Narrowband Internet of Things (NB-IoT) is a cellular IoT communication technology standardized by 3rd Generation Partnership Project for supporting massive machine type communication and its deployment can be realized by a simple firmware upgrade on existing LTE networks. The NB-IoT requirements in terms of energy efficiency, achievable rates, latency, extended coverage, make the resource allocation, in a limited bandwidth, even a more challenging problem w.r.t. to legacy LTE. The allocation, done with sub-carrier granularity in NB-IoT, should maintain adequate performance for the devices while keeping the power consumption as low as possible. Nevertheless, the optimal solution of the resource allocation problem is typically unfeasible since non-convex, NP-hard and combinatorial because of the use of binary variables. In this paper, after the formulation of the optimization problem, we study the resource allocation approach for NB-IoT networks aiming to analyze the trade-off between rate and latency. The proposed sub-optimal algorithm allocates radio resource (i.e. subcarriers) and transmission power to the NB-IoT devices for the uplink transmission and the performance is compared in terms of latency, rate, and power. By comparing the proposed allocation to a conventional Round Robin (RR) and to a brute-force approach, we can observe the advantages of the formulated allocation problem and the limited loss of the sub-optimal solution. The proposed algorithm outperforms the RR by a factor 2 in terms of spectral efficiency and, moreover, the study includes techniques that reduce the dropped packets from 29% to 1.6%.
The fifth-generation (5G) and beyond 5G (B5G) wireless networks introduced massive machine-type communications (mMTC) to cope with the growing demand of massive Internet of things (IoT) applications. However, the heterogeneous characteristics of massive IoT and diverse quality of service (QoS) requirements may lead to severe interference that could degrade the expected QoS of the cellular ecosystem.Therefore, this paper studies the impact of interference caused by mMTC connections. We theoretically model the inter-cell interference (ICI) minimization problem for the existing orthogonal multiple access (OMA) technique and propose its corresponding solution. Furthermore, we jointly solve the ICI and the co-channel interference minimization problem for the IoT users when the non-orthogonal multiple access (NOMA) technique is used. For the proposed OMA and NOMA schemes, we design a cooperative scheduler to reduce the impact of such interference. The results show that our proposed schemes provide up to 58%, 75%, and 100% more improvements in terms of user's data rates, energy consumption, and connection density, respectively
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