RE
Grenades Launcher wireless bonus:This simply mean that there is a manual button on your grenade launcher that you can press for a simple action to detonate mini-grenades that have a wireless trigger.
So if you don't have DNI (which you can use to wireless detonate your mini grenade for a free action) or if someone bricked your data jack or if you ran out of free actions this action phase you can use a simple action to detonate the grenade by pressing the button on your grenade launcher.
This require the grenade launcher to be wireless ON (of course, since the button will not transmit the command to your wireless grenade if the grenade launcher have wireless OFF).
There is often a quite logical explanation to most wireless bonuses...
How do you explain to your players, that the impact triggered grenade they just shot is scattering back in their direction?
"Scatter" does not have to be the same thing as "bouncing".
They simply hit the ceiling, wall, floor, a piece of furniture or a tree branch or whatever between the target and themselves and the grenade detonated.
Motion sensor grenades use standard ranged rules (target get to use reaction+intuition to avoid it). As long as they get one net hit or more the grenade will hit their target (and not scatter at all).
What exactly does airburst link do? Does it only reduce scatter?
The purpose of the Airburst link is to detonate wireless grenades for you.
Both your grenade launcher and your mini grenades need to have Wireless ON.
(I
think your grenade launcher also need to be a smartgun...)
This save you a free action (if you have DNI linked wireless to your grenade) or a simple action (if you use grenade launcher linked wireless to your grenade). This is also the only way you can practically use a semi-automatic burst to fire
and detonate 3 wireless triggered mini-grenades in one action phase...
(air-burst = detonating the explosive mid-air close to your target - opposed to ground-burst which is often a timed grenade that bounce and roll and detonate while laying on the floor after a set period of time. Air-burst is a technology that exist real life).
http://en.wikipedia.org/wiki/Air_burst