Indoor Communication Research Articles

On Power-Line-Based Front-Hauling for IoT Cellular Indoor Communications

On Power-Line-Based Front-Hauling for IoT Cellular Indoor Communications

Integrating Wi-Fi, Li-Fi, and BPL Technologies for a Secure Indoor Communication System.

In today's digital age, there is an increasing demand for integrated wireless and wired technologies; however, there is a difficulty in achieving secure and reliable communications within buildings and facilities. This paper presents a proposal for maintaining the infrastructure while expanding it to implement communication technologies with high transmission and reception speeds and high levels of data confidentiality to enhance the operational efficiency of organizations. Three main technologies have emerged as promising solutions for this purpose: Wi-Fi, Li-Fi, and BPL. Despite the advantages that each technology offers, some drawbacks appear in these technologies that affect data transmission. Wi-Fi, Li-Fi, and BPL can be combined to achieve maximum security and reduce noise and interference via the ESP8266 module. This combination could be an important step toward achieving an integrated and secure indoor communication system. The paper provides a comprehensive overview of the three techniques and how they are applied in practice. In addition, OSE, ABPF, and ASBF filters are used to detect and eliminate interference and attack secure internal networks.

RT-SVM: Channel modeling and analysis for indoor terahertz communication scenarios

Considering the increasing demands for wireless communication networks and information system applications, the wireless sector must meet the pressing requirement for high-speed technological advances. The terahertz (THz) frequency band, spanning 0.3 to 10 THz, is of significant interest in current technological innovations and academic research in telecommunications. The THz frequency band has unique properties, including high time-resolving power (femtosecond) and low absorption. This paper proposes a THz propagation ultra-wideband (UWB) channel model and coding scheme for indoor environments starting from 0.3 THz. First, we investigated the propagation path loss model by considering the effects of transmitter dimensions, molecular absorption, and attenuation as functions of frequency and distance. We developed models for power propagation delay, multiple input multiple output (MIMO) systems and discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) response channels. Using the standard Saleh-Valenzuela model combined with Ray-tracing (RT-SVM), we studied the transmission of THz signals in indoor scenarios. We introduced physical parameters relevant to the THz indoor channel, such as line-of-sight (LoS) path loss, power distributions, temporal and spatial properties, and associations between THz multipath properties. These parameters were integrated with the RT-SVM channel model and applied to THz indoor communication. Numerical simulations demonstrate that the proposed hybrid channel model enhances THz system performance and outperforms traditional statistical and geometric-based stochastic channel models in terms of temporal and spatial dimensions, contributing to frequency loss variations.

(Invited) Development of High-Bandwidth GaN-Based Micro-LEDs for Visible Light Communication

With the expectation of extremely high-capacity requirement of 6G networks, visible light communication (VLC) has abundant frequency resource and excellent performance in 6G integrated communication in space, air, underwater, indoor, and car networks [1]. The micro light emitting diode (micro-LED) is regarded as a reliable light source for high-speed VLC and is capable of illumination while providing communication. Compared to the traditional light source, micro-LED possesses better characteristics such as high bandwidth, low power consumption, long lifetime and high reliability [2-3].In this work, we made improvements in the micro-LED fabrication compared with the common negative doped GaN (common-n) devices we produced by shallow etching before [4]. Micro-LEDs can be manufactured into completely separate pixels for independent control by deep etching. For green micro-LEDs with a wavelength of 510nm, the light output power of deep etching one increased. At the same working current density, the -3dB bandwidth of deep etching micro-LED has an average growth of 50% compared to shallow etching one. Benefit from the promotion of optical power and -3dB bandwidth, micro-LED with independent etching structure have a better performance in VLC system. A record date rate of 6.58Gpbs was achieved by single green micro-LED employing the orthogonal frequency division multiplexing (OFDM) modulation scheme, which proposes a feasible optimization direction for the integration of micro-LED high-speed VLC and lighting. REFERENCES: [1] Chi N, Zhou Y, Wei Y, et al. Visible light communication in 6G: Advances, challenges, and prospects[J]. IEEE Vehicular Technology Magazine, 2020, 15(4): 93-102.[2] James Singh K, Huang Y M, Ahmed T, et al. Micro-LED as a promising candidate for high-speed visible light communication[J]. Applied Sciences, 2020, 10(20): 7384.[3] Lin R, Jin Z, Qiu P, et al. High bandwidth series-biased green micro-LED array toward 6 Gbps visible light communication[J]. Optics Letters, 2022, 47(13): 3343-3346.[4] Zhu S, Qiu P, Shan X, et al. Micro-LED based double-sided emission display and cross-medium communication[J]. IEEE Photonics Journal, 2022, 14(3): 1-5. Figure 1

