Low-power wide-area networks (LPWAN) have substantially improved the Internet of Things (IoT). LoRaWAN is a potential technology for IoT applications because it uses low-power, long-distance communication and offers excellent availability with low energy consumption. LoRaWAN power consumption can be reduced using the pure Aloha protocol at the MAC level. Optimizing orthogonal transmission parameters is still a major difficulty for enhancing network performance, even though they reduce packet loss and prevent collisions, especially in dynamic and heterogeneous networks. However, the challenge of random channel selection in LoRaWAN communication often leads to inefficient resource utilization and degraded network performance. This paper proposes a novel game-theoretic approach for optimal channel selection in LoRaWAN networks. Our method leverages real-time Received Signal Strength Indicator (RSSI) data and a non-cooperative game theory model to dynamically select channels, thereby improving throughput and reducing packet loss. Through extensive simulations and a realworld testbed, we demonstrate that our proposed mechanism outperforms existing approaches such as the Online Decision algorithm and MFMSF. Specifically, it achieves up to$22 \backslash \%$improvement in throughput,$15 \backslash \%$higher packet delivery ratio, and$18 \backslash \%$reduction in latency, while consuming up to$25 \backslash \%$less energy under heavy and dynamic traffic conditions. This work offers a significant advancement in enhancing the scalability and reliability of LoRaWAN networks, paving the way for more efficient IoT communications.

Current statistical channel models for Terahertz (THz) wireless communication primarily concentrate on the sub-THz band, mostly with$\alpha-\mu$and Gaussian mixture fading distributions for short-term fading and deterministic modeling for atmospheric absorption. In this paper, we develop a generalized statistical model for signal propagation at THz frequencies considering random path-loss employing Gamma distribution for the molecular absorption coefficient, short-term fading charac-terized by the$\alpha-\eta-\kappa-\mu$distribution, antenna misalignment errors, and transceiver hardware impairments. The proposed model can handle various propagation scenarios, including indoor and outdoor environments, backhauVfronthaul situations, and complex urban settings. Using Fox's H-functions, we present the probability density function (PDF) and cumulative distribution function (CDF) that capture the combined statistical effects of channel impairments. We analyze the outage probability of a THz link to demonstrate the analytical tractability of the proposed generalized model. We present computer simulations to demonstrate the efficacy of the proposed model for performance assessment with the statistical effect of atmospheric absorption.

Existing research provides statistical results on the sum of single-variate Fox-H functions to analyze the performance of diversity receivers and reconfigurable intelligent surfaces (RIS) based wireless systems. There is a research gap in exact performance analysis when more than a single-variate Fox-H function represents the statistical characterization of wireless systems. In this paper, we propose a novel approach to obtain the distribution of the sum of independent and non-identically distributed (i.ni.d) random variables characterized by the multi-variate Fox-H function. Further, we develop a general framework for an exact analysis of the ergodic capacity when the multivariate Fox-H function characterizes the statistics of signal-to-noise ratio (SNR). We apply the derived results to conduct an exact performance analysis of outage probability and ergodic capacity, taking an example of RIS-assisted communication over Rician fading channels with phase errors. We conduct computer simulations to validate the exact analysis and demonstrate performance of the RIS-assisted system under various practically relevant scenarios for a better performance assessment.

Establishing end-to-end connectivity of Internet of Things (IoT) network with the core for collecting sensing data from remote and hard-to-reach terrains is challenging. In this article, we analyze the performance of an IoT network integrated with a wireless backhaul link for data collection. We propose a solution that involves a self-configuring protocol for aggregate node (AN) selection in an IoT network, which sends the data packet to an unmanned aerial vehicle (UAV) over radio frequency (RF) channels. We adopt a novel hybrid transmission technique for wireless backhaul employing opportunistic selections combining (OSC) and maximal ratio combining (MRC) that simultaneously transmits the data packet on mmWave (mW), free space optical (FSO), and terahertz (THz) technologies to take advantage of their complementary characteristics. We employ the decode-and-forward (DF) protocol to integrate the IoT and backhaul links and provide physical layer performance assessment using outage probability and average bit-error rate (BER) under diverse channel conditions. We also develop simplified expressions to gain a better understanding of the system’s performance at a high signal-to-noise ratio (SNR). We provide computer simulations to compare different wireless backhaul technologies under various channel and SNR scenarios and demonstrate the performance of the data collection using the integrated link.

