Cluster-based cooperative subcarrier sensing using antenna diversity-based weighted data fusion

Cooperative spectrum sensing (CSS) is used in cognitive radio (CR) networks to improve the spectrum sensing performance in shadow fading environments. Moreover, clustering in CR networks is used to reduce reporting time and bandwidth overhead during CSS. Thus, cluster-based cooperative spectrum sensing (CBCSS) has manifested satisfactory spectrum sensing results in harsh environments under processing constraints. On the other hand, the antenna diversity of multiple input multiple output CR systems can be exploited to further improve the spectrum sensing performance. This paper presents the CBCSS performance in a CR network which is comprised of single- as well as multiple-antenna CR systems. We give theoretical analysis of CBCSS for orthogonal frequency division multiplexing signal sensing and propose a novel fusion scheme at the fusion center which takes into account the receiver antenna diversity of the CRs present in the network. We introduce the concept of weighted data fusion in which the sensing results of different CRs are weighted proportional to the number of receiving antennas they are equipped with. Thus, the receiver diversity is used to the advantage of improving spectrum sensing performance in a CR cluster. Simulation results show that the proposed scheme outperforms the conventional CBCSS scheme

Peak to average power ratio reduction in NC–OFDM systems

Non contiguous orthogonal frequency division multiplexing (NC-OFDM) is an efficient and adaptable multicarrier modulation scheme to be used in cognitive radio communications. However like OFDM, NC-OFDM also suffers from the main drawback of high peak to average power ratio (PAPR). In this paper PAPR has been reduced by employing three different trigonometric transforms. Discrete cosine transform (DCT), discrete sine transform (DST) and fractional fourier transform (FRFT) has been combined with conventional selected level mapping (SLM) technique to reduce the PAPR of both OFDM and NC-OFDM based systems. The method combines all the transforms with SLM in different ways. Transforms DCT, DST and FRFT have been applied before the SLM block or inside the SLM block before IFFT. Simulation results show the comparative analysis of all the transforms using SLM in case of both OFDM and NC-OFDM based systems

Cooperative subcarrier sensing using antenna diversity based weighted virtual sub clustering

The idea of cooperation and the clustering amongst cognitive radios (CRs) has recently been focus of attention of research community, owing to its potential to improve performance of spectrum sensing (SS) schemes. This focus has led to the paradigm of cluster based cooperative spectrum sensing (CBCSS). In perspective of high date rate 4th generation wireless systems, which are characterized by orthogonal frequency division multiplexing (OFDM) and spatial diversity, there is a need to devise effective SS strategies. A novel CBCSS scheme is proposed for OFDM subcarrier detection in order to enable the non-contiguous OFDM (NC-OFDM) at the physical layer of CRs for efficient utilization of spectrum holes. Proposed scheme is based on the energy detection in MIMO CR network, using equal gain combiner as diversity combining technique, hard combining (AND, OR and Majority) rule as data fusion technique and antenna diversity based weighted clustering as virtual sub clustering algorithm. Results of proposed CBCSS are compared with conventional CBCSS scheme for AND, OR and Majority data fusion rules. Moreover the effects of antenna diversity, cooperation and cooperating clusters are also discussed

Peak to average power ratio based spatial spectrum sensing for cognitive radio systems

The recent convergence of wireless standards for incorporation of spatial dimension in wireless systems has made spatial spectrum sensing based on Peak to Average Power Ratio (PAPR) of the received signal, a promising approach. This added dimension is principally exploited for stream multiplexing, user multiplexing and spatial diversity. Considering such a wireless environment for primary users, we propose an algorithm for spectrum sensing by secondary users which are also equipped with multiple antennas. The proposed spatial spectrum sensing algorithm is based on the PAPR of the spatially received signals. Simulation results show the improved performance once the information regarding spatial diversity of the primary users is incorporated in the proposed algorithm. Moreover, through simulations a better performance is achieved by using different diversity schemes and different parameters like sensing time and scanning interval

Bayesian compressive sensing framework for spectrum reconstruction in Rayleigh fading channels

Compressive sensing (CS) is a novel digital signal processing technique that has found great interest in many applications including communication theory and wireless communications. In wireless communications, CS is particularly suitable for its application in the area of spectrum sensing for cognitive radios, where the complete spectrum under observation, with many spectral holes, can be modeled as a sparse wide-band signal in the frequency domain. Considering the initial works performed to exploit the benefits of Bayesian CS in spectrum sensing, the fading characteristic of wireless communications has not been considered yet to a great extent, although it is an inherent feature for all sorts of wireless communications and it must be considered for the design of any practically viable wireless system. In this paper, we extend the Bayesian CS framework for the recovery of a sparse signal, whose nonzero coefficients follow a Rayleigh distribution. It is then demonstrated via simulations that mean square error significantly improves when appropriate prior distribution is used for the faded signal coefficients and thus, in turns, the spectrum reconstruction improves. Different parameters of the system model, e.g., sparsity level and number of measurements, are then varied to show the consistency of the results for different cases

