[Show abstract][Hide abstract] ABSTRACT: Surveilling the water territory of a country by installing an Underwater Surveillance Network (USN) is one of the prominent applications developed for underwater communication. The primary responsibility of a USN is to detect trespassers within the premises and to notify the activities to the responsible authority for further actions. Alike any surveillance network, a USN also possesses several security threats and may undergo several passive and/or active attacks. In this paper, we propose a noble secure communication suite which is resistible against most kind of known attacks. Our propose protocol aimed at gaining confidentiality, integrity and authenticity of the messages being exchanged within the cluster while taking into the consideration of the peculiarities of the underwater communication. Moreover, since our proposed scheme is designed for a cluster-based USN where routing layer activities are not eminent, it is embedded within a media access control (MAC) protocol.
[Show abstract][Hide abstract] ABSTRACT: Customarily, the design of an efficient routing protocol for Wireless Mesh Networks (WMNs) demands sufficient consideration of the pertinent features. This is due to the fact that WMNs can be permanent or semi-permanent networks. Moreover, a reliable path from the source to the destination can be maintained using an improved and better performance metrics. Currently, the most widely used performance metric is the minimum hop-count which is based on the assumption that communication links are either working well or not working at all. This assumption is true for wired networks however this is impractical for wireless networks where numerous links suffer from intermediate loss ratios, low throughput, interference and other inherent limitations. Consequently, researchers have proposed a number of performance metrics for WMNs. It has also been shown that integrating multiple performance metrics into a routing protocol is effective for attaining optimal performance since it is highly probable that a single performance metric will not be able to satisfy the comprehensive requirements of WMNs. This paper presents a technique of integrating multiple routing metrics in order to optimize the performance of a routing protocol. The proposed technique is implemented on Multicast Ad-hoc On-Demand Distance Vector (MAODV) routing protocol. Simulation results show a statistically significant performance improvement over standard MAODV for WMNs.
[Show abstract][Hide abstract] ABSTRACT: Efficient multicasting over Wireless Mesh Network (WMN) is challenging due to dynamic and multi-hop wireless communication among multicast group members. Multicast Ad hoc On-Demand Distance Vector (MAODV) protocol is a tree based multicast routing protocol that enables dynamic, self-starting, multi-hop routing between participating mobile nodes wishing to join or participate in a multicast group in Wireless Mesh Network (WMN). The mobility of mobile nodes often causes link breakage in the tree-based protocols which sometime results in tree partitioning and poor performance. In MAODV, when a broken link is detected between two nodes on the multicast tree, the node downstream to the break is responsible for initiating the repair of the broken link. After link repair, it is likely that the previous distance between the nodes (nodes downstream to the link breakage) and the group leader will not remain same. The shortest path from the group leader to the nodes downstream to the node which initiates link breakage is not ensured. Moreover, if the node attempting to repair a tree link break does not receive a response after certain attempts, it assumes that the multicast tree is not repairable currently and this leads to tree partitioning. In this paper, an improved link repair technique is proposed which ensures shortest path from any node to the group leader. Simulation results demonstrate significant improvement in performance metrics compared to standard MAODV.
[Show abstract][Hide abstract] ABSTRACT: MySQL is the most successful database system being used all over the world especially when small and medium size industries are trying to cut costs. In this paper, some performance matrices are evaluated for MySQL server and benchmark tests done on two different types of Linux distributions, Fedora and Ubuntu. For performance comparison, a low specification server is used to find out whether it can handle moderately loaded (such as SMEs) MySQL transactions. The paper evaluates the performance differences by tweaking some parameters of SysBench and measure the network, CPU performance, memory and database query time. The paper also analyzes the results and attempt to find out the reasons of performance variations.
[Show abstract][Hide abstract] ABSTRACT: Problem statement: Wireless Mesh Networks (WMNs) is an emerging technology for wireless environment. Since WMNs are permanent or semi-permanent network, an efficient and reliable path establishment is the core concern for such type of networks. Several performance metrics has been designed for WMNs such as Expected Transmission Count (ETX), Expected Transmission Time (ETT), interference Aware Routing Metric (iAWARE), Link Type Aware (LTA) Metric, Success Probability Product (SPP) and so on. However, each of these individual routing metric considered some selected features thus a single metric is inadequate for selecting the most reliable path. Consequently, it is necessary to integrate multiple performance metrics into a routing protocol to attain optimal performance. Approach: In this study we proposed a technique of integrating multiple metrics to improve the performance of a WMN routing protocol. This technique was implemented in Ad hoc On-Demand Distance Vector (AODV) routing protocol thus leading to the development of Integrated Metrics AODV (IM-AODV) routing protocol. Results: The simulation results indicated that IM-AODV protocol significantly outperformed the traditional AODV in WMNs environment. In a lightly loaded network the performance of IM-AODV is almost similar to AODV, however, in moderate to highly loaded network the performance of IM-AODV was improved by 10% (on average) compared to AODV. Conclusion/Recommendations: Incorporating multiple metrics in a routing protocol proved an effective mechanism for selecting the best path in a multi-hop wireless network (e.g. WMN) with loop free routing and avoiding highly loaded and lossy links. The proposed integrated metric scheme can also be considered for other routing protocols with simple modifications.
