IJITCS Vol. 2, No. 2, Dec. 2010
Cover page and Table of Contents: PDF (size: 130KB)
Within the last decade, the continuous development of mobile technology has motivated an intense research in mobile data services. Among these services, location-based services and location-dependant queries have attracted a lot of attention from the software industry as well as from researchers. Although a number of locations based service methods have been proposed, the performance is not satisfactory in the case of dynamic data management problems that introduce high overhead in update and query operations. In this paper, we introduce a proxy based distributed dynamic data management architecture for location based services that reduces network cost with required quality of service (QoS). The system proposes a distributed hierarchical database structure with collocated proxy for efficient service delivery to location-dependant queries especially Range Queries (RQ). The system that we propose have the following advantages. i) It performs efficient processing of location dependant queries, especially Range Queries spanning over multiple network cells ii) It reduces wireless communication between mobile devices and servers. iii) The system is scalable where location data is distributed and arranged hierarchically. We use proxy objects to carry out processing task for each mobile user. Thus proxies play an important role and in charge of routing the queries to different (distributed) databases and present the results to queries efficiently. Simulation study shows the effectiveness of our proposed architecture.[...] Read more.
Trusted Network Connect (TNC) proposes a hierarchical and scalable architecture to securely and efficiently control endpoints` admission to the trusted computing platform to implement message passing and resource sharing. But, not all endpoints support or run a functional TNC client performing integrity checking, which represents a security risk in lots of environments. We have to consider the problem how to make these "clientless endpoints" access to trusted networks. It is of significance for improving the TNC mechanism. To solve the problem above, under the framework of TNC, this paper comes up with a clientless endpoint authentication scheme named CEAS. CEAS designs five enforcement mechanisms and the related message format to authenticate and authorize clientless endpoints. Furthermore, after the endpoints have connected to the networks, their initial determinations may be dynamically modified according to the updated circumstances. The experiment results prove that CEAS has the capability of effectively and flexibly making clientless endpoints access to trusted networks in a controlled and secure manner.[...] Read more.
The de-noising of sensor data has become an important to research. Since the traditional de-noising method can’t achieve successful de-noising effect and the software-only method never meets a high real time capability. In this paper, we illustrate a novel threshold function based on the wavelet hard and soft threshold function. It is unlike ordinary function, which has overcome the defect such as the discontinuity of hard threshold function and an invariable dispersion between the estimated wavelet coefficients and the decomposed coefficients of soft threshold function. Moreover, we consider the hardware implementation of wavelet threshold filter on FPGA which adopt the pleated sheet structure of multiplier and fit to frame data. A detailed description of the simulation and implementation is given. Finally, the experiment result on-board is shown that our hardware implementation can meet the requirement of real-time signal processing.[...] Read more.
Hybrid wavelet and directional filter banks (HWD) is an effective multi-scale geometrical analysis method. Compared to wavelet transform, it can better capture the directional information of images. But the ringing artifact, which is caused by the coefficient quantization in transform domain, is the biggest drawback of image compression algorithms in HWD domain. In this paper, by researching on the relationship between directional decomposition and ringing artifact, an improved decomposition approach of HWD(IHWD) is roposed to reduce the ringing artifact. In addition, the IHWD algorithm and directional weighting model is applied into the JPEG2000 coding framework, and a new still magecompression algorithm IJPEG2000 is proposed. The experimental results show that IJPEG2000 has better performance than JPEG2000 whether on objective evaluation method or on subjective visual feeling.[...] Read more.
By studying the Kerberos authentication scheme, an improved authentication scheme is raised, which is based on Dynamic Password Method. In the improved scheme, user’s password can be effectively protected, and the authentication is double between users and severs. Also, the scheme can resist jacking connection attack. The improved scheme is more secure and more practical than the original one.[...] Read more.
In this paper, we present a string kernel based method for documents clustering. Documents are viewed as sequences of strings, and documents similarity is calculated by the kernel function. According to the documents similarity, spectral clustering algorithm is used to group documents. Experimental results shows that string kernel method outperform the standard k-means algorithm on the Reuters-21578 dataset.[...] Read more.
The quality assessment of the watermarked color image is one of the most important aspects that evaluate the performance of watermarking system. PSNR is the common quality assessment of the watermarked image. But the results measured by PSNR usually do not match to human vision well and result in misleading. The discrete cosine transform was used as the image analysis tools. The psychophysical research -- the luminance, texture, frequency and color masking on human vision were analyzed and used in masking strength calculation. Then a vision masking calculation method of image DCT coefficients was given in this paper. Based on the masking strength calculation, a new quality assessment of watermarked color image was proposed. Experimental results showed that the new quality assessment outperforms PSNR. The distorted image quality values calculated using the new quality assessment are consistent with the perception of human vision and have high correlation and consistency with subjective values.[...] Read more.
It has been commonly recognized that the current Internet faces serious security and scaling problems. To address these problems, the architecture of ID/locator separation is the focus of future Internet development.
However, the relevant authentication mechanism has not been proposed under this architecture. In this paper, we advance a new authentication mechanism called AuMID under ID/locator separation architecture, and describe the detailed procedures of access authentication and handoff authentication, and simultaneously give the deployment of authentication centers. Besides, AuMID uniquely introduces the Identity Tag which represents the terminal’s identity information to implement the sustainable authentication for the terminal. This mechanism adopts the challenge-response approach and achieves the double-way authentication between the terminal and access network. At the same time, by the use of Identify Tag AuMID successfully guarantees the authenticity of the source under ID/locator separation architecture. In conclusion, this paper gives a qualitative analysis for the scalability and security of this AuMID and an evaluation of handoff authentication delay.