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IEEE International Conference on Communications (ICC)

作者： Feng, Yuanfang Luo, Yaqiao Xu, Wenjun Li, Shengyu He, Zhiqiang Lin, Jiaru Beijing Univ Posts & Telecommun Minist Educ Key Lab Univ Wireless Commun Beijing Peoples R China

ISBN: (纸本)9781479946402

This paper investigates the energy-efficient power allocation for orthogonal frequency division multiplexing (OFDM) based relay-aided cognitive radio networks (CRNs) with imperfect spectrum sensing considered in the system model. The object is to maximize the energy efficiency measured by the "Throughput per Joule" metric subject to the total transmit power and interference constraints. To solve the problem efficiently, the primal problem is transformed into a convex optimization problem using the fractional programming method. Optimal and suboptimal algorithms are proposed, and simulation results reveal that the proposed algorithms can obtain a good tradeoff between energy and capacity. Meanwhile, the suboptimal algorithm can reduce the computational complexity hugely with a marginal performance loss compared with the optimal algorithm.

关键词： Energy efficiency Relay networks power splitting Transmitter power Orthogonal frequency division multiplexing Interference constraints Imperfect allocation algorithm Optimization algorithms algorithms Spectra

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allocation algorithms for Autonomous Management of Collaborative Cloudlets

Allocation Algorithms for Autonomous Management of Collabora...

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IEEE International Conference on Mobile Cloud Computing, Services, and Engineering

作者： Steven Bohez Tim Verbelen Pieter Simoens Bart Dhoedt Department of Information Technology Internet Based Communication Networks and Services (IBCN) Ghent University - iMinds

ISBN: (纸本)9781479944248

Mobile applications are evolving towards support for advanced interactivity and resource-demanding multimedia features. Mobile platforms are however struggling to cope with these new innovative application concepts, such as Augmented Reality, due to the inherent limitations on their available resources, such as CPU, memory and battery power. Offloading resource-intensive calculations to nearby infrastructure or devices, also known as cloudlets, has emerged as a viable alternative in offering interactive and resource-intensive applications to mobile users. This concept of resource sharing provides promising opportunities for collaborative scenarios in which not only data processing, but also the data itself are shared between multiple users. In this paper, we investigate the challenges posed by offloading collaborative mobile applications. We describe the problem of autonomous management of collaborative cloudlets and propose two heuristic algorithms, Simulated Annealing and Steepest Descent, in order to solve this optimization problem, We observe that these heuristics yield an effectiveness of more than 90% for execution times that are three orders of magnitude lower when compared to a guaranteed-optimal approach.

关键词： Resource sharing Mobile Applications CPU memory allocation algorithm moving platform UNLOADING augmented reality Heuristic algorithms Heuristics

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Improved reduced-complexity bit and power allocation algorithms for multicarrier systems

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Journal of Southeast University(English Edition) 2007年第1期23卷 12-15页

作者：许威赵春明东南大学移动通信国家重点实验室南京210096

Based on the iterative bit-filling procedure, a computationally efficient bit and power allocation algorithm is presented. The algorithm improves the conventional bit-filling algorithms by maintaining only a subset of subcarriers for computation in each iteration, which reduces the complexity without any performance degradation. Moreover, a modified algorithm with even lower complexity is developed, and equal power allocation is introduced as an initial allocation to accelerate its convergence. Simulation results show that the modified algorithm achieves a considerable complexity reduction while causing only a minor drop in performance.

关键词： multicarrier modulation allocation algorithm bit loading computational complexity

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Estimation of Distribution algorithm for green resource allocation in cognitive radio systems

Estimation of Distribution Algorithm for green resource allo...

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International Conference on Signal Processing and Communication Systems, ICSPCS

作者： Muhammad Naeem Saeed Ashrafinia Daniel Lee Department of Electrical and Computer Engineering Ryerson University Toronto ONT Canada School of Engineering Science Simon Fraser University Burnaby BC Canada

ISBN: (纸本)9781467323925

In this paper, we formulate a resource allocation optimization problem for a cooperative relay-assisted cognitive radio system, comprising a single source node, multiple relays and multiple destinations. Our formulation takes into account the effects of the resource allocation on CO 2 emission, and we refer to it as a green resource allocation problem. The green resource allocation problem is formulated as a non-linear multi-objective optimization problem. We modify the objective function by applying the weighted sum method, which results in a non-convex mixed integer non-linear programming problem. We propose a hybrid evolutionary scheme that utilizes an enhanced version of Estimation of Distributions algorithm to solve this optimization problem. Simulation results demonstrate the efficiency of our evolutionary algorithm approach in comparison to other schemes such as GA and EDA.

关键词： Estimation optimization version Resource utilization allocation algorithm Radio systems management of resources Cognitive radio green Non-Convex

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Simplified Sequential Linear Assignment algorithm for Energy Efficient Resource allocation

Simplified Sequential Linear Assignment Algorithm for Energy...

