In conventional Slotted-Aloha channels, simultaneous transmission by two or more users results in a collision, the unsuccessful packets have to be retransmitted according to retransmission probability, it is known that this collision causes the Slotted-Aloha to be unstable and this instability is stabilzed by using adaptive control of retransmission probability. In a mobile radio environment, the power level difference between the received packets may arise due to Rayleigh fading(multipath propagation), shadowing(by buildings and hills) and the near/far effect, therefore the packet arriving with the highest power has a good chance of being detected accurately, this is called capture effect. By using both capture effect and adaptive control of retansmission probability, we can improve the throughput and achieve the stability of Slotted-Aloha.
