Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
The virtualization of the network access layer has opened new doors in how we perceive networks. With this virtualization of the\r\nnetwork, it is possible to transform a regular PC with several network interface cards into a switch. PC-based switches are becoming\r\nan alternative to off-the-shelf switches, since they are cheaper. For this reason, it is important to evaluate the performance of PCbased\r\nswitches. In this paper, we present a performance evaluation of two PC-based switches, using Open vSwitch and LiSA, and\r\ncompare their performance with an off-the-shelf Cisco switch. The RTT, throughput, and fairness for UDP are measured for both\r\nEthernet and Fast Ethernet technologies. From this research, we can conclude that the Cisco switch presents the best performance,\r\nand both PC-based switches have similar performance. Between Open vSwitch and LiSA, Open vSwitch represents a better choice\r\nsince it has more features and is currently actively developed....
Thepaper presents a dynamic subchannel assignment algorithmbased on orthogonal frequency divisionmultiple access technology\r\noperating in the time division duplexing and a new cross-layer design based on a proposed routing protocol jointed with theMAC\r\nprotocol.The proposed dynamic sub-channel assignment algorithmprovides a newinterference avoidance mechanismwhich solves\r\nseveral drawbacks of existing radio resource allocation techniques in wireless networks using OFDMA/TDD, such as the hidden\r\nnode and exposed node problems, mobility, and cochannels interference in frequency (CCI). Besides, in wireless networks, when\r\na route is established, the radio resource allocation problems may decrease the end to end performance proportionally with the\r\nlength of each route. The contention at MAC layer may cause the routing protocol at network layer to respond by finding new\r\nroutes and routing table updates. The proposed routing protocol is jointed with theMAC protocol based on dynamic sub-channel\r\nassignment to ensure that the quality of service in multihop ad hoc networks is significantly improved....
The paper deeply analyzes a novel network-wide power management problem, called Power-Aware Routing and Network Design\r\nwith Bundled Links (PARND-BL), which is able to take into account both the relationship between the power consumption and the\r\ntraffic throughput of the nodes and to power off both the chassis and even the single Physical Interface Card (PIC) composing each\r\nlink. The solutions of the PARND-BL model have been analyzed by taking into account different aspects associated with the actual\r\napplicability in real network scenarios: (i) the time for obtaining the solution, (ii) the deployed network topology and the resulting\r\ntopology provided by the solution, (iii) the power behavior of the network elements, (iv) the traffic load, (v) the QoS requirement,\r\nand (vi) the number of paths to route each traffic demand. Among the most interesting and novel results, our analysis shows that\r\nthe strategy of minimizing the number of powered-on network elements through the traffic consolidation does not always produce\r\npower savings, and the solution of this kind of problems, in some cases, can lead to spliting a single traffic demand into a high\r\nnumber of paths....
The advances in localization based technologies and the increasing importance of ubiquitous computing and context-dependent\r\ninformation have led to a growing business interest in location-based applications and services. Today, most application\r\nrequirements are locating or real-time tracking of physical belongings inside buildings accurately; thus, the demand for indoor\r\nlocalization services has become a key prerequisite in some markets. Moreover, indoor localization technologies address the\r\ninadequacy of global positioning system inside a closed environment, like buildings. Based on this, though, this paper aims to\r\nprovide the reader with a review of the recent advances in wireless indoor localization techniques and system to deliver a better\r\nunderstanding of state-of-the-art technologies and motivate new research efforts in this promising field. For this purpose, existing\r\nwireless localization position system and location estimation schemes are reviewed, as we also compare the related techniques and\r\nsystems along with a conclusion and future trends....
Energy efficiency in cellular networks has received significant attention fromboth academia and industry because of the importance\r\nof reducing the operational expenditures and maintaining the profitability of cellular networks, in addition to making these\r\nnetworks ââ?¬Å?greener.ââ?¬Â Because the base station is the primary energy consumer in the network, efforts have been made to study base\r\nstation energy consumption and to find ways to improve energy efficiency. In this paper, we present a brief review of the techniques\r\nthat have been used recently to improve energy efficiency, such as energy-efficient power amplifier techniques, time-domain\r\ntechniques, cell switching, management of the physical layer through multiple-input multiple-output (MIMO) management,\r\nheterogeneous network architectures based on Micro-Pico-Femtocells, cell zooming, and relay techniques. In addition, this paper\r\ndiscusses the advantages and disadvantages of each technique to contribute to a better understanding of each of the techniques and\r\nthereby offer clear insights to researchers about how to choose the best ways to reduce energy consumption in future green radio\r\nnetworks....
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