That device is very old and has limited resources (4MB flash, 32MB RAM). You will have difficulty running any recent version of OpenWrt. See this warning.
Upgrading to OpenWrt may or may not change the speed of your service -- have you tried connecting your AK40v directly to a computer to see if there is a difference in performance when connected directly vs via the MR3020? As a cellular device, it is subject to the quality of the cellular service in your location, so you speeds may vary just based on signal quality.
I have changed cellular service provider, and I have these results: directly 21Mb/s (D) 20 (U), with router 9 (D) 14 (U).
If I install OpenWRT v. 17 (lede-17.01.7-ar71xx-generic-tl-mr3020-v1-squashfs-sysupgrade.bin), will the dongle Alcatel AK40v function without to install others packages?
I don't know LEDE 17.01.7 will be any faster than the stock firmware. However, you may run into a space issue -- the 4MB flash may not fit the firmware + drivers for your AK40v (I'm not sure what is needed and how much space it will take up). You can certainly try it, but if you run out of space, it would require an extroot process to give you more space, and that would require a USB hub to facilitate connecting both a USB flash drive and your AK40v.
A better solution in all respects would be to consider purchasing a more recent, more powerful, and aster device. The successor to the MR3020 is the TL-WR902AC. It is 8/64 and supports 802.11ac. There are also other devices such as several from GL-Inet that are similar and have even more flash and RAM.