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A broadband waveguide-to-differential-line transition with a triple stacked patch is proposed for use in 300 GHz band. This transition consists of differential signal lines inserted into the waveguide region from both broad walls of the waveguide. A triple circular stacked patch element was used for broadband transmission from the waveguide to the planar differential line formed in a multi-layer substrate. Concurrently, the optimized arrangement of via holes can prevent electric field leakage efficiently and improve the transmission characteristic in a high-frequency band. The geometry of the transition was optimized through electromagnetic simulations using the finite element method. Measurements and simulations were implemented to evaluate the performance of the transition. The measured result of the transition shows the bandwidth of the $S_{11}$ below −10 dB was over 100 GHz.

Nanomachines are submicrometer-scale devices led by nanotechnology that can perform simple sensing, local actuation, limited data processing, storage, and communication tasks in the terahertz (THz) band, that is, from $\mathrm {0.1~}$ - $\mathrm {10~ \text {T} \text {Hz} }$ . Electromagnetic nanocommunication among nanomachines results in a nanonetwork which could breakthrough promising applications in multiple domains such as software-defined metamaterials, in-body communication, and on-chip communication. This study adopts a modulation scheme for nanomachine communication based on multilevel pulse position modulation (ML-PPM). The multilevel scheme uses several orthogonal codes and is combined with PPM to generate the final transmit signal consisting of several multilevels. In this paper, we propose a more advanced scheme called level trimming to further boost the data rates of the ML-PPM scheme. Employing level-trimming, we transmit a fewer number of levels than required in ML-PPM, which will result in an spectral efficiency gain at the nanoreceiver. The simulation results reveal that the link capacity of the proposed scheme can be increased more than twofold using the level-trimming approach while the error rate performance remains better than the conventional ML-PPM. For instance, ML-PPM with level trimming achieves a data rate of approximately 4.5 terabits per second (Tbps) when trimming the levels from seven to one compared to ML-PPM that achieves around $\mathrm {1~Tbps}$ under the same network conditions. At the same time, a $\mathrm {2~dB}$ gain in BER performance is achieved with level trimming. Moreover, the computational complexity of nanotransceivers is reduced with the transmission of fewer levels. Furthermore, although level-trimming causes artificial errors, it improves the decoding performance by reducing the number of levels. We believe that the potential impact of this study will open doors for further investigations on various possible modulation formats for THz nanocommunication.

The recent demand for connections to a huge number of users with very high data rates have motivated research communities to investigate communications into the higher frequency bands, such as millimeter waves and TeraHertz (THz) bands. Moreover, Subcarrier Index Modulation (SIM) has recently received a significant research efforts analyzing its different performance aspects. In this paper, we propose a SIM system operating over the THz band and analyze its performance considering mobile users and different resource allocation schemes. Specifically, Random WayPoint (RWP) mobility model is considered for users’ mobility with different numbers of mobility dimensions, and three different spectrum resource allocation schemes, namely, fixed-order allocation, random allocation and distance-aware allocation are considered. Our analysis includes deriving mathematical expressions of both the average Bit Error Rate (BER) and the average Outage Probability (OP) for the three resource allocation schemes. Simulation results analyze different performance metrics like the BER and the OP and are shown to validate the accuracy of the derived expressions.

Nanotechnology is a multidisciplinary field that will make our life simpler and safer and mitigate our impact on the surrounding environment. With the recent advancements and transformations in the available networking and communications paradigms, embedding Wireless Nano Sensor Networks (WNSN) with various objects, sensors, and devices would add a new network paradigm. This paradigm is known as the Internet of Nano Things (IoNT). Seamless interconnectivity among nanonetworks with the available communication networks and the Internet requires developing new network architectures and new communication paradigms while addressing the various technical challenges. Routing protocol is one of the most essential requirements in WNSN and IoNT due to the different nanoscale constraints. This routing protocol must accommodate nanoscale communication's characteristics while guaranteeing the data and information transmission. This study aims to give insight into WNSN and IoNT paradigms and present a comprehensive review of a large number of existing routing protocols adapted to nano communication's characteristics and features.