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IEEE Vehicular Technology Conference

作者： Jingon Joung Peng Hui Tan Chin Keong Ho Sumei Sun Institute for Infocomm Research (I2R) AfiSTAR I Fusionopolis Way #21-01 Connexis (South Tower) Singapore 138632 TEL: +65-6408-2000 FAX: +65-6776-1378

ISBN: (纸本)9781467309899

We consider an energy efficient resource allocation method for orthogonal frequency division multiple access (OFDMA) systems consisting of M users and N subchannels. Transmit power assignment follows the optimal strategy, i.e., a water-filling strategy, for the given subchannels. For the subchannel allocation, we introduce a recently proposed algorithm called a sequential linear assignment algorithm (SLAA). The SLAA determines how many subchannels are allocated to each user and which subchannels are allocated to each user by solving the outer and inner problems, respectively, in an iterative manner;as a result, it requires O(MN2(N ?M)2) complexity. To reduce the computational complexity of SLAA, we propose a simplified sequential linear assignment algorithm (SSLAA). Based on the observation that a user requiring the higher power would take the more subchannels, SSLAA uses each user's power consumption as a metric to determine who will take an additional subchannel in each iteration. Consequently, contrast to SLAA using network power consumption as a metric, the SSLAA incurs significant reduction of computational complexity, by OfiN2(N ?M)2). Computer simulations in compared with other existing heuristic algorithms verify that the proposed SSLAA results in high energy efficiency and low computational complexity.

关键词： OFDMA energy efficiency resource allocation linear assignment algorithm subchannel Resource utilization complexity classes allocation algorithm Consumers OFDMA Energy efficiency Power consumption high energy efficiency Orthogonal frequency division multiplexing optimal strategy management of resources

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Optimality and greed in dynamic allocation

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JOURNAL OF algorithmS-COGNITION INFORMATICS AND LOGIC 2001年第2期41卷 244-261页

作者： Winkler, P Bell Labs Murray Hill NJ 07974 USA

In dynamic allocation items arrive and depart randomly and while present are stored in a limited facility;the job of an allocation algorithm is to decide whether and where to store an arriving item, while trying to minimize the cost incurred by rejections. Ordinarily, to prove the value of such an algorithm, one must either assume a specific arrival distribution (e.g., Poisson-lambda), or try to obtain bounds relative to an adversary (as in competitive analysis). We present here a novel method of proving precise optimality for certain kinds of dynamic allocation algorithms, without assuming a specific arrival distribution. We do need to assume memoryless departure for at least some item types, and most importantly, we must assume conditions are such that it is not right to reject arrivals unnecessarily. The method is applied to two simple call assignment problems which arose, in quite different circumstances, at Lucent Technologies. In both cases the method was successful in showing that the intuitively best assignment algorithm really does minimize expected cost under fairly general, and essentially necessary, assumptions. (C) 2001 Elsevier Science.

关键词： dynamic allocation Rejection (Psychology) greedy method allocation algorithm optimality

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Disk Cluster allocation Behavior in Windows and NTFS

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MOBILE NETWORKS & APPLICATIONS 2020年第1期25卷 248-258页

作者： Karresand, Martin Axelsson, Stefan Dyrkolbotn, Geir Olav Norwegian Univ Sci Dept Informat Secur Commun Technol Technol Gjovik Norway Div Command ControlCommunicatComputersIntelligence SurveillanceReconnaissanceSwedish Def Res Agcy Linkoping Sweden Halmstad Univ Sch Informat Technol Halmstad Sweden

The allocation algorithm of a file system has a huge impact on almost all aspects of digital forensics, because it determines where data is placed on storage media. Yet there is only basic information available on the allocation algorithm of the currently most widely spread file system;NTFS. We have therefore studied the NTFS allocation algorithm and its behavior empirically. To do that we used two virtual machines running Windows 7 and 10 on NTFS formatted fixed size virtual hard disks, the first being 64 GiB and the latter 1 TiB in size. Files of different sizes were written to disk using two writing strategies and the $Bitmap files were manipulated to emulate file system fragmentation. Our results show that files written as one large block are allocated areas of decreasing size when the files are fragmented. The decrease in size is seen not only within files, but also between them. Hence a file having smaller fragments than another file is written after the file having larger fragments. We also found that a file written as a stream gets the opposite allocation behavior, i. e. its fragments are increasing in size as the file is written. The first allocated unit of a stream written file is always very small and hence easy to identify. The results of the experiment are of importance to the digital forensics field and will help improve the efficiency of for example file carving and timestamp verification.

