3,481 research outputs found
Energy harvesting Aided Device-to-Device Communication in the Over-Sailing Heterogeneous Two-Tier Downlink
No full textThis is research data associated with recently accepted IEEE Access journal titled 'Energy Harvesting Aided Device-to-Device Communication in the Over-Sailing Heterogeneous Two-Tier Downlink'.
Abstract: Device-to-Device (D2D) communication and heterogeneous networks have been considered as promising techniques for alleviating the demand both for increased spectral resources and for additional infrastructure required for meeting the increased tele-traffic. For the sake of improving both the bandwidth efficiency and the network capacity of heterogeneous cellular networks constituted by multiple tiers, a direct D2D communication is arranged between a pair of nearby devices without involving the base station (BS), whilst reusing the cellular resources. We aim for maximising the sum-rate of the energy harvesting (EH) aided D2D links in a two-tier HetNet by superimposing their messages on the downlink resources of mobile users (MUs), which is achieved without unduly degrading MU's throughput. Specifically, our optimization problem relies on the objective function of maximising the D2D sum-rate based on the joint assignment of both the resource blocks (RBs) and of the transmission power for both the EH aided D2D links and for the MUs. This non-convex optimization problem, which is intractable in its original form, is then converted to a tractable convex problem, which is then analyzed by invoking the method of Lagrange multipliers of constrained optimization. As a result, an algorithmic solution defined as 'joint optimization of RB and power allocation (JORPA)' is proposed, which jointly allocates the RBs and power for the D2D links, whilst relying on the results of Lagrangian constrained optimization, when the base stations (BSs) of different tiers obey one of the following regimes: (a) orthogonal, (b) co-channel and (c) the proposed co-orthogonal channel deployments. We also propose low complexity heuristic methods for optimising the D2D transmit power while defining the D2D-MU matching heuristically and vice versa. The performance of both the JORPA algorithm as well as of the low-complexity heuristic algorithms is quantitatively analysed using our simulation results for different channel deployments relying on diverse network parameter settings. As expected, orthogonal deployment performs best, followed by the co-orthogonal and co-channel deployments. Moreover, the throughput experienced by the MUs in presence of D2D communication is guaranteed by our co-orthogonal scheme as well as orthogonal scheme, while co-channel suffers a marginal degradation when compared with throughput threshold. We also demonstrate that our 'equal power allocation (EPA)' heuristic method is capable of achieving 96% of the sum-rate achieved JORPA while other heuristic methods perform less well, implying that the optimization of the D2D-MU matching is indeed crucial for the system considered.
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Energy harvesting aided device-to-device communication networks
No full textWith the ever growing demands of power and bandwidth by users, energy and spectral efficiency emanated as key criteria for designing future wireless networks. Therefore, in this thesis energy harvesting (EH) aided device-to-device (D2D) communication is designed for improving both the key design criteria, which is an intricate journey from the realm of individual analysis of EH and D2D communication to that of amalgamating the two techniques.Specifically, with the widespread use of energy hungry smart devices, these devices become dis-functional due to outage of batteries, which can be avoided by introduction of EH capability at these nodes. In this context, an energy efficient successive relaying based network is conceived using rechargeable source and relay nodes having limited buffers for both their energy and data storage. An optimal and sub-optimal transmission policies are designed for the maximisation of the network throughput with non-causal knowledge of energy arrivals by the deadline.On the other hand, for exploiting the spectrum efficiently, D2D communication is invoked which brings in new interference scenarios that may be circumvented by incorporating fractional frequency reuse (FFR) or soft frequency reuse (SFR) in OFDMA cellular networks. By carefully considering the downlink resource reuse of the D2D links, beneficial frequency allocation schemes are proposed, when the macrocell has employed FFR or SFR. The coverage probability and the capacity of D2D links are analytically derived under the proposed schemes.It is imperative to integrate the benefits of EH and D2D communication aided systems for creating unparalleled opportunities in emerging applications. Therefore, a system is designed that comprises of EH aided D2D links relying on downlink resource reuse with the goal of maximizing the sum-rate of the D2D links, without degrading the quality of service (QoS) requirement of the MUs. A pair of joint resource block and power allocation algorithms are proposed for the D2D links, when there is non-causal (off-line) and causal (on-line) knowledge of the EH profiles at the D2D transmitters. For the sake of further accentuating design flexibility and alleviating the demands of increased spectral resources, previously designed EH aided D2D communication is investigated in conjunction with heterogeneous network (HetNet). An algorithmic solution is proposed with the aim of maximising the sum-rate of these D2D links in the downlink of two-tier HetNet without unduly degrading MU’s throughput, when two tiers share spectrum under following regimes: (a) orthogonal, (b) co-channel and (c) the proposed coorthogonal. Low complexity heuristic methods are also proposed, which demonstrate that the optimization of the D2D-MU matching is indeed crucial for the system considered
Energy harvesting aided device-to-device communication in the over-sailing heterogeneous two-tier downlink
