Access Bandwidth Research Articles

A Cooperative Incentive Structure for Mobile Cloud Computing

Encouraging the mobile devices to contribute their idle resources is critical to promote the quality of service of Mobile Cloud Computing (MCC), especially when the remote cloud service is absent or the access bandwidth is limited. In order to achieve this goal, a carefully devised MCC architecture with appreciate incentive mechanismis needed. In this paper, inthe view point of cooperative game, an incentive structure based on Shapley Value is brought forward for Hybrid Local Mobile Cloud Model-with stabilityanalysis. Moreover, the implementation issues of the incentive structure and its experimental evaluation are presented.

Consistent data sharing in mobile ad hoc networks

In Mobile Adhoc Networks MANETs, data availability is lower in comparison to the conventional fixed networks because of their mobility and resource-constrained characteristics. Replication and caching have been adapted to improve the performance in these constrained environments. These techniques significantly improve the efficiency of information access in MANETs resulting in reduction of the access latency and bandwidth usage. The paper proposes a cluster-based caching and data consistency algorithm where the clustering is done employing learning automata to support stability. The caching related information is maintained by the clusters members and the cluster heads. Apart from the avoidance of cached data redundancy and the reduction in the average access latency, the proposed scheme also enables TTL-based cache invalidation to avoid the stale data availability. The network is simulated using NS-2 to evaluate the performance of the proposed algorithm. The simulation results show an improvement in the cache hit ratio and reduction in average latency compared with few existing caching schemes.

Data replication strategies with performance objective in data grid systems: a survey

Replicating for performance constitutes an important issue in large-scale data management systems. In this context, a significant number of replication strategies have been proposed for data grid systems. Some works classified these strategies into static vs. dynamic or centralised vs. decentralised or client vs. server initiated strategies. Very few works deal with a replication strategy classification based on the role of these strategies when building a replica management system. In this paper, we propose a new replication strategy classification based on objective functions of these strategies. Also, each replication strategy is designed according to the data grid topology for which it was proposed. We point out the impact of the topology on replication performance although most of these strategies have been proposed for a hierarchical grid topology. We also study the impact of some factors on performance of these strategies, e.g. access pattern, bandwidth consumption and storage capacity.

Distributed Algorithms for a Replication Problem of Popular Network Data

The replication of popular data objects can effectively reduce the access time and bandwidth requirements of network services. We study the replication problem in the model of distributed replication groups and propose two distributed algorithms: an approximation optimal replication algorithm, which is an asynchronous distributed algorithm as it takes more time to be completed. However its performance approaches the optimal algorithm, and a fast replication algorithm that is very suitable as the initial algorithm of the approximation optimal algorithm. We give a proof of the complexity of the algorithms, and show that the time and communication complexities of the algorithms are polynomial with respect to the number of objects and the maximum storage capacities of the servers. Finally, simulation experiments are performed to investigate the performance of the algorithms, and the results show that the two algorithms can effectively solve the replication problem.

Low complexity and efficient dynamic spectrum learning and tunable bandwidth access for heterogeneous decentralized cognitive radio networks

This paper deals with the design of the low complexity and efficient dynamic spectrum learning and access (DSLA) scheme for next-generation heterogeneous decentralized Cognitive Radio Networks (CRNs) such as Long Term Evolution-Advanced and 5G. Existing DSLA schemes for decentralized CRNs are focused predominantly on the decision making policies which perform the task of orthogonalization of secondary users to optimum vacant subbands of fixed bandwidth. The focus of this paper is the design of DSLA scheme for decentralized CRNs to support the tunable vacant bandwidth requirements of the secondary users while minimizing the computationally intensive subband switchings. We first propose a new low complexity VDF which is designed by modifying second order frequency transformation and subsequently combining it with the interpolation technique. It is referred to as Interpolation and Modified Frequency Transformation based VDF (IMFT-VDF) and it provides tunable bandpass responses anywhere over Nyquist band with complete control over the bandwidth as well as the center frequency. Second, we propose a tunable decision making policy, ρt_rand, consisting of learning and access unit, and is designed to take full advantage of exclusive frequency response control offered by IMFT-VDF. The simulation results verify the superiority of the proposed DSLA scheme over the existing DSLA schemes while complexity comparisons indicate total gate count savings from 11% to as high as 87% over various existing schemes. Also, lower number of subband switchings make the proposed scheme power-efficient and suitable for battery-operated cognitive radio terminals.

