Cooperative Interference Avoidance Scheduler for Radio Resource Management in NB-IoT Systems

The design changes on the physical (PHY) layer, i.e. the limited system bandwidth of one physical resource block (PRB), single antenna support, lower-order modulations, etc. inhibit the mapping of traditional long term evolution (LTE) radio resource management techniques to narrowband internet of things (NB-IoT) systems. Consequently, possible interference due to massive connectivity may severely degrade the expected system performance. In this regard, we propose an interference avoidance scheduling algorithm for NB-IoT systems. The algorithm entails a cooperative strategy in which the base stations share their respective scheduling tables which are then used to compute the interference for future transmitting user equipment (UEs). The computed interference values are then used as input to individual base station schedulers to perform scheduling. Each base station's scheduler then allocates the radio resources to the UEs with the lowest possible interference. Extensive simulations are carried out to analyze the performance of our proposed algorithm and compare it to the conventional Round-Robin scheduling scheme. The results show that our proposed algorithm provides up to 36 % throughput improvement to the NB-IoT UE as compared to Round-Robin. Similarly, for the same device's locations, the UEs are experiencing relatively better maximum coupling loss (MCL) which results in lower repetition numbers per coverage class.