Spectral Efficiency of Multi-User Adaptive Cognitive Radio Networks

In this correspondence, the comprehensive problem of joint power, rate, and subcarrier allocation have been investigated for enhancing the spectral efficiency of multi-user orthogonal frequency-division multiple access (OFDMA) cognitive radio (CR) networks subject to satisfying total average transmission power and aggregate interference constraints. We propose novel optimal radio resource allocation (RRA) algorithms under different scenarios with deterministic and probabilistic interference violation limits based on a perfect and imperfect availability of cross-link channel state information (CSI). In particular, we propose a probabilistic approach to mitigate the total imposed interference on the primary service under imperfect cross-link CSI. A closed-form mathematical formulation of the cumulative density function (cdf) for the received signal-to-interference-plus-noise ratio (SINR) is formulated to evaluate the resultant average spectral efficiency (ASE). Dual decomposition is utilized to obtain sub-optimal solutions for the non-convex optimization problems. Through simulation results, we investigate the achievable performance and the impact of parameters uncertainty on the overall system performance. Furthermore, we present that the developed RRA algorithms can considerably improve the cognitive performance whilst abide the imposed power constraints. In particular, the performance under imperfect cross-link CSI knowledge for the proposed `probabilistic case' is compared to the conventional scenarios to show the potential gain in employing this scheme

A relation between the short time variations of cosmic rays and geomagnetic field change

An event is reported of approx. 37 min periodicity in cosmic ray intensity observed at Akeno(38 deg 47 N, 138 deg 30 E. 900m above s.l., cutoff 10.4 GV) during 1300 approx. 1900 UT on April 25th, 1984, just a day before Forbush decrease of April 26th. This event seemed to be followed by the periodic variations of the geomagnetic field observed at Kakioka (36 deg 23 N, 140 deg 18 E). The regression coefficient between them was obtained approx. 0.07%/10nT. It is shown that in general the power spectral density of cosmic rays in the frequency of 0.0001 approx. 0.001Hz correlates positively with the fluctuations of geomagnetic field (Dst field) around approx. 1.2x0.0001Hz. From the analysis of 47 days data (April 14th to June 13th, 1984) the regression curve was obtained as y=0.275x sup 0.343 with the correlation coefficient of 0.48, where x and y mean Fourier components of Dst field summed over 1.04 approx. 1.39x0.001Hz and cosmic ray power spectral density averaged over 0.0001 approx. 0.001Hz

Proceedings from the Synthetic LBD International Seminar

On May 9, 2017, we hosted a seminar to discuss the conditions necessary to im- plement the SynLBD approach with interested parties, with the goal of providing a straightforward toolkit to implement the same procedure on other data. The proceed- ings summarize the discussions during the workshop

Adaptive Modulation and Coding and Cooperative ARQ in a Cognitive Radio System

In this paper, a joint cross-layer design of adaptive modulation and coding (AMC) and cooperative automatic repeat request (C-ARQ) scheme is proposed for a secondary user in a shared-spectrum environment. First, based on the statistical descriptions of the channel, closed-form expressions of the average spectral efficiency (SE) and the average packet loss rate (PLR) are presented. Then, the cross-layer scheme is designed, with the aim of maximizing the average SE while maintaining the average PLR under a prescribed level. An optimization problem is formed, and a sub-optimal solution is found: the target packet error rates (PER) for the secondary system channels are obtained and the corresponding sub-optimal AMC rate adaptation policy is derived based on the target PERs. Finally, the average SE and the average PLR performance of the proposed scheme are presented

Effects of the physical form of diet on growth performance, ascites and sudden death syndrome incidences in broiler chickens

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗThis experiment was conducted to determine the effects of the diet physical form, Mash (M), Pellet (P) and Extruded (E) on the growth performance, carcass characteristics and metabolic disorders ascites (AS) and as well as sudden death syndrome (SDS) in the broiler chickens. In this respect, feed intake (FI), weight gain (WG) and mortalitywere recorded throughout the experiment and biochemical parameters, hematology and carcass characteristics were tested at 35 and 42 days of age respectively. The results showed that with the increase of the average daily weight gain (ADWG) (p<0.01), the relative breast weight to the carcass weight (p<0.05), better feed conversion ratio (p<0.01), the lower relative cecum weight and gizzard to the carcass weight (p<0.05) were observed by applying the E diet form, as compared with the other treatments. A significant increase in the average daily feed intake (ADFI) was also observed by using the P diet form (p<0.01). Hematological parameters including hemoglobin (Hb), hematocrit (HCT), urea, uric acid, triglyceride, the ratio of low-density lipoprotein to high-density lipoprotein (LDL/HDL), very low-density lipoprotein (VLDL), enzyme activities of aspartate aminotransferase(AST) and alanine aminotransferase (ALT) of the blood serum were lowered by applying the M treatment, as compared with the other treatments (p<0.05). The results indicated that the performance and carcass characteristics were improved by the E and P diet forms; also, with raising the hematology parameters in these treatments, the mortality of ascites and SDS was increased

The study of intensity and frequency of posttraumatic stress disorder (PTSD) resulting from war in Ilam city

Post-traumatic stress disorder (PTSD) is a set of a person's reactions to stresses which are beyond one's mental capacity and precedes a severe stress. The aim of this Research was to study the intensity and frequency of posttraumatic stress disorder (PTSD) resulting from war in Ilam city. This descriptive- analytic study was investigated the PTSD among the residents of Ilam city who were involved directly or indirectly in the war issues. The sample size was 5110 people chosen through cluster sampling technique. Data were analyzed through statistical methods such as K2 test, t-test, linear regression test, and variance analysis in SPSS software. The results of the study revealed that 26 of the cases who had residence background in Ilam city during Iraqi war against Iran suffered from mental disorder (PTSD). Most of these patients were married, illiterate, or primary educated people and mostly the young and middle aged housewives. The war-induced posttraumatic stress disorder has had negative effects on different aspects of Ilam city residents' health. Therefore, identifying the vulnerable groups to apply medical treatment seemed important and necessary