Indoor Communication Networks Research Articles

An improved WiFi sensing based indoor navigation with reconfigurable intelligent surfaces for 6G enabled IoT network and AI explainable use case

The expanding number of low cost sensors and smart devices drives the internet-of-things (IoT) ecosystem of the future. These sensing devices are connected to the internet for information exchange. The location and positioning of these nodes is very important information required in vast range of location based services like smart homes, smart healthcare, environmental monitoring, personal navigation and smart transportation. This paper presents an intelligent solution for node localization in a 6G enabled IoT network. An indoor communication network scenario is proposed in which reconfigurable intelligent surfaces (RISs) are installed to locate the sensor nodes operating in that network. The performance evaluation of the proposed scheme is carried out with optimum number of reflecting elements and optimum phase shifts. It is observed that optimized RISs with 100 reflecting elements improve the estimated localization error by 7.4% over non-optimum RISs. Also, the minimum gain of 6% in localization error is offered using equal phase shifts over random phase shifts. Further, the effect of channel conditions on the average estimation error in node locations is also elaborated. In the end, the explainable artificial intelligence (XAI) empowered indoor localization is discussed as a use case scenario and the performance comparison of the algorithms is evaluated.

Passive OFE WDM-over-POF Gigabits per Second Performance Comparison of Spatial Diversity and Spatial Multiplexing

We present a novel indoor communication network using 1-mm core diameter step-index plastic optical fibres as a feeder line, and using the light emitted by the POF-end for wireless data transmission, creating a fully passive access point (AP). This has the advantage that it does not require electrical powering, resulting in low maintenance. Due to the large numerical aperture, the light emitted by the POF is extremely divergent, thus a lens must be placed in front of the POF-end to adjust the size of the coverage area to enable users moving within the area or to increase the number of users served by the wireless link. We present a theoretical model for both multiple-input multiple-output (MIMO) transmission modes, spatial diversity (SD) and spatial multiplexing (SM) concepts, using orthogonal frequency division multiplexing (OFDM). We report the system throughput, that is estimated using the singular value decomposition (SVD) of the experimentally measured channel matrix <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {H}(f)$</tex-math></inline-formula> . We then present the experimental results applying both SD and SM concepts and make a comparison between theoretical and experimental results. We demonstrate that this passive AP concept using OFDM achieves throughputs of around 5.2 Gbps when SM is applied, and 3.8 Gbps when SD is applied. Furthermore, we use eye-safe visible light laser at the beginning of the POF feeder which, due to optical losses by POF and components, limited the wireless link to 1 m only and the coverage area to 45 cm diameter. We believe the proposed system represents a low-cost, high-capacity, highly secure, interference free wireless system, suitable for next generation for industrial and home applications.

Hybrid Beamforming in Large-scale Antenna Array for 5G Indoor Communication Network Deployments

Hybrid Beamforming in Large-scale Antenna Array for 5G Indoor Communication Network Deployments

Light-Fidelity as Next Generation Network Technology: A Bibliometric Survey and Analysis

This paper delivers a systematic review and a bibliometric survey analysis of Light-Fidelity (Li-Fi) indoor implementation in Next Generation Network (NGN). The main objective of this study is to design a communication network based on NGN-Li-Fi for the indoor implementation which aims to increase user Quality of Service (QoS). The main merits and contributions of this study are the thorough and detailed analysis of the review, both in literature surveys and bibliometric analysis, as well as the discussion of the implementation model challenges of Li-Fi in both indoor and outdoor environments. The issue articulated in an indoor communication network is the possibility of intermittent connectivity due to barriers caused by line-of-sight (LOS) between the LED transmitter and receiver, handover due to channel overlap, and other network reliability issues. To realize the full potential and significant benefits of the Next Generation Network, challenges in indoor communication such as load-balancing and anticipating network congestion (traffic congestion) must be addressed. The main benefit of this study is the in-depth investigation of surveys in both selected critical literatures and bibliometric approach. This study seeks to comprehend the implications of Next Generation networks for indoor communication networks, particularly for visible light communication channels.

Wideband hybrid precoding techniques for THz massive MIMO in 6G indoor network deployment

Terahertz (THz) communication is becoming an up-and-coming technology for the future 6G networks as it offers an ultra-wide bandwidth. Appropriate channel models and precoding techniques are indispensable to support the desired coverage and to resolve the severe path loss in THz signals. Initially, in this work, the Sub-THz channel (140 GHz) response is investigated by using NYUSIM Channel Simulator for 6G indoor office scenario.The major highlight will be on radio propagation mechanisms, which impact the network performnace in the form of path-loss, received power, time delays, azimuth AoD, Azimuth AoA, Elevation AoD, Elevation AoA and RMS delay in LOS environments. Recent hybrid precoding techniques depending upon frequency-independent phase-shifters not able to cope up with the beam split effect in THz massive MIMO systems, where the directional beams will split into various physical directions at various sub-carrier frequencies. The beam split effect will result in a serious array gain loss across the entire bandwidth, which has not been well investigated in THz massive MIMO systems. Therefore, to address this challenge, delay-phase precoding is proposed in this work. We then extensively investigate its diverse number of time delayers, varying number of antenna elements, and comparison with frequency—mmWave and Sub-THz have been discussed. Finally, the proposed delay-phase precoding techniques outperforms the other existing narrowband and wideband precoding techniques. Therefore,it is an effective technique to implement the future 6G indoor communication network deployment.

