Just a quick post to talk a bit about RSSI, and why it’s NOT the best way to judge your Wireless LAN.
First a bit of history, more than a decade ago I started into Wireless Networking. Back then the only tools we had were the Cisco ‘Breadcrumbs’ RSSI meter built in the Cisco (Aironet) client software.
Back then we thought Coverage was the Holy Grail – how to get the most coverage with the least amount of Access Points. So getting a strong RF signal, as measured by RSSI was everything. Then we found RF Amplifiers – and we made some HUGE RF coverage circles.
Site surveying was running around with AP-on-a-Stick and measuring how far the RF coverage went. That was all. Just RSSI.
Sad to admit, but I did hundreds of these. (I can only sleep at night knowing that everyone did it that way and no one had any better idea back then of what else to do)
But today we know it’s NOT about the RSSI! Sure, you *must* have good signal. But good signal alone won’t give you a great Wireless LAN design. It’s all about the actual throughput of data over the RF medium.
The new Holy Grail in Wi-Fi is getting the network to provide the actual data throughput and specs needed by the client devices. That is all encompassing.
So instead of measuring only for RSSI, we really need to be measuring better the net throughput, under load, of our Wireless Networks.
Sure, an RF amplifier can transmit a strong signal a long ways… but the net result is you have clients that can see the AP, but the AP can’t see the clients. And you now have HUGE contention domains (Collision Domains) where all devices must wait for the others they can see on the same channel to ‘Share’ the RF medium.
Remember – it’s not about RSSI – it’s about consistent, measured, available throughput!