Recent research has focused on single antenna radiofrequency (RF) and terahertz (THz) wireless systems to mix the access link with the backhaul. In this paper, we evaluate the performance of a mixed RF-THz system employing multiple antenna-assisted access point (AP) for the RF link and single-antenna THz transmissions. We employ an equal gain combining (EGC) receiver at the AP and use the fixed-gain amplify and forward (AF) relaying protocol to interface the RF and THz links. We derive analytical expressions for probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end SNR for the considered system assuming independent and non-identically distributed (i.ni.d.) $\alpha - \mu$ distribution to model for both RF and THz channels and pointing errors in the THz link. We analyze the system performance using the outage probability, average bit error rate (BER), and ergodic capacity involving bivariate Fox’s H-function. We use the residue method to develop asymptotic analysis using Gamma functions to show the impact of the various channel and system parameters on the outage probability and average BER in the high SNR regime. We use computer simulations to depict the scaling of the performance with an increase in the number of antennas at the AP for signal reception in the access link.

Reconfigurable intelligent surface (RIS) can provide stable connectivity for vehicular communications when direct transmission becomes significantly weaker with dynamic channel conditions between an access point and a moving vehicle. In this paper, we analyze the performance of a RIS-assisted vehicular network by coherently combining received signals reflected by RIS elements and direct transmissions from the source terminal over double generalized Gamma (dGG) fading channels. We present analytical expressions on the outage probability and average bit-error rate (BER) performance of the considered system by deriving exact density and distribution functions for the end-to-end signal-to-noise ratio (SNR) resulted from the finite sum of the direct link and product of channel coefficients each distributed according to the dGG. We also develop asymptotic analysis on the outage probability and average BER to derive diversity order for a better insight into the system performance at high SNR. We validate the derived analytical expressions through numerical and simulation results and demonstrate scaling of the system performance with RIS elements and a comparison to the conventional relaying techniques and direct transmissions considering various practically relevant scenarios.

The use of multiple reconfigurable intelligent surfaces (RIS) between a source and destination can enhance the performance of wireless communications over severe shadowing environment by creating line-of-sight (LOS) connectivity. This paper analyzes the performance of a multiple RIS empowered multi-hop transmission for a wireless system. We develop an analytical framework to derive statistical results of the signal-to-noise ratio (SNR) of the multi-RIS communication by considering independent and non-identical double generalized gamma (dGG) fading channels in each hop. We analyze the performance of the considered multi-RIS system by deriving exact analytical expressions of the outage probability, average bit-error rate (BER), and ergodic capacity in terms of Fox’s H-function. We present asymptotic analysis and diversity order of the outage probability in the high SNR regime to provide a better insight into the system performance. We use computer simulations to demonstrate the effect of multiple RIS modules, and fading parameters on the RIS-aided multi-hop transmissions for the considered communication system.

Underwater optical communication (UWOC) is a potential solution for broadband connectivity in oceans and seas for underwater applications providing high data rate transmission with low latency and high reliability. Recent measurement campaigns suggest generalized Gamma distribution as a viable model for oceanic turbulence. In this paper, we analyze the performance of a UWOC system by modeling the vertical underwater link as a multi-layer cascaded channel, each distributed according to independent but not identically distributed (i.ni.d.) generalized Gamma random variables and considering the zero bore-sight model for pointing errors. We derive analytical expressions for probability density function (PDF) and cumulative distribution function (CDF) for the signal-to-noise ratios (SNR) of the combined channel and develop performance metrics of the considered UWOC system using outage probability, average bit error rate (BER), and ergodic capacity. We also derive the asymptotic expressions for outage probability and average BER to determine the diversity order of the proposed system for a better insight into the system performance. We use Monte-Carlo simulation results to validate our exact and asymptotic expressions and demonstrate the performance of the considered underwater UWOC system using measurement-based parametric data available for turbulent oceanic channels.

Mitigating channel fading and transceiver impairments are desirable for high-speed terahertz (THz) wireless links. This paper analyzes the performance of a multi-antenna THz wireless system by considering the combined effect of pointing errors and fluctuating two-ray (FTR) fading model. We provide a statistical characterization of the maximal ratio combining (MRC) receiver over independent and nonidentical (i.ni.d.) channel conditions in terms of multi-variate Fox’s H by deriving density and distribution functions of the signal-to-noise ratio (SNR) of a single-link THz link using incomplete Gamma function. We develop exact analytical expressions of outage probability, average bit-error-rate (BER), and ergodic capacity for both single-antenna and MRC receivers. We also present the diversity order of the system by deriving asymptotic expressions for outage probability and average BER at high SNR to obtain insights into the system performance. We validate our derived analytical expressions with Monte-Carlo simulations and demonstrate the effect of various system and channel parameters on the performance of single and multi-antenna THz wireless communications.

