8,748 research outputs found
Speed-Aware Routing for UAV Ad-Hoc Networks
In this paper we examine mobile ad-hoc networks (MANET) composed by unmanned
aerial vehicles (UAVs). Due to the high-mobility of the nodes, these networks
are very dynamic and the existing routing protocols partly fail to provide a
reliable communication. We present Predictive-OLSR an extension to the
Optimized Link-State Routing (OLSR) protocol: it enables efficient routing in
very dynamic conditions. The key idea is to exploit GPS information to aid the
routing protocol. Predictive-OLSR weights the expected transmission count (ETX)
metric, taking into account the relative speed between the nodes. We provide
numerical results obtained by a MAC-layer emulator that integrates a flight
simulator to reproduce realistic flight conditions. These numerical results
show that Predictive-OLSR significantly outperforms OLSR and BABEL, providing a
reliable communication even in very dynamic conditions.Comment: submitted to GlobeCom'13 Workshop - Wi-UA
Distributed Rate Allocation Policies for Multi-Homed Video Streaming over Heterogeneous Access Networks
We consider the problem of rate allocation among multiple simultaneous video
streams sharing multiple heterogeneous access networks. We develop and evaluate
an analytical framework for optimal rate allocation based on observed available
bit rate (ABR) and round-trip time (RTT) over each access network and video
distortion-rate (DR) characteristics. The rate allocation is formulated as a
convex optimization problem that minimizes the total expected distortion of all
video streams. We present a distributed approximation of its solution and
compare its performance against H-infinity optimal control and two heuristic
schemes based on TCP-style additive-increase-multiplicative decrease (AIMD)
principles. The various rate allocation schemes are evaluated in simulations of
multiple high-definition (HD) video streams sharing multiple access networks.
Our results demonstrate that, in comparison with heuristic AIMD-based schemes,
both media-aware allocation and H-infinity optimal control benefit from
proactive congestion avoidance and reduce the average packet loss rate from 45%
to below 2%. Improvement in average received video quality ranges between 1.5
to 10.7 dB in PSNR for various background traffic loads and video playout
deadlines. Media-aware allocation further exploits its knowledge of the video
DR characteristics to achieve a more balanced video quality among all streams.Comment: 12 pages, 22 figure
Two-Hop Routing with Traffic-Differentiation for QoS Guarantee in Wireless Sensor Networks
This paper proposes a Traffic-Differentiated Two-Hop Routing protocol for
Quality of Service (QoS) in Wireless Sensor Networks (WSNs). It targets WSN
applications having different types of data traffic with several priorities.
The protocol achieves to increase Packet Reception Ratio (PRR) and reduce
end-to-end delay while considering multi-queue priority policy, two-hop
neighborhood information, link reliability and power efficiency. The protocol
is modular and utilizes effective methods for estimating the link metrics.
Numerical results show that the proposed protocol is a feasible solution to
addresses QoS service differenti- ation for traffic with different priorities.Comment: 13 page
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