Help for mavlink communication between UAVs

Hi everybody! I am trying to developing a collision avoidance for multi drones. For this I need the current positions and velocity of each drone. So my idea is to broadcast to other drones their gps_raw_int information to the others drone via mavlink. I’ve created a message in Uorb that take the simple gps infromations and I’ve add the MAVlink system id to the message for identify the drone. And I have set the MAV_BROADCAST param to 1. But drones do not receive data from the others drones. How can I solve this?