Researcher:
Iqbal, Muhammad Shahid

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PhD Student

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Muhammad Shahid

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Iqbal

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Iqbal, Muhammad Shahid

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Now showing 1 - 10 of 14
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    Publication
    Scheduling and relay selection for full-duplex wireless powered cooperative communication networks
    (Institute of Electrical and Electronics Engineers Inc., 2020) Department of Electrical and Electronics Engineering; N/A; N/A; Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Kazmi, Syed Adil Abbas; Iqbal, Muhammad Shahid; Faculty Member; PhD Student; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 7211; N/A; N/A
    In this manuscript, we consider a full-duplex wireless powered cooperative communication system where the users communicate with a hybrid access point through relays. We formulate an optimization problem with the objective to minimize the total transmission time through user scheduling and relay selection while considering the traffic demand, energy causality and initial battery levels of the users. The formulated optimization problem is a mixed integer non-linear programming problem, hence difficult to solve for the global optimal solution. As a solution strategy, we decompose the problem into sub problems: time allocation, scheduling and relay selection. In the time allocation problem; the schedule and relays are assumed to be pre-known, we derive the optimal solution by using the optimality analysis. For the scheduling problem; we assume that users know their relays, we determine the optimal schedule. For the relay selection problem; users transmit their information in a pre-determined order, we determine the optimal relays for each user. For the overall scheduling and relay selection problem, we propose a heuristic algorithm which iteratively determines the scheduling and relay selection in polynomial time by using the optimal solutions of the individual relay selection and scheduling problems. Through simulations, we demonstrate that the scheduling length can be significantly reduced through proper scheduling and relay selection. The proposed algorithm performs very close to the optimal solution for different maximum user transmit power, network densities, initial battery levels and hybrid access point power levels.
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    Total transmission time minimization through relay selection for full-duplex wireless powered cooperative communication networks
    (Springer Science and Business Media Deutschland GmbH, 2020) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Kazmi, Syed Adil Abbas; Iqbal, Muhammad Shahid; Ergen, Sinem Çöleri; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211
    We consider a relay based full-duplex wireless powered cooperative communication network which consists of a hybrid access point (HAP), N users and K decode-and-forward relays with energy harvesting capability. We propose an optimization framework for relay selection with the objective of minimizing the total transmission time subject to energy causality and user traffic demand constraints. The formulated optimization problem is a mixed integer non-linear programming problem, which is difficult to solve for the global optimal solution in polynomial-time. As a solution strategy, we decompose the proposed optimization problem into two sub-problems: time allocation problem and relay selection problem. We derive the optimal solution of the time allocation problem by using convex optimization techniques. For the relay selection problem, based on the optimality analysis, we propose a polynomial-time heuristic algorithm, which minimizes the total transmission time by allocating the best relay to each user. Through simulations, we illustrate that the proposed algorithm outperforms the conventional predetermined relay allocation scheme and performs very close to the optimal solution for different network densities, HAP power values, and initial battery levels.
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    Attenuation-based hybrid RF/FSO link using soft switching
    (2021) Minhas, Abid Ali; Khan, Muhammad Saeed; Henna, Shagufta; N/A; Iqbal, Muhammad Shahid; Researcher; Graduate School of Sciences and Engineering; N/A
    Due to high data rates, license-free spectrum, and immunity to electromagnetic interference, free-space optical (FSO) links are being considered as a potential candidate to meet the ever-increasing traffic demands of users. The FSO links remain less explored, as their performance depends on environmental conditions such as dust, fog, and clouds. Such conditions do not affect the radio frequency (RF) links in a similar way; however, RF resources are scarce. As an ultimate solution to this performance/scarcity dilemma, we propose a fuzzy logic-based hybrid architecture of FSO and RF links, which can be used to enhance reliability and resource efficiency. We present an intelligent soft switching mechanism between FSO and RF links using a fuzzy inference system to achieve the maximum link reliability and provide heterogeneous wireless services.
