Biblio
Intentional interference presents a major threat to the operation of the Global Navigation Satellite Systems. Adaptive notch filtering provides an excellent countermeasure and deterrence against narrowband interference. This paper presents a comparative performance analysis of two adaptive notch filtering algorithms for GPS specific applications which are based on Direct form Second Order and Lattice-Based notch filter structures. Performance of each algorithm is evaluated considering the ratio of jamming to noise density against the effective signal to noise ratio at the output of the correlator. A fully adaptive lattice notch filter is proposed, which is able to simultaneously adapt its coefficients to alter the notch frequency along with the bandwidth of the notch filter. The filter demonstrated a superior tracking performance and convergence rate in comparison to an existing algorithm taken from the literature. Moreover, this paper describes the complete GPS modelling platform implemented in Simulink too.
Tactical MANETs are deployed in several challenging situations such as node mobility, presence of radio interference together with malicious jamming attacks, and execrable terrain features etc. Jamming attacks are especially harmful to the reliability of wireless communication, as they can effectively disrupt communication between any node pairs. The nature of Tactical MANETs hinders ineffective most of existing reliable routing schemes for ordinary wireless mobile networks. Routing Protocols in Tactical MANET s face serious security and reliability challenges. Selecting a long lasting and steady-going route is a critical task. Due to the lack of accurate acquisition and evaluation of the transmission characteristics, routing algorithms may result in continual reconstruction and high control overhead. This paper studies the impact of jamming and interference on the common protocols of tactical communications and presents a neighbor dependency-based reliable routing algorithm. According to the neighbor dependency based on channel state information evaluated by Exponential Smoothing Method, how to select a neighboring node as the next hop will greatly affect the transmission reliability. Finally, the performance of the reliable routing protocol based on neighbor dependency is tested in OPNET, and compared with the classical AODV algorithm and the improved AODV based on link Cost (CAODV) algorithm. The simulation results show that the protocol presented in this paper has better data transmission reliability.