connectivity procedure, and removing the need for pairing and fine synchronization, grant-free radio access has attracted lots of interests in recent years for providing low-power ultra-durable IoT connectivity, especially when more than 10 years lifetime is required. SigFox and LoRa are two dominant grant-free radio access solutions over the public ISM-band, which is used for industrial, scientific, and medical purposes [@mag_all]. While energy consumptions of LoRa and SigFox solutions are extremely low, and their provided link budget is enough to penetrate to most indoor areas, e.g. LoRa signal can be decoded when it is 20 dB less than the noise level, reliability of their communications in coexistence scenarios is questionable [@int2; @mey]. [@int2] presents experimental measurements in such coexistence scenarios, where multiple IoT technologies are sharing a set of radio resources, and confirms significant impact of interference on IoT communications. Regarding the growing interest in grant-free radio access for IoT communications in public and proprietary cellular networks [@gf31; @mag_all], it is required to investigate the reliability, battery lifetime, and scalability of such networks in serving multi-type IoT devices.

Literature Study
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Non-orthogonal radio access has attracted lots of attentions in recent years as a complementary radio access scheme for future 