2,270 research outputs found
An Efficient Network Coding based Retransmission Algorithm for Wireless Multicasts
Retransmission based on packet acknowledgement (ACK/NAK) is a fundamental
error control technique employed in IEEE 802.11-2007 unicast network. However
the 802.11-2007 standard falls short of proposing a reliable MAC-level recovery
protocol for multicast frames. In this paper we propose a latency and bandwidth
efficient coding algorithm based on the principles of network coding for
retransmitting lost packets in a singlehop wireless multicast network and
demonstrate its effectiveness over previously proposed network coding based
retransmission algorithms.Comment: 5 pages, 5 figure
Resource Allocation Frameworks for Network-coded Layered Multimedia Multicast Services
The explosive growth of content-on-the-move, such as video streaming to
mobile devices, has propelled research on multimedia broadcast and multicast
schemes. Multi-rate transmission strategies have been proposed as a means of
delivering layered services to users experiencing different downlink channel
conditions. In this paper, we consider Point-to-Multipoint layered service
delivery across a generic cellular system and improve it by applying different
random linear network coding approaches. We derive packet error probability
expressions and use them as performance metrics in the formulation of resource
allocation frameworks. The aim of these frameworks is both the optimization of
the transmission scheme and the minimization of the number of broadcast packets
on each downlink channel, while offering service guarantees to a predetermined
fraction of users. As a case of study, our proposed frameworks are then adapted
to the LTE-A standard and the eMBMS technology. We focus on the delivery of a
video service based on the H.264/SVC standard and demonstrate the advantages of
layered network coding over multi-rate transmission. Furthermore, we establish
that the choice of both the network coding technique and resource allocation
method play a critical role on the network footprint, and the quality of each
received video layer.Comment: IEEE Journal on Selected Areas in Communications - Special Issue on
Fundamental Approaches to Network Coding in Wireless Communication Systems.
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Evaluation of network coding techniques for a sniper detection application
This paper experimentally studies the reliability and delay of flooding based multicast protocols for a sniper detection application. In particular using an emulator it studies under which conditions protocols based on network coding deliver performance improvements compared to classic flooding. It then presents an implementation of such protocols on mobile phones
Speeding Multicast by Acknowledgment Reduction Technique (SMART)
We present a novel feedback protocol for wireless broadcast networks that
utilize linear network coding. We consider transmission of packets from one
source to many receivers over a single-hop broadcast erasure channel. Our
method utilizes a predictive model to request feedback only when the
probability that all receivers have completed decoding is significant. In
addition, our proposed NACK-based feedback mechanism enables all receivers to
request, within a single time slot, the number of retransmissions needed for
successful decoding. We present simulation results as well as analytical
results that show the favorable scalability of our technique as the number of
receivers, file size