Wireless Communication

T. Chindrella Priyadharshini ¹, S. Neelakandan ¹

Affiliations
1 Anna University, Chennai, IN

Abstract

This paper proposes a cache consistency scheme based on a previously proposed architecture for caching database data in MANETs. The original scheme for data caching stores the queries that are submitted by requesting nodes in special nodes, called query directories (QDs), and uses these queries to locate the data (responses) that are stored in the nodes that requested them, called caching nodes (CNs). The consistency scheme is server-based in which control mechanisms are implemented to adapt the process of caching a data item and updating it by the server to its popularity and its data update rate at the server. The system implements methods to handle disconnections of QD and CN nodes from the network and to control how the cache of each node is updated or discarded when it returns to the network. Estimates for the average response time of node requests and the average node bandwidth utilization are derived in order to determine the gains (or costs) of employing our scheme in the MANET. Moreover, ns2 simulations were performed to measure several parameters, like the average data request response time, cache update delay, hit ratio, and bandwidth utilization. The results demonstrate the advantage of the proposed scheme over existing systems.

Keywords

Data Caching, Cache Consistency, Invalidation, Server-Based Approach, MANET.

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S. Neelakandan ¹, T. Chindrella Priyadharshini ²

Affiliations
1 Department of Information Technology, Vel Tech MultiTech Dr Rangarajan Dr sakunthala Engineering College, Chennai, TamilNadu, IN
2 Vel Tech MultiTech Dr Rangarajan Dr Sakunthala Engineering College, Chennai, TamilNadu, IN

Abstract

The irregularly connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. In this transmission, conventional routing schemes would fail, because they try to establish complete end to-end paths, before any data is sent. To deal with this intermittent networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention which can significantly degrade their performance. With this in mind, we look into a number of ―single-copy‖ routing schemes that use only one copy per message, and hence significantly reduce the resource requirements of flooding-based algorithms. We perform a detailed exploration of the single-copy routing space in order to identify efficient single-copy solutions that (i) can be employed when low resource usage is critical, and (ii) can help improve the design of general routing schemes that use multiple copies. We also propose a theoretical framework that we use to analyze the performance of all single-copy schemes presented, and to derive upper and lower bounds on the delay of any scheme.

Keywords

Delay Tolerant Networks, Intermittent Connectivity, Routing.

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S. Neelakandan ¹, T. Chindrella Priyadharshini ²

Affiliations
1 Department of Information Technology, Vel Tech Multi Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Chennai, IN
2 Department of Information Technology, Anna University, Chennai, IN

Abstract

In mobile ad hoc network (MANET) the designing of multicast transmission is a challenge due to the difficulty in group membership management, multicast packet forwarding, and the maintenance of multicast structure over the dynamic network topology for a large group size or network size. For this, we propose a novel Robust and Scalable Geographic Multicast Protocol (RSGM). Several virtual architectures are used in the protocol without need of maintaining state information for more robust and scalable membership management and packet forwarding in the presence of high network dynamics due to unstable wireless channels and node movements. Specifically, scalable and efficient group membership management is performed through a virtual-zone-based structure, and the location service for group members is integrated with the membership management. Both the control messages and data packets are forwarded along efficient tree-like paths, but there is no need to explicitly create and actively maintain a tree structure. The stateless virtual-tree-based structures significantly reduce the tree management overhead, support more efficient transmissions, and make the transmissions much more robust to dynamics. Geographic forwarding is used to achieve further scalability and robustness. To avoid periodic flooding of the source information throughout the network, an efficient source tracking mechanism is designed. The results demonstrate that RSGM can scale to a large group size and a large network size, and can more efficiently support multiple multicast groups in the network. Compared to existing protocols ODMRP and SPBM, RSGM achieves a significantly higher delivery ratio under all circumstances, with different moving speeds, node densities, group sizes, number of groups, and network sizes. RSGM also has the minimum control overhead and joining delay.

Keywords

Mobile Ad Hoc Networks, Multicast Routing, Robust, Scalable, Wireless Networks.

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