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    Peak to average power ratio based spatial spectrum sensing for cognitive radio systems
    (Elsevier, 2017) Hussain, Sajjad; Ghafoor, Abdul; N/A; Iqbal, Muhammad Shahid; PhD Student; Graduate School of Sciences and Engineering; N/A
    The recent convergence of wireless standards for incorporation of spatial dimension in wireless systems has made spatial spectrum sensing based on Peak to Average Power Ratio (PAPR) of the received signal, a promising approach. This added dimension is principally exploited for stream multiplexing, user multiplexing and spatial diversity. Considering such a wireless environment for primary users, we propose an algorithm for spectrum sensing by secondary users which are also equipped with multiple antennas. The proposed spatial spectrum sensing algorithm is based on the PAPR of the spatially received signals. Simulation results show the improved performance once the information regarding spatial diversity of the primary users is incorporated in the proposed algorithm. Moreover, through simulations a better performance is achieved by using different diversity schemes and different parameters like sensing time and scanning interval.
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    Optimal power control, scheduling, and energy harvesting for wireless networked control systems
    (IEEE-Inst Electrical Electronics Engineers Inc, 2021) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Karadağ, Göksu; Iqbal, Muhammad Shahid; Ergen, Sinem Çöleri; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211
    Communication system design for wireless networked control systems (WNCSs) requires strict timing, reliability and lifetime guarantees despite limited battery resources and the non-idealities introduced by wireless networking such as delays. In this paper, we introduce radio frequency (RF) energy harvesting paradigm into WNCS framework for the first time in the literature. We study the optimal power control, energy harvesting and scheduling problem with the objective of providing maximum level of adaptivity under periodicity, delay and reliability requirements. We show that the power allocation problem is separable from the scheduling problem at optimality and provide the exact expression for optimal power control. The scheduling problem is then formulated as a mixed integer linear programming (MILP) problem and proven to be NP-Hard. For the scheduling, we propose polynomial-time heuristic algorithms motivated by the analogy between scheduling sensor nodes with energy harvesting requirements over time units and jobs with sequence dependent setup times on identical machines. We prove the theoretical worst-case bound for the performance of these heuristics. We show via extensive simulations that the proposed algorithms perform close-to-optimal and significantly better than Earliest Deadline First (EDF) algorithm in terms of adaptivity, delay, reliability and average runtime.
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    Relay selection and throughput maximization for full duplex wireless powered cooperative communication networks
    (Ieee, 2021) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Kazmi, Syed Adil Abbas; Iqbal, Muhammad Shahid; Ergen, Sinem Çöleri; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211
    Cooperative communication using energy harvesting (EH) nodes promises significant improvement in network throughput, coverage, and reliability. This work studies a full-duplex (FD) wireless powered cooperative communication network (WPCCN), in which the users communicate to a hybrid access point (HAP) via decode-and-forward (DF) EH relay nodes. We present an optimization framework for the relay selection problem with an objective of maximizing the sum throughput of the FD-WPCCN, for the first time in the literature. The formulated optimization problem is a mixed integer non-linear programming problem (MINLP), which is difficult to solve for global optimal solution. As a solution strategy, we first analyze the problem for a given relay allocation and prove that it is a convex problem. We solve the problem for the optimal solution by using the Karush-Kuhn-Tucker conditions. Then, for the relay selection problem, we present a polynomial time heuristic algorithm based on the allocation of relay with the best channel conditions to each user. Through extensive simulations, we show that the proposed algorithm performs close to the optimal solution for various network parameters such as different HAP transmission power values, network sizes, and initial battery level of the nodes. We observe that the sum throughput of the network can be increased significantly by using a proper relay selection technique.
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    Performance of free space optical terrestrial link under dense fog conditions
    (Polish Acad Sciences Inst Physics, 2018) Yasir, S. M.; Khan, M. S.; Wahid, A.; Mushtaq, M. T.; Memon, M. I.; Siraj, M.; N/A; Iqbal, Muhammad Shahid; PhD Student; Graduate School of Sciences and Engineering; N/A
