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Minimum level and SNR for IEEE 802.11 a/b/g/n

 
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HEKnet
Advisor

Minimum level and SNR for IEEE 802.11 a/b/g/n

Hi,

this is actually not specifically related to HP networking products, but I run a MSM 765zl with E-MSM 430 and I did not find the information in any other place, so here it is.

 

Does anybody know the minimum requirements for level and SNR to ensure an undisturbed wifi connection?

 

For 802.11g at 54 MBit/s I found these values on some Cisco page.

 

Minimum rx level: -67 dB

Minimum SNR: 25 dB

Minimum margin between two cells using the same channel: 19 dB

 

Does anybody know the minimum requirements for the other standards a/b/n? What is about the 5 GHz band?

 

I tried a look into the official IEEE standards but without luck.

1 REPLY 1
Highlighted
Manfred M.
Advisor

Re: Minimum level and SNR for IEEE 802.11 a/b/g/n

I think that there is no exact value. There is no 100% functional guarantee for wireless communication. It's always best effort.

 

Receiver sensitivity or RF sensitivity is one of the key specifications of any radio receiver whether it is used for WLAN, cellular telecommunications broadcast or any other form of wireless communications.

 

There are big differences in the sensitivity among the products.

 

The ability of the radio receiver to pick up the required level of radio signals will enable it to operate more effectively within its application.

 

The two main requirements of any radio receiver are that it should be able to separate one station from another, i.e. selectivity, and signals should be amplified so that they can be brought to a sufficient level to be heard. As a result receiver designers battle with many elements to make sure that these requirements are fulfilled.

 

The current generation of 802.11b/g devices can maintain a wireless connection for a signal stronger than -85 dBm. However, a good connection will require at least -75dBm.

With 802.11n it's very similar.

 

As a rule of thumb I use -70dBm as the today's limit for 54Mbit.

In WLAN Site Surveys I look at the -67dBm Margin - especially if the customer is planning VoWLAN.

Also the overlapping of the cells is important - data only: 5-10% VoWLAN 15-20%. No matter if it's 2,4 or 5GHz

 

And - Yes - SNR (the 25dB Margin is advisable) is important, but it's digital not analog - interference most of the time limits only the data rate...

 

Good luck!