关键词： Digital forensics File carving allocation algorithm NTFS

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Dynamic resource allocation with precoding and joint coding scheme for limited feedback-based wireless multi-antenna multicast system

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IET COMMUNICATIONS 2013年第5期7卷 397-407页

作者： Chen, Lei Wang, Xiaoxiang He, Gaoning Beijing Univ Posts & Telecommun Minist Educ Key Lab Universal Wireless Commun Beijing 100876 Peoples R China Shenyang Agr Univ Sch Infarmat Engn Dept Commun Engn Shenyang 110044 Peoples R China Cent Res Inst Hua Wei Shanghai 200233 Peoples R China

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, the authors introduce a resource allocation algorithm by exploiting layered coding combined with erasure correction coding for multicast services in the downlink of orthogonal frequency-division multiple access-based multi-antenna system. To reduce the feedback overhead of uplink, the authors design a novel transmission scheme with limited feedback. Then, the joint subcarrier and power allocation problem for the data of base layer and enhancement layers are formulated, which is shown to be non-deterministic polynomial-hard. Hence, in order to reduce the computational complexity, they propose a three-phase suboptimal algorithm. The algorithm is designed to maximise the system throughput, whereas at the same time guarantee the quality of services (QoS) requirements of all multicast groups. It is composed of precoding scheme, proportional fairness subcarrier allocation algorithm and modified water-filling power allocation algorithm with QoS guarantees (MWF-Q). To further decrease the complexity of MWF-Q, a power allocation algorithm with increased fixed power allocation algorithm with QoS guarantees is introduced. Simulation results show that the proposed algorithms based on limited feedback scheme significantly outperform CMS and any other existing algorithm with full feedback. Moreover, the proposed scheme can efficiently reduce 50% of the full feedback overhead.

关键词： Quality of service BASE COURSE allocation algorithm Feedback Meltdown Resource utilization management of resources prediction coding Multicast multiple antenna power splitting

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Using NTFS Cluster allocation Behavior to Find the Location of User Data

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DIGITAL INVESTIGATION 2019年 29卷 S51-S60页

作者： Karresand, Martin Axelsson, Stefan Dyrkolbotn, Geir Olav Norwegian Univ Sci & Technol NTNU Dept Informat Secur & Commun Technol IIK Trondheim Norway Swedish Def Res Agcy FOI Div Command Control Commun Comp Intelligence Surv Stockholm Sweden Halmstad Univ Halmstad Sweden

Digital forensics is heavily affected by the large and increasing amount of data to be processed. To solve the problem there is ongoing research to find more efficient carving algorithms, use parallel processing in the cloud, and reduce the amount of data by filtering uninteresting files. Our approach builds on the principle of searching where it is more probable to find what you are looking for. We therefore have empirically studied the behavior of the cluster allocation algorithm(s) in the New Technology File System (NTFS) to see where new data is actually placed on disk. The experiment consisted of randomly writing, increasing, reducing and deleting files in 32 newly installed Windows 7, 8, 8.1 and 10 virtual computers using VirtualBox. The result show that data are (as expected) more frequently allocated closer to the middle of the disk. Hence that area should be getting higher attention during a digital forensic investigation of a NTFS formatted hard disk. Knowledge of the probable position of user data can be used by a forensic investigator to prioritize relevant areas in storage media, without the need for a working file system. It can also be used to increase the efficiency of hash-based carving by dynamically changing the sampling frequency. Our findings also contributes to the digital forensics processes in general, which can now be focused on the interesting regions on storage devices, increasing the probability of getting relevant results faster. (C) 2019 The Author(s). Published by Elsevier Ltd on behalf of DFRWS.

关键词： Digital forensics File carving Partition content map allocation algorithm NTFS

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An Empirical Study of the NTFS Cluster allocation Behavior Over Time

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FORENSIC SCIENCE INTERNATIONAL-DIGITAL INVESTIGATION 2020年 33卷

作者： Karresand, Martin Dyrkolbotn, Geir Olav Axelsson, Stefan Norwegian Univ Sci & Technol NTNU Trondheim Norway Swedish Def Res Agcy FOI Stockholm Sweden Norwegian Def Cyber Acad NDCA Oslo Norway Halmstad Univ Halmstad Sweden

The amount of data to be handled in digital forensic investigations is continuously increasing, while the tools and processes used are not developed accordingly. This especially affects the digital forensic subfield of file carving. The use of the structuring of stored data induced by the allocation algorithm to increase the efficiency of the forensic process has been independently suggested by Casey and us. Building on that idea we have set up an experiment to study the allocation algorithm of NTFS and its behavior over time from different points of view. This includes if the allocation algorithm behaves the same regardless of Windows version or size of the hard drive, its adherence to the best fit allocation strategy and the distribution of the allocation activity over the available (logical) storage space. Our results show that space is not a factor, but there are differences in the allocation behavior between Windows 7 and Windows 10. The results also show that the allocation strategy favors filling in holes in the already written area instead of claiming the unused space at the end of a partition and that the area with the highest allocation activity is slowly progressing from approximately 10 GiB into a partition towards the end as the disk is filling up. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of DFRWS. All rights reserved.

关键词： Digital forensics File carving Cluster allocation pattern allocation algorithm NTFS

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