Volume 16, Issue 2, October 2012

Performance Enhancement of Wireless Ad Hoc Network Using Cross Layer and Diversity Scheme [Full Text]

A. M . E. ALSAYAH, S. J. Muhammad, U. C. Ahamefula and S. H. Hadya.

Abstract— Ad hoc network provides efficient and innovative telecommunication technology scenarios where infrastructures are not accessible. This unique form of wireless network facilitates the use of reliable and efficient information and communication system in areas that are constrained by fixed line networks. However, numerous challenges limits its mobility leading to interference with other unpredictable radio station channel that potentially disrupts its network links and proper transportation as significant fraction of packets are lost resulting and or are received as erroneous. To overcome these limitations, the present study exploites potential technique that detects and uses reliable route among which include cross layer and diversity technique. The use of cross-layer measurements could be to detect various reliable routes while multi-path diversity improves the reliability of packet and route operating robustness. Integration of these techniques could potentially improve the reliability and effectiveness of wireless ad hoc network by leveraging interactions between spectrums of network layers. The present study provides developmental phases for cross layer ad hoc network protocols which are reliably supportive to congestion control and tolerant to delayed network. The study further investigated diversity schemes with focus on network coding and coding erasure implementation

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Multi-Band Stacked Microstrip Patch Antenna for Wireless Applications [Full Text]

Ishan Budhiraja, Mohammad Aftab Alam Khan, Mehwash Farooqui and Manoj Kumar Pal

Abstract— A microstrip antenna is well suited for wireless application due to their low weight, low volume, and low sensitivity to manufacturing tolerances. In the recent years, communication system often requires multiband antennas to avoid the use of different antennas. In this paper, multiband characteristic of two layers stacked different shapes geometries (Circle, Pentagon, Hexagon, Octagon) microstrip patch antenna is experimentally studied. It is a probe feed antenna for impedance matching with 50Ω coaxial cable. This antenna works well in the frequency range from 0-10GHz.The variations in the shapes likes circle, pentagon, hexagon and octagon of the stacked microstrip patch antenna have been analyzed, and it is found multi resonance with decreasing lower resonance frequency with changes in its shape. The return loss, directivity and gain have been measured with the help of IE3D Zealand software. 

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SIP Authentication Scheme Improvement based on Elliptic Curve Cryptography [Full Text]

Samaneh Sadat Mousavi Nik, Mohammad Hossien Yaghmaee Moghaddam and Mohammad Bagher Ghaznavi Ghoushchi

Abstract—Session Initiation Protocol (SIP) is a powerful signaling protocol that increasingly used for administrating Voice over IP (VoIP) phone calls and in current Internet protocols such as Hyper Text Transport Protocol (HTTP) and Simple Mail Transport Protocol (SMTP). SIP controls communications on the Internet for establishing, maintaining and terminating sessions. But The authentication mechanism proposed in SIP specification is based on HTTP Digest authentication which this scheme has security problems, such as off-line password guessing attacks and impersonate other parties or charge calls to others and etc. So, many researches proposed different schemes to secure the SIP authentication. In the year 2012, Tang et al. proposed a SIP authentication protocol using elliptic curve cryptography (ECC), but their scheme is insecure against off-line password guessing, registration and modification attacks. In this paper we try to propose an ECC-based authentication scheme for SIP to overcome such security problems. At the end, analysis of security of the ECC-based protocol shows that our scheme is suitable for the applications with higher security requirement.