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AF5X useful info - power/sensitivity to achieve certain modulation

[ Edited ]

Hi guys,

As some of you probably already know in order to achieve certain modulation you require enough signal strength to keep it stable. Radio sensitivity information is available in almost all our products' datasheets. However, not all users know that output power also determines what the maximum modulation rate is. airFiber 5X is a very powerful device and every dB matters in order to get maximum throughput and optimize efficiency. So we publish here two tables, one showing suggested maximum Tx Power and another showing radio sensitivity depending on channel width and modulation.

 

AF5-X (remember that maximum output power depends on country code and frequency)

 

Suggested Max TX Power:

 

8x            19-20 dBm

6x            21-22 dBm

4x            23-24 dBm

1-2x        26 dBm

1/4x        26 dBm

 

It means if you want to achieve up to 8x modulation it's highly recommended to use output power up to 20dBm, if you use higher levels, for example 21dBm output power you will be only able to get up to 6X.

 

Sensitivity:

BW (MHz)

Rate

RX Power (dBm)

50

8x

-60

50

6x

-67

50

4x

-74

50

2x

-81

50

1x

-83

 

 

 

40

8x

-61

40

6x

-68

40

4x

-75

40

2x

-82

40

1x

-84

 

 

 

30

8x

-62

30

6x

-69

30

4x

-76

30

2x

-83

30

1x

-85

 

 

 

20

8x

-64

20

6x

-71

20

4x

-78

20

2x

-85

20

1x

-87

 

 

 

10

8x

-66

10

6x

-74

10

4x

-81

10

2x

-88

10

1x

-90

 

Radio sensitivity depends on channel width and modulation, for example if you want to get 8X modulation using 30MHz channel you need a received signal strength of -62dBm or better (like -60dBm, -55dBm, etc...).

 

Maximum EIRP in the United States

 

As mentioned previously maximum EIRP depends on frequency (and country code). Here is a list of maximum EIRP for each UNII band:

 

Band 

Frequency range

max. EIRP (dBm)

 

5.1GHz

5150-5250 MHz

49

5.2GHz

5250-5350 MHz

30

5.4GHz

5470-5600 MHz

5650-5725 MHz

30

5.8GHz

5725-5850 MHz

60

 

Additionally, 5.1GHz band has more rigorous EIRP limits for certain frequencies:

 

Channel bandwidth 

Frequency range

(Band edges in MHz

max. EIRP (dBm)

 

10 MHz

5155-5175

5166-5186

5177-5250

39

44

49

20 MHz

5156-5180

5161-5185

5166-5209

5190-5250

37

39

44

49

30 MHz

5155-5192

5163-5202

5173-5211

5182-5250

37

39

44

49

40 MHz

5155-5204

5165-5219

5180-5228

5189-5250

37

39

44

49

50 MHz

5155-5214

5165-5233

5184-5242

5193-5250

37

39

44

49

 

Important note: It's a good practice to keep a certain fade margin in case of weather changes or other situations that could temporarily affect your link. Recommended fade margin depends on your area and link distance. In most cases it's recommended to keep at least 5dBm of fade margin.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

[ Edited ]

Do you have the recommended TX-Power vs Evm for the AF5/Af5u?  
Do they have the same RF front-end? (therefore i could assume AF5 should be kept under 21dbm[44db EIRP] for 6x operation)

Altough the recieve side of AF5/AF5u seems to be more sensitive than AF5x's (for 30mhz@64Qam), Af5x table indicates -69dbm while AF5 claims to need -73dbm.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

The AF5 for the higher price, has better components and an integrated antenna, that allow it to achieve modulations much, much easier than an AF5X can.  So use the AF5 specs in the datasheets for the AF5 and AF5U.

 

For the AF5, 39 EIRP is the max tx for 10X, 43-45 is the max for 8x.  6X can be achieved at all USA power levels.

 

 

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Salvador,

 

It is UBNT convention to put this information in the datasheet, and indeed that is where it belongs.

 

Can you please get the Datasheet updated.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Hi @guipoletto,

To answer your question for the AF5/AF5U, this information is in the design guide, here:

http://dl.ubnt.com/guides/airfiber/airFiber_AF5_AF5U_DG.pdf
Want to try out new features or fixes before they're released as Stable? Sign up for Beta here: https://help.ubnt.com/hc/en-us/articles/204908664-How-To-Signup-for-Beta-Access
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Re: AF5X useful info - power/sensitivity to achieve certain modulation

[ Edited ]

I still want to see the required SNR per modulation and if it varies, per channel size. You have provided them for the AirMax M series, why nothing else?

