Abstract: The random access procedure is one of the MAC-layer's functions that initiates a contention-based set up to grant an uplink transmission. In this paper, the performance of a new random-access procedure is investigated by introducing a modify ed backoff scheme to reduce collision probability. The proposed scheme can thus improve the overall
throughput of the network and the NB-IoTs battery lifetime while prioritizing some QoS parameters such as favoring the NB-IoTs with heavier traffic loads. The probability of collision analysis is subjected to many operating parameters, including the backoff countdown probability, number of the NB-IoTs, queue size, and the contention window size. The system and link-level simulations are conducted to assess the proposed scheme with up to ve thousand NB-IoTs per cell. The simulation results showed that the proposed scheme outperforms the conventional approach.
Key words: backoff, collision, MAC, random access, window size
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