Point process modeling of wildfire hazard in Los Angeles County, California

The Burning Index (BI) produced daily by the United States government's National Fire Danger Rating System is commonly used in forecasting the hazard of wildfire activity in the United States. However, recent evaluations have shown the BI to be less effective at predicting wildfires in Los Angeles County, compared to simple point process models incorporating similar meteorological information. Here, we explore the forecasting power of a suite of more complex point process models that use seasonal wildfire trends, daily and lagged weather variables, and historical spatial burn patterns as covariates, and that interpolate the records from different weather stations. Results are compared with models using only the BI. The performance of each model is compared by Akaike Information Criterion (AIC), as well as by the power in predicting wildfires in the historical data set and residual analysis. We find that multiplicative models that directly use weather variables offer substantial improvement in fit compared to models using only the BI, and, in particular, models where a distinct spatial bandwidth parameter is estimated for each weather station appear to offer substantially improved fit.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS401 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

The associations of area-level crime rates and self-reported crime exposure with adolescent behavioral health

The effects of witnessing and experiencing crime have seldom been disaggregated. Little research has assessed the effect of multiple exposures to crime. We assess independent contributions of self-reported crime and area-level crime to adolescent behavioral health outcomes. Cross sectional data on 5519 adolescents from the Comprehensive Community Mental Health Services for Children and their Families Program was linked to FBI crime rate data to assess associations of mutually exclusive categories of self-reported crime exposure and area-level crime rates with mental health and substance abuse. Self-reported crime exposure was significantly associated with poorer behavioral health. Violent victimization had the largest association with all outcomes except internalizing scores. All self-reported crime variables were significantly associated with three of the outcomes. Area-level crime rates were associated with one mental health outcome. Providers should assess direct and indirect crime exposure rather than only focusing on violent victimization

UAV-Ground BS Coordinated NOMA with Joint User Scheduling, Power Allocation and Trajectory Design

We propose an unmanned aerial vehicle (UAV) ground base station (GBS) coordinated NOMA scheme where UAV and GBS jointly serve the cell-edge users. To the best of our knowledge, this is the first work to investigate air-ground BSs coordination for UAV-assisted NOMA systems, by taking advantage of the interference between UAV and GBS. Therefore, the proposed UAV-GBS coordinated NOMA scheme achieves much higher sum rate of cell-edge users than the non-coordinated UAV-assisted NOMA schemes where interference is suppressed as much as possible. The proposed scheme also outperforms GBSs coordinated NOMA due to more flexible and cost-effective interference management, thanks to the deployment of low-cost UAV BS. We conduct joint optimization of power allocation, user scheduling and UAV trajectory for the UAV-GBS coordinated system. A closed-form optimal solution to power allocation is derived. In addition, a dedicated successive interference cancellation (SIC) ordering approach is proposed. It is proven that the selection of a cell-center user with higher SIC order contributes to a higher rate of cell-edge user, based on which an SIC order based user scheduling algorithm for both cell-center and cell-edge users is presented

Beyond Non-Orthogonal Multiple Access: New Role of Constructive Interference

In this paper, we introduce a novel framework of constructive non-orthogonal multiple access (NOMA) transmission, which provides the merit of interference utilization and breaks through the constructive interference (CI)’s limitation on multiuser (MU) access capability. With dedicated synthetic successive coding and hybrid MU access designs, a novel constructive NOMA (CNOMA) precoder is proposed, which is particularly suitable for the scenario where users have heterogeneous throughput requirements. Explicitly, it makes the composite interference always beneficial to the users having high throughput requirement, while accommodating another sets of users under their subscribed reception-quality requirement. Finally, a number of fundamental properties of the CNOMA design is revealed, such as the tradeoff between utilization of MU interference and improvement of MU access capability. Simulation demonstrates that the proposed CNOMA precoder significantly outperforms the classic CI and minimum-mean-square-error precoders in throughput performance, and meanwhile obtains high access capability close to classic NOMA designs

Multicluster-Coordination Industrial Internet of Things: The Era of Nonorthogonal Transmission

The imminent industrial Internet of Things (IIoT) aims to provide massive device connectivity and support ever-increasing data demands, putting today's production environment on the edge of a new era of innovations and changes. In a multicluster IIoT, devices may suffer severe intercluster interference due to the intensive frequency reuse among adjacent access points (APs), thus deteriorating their quality of service (QoS). To address this issue, conventional multicluster coordination in the IIoT provides orthogonal code-, frequency-, time- or spatial-domain multiple access for interference management, but this results in a waste of resources, especially in the context of the explosively increased number of devices

Joint Resource Allocation for Adaptive Fuzzy Logic Based Coordinated Multi-Cell NOMA Systems

We investigate a downlink multi-cell non-orthogonal multiple access (NOMA) system with coordinated base stations (BSs) and propose a joint resource allocation (RA) scheme alongside adaptive user association to green the system. To the best of our knowledge, this is the first work to investigate joint allocation of subchannels and power for coordinated NOMA systems, while the previous work on RA for coordinated orthogonal multiple access (OMA) systems is not applicable. A serving channel gain based joint RA (SCG-JRA) algorithm is proposed, based on the theoretical proof that the total transmission power is mono-decreasing with respect to the SCGs of non-coordinated users. As for user association, an adaptive fuzzy logic (FL) based multi-criterion approach is proposed to achieve higher robustness against the combined effect of shadowing, fading and inter-cell interference, compared to the previous single-criterion based approaches. Numerical results show that the proposed SCG-JRA with adaptive FL based user association significantly outperforms the previous RA schemes assisted by single-criterion user association, in terms of energy efficiency (EE) and total transmission power, enabling a greener system

Hybrid-Mode Multiple Access for UAV-BS Assisted Communications with UL-DL Rate Balancing

In this paper, we propose an unmanned aerial vehicle (UAV) base station (BS) assisted communication system for a special event (e.g., a football game) with heterogeneous traffic demands by all users and the uplink (UL)-downlink (DL) rate balancing requirement. With respect to UAV's high mobility, we propose a hybrid mode multiple access (HMMA) strategy where both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) techniques are utilized to meet heterogeneous traffic demands. Specifically, NOMA is utilized to achieve high average data rate, and OMA helps to meet the instantaneous rate demands of users. The proposed HMMA strategy has a high degree of freedom and provides superior minimum average rate across all users and a higher user fairness than the previous work with OMA only or NOMA only, where the instantaneous rate demands of users may not always be guaranteed during UAV's flight time due to dynamic channel changes, the inter-user interference and successive interference cancellation (SIC) error propagation. Furthermore, we investigate joint UL-DL optimization for a UAV assisted wireless system. Based on the channel reciprocity of the air-ground channels, an alternative algorithm is proposed to conduct joint UL-DL optimization of bandwidth assignment and UAV trajectory to accommodate heterogeneous rate demands across users and achieve quasi-balanced average rates in UL and DL