Search results for "Relay"
showing 10 items of 86 documents
A TDMA-Based MAC Protocol Supporting Cooperative Communications in Wireless Mesh Networks
2011
This paper proposes a TDMA-based medium access control protocol which enables cooperative communications in multi-hop wireless mesh networks. According to the proposed scheme, each router at the two-hop neighbourhood of each other is allocated to a specific time slot for accommodating either direct or cooperative transmissions in a coordinated manner, controlled by mini-slots which are part of the time slot. 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 each packet transmission. By providing access priority to cooperative transmission through an optimal relay which is determined b…
ECAR: an Energy/Channel Aware Routing Protocol For Cooperative Wireless Sensor Networks
2011
International audience; The proliferation of low power networks like Wireless Sensor Networks (WSN) rose up new challenges. Power conservation and channel quality become the most important parameters. Obviously, hop count based routing protocols are no more adapted to such networks having power limitations and channel problems. Several alternatives were suggested to cope with these constraints. In MAC layer for example, cooperative protocols were designed to enhance the channel use: the neighbor nodes help the source to retransmit its packets. However, if the path proposed by the routing protocol contains poor channels, the cooperative communications will not save all the packets. Therefore…
RBCR: a Relay-Based Cooperative Routing Protocol for Cooperative Wireless Sensor Network
2011
International audience; In wireless sensor networks several constraints decrease communications performances. The main objective of this paper is to present a multi-objective routing algorithm RBCR that computes routing path based on the energy consumption and channel qualities. Additionally, the channel qualities are evaluated based on the presence of relay nodes. Compared to AODV and AODV associated to a cooperative MAC protocol, RBCR provides better performances.
A combined relay-selection and routing protocol for cooperative wireless sensor networks
2012
International audience; In wireless sensor networks several constraints decrease communications performances. In fact, channel randomness and energy restrictions make classical routing protocols inefficient. Therefore, the design of new routing protocols that cope with these constraints become mandatory. The main objective of this paper is to present a multi-objective routing algorithm RBCR that computes routing path based on the energy consumption and channel qualities. Additionally, the channel qualities are evaluated based on the presence of relay nodes. Compared to AODV and AODV associated to a cooperative MAC protocol, RBCR provides better performances in term of delivery ratio, power …
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…
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…
UAV Communication Strategies in the Next Generation of Mobile Networks
2020
| openaire: EC/H2020/857031/EU//5G!Drones The Next Generation of Mobile Networks (NGMN) alliance advocates the use of different means to support vehicular communications. This aims to cope with the massive data generated by these devices which could affect the Quality of Service (QoS) of the associated applications, but also the overall operation carried out by the vehicles. However, efficient communication strategies must be considered in order to select, for each vehicle, the communication mean ensuring the best QoS. In this paper, we tackle this issue and we propose efficient communication strategies for Unmanned Aerial Vehicles (UAVs). In addition to direct UAV-to-Infrastructure communi…
Secrecy analysis and learning-based optimization of cooperative NOMA SWIPT systems
2019
Non-orthogonal multiple access (NOMA) is considered to be one of the best candidates for future networks due to its ability to serve multiple users using the same resource block. Although early studies have focused on transmission reliability and energy efficiency, recent works are considering cooperation among the nodes. The cooperative NOMA techniques allow the user with a better channel (near user) to act as a relay between the source and the user experiencing poor channel (far user). This paper considers the link security aspect of energy harvesting cooperative NOMA users. In particular, the near user applies the decode-and-forward (DF) protocol for relaying the message of the source no…
Aircraft type-specific errors in AMDAR weather reports from commercial aircraft
2008
AMDAR (Aircraft Meteorological DAta Relay) automated weather reports from commercial aircraft provide an increasing amount of input data for numerical weather prediction models. Previous studies have investigated the quality of AMDAR data. Few of these studies, however, have revealed indications of systematic errors dependent upon the aircraft type. Since different airlines use different algorithms to generate AMDAR reports, it has remained unclear whether a dependency on the aircraft type is caused by physical properties of the aircraft or by different data processing algorithms. In the present study, a special AMDAR dataset was used to investigate the physical type-dependent errors of AMD…
On the Statistical Properties of Equal Gain Combining over Mobile-to-Mobile Fading Channels in Cooperative Networks
2010
Paper presented at the 2010 IEEE International Conference on Communications (ICC), Cape Town. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. Paper also available from the publisher: http://dx.doi.org/10.1109/ICC.2010.5501898 This article deals with the statistical analysis of equal gain combining (EGC) over mobile-to-mobile (M2M) fading channels in a dual-hop amplify-and-forward relay network. Here, we…