[Show abstract][Hide abstract] ABSTRACT: Worldwide Interoperability for Microwave Access (WiMAX) is a technology that bridges the gap between fixed and mobile access
and offer the same subscriber experience for fixed and mobile user. Demand for such type of mobile broadband services and
applications are growing rapidly as it provides freedom to the subscribers to be online wherever they are at a competitive
price with other significant facilities such as increasing amounts of bandwidth, using a variety of mobile and nomadic devices
etc. The earliest version of WiMAX is based on IEEE 802.16 and is optimized for fixed and nomadic access, which is further
extended to support portability and mobility based on IEEE 802.16e, also known as Mobile WiMAX. However, frequent topology
changes caused by node mobility make routing in Mobile WiMAX networks a challenging problem. In this study, we focus upon
those routing protocols especially designed for wireless networks. Here, we compare the performance of four ad hoc routing
protocols (AODV, DSR, OLSR and ZRP) for Mobile WiMAX environment under the assumption that each of the subscriber station
has routing capabilities within its own network. From our simulation, we found that ZRP and AODV protocols outperform DSR
KeywordsAODV-DSR-Mobile WiMAX-OLSR and ZRP
[Show abstract][Hide abstract] ABSTRACT: The rapid development in communication systems has forced system designer to explore higher and higher frequencies. Rain is a dominant source of attenuation at higher frequencies in tropical and subtropical regions. The knowledge of rain fade is essential in order to optimize system capacity and meet quality and reliability. This paper has predicted rain fades in a subtropical country Bangladesh. The rain intensity data are derived from forty years measured annual rainfall data. The converted rain intensity data is used to estimate rain fade for earth-space link at C, Ku and Ka-bands. The rain fade is also estimated using ITU-R recommended rain intensity and compared with those predicted based on converted data.
[Show abstract][Hide abstract] ABSTRACT: Wireless Mesh Networks (WMNs) are dynamically self-organized and self-configured, with the nodes in the network automatically establishing an ad hoc network and preserving the mesh connectivity. There are several features which might help to design an efficient routing protocol suitable for wireless mesh networks such as improved performance metrics, link or path optimization, mobility management, scalability, cross-layer design etc. Since WMNs are permanent or semi-permanent network, an efficient and reliable path establishment is the core concern for such type of networks. By using the improved performance metrics, a reliable path can be established between source and destination. Minimum hop-count is the metric most commonly used by existing routing protocols. This approach implicitly assumes that links either work well or don’t work at all. While often true in wired networks, this is not a reasonable approximation in the wireless case; since many wireless links have intermediate loss ratios, interference problem, low throughput etc. For this reason, several performance metrics are already designed for WMNs such as Expected Transmission Count (ETX), Expected Transmission Time (ETT), Interference Aware Routing Metric (iAWARE), Link Type Aware (LTA) Metric, Success Probability Product (SPP) and so on. However, each individual routing metric consider some features and it is difficult to satisfy all the requirements of WMNs by using a single metric. Consequently, it is necessary to integrate multiple performance metrics into a routing protocol to attain optimal performance. This paper proposes a technique of integrating multiple routing metrics to improve the performance of a routing protocol. This technique is implemented in Ad hoc On-Demand Distance Vector (AODV) routing protocol and corresponding performance has been investigated in wireless mesh environment. Simulation results demonstrate significant performance improvement over standard AODV in WMNs.
[Show abstract][Hide abstract] ABSTRACT: Summary Multicast routing is a key technology for modern communication networks. It sends a single copy of a message from a source to multiple receivers over a communication link that is shared by the paths to the receivers. This is especially appropriate in wireless environments where bandwidth is scarce and many users are sharing the same wireless channels. In particular, for WMNs, multicast can represent a huge enhancement of the network capacity by taking advantage of links which can be shared by multiple users to receive the same data, which is transmitted only once. To support multicasting, several multicast routing protocols are designed for Internet and Ad hoc networks. However, no specific multicast routing protocol is designed for WMNs. Therefore, the performance comparison of existing multicast routing protocols over wireless mesh networks is essential in order to analyze their behavior and effectiveness. This paper presents the simulation and analysis of the performance of existing proactive and reactive multicast routing protocols over WMNs. Three prominent multicast routing protocols are selected for performance comparison; they are On Demand Multicast Routing Protocol (ODMRP), Multicast Ad hoc On Demand Distance Vector (MAODV) Protocol and Multicast Open Shortest Path First (MOSPF). Among them, MOSPF is a proactive routing protocol while MAODV and ODMRP are reactive multicast routing protocols. MAODV fabricates and maintains a shared multicast tree for each multicast group and ODMRP is a mesh-based approach and uses a forwarding group concept. Our aim is to investigate the relative strength and weaknesses of each protocol.