1) In a wireless network, Node A thinks by mistake that it cannot send a packet to another receiver C, due to a noisy neighbor B, where C and B are non-overlapping broadcast ranges. What is this problem called?

2)In a wireless network, node A thinks it can send to a receiver B (because channel is empty upon listening) and the messages collides at B, due to collision with another node D's transmission, and nodes A and D are non-overlapping ranges. What is this problem called?