This isn't that bad when you know what enemies to expect and are prepared for when they enter.
-The best weapon for this is the shotguns as you should have enough ammo with them from walking over the enemies bodies to last the entire time.
-Its always best to keep moving to avoid being shot
-CLARION 85 pointed out you have a grenade so you can use that to throw at an entrance to hopefully get a kill at any point.
The first wave is 3 soldiers with 1 being armored.
The second wave is 4 normal enemies
3rd wave has 2 heavies drop in. you should position yourself in the spot behind where one drops in to kill it quickly. the other heavy will charge over to you from the other side so move over a bit and kill him.
After this things pick up with no real downtime between enemies
A wave of 6 enemies spawn so its best to keep moving to each of their entrance points on a rotation so you're not standing still and killing them.
Now 2 robot will enter followed by 5 more soldiers.
Again, if you keep moving its not bad. Petrie91 says running along the outskirts continuously when its just normal enemies allows you to reload and regain armor without being shot.
And if you fail it doesn't take long to restart so its easy to learn.
So heres clip of a complete run of it:https://streamable.com/tri2g
And Here is a clip of my 1st time completing it. a very sloppy run where i had only 1 health in the end but it shows getting it done not fully prepared.