The existing relay-assisted terahertz (THz) wireless system is limited to dual-hop transmission with pointing errors and short-term fading without considering the shadowing effect. This paper analyzes the performance of a multihop-assisted backhaul communication mixed with an access link under the shadowed fading with antenna misalignment errors. We derive novel probability density and distribution functions of the signal-to-noise ratio (SNR) of the multihop link employing channel-assisted (CA) and fixed-gain (FG) amplify-and-forward (AF) relaying for each hop by considering independent but not identically distributed (i.ni.d)$\alpha $-$\mu $fading channel with pointing errors. We present analytical expressions for the outage probability and average bit-error-rate (ABER) and develop asymptotic analysis in high SNR regime to derive the diversity order for both CA-multihop and FG-multihop backhaul links. We use the derived results of the multihop systems to analyze the statistical performance of the integrated backhaul-access relaying for both uplink and downlink transmission considering the generalized-$K$shadowed fading model in the access link. We also present exact and asymptotic expressions of the outage probability for the considered mixed system. We perform computer simulations to provide design and deployment aspects of employing multiple relays to enhance THz wireless transmissions.

Reconfigurable intelligent surface (RIS) is an excellent use case for line-of-sight (LOS) based technologies such as free-space optical (FSO) communications. In this paper, we analyze the performance of RIS-empowered FSO (RISE-FSO) systems by unifying Fisher-Snedecor (${\mathcal{F}}$), Gamma-Gamma ($\cal {GG}$), and Malága ($\cal {M}$) distributions for atmospheric turbulence with zero-boresight pointing errors over deterministic as well as random path-loss in foggy conditions with heterodyne detection (HD) and intensity modulation/direct detection (IM/DD) methods. By deriving the probability density function (PDF) and cumulative distribution function (CDF) of the direct-link (DL) with the statistical effect of atmospheric turbulence, pointing errors and random fog, we develop exact expressions of PDF and CDF of the resultant channel for the RISE-FSO system. Using the derived statistical results, we present exact expressions of outage probability, average bit-error-rate (BER), ergodic capacity, and moments of signal-to-noise ratio (SNR) for both DL-FSO and RISE-FSO systems. We also develop an asymptotic analysis of the outage probability and average BER and derive the diversity order of the considered systems. We validate the analytical expressions using Monte-Carlo simulations and demonstrate the performance scaling of the FSO system with the number of RIS elements for various turbulence channels, detection techniques, and weather conditions.

The use of Terahertz (THz) frequency bands for data transmissions between the core network and an access point can be promising for next generation wireless systems. In this paper, we analyze the performance of a dual-hop relaying for THz-RF wireless link for backhaul applications. Considering the α−µ fading channel and a statistical model of pointing errors, we derive a novel closed-form expression of the cumulative distribution function (CDF) of the signal-to-noise ratio (SNR) for the THz link, which is also valid for non-integer values of µ. Using the CDF, we derive analytical expressions of the end-to-end SNR and lower bound on ergodic capacity of a decode-and-forward (DF) assisted THz-RF relaying in terms of system parameters. Using analytical results of the direct link and computer simulations, we demonstrate that the THz-RF relaying is a viable technology for wireless backhaul, providing a significant increase of almost 25% in the spectral efficiency, compared to the direct transmissions.

Impulse noise presents a severe performance bottleneck in multicarrier systems. For digital subscriber lines (DSL), the use of a common-mode (CM) sensor is a viable technique to mitigate the impulse noise that couples into the useful differential-mode (DM) signal. In this paper, we use time and frequency domain approaches to develop algorithms using the joint processing of CM and DM signals and analyze the performance of dual-sensor based interference cancellation schemes for downstream DSL systems. First, we consider the frequency domain approach and analyze the performance of a per-tone impulse noise canceler without requiring an impulse detector. We derive closed-form expressions on the performance of canceler in various interference scenarios in terms of system parameters. Next, we develop a novel per-symbol time-domain impulse noise canceler by simultaneous estimation of the CM2DM transfer function and the CM impulse noise using a limited number of null carriers. The proposed algorithm eliminates the issues of convergence of the per-tone canceler and stationarity of the impulse noise over multiple symbols. Using derived analytical expressions, we show that the proposed canceler effectively mitigates the impulse noise on a per-symbol basis. We also demonstrate the performance of the considered canceler schemes using measurement and simulation results.

