Advanced heterogeneous vehicular network (AHVN) is a promising architecture for providing vehicular services in the next generation of vehicular networks. AHVN is an integrated architecture between vehicular ad hoc networks and existing cellular wireless networks. In this work, we propose a Multihop vehicular connectivity model in V2V system, which depends on the physical characteristics of the roadways and false hop initiation connectivity. Then, we determine the failure probability of vehicular connectivity in V2V system. Based on interoperability utility, we employ the failure connectivity probability as a handover criterion to communicate with V2R networks. Subsequently, we propose an efficient medium access control (MAC) method based on collaborative codes for resource management in AHVN. As a result, we determine the failure access probability by employing a Markov chain model. The analysis of the proposed MAC in terms of transmission capacity, delay and access failure probability is driven. The numerical and simulation results demonstrate the effectiveness of the proposed framework.

In this paper, the cellular communications using high altitude platform (HAP) will be discussed including the coverage analysis and design. The cells are analyzed showing the main parameters affecting its shape, layout and area which are important in the cellular design stage. This HAP cellular system is very important to cross the gap of difficult extension of ground infrastructure especially for sparsely populated areas needing communications services. The system design is explained where the footprint of the HAP cell is demonstrated and the overall cellular layout is established. As a case study, the coverage of the HAP cellular system is proved to cover some areas in the Kingdom of Saudi Arabia (KSA) using several scenarios such as populated as well as long highways passing through desert areas. The HAP cells are generated using spot-beam antennas which are practically candidate. The simulation results show that a single HAP can provide hundreds of microcells for urban areas while covering very long highways that can extend to several hundreds of kilometers which is very useful in covering the long highways linking sparsely separated cities in KSA.

In this paper, we present a new Petri Net (PN) approach to model the IEEE 802.16 MAC Protocol called Higher-Order Stochastic Reward Net (HOSRN) and through the application of the proposed rule. HOSRN is used as a modeling formalism as it readily captures the quality of service requirements of the traffic classes. We apply HOSRN to verify the effectiveness of QoS of the protocol using Reachability graph.

Increased employment of WSN (Wireless Sensor Network) in real life applications and their hostile and remote locations accelerate demand of security in WSN. Publicly accessible wireless communication channel also makes WSN vulnerable to numerous security attacks. Scarcity of resources acquaints new sort of challenges and difficulties during implementation of effective security mechanisms. In this paper, we evaluate and compare performance of three different security mechanisms (ECRKS, CKP and AP scheme). ECRKS (Energy-efficient, Connected, Resilient Key pre-distribution Scheme) is based upon multi hop communication architecture specifically designed for homogeneous WSN. Clustering based protocols, AP (Asymmetric pre-distribution) scheme and CKP (Clustering based Key management Protocol) are proposed for heterogeneous WSN. All the above mentioned schemes are simulated in MATLAB to evaluate their effectiveness and suitability for WSN. Simulation result shows that CKP outperforms other two schemes in terms of transmission distance, memory burden, energy dissipation and resilience.

This paper proposes an image encryption scheme based on chaotic system with changeable parameters depending on plain-image. A generalized Arnold map, whose control parameters are changeable and image-dependent during the iteration procedure, is utilized to generate chaotic orbits applied to permute the pixel positions. A diffusion function is also designed to realize the diffusion effect by piece-wise linear chaotic map. In both the permutation process and the diffusion process, the keystreams generated by chaotic maps are all strongly dependent on plain-image, and thereby can improve the encryption security efficiently. The major merits of the proposed image encryption scheme include a huge key space, good statistical nature resisting statistical analysis attack, differential attack, and good resistance against known-plaintext attack and chosen-plaintext attack, etc. Experimental results have been carried out with detailed analysis to show that the proposed scheme can be a potential candidate for practical image encryption.

Many of the signature schemes are proposed in which the t out of n threshold schemes are deployed; but they still lack the property of security. In this paper, we have discussed implementation of improved CCH1 and improved CCH2 proxy multi-signature scheme based on elliptic curve cryptosystem. We have represented time complexity, space complexity and computational overhead of improved CCH1 and CCH2 proxy multi-signature schemes. We have presented cryptanalysis of improved CCH2 proxy multi-signature scheme and showed that improved CCH2 scheme is suffered from various attacks i.e. forgery attack and framing attack.

Medical Magnetic Resonance Images (MRI) is characterized by a composition of small differences in signal intensities between different tissues types. Thus ambiguities and uncertainties are introduced in image formation. In this paper, review of the current approaches in the tissue segmentation of MR Brain Images has been presented. The segmentation algorithms has been divided into four categories which is able to deal with different intensity non-uniformity as adaptive spatial Fuzzy C - means, Markov Random Field, Fuzzy connectedness method and atlas based re-fuzzy connectedness. The performance of these segmentation methods have been compared in terms of validation metric as dice similarity coefficient, overlap ratio and Jaccard coefficient. The comparison of all validation metric at different levels of intensity non-uniformity shows that adaptive Fuzzy C - means clustering segmentation method give better result in segmentation of brain tissue.

PACTS (Parallelized Adaptive Cipher with Transposition and Substitution) is a new class of Symmetric Cryptographic Algorithm designed using traditional techniques to efficiently utilize the parallel computing capabilities of the modern computing systems. It overcomes the performance inconsistencies prevalent in conventional cryptographic algorithms when they are implemented in different computing systems with different processing capabilities. The size of the key and the plain text blocks of PACTS are each 1024-bits. The adaptive nature of this algorithm is achieved by incorporating flexibility in the size of the key and plain text sub-blocks and the number of rounds. Level of Intra-packet parallelization, variety in grain size and the required security strength are achieved by suitably deciding the sub-block size. Flow of the algorithm is made dynamic by determining the execution steps at runtime using the value of the key. In spite of these advantages PACTS always produces the same cipher text block for a particular plain text block when the same key is used. CBC mode along with 2-way and 4 way Interleaved CBC modes are employed to overcome this problem. The performance of the PACTS in ECB, CBC and Interleaved CBC modes are analyzed with implementations in shared memory parallel computing environment using OpenMP, Java Threads and MPI.