Open Topics

Vol. 69, n° 11-12, November-December 2014
Content available on Springerlink

Smart selective encryption of H.264/AVC videos using confidentiality metrics

L. Dubois1 , W. Puech and J. Blanc-Talon2
(1) University of Montpellier II, France
(2) DGA, Bagneux, France
Abstract In the field of video protection, selective encryption (SE) is a scheme which ensures the visual security of a video by encrypting only a small part of the data. This paper presents a new SE algorithm for H.264/AVC videos in context-adaptive variable-length coding mode. This algorithm controls the amount of encrypted alternative coefficients (ACs) of the integer transform in the entropic encoder. Two visual quality measures, the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM), are used to measure the visual confidentiality level of each video frame and to control the amount of encrypted ACs. Moreover, a new psychovisual metric to measure the flickering is introduced, the so-called temporal structural similarity (TSSIM). This method can be applied on intra and inter frame video sequences. Several experimental results show the efficiency of the proposed method.
Keywords Selective encryptionH.264/AVC – Psychovisual metricsFlickeringVisual confidentiality

On the security of verifiably encrypted signature schemes in a multi-user setting

Kyung-Ah Shim1
(1) National Institute for Mathematical Sciences, Yuseong-gu, Daejeon, Korea
Abstract A verifiably encrypted signature provides a way to encrypt a signature under a third party’s public key and proves that the resulting ciphertext contains such a signature. In this paper, we analyze the security of three verifiably encrypted signature schemes in a multi-user setting in which an adversary is allowed to access adjudication oracles for different users, but the same adjudicator.
Keywords Verifiably encrypted signatureMulti-user settingRogue-key attackBilinear pairing

A hybrid architecture of cognitive decision engine based on particle swarm optimization algorithms and case database

Xiaobo Tan1 , Hang Zhang1 and Jian Hu2
(1) PLA University of Science and Technology, Nanjing, China
(2) Durham University, Durham, UK
Abstract The architecture of cognitive decision engine should enable fast decision making, long-term knowledge accumulating based on past operating experience, and capabilities of knowledge updating to adapt to new situations. In this paper, a hybrid architecture of cognitive decision engine based on particle swarm optimization algorithms and case database is proposed. Considering the user’s quality of service preferences and the wireless situations, how to determine the radio’s link parameters such as modulation type, symbol rate, and transmit power can be formulated as a multi-objective optimization problem. In the architecture, this problem is solved by using particle swarm optimization algorithms, which make cognitive radio have the fast decision-making ability when facing unknown wireless situations. The case database, which stores the past running experiences of the cognitive radio is also integrated into the proposed architecture to improve the radio’s response speed and endows the radio with the ability of learning from its previous operating experiences. Simulation results show the effectiveness of the architecture, and the proposed cognitive decision engine can dynamically and properly reconfigure the radio according to the changes in wireless environment.
Keywords Cognitive radio – Cognitive decision engineParticle swarm optimizationCase database

Raindrop size distribution and rainfall attenuation modeling in equatorial and subtropical Africa: the critical diameters

O. Adetan and T. J. Afullo1
(1) University of KwaZulu-Natal, Durban, South Africa
Abstract Raindrop sizes were obtained from Butare, Rwanda (2.6°S, 29.74°E) and Durban, South Africa (29°52′S, 30°58′E) using the Joss–Waldvogel RD-80 disdrometer. The obtained data is used for the analysis of the drop size distribution (DSD) and specific rainfall attenuation modeling in these African countries identified as equatorial (Butare) and subtropical (Durban) regions. The influence of the raindrop diameters that are critical to the DSD and specific rain attenuation at operating frequencies of 10–150 GHz is investigated using the estimated R 0.01 values for Butare and Durban. Parameter fittings for the proposed DSD models at these locations for different rain rate values are investigated. The proposed drop size distribution models are also compared with those of other countries. At operating frequency range 10 ≤ f ≤ 40 GHz, the specific attenuation in Rwanda tends to be higher when compared to Durban. However, at frequency above 40 GHz, Durban shows a higher specific attenuation than Rwanda. The largest contributions to the overall specific rain attenuation are formed by drop diameters in the range 1.5 ≤ D ≤ 3.5 and 1.0 ≤ D ≤ 3.0 mm for Rwanda and South Africa, respectively, especially at higher frequencies. A minimal contribution is observed at the larger diameters. The influence of the disdrometer bins on the attenuation due to rain is also analyzed for these locations. The estimation will be useful to properly design adequate fade margin levels and for the purpose of link budget design by service providers and system engineers in the regions.
Keywords Rain rateDrop size distributionCritical diametersSpecific rainfall attenuation

Ergodic and outage capacity maximization of cognitive radio networks in cooperative relay environment using optimal power allocation

Vidhyacharan Bhaskarand Barnali Dutta1
(1) SRM University, Tamilnadu, India
Abstract Cognitive radio solves the problem of scarcity of radio spectrum to a great extent in that it allows unlicensed users to coexist with licensed users. It allows effective utilization of radio spectrum by offering radio cells the ability of radio sensing and dynamic spectrum sharing. The throughput of spectrum sharing cognitive radio can be maximized by performing data transmission and spectrum sensing at the same time. Cooperative communications and networking allow distributed terminals in a wireless network. The main problem with cognitive radio is to sense the presence of primary users over a wide range of spectrum. Cooperative spectrum sensing is used here to detect those users more reliably. It is investigated whether cooperative communication for spectrum in cognitive radio enhances the efficiency of spectrum sharing. The maximum power that can be adapted by the secondary user without causing significant interference to a primary user is investigated. An algorithm is proposed for the same. Closed-form expression for ergodic throughput is derived for the systems and is compared with the conventional cognitive radio system. An expression for the outage capacity of the system is also derived for average transmit and interference power constraints under truncated channel information with fixed rate technique.
Keywords Spectrum sensingSpectrum sharing (SS)Cognitive radioErgodic and outage capacity – Cooperative relaying

Design of a dual-band microstrip antenna using particle swarm optimization with curve fitting

Jun-Jiat Tiang1, 2 , Mohammad Tariqul Islam1, Norbahiah Misran1 and Mandeep Jit Singh1
(1) Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor, Malaysia
(2) Multimedia University, Persiaran Multimedia, Selangor, Malaysia

Without Abstract

Indoor positioning with GPS and GLONASS-like signals use of new codes and a repealite-based infrastructure in a typical museum building

Ikhlas Selmi and Nel Samama1
(1) Institut Mines-Télécom, Télécom SudParis, France
Abstract In order to propose a solution for the indoor positioning question, several tests with the repealite-based (similar to Pseudolites and repeaters) system have been carried out. This system uses a single Global Navigation Satellite System signal transmitted by all the indoor antennas. These signals may interfere with the satellite ones outdoors. Hence, the noise level at the outdoor receiver will be higher and the error range larger. To avoid these effects, new codes called Indoor-Modified Binary Offset Carrier codes that are capable of reducing interference with outdoor signals are generated. To analyse the performance of these codes, we carry out a theoretical expression of cross-correlation functions. Then the deployment of the repealite based system in a typical building is simulated. The goal of this step is to compare the interference performance of the new code with the one already used (Gold codes for GPS band and maximal sequence for Glonass one). A specific interest is given to the spectral interference when adding the new signal’s spectrum in the considered frequency band.
Keywords Indoor positioningPseudolitesRepeatersRepealitesCodesBinary Offset Carrier (BOC) modulationBinary Coded Symbol (BCS)