98 research outputs found

    A Two-Phase Power Allocation Scheme for CRNs Employing NOMA

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    In this paper, we consider the power allocation (PA) problem in cognitive radio networks (CRNs) employing nonorthogonal multiple access (NOMA) technique. Specifically, we aim to maximize the number of admitted secondary users (SUs) and their throughput, without violating the interference tolerance threshold of the primary users (PUs). This problem is divided into a two-phase PA process: a) maximizing the number of admitted SUs; b) maximizing the minimum throughput among the admitted SUs. To address the first phase, we apply a sequential and iterative PA algorithm, which fully exploits the characteristics of the NOMA-based system. Following this, the second phase is shown to be quasiconvex and is optimally solved via the bisection method. Furthermore, we prove the existence of a unique solution for the second phase and propose another PA algorithm, which is also optimal and significantly reduces the complexity in contrast with the bisection method. Simulation results verify the effectiveness of the proposed two-phase PA scheme

    Capacity Comparison between MIMO-NOMA and MIMO-OMA with Multiple Users in a Cluster

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    In this paper, the performance of multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) is investigated when multiple users are grouped into a cluster. The superiority of MIMO-NOMA over MIMO orthogonal multiple access (MIMO-OMA) in terms of both sum channel capacity and ergodic sum capacity is proved analytically. Furthermore, it is demonstrated that the more users are admitted to a cluster, the lower is the achieved sum rate, which illustrates the tradeoff between the sum rate and maximum number of admitted users. On this basis, a user admission scheme is proposed, which is optimal in terms of both sum rate and number of admitted users when the signal-to-interference-plus-noise ratio thresholds of the users are equal. When these thresholds are different, the proposed scheme still achieves good performance in balancing both criteria. Moreover, under certain conditions,it maximizes the number of admitted users. In addition, the complexity of the proposed scheme is linear to the number of users per cluster. Simulation results verify the superiority of MIMO-NOMA over MIMO-OMA in terms of both sum rate and user fairness, as well as the effectiveness of the proposed user admission scheme.Comment: accepted IEEE Journal on Selected Topics in Communications, June 2017, Keywords: Non-orthogonal multiple access (NOMA), multiple-input multiple-output (MIMO), channel capacity, sum rate, fairness, user admission, power allocatio

    Національномовна специфіка категоризації світу

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    У статті реалізовано системний підхід до вивчення національної специфіки мовної категоризації світу, який передбачає розгляд одиниць мови, передусім слова, у його зв’язку з реаліями життя народу, його історією, культурою, географічними умовами проживання, особливостями світосприйняття, менталітету, життєвим досвідом. З цією метою до аналізу семантики слів на позначення особи за місцем її проживання, крім дефініцій тлумачних словників української мови, залучено відомості з аспектних лінгвістичних словників (синонімів, антонімів) та спеціальних етнолінгвістичних і лінгвокультурологічних джерел. Окрему увагу приділено методам виявлення етноконотацій в ідеографічній параметризації української лексики.The article deals with the system approach to studying national language specificities that provides examination of a word in interrelation with life realities, history, culture, geographical conditions, features of world view, national mentality, life experience reflected in language. Such work demanded, except for the analysis of definitions of available explanatory dictionaries, attraction of data from aspect dictionaries (synonyms, antonyms) and special ethno linguistic and linguistic cultural source. The research has been carried on the basis of nouns-names of person according to the residence. The significant attention is given to the methods of research national language specificities of the world’s categorization

    Microscale Discrete Element Method Simulation of the Carbon Black Aggregate Fracture Behavior in a Simple Shear Flow

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    The shear stress induced breaking behavior of carbon black (CB) aggregates during the manufacturing process of Li‐ion batteries is investigated via microscale discrete element method (DEM) simulations. The relevant range of shear stress is chosen according to a planetary mixer and cathode slurries with high solid content. Aggregates of different sizes and shapes are modeled using a self‐written algorithm based on the tunable dimension method. Then, suitable models are chosen for representing the solid bridges between the primary particles of the CB aggregates and relevant fluid forces. The results show a correlation between aggregate size and critical shear stress which is required to initiate aggregate fracturing. Furthermore, a change in aggregate shape is linked to applied stress and initial aggregate size and shape. Hence, a recommendation for an efficient disintegration of CB aggregates during the mixing process is made

    Somatosensory phenomena elicited by electrical stimulation of hippocampus: Insight into the ictal network.

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    Up to 11% of patients with mesial temporal lobe epilepsy experience somatosensory auras, although these structures do not have any somatosensory physiological representation. We present the case of a patient with left mesial temporal lobe epilepsy who had somatosensory auras on the right side of the body. Stereo-EEG recording demonstrated seizure onset in the left mesial temporal structures, with propagation to the sensory cortices, when the patient experienced the somatosensory aura. Direct electrical stimulation of both the left amygdala and the hippocampus elicited the patient's habitual, somatosensory aura, with afterdischarges propagating to sensory cortices. These unusual responses to cortical stimulation suggest that in patients with epilepsy, aberrant neural networks are established, which have an essential role in ictogenesis

    Bandwidth allocation in cooperative wireless networks: Buffer load analysis and fairness evaluation.

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    In modern cooperative wireless networks, the resource allocation is an issue of major significance. The cooperation of source and relay nodes in wireless networks towards improved performance and robustness requires the application of an efficient bandwidth sharing policy. Moreover, user requirements for multimedia content over wireless links necessitate the support of advanced Quality of Service (QoS) features. In this paper, a novel bandwidth allocation technique for cooperative wireless networks is proposed, which is able to satisfy the increased QoS requirements of network users taking into account both traffic priority and packet buffer load. The performance of the proposed scheme is examined by analyzing the impact of buffer load on bandwidth allocation. Moreover, fairness performance in resource sharing is also studied. The results obtained for the cooperative network scenario employed, are validated by simulations. Evidently, the improved performance achieved by the proposed technique indicates that it can be employed for efficient traffic differentiation. The flexible design architecture of the proposed technique indicates its capability to be integrated into Medium Access Control (MAC) protocols for cooperative wireless networks

    Leaching behaviour of pendimethalin causes toxicity towards different cultivars of Brassica juncea and Brassica campestris in sandy loam soil

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    An experiment was conducted at the farm of Zonal Adaptive Research Station, Uttar Banga Krishi Viswavidhyalaya, Pundibari, Cooch Behar, West Bengal to evaluate the effect of pendimethalin on the yield, weed density and phytotoxicity in different varieties of rai (Brassica juncea) and yellow sarson (B. campestris var. yellow sarson) under higher soil moisture regime in Terai region of West Bengal. Pre-emergence application of pendimethalin at higher dose i.e. 1.0 kg/ha recorded higher plant mortality (30.92%) due to the presence of higher concentration of pendimethalin residue (0.292 µg/g) till the tenth day of crop age and consequently had the reduced yield (12.59 q/ha) than the dose of 0.7 kg/ha (13.33 q/ha) where plant mortality was only 12.62% due to comparatively lower level of pendimethalin residue (0.192 µg/g). Although the application of pendimethalin at the rate of 1.0 kg/ha was able to control weed more efficiently (18.96/m2) than the dose of 0.7 kg/ha (30.41/m2) and subsequent lower doses. The herbicide leached down to the root zone resulting in phytotoxicity towards crop. Yellow sarson group (Brassica campestris) showed more susceptibility than rai (Brassica juncea) group against pendimethalin application at higher doses
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