Transport Capacity Optimization for Resource Allocation in Tera-IoT Networks

We present a new adaptive resource optimization strategy that jointly allocates the subwindow and transmit power in multidevice terahertz (THz) band Internet of Things (Tera-IoT) networks. Unlike the prior studies focusing mostly on maximizing the sum distance, we incorporate both rate and transmission distance into the objective function of our problem formulation with key features of THz bands, including the spreading and molecular absorption losses. More specifically, as a performance metric of Tera-IoT networks, we adopt the transport capacity (TC), which is defined as the sum of the rate–distance products over all users. This metric has been widely adopted in large-scale ad hoc networks and would also be appropriate for evaluating the performance of various Tera-IoT applications. We then formulate an optimization problem that aims at maximizing the TC. Moreover, motivated by the importance of the transmission distance that is very limited due to the high path loss in THz bands, our optimization problem is extended to the case of allocating the subwindow, transmit power, and transmission distance. We show how to solve our problems via an effective two-stage resource allocation strategy. We demonstrate the superiority of our adaptive solution over benchmark methods via intensive numerical evaluations for various environmental setups of large-scale Tera-IoT networks.

I. Introduction

Terahertz (THz) band (0.1–10 THz [1]) communications have been envisioned as a highly promising technology to overcome the scarcity of spectrum resources in current wireless systems [2], [3]. Promising applications include nanoscale applications, such as ultradense Internet of Nano-Things (IoNT) [4], [5], plant monitoring nanosensor networks [6], and wireless body area networks. The Internet of Things (IoT) is evolving toward holographic communications [7] and immersive virtual reality (VR) [8]–[11] using a very high data rate at THz bands with a short distance. Although the millimeter-wave (mmWave) band can also provide a high data rate, it cannot accommodate multiple users who request high rates simultaneously. Thus, the THz bands have received substantial attention very recently for 6G wireless communications [12]. Despite such huge demands, designing ready-to-use THz communication systems leads to new research challenges that have never been encountered by any existing communication systems operating at lower frequencies (e.g., the mmWave spectrum). This is due to the fact that the THz signals suffer from the inevitable high path loss, which is mainly induced by both the spreading effect during propagation and the absorption effect such as molecular absorption [2], [13].