Design of Energy Efficient Hybrid VLC/RF/PLC Communication System for Indoor Networks

Integrating visible light communication (VLC) system with indoor radio frequency (RF) network is seen as a possible way of increasing the capacity and coverage of indoor networks. In such a hybrid network, the traffic generated at the indoor RF and VLC access points must be backhauled to the core network. Power line communication (PLC) technology is seen as a cost-effective backhaul (BH) solution due to its infrastructure availability in every home. In this letter, a novel system model that captures the joint effect of power and BH flow optimization for hybrid VLC/RF/PLC indoor communication network is proposed. For the proposed system model, the problem of energy efficiency (EE) maximization via power and BH flow optimization is formulated as a non-convex problem, and then transformed into a convex problem via the Dinkelbach’s approach. An energy efficient algorithm is proposed to solve this joint problem with guaranteed optimality. Simulation results are used to verify the superiority of the proposed hybrid VLC/RF/PLC system and algorithm over a conventional indoor RF system and equal power allocation benchmark scheme, respectively, in terms of network throughput, power consumption, and EE.

Directional Beam Based LED Deployment for a Short Range Indoor LED Light Communication System

Abstract There is now an increasing awareness about the possibility of health hazards due to excessive electromagnetic radiations around us within the indoor environment. Hence, the alternative communication technologies such as indoor mobile communication system based on LED lighting are gaining more attention in the present scenario. The dual use of LEDs i. e. for illumination as well as for setting up of an indoor communication network infrastructure simultaneously makes it an attractive preposition. The LED lighting based communication system is qualified to be part of green technology networks. This paper investigates the optimal LED placement strategy for such a system to optimize the overall communication system parameters including the transmit power optimization. It is observed that the overall optimization of LEDs improve the signal to noise ratio and also a significant reduction in root mean square delay at lower semi-angle values besides improving the mobile coverage area.

Low cost [formula omitted]-tunable transmitter for indoor infrared wireless communication system

Optical wireless technology provides a future-proof solution for indoor communication due to its unparallel broadband features. Different from other applications, indoor communication networks are sensitive to the cost and complexity. Indoor beam-steered infrared wireless communication system (IWC) based on wavelength division device, e.g. arrayed waveguide grating is attractive due to its low cost. However, the traditional wavelength tunable transmitter is expensive. In this paper, we propose a low-cost wavelength tunable transmitter for an indoor beam-steered IWC system. The key device of such transmitter is a simple and low cost Fabry–Perot(F–P) cavity laser. Different from the external-modulator based solutions, the proposed transmitter provides gain rather than insertion loss, which further simplifies the system design and improves the system reliability. The optimal central offset in spectrum between the modulated signal and the wavelength division devices is also investigated to improve the system performance. A 4.5 Gb/s indoor IWC system incorporating 3.2-km single mode fiber and 1.1-m free space link is experimentally demonstrated.

A cognitive TV white space-broadband power line MIMO system for indoor communication networks

Broadband power line communication (BPLC) is a promising solution to satisfy the growing data rate demands for broadband indoor communication networks. However, the BPLC transmission power spectral density (PSD) is restricted in the very high frequency (VHF) band to avoid harmful interference to the existing wireless services. In this paper, a new hybrid system is proposed utilizing BPLC and cognitive radio over TV white space (TVWS) to enhance the system capacity over BPLC in VHF, forming a VHF TVWS BPLC multiple-input multiple-output (MIMO) system. An iterative precoding algorithm is proposed to satisfy the interference limit at the TV primary user (PU) receiver (Rx) and enhance the ergodic capacity. Moreover, a power allocation algorithm is developed for the MIMO system to achieve the maximum ergodic capacity subject to the average total power constraint and limit of interference to TV PU. Simulation results demonstrate the significant enhancement in the achieved capacity by our proposed system in the VHF band compared to both previous cognitive and hybrid BPLC systems.

Improved RMS delay and optimal system design of LED based indoor mobile visible light communication system

The light emitting diode (LED) based lighting systems can be used for creation of the indoor communication network for sending information besides serving its main purpose of illumination. However, there are a number of impediments which are still under resolution in order to realize the full potential of such a system. In particular, the visible light communication (VLC) systems suffer due to high inter symbol interference (ISI) mainly on account of multi path propagation which impacts the spectral efficiency of the system. Besides ensuring ubiquitous coverage, it is also important to improve the system’s bandwidth within the indoor scenario. The optimal deployment of such systems may result in optimum resource utilization (LEDs and driver circuits etc.) to minimize the energy consumption and to achieve improved operational efficiency. In this paper, we propose two types of LED deployment strategies — centralized and distributed and compare their performances on the basis of average outage area ratio, effect of semi-angle, root mean square delay and data transmission rate. The hyper heuristic evolutionary algorithm (HypEA) has been implemented to optimize the performance of the systems to achieve full receiver mobility in the indoor environment. The experimental results show that the distributed deployment strategy is able to optimize the system performance significantly in comparison to centralized deployment strategy.

