Ad hoc wireless distribution service

About: Ad hoc wireless distribution service is a research topic. Over the lifetime, 17734 publications have been published within this topic receiving 488205 citations.

Supporting cooperative caching in ad hoc networks

Abstract: Most researches in ad hoc networks focus on routing and not much work has been done on data access. A common technique used to improve the performance of data access is caching. Cooperative caching, which allows the sharing and coordination of cached data among multiple nodes, can further explore the potential of the caching techniques. Due to mobility and resource constraints of ad hoc networks, cooperative caching techniques designed for wired networks may not be applicable to ad hoc networks. In this paper, we design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: CacheData, which caches the data, and CachePath, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (HybridCache), which can further improve the performance by taking advantage of CacheData and CachePath while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes.

On the capacity of hybrid wireless networks

Abstract: This paper involves the study of the throughput capacity of hybrid wireless networks. A hybrid network is formed by placing a sparse network of base stations in an ad hoc network. These base stations are assumed to be connected by a high-bandwidth wired network and act as relays for wireless nodes. They are not data sources nor data receivers. Hybrid networks present a tradeoff between traditional cellular networks and pure ad hoc networks in that data may be forwarded in a multihop fashion or through the infrastructure. It has been shown that the capacity of a random ad hoc network does not scale well with the number of nodes in the system. In this work, we consider two different routing strategies and study the scaling behavior of the throughput capacity of a hybrid network. Analytical expressions of the throughput capacity are obtained. For a hybrid network of n nodes and m base stations, the results show that if m grows asymptotically slower than √n, the benefit of adding base stations on capacity is insignificant. However, if m grows faster than √n, the throughput capacity increases linearly with the number of base stations, providing an effective improvement over a pure ad hoc network. Therefore, in order to achieve nonnegligible capacity gain, the investment in the wired infrastructure should be high enough.

Ad hoc QoS on-demand routing (AQOR) in mobile ad hoc networks

Abstract: We introduce a resource reservation-based routing and signaling algorithm, Ad hoc Qos on-demand routing (AQOR), that provides end-to-end quality of service (QoS) support, in terms of bandwidth and end-to-end delay, in mobile ad hoc networks (MANETs). The increasing use of MANETs for transferring multimedia applications such as voice, video and data, leads to the need to provide QoS support. To perform accurate admission control and resource reservation in AQOR, we have developed detailed computations that allow us to estimate the available bandwidth and end-to-end delay in unsynchronized wireless environment. AQOR also includes efficient mechanisms for QoS maintenance, including temporary reservation and destination-initiated recovery processes. The performance of AQOR is studied in detail by simulation using OPNET Modeler. The results validate that AQOR provides QoS support in ad hoc wireless networks with high reliability and low overhead.

A framework for reliable routing in mobile ad hoc networks

Abstract: Mobile ad hoc networks consist of nodes that are often vulnerable to failure. As such, it is important to provide redundancy in terms of providing multiple node-disjoint paths from a source to a destination. We first propose a modified version of the popular AODV protocol that allows us to discover multiple node-disjoint paths from a source to a destination. We find that very few of such paths can be found. Furthermore, as distances between sources and destinations increase, bottlenecks inevitably occur and thus, the possibility of finding multiple paths is considerably reduced. We conclude that it is necessary to place what we call reliable nodes (in terms of both being robust to failure and being secure) in the network for efficient operations. We propose a deployment strategy that determines the positions and the trajectories of these reliable nodes such that we can achieve a framework for reliably routing information. We define a notion of a reliable path which is made up of multiple segments, each of which either entirely consists of reliable nodes, or contains a preset number of multiple paths between the end points of the segment. We show that the probability of establishing a reliable path between a random source and destination pair increases considerably even with a low percentage of reliable nodes when we control their positions and trajectories in accordance with our algorithm.

Vehicular Ad Hoc Networks (VANETs): Challenges and Perspectives

Abstract: Vehicular Ad hoc Network (VANET), a subclass of mobile Ad Hoc networks (MANETs), is a promising approach for future intelligent transportation system (ITS). These networks have no fixed infrastructure and instead rely on the vehicles themselves to provide network functionality. However, due to mobility constraints, driver behavior, and high mobility, VANETs exhibit characteristics that are dramatically different from many generic MANETs. This article provides a comprehensive study of challenges in these networks, which we concentrate on the problems and proposed solutions. Then we outline current state of the research and future perspectives. With this article, readers can have a more thorough understanding of vehicle ad hoc networking and the research trends in this area.