Search results for "working"
showing 10 items of 2747 documents
A mini-slot-based cooperative MAC protocol for wireless mesh networks
2010
This paper proposes a TDMA-based medium access control protocol with cooperative communications enabled in wireless mesh networks. The proposed scheme is based on a multi-hop scenario which is extended from the conventional one-hop triangle cooperative transmission scenario. Benefiting from the elaborate mini-slot design, channel resources are fairly and efficiently allocated to each router so that no handshake is needed prior to every packet transmission. By giving priority for channel access to cooperative transmission performed by an optimal helper which is determined based on the received SNR, higher successful transmission rate can be achieved. Numerical results demonstrate that the pr…
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…
SUBOPTIMAL-OPTIMAL ROUTING FOR LAN INTERNETWORKING USING TRANSPARENT BRIDGES
1998
The current standard transparent bridge protocol IEEE-802.1D is based on the Spanning Tree (ST) algorithm. It has a very important restriction: it cannot work when the topology has active loops. Therefore, a tree is the only possible interconnection topology that can be used. The ST algorithm guarantees that the active topology is a tree discarding lines that form loops. However, because of this, network bandwidth cannot be fully utilized. Moreover, trees have a very serious bottleneck near the root. This paper proposes a new transparent bridge protocol for LAN interconnection that allows active loops. Therefore, strongly connected regular topologies like tori, hypercubes, meshes, etc., as…
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…
An adaptive timer for RPL to handle mobility in wireless sensor networks
2016
This paper focuses on the performance of wireless sensor networks characterized by a hybrid topology composed of mobile and static sensor nodes. The Routing Protocol for Low power and lossy networks (RPL), which is standardized as an IPv6 routing protocol for low power and lossy networks, uses the trickle timer algorithm to handle changes in the network topology. However, this algorithm is not well adapted to dynamic environments. This paper enhances the trickle timer in order to fit with mobility requirements. Most of previous works have improved this algorithm without considering the random movement of nodes. In this work, the proposed timer algorithm takes into consideration the random t…
Throughput and energy efficiency comparison of one-hop, two-hop, virtual relay and cooperative retransmission schemes
2010
Two main types of approaches exist for implementing cooperative communications at the MAC layer: virtual-hop relay and cooperative retransmission. While the virtual-hop relay schemes employ relay nodes to forward packets when higher end-to-end throughput can be achieved compared with the direct transmission, the cooperative retransmission schemes use relays to retransmit data only after the direct transmission fails. However, the performance of the these different approaches has not been compared in the literature, especially when energy efficiency is considered. In order to find out the best transmission scheme, this paper evaluates and compares the performance of the one-hop direct transm…