iwconfig 中 Link Quality and Signal Level 区别

朱雀 2022-05-30 09:29 389阅读 0赞

• Signal quality is defined very briefly in the 802.11 standard. Common  
definitions have  
arisen, but they are usually incorrect. The correct definition hinges on the  
term, “PN code correlation strength,” which is a measure of the match  
(correlation) between the incoming DSSS signal and an ideal DSSS signal.

• Signal to noise ratio is a general term that is used in a novel way by  
802.11  
administrators. Most usages of the term refer to the strength of the signal  
relative to thermal noise within a circuit , but many professionals, use the  
term to refer to the strength of the signal at the receive antenna  
relative to the  
ambient, non-802.11 RF power that is present at the bandwidth occupy by  
the signal. According to the standard communications systems terminology,  
SNR is defined as the ratio of received signal power to the power of the  
additive Gaussian noise that appears at the output of the receiver. While  
thesedefinitions are not wrong, they may lead to confusion when 802.11  
professionals communicate among themselves.

• Receive sensitivity refers to the weakest power level the card’s internal  
thermal noise will allow it to receive. It is unrelated to the ambient, non-  
802.11 RF energy in the environment. \[CHIV-4\].

>  *  Signal level: raw signal level either in dBm or RSSI from the card.
>  *  Link Quality: a subjective measure of how good the link is, including  
>     signal strength, speed the link is operating at vs. capable speed,  
>     packet loss, retries, etc.
> 
> Signal level is just the raw measure of RF energy received by the radio  
> on the card and is one component of link quality.
> 
> Link Quality in correctly-written drivers should be a value in the range  
> \[0, 100\] inclusive representing a percentage between “worst” link and  
> “best” link.
> 
> Link quality in Linux wireless drivers has never been extremely  
> reliable, though this is getting much better as time goes on. The ipw  
> drivers are good examples of how to do link quality correctly.

RCPI（Received Channel Power Indicator） also means RSSI（received signal strength indicator）

参考链接： [Link][]

[Link]: http://lists.shmoo.com/pipermail/hostap/2006-December/014832.html