6G and beyond will fulfill the requirements of a fully connected world and provide ubiquitous wireless connectivity for all. Transformative solutions are expected to drive the surge for accommodating a rapidly growing number of intelligent devices and services. Major technological breakthroughs to achieve connectivity goals within 6G include: (i) a network operating at the THz band with much wider spectrum resources, (ii) intelligent communication environments that enable a wireless propagation environment with active signal transmission and reception, (iii) pervasive artificial intelligence, (iv) large-scale network automation, (v) an all-spectrum reconfigurable front-end for dynamic spectrum access, (vi) ambient backscatter communications for energy savings, (vii) the Internet of Space Things enabled by CubeSats and UAVs, and (viii) cell-free massive MIMO communication networks. In this roadmap paper, use cases for these enabling techniques as well as recent advancements on related topics are highlighted, and open problems with possible solutions are discussed, followed by a development timeline outlining the worldwide efforts in the realization of 6G. Going beyond 6G, promising early-stage technologies such as the Internet of NanoThings, the Internet of BioNanoThings, and quantum communications, which are expected to have a far-reaching impact on wireless communications, have also been discussed at length in this paper.

Current developments in nanotechnology make electromagnetic communication possible at the nanoscale for applications involving body sensor networks (BSNs). This specialized branch of wireless sensor networks, drawing attention from diverse fields, such as engineering, medicine, biology, physics, and computer science, has emerged as an important research area contributing to medical treatment, social welfare, and sports. The concept is based on the interaction of integrated nanoscale machines by means of wireless communications. One key hurdle for advancing nanocommunications is the lack of an apposite networking protocol to address the upcoming needs of the nanonetworks. Recently, some key challenges have been identified, such as nanonodes with extreme energy constraints, limited computational capabilities, terahertz frequency bands with limited transmission range, and so on, in designing protocols for wireless nanosensor networks. This work proposes an improved performance scheme of nanocommunication over terahertz bands for wireless BSNs making it suitable for smart e-health applications. The scheme contains - a new energy-efficient forwarding routine for electromagnetic communication in wireless nanonetworks consisting of hybrid clusters with centralized scheduling; a model designed for channel behavior taking into account the aggregated impact of molecular absorption, spreading loss, and shadowing; and an energy model for energy harvesting and consumption. The outage probability is derived for both single and multilinks and extended to determine the outage capacity. The outage probability for a multilink is derived using a cooperative fusion technique at a predefined fusion node. Simulated using a nano-sim simulator, performance of the proposed model has been evaluated for energy efficiency, outage capacity, and outage probability. The results demonstrate the efficiency of the proposed scheme through maximized energy utilization in both single and multihop communications; multisensor fusion at the fusion node enhances the link quality of the transmission.

In this paper, a new 3-D electromagnetic (EM) simulation approach for heterojunction bipolar transistor (HBT) parameter extraction in terahertz band is presented. We introduce an inter-electrode impedance equivalent-circuit model with the concept of dispersive parameters and a more rigorous 3-D EM simulation parameter extraction method to avoid serious discrepancies between the simulated EM field distribution and the real EM field distribution of the device. Terahertz parasitic effects, including the EM field discretization and multi-finger device field sharing, are observed. Compared with the previous 3-D EM simulation-assisted model, the new model in this paper demonstrates better results for multi-finger indium phosphide HBTs.

This paper presents a study on physical layer authentication problem for in vivo nano networks at terahertz (THz) frequencies. A system model based on envisioned nano network for in vivo body-centric nano communication is considered and distance-dependent pathloss based authentication is performed. Experimental data collected from THz time-domain spectroscopy setup shows that pathloss can indeed be used as a device fingerprint. Furthermore, simulation results clearly show that given a maximum tolerable false alarm rate, detection rate up to any desired level can be achieved within the feasible region of the proposed method. It is anticipated that this paper will pave a new paradigm for secured, authenticated nano network for future applications, e.g., drug delivery and Internet of nano-things-based intelligent office.

Massive multi-core processing has recently attracted significant attention from the research community as one of the feasible solutions to satisfy constantly growing performance demands. However, this evolution path is nowadays hampered by the complexity and limited scalability of bus-oriented intra-chip communications infrastructure. The latest advantages of terahertz (THz) band wireless communications providing extraordinary capacity at the air interface offer a promising alternative to conventional wired solutions for intra-chip communications. Still, to invest resources in this field manufacturers need a clear vision of what are the performance and scalability gains of wireless intra-chip communications. Using the comprehensive hybrid methodology combining THz ray-tracing, direct CPU traffic measurements, and cycle-accurate CPU simulations, we perform the scalability study of x86 CPU design that is backward compatible with the current x86 architecture. We show that preserving the current cache coherence protocols mapped into the star wireless communications topology that allows for tight centralized medium access control a few hundreds of active cores can be efficiently supported without any notable changes in the x86 CPU logic. This important outcome allows for incremental development, where THz-assisted x86 CPU with a few dozens of cores can serve as an intermediate solution, while the truly massive multi-core system with broadcast-enabled medium access and enhanced cache coherence protocols can be an ultimate goal.