Department of Electrical and Electronics Engineering
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1925
Browse
8 results
Search Results
Item Statistical Results of Multivariate Fox-H Function for Exact Performance Analysis of RIS-Assisted Wireless Communication(IEEE, 2024) Zafaruddin, S.M.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.Item Sum and Product of Multivariate Fox-H Functions: Exact Analysis for RIS-Assisted System Over Rician Fading With Imperfect CSI(IEEE, 2024) Zafaruddin, S.M.Existing performance analysis of wireless systems based on reconfigurable intelligent surfaces (RIS) over fading channels has primarily focused on providing statistical insights into the sum and product of random variables, typically represented as a single-variate Fox-H function. A research gap exists for an exact performance analysis when the statistical characterization of wireless systems, including RIS-assisted systems, requires more than a single-variate Fox-H function. In such cases, incorporating a multivariate representation becomes imperative, particularly when addressing generalized fading models and channel estimation errors, even with simpler one-parameter fading models. This paper introduces a novel approach to derive the distribution of the sum and product of independent and nonidentical distributed (i.ni.d) random variables characterized by the multivariate Fox-H function. We also establish a general framework for an exact analysis of ergodic capacity and average signal-to-noise ratio (SNR) when the multivariate Fox-H function describes the statistics of the channel. Applying the derived results, we conduct an exact performance analysis of outage probability and ergodic capacity, exemplified by RIS-assisted communication over Rician fading channels with imperfect phase compensation and channel estimation errors. Computer simulations validate the exact analysis and illustrate the performance of the RIS-assisted system under various practically relevant scenarios, enhancing the overall performance assessment.Item Meijer-G Function With Continued Product and Integer Exponent: Performance of Multi-Aperture UOWC System Over EGG Turbulence(IEEE, 2024) Zafaruddin, S.M.; Bandyopadhyay, Jayendra N.Signal transmission over underwater optical wireless communication (UOWC) experiences the combined effect of oceanic turbulence and pointing errors statistically modeled using the sum of two Meijer-G functions. There is a research gap in the exact statistical analysis of multi-aperture UOWC systems that use selection combining diversity techniques to enhance performance compared to single-aperture systems. In this paper, we develop a general framework for the continued product and positive integer exponent for the sum of Meijer-G functions to analyze the exact statistical performance of the UOWC system in terms of multivariate Fox-H function for both independent and non-identically distributed (i.ni.d.) and independent and identically distributed (i.i.d.) channels. We also approximate the performance of a multi-aperture UOWC system with i.i.d. channels using the single-variate Fox-H function. Using the generalized approach, we present analytical expressions for average bit-error rate (BER) and ergodic capacity for the considered system operating over exponential–generalized gamma (EGG) oceanic turbulence combined with zero-boresight pointing errors. We also develop asymptotic expressions for the average BER at a high signal-to-noise (SNR) to capture insights into the system's performance. Our simulation findings confirm the accuracy of our derived expressions and illustrate the impact of turbulence parameters for i.ni.d. and i.i.d. models for the average BER and ergodic capacity, which may provide a better estimate for the efficient deployment of UOWC.Item Simplified Performance Analysis of OWC System Over Atmospheric Turbulence with Pointing Error(IEEE, 2020) Zafaruddin, S.M.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.Item Performance Analysis of Dual-Hop THz Wireless Transmission for Backhaul Applications(IEEE, 2021) Zafaruddin, S.M.THz transmissions suffer from pointing errors due to antenna misalignment and incur higher path loss from the molecular absorption in addition to the channel fading. In this paper, we employ an amplify-and-forward (AF) dual-hop relaying to mitigate the effect of pointing errors and extend the range of THz wireless system for backhaul connectivity. We provide statistical analysis on the performance of the considered system by deriving analytical expressions for the outage probability, average bit-error-rate (BER), average signal-to-noise ratio (SNR), and a lower bound on the ergodic capacity over independent and identical (i.i.d) α−μ fading combined with the statistical effect of pointing errors. Using computer simulations, we validate the derived analysis of the