You can solo it. I did. Stay at the back on the spawn. Sometimes a fallen will come up to you (3 for me) so have your shotgun ready. Sniper and rockets. Took a shit load of rockets and and I constantly ran out of amo. Watch the snipers and you will be ok. Go as a defender Titan as it will help. If you run out of amo use all your amo and you will get replenished on all weapons. Takes about a minute though.