A D2D-Based Solution for MTC Connectivity Problem in NOMA-Based Cellular IoT Networks: Dynamic User Grouping and Resourc
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A D2D-Based Solution for MTC Connectivity Problem in NOMA-Based Cellular IoT Networks: Dynamic User Grouping and Resource Allocation Mahdi Kazeminia1 · Mehri Mehrjoo1 · Stefano Tomasin2
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In a cellular network (CN), cellular users (CUs) located nearby machine type communications (MTC) devices (MTC-Ds) may act as uplink gateways to relay data to the base station (BS). We consider non-orthogonal multiple access (NOMA) and successive interference cancellation (SIC) at the receiver to increase the number of connected devices and the spectrum efficiency. Both underlay and overlay spectrum access modes (SAMs) are considered. We introduce a dynamic user grouping (UG) concept as a practical constraint for SIC, in order to decrease the receiver complexity. Moreover, SIC constraints are introduced based on a minimum signal-to-noise-plus-interference ratio (SINR) at the receiver. We formulate a joint dynamic UG, power allocation, and resource block (RB) assignment problem, aiming at maximizing the total sum-rate of both CUs and MTC-Ds. We transform the obtained non-convex mixed-integer programming problem into a convex problem by using a quadratic fractional programming (FP). A heuristic method is also proposed to reduce complexity. Simulation results demonstrate that the proposed solution outperforms the conventional CN (C-CN) method and the results of the proposed optimization methods are close to optimal solution obtained by the exhaustive search (ES) algorithm in terms of total average sum-rate and network connectivity, while requiring less transmit power. The heuristic method decrease the computational complexity of the FP method at the expense of a small reduction in spectrum efficiency. Keywords Machine type communication · Device to device communication · Nonorthogonal multiple access · Successive interference cancellation · User grouping · Resource allocation
1 Introduction Machine type communications (MTC) are the supporting infrastructure of the Internet of Things (IoT) with applications such as smart grids, environmental monitoring, and intelligent transportation systems. In order to obtain reliable
Mehri Mehrjoo
[email protected] Mahdi Kazeminia [email protected] Stefano Tomasin [email protected] 1
University of Sistan and Baluchestan, Zahedan, Iran
2
University of Padova, Padova, Italy
and secure communications, cellular networks (CNs) can be deployed to implement MTC. However, provisioning for massive connectivity of devices is a major challenge of IoT CNs. A solution to the MTC connectivity problem is device to device (D2D) networks (D2D-Ns), that aggregate and relay MTC traffic through CN into MTC servers [1, 2]. As shown in Fig. 1, an MTC network is a set of D2DNs comprising MTC devices (MTC-Ds) in the proximity of cellular users (CUs), which act as MTC gateways (MTCGs). For the deployment of MTC coexisting with CN, the third generation partnership project (3GPP) has introduced both enhanced MTC (eMTC) [3] and
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