An Approach to Computation based on Discrete Dynamical Systems

, M.Sc. Thesis Sharif University of Technology Dastgheib, Doratossadat (Author) ; Daneshgar, Amir (Supervisor)

Abstract

In this thesis, based on an idea of A. Daneshgar [On mathematical foundations of soft computing, 11th IFSC, Zahedan, Iran(2011).], we propose a general framework to model computation which is based on discrete dynamical systems. In this regard, we formulate and justify local property as the key concept characterizing computation machines within this framework. We show that our model covers most known computation machines as classical and BSS models, Petri nets, cellular automata, Markov chains and etc. . We also study the computational power of our machine based on a variant of restrictions imposed on its different components, as its memory, or its control, and we suggest that such a...

Mobility-Aware Resource Allocation in Hybrid Visible Light Communication and 5G Radio Access Technologies Networks

, M.Sc. Thesis Sharif University of Technology Dastgheib, Mohammad Amir (Author) ; Salehi, Javad (Supervisor)

Abstract

Visible light communication (VLC) uses huge license-free spectral bandwidth of visible light for high-speed wireless communication. Since each VLC access point covers a small area, handovers of mobile users are inevitable. In order to deal with these handovers, developing fast and effective resource allocation algorithms is a challenge. this paper introduces the problem of mobility-aware optimization of resources in hybrid VLC and 5G radio access technologies networks using the T-step look-ahead policy and employing the notion of handover efficiency. It is shown that the handover efficiency can correlate the overall performance of the network with future actions based on the mobility of...

Anticipatory approaches for resource allocation in LiFi networks

, Article 2nd West Asian Colloquium on Optical Wireless Communications, WACOWC 2019, 27 April 2019 through 28 April 2019 ; 2019 , Pages 157-161 ; 9781728137674 (ISBN) Dastgheib, M. A ; Beyranvand, H ; Salehi, J. A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

As a promising solution for future indoor access networks, resource allocation in Visible light communication or LiFi networks is subject to lots of researches. An interesting approach for network algorithm design is to use some knowledge about the future of the network. With this regards, the anticipatory design may improve the performance of the system in terms of delay and throughput. This paper reviews the state-of-the-art anticipatory algorithms proposed in the literature, given different prediction capabilities. The key element that all of these algorithms share is to find an event that correlates the current actions to the performance of the network in the future. Apart from the...

Optimal visible light communication access point placement under stationary distribution of users' mobility

, Article 9th International Symposium on Telecommunication, IST 2018, 17 December 2018 through 19 December 2018 ; 2019 , Pages 96-101 ; 9781538682746 (ISBN) Dastgheib, M. A ; Beyranvand, H ; Salehi, J. A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

Visible light communication (VLC) uses LED lights for simultaneous illumination and data transmission. The throughput of a VLC network is highly dependent on the location of VLC access points (AP). In this paper, we propose a novel optimization framework for approximately optimal VLC AP placement which takes into account the stationary distribution of users for the first time. This distribution is the result of the mobility pattern of users in an indoor environment. The proposed method is independent of the resource allocation algorithm and eliminates the need for exhaustive simulations to find the optimal location for VLC APs. Simulation results show a significant improvement in the...

Optimal placement of access points in cellular visible light communication networks: an adaptive gradient projection method

, Article IEEE Transactions on Wireless Communications ; Volume 19, Issue 10 , 2020 , Pages 6813-6825 Dastgheib, M. A ; Beyranvand, H ; Salehi, J. A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2020

Abstract

In this paper, a new approach toward the optimization of Access Point (AP) placement in cellular Visible light Communication (VLC) networks is proposed based on the projected gradient algorithm. The objective of the optimal placement problem is to maximize the average throughput of the network subject to constraints on the minimum illumination level and the minimum rate of the users. This optimization framework gives the enhanced AP deployment in case of users with static, nomadic, or completely mobile behavior. Taking the distribution of users, the receiver's field of view, reflection from walls and interference from neighboring APs into account makes the deployment problem complicated. To...