No full textDevice-to-Device (D2D) communication and heterogeneous networks have been considered as promising techniques for alleviating the demand both for increased spectral resources and for additional infrastructure required for meeting the increased tele-traffic. For the sake of improving both the bandwidth efficiency and the network capacity of heterogeneous cellular networks constituted by multiple tiers, a direct D2D communication is arranged between a pair of nearby devices without involving the base station (BS), whilst reusing the cellular resources. We aim for maximising the sum-rate of the energy harvesting (EH) aided D2D links in a two-tier heterogeneous network by superimposing their messages on the downlink resources of mobile users (MUs), which is achieved without unduly degrading MU's throughput. Specifically, our optimization problem relies on the objective function of maximising the D2D sum-rate based on the joint assignment of both the resource blocks (RBs) and of the transmission power for both the EH aided D2D links and the MUs. This non-convex optimization problem, which is intractable in its original form, is then converted to a tractable convex problem, which is then analyzed by invoking the method of Lagrange multipliers of constrained optimization. As a result, an algorithmic solution defined as joint optimization of RB and power allocation (JORPA) is proposed, which jointly allocates the RBs and power for the D2D links, whilst relying on the results of Lagrangian constrained optimization, when the base stations (BSs) of different tiers obey one of the following regimes: (a) orthogonal; (b) co-channel; and (c) the proposed co-orthogonal channel deployments. We also propose low complexity heuristic methods for optimizing the D2D transmit power, while defining the D2D-MU matching heuristically and vice versa. The per formance of both the JORPA algorithm as well as of the low-complexity heuristic algorithms is quantitatively analyzed using our simulation results for different channel deployments relying on diverse network parameter settings. As expected, orthogonal deployment performs best, followed by the co-orthogonal and co-channel deployments. Moreover, the throughput experienced by the MUs in presence of D2D communication is guaranteed by our co-orthogonal scheme as well as orthogonal scheme, while co-channel suffers a marginal degradation when compared with throughput threshold. We also demonstrate that our equal power allocation heuristic method is capable of achieving 96% of the sum-rate achieved by JORPA while other heuristic methods perform less well, implying that the optimization of the D2D-MU matching is indeed crucial for the system considered
Energy harvesting aided device-to-device communication underlaying the cellular downlink
No full textThroughput maximization for a buffer-aided successive relaying network relying on energy harvesting
No full textsj-docx-1-jicm-10.1177_08850666211067509 - Supplemental material for Association of Surge Conditions with Mortality Among Critically Ill Patients with COVID-19
No full textSupplemental material, sj-docx-1-jicm-10.1177_08850666211067509 for Association of Surge Conditions with Mortality Among Critically Ill Patients with COVID-19 by Adam B. Keene, Andrew J. Admon, Samantha K. Brenner, Shruti Gupta, Deepa Lazarous, David E. Leaf, Hayley B. Gershengorn and in Journal of Intensive Care Medicine</p
sj-docx-1-dhj-10.1177_20552076211039032 - Supplemental material for Change in cardiometabolic risk factors among Asian Indian adults recruited in a mHealth-based diabetes prevention trial
No full textSupplemental material, sj-docx-1-dhj-10.1177_20552076211039032 for Change in cardiometabolic risk factors among Asian Indian adults recruited in a mHealth-based diabetes prevention trial by Shruti Muralidharan, Harish Ranjani, Ranjit Mohan Anjana, Yashdeep Gupta, Samita Ambekar, Varsha Koppikar, N Jagannathan, Sidhant Jena, Nikhil Tandon, Steven Allender and Viswanathan Mohan in Digital Health</p
Performance analysis of device-to-device communication underlaying dense networks (DenseNets)
No full textGiven the exponential proliferation of mobile devices and broadband services, there is a pressing need to amalgamate multiple technologies accommodating infrastructural changes for meeting the ever-increasing demands of user capacity. Therefore, in this paper, we propose the integration of proximity-based direct device-to-device (D2D) communication with the network densification concept. In this paper, we consider user-centric non-overlapping clusters associated with the closest access point for serving user equipment (UE) in the downlink under limited availability of orthogonal resource blocks (RBs), while the D2D links also reuse these downlink RBs. We analytically derive the coverage probability as well as the average transmission rate of D2D links under the proposed model, which results in a complex interference scenario. The performance results verify that our analytical results closely match with simulations for different parametric settings. The impact of the presence of D2D links on the coverage probability of the UEs is also quantified, revealing that the UEs' performance is only modestly affected under the proposed system model
Resource allocation for D2D links in the FFR and SFR aided cellular downlink
No full textDevice-to-device (D2D) communication underlying cellular networks, allows direct transmission between two devices in each other's proximity that reuse the cellular resource blocks in an effort to increase the network capacity and spectrum efficiency. However, this imposes severe interference that degrades the system's performance. This problem may be circumvented by incorporating fractional frequency reuse (FFR) or soft frequency reuse (SFR) in OFDMA cellular networks. By carefully considering the downlink resource reuse of the D2D links, we propose beneficial frequency allocation schemes, when the macrocell has employed FFR or SFR as its frequency reuse technique. The performance of these schemes is quantified using both the analytical and simulation results for characterizing both the coverage probability and the capacity of D2D links under the proposed schemes that are benchmarked against the radical unity frequency reuse scheme. The impact of the D2D links on the coverage probability of macrocellular users (CUs) is also quantified, revealing that the CUs performance is only modestly affected under the proposed frequency allocation schemes. Finally, we provide insights concerning the power control design in order to strike a beneficial tradeoff between the energy consumption and the performance of D2D lin
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