Impact of Adaptive Modulation and Coding Schemes on Bit Error Rate for System Performance in the Uplink LTE System

Long Term Evolution (LTE) is a cellular network technology aims to render enriched data services to users at lower latency and higher (multi-megabit) throughput. The higher system throughput with more reliable transmission is achieved by the support of Adaptive Modulation and Coding (AMC) schemes, scheduling algorithms, multi-antenna techniques etc. The AMC schemes substantially increases the system throughput by reducing the Bit Error Rates (BER) and by adjusting the transmission parameters based on the link quality. The scheduling algorithms also enhance the throughput of individual users, as well as the cell throughput by allocating the resources among the active users. Hence in this paper, an attempt has been made to study and evaluate the effects of AMC schemes such as QPSK, 16-QAM and 64-QAM on uplink LTE system performance for Proportional Fair (PF) and Round Robin (RR) scheduling algorithms using QualNet 7.1 network simulator. The performance metrics considered for the simulation studies are BER, cell throughput, average delay and average jitte

Effect of Bandwidth Scalability on System Performance in the Downlink LTE Systems

Long Term Evolution (LTE) system employs Orthogonal Frequency Division Multiple Access (OFDMA) in downlink in order to support network deployment using various system bandwidth configurations i.e., 1.4MHz, 3MHZ, 5MHz, 10MHz, 15MHz and 20MHz. The bandwidth scalability enables operator to access multiple channels to achieve higher peak data rates. Also, the bandwidth scalability allows operators to deploy LTE network with the existing spectrum or newly licensed band. Therefore the study on performance of LTE system with different bandwidth configuration becomes vital. Hence in this paper, an attempt has been made to study and compare the performance of LTE system with different spectrum configuration i.e., 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz and 20MHz for Constant Bit Rate (CBR) traffic scenario in the downlink. The performance metrics considered for simulation studies are aggregate bytes received, average throughput, average delay and average jitter

Li2SnO3 as a Cathode Material for Lithium-ion Batteries:Defects, Lithium Ion Diffusion and Dopants

Tin-based oxide Li2SnO3 has attracted considerable interest as a promising cathode material for potential use in rechargeable lithium batteries due to its high- capacity. Static atomistic scale simulations are employed to provide insights into the defect chemistry, doping behaviour and lithium diffusion paths in Li2SnO3. The most favourable intrinsic defect type is Li Frenkel (0.75 eV/defect). The formation of anti-site defect, in which Li and Sn ions exchange their positions is 0.78 eV/defect, very close to the Li Frenkel. The present calculations confirm the cation intermixing found experimentally in Li2SnO3. Long range lithium diffusion paths via vacancy mechanisms were examined and it is confirmed that the lowest activation energy migration path is along the c-axis plane with the overall activation energy of 0.61 eV. Subvalent doping by Al on the Sn site is energetically favourable and is proposed to be an efficient way to increase the Li content in Li2SnO3. The electronic structure calculations show that the introduction of Al will not introduce levels in the band gap

A Neuron-Glial Perspective for Computational Neuroscience

International audienceThere is growing excitement around glial cells, as compelling evidence point to new, previously unimaginable roles for these cells in information processing of the brain, with the potential to affect behavior and higher cognitive functions. Among their many possible functions, glial cells could be involved in practically every aspect of the brain physiology in health and disease. As a result, many investigators in the field welcome the notion of a Neuron-Glial paradigm of brain function, as opposed to Ramon y Cayal's more classical neuronal doctrine which identifies neurons as the prominent, if not the only, cells capable of a signaling role in the brain. The demonstration of a brain-wide Neuron-Glial paradigm however remains elusive and so does the notion of what neuron-glial interactions could be functionally relevant for the brain computational tasks. In this perspective, we present a selection of arguments inspired by available experimental and modeling studies with the aim to provide a biophysical and conceptual platform to computational neuroscience no longer as a mere prerogative of neuronal signaling but rather as the outcome of a complex interaction between neurons and glial cells

A Bandwidth Request Mechanism for QoS Enhancement in Mobile WiMAX Networks

The IEEE 802.16e standard is designed to support high bandwidth for the mobile wireless metropolitan area network. In order to support Quality of Service (QoS) for multimedia applications, various bandwidth request and scheduling mechanisms are suggested in WiMAX, in which a subscriber station (SS) sends bandwidth request messages to a base station (BS) and the BS grants the bandwidth according to the available radio resources. In this paper a bandwidth request mechanism for ertPS, rtPS and nrtPS is proposed to enhance the QoS performance of WiMAX network. In the proposed bandwidth request mechanism, the SS requests for the additional bandwidth for the service flows by considering the round trip delay incurred during the bandwidth request grant process. The performance of proposed bandwidth request mechanism is evaluated through simulation by considering the metrics like throughput and delay