60-GHz Millimeter-Wave over Visible Light Communications for Downlink Wireless Networks

Background and Objective: In this paper, we address potential solution for downlink wireless communications by integrating visible light communications (VLC) with the broadband radio frequency (RF) networks operating at 60 GHz-millimeter wave (mmWave) band. For this hybrid design, the outdoor 60 GHz-mmWave based RF link is utilized to ensure backhaul connectivity for VLC indoor system, while the VLC exploiting the lighting infrastructure that essentially used LEDs as optical source to provide low-cost and high-speed data access. Methods: The hybrid 60 GHz-mmWave/VLC system is analyzed by using 16-QAM OFDM signal, and its performance is investigated by evaluating the signal to noise ratio (SNR) and the received signal power distributions, for regular placement of LEDs and random location of receivers within the room. The impact of the transmitter-receiver parameters, and their orientations and directivities are also considered. Results: Numerical results show the efficiency of the proposed system, which can retransmit RF signals at 60 GHz-mmWave band using visible optical carriers in the indoor environment. Conclusion: The results suggest that the hybrid 60 GHz-mmWave/VLC system is able to provide reliable wireless data transmission, making it an attractive solution for downlink indoor communications.

E‐ and H‐plane beamwidth‐reconfigurable MIMO antenna

AbstractA novel E‐ and H‐plane beamwidth‐reconfigurable Multiple Input Multiple Output (MIMO) antenna is presented here. The antenna consists of four two‐dimensional directional reconfigurable antenna elements that utilizes Positive‐Intrinsic‐Negative (PIN) diodes to achieve stable beamwidth reconfiguration in both the E‐plane and the H‐plane. Simulated and testing results of the fabricated prototype demonstrate that the operating frequency of the antenna ranges from 2.52 to 2.68 GHz across four different states. The beamwidth can switch between approximately 65° and 95° in both planes. The isolation between units exceeds 25 dB, and the radiation performance is stable with high efficiency. This antenna is particularly suitable for applications in 5G indoor communications.

Implementation of an indoor optical camera communication and localization fusion system using infrared LED markers.

Recently, with the development of communication and positioning technologies, progressively higher demands have been placed on the timeliness of indoor communication and the effectiveness of indoor positioning. This paper proposes a low-cost and full-time domain coverage indoor communication and localization fusion system that uses an infrared camera to identify mobile LEDs based on region of interest optical camera communication (RoI-OCC) and calculate three-dimensional (3D) world coordinates based on perspective-n-point (PnP) algorithm. An intermediate delimiter modulation-demodulation method is designed to achieve asynchronous OCC. In processing infrared images, a region-growth-based absolute-directional-mean-difference (RG-ADMD) algorithm is developed to detect infrared targets and recover the scale. Additionally, a local-contrast-method-based Lucas-Kanade (LCM-LK) optical flow estimation algorithm is designed to track infrared targets and determine the centroid coordinates of pixels. In a 5×5 m experimental area, the established system can achieve a target detection recall rate of over 85%, the asynchronous OCC with error-free transmission and an average 3D positioning accuracy of 2.01 cm under a LCM-LK tracking algorithm.

