Polarized MIMO Slotted ALOHA Random Access Scheme in Satellite Network

The massive number of the machine type communication terminals accessing the satellite network brings a new challenge for the random access (RA) system. To meet the challenge, by using the polarization transmission structure in the satellite uplink, we propose a new RA scheme dubbed polarized multiple input multiple output slotted ALOHA (PMSA). In PMSA, in one slot, one packet and two overlapped packets can be decoded successfully with the polarized MIMO detection algorithms, and some of three overlapped packets may be decoded successfully in consideration of the capture effect at the satellite node. For the new features of the proposed scheme in physical layer, the protocol of medium access control (MAC) is modified based on the slotted ALOHA (SA). Simulation results show that the normalized throughput of the PMSA can reach 0.84 and is consistent with the theoretical throughput. Moreover, it is also shown that the throughput of PMSA is about 2.3 times as large as that of the SA and 1.5 times as large as that of the contention resolution diversity slotted ALOHA (CRDSA), without the need for additional transmitted power and time slots to transmit the replicas of the packets. The received packets in the proposed PMSA are processed slot by slot, not as that processed frame by frame in the CRDSA with a large additional frame delay.