Grant-free transmissions based on successive interference cancellation in IoT

Advancements in the physical layer design are pushing towards a major re-design of multiple access schemes for Next Generation Wireless Communication Systems. Hence, we turn towards random multiple access. We use a general model to investigate the interplay between random multiple access protocols and physical layer functions, specifically Successive Interference Cancellation (SIC). We focus on the sum-rate metric, which has been shown to exhibit two local maxim as a function of the target Signal to Interference plus Noise Ratio (SINR) [1]. The contribution of this paper lies with assessing the sensitivity of the optimal sum-rate to the number of concurrent transmissions, transmission power setting, and imperfect interference cancellation. Furthermore, leveraging the understanding gained on sum-rate optimization, we define a sumrate optimal adaptive algorithm, when the number of contending nodes varies with time.