Research
Secured Localized Broadcasting in Wireless Ad-Hoc Networks
Broadcasting, one of the fundamental operations of the wireless ad-hoc networks, can be implemented using two approaches i.e static and dynamic. In broadcasting a node disseminates a message to all other nodes within the network. Usually in static approach the forwarding or non-forwarding status of the node is determined by a globally known priority function and local topology information. The static approach can achieve a constant approximation factor to optimal solution only if position information is available which is not possible in all cases. This paper shows that constant approximation to optimal solution can be obtained using connectivity information only. The status of each node is determined ‘on-the-fly’ i.e while the broadcasting process is being done. This local broadcast algorithm can achieve both full delivery and constant approximation to the optimal solution. The security issues can be solved by comparing the expected and perceived packet delivery ratios.
Performance Comparison of Terrestrial DVB Detection using LDPC and Turbo Codes
Last-generation and future wireless communication standards, such as DVB-T2 or DVB-NGH, are including multi-antenna transmission and reception in order to increase bandwidth efficiency and receiver robustness. The main goal is to combine diversity and spatial multiplexing in order to fully exploit the multiple-input multiple output (MIMO) channel capacity. Full-rate full-diversity (FRFD) space-time codes (STC) such as the Golden code are studied for that purpose. However, despite their larger achievable capacity, most of them present high complexity for soft detection, which hinders their combination with soft-input decoders in bit-interleaved coded modulation (BICM) schemes. This article presents a low complexity soft detection algorithm for the reception of FRFD space-frequency block codes in BICM orthogonal frequency division multiplexing (OFDM) systems and gives the performance comparision using Ldpc and Turbo codes. The proposed detector maintains a reduced and fixed complexity, avoiding the variable nature of the list sphere decoder (LSD) due to its dependence on the noise and channel conditions. Complexity and simulation based performance results are provided which show that the proposed detector performs close to the optimal log-maximum a posteriori (MAP) detection in a variety of DVB-T2 broadcasting scenarios.
A Novel Unified Power Quality Conditioning System for Power Quality Improvement and Bidirectional Power Flow Control for Windmill
This paper proposes a new approach of unified power quality conditioner which is made up of a matrix converter to mitigate the current harmonics, voltage sags and swells and control the power flow with Bi directional capability for windmill. Matrix converter injects the compensation voltage on the load-side, so it is possible to mitigate the voltage sag/swell problems, resulting in an efficient solution for mitigating voltage and current related power quality problems. Thus, the proposed topology can mitigate the voltage fluctuations and current harmonics without energy storage elements and the total harmonic distortion produced by the system also very low. Due to the bidirectional power flow capability of matrix converter the proposed unified power quality conditioner capable to control the power flow of the windmill more over it also transfer power bi -directional. The space-vector modulation (SVM) is used to control the matrix converter. Matlab/Simulink based simulation results are presented to validate the approachstorage elements and the total harmonic distortion produced by the system also very low.Due to the bidirectional power flow capability of matrix converter the proposed unified power quality conditioner capable to control the power flow of the windmill more over it also transfer power bi -directional. The space-vector modulation (SVM) is used to control the matrix converter. Matlab/Simulink based simulation results are presented to validate the approach.