Thirty two port super wideband diversity antenna for indoor communications

This paper introduces a novel design featuring a thirty-two port diversity antenna with an elliptical shape, fed by an asymmetric coplanar waveguide (CPW). The antenna incorporates uneven meander lines, tailored for super-wideband (SWB) applications. The structure of the unit cell is of an elliptical patch with an elliptical slot, and it is connected to a rectangular stub and asymmetric meander line. The size of the single element is 22 mm × 20 mm, and it operates from 3 to 40 GHz. The bandwidth dimension ratio of the unit cell is 3911, bandwidth ratio is 13.33:1, and fractional bandwidth is 172.09%. The single element is developed into a 3-D thirty-two port diverse antenna, composed of a horizontal plane and four planes perpendicular to it. The diverse antenna has a peak gain of 12.5 dBi and an efficiency of 94%. The computed envelope correlation coefficient (ECC), as determined using S-parameters and far-field measurements, is less than 0.1. The attained diversity gains (DGs) of the developed MIMO antenna are above 9.9 dB in terms of both S-parameter and far-field computations. The obtained thirty-two port diverse antenna channel capacity loss (CCL) is below 0.25 bits/s/Hz. The mean effective gain (MEG) of the constructed thirty-two port antenna is below 2. To validate the appropriateness of the developed thirty-two port antenna for wireless indoor environment, an enclosure made of acrylonitrile butadiene styrene (ABS) is crafted and fabricated, and the characteristics of the proposed diverse antenna are investigated.

Performance improvement of THz MIMO antenna with graphene and prediction bandwidth through machine learning analysis for 6G application

This article provides the findings of a study that integrated simulation, an RLC equivalent circuit, and machine learning (ML) techniques to improve wireless indoor communications clusters with future 6 G applications. The antenna being presented is constructed on a polyimide substrate. It exhibits an isolation of 27 dB and has a bandwidth of 4.331 THz, ranging from 0.631 THz to 4.962 THz. Along with its small size (95.52 × 227.24) µm2, it boasts an impressive maximum gain of 13.3 dB and an efficiency rating of 95 %. The ECC value drops below 0.0002 when the DG goes over 9.99. An advanced design system (ADS) creates a model like the proposed MIMO antenna to compare the return loss caused by CST (Computer Simulation Technology). Subsequently, following extensive data sampling with CST MWS (Microwave Studio) simulation, we employed supervised regression ML techniques. Gaussian process regression demonstrates exceptional accuracy, reaching almost 99 %, as evidenced by the high R-square and var scores. Additionally, it achieves the lowest error, less than one, while predicting bandwidth. The proposed antenna demonstrates strong potential as a formidable contender for 6 G THz band applications, as evidenced by the outcomes of the CST simulations and the prognostications derived from the machine learning techniques.

Resource Control in Active IRS-Aided 6G IoT Networks with Use Case in Smart Indoor Communication

The IoT ecosystem involves connected smart devices that support massive amount of data for processing and further analysis. The proliferating massive IoT network demands network connectivity, robust communication links and computational resources which puts huge load on the network. To overcome the communication overhead in the IoT landscape while offering optimal fault tolerance is the main challenge. This paper presents an intelligent solution for improving the communication efficiency of IoT network using active IRS technology. An active IRS aided communication framework is proposed which offers enhanced network connectivity by enabling controlled reflection amplitude. An algorithm is proposed which associates optimal active IRS to each AP-node link such that signal-to-interference-plus-noise ratio (SINR) is maximized. It is observed that the proposed association scheme in active IRS system offers an improvement of 19.04% in achievable rate over random association at AP transmit power [Formula: see text] of 20[Formula: see text]dBm and IRS amplification power [Formula: see text] of 4[Formula: see text]dBm. Furthermore, the system outage probability is carried out with change in [Formula: see text] and amplification gain [Formula: see text]. The mean channel power is also evaluated for different IRS densities and AP densities under different IRS reflecting elements [Formula: see text], [Formula: see text] and [Formula: see text]. In the end, the performance comparison with passive IRS system and system with no IRS assistance is carried out. A use case scenario of active IRS-aided system in smart indoor communication is also discussed.

Channel Measurement, Characterization, and Modeling for Terahertz Indoor Communications Above 200 GHz

Channel Measurement, Characterization, and Modeling for Terahertz Indoor Communications Above 200 GHz

A Review of Security Methods in Light Fidelity Technology

Light fidelity (Li-Fi) technology is a communication technology using visible light. Li-Fi technology solves the problem of radio frequency bandwidth shortage in wireless fidelity (Wi-Fi) and is more secure considering the wall is impenetrable to the light. However, an exception can be made if a vulnerability emerges when having indoor communication, and the wall leak may induce the hacker to attack the network. Thereby, the encryption data is needed in one or all layers of Li-Fi technology to secure data. This paper presents a review of security threats that need to secure data when using Li-Fi technology to transfer data, and the used methods to secure data in Li-Fi technology are elaborated. A descriptive analysis is also used for related work. As a result, the challenges in Li-Fi technology with encryption used in one of those layers of Li-Fi technology are identified.

