medium access

medium access control

sum rate

network coding

rayleigh fading

successive interference cancellation

multiple access noma

base station

slotted aloha

IEEE Communications Letters

In this letter, non-orthogonal multiple access based coded slotted ALOHA (NOMA-CSA) for machine-type communications (MTC) is proposed, in which encoded segments are transmitted with discrete power levels. Most collided segments can be successfully decoded by using the successive interference cancellation (SIC) and maximum-a-posteriori (MAP) erasure decoding. To further improve performance, the code degree distribution and the power distribution for the different number of power levels are jointly optimized, which leads to considerable performance improvement. Numerical results verify our analysis and show that the NOMA-CSA greatly outperforms conventional schemes in terms of throughput and packet loss rate (PLR).

NOMA-Based Coded Slotted ALOHA for Machine-Type Communications