Joint resource allocation, 3D placement, and user association in ABS‐supported IoT networks considering adaptive modulation technique

Abstract

AbstractIn this paper, a novel method for joint resource allocation, three‐dimensional placement, and user association as a predominant problem in the internet of things (IoTs) networks is proposed. We consider two kinds of channel models for the links between users and aerial base stations (ABSs), namely (a) line of sight (LoS) model and (b) generalized model. In the LoS case, all the ABSs should establish LoS communications path toward IoT users. In the generalized case, the ABSs channels toward the IoT users could be LoS or nonline of sight. We propose four different scenarios, namely interference‐free (IF)‐LoS, IF‐Generalized, interference‐included (II)‐LoS, and II‐Generalized. The IF‐LoS and IF‐Generalized cases consider subcarrier and modulation order as the resources while the II‐LoS and II‐Generalized cases consider transmit power, subcarrier, and modulation order as the resources. Our objective function is minimizing the overall transmit power of the IoT users while satisfying some quality of service constraints in the uplink. To solve the resulting nonconvex optimization problem, we convert the main problem with high complexity into the subproblems with low complexities. We compare the performance of our joint proposed scenario with other joint and disjoint cases for the IF‐LoS, IF‐Generalized, II‐LoS, and II‐Generalized cases. Moreover, we evaluate the performance of the proposed schemes for different numbers of ABSs, environment types, target areas, and numbers of IoT users.