SPGrid

We introduce a new method for fluid simulation on high-resolution adaptive grids which rivals the throughput and parallelism potential of methods based on uniform grids. Our enabling contribution is SPGrid , a new data structure for compact storage and efficient stream processing of sparsely populated uniform Cartesian grids. SPGrid leverages the extensive hardware acceleration mechanisms inherent in the x86 Virtual Memory Management system to deliver sequential and stencil access bandwidth comparable to dense uniform grids. Second, we eschew tree-based adaptive data structures in favor of storing simulation variables in a pyramid of sparsely populated uniform grids, thus avoiding the cost of indirect memory access associated with pointer-based representations. We show how the costliest algorithmic kernels of fluid simulation can be implemented as a composition of two kernel types: (a) stencil operations on a single sparse uniform grid, and (b) structured data transfers between adjacent levels of resolution, even when modeling non-graded octrees. Finally, we demonstrate an adaptive multigrid-preconditioned Conjugate Gradient solver that achieves resolution-independent convergence rates while admitting a lightweight implementation with a modest memory footprint. Our method is complemented by a new interpolation scheme that reduces dissipative effects and simplifies dynamic grid adaptation. We demonstrate the efficacy of our method in end-to-end simulations of smoke flow.

Performance improvement for applying network virtualization in fiber-wireless (FiWi) access networks

Fiber-wireless (FiWi) access networks, which are a combination of fiber networks and wireless networks, have the advantages of both networks, such as high bandwidth, high security, low cost, and flexible access. However, with the increasing need for bandwidth and types of service from users, FiWi networks are still relatively incapable and ossified. To alleviate bandwidth tension and facilitate new service deployment, we attempt to apply network virtualization in FiWi networks, in which the network’s control plane and data plane are separated from each other. Based on a previously proposed hierarchical model and service model for FiWi network virtualization, the process of service implementation is described. The performances of the FiWi access networks applying network virtualization are analyzed in detail, including bandwidth for links, throughput for nodes, and multipath flow transmission. Simulation results show that the FiWi network with virtualization is superior to that without.

Map cache management using dual granularity for mobile storage systems

NAND flash memories have been used in many mobile consumer devices as storage media because they are small, fast, shock-resistant, and energy-efficient. However, the flash storage systems based on these flash devices need a special software layer, the FTL, to translate logical addresses from a host system to physical addresses in NAND flash memories. Recently, the flash storage systems in mobile devices tend to employ a page-level mapping scheme as they are required to yield higher access bandwidth. Unlike common SSDs, which often keep the majority of mapping information in fast but volatile DRAM, the flash storage systems in mobile consumer devices keep only a limited subset of mapping information in a small-sized SRAM due to the restrictions in size, cost, and power consumption. For this reason, many cache management schemes proposed for SSDs may not be suitable for the flash storage systems in mobile consumer devices, though most map cache management schemes used in mobile storage are basically designed for SSD. This paper proposes a novel cache management scheme targeting mobile consumer devices. The proposed scheme uses different management granularities in allocating and evacuating cache space. Experimental results show that the proposed scheme improves map cache performance by up to 36% compared to the existing cache management techniques.

Оптимізація розподілення навантаження на бездротову мережу в офісній інфраструктурі компанії

This paper discusses methods for optimizing distribution of the load on the wireless networking in office complexes. There are three basic criteria by which to conduct optimization and prompted them to combine into a single system. These criteria are limiting bandwidth access points, creating seamless roaming zones and consideration of working hours of employees and other customers of the institution. It is shown that the latter criterion imposes appropriate restrictions on the two previous ones. Also take into account the analysis of spatial data access points are used by employees during the time of observation.Integrated optimization becomes possible through the use of statistical data obtained through observation over a short period of time from a few weeks to a month at the appropriate points of access to their workload and provide priority access to certain groups of customers in the network.

Access Point Density and Bandwidth Partitioning in Ultra Dense Wireless Networks

This paper examines the impact of system parameters such as access point density and bandwidth partitioning on the performance of randomly deployed, interference-limited, dense wireless networks. While much progress has been achieved in analyzing randomly deployed networks via tools from stochastic geometry, most existing works either assume a very large user density compared to that of access points, which does not hold in a dense network, and/or consider only the user signal-to-interference-ratio as the system figure of merit, which provides only partial insight on user rate as the effect of multiple access is ignored. In this paper, the user rate distribution is obtained analytically, taking into account the effects of multiple access as well as the SIR outage. It is shown that user rate outage probability is dependent on the number of bandwidth partitions (subchannels) and the way they are utilized by the multiple access scheme. The optimal number of partitions is lower bounded for the case of large access point density. In addition, an upper bound of the minimum access point density required to provide an asymptotically small rate outage probability is provided in closed form.

