Search results for "Distributed computing"
showing 10 items of 622 documents
Cooperative layer-2 based routing approach for hybrid wireless mesh networks
2013
In a Wireless Mesh Network (WMN), the convenience of a routing strategy strongly depends on the mobility of the intermediate nodes that compose the paths. Taking this behaviour into account, this paper presents a routing scheme that works differently accordingly to the node mobility. In this sense, a proactive routing scheme is restricted to the backbone to promote the use of stable routes. Conversely, the reactive protocol is used for searching routes to or from a mobile destination. Both approaches are simultaneously implemented in the mesh nodes so that the routing protocols share routing information that optimises the network performance. Aimed at guaranteeing the IP compatibility, the …
A secure intersection-based routing protocol for data collection in urban vehicular networks
2014
Data routing has gained great intention since the appearance of Vehicular Networks (VANETs). However, in the presence of attackers, reliable and trustworthy operations in such networks become impossible without securing routing protocols. In this paper, we target to study and design a secure routing protocol S-GyTAR for vehicular environments. Several kinds of routing techniques are proposed in the literature and could be classified into topology-based or position-based strategies. Position-based is the most investigated strategy in vehicular networks due to the unique characteristics of such networks. For this reason, this work is based on the well-known intersection-based routing protocol…
On the Interaction Between IEEE 802.11e and Routing Protocols in Mobile Ad-Hoc Networks
2005
The upcoming IEEE 802.11e standard was developed to offer QoS capabilities to WLAN, offering significative improvements to multimedia traffic. MANETs also benefit from this new technology since the most widely deployed and used wireless interfaces are IEEE 802.11 based. In this paper we expose results relative to the interaction of reactive routing protocols for MANETs and the IEEE 802.11e technology. We find that very substantial improvements in terms of throughput and normalized routing overhead are achieved due to increased routing responsiveness. We also detail the relation between the behavior experienced in each case and the internal mechanisms of the routing protocol being used, offe…
A Group-Based Protocol for Large Wireless AD-HOC and Sensor Networks
2008
Many routing protocols for ad-hoc networks and sensor networks have been designed, but none of them is based on groups. It is known that grouping nodes gives better performance to the group and to the whole system, thereby avoiding unnecessary message forwarding and additional overheads. We propose an approach where the network is split into several groups of sensors where connections between groups are established as a function of the proximity and the neighbor's available capacity (based on the sensor's energy). In this paper the network architecture is described with its mathematical description and the messages that are needed to proper operation. It is also simulated how much time is n…
Reliable Data Gathering in Tree-Based IEEE 802.15.4 Wireless Sensor Networks
2007
This paper describes a routing protocol for enhanced robustness in IEEE 802.15.4-based sensor networks, which also addresses typical MAC layer issues, including power management, synchronization and link reliability. The algorithm uses a single-path strategy in error-free scenarios and resorts to using alternative paths when communication errors are detected. Our proposal exploits implicit acknowledgement of reception, a feature which may be provided by data aggregation when a broadcast medium such as the wireless channel is used. Therefore MAC layer acknowledgements are not used and errors recovery relies on a caching and retransmission strategy. The protocol requires synchronization among…
Notice of Violation of IEEE Publication Principles: Reinforcement learning for P2P searching
2005
For a peer-to-peer (P2P) system holding a massive amount of data, an efficient and scalable search for resource sharing is a key determinant to its practical usage. Unstructured P2P networks avoid the limitations of centralized systems and the drawbacks of a highly structured approach, because they impose few constraints on topology and data placement, and they support highly versatile search mechanisms. However their search algorithms are usually based on simple flooding schemes, showing severe inefficiencies. In this paper, to address this major limitation, we propose and evaluate the adoption of a local adaptive routing protocol. The routing algorithm adopts a simple reinforcement learni…
IMRR and IMPR Routing Protocols For Inter and Intra Wireless Mesh Communications
2015
Given the evolution of wireless technologies, Wireless Mesh Networks (WMN) have appeared as an emerging low-cost solution to ensure last-mile connectivity to the Internet network. However, providing real-time and streaming applications, such as VoIP (Voice over IP) and VoD (Video on Demand), with a satisfying QoS level is considered as an important challenge within these networks. In this paper, we propose a QoS based routing protocol, called Hybrid QoS Mesh Routing (HQMR), jointly with a clustering algorithm to improve the scalability of mesh networks. HQMR is composed of two routing sub- protocols: a reactive QoS based routing protocol for intra-mesh infrastructure communications and a pr…
Evaluating a bound for MANETs routing protocols performance using graphs with activation windows
2008
In this paper we present an algorithm called STPA (shortest time path algorithm) which aims at providing a comparison tool for the evaluation of a bound for mobile ad hoc networks (MANETs) routing protocols performance. STPA provides an exhaustive evaluation of an ideal routing protocol. Based on the current position and state of the nodes it can determine factors like: how many complete messages get to the destination, which is the smallest amount of time required by a packet to get to the destination, which path followed each packet, and so on. This values would allow a protocol designer to improve or fine tune his proposal. We demonstrate that the complexity of the algorithm is O(sigma2)…
An optimized path-selection using airtime metric in OLSR networks: Implementation and testing
2008
Wireless mesh networks used for broadband access may be equipped with multiple Internet gateways. Using airtime metric as the main criterion for path selection is an effective method for achieving load-balancing in such a multi-homed mesh network. In this paper, we describe how the radio-aware path selection using airtime as a metric can be implemented in order to achieve this functionality, based on a modified version of an open source OLSR implementation. The paper presents both the principle of this method, its implementation and the empirical results which focus on testing the airtime metric functionality based on a deployed small-scale test network.
Performance Analysis in Spatially Correlated IEEE 802.11 Networks
2012
Wireless mesh networks are difficult to be characterized, especially under multi-hop traffic streams. The problem is that the local view of the channel and the correlation between the buffers of consecutive nodes in a stream path make complicated the identification of the contention level perceived by each station along the time. Such a figure is used in the models based on the so called decoupling assumption for evaluating the final scheduling of simultaneous channel access grants. In this paper we propose a simplified mesh network model focused on capturing the correlation due to the network topology and traffic routes rather than the access protocol state at each node. To this purpose, w…