In this paper, we present an approximate aggregation principle to reduce the state space of an homogeneous Markov process. This method is then used to compute a bound of the asymptotic unavailability of a Markovian system. Finally, we show that calculating this dependability measure is of much interest even in different contexts, since the unavailability at time t of several ageing systems can ...

The paper proposes a framework that provides security in networks deployed in disaster areas. Traditional networks are not well suitable to use in such setting due to many unusual constraints such as long delays, high packet drop rates, unavailability of central trusted entity etc. Under such constraints existing security protocols do not work. Proposed here approach provides solutions for some...

Firewalls form the first line of defense in securing internal networks from the Internet. A Firewall only provides security if all traffic into and out of an internal network passes through the firewall. However, a single firewall through which all network traffic must flow represents a single point of failure. If the firewall is down, all access is lost. A common solution to this problem is to...

Identifying risks in military logistics planning is essential. Particularly, identifying risks that emanate due to unforeseen unavailability of key transport assets during a defence mission is vital to evaluate the robustness of contingencies built in to support the mission's logistics plan. An unforeseen unavailability of a transport may be caused by unscheduled maintenance or its assignment t...

In this paper, an energy conservation mechanism to maximize the unavailability interval and to improve the energy efficiency for the Power Saving Class in WiMAX are proposed. The proposed method can be implemented in commercial fields and is fully compatible with the 802.16 standard. It provides a systematic way to adjust the start frame number of the first sleep window, one of the relevant par...