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System Throughput (system + throughput)
Selected AbstractsOpportunistic multiuser scheduling with reduced feedback loadEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2010Yahya S. Al-HarthiArticle first published online: 27 MAY 2010 In this paper, we propose a reduced feedback opportunistic scheduling (RFOS) algorithm that reduces the feedback load while preserving the performance of opportunistic scheduling (OS). The RFOS algorithm is a modified version of our previously proposed algorithm, the DSMUDiv algorithm. The main difference is that RFOS consists of a probing process (search process) and a requesting feedback process based on a threshold. The threshold value is variable, and it depends on the probing process. To reduce the feedback rate, a quantised value indicating the modulation level is fed back, instead of the full value of the signal-to-noise ratio (SNR), which we call quantised SNR. The paper includes the closed-form expressions of the probing load, feedback load and spectral efficiency. In addition, we investigate the effect of the scheduling delay on the system throughput (STH). Under slow Rayleigh fading assumption, we compare RFOS algorithm with the DSMUDiv and optimal (full feedback load) selective diversity scheduling algorithms. Copyright © 2010 John Wiley & Sons, Ltd. [source] DFold: PCR design that minimizes secondary structure and optimizes downstream genotyping applications,HUMAN MUTATION, Issue 1 2004David Fredman Abstract Secondary structures in polymerase chain reaction (PCR) target sequences have a negative impact on amplification success rates and on downstream uses of PCR products. For example, signal strength and allele discrimination in single nucleotide polymorphism (SNP) genotyping methods can be compromised by allele-biased amplification and/or by PCR product folding that limits access of interrogating probes. To increase the fidelity and robustness of PCR, and to aid follow-on applications, we have developed DFold (http://dfold.cgb.ki.se),a generalized software solution that creates PCR oligonucleotide primer designs devoid of stable secondary structures. We demonstrate the effectiveness of the tool by applying it to a range of dynamic allele-specific hybridization (DASH) assay designs, many of which we evaluate in the laboratory. We further consider how the system throughput may be made sufficiently high for use upon millions of target sequences in order to support whole-genome analyses. Hum Mutat 24:1,8, 2004. © 2004 Wiley-Liss, Inc. [source] Joint queue control and user scheduling in MIMO broadcast channel under zero-forcing multiplexingINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 12 2009Feng She Abstract This paper studies the problem of queue control and user scheduling in multi-antenna broadcast (downlink) systems under zero forcing beamforming transmit strategy. In the system, we assume that the data packet arrives randomly to the buffered transmitter. By taking the broadcast channel as a controlled queueing system, we deduce the property of queue control function that maximizes the weighted system throughput while guarantees the delay fairness among users. We also present a low-complexity user selection algorithm with the consideration of queue state and channel state together. Simulation results show that the joint queue control and user selection policy can achieve considerable fairness and stability among users. Copyright © 2009 John Wiley & Sons, Ltd. [source] Performance analysis of IEEE 802.11 DCF with stochastic reward nets,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2007R. Jayaparvathy Abstract In this paper, we present a performance study to evaluate the mean delay and the average system throughput of IEEE 802.11-based wireless local area networks (WLANs). We consider the distributed co-ordination function (DCF) mode of medium access control (MAC). Stochastic reward nets (SRNs) are used as a modelling formalism as it readily captures the synchronization between events in the DCF mode of access. We present a SRN-based analytical model to evaluate the mean delay and the average system throughput of the IEEE 802.11 DCF by considering an on,off traffic model and taking into account the freezing of the back-off counter due to channel capture by other stations. We also compute the mean delay suffered by a packet in the system using the SRN formulation and by modelling each station as an M/G/1 queue. We validate our analytical model by comparison with simulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Performance analysis of integrating voice and data services over PACS systems in a multicarrier environmentINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2002Jyh-Horng