When you're dead, you go into "incapacitated mode".
Ok but is their just a straight DEAD. is incapacitated mode when your knocked down by teh butt of a rifle? and isnt it true in this mode that an enemy could finish you off? in that case do you instantly respawn?
I'll explain it from 0. It's all in the compendium though...
Incapacitated: You lost all your health. You can wait for a medic or join the next respawn wave, which is determined by a timer. When you join the respawn wave you're DEATH. When the respawn timer hits zero, everyone who was death will respawn. (Respawn time can vary between +- 1-30. You can time your respawn by waiting for a medic for 29 seconds and join the next wave in the last second.)
Death: By joining a respawn wave. Probably by dieing from receiving excessive damage by an explosive (Like in previous SD games. It's not confirmed). When melee'd after knock down. When melee'd after incapacitated. When receiving a lot of fire when incapacitated.
Knock down: By getting hit by gunnbut, tackle or splash damage.