Default [Q] How can I upgrade my modem and what modem do I need to use?

My device is running Cyanogenmod 10.2 but over the last few months I can't see any signal bars and my 3G performance is horrible. I've been digging around on XDA and found that this can be resolved by flashing a new firmware but I don't know how and which firmware to use. My baseband is currently XXALIE.

I've made a backup of my EFS and my modem like this:

dd if=/dev/block/mmcblk0p3 of=EFS.img bs=4096
dd if=/dev/block/mmcblk0p10 of=XXALIE.img bs=4096
I now have a backup as everyone recommends. Could anyone guide me as to what to do next? I found this thread containing a list of modems: I also found another thread that explains about the signal-bar issue but I can't understand it:

I would be really grateful if someone could help me out. Thank you.