relay-assisted system. We also demonstrate the effect of the system parameters on outage probability and average BER with the help of diversity order. We show that data rates up to several Gbps can be achieved using THz transmissions, which is desirable for next-generation wireless systems, especially for backhaul applications.Item Fixed-Gain AF Relaying for RF-THz Wireless System Over α-κ-μ Shadowed and α-μ Channels(IEEE, 2022-05) Zafaruddin, S.M.Recent research investigates the decode-and-forward (DF) relaying for mixed radio frequency (RF) and terahertz (THz) wireless links with zero-boresight pointing errors. We analyze the performance of a fixed-gain amplify-and-forward (AF) relaying for the RF-THz link to interface the access network on the RF technology with wireless THz transmissions. We develop probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end SNR for the relay-assisted system in terms of bivariate Fox’s H function considering α - μ fading for the THz system with non-zero boresight pointing errors and α - κ - μ shadowed ( α -KMS) fading model for the RF link. Using the derived PDF and CDF, we present exact analytical expressions of the outage probability, average bit-error-rate (BER), and ergodic capacity of the considered system. We also analyze the outage probability and average BER asymptotically for a better insight into the system behavior at high SNR. We use simulations to compare the performance of the AF relaying having a semi-blind gain factor with the recently proposed DF relaying for THz-RF transmissions.Item Performance of Dual-Hop Relaying for THz-RF Wireless Link Over Asymmetrical α-μ Fading(IEEE, 2021-10) Zafaruddin, S.M.Terahertz (THz) frequency bands can be promising for data transmissions between the core network and access points (AP) for next-generation wireless systems. In this paper, we analyze the performance of a dual-hop THz-RF wireless system where an AP facilitates data transmission between a core network and user equipment (UE). We consider a generalized model for the end-to-end channel with independent and not identically distributed (i.ni.d.) fading model for THz and RF links using the α - μ distribution, the THz link with pointing errors, and asymmetrical relay position. We derive a closed-form expression of the cumulative distribution function (CDF) of the end-to-end signal to noise ratio (SNR) for the THz-RF link, which is valid for real-valued μ for a generalized performance analysis over THz fading channels. Using the derived CDF, we analyze the performance of the THz-RF relayed system using decode-and-forward (DF) protocol by deriving closed-form expressions of outage probability, moments of SNR, average BER, and a tight approximation of ergodic capacity in terms of system parameters. We develop asymptotic analysis on the ergodic capacity, outage probability, and average BER in the high SNR region and derive the diversity order of the system. We also analyze the considered system with an i.i.d. model and develop simplified performance to provide insight on the system behavior analytically under various practically relevant scenarios. Simulation and numerical analysis show a significant effect of fading parameters of the THz link and a nominal effect of normalized beam-width on the performance of the relay-assisted THz-RF system.Item Performance analysis of optical wireless communications with aperture averaging over exponentiated Weibull turbulence with pointing errors(Elsevier, 2021-12) Chaubey, V.K.; Zafaruddin, S.M.Aperture averaging (AA) is a potential technique to reduce the effect of atmospheric turbulence in optical wireless communications (OWC). Although there is significant research on point-like detectors, there is a gap in the study on the analytical performance evaluation of OWC systems with AA over atmospheric turbulence and pointing errors. In this paper, we analyze the performance of a single-link OWC system by considering the three-parameter exponentiated Weibull (EW) model for the atmospheric turbulence and the zero boresight fading model for pointing errors. We derive analytical expressions for moments of signal-to-noise ratio (SNR), ergodic capacity, outage probability, average bit-error-rate (BER), and average energy consumption under the combined effect of atmospheric turbulence and pointing errors in terms of system parameters. To provide insights on the system behavior, we develop asymptotic bounds at high SNR on the performance of the considered system. We also derive analytical expressions for the performance of OWC system under the atmospheric turbulence with negligible pointing errors. We demonstrate the performance of OWC system over EW turbulence with a comparison to the performance obtained using the Gamma–Gamma (GG) model and demonstrate the tightness of the derived performance bounds through numerical and simulation analysis.