A truncated-HARQ based random access protocol for wireless slotted ALOHA MIMO systems

Packet collision resolution is proved to be a promising approach to improve the performance of slotted ALOHA protocol with TDMA technique. In the present paper, we propose a random access protocol that utilizes an efficient Spatial Successive Interference Canceller (SSIC) to separate collided packets for users that share the same time slot and that utilizes the benefits of retransmitted packets combining. We consider a truncated Hybrid automatic repeat-request (HARQ) scheme where the number of retransmissions is limited. Moreover, for the SSIC, we give a solution for the problem of very close powers of collided packets by using a simple linear processing for its initialization. We evaluate the throughput of the system over Rayleigh fading channel using the proposed protocol. The simulation results show that we obtain an efficient random access method with high throughput for wireless transmission.