Optical wireless communication (OWC) is highly vulnerable to the atmospheric turbulence and pointing error. Performance analysis of the OWC system under the combined channel effects of pointing errors and atmospheric turbulence is desirable for its efficient deployment. The widely used Gamma-Gamma statistical model for atmospheric turbulence, which consists of Bessel function, generally leads to complicated analytical expressions. In this paper, we consider the three-parameter exponentiated Weibull model for the atmospheric turbulence to analyze the ergodic rate and average signal-to-noise ratio (SNR) performance of a single-link OWC system. We derive simplified analytical expressions on the performance under the combined effect of atmospheric turbulence and pointing errors in terms of system parameters. We also derive approximate expressions on the performance under the atmospheric turbulence by considering negligible pointing error. In order to evaluate the performance at high SNR, we also develop asymptotic bounds on the average SNR and ergodic rate for the considered system. We demonstrate the tightness of derived expressions through numerical and simulation analysis along with a comparison to the performance obtained using the Gamma-Gamma model.

Channel allocation is the task of assigning channels to users such that some objective (e.g., sum-rate) is maximized. In centralized networks such as cellular networks, this task is carried by the base station (BS) which gathers the channel state information (CSI) from the users and computes the optimal solution. In distributed networks such as ad-hoc and device-to-device (D2D) networks, no BS exists and conveying global CSI between users is costly or simply impractical. When the CSI is time varying and unknown to the users, the users face the challenge of both learning the channel statistics online and converging to a good channel allocation. This introduces a multi-armed bandit (MAB) scenario with multiple decision makers. If two or more users choose the same channel, a collision occurs and they all receive zero reward. We propose a distributed channel allocation algorithm that each user runs and converges to the optimal allocation while achieving an order optimal regret of O (log T ), where T denotes the length of time horizon. The algorithm is based on a carrier sensing multiple access (CSMA) implementation of the distributed auction algorithm. It does not require any exchange of information between users. Users need only to observe a single channel at a time and sense if there is a transmission on that channel, without decoding the transmissions or identifying the transmitting users. We demonstrate the performance of our algorithm using simulated LTE and 5G channels.

We propose an iterative crosstalk cancellation scheme based on the generalized minimal residual (GMRES) algorithm for large-scale digital subscriber line (DSL) systems. The proposed scheme does not require channel inversion and stores fewer vectors for crosstalk cancellation. We analyze the convergence of the GMRES algorithm and derive computable bounds on the residual error and signal-to-noise ratio in terms of system parameters at each iteration for upstream DSL systems. We show that the GMRES algorithm typically requires a single iteration for very large vectored systems to achieve crosstalk-free performance for the very high-speed DSL (VDSL) frequencies and only a few more in the highest frequency bands of the G.fast spectrum. This yields significant complexity savings and reduction in memory storage, compared to the zero forcing scheme under certain conditions.

The use of common-mode (CM) sensor as an interference-alone reference is a viable technique to mitigate an external interference that couples into the useful differential-mode (DM) signal. In this paper, we derive performance bounds on a joint CM-DM based dual sensor interference cancellation scheme in frequency domain and investigate the impact of the CM sensor parameters on the performance of the downstream DSL system under different scenarios of external interference. We derive a tight lower bound on the capacity using parameters available in real time, and show that the optimal capacity can be achieved with a single CM sensor even in the presence of multiple interference under certain conditions on coupling transfer functions. By considering a minimum-mean square (MMSE) based canceler scheme, we derive closed form expressions on the noise variance at the output of the canceler in terms of system parameters of the CM and DM sensors. We show that the canceler can achieve the interference-free performance in various types of external interference provided a higher interference to noise ratio at the CM sensor. Measurement results from a VDSL CPE and computer simulations are presented to demonstrate the performance of the considered canceler scheme.

Linear zero‐forcing (ZF) canceller does not perform well in the presence of alien crosstalk (AXT) while the receivers based on minimum‐mean‐square‐error (MMSE) criterion require perfect knowledge of the noise covariance matrices. In this study, the authors consider the use of a constrained linear minimum‐output energy (MOE) receiver in the presence of self‐crosstalk and AXT in upstream vectored very high‐speed digital subscriber line systems, that does not require knowledge of the noise correlation matrices and can be trained using the received signals without the use of training sequences. They derive bounds on the performance of the MOE receiver in the digital subscriber line environment and show that it reaches the MMSE performance for self‐crosstalk cancellation. They also show that the performance of the proposed receiver lies in between that of the ZF receiver and the non‐linear ZF generalised decision feedback equaliser receiver. An adaptation of the canceller coefficients using MOE algorithm shows comparable performance to that of the least mean squares algorithm. The effect of noise correlation on the capacity has also been highlighted via the Cramer‐Rao lower bound. Computer simulations are presented to verify the analytical results and demonstrate the performance of the proposed receiver.