Mobility management in multi-tier LiFi networks

Mobility management is an important part of the analysis and design of ultra-dense LiFi networks. This paper presents a two-tier LiFi network and analyses the cross-tier handover rate between the primary and secondary cells. For different conditions of semiangle at half illuminance of the primary and secondary cells, we propose three different coverage models for the secondary cells. Using stochastic geometry, closed-form expressions are derived for the cross-tier handover rate, ping-pong rate and sojourn time in terms of the received optical signal intensity, time-to-trigger and user mobility. The analytical models are validated with simulation results

Energy and spectral efficiency of multi-tier LiFi networks

In this paper, multi-tier LiFi networks are studied in terms of energy efficiency (EE) and spectral efficiency (SE), which are crucial metrics for LiFi system design. We derived a closed-form expression of the user association probability for different tiers using stochastic geometry based Poisson Voronoi Tessellation (PVT) LiFi network. The performance metrics of the network, EE and SE, are analyzed in terms of different parameters such as transmit power and Lambertian index. Performance evaluations and numerical results show that multi-tier LiFi networks have an optimum transmit power in which EE is maximized. Besides, increasing the transmit power does not increase SE after passing a threshold point. The resulting trade-off between EE and SE is presented

functional outcome in late adolescence/early adulthood of patients with autism spectrum disorder and its relationships with parental burnout and depression: A preliminary multi-center, cross-sectional study.

The aim of this study is to determine the functioning of adults with autism spectrum disorders (ASDs) diagnosed in childhood and depression and burnout levels among their parents. A total of 261 adults with ASDs and their parents were recruited for the study. Both parents completed the Beck Depression and Maslach Burnout Inventories and reported the functioning of their adult offspring with ASDs. Only 5.4 % of our sample reported “good” or “very good” outcomes. The most common psychiatric comorbidities were intellectual disabilities and attention-deficit/hyperactivity disorder. Maternal burnout and depression scores were significantly elevated compared to those of fathers. There is an undeniable urgent need for more research to identify the needs of adults and families suffering from ASD. Modifications for those with ASD may have to be made for support in workplaces, achieving driving licenses, using public transportation and attendance at tertiary education