Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
As an important field of emerging technology,\r\nwireless sensor networks (WSN) offer many new possibilities\r\nfor applications such as target tracking and environmental\r\nsurveillance by allowing the observer to move around\r\nfreely. However, disseminating sensing data to the mobile\r\nobserver raises significant design challenges for the routing\r\nscheme. In addition, WSN often operate under certain\r\nenergy constraints, and therefore reducing energy dissipation\r\nin order to prolong the lifetime of the WSN is another\r\nchallenge that must be faced. Most proposed routing protocols\r\nfocus on achieving effective data dissemination and\r\nenergy efficiency at the same time as working to satisfy the\r\nrequirements of the mobile observer. However, almost all of\r\nthese methods use frequent rerouting as a way of handling\r\nthe mobility issue. Such rerouting increases both overheads\r\nand energy consumption, resulting in a trade-off between\r\nthe need for rerouting to optimize network operations and\r\nthat of maximizing network lifetime. This paper presents\r\nthe Energy-aware Grid-based Routing Scheme (EAGER)\r\nfor WSN with mobile observers, which is an approach that\r\nseeks to save more energy in the context of dynamic topology.\r\nIn this paper, EAGER is compared to other proposed\r\ngrid-based schemes by using extensive simulations. These\r\nsimulations clearly show that EAGER outperforms other grid-based schemes in terms of both energy efficiency and\r\nrouting performance....
The evolution of CDMA offered great advantages over the existing TDMA and FDMA techniques. But considering CDMA to be fit for still further advancements in mobile communication technologies is not up to the mark. There has been a great debate on the air link technologies most suitable for 4G wireless. In this paper we summarize certain issues and state possible solutions to address some of the issues that could make CDMA a plausible option to certain extent....
The digital textbook is a suitable medium for the\r\nprovision of customized education that fits each individual�s\r\nneeds, and for the ongoing changes in educational needs\r\nsuch as a self-directed learning ability. This paper reviews\r\nselection criteria for the wireless network to be applied to\r\ndigital textbook. At present, it is believed that wireless LAN\r\nwas selected for the digital textbook in Korea because it provides\r\na better data rate and greater cost-effectiveness than\r\nthe other wireless network technologies. However, wireless\r\nLAN is inferior to the other technologies in terms of mobility\r\nand security. The future wireless network for digital textbook\r\nwill be guaranteed that it can meet the requirements\r\nof data rate and mobility. Therefore, for the digital textbook\r\nwith characteristics of public welfare, it would be worthwhile\r\nto consider allowing the installation and operation of\r\nthe internal mobile WiMAX network....
As the wireless Internet services become widely\r\navailable, users become able to use various Internet services\r\nwithout restriction in location. In particular, the demands on\r\nwireless Internet services are becoming greater, because mobile\r\ndevices that support high mobility are getting smarter.\r\nHowever, if a user uses various wireless networks, much\r\nlimitation occurs in network setting when they move a network\r\ndifferent each other. This is because there are few appropriate\r\nhandover mechanisms to support a heterogeneous\r\nnetwork.We propose a fast-handover for heterogeneous networks\r\nthat utilizes MIH in PMIPv6 to support heterogeneous\r\nnetworks and to reduce the handover latency time.\r\nAnd the performance evaluation for the proposed method\r\nwas done separately for low speed and high speed mobility.\r\nThe result presented shows that the suggested method has\r\nreduced latency time by 26 % and packet losses by 90 %\r\n(Avg.)....
The protection of copyrights of digital images authors\r\nis one of the most important tasks set before watermarking.\r\nWhat is especially important is to ensure the high\r\nrobustness of a watermarked images against attacks, preventing\r\nthe reading of additional information about the author.\r\nIn addition, the used processing of the original image\r\nmust be absolutely invisible. The presented algorithm embeds\r\ninformation in a parallel wayââ?¬â?independently of the\r\nluminance and chrominance matrices in the spatial and frequency\r\ndomains. The main factor motivating the use of a\r\nparallel watermark embedding via the proposed way was the\r\nmutual complementing of robustness, offered by processing\r\nin spatial and frequency domains. Additional information is\r\nrecovered in a 2D cepstrum domain and in coefficients of\r\nthe cosine transform. The article shows a description of a\r\nmathematical model, tests of invisibility, effectiveness and\r\nthe robustness of the method were carried out. The robustness\r\nof the algorithm was shown against the following attacks:\r\nJPEG and JPEG2000 lossy compression, noise, median\r\nfiltering, Low-Pass and High-Pass filtering, desynchronization,\r\nsimple and inverse D/A conversion, majority cropping,\r\nphotomontage and affine transformsââ?¬â?rotation, scaling,\r\nshearing, translation....
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