Improving Hit Ratio and Byte Hit Ratio Using Combined Pre-Fetching and Web Caching

Combined caching and pre-fetching of web pages help to enhance bandwidth utilization, reduce access delay and also reduce the load on the server. Pre-fetching is the technique of fetching Web pages in advance that will be assumed to be needed or browsed in near future by the user and the caching process stores them in the memory. In the literature, number of works has been reported separately for caching and pre-fetching of Web pages. In this paper clustering based pre-fetching technique is combined with machine learning technique-SVM (Support Vector Machine)-LRU algorithm for Web proxy caching. With the help of real dataset it is demonstrated that the latter approach will be better than Clustering based pre-fetching technique with traditional caching policy like LRU in terms of bandwidth utilization and access latency.

Network pricing: can both ISP and P2P benefit?

SummaryInternet service providers are facing increasing back pressure from rising access demand by users, especially peer‐to‐peer (P2P)‐based applications that greatly enhance the large‐scale distribution of content into and out of their networks. With the ever increasing consumption pressure on scarce bandwidth resources, ISPs have been forced to reconsider their business model of overselling ‘all‐you‐can‐eat’ broadband at flat rates. Technical solutions such as traffic differentiation or blocking violate the principle of network neutrality; traffic shaping and deep packet analysis fall short in the presence of encryption; and P4P (localized P2P)‐based solutions are difficult to achieve in a heterogeneous environment. Economically, various usage‐based pricing schemes have been proposed and discussed. While they can improve efficiency in bandwidth consumption, they tend to face strong customer resistance as users have strong preference in favour of simple flat rates. We argue that any feasible pricing reforms cannot deviate much from the current flat rates while providing financial incentives for bandwidth hogs to limit their bandwidth access. In contrast to normal usage‐based pricing models that charge by volume, we propose a temporal‐based pricing model that may generate a mutually beneficial solution that can not only increase the profitability of ISPs but also accommodate P2P, rather than killing it, without changing the software, protocols or hardware that clients or ISPs use on the network.Copyright © 2014 John Wiley & Sons, Ltd

Quality‐based charging solutions for wireless multimedia services

SUMMARYThe evolution of mobile telecommunication networks and access bandwidth has enabled operators to deliver IPTV services for mobile customers; however, the existing mobile charging solutions are not effectively addressing the billing requirements of multimedia streams. This paper develops a quality‐based charging solution for 3GPP wireless networks with the aim of providing a fair pricing solution for multimedia services. An appropriate business model is selected and a streaming proxy‐based charging architecture is developed based on the quality of the multimedia service. The proposed algorithms are theoretically evaluated by the derivation of the formulas of the distribution and the expected value of the price discount. A testbed is built and the findings are evaluated and compared with traditional charging functions. Copyright © 2014 John Wiley & Sons, Ltd.

Monitoring dan Analisis Trafik di Jaringan USM Menggunakan Multi Router Traffic Grapher

Faculty of Information and Communication Technology (FTIK) USM is one of the faculty are experiencing rapid development both of the number of students and the amount of infrastructure. FTIK occupying the building M and Q as lectures and laboratory building for student. FTIK is growth oriented faculty of Information Technology, of the entire student FTIK and academic staff need internet access to support existing teaching and learning process. When the researchers were in building M and Q, Our will compete for free internet access is provided USM because the bandwidth is allocated evenly to rent USM. The fact that there are today, when researchers were on the 2nd floor of building A, as home base for the Faculty of Agricultural Technology, researchers gain access internet very easily. This is contrary to the conditions in the building M and Q, whereas the number of students in the Faculty of Agricultural Technology , not as much as in FTIK. Based on the above problems, reserchers are interested to observe, analyze the access bandwidth at USM that occured during the period of active classes and the end of the course by means of internet access at USM monitoring using NDLC (Network Development Life Cycle) and will appear in the display MRTG. Objectives to be achieved by theresearcher is output obtained from a study that is able to provide inout to the wisdom of allocating bandwidth has been hired can be used optimally by the entire academic community USM.

Mini-Rank: A Power-EfficientDDRx DRAM Memory Architecture

Memory power consumption has become a severe concern in multi-core computer platforms. As memory data rate, capacity and bandwidth are being pushed higher and higher, the power consumption of memory systems becomes a significant part in the overall system power profile. Conventional memory systems do not provide an efficient mechanism for managing its power and performance tradeoff. We propose a novel mini-rank architecture for DDRx memories to reduce memory power consumption by breaking each DRAM rank into multiple narrow mini-ranks and activating fewer devices for each request. We also propose a heterogeneous mini-rank design to further improve the performance-power tradeoff for each workload based on its memory access behavior and bandwidth requirement. The evaluation results show that homogeneous mini-rank significantly reduces memory power with small performance loss. For instance, using four-core multiprogramming workloads, a x32 mini-rank configuration reduces memory power by 19.5 percent with 1.3 percent performance loss on average for memory-intensive workloads. Heterogeneous mini-rank further improves the balance between the performance and power saving. For instance, it reduces the memory power by up to 38.0 percent with an average performance loss of 2.4 percent, compared with a conventional memory system. In comparison, the x32 homogeneous mini-rank reduces memory power by up to 25.4 percent; while the x8 homogeneous mini-rank incurs performance loss by up to 19.3 percent. Furthermore, heterogeneous mini-rank achieves consistently good performance-power tradeoff for workloads made by programs of diverse memory access behavior and bandwidth requirement.

