7 research outputs found
Probability of error of OFDM systems with carrier offset in frequency-selective fading channels
Abstract-We present an analytical approach to evaluate the error probability of orthogonal frequency-division multiplexing (OFDM) systems subject to carrier frequency offset (CFO) in frequency-selective channels, characterized by Rayleigh or Rician fading. By exploiting the Gaussian approximation of the intercarrier interference (ICI), we show that the bit-error rate (BER) for quadrature amplitude modulation (QAM) can be expressed by the sum of few integrals, whose number depends on the constellation size. Each integral can be evaluated numerically, or, in Rayleigh fading, by using a series expansion that involves generalized hypergeometric functions. Simulation results illustrate that the theoretical analysis is quite accurate, especially for Rayleigh channels
Long-term changes in the breeding period diet of Bonelli's eagle (Aquila fasciata) in Sicily, Italy
Context: Dietary analyses are essential to achieve a better understanding of animal ecology. In the case of endangered species, assessing dietary requirements is crucial to improve their management and conservation. The Bonelli's eagle (Aquila fasciata) has experienced a severe decline throughout its breeding range in Europe and, in Italy, fewer than 50 pairs remain, and only in Sicily. This species is subject to major threats, including changes in landscape composition and, consequently, prey availability, which is further aggravated by the occurrence of viral diseases in the case of rabbits. Aims: To provide current data on the diet of the Bonelli's eagle in Sicily during the breeding period and to examine dietary shifts with regard to previous studies conducted in the same study area. To discuss possible implications for conservation of the Italian population of this endangered species. Methods: We used a combination of three methods, including pellet analysis, collection of prey remains, and imagery from camera-traps installed at nests, to examine the diet of 12 breeding pairs of Bonelli's eagle from 2011 to 2017. We compared this information with data collected between 1993 and 1998 in the same study area. Key results: In number, birds were the most frequently predated items (61.6%), followed by mammals (36.88%) and reptiles (1.52%). However, in terms of biomass, mammals were the main prey (65.71%), followed by birds (34.12%) and reptiles (0.17%). There was a decrease over the course of the current decade in the consumption of European wild rabbit (Oryctolagus cuniculus), which was compensated for with an increase in both dietary diversity and breadth in bird consumption, a trend not observed in the earlier study in the same region. Conclusions: Here, we provide an updated assessment of diet composition of Bonelli's eagle during the breeding period. Interestingly, we found significant differences within the study period (2011-2017) in terms of frequency of occurrence, percentage of biomass, dietary diversity and dietary breadth in a species at risk. Furthermore, we found significant differences between the two study periods in both frequency and percentage of biomass, with significant changes in the consumption of lagomorphs and birds. Implications: Our results indicated that shifts in the diet are linked to changes in prey abundance, which may be contributing to population declines in the Bonelli's eagle population in Sicily. Overall, measures aimed at increasing main dietary prey should be promoted to favour occupation of new territories and enhance vital demographic parameters (i.e. breeding success and survival rate) of Bonelli's eagle across the species range. This would be particularly important for small isolated populations such as the Sicilian one
Adaptive Channel-Tracking Method and Equalization for MC-CDMA Systems over Rapidly Fading Channel under Colored Noise
Population size and breeding performance of the Lanner Falcon Falco biarmicus in Sicily: conservation implications
Capsule: We report a significant reduction in population size and breeding success for the Lanner Falcon Falco biarmicus in Sicily, its biggest stronghold in Europe, since the latest coordinated survey.
Aims: To provide updated information on current population size of Lanner Falcon in Sicily and to compare breeding parameters with those obtained in previous studies.
Methods: We performed an intensive coordinated field survey and literature review of breeding success parameters across the species range.
Results: Overall, we monitored 126 territories throughout Sicily where the species had been reported in the last 15 years. Lanner Falcons were present only in 60 of them. Mean nest productivity (\ub1 standard deviation) was 1.09 \ub1 1.18 fledged young/checked pairs, flight rate was 2.22 \ub1 0.52 fledged young/successful pairs and breeding success was 49.0%.
Conclusions: Indirect measures aimed at preventing abandonment of occupied territories should be applied, for instance by developing a network of priority areas and slowing down degradation of the pseudo-steppe habitats by agri-environmental schemes. Additionally, direct measures aimed at preventing nest robbery, including the organization of nest guarding activities, and reduction of anthropogenic disturbance and illegal shooting, must be encouraged in order to avoid territory abandonment