There is no way, as far as I know, to use multiple dongles for one connection. You could use two dongles to connect your PC to two different Wifi signals (like 1 on your WiFi and the other on your neithbor's WiFi), but that's not what you asked.
Therefore, you will have to use the most performant adapter you own.
In general, your USB WiFi dongle will have better results. You can monitor your wireless connection with the command :
First, use this command while your are connected with the built-in chips.
Then use it again with your USB adapter connected, when the built-in one is not used.
Choose the most performant one.
How-to : read the
iwlist scanning results
- Go to the wlan section (wlan0 by default), that means "WiFi".
- Cell 01 is the first signal recieved, Cell 02 is the second one, etc.
- To have a "human-readable" name, check the ESSID line, for each Cell. That is the name your WiFi has, the same name you must clic on to connect with Ubuntu.
- Once you have identified your signal section, check the Quality line, and mainly the Signal level line, expressed in Decibels (dBm)
-> This is what we were looking for ! The signal strength in dBm represents the quality of your reception, thus the quality of your WiFi Adapter.
In dBm, the higher is better. Note that the dBm number is a NEGATIVE number, so
-68 is higher than
-91 (so : -68 dBm is a better quality than -91 dBm).
Another thing : You will notice the Frequency line in the
iwlist scanning results. If you leave near other people who also have a Wifi connection (your neightbors for example, or other people living in the same building, ...) and use the same Frequency as you do, you may want to change the frequency you are using.
Why ? Because using the same frequency as others can mess up your transmission, other WiFi acting like parasites to you, and you acting like a parasite to other's signal.
You can change easily the frequency of your WiFi by choosing another Channel or another Frequency in your Internet Box options (not sure of the english name for Internet Box... I mean the electronical device where your WiFi signal come from, the thing that's plugged into the wall in your house).