Optimization of cellular lifi network deployment for gaussian mixture user distributions

, Article 9th Iran Workshop on Communication and Information Theory, IWCIT 2021, 19 May 2021 through 20 May 2021 ; 2021 ; 9781665400565 (ISBN) Dastgheib, M. A ; Beyranvand, H ; Zolala, E ; Salehi, J.A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2021

Abstract

The long-term performance of LiFi networks significantly depends on the location of access points. The optimized placement can be determined based on the distribution of users in the room. In this paper, we investigate the placement optimization for average throughput maximization in the presence of asymmetric distributions. In particular, we represent users' distribution in the indoor environment by the Gaussian mixture model, which is powerful and computationally convenient. Then we obtain the optimized deployment for different scenarios using gradient ascent algorithm. The results show that optimization of deployment significantly improves the average throughput of the network. As the...

Mobility-Aware resource allocation in vlc networks using t-step look-ahead policy

, Article Journal of Lightwave Technology ; Volume 36, Issue 23 , 2018 , Pages 5358-5370 ; 07338724 (ISSN) Dastgheib, M. A ; Beyranvand, H ; Salehi, J. A ; Maier, M ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2018

Abstract

Visible light communication (VLC) uses huge license-free spectral bandwidth of visible light for high-speed wireless communication. Since each VLC access point covers a small area, handovers of mobile users are inevitable. In order to deal with these handovers, developing fast and effective resource allocation algorithms is a challenge. This paper introduces the problem of mobility-aware optimization of resources in VLC networks using the T-step look-ahead policy and employing the notion of handover efficiency. It is shown that the handover efficiency can correlate the overall performance of the network with future actions based on the mobility of users. Due to the stationary nature of...

On fundamental limits of energy-efficient signaling in visible light communication systems

, Article IEEE Wireless Communications Letters ; Volume 12, Issue 10 , 2023 , Pages 1731-1735 ; 21622337 (ISSN) Dastgheib, M. A ; Zolala, E ; Beyranvand, H ; Salehi, J. A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2023

Abstract

In this letter, we investigate the fundamental limits of energy efficiency in Visible Light Communication (VLC) systems, which rely on Light Emitting Diodes (LEDs) for both illumination and communication. Despite their promise for indoor wireless communications, VLC systems face challenges due to increased energy consumption compared to illumination-only systems. Our analysis focuses on the electrical behavior of key components in VLC transmitter circuits to address this issue. We introduce the problem of capacity per unit cost in optical intensity channels, aiming to maximize information transmission while minimizing power consumption. Lower and upper bounds for energy efficiency are...

VLC Access Networks: Optimizing Access Point Placement and User Association

, Ph.D. Dissertation Sharif University of Technology Dastgheib, Mohammad Amir (Author) ; Salehi, Jawad (Supervisor) ; Beyranvand, Hamzeh (Supervisor)

Abstract

In this dissertation, the optimization problem of visible light communication (VLC) access networks is discussed and investigated. Firstly, by examining the fundamental concepts in VLC systems, the channel capacity is analyzed, and the concept of capacity per unit cost is introduced to improve energy consumption. The appropriate relationship for channel capacity in optimization studies is also explored. In this regard, we reached a new distribution for transmitted signals, which, by reducing up to approximately 92% of the additional energy required for data communication, increases energy efficiency in visible light communication systems up to 98%, bringing the energy consumption of the...

Removal of Volatile Chlorinated Compounds (TCE,PCE) from Groundwater with Nanostructure of NZVI

, M.Sc. Thesis Sharif University of Technology Ghasemipoor, Amir (Author) ; Bastani, Darioush (Supervisor) ; Seifkordi, Ali Akbar (Supervisor) ; Samiee, Leila (Supervisor) ; Dastgheib, Mohammad Mehdi (Co-Advisor)

Abstract

In recent years, the reductive dehalogenation of the chlorinated hydrocarbons using nanoscale zerovalent iron (nZVI) represents a promising approach for underground remediation. Regarding commercialization of this technique, instability and unknown nature of nZVI particle are still challenging tasks that should be considered.
In the current work, Nanoscale zero-valent iron (nZVI) and palladized iron (Pd/Fe) bimetallic particles were synthesized and employed to react with chlorinated compound (PCE) in water to investigate its degradation behaviors. The results show that the reactant ratio, stabilizer amount and temperature are the main parameters with the considerable effect on PCE...