Adaptive joint bandwidth and power allocation in heterogeneous wireless access environment

Joint bandwidth and power allocation for a multi-radio access (MRA) system in a heterogeneous wireless access environment is studied. Since both the number of users being served by the system and the wireless channel state are time-varying, the optimal resource allocation is no longer a static optimum and will change with the varying network state. Moreover, distributed resource allocation algorithms that require iterative updating and signaling interactions cannot converge in negligible time. Thus, it is unrealistic to assume that the active user number and the wireless channel state remain unchanged during the iterations. In this paper, we propose an adaptive joint bandwidth and power allocation algorithm based on a novel iteration stepsize selection method, which can adapt to the varying network state and accelerate the convergence rate. A distributed solution is also designed for the adaptive joint resource allocation implementation. Numerical results show that the proposed algorithm can not only track the varying optimal resource allocation result much more quickly than a traditional algorithm with fixed iteration stepsize, but can also reduce the data transmission time for users and increase the system throughput.

A Survey for Replica Placement Techniques in Data Grid Environment

In data grids, data replication on variant nodes can change some problems such as response time and availability. Also, in data replication, there are some challenges to finding the best replica efficiently in relation to performance and location of physical storage systems. In this paper, various replica placement strategies are discussed. These replica placement strategies are available in the works. Replica placement contains recognizing the best possible node to duplicate data based on network latency and user request. These strategies measure and analyze different parameters such as access cost, bandwidth consumption, scalability, execution time and storage consumption. This paper also analyses the performance of various strategies with respect to the parameters mentioned above in data grid.

Analysis of PolSK based FSO system using wavelength and time diversity over strong atmospheric turbulence with pointing errors

Free space optics (FSO) or wireless optical communication systems is an evolving alternative to the current radio frequency (RF) links due to its high and secure datarates, large license free bandwidth access, ease of installation, and lower cost for shorter range distances. These systems are largely influenced by atmospheric conditions due to wireless transmission; requirement of line of sight (LOS) propagation may lead to alignment problems in turn pointing errors. In this paper, we consider atmospheric turbulence and pointing errors are the major limitations. We tried to address these difficulties by considering polarization shift keying (PolSK) modulated FSO communication system with wavelength and time diversity. We derived the closed form expressions for estimation of the average bit error rate (BER) and outage probability, which are vital system performance metrics. Analytical results are shown considering different practical cases.

SOS: A Distributed Mobile Q&A SystemBased on Social Networks

Recently, emerging research efforts have been focused on question and answer (Q&A) systems based on social networks. The social-based Q&A systems can answer non-factual questions, which cannot be easily resolved by web search engines. These systems either rely on a centralized server for identifying friends based on social information or broadcast a user's questions to all of its friends. Mobile Q&A systems, where mobile nodes access the Q&A systems through Internet, are very promising considering the rapid increase of mobile users and the convenience of practical use. However, such systems cannot directly use the previous centralized methods or broadcasting methods, which generate high cost of mobile Internet access, node overload, and high server bandwidth cost with the tremendous number of mobile users. We propose a distributed Social-based mObile Q&A System (SOS) with low overhead and system cost as well as quick response to question askers. SOS enables mobile users to forward questions to potential answerers in their friend lists in a decentralized manner for a number of hops before resorting to the server. It leverages lightweight knowledge engineering techniques to accurately identify friends who are able to and willing to answer questions, thus reducing the search and computation costs of mobile nodes. The trace-driven simulation results show that SOS can achieve a high query precision and recall rate, a short response latency and low overhead. We have also deployed a pilot version of SOS for use in a small group in Clemson University. The feedback from the users shows that SOS can provide high-quality answers.

Radio-frequency dispersive detection of donor atoms in a field-effect transistor

Radio-frequency dispersive read-out can provide a useful probe to nano-scale structures such as nano-wire devices, especially when the implementation of charge sensing is not straightforward. Here we demonstrate dispersive `gate-only' read-out of phosphor donors in a silicon nano-scale transistor. The technique enables access to states that are only tunnel-coupled to one contact, which is not easily achievable by other methods. This allows us to locate individual randomly placed donors in the device channel. Furthermore, the setup is naturally compatible with high bandwidth access to the probed donor states and may aid the implementation of a qubit based on coupled donors.