GENETIC VARIATION IN YIELD PERFORMANCE FOR THREE YEARS IN NIGELLA SATIVA L. GERMPLASM AND ITS ASSOCIATION WITH MORPHO-PHYSIOLOGICAL TRAITS AND BIOCHEMICAL COMPOSITION

Abstract In the present study, thirty two genotypes of Nigella sativa L., germplasm were evaluated for various agriculturally important traits for 3 consecutive years along with biochemical composition. Low variance was recorded in four genotypes viz., Pk-020545, Pk-020561, Pk-020576 and Pk-020646 that indicated stability. Performance of the most of the genotypes was affected by environmental fluctuations that might be attributed to cultural practices or genetic inference. High genetic variability and heritability provide an estimate and opportunity for breeders to select the promising genotypes for specific traits. The association of oil content and fatty acid methyl esters profile (oil extracted with n-hexane) revealed that linoleic acid was significant with yield during first year. Oil content, oleic acid, linoleic acid, monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) (with n-hexane) were significant during second year. Zn was significantly associated with yield obtained in the third year traits with high significance could be exploited for further hybridization and breeding program is suggested. By employing biotechnological tools in preparation of effective and safe products can be obtained, additionally they could play important role in medicinal plants cultivation, new sources of production of bioactive secondary metabolites and other aspects of medicinal plant biochemistry

Effects of Subcapsularis Neuro Muscular Reduction (NMR) in Adhesive Capsulitis

Background: To determine the effects of Subscapularis Neuromuscular Reduction (NMR) in Adhesive Capsulitis patients on pain, Range of Motion (ROM) and Quality of life. Methods: In this randomized controlled trail patients with freezing and frozen stage of Adhesive capsulitis and limited range of movement were included. Patients were randomly divided into control (Group A) and experimental group (Group B). The patients of Group A were treated with conventional physical therapy treatment protocol and patients of group B were treated with subscapularis neuromuscular reduction along with conventional physical therapy. The patient outcome measures were assessed using numeric pain rating scale (NPRS), SPADI (shoulder pain and disability index) and ranges via goniometry. Data was analyzed by SPSS 21. Results: Both group showed significant improvement, but the end value comparison showed significant difference. NMR (Neuromuscular Reduction) on Subscapularis muscles improved the pain, ROM and Patient functional status more as compared to the conventional physical therapy group. The NPRS mean value for control group was 2.90±1.09 and mean value for experimental group was 2.05±1.10with p value of 0.021 while the mean value of SPADI for control group was33.52±9.96 and for experimental group was 26.72±8.00 with p value of 0.026. Conclusion: Treatment groups showed improvement by reducing pain, improving range of motion and functional status but neuromuscular reduction of subscapularis muscles was found to be more effective

COMPARISON OF SUSTAINED PRESSURE VS ISCHEMIC COMPRESSION ON TRIGGER POINTS IN CHRONIC MYOFACIAL PAIN MANAGEMENT

ABSTRACT OBJECTIVE: To determine the effect of different trigger points approaches in improving chronic myofascial pain. METHODS: This randomized controlled trial was conducted in Railway General Hospital, Rawalpindi, Pakistan from July-December 2016. Patients were randomly divided into two treatment groups through lottery method, in which 37 male participants who full filled the inclusion criteria (persistent pain >6 months, gradual onset of pain and impaired level of activity) were randomly allocated to sustained pressure (Group A) and ischemic compression (Group B) treated groups. Both groups received eight treatments sessions. They were evaluated at baseline and after 8th visit through Numeric Pain Rating Scale (NPRS) and Chronic Pain Acceptance Questionnaire (CPAQ). RESULTS: Within the group-A the pre and post-treatment mean for NPRS were 5.05±1.17 and 2.63±0.955 (p <0.001). Pre and post-treatment CPAQ activity engagement values were 32.00±2.42 and 41.74±2.53 (p <0.001). Pre and post-treatment CPAQ pain willingness values were 29.42±3.04 and 32.63±2.91 (p <0.001). Pre and post-treatment CPAQ sum was 61.42±3.67 and 73.84±3.64 (p 0.05). Pre and post treatment values for CPAQ sum were 64.61±2.42 and 75.72±1.12 (p<0.001). CONCLUSION: Improvement in pain relief was observed in both groups but there was no significant improvement in pain relief between ischemic compression and sustained pressure groups