 

https://community.ubnt.com/t5/airMAX-General-Discussion/Rocket-GPS-and-Airsync-FAQ/td-p/115083

 

The SIR requirements for each MCS is given below:

MCS 15/7: 32 dB
MCS 14/6: 29 dB
MCS 13/5: 25 dB
MCS 12/4: 22 dB
MCS 11/3: 18 dB
MCS 10/2: 14 dB
MCS 9/1: 12 dB
MCS 8/0: 7 dB

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Hi @FreenetAntennas 

Thank you for your suggestion, I will talk with documentation and try to update the AF5X datasheet soon.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

It would be nice if one day, the AF5X will automatically set the TX power (up to a user set limit) to achieve the maximum possible modulation for any given link.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


Ron wrote:

It would be nice if one day, the AF5X will automatically set the TX power (up to a user set limit) to achieve the maximum possible modulation for any given link.


I wish that was an FCC requirement for all unlicensed bands.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


mhammett wrote:

Ron wrote:

It would be nice if one day, the AF5X will automatically set the TX power (up to a user set limit) to achieve the maximum possible modulation for any given link.


I wish that was an FCC requirement for all unlicensed bands.


In my opinion this would be silly.   The best way to deploy multiple devices is to turn the power up just enough to achieve the desired performance, plus a little fade margin.  Automatically cranking everything to the max allowed seems counterproductive and would quickly destroy our airwaves.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


ClaudeSS wrote:

mhammett wrote:

Ron wrote:

It would be nice if one day, the AF5X will automatically set the TX power (up to a user set limit) to achieve the maximum possible modulation for any given link.


I wish that was an FCC requirement for all unlicensed bands.


In my opinion this would be silly.   The best way to deploy multiple devices is to turn the power up just enough to achieve the desired performance, plus a little fade margin.  Automatically cranking everything to the max allowed seems counterproductive and would quickly destroy our airwaves.


I'm not sure we're reading the same words. Well, that or you just like to argue.

 

Ron advocated ATPC. I agreed. Maximum TX power to sustain a given modulation. That also seems to be what you're in favor of, but at the same time...  not.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Hi,

 

Actually, the plan is to set a receive power target and adjust the power accordingly. Adjusting to meet a specific modulation rate (rather than a receive power) would have the undesired effect of causing units to crank up their power if interference was present...this could cause more interference and thus create a vicious cycle. 

 

Chuck

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

An option for either system?

 

Send an SNMP trap when this occurs?

 

Use large enough antennas and you are less likely to receive or cause interference.  ;-)

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


UBNT-Chuck wrote:

Hi,

 

Actually, the plan is to set a receive power target and adjust the power accordingly. Adjusting to meet a specific modulation rate (rather than a receive power) would have the undesired effect of causing units to crank up their power if interference was present...this could cause more interference and thus create a vicious cycle. 

 

Chuck


However, if a higher modulation rate can be achieved by cranking up the power than while the interference caused on other links will increase (they will hear more noise), the air time in use by this link will decrease. The time weighted average interference may actually decrease overall.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Hi,

 

We are always transmitting (even if there is no user data) to monitor the link and update the capacity graph; this is not WiFi. The entire reason for ATPC is to REDUCE interference by allowing for lower transmit levels Man Happy

 

Chuck

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


UBNT-Chuck wrote:

Hi,

 

We are always transmitting (even if there is no user data) to monitor the link and update the capacity graph; this is not WiFi. The entire reason for ATPC is to REDUCE interference by allowing for lower transmit levels Man Happy

 

Chuck


So then any dB less at any point is an advantage? I'm missing the downside here...

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

40 MHz

5155-5204

5165-5219

5180-5228

5189-5250

37

39

44

49

 

I'm not sure that I'm reading this correctly, the overlapping ranges adds to the confusion.  Does this mean at 5229, the limit is 49dBm?  Because is a 40Mhz wide at 5229 my connection says its limited at 38dBm.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation


russman wrote:

40 MHz

5155-5204

5165-5219

5180-5228

5189-5250

37

39

44

49

 

I'm not sure that I'm reading this correctly, the overlapping ranges adds to the confusion.  Does this mean at 5229, the limit is 49dBm?  Because is a 40Mhz wide at 5229 my connection says its limited at 38dBm.


The heading that was under was EURP limits in the united states.

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

Any news about "I still want to see the required SNR " ?

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Re: AF5X useful info - power/sensitivity to achieve certain modulation

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