Experimental validation of the appropriate channel model for an indoor Visible Light Communication system

Visible light communication (VLC) is a technology with significant potential to revolutionize indoor communication performance and satisfy the demands of fifth-generation (5G) and beyond technologies. To achieve an efficient VLC system that delivers optimal performance and coverage, it is imperative to create a reliable channel model. As a result, this research is centered around the evaluation of existing channel models for planning the VLC network coverage within indoor environments. The primary focus of this study is to enforce three types of channel models, Line of Sight (LoS), Nakagawa’s first reflection model, and the Spherical model through MATLAB simulations and obtain simulation results by varying the distance parameter. Furthermore, this research intends to implement a physical prototype representing a real-world scenario, and thereby determine the nearest channel model that aligns with the physical measurements obtained from the physical prototype.

Single-Layer Frequency-Selective Surface on Window Glass for 5G Indoor Communications

Single-Layer Frequency-Selective Surface on Window Glass for 5G Indoor Communications

A droplet-shape inspired wideband bow-tie dielectric resonator antenna for sub-6 GHz and IoT applications

In this article, an approach to realizing a dielectric resonator based bow-tie shaped antenna for the sub-6 GHz, 5G and IoT applications is discussed that utilizes droplet-shaped radiators for its two arms. The droplet-shaped radiating element is systematically derived to obtain a wider bandwidth response by truncating the sides of an aperture-coupled cylindrical DRA operating at HE11δ mode. The proposed bow-tie dielectric resonator antenna (DRA) is a modified dipole structure that uses a balanced line to differentially feed the two radiating segments to attain an overall wideband characteristics. A wideband matching balun circuit facilitates the antenna feeding which produces equal amplitude signals with 180° phase difference at its two output ports throughout the band of interest. The measurement of the proposed antenna confirms that it can serve several 5G bands like n77 (3300–4200 MHz), n78 (3300–3800 MHz), n48 (3550–3700 MHz) and n79 (4400–5000 MHz) with an overall wide bandwidth of 42.7% in the sub-6 GHz range. This planar configuration has a realized gain value ≥7.5 dBi within 3.37–3.91 GHz and it remains higher than 6 dBi almost throughout the working bandwidth of 3.18–4.91 GHz with considerably wide beamwidth. This broadband DRA has a consistent broadsided radiation pattern with cross-polarization discrimination (XPD)> 20 dB and its radiation efficiency varies between 60%–70% within 3.2–4.8 GHz. The antenna occupies a volume 1.2λ×1.2λ×0.1λ corresponding to its lower frequency of operation and it can support many more significant applications including WiMAX (3.3–3.8 GHz), Citizens Broadband Radio Service (CBRS) (3.55–3.7 GHz) and LTE (3.41–3.5 GHz uplink/3.51–3.6 GHz downlink). All these characteristics make this antenna a suitable candidate for use in transceiver modules for indoor communication, base stations, and vehicular communication.

Joint optimal beam forming and resource allocation in intelligent reflecting surface aided wireless power transfer rate splitting multiple access system

SummaryThe intelligent reflecting surface (IRS) has recently become the most promising technology to achieve maximum beam‐forming gain with a simultaneous wireless information and power transfer (SWIPT) system. Many existing studies perform a single IRS deployment or utilize space division multiple access (SDMA) and non‐orthogonal multiple access (NOMA) schemes. However, the existing schemes face high time complexity and block signal transmission for larger indoor communications. Hence, this article introduces a dual IRS‐aided multiuser SWIPT system by implementing rate‐splitting multiple access (RSMA) systems. To enhance the minimum achievable rate and ensure the minimum harvesting energy (HE), this study proposes a joint successive convex approximation with an integrated optimization algorithm (SCA‐IOA). The proposed algorithm jointly optimizes the reflecting beam forming and power splitting (PS) coefficient of all the users effectively. The simulation results demonstrate the effectiveness of the proposed techniques and produce an outstanding performance for deploying dual IRS and implementing RSMA compared to traditional SDMA and NOMA systems.

