Versionen fra 1. sep 2019, 06:29

WiFi tips

Alt radio er lidt voodoo.

Godt modtager signal skal ligge mellem -40 dBm til -65 dBm, ca. -45 dBm er bedst.

Noise floor / baggrundsstøj er normalt -90 dBm til -100 dBm, der skal signalet helst være ca. 30-32 dBm over, for at være godt. Og så gerne 15 dBm i "buffer" til signal tab. = 45 dBm.

Husk der er støj i begge ender, både ved AP og klienten. For at få god hastighed er signal-to-noise ratio (SNR) er mere vigtigt end et stærkt signal.

I stedet for at AP sender et stærkt signal (TX power), er det bedre at sætte sende styrken lidt ned, så alle klienter også kan svare tilbage. Eller sætte en god antenne op, da den forstærker signalet begge veje. Især i high density miljøer. Altså flere, men små wireless celler.

Lad være med at bruge de første kanaler i 5GHz, da mange bruger dem som standard. Vær opmærksom på DFS/radar.

Bredere kanaler, 40MHz osv, sender dårligere (mindre rækkevidde) da er kun er den samme "energi" til rådighed. Men kan give bedre båndbreade

Hidden node: The probability of a collision also increases whenever the distance between stations is so great that they cannot hear each other. This can also occur if obstacles exist between stations. This is known as the hidden node problem. For example, if Station A is close to the AP but far from Station B who is talking, Station A will wrongfully assume that the wireless channel is available and transmit, causing problems (collisions) at the listening AP.

http://mcsindex.com/

https://www.ui.com/downloads/guides/training/courses/UEWA_Training_Guide_V2.1.pdf

UniFi tips

Reset:

• SSH into the AP and issue 'syswrapper.sh restore-default'
• You can use the UniFi discovery tool (installed with the UniFi controller) to reset the UniFi AP to defaults.

Once the unit is reset it will come into default state, please try setting the inform URL by following these steps:

• SSH into the AP and issue ‘syswrapper.sh restore-default’ to get back to factory settings.
• SSH into the AP and type: mca-cli
• Next type: set-inform http://ip-of-controller:8080/inform

ubnt / ubnt

192.168.1.20 is the by default UniFi IP.

• To reset the UniFi APs, power them on, and allow them to fully boot.
• After they've booted, press and hold the small reset button (located on the back of the device) for 25+ seconds.
• This should reset the UniFi APs and put them back into a discoverable state again.
• If hard reset doesn't work then you try TFTP recovery: To TFTP recover firmware, please follow the instructions found here: http://community.ubnt.com/t5/UniFi-Troubleshooting/UniFi-TFTP-soft-recovery/ta-p/607605