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Existing Schemes (existing + scheme)

Distribution by Scientific Domains

Information Science and Computing	50%

Selected Abstracts

Joint power, subcarrier and subframe allocation in Multihop relay networks

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2009
Tolga Girici
Abstract In this paper we study the problem of subframe, subchannel and power allocation in OFDMA-based multihop relay networks. The system consists of a base station (BS), a number of relay stations (RS) and mobile stations (MS). We consider frame by frame scheduling, where the frame is divided into two subframes such as BS-RS and RS-MS subframes. We study two different problems, satisfying link rate requirements with minimum-weighted total power and maximizing proportional fairness. For the first problem, we find the optimal solution and also propose a less complex subframe and bandwidth allocation scheme with good performance. For the second problem, we propose an algorithm that outperforms an existing scheme with less feedback. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Reducing signaling traffic in wireless ATM networks through handoff scheme improvement

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2002
Professor Anna Ha
We propose a new handoff call management scheme which reduces signaling traffic in wireless ATM networks and improves the efficiency of the virtual channel. Chaining followed by a make-break algorithm is a suitable handoff scheme for various situations. In the chaining part of the scheme, a chain routing algorithm is studied and compared with the hop-limiting scheme. When the algorithm is implemented in our scheme, it improves the performance of the existing scheme in call drop rates so as to reduce the signaling traffic in wireless ATM networks. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Distributed loop-scheduling schemes for heterogeneous computer systems

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 7 2006
Anthony T. Chronopoulos
Abstract Distributed computing systems are a viable and less expensive alternative to parallel computers. However, a serious difficulty in concurrent programming of a distributed system is how to deal with scheduling and load balancing of such a system which may consist of heterogeneous computers. Some distributed scheduling schemes suitable for parallel loops with independent iterations on heterogeneous computer clusters have been designed in the past. In this work we study self-scheduling schemes for parallel loops with independent iterations which have been applied to multiprocessor systems in the past. We extend one important scheme of this type to a distributed version suitable for heterogeneous distributed systems. We implement our new scheme on a network of computers and make performance comparisons with other existing schemes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Performance analysis of a channel allocation scheme for multi-service mobile cellular networks

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2007
Shensheng Tang
Abstract This paper presents a new channel allocation scheme, namely the dynamic partition with pre-emptive priority (DPPP) scheme, for multi-service mobile cellular networks. The system is modelled by a two-dimensional Markov process and analysed by the matrix-analytic method. A pre-emptive priority (PP) mechanism is employed to guarantee the quality of service (QoS) requirement of the real-time (RT) traffic at the expense of some degradation of non-real-time (NRT) traffic, while the victim buffer compensates the degradation and has no negative impact on the RT traffic. The complete service differentiation between new calls and handoff calls from different traffic classes is achieved by using the dynamic partition (DP) concept with the help of related design parameters. The performance analysis and numerical results show that the DPPP scheme, compared with the existing schemes, is effective and practical in multi-service environments. Copyright © 2006 John Wiley & Sons, Ltd. [source]

A novel methodology for robust VBR video transmission in an ATM system

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2002
A. Alheraish
A dynamic FEC (DFEC) scheme for VBR video in ATM networks is proposed. The scheme combines the design of source encoder, error control, and the network. In the design, we will develop a methodology to vary FEC redundancy dynamically. The methodology considers the fluctuations in video source and network utilisation to adjust the FEC redundancy levels. We demonstrate the effectiveness of the proposed scheme by examining its performance with three existing schemes in terms of loss rates, throughput, and quality degradation. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Accounting for unresolved clouds in a 1-D solar radiative-transfer model

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 608 2005
J. Li
Abstract New methods for the treatment of solar radiative transfer through overlapping and inhomogeneous clouds are presented. First, a new approach to cloud overlap is shown. For the adjacent cloud blocks, the traditional maximum overlap can be relaxed to a mixture of maximum and random overlap treatments for layers that are adjacent but not fully correlated. Second, a new radiative-transfer algorithm has been developed to deal with these various cloud overlap circumstances that is simple enough for implementation in a general-circulation model (GCM). When compared to appropriate benchmark calculations, we find that this new method can produce accurate results in heating rates and fluxes with relative errors generally less than 8%. Third, a new and very simple approach to treating radiative transfer through a cloud with horizontal subgrid-scale inhomogeneities is developed. This approach uses an optical-depth scaling technique to represent the subgrid-scale inhomogeneity. Finally, by combining all of the above elements, we provide a new algorithm for the combined treatment of cloud overlap and inhomogeneity and we show that it yields very reasonable accuracies for heating rates and fluxes. Through benchmark comparisons, we show that this new algorithm provides significant improvement over existing schemes in GCMs. Copyright © 2005 Royal Meteorological Society [source]