epmp2000 parameters?

I'm specifically interested to know if the Epmp2000 can transmit with more than 18dbm@MCS15 across the band. 

Thanks

Guilherme.

They can transmit at 27 Db @mcs15.

1 Like

Sounds a bit on the overkill side . 

I like it! :)