Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 4 Articles
Recently, several studies about proxy signature schemes have been conducted. In 2009, Yu et al. proposed an anonymous proxy\r\nsignature scheme attempting to protect the proxy signer�s privacy from outsiders. They claimed that their scheme can make the\r\nproxy signer anonymous. However, based on our research, we determined that this was not the case and the proxy signer�s privacy\r\nwas not anonymous. Hence, in this paper, we propose a new anonymous proxy signature scheme that truly makes the proxy signer\r\nanonymous while making it more secure and efficient when compared with Yu et al.�s scheme. Our proxy signature scheme consists\r\nof two contributions. First, we mainly use random numbers and bilinear pairings to attain the anonymous property. Secondly, we\r\nincrease the security and efficiency of our proxy in the design....
The availability of heterogeneous devices has rapidly changed the way people access theWorldWideWeb that includes rich content\r\napplications such as video streaming, 3D games, video conferencing, and mobile TV. However, most of these devices� (i.e., mobile\r\nphone, PDA, smartphone, and tablet) capabilities differ in terms of built-in software and library (what they can display), display size\r\n(how the content appears), and battery supply (how long the content can be displayed). In order for the digital contents to fit the\r\ntarget device, content adaptation is required. There have been many projects focused on energy-aware-based content adaptation\r\nthat have been designed with different goals and approaches. This paper reviews some of the representative content adaptation\r\nsolutions that have been proposed during the last few years, in relation to energy consumption focusing on wireless multimedia\r\nstreaming in mobile devices. Also, this paper categorizes the research work according to different classifications of multimedia\r\ncontent adaptation requirements. In addition, we discuss some energy-related challenges content adaptation systems....
Telecommunications operators and research institutions pay close attention to the issue of quality of service.The paper deals with\r\nmethods of admission control in IP networks, which is only one of the subsets of quality of service.There are two large groups of\r\nAC methods: parameter-based admission control and measurement-based admission control.The core of the paper is simulation\r\nof AC methods and algorithms for topology model in MATLAB. Our simulations are mainly focused on required bandwidth and\r\nloss rates. At the end of the paper there are compared results of simulations....
A bandwidth extension (BWE) algorithm from wideband to superwideband (SWB) is proposed for a scalable speech/audio codec\r\nthat uses modified discrete cosine transform (MDCT) coefficients as spectral parameters. The superwideband is first split into\r\nseveral subbands that are represented as gain parameters and normalized MDCT coefficients in the proposed BWE algorithm.\r\nWe then estimate normalized MDCT coefficients of the wideband to be fetched for the superwideband and quantize the fetch\r\nindices. After that, we quantize gain parameters by using relative ratios between adjacent subbands. The proposed BWE algorithm\r\nis embedded into a standard superwideband codec, the SWB extension of G.729.1 Annex E, and its bitrate and quality are compared\r\nwith those of the BWE algorithm already employed in the standard superwideband codec. It is shown from the comparison that\r\nthe proposed BWE algorithm relatively reduces the bitrate by around 19% with better quality, compared to the BWE algorithm in\r\nthe SWB extension of G.729.1 Annex E....
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