I have 2 questions about physical layer of wireless lan.
1-) Many WLANs(SSID) use same channel for communication, that means they use same frequency, what prevents the collisions between different wlans but same channel?( I am asking about RF signal collision)
2-) Do rts and cts valid for just one wlan that computer which is generated, belongs to or do rts/cts synchronize all different wlans that use same frequency.
So RTS / CTS is inter-wlan. Not just valid for only one wlan.
So when my computer starts to communicate with my wireless modem, other computers even belongs to different wlan/ssid must wait for my computer to finish communication if they are on the same channel ??
So computers or APs that belongs to different wlans/ssids effect each others if they are on the same channel.
To add to Steve response. The air time fairness for 802.11 is call CSMA-CA. It uses phyiscal and a virtual carrier sense. And this is by frequency. So if your ap is on channel 6 and my ap is on channel 6 and steves ap is on channel 6 and we are all close. We would all have to share the air space.
Always try and keep 20 db difference between aps on the same channel.
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin