To enable ultra-high throughputs while addressing the potential blockage problem, maintaining an adaptive access point (AP) planning is critical to mmWave networking. By investigating the hidden ...interaction between the environment map and the placement of mmWave APs, we develop an adaptive AP planning (E-app) approach that can accurately sense the environment dynamics, reconstruct the obstacle map, and then predict the placements of mmWave APs adaptively. Specifically, our solution leverages mmWave radio itself to sniff the unacceptable performance degradation through sensing only a small fraction of observation points that are identified by a sparsity-aware analytical model, thereby accurately triggering a prediction module for AP positioning when necessary. Extensive evaluations show a very high prediction accuracy for our solution, which can provide around 25% improvement on user throughput performance in mmWave WLANs. This intelligent AP-planning framework well handles the environment dynamics that affect the average-case network performance, which is of utmost interest for network deployers because of its usage convenience and adaptivity.
In a Wireless Local Area Network (WLAN), devices have limited battery capacity. To improve the energy efficiency, we propose a new Medium Access Control (MAC) protocol to perform selective energy ...transfer request based on the amount of residual energy of a device in a WLAN with IEEE 802.11 Distributed Coordination Function (DCF). By supplying the energy only to the device requiring energy harvesting, the deterioration in network throughput during energy harvesting in a wireless network is minimized. We present a new energy Markov chain model to analyze the throughput and the energy efficiency of the proposed method. We confirm that the throughput and the energy efficiency of the proposed method is improved.
Long-term evolution (LTE) and wireless local area network (WLAN) are often presented as opposing technologies. Hence, efficient partitioning of the spectrum resources carries critical importance for ...achieving the coexistence of these on the unlicensed spectrum band. In this paper, we firstly develop an online spectrum partitioning algorithm, which needs little signal transmission and exchange between coordination manager and networks. Then, we focus on the convergence analysis of the online spectrum partitioning algorithm, which is difficult due to the time-varying wireless channels. To overcome this challenge, we model the algorithm and network dynamics as the stochastic differential equations (SDE) and show that the algorithm convergence is equivalent to the stochastic stability of a virtual stochastic dynamic system constructed by the SDEs. Then, we give the sufficient condition about the algorithm convergence and the upper bound on the tracking error of the spectrum partitioning algorithm under exogenous variations of time-varying channel state information (CSI). Based on the insights of the impact of time-varying CSI on algorithm convergence, an online compensative spectrum partitioning algorithm is developed to offset the tracking error caused by the disturbance of time-varying CSI. Through performance evaluation, we show that the coexistence performance efficiency will come at low expense of algorithm complexity and signal overhead.
For fiber optic links in the optical transmission systems of short-distance local area networks, connector loss testing is performed before the connector is implemented in the system to ensure that ...the loss budget requirements are satisfied. We propose a calculation model that can be widely used for practical application of multimode optical fiber connections in loss testing of transmission systems. The proposed model uses the measured data of the near- and far-field patterns of a launch fiber output light under arbitrary launch conditions, such as the light source. To evaluate the proposed model, the connection losses of the step- and graded-index multimode fibers were estimated for the lateral and axial displacements of the optical axis; the simulated data were found to be highly consistent with the measured data. This method is highly versatile as it can be applied to any multimode fiber type, whether step-index or graded-index multimode fiber.
Fan, Liao, and Yao (2015) recently introduced a remarkable method for increasing the asymptotic power of tests in high-dimensional testing problems. If applicable to a given test, their power ...enhancement principle leads to an improved test that has the same asymptotic size, has uniformly non-inferior asymptotic power, and is consistent against a strictly broader range of alternatives than the initially given test. We study under which conditions this method can be applied and show the following: In asymptotic regimes where the dimensionality of the parameter space is fixed as sample size increases, there often exist tests that cannot be further improved with the power enhancement principle. However, when the dimensionality of the parameter space increases sufficiently slowly with sample size and a marginal local asymptotic normality (LAN) condition is satisfied, every test with asymptotic size smaller than 1 can be improved with the power enhancement principle. While the marginal LAN condition alone does not allow one to extend the latter statement to all rates at which the dimensionality increases with sample size, we give sufficient conditions under which this is the case.
TGax aims at developing the IEEE 802.11ax protocol to provide enhanced throughput and power efficiency in dense WiFi deployment environments. The new specification shifts the focus from EDCA access ...to point coordination access, which aims at improving network utilization and power efficiency. Furthermore, it introduces, for the first time, the concept of RU allocation and orthogonal frequency division multiple access (OFDMA) techniques. The new specification addresses the spectral inefficiency in existing transmission by including schedule-based multi-user multiple-input, multiple- output (MU-MIMO) and multi-user OFDMA (MU-OFDMA) techniques to facilitate multi-user uplink transmission for high efficiency (HE) devices. However, complete adoption of the HE protocol is likely to take place over a period of time to offset the deployment cost. To ensure the coexistence of non-HE devices during the transition period, EDCA based single user transmission will remain the basic access technique and a focal point of spectral inefficiency for non-HE devices in the uplink direction. Motivated by our work on the performance of IEE 802.11ac, we propose an EDCA based uplink transmission technique for non-HE devices that allows multi-user transmission to improve spectral efficiency in coexistent WLAN networks.
In indoor localization, reliability and optimization analysis are the most vital factors to be considered. Numerous modern-day services require precise location information for their application. ...Location fingerprinting using WLAN is the most acknowledged technique for indoor localization purposes. Both accuracy and coverage can be enhanced by deploying the WLAN access points (APs) appropriately. In this article, an optimization problem is formulated for reliable localization systems. An AP deployment strategy ensuring coverage along with a selection strategy to choose an optimal configuration for reducing the localization error has been implemented. A hybrid technique is proposed to select the optimal APs configuration that merges the traditional fingerprint difference and geometric dilution of precision-based methods. A distinguishing feature of this work is the inclusion of two significant constraints, which are the consideration of walls and people attenuation factor in the optimization process. Simulations are conducted to test and verify the practicality of the proposed technique through a number of comparison test cases. The results demonstrate that our proposed technique outperforms the previously existing techniques.
Abstract
Background
Light at night (LAN) as a circadian disruption factor may affect the human immune system and consequently increase an individual’s susceptibility to the severity of infectious ...diseases, such as COVID-19. COVID-19 infections spread differently in each state in the United States (US). The current analysis aimed to test whether there is an association between LAN and COVID-19 cases in 4 selected US states: Connecticut, New York, California, and Texas.
Methods
We analyzed clustering patterns of COVID-19 cases in ArcMap and performed a multiple linear regression model using data of LAN and COVID-19 incidence with adjustment for confounding variables including population density, percent below poverty, and racial factors.
Results
Hotspots of LAN and COVID-19 cases are located in large cities or metro-centers for all 4 states. LAN intensity is associated with cases/1 k for overall and lockdown durations in New York and Connecticut (
P
< 0.001), but not in Texas and California. The overall case rates are significantly associated with LAN in New York (
P
< 0.001) and Connecticut (
P
< 0.001).
Conclusions
We observed a significant positive correlation between LAN intensity and COVID-19 cases-rate/1 k, suggesting that circadian disruption of ambient light may increase the COVID-19 infection rate possibly by affecting an individual’s immune functions. Furthermore, differences in the demographic structure and lockdown policies in different states play an important role in COVID-19 infections.
Two-way seamless communication is the key aspect of realizing the vision of smart grid. There are several standardized wired and wireless communication technologies available for various smart grid ...applications. With the recent growth in wireless communication, it can offer standardized technologies for wide area, metropolitan area, local area, and personal area networks. Moreover, wireless technologies not only offer significant benefits over wired, such as including low installation cost, rapid deployment, mobility, etc., but also more suitable for remote end applications. Several activities are going on to explore specific applications of these technologies in smart grid environment. This paper presents various smart grid applications achieved through standardized wireless communication technologies, e.g. IEEE 802.11 based wireless LAN, IEEE 802.16 based WiMAX, 3G/4G cellular, ZigBee based on IEEE 802.15, IEEE 802.20 based MobileFi, etc. Moreover, challenges related to each wireless communication technologies have been discussed in brief.
A triband circularly polarized (CP) crossed-dipole antenna is introduced for 2.4/5.2/5.8-GHz wireless local area network (WLAN) applications. It employs a single feed and only two crossed ...trident-shaped dipoles as the primary radiating elements. To achieve a compact radiator size, two techniques are utilized, namely, insertion of a meander-line segment in the middle branch of the tridents and termination of all trident arms with arrowhead-shaped tips. The crossed trident-shaped dipoles are backed by a high impedance surface (HIS) to achieve a broadband characteristic and unidirectional radiation pattern at three bands. The measured impedance bandwidths, based on the -10-dB reflection coefficient values, are 2.21-2.62 GHz (410 MHz), 5.02-5.44 GHz (420 MHz), and 5.62-5.96 GHz (340 MHz), and the measured 3-dB axial-ratio bandwidths are 2.34-2.58 GHz (240 MHz), 5.14-5.38 GHz (240 MHz), and 5.72-5.88 GHz (160 MHz). The proposed antenna exhibits right-hand circular-polarized radiation with high gain.
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