Wen Abstract The purpose of this paper is to study the performance of integrating voice and data services over PACS systems in a multicarrier environment. Several time-slot allocation schemes are proposed. With continuous-time Markov model, the performance can be evaluated. The results show that while using one system broadcast channel (SBC), the blocking rate of circuit mode services and system throughput are improved, at the sacrifice of increasing the blocking probability of packet mode services. Copyright © 2002 John Wiley & Sons, Ltd. [source] Trophic mass balanced models and dynamic simulations of benthic communities from La Rinconada Marine Reserve off northern Chile: network properties and multispecies harvest scenario assessmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2010Marco Ortiz Abstract 1.Mass balanced trophic models and dynamic simulations of two benthic ecological systems from La Rinconada Marine Reserve (Antofagasta Bay, SE Pacific) were constructed. 2.The scallop Argopecten purpuratus is the most important benthic resource in La Rinconada Marine Reserve, followed by the carnivorous snail Thais chocolata, and the filter-feeder bivalves Tagelus dombeii and Transennella pannosa. 3.Information on biomass, P/B ratios, catches, food spectrum, consumption, and dynamics of commercial and non-commercial species was obtained and examined using Ecopath with an Ecosim software package. 4.The bivalves A. purpuratus and T. dombeii represented the most abundant compartments in the studied subsystems. Of the carnivores, the snail T. chocolata was dominant, followed by the crabs Cancer spp. and the functional group of large epifauna. 5.The two subsystems presented similar values of system throughput. The mean trophic level of their fisheries also reached similar magnitudes (2.0), showing that the harvests in each system concentrated on secondary producers. Likewise, both subsystems presented similar A/C ratios (29.9 and 30.3), suggesting that they were immature. 6.The results obtained using mixed trophic impact (MTI) and Ecosim (increasing the fishing mortality Fi by four times) showed that only four species propagated the highest direct and indirect effects. Coincidentally, these species are the most economically important and the changes produced by the scallop A. purpuratus are noteworthy. 7.With regard to the system recovery time (SRT) estimates, only three species or functional groups presented the highest magnitudes, from highest to lowest: the sea star Luidia magallanica, the scallop A. purpuratus, and the crabs Cancer spp. 8.The topological keystone indexes of Jordán and Libralato had divergent results. According to Jordán's index, the keystone species were L. magallanica, Cancer spp., and detritus; whereas Libralato's index showed phytoplankton to be the keystone species. 9.Based on the results obtained, it is concluded that trophic mass balanced models and simulated management scenarios have considerable value for planning interventions and manipulations or for planning more sustainable management strategies in La Rinconada Marine Reserve. Copyright © 2009 John Wiley & Sons, Ltd. [source] Enhancement of throughput and fairness in 4G wireless access systems by non-orthogonal signalingBELL LABS TECHNICAL JOURNAL, Issue 4 2009Joerg Schaepperle Besides having significantly enhanced throughput, fourth generation (4G) cellular wireless access systems are expected to be cost efficient and provide sufficient performance even at the cell edge. This paper proposes a new method, called radial space-division multiple access (RDMA) for improving the system's spectral efficiency significantly and providing fairness among users without increasing the number of antennas and without requiring fast backbone communication and synchronization between base stations. The basic idea is to approach the capacity of the multi-user channel under fairness constraints by exploiting not only the angular dimension of space, as in space-division multiple access (SDMA), but also the radial dimension. Non-orthogonal signaling for simultaneous transmission of multiple signals over the same radio resource and joint detection in the receiver are used. Significant throughput gains are achieved with low complexity methods requiring only long term channel statistics and no instantaneous channel state information at the transmitter. Detailed link and first simple systemlevel simulation results in the context of the evolution of IEEE 802.16/Worldwide Interoperability for Microwave Access (WiMAX) systems towards 802.16m show that system throughput can be doubled without requiring more advanced analog hardware or increasing bandwidth or transmit power. © 2009 Alcatel-Lucent. [source] | |||||||||||||