    Free-space optical links use modulated beam of light to transmit high amount of data from transmitter to receiver to get line-of-sight communication link. Free-space optical is cost effective solution to provide higher data rate to end-users. Free-space optical links are also considered as a better alternative to RF links due to their advantages of low power consumption and higher data rate of the range Gbps, and are highly secure to electromagnetic interference. Despite of having all these advantages free-space optical links are highly affected by the severe weather conditions like fog, rain, snow, smoke and dust or aerosol particles suspended in air. Fog is one of a major challenge for free-space optical to achieve carrier class availability and causes high amount of attenuation. In this paper we presented the performance analysis of free-space optical links by estimating signal-to-noise ratio, bit error rate, under fog conditions during winter season in Lahore, Pakistan.
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    Throughput maximization for full duplex wireless powered cooperative communication network
    (Ieee, 2022) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Kazmi, Syed Adil Abbas; Iqbal, Muhammad Shahid; Ergen, Sinem Çöleri; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211
    Higher network throughput, increased coverage area and reliability are some of the significant improvements promised by the energy harvesting (EH) cooperative communication. This paper considers a two-hop full duplex (FD) multi-relay multi-user wireless powered cooperative communication network (WPCCN), in which the EH capable relays and users transmit their information to an energy broadcasting hybrid access point (HAP). We present an optimization framework for the relay selection and scheduling of the users. The objective is to maximize the sum throughput of FD- WPCCN, considering an on-off transmission scheme, in which the relays and users either transmit at a constant power or remain silent. The formulated optimization problem is a mixed integer non-linear programming problem, which is difficult to solve for the global optimum. As a solution strategy, we first present the polyno-mial time heuristic relay selection algorithm for a predetermined schedule of the users by studying the characteristics of optimal relay allocation solution of the optimization problem. Then, we propose a polynomial time heuristic scheduling algorithm by investigating the characteristics of the optimal scheduling solution of the optimization problem. Through extensive simulations, we demonstrate that the proposed algorithms perform close to the optimal solution for different HAP power values, network sizes, battery levels of the nodes, and transmit power values of the relays and the users. We observe that the throughput can be increased significantly by selecting an appropriate relay and optimal transmission order of the users.
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    Publication
    Throughput maximization for full duplex wireless powered communication networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2020) Sadi, Yalçın; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Iqbal, Muhammad Shahid; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211
    In this paper, we consider a full duplex wireless powered communication network where multiple users with RF energy harvesting capabilities communicate to a hybrid energy and information access point. An optimization framework is proposed with the objective of maximizing the sum throughput of the users subject to energy causality and maximum transmit power constraints considering a realistic energy harvesting model incorporating initial battery levels of the users. The joint optimization of power control, time allocation and scheduling is mathematically formulated as a mixed integer non linear programming problem which is hard to solve for a global optimum. The optimal power and time allocation and scheduling decisions are investigated separately based on the optimality analysis on the optimization variables. Optimal power and time allocation problem is proven to be convex for a given transmission order. Based on the derived optimality conditions, we propose a fast polynomial-time complexity heuristic algorithm. We illustrate that the proposed algorithm performs very close-to-optimal while significantly outperforming an equal time allocation based scheduling scheme.
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    PublicationOpen Access
    Throughput maximization in discrete rate based full duplex wireless powered communication networks
    (Wiley, 2020) Şadi, Yalçın; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Iqbal, Muhammad Shahid; Faculty Member; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/A
    In this study, we consider a discrete rate full-duplex wireless powered communication network. We characterize a novel optimization framework for sum throughput maximization to determine the rate adaptation and transmission schedule subject to energy causality and user transmit power. We first formulate the problem as a mixed integer nonlinear programming problem, which is hard to solve for a global optimum in polynomial-time. Then, we investigate the characteristics of the solution and propose a polynomial time heuristic algorithm for rate adaptation and scheduling problem. Through numerical analysis, we illustrate that the proposed scheduling algorithm outperforms the conventional schemes such as equal time allocation half-duplex and on-off transmission schemes for different initial battery levels, hybrid access point transmit power and network densities.