But I’ve got an ‘Excellent Signal’!!?
Ever so often I find myself troubleshooting some type of wireless related issue, and while wireless issue’s vary from
- Slow performance
- Clients can’t connect
- Poor voice performance
- Or even random disconnects, the list is endless.
However one of the common things I hear during the troubleshooting process is without a doubt along the lines of:
“But it says I have an excellent signal with five bars!”
And…. my favorite question in response to that statement is:
“What is your data rate?” (usually with this same expression)
Signal strength is only a small piece to the puzzle what determining whether or not you have a good quality signal strength. The signal strength indicator itself could even be misleading, just because a client is registering ‘5 bars’ with a good RSSI and SNR does not necessarily mean the AP on the other end of the connection is seeing a similar RSSI & SNR to the WLAN Client. Do I hear a transmit power mismatch, or a highly reflected RF environment?
Nowadays WLAN clients comes in all shapes and sizes (Phones, Tablets, wireless scanners, VoIP handsets) long gone are the days of wireless is just for laptops. With this wide array of hardware clients, you can guarantee each of these devices have a wireless transmitter with different specifications, and while it is impossible to take into account every WLAN client, the client audience should be considered when designing a WLAN or deploying AP’s.
Consider the an access point is transmitting at it’s max power rating, you can guarantee the wireless phone or VoIP handset does not have that same power level. It’s like two people trying to communicate with each other that across a football field and only one person has a mega-phone. The other guy without the megaphone will need to probably repeat himself a few times for the other person to understand him (Think of that as Data Retries).
One of the better ways to identify a proper Wireless connection would be to verify the the data rate, and see review the data rate statistics. Many of the different WLAN Client software have this functionality, telling us what percentage of the data was transmitted/received at a specific data rate. Now shifting data rates is common in a WLAN, but seeing 90% of data operating at the 1, 2, or 5.5 Mbps data rate is just poor performance.
A while back I posted about Understanding a wireless connection, and I wanted to dive a bit deeper and expand on the concept (albeit years later, but hey better late then never right?)