Analysis of effective capacity for visible light communication systems with mobility support

Visible light communications (VLCs) are competitive and attractive candidates for next generation indoor communication networks which are required to support mobility and guarantee delay QoS (Quality of Service) for users. User movement in VLC systems changes the propagation path, including the distance, the angle of incidence and irradiance, all of which have a significant impact on channel gain and link capacity. In this paper, we present a user mobility model for indoor VLC systems with the help of discrete time Markov chain theory. Considering a service process with temporal correlation caused by user mobility, we derive the effective capacity (EC) for VLC systems which characterizes the capacity performance subject to the user’s statistical delay QoS. Moreover, the effect of the user’s mobility on effective capacity is revealed.

15 Gbit/s indoor optical wireless systems employing fast adaptation and imaging reception in a realistic environment

Optical wireless systems are promising candidates for next-generation indoor communication networks. Optical wireless technology offers freedom from spectrum regulations and, compared to current radio-frequency networks, higher data rates and increased security. This paper presents a fast adaptation method for multibeam angle and delay adaptation systems and a new spot-diffusing geometry, and also considers restrictions needed for complying with eye safety regulations. The fast adaptation algorithm reduces the computational load required to reconfigure the transmitter in the case of transmitter and/or receiver mobility. The beam clustering approach enables the transmitter to assign power to spots within the pixel's field of view (FOV) and increases the number of such spots. Thus, if the power per spot is restricted to comply with eye safety standards, the new approach, in which more spots are visible within the FOV of the pixel, leads to enhanced signal-to-noise ratio (SNR). Simulation results demonstrate that the techniques proposed in this paper lead to SNR improvements that enable reliable operation at data rates as high as 15Gbit/s. These results are based on simulation and not on actual measurements or experiments.

Development of Protection and Control Unit for Distribution Substation

The Recently, electronics and IT technologies have been rapidly innovated and have been introduced to power system protection & control system to achieve high reliability, maintainability and more functionality. Concerning the distribution substation application, digital relays have been applied for more than 10 years. Because of a number of electronic devices used for it, product cost becomes higher. Also, products installed during the past high-growth period will be at the end of lifetime and will be replaced. Therefore, replacing market is expected to grow and the reduction of cost is demanded.Considering above mentioned background, second generation digital protection and control unit as a successor is designed to have following concepts. Functional integration based on advanced digital technologies, Ethernet LAN based indoor communication network, cost reduction and downsizing.Pondering above concepts, integration of protection and control function is adopted in contrary to the functional segregation applied to the previous system in order to achieve one-unit concept. Also the adoption of Ethernet LAN for inter-unit communication is objective. This report shows the development of second-generation digital relay for distribution substation, which is equipped with control function and Ethernet LAN by reducing the size of auxiliary transformer unit and the same size as previous product is realized.

Placing base stations in wireless indoor communication networks

More and more mobile communications comes to company sites through local (typically indoor) wireless communication networks. However, planning wireless networks is quite different from planning traditional wire-based networks. Planning must take into account the specifics of radiowave propagation at the installation site. Current systems are cellular in that a base station (i.e. a sender or transmitter) controls the links to the transceivers. Buildings require multicellular systems because walls and floors absorb part of the radio signal. Today, an experienced salesperson estimates the number and positioning of base stations. To help the salesperson, Siemens has compiled a set of guidelines based on typical scenarios. However, a scenario might not always apply, and the approach does not handle positioning the base stations well. Computer-aided planning can help ease the difficulties of planning. Toward that end, we have developed Popular (Planning Of PicocellULAr Radio). The Popular prototype lets users compute the minimal number of base stations and their location, given a blueprint of the installation site and information about the wall and ceiling materials.

Performance evaluation of preemptive polling schemes and ARQ techniques for indoor wireless networks

This paper examines a radio-based indoor communication network with a single radio channel shared by several data terminals. By enabling the terminals to communicate with each other and access the resources of a wired network, the system is a potential provider of in-building LAN-like services. In this indoor fading environment, a base-station approach is assumed. In the analysis, a two-state Markov chain model is used to model the nonstationary transmission channel. Two preemptive polling multiple-access schemes combine with ARQ error-control schemes to counteract the effects of a nonstationary transmission channel. The main idea devised is that of making the service interruption dependent on the propagation conditions of the transmission channel by monitoring the outcomes of the data packet transmission attempts. A performance comparison reveals the superiority of the preemptive polling systems with respect to a classical TDMA scheme.