Sensor network security solutions that have been proposed so far are mostly built on the assumption of a trusted environment, which is not very realistic so we need trust management before deploying any other security solution. Traditional trust management schemes that have been developed for wired and wireless ad-hoc networks are not suitable for wireless sensor networks because of higher consumption of resources such as memory and power. In this paper, we propose a novel lightweight group based trust management scheme (GTMS) for distributed wireless sensor networks in which the whole group will get a single trust value. Instead of using completely centralized or distributed trust management schemes, GTMS uses hybrid trust management approach that helps in keeping minimum resource utilization at the sensor nodes. 1
Mobile networks reuse frequency bands based on a color map to increase the capacity of the network. A handoff should occur when a mobile unit moves from the influence of one base station with weaker signal into another's that has stronger signal. Handoff behavior of all units is an important factor in quality of service of a mobile phone service. Handoff decisions, also called mobility decisions, are made by mobile phone based on the observed power from base stations. Premature, delayed or exceedingly sensitive decisions are considered poor decisions. Excessive poor decisions result in degradation of service quality in otherwise a healthy mobile system. Conventional research focuses on improving hand-off algorithms. Most of the published work on verification of effectiveness of handoff algorithms is analytical or focuses on data collected under pristine laboratory conditions. A unit that makes good mobility decisions, theoretically or in the laboratory, may not behave as expected in the real world however. We propose a process of evaluating hand off behavior using large amount of diagnostic phone data collected in the real world that is used for identification of adverse trends or aberrant behavior of various models. In this paper, we discuss a chi-square statistical test to evaluate the performance of specific mobile unit model by comparing the behavior of a test mobile unit against a wellestablished behavior profile. If the behavior of the test model deviates significantly from the well-established profile, it is considered deficient in its handoff behavior that deserves further analysis. The test was developed in such a way that a large amount of units can quickly be tested. The same test can be used to compare performance of all mobile phones in one region to performance of same mobile phones in other regions. Furthermore, our test is useful in determining difference of handoff behavior when the mobile units are moving in opposite directions.
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