A new security model to prevent denial‐of‐service attacks and violation of availability in wireless networks

Wireless networks are deployed in many critical areas, such as health care centers, hospitals, police departments, and airports. In these areas, communication through the networks plays a vital role, and real‐time connectivity along with constant availability of the networks is highly important. However, one of the most serious threats against the networks availability is the denial‐of‐service attacks. In wireless networks, clear text form of control frames is a security flaw that can be exploited by the attackers to bring the wireless networks to a complete halt. To prevent the denial‐of‐service attacks against the wireless networks, we propose two distinct security models. The models are capable of preventing the attacks by detecting and discarding the forgery control frames belonging to the attackers. The models are implemented and evaluated under various experiments and trials. The results have proved that the proposed models significantly improve the security performance of the wireless networks. This gives advantage of safe communication that can substantially enhance the network availability while maintaining the quality of the network performance. Copyright © 2011 John Wiley & Sons, Ltd.     

Availability analysis under multiple link failures in WDM networks with shared-link connections

In optical Wavelength Division Multiplexing (WDM) networks, different protection schemes have been proposed in the literature, namely, dedicated protection and shared protection. Shared protection techniques significantly reduce the required spare capacity by providing the same level of availability as dedicated protection. However, current mission critical applications (which heavily depend on the availability of communication resources) require connection availability in the order of 99.999% or higher, which corresponds to a downtime of almost 5 min a year on the average. Therefore, in order to satisfy a connection serviceavailability requirement defined by the users Service Level Agreement in a cost-effective and resource-efficient way, network operators need a systematic mechanism to evaluate the network availability under multiple failure scenario to ensure that current network configuration can meet the required availability degree; otherwise, a network upgrade is required. Unfortunately, under multiple failure scenario, traditional availability analysis techniques based on reliability block diagrams are not suitable for survivable networks with shared spare capacity. Therefore, a new concept is proposed to facilitate the calculations of network availability. In this paper, we propose an analytical model for evaluating the availability of a WDM network with shared-link connections under multiple link failures. The analytical model is also verified using Monte Carlo simulation. The proposed model significantly contributes to the related areas by providing network operators with a quantitative tool to evaluate the system availability and, thus, the expected survivability degree of WDM optical networks with shared connections under multiple link failures.     

Energy efficient virtual MIMO communication for wireless sensor networks

Virtual multiple input multiple output (MIMO) techniques are used for energy efficient communication in wireless sensor networks. In this paper, we propose energy efficient routing based on virtual MIMO. We investigate virtual MIMO for both fixed and variable rates. We use a cluster based virtual MIMO cognitive model with the aim of changing operational parameters (constellation size) to provide energy efficient communication. We determine the routing path based on the virtual MIMO communication cost to delay the first node death. For larger distances, the simulation results show that virtual MIMO (2×2) based routing is more energy efficient than SISO (single input single output) and other MIMO variations.