Reduced resource competition based on mCAP and FD‐OZCZ code for VLCP system

AbstractThe advancement of smart cities and intelligent industries has accentuated the necessity for reliable indoor communication and precise indoor positioning. In response, this paper presents an innovative integrated system for indoor visible light communication and positioning, designed to facilitate robust communication and pinpoint accuracy in positioning for indoor applications. We incorporate multiband carrierless amplitude and phase (CAP) modulation to mitigate interference between communication and positioning subcarriers. Unlike the conventional orthogonal frequency division multiplexing‐based subcarrier modulation (OFDM‐SCM), CAP demonstrates reduced out‐of‐band interference and a diminished peak‐to‐average power ratio (PAPR). Moreover, we introduce the frequency domain optical zero correlation zone (FD‐OZCZ) code, integrated within the CAP signal to optimize the distribution of positioning subcarriers. Simulation outcomes substantiate that our proposed CAP, augmented with FD‐OZCZ, outperforms OFDM‐SCM systems in delivering reliable communication and exceptional positioning accuracy.

Performance Evaluation of Collision Avoidance for Multi-node LoRa Networks based on TDMA and CSMA Algorithm

LoRa can be used as the communication technology for the intelligent monitoring system. However, LoRa is usually used for outdoor communication. The usage of LoRa as indoor communication has many challenges. One of the challenges is that collision happens when using standard LoRa devices with only one channel. The algorithms based on TDMA (Time-division Multiple Access) and CSMA (Carrier-sense Multiple Access) protocols can be used to address this challenge. These two algorithms can be modified by applying the device that is the center of the network (gateway) as a central control and the data transmitter (sensor node) as a passive device. The test was conducted on the Intelligent Laboratory Monitoring System to evaluate this design on a multi-node LoRa network. RSSI testing proves that the distance and building interference affect the signal strength or RSSI of sensor nodes, so the average RSSI value is -73.75 with an RSSI threshold of value -106. The gateway successfully collected each sensor node data with an average success of about 64.953%. The experiment results show the success rate of the CSMA-based algorithm is 10% versus 100% in TDMA-based algorithm; the delay is 4125 ms for CSMA-based and 428.3 ms for TDMA-based. This result means that the CSMA-based algorithm is more complex, takes more time to process the data than the TDMA-based algorithm, has a low success rate, and is more prone to collisions.

Adjustable THz Absorber Exploiting Nested Graphene Disk-Ring

This work introduces a THz dual-band absorber with the capability of being tuned via external stimulation. A nested disk-ring graphene pattern is proposed on top of the lossless substrate while the other side of the substrate is coated by a thick layer of gold. The proposed absorber is modeled using an equivalent circuit model (ECM) and also simulated by the full wave method. A perfect match between the circuit model and numerical full wave simulation highlights the developed circuit modeling. Since the circuit modeling can reduce CPU time and need memory considerably. The impedance-matching concept interpretations are discussed in detail. Ample simulation results show the dual-band operation of the proposed absorber at 2THz and 10THz, while an interesting tuning capability is provided by changing chemical potentials. Such a simple and adjustable wave absorber is in demand for numerous applications ranging from medical imaging to indoor communication.

Terahertz Uygulamaları için Grafen Malzemesine Dayalı Mikroşerit Bowtie Anten Tasarımı ve Optimizasyonu

The developments of the wireless communications technology, the Terahertz (THz) frequency band of the electromagnetic spectrum becomes promising and recently has the researchers’ attention to be utilized in several applications such as medical, indoor communications for personal networks, and the military applications. The main issues in this frequency band are the construction of a compact, high-performance antenna design; as in this frequency band, the material properties for conduction decrease as the frequency increases, and therefore the performance of the antenna diminishes. In this paper, we propose a graphene-based bowtie microstrip antenna, the performance of the graphene material in the THz frequency band is analysed based on the finite integration of the Computer Simulation Technology (CST) software. The graphene-based bowtie patch printed on a silicon dioxide substrate with a fully copper ground plane printed on its bottom. The proposed graphene plasmonic bowtie antenna covers a range of 0.1-10 THz band frequency with good gain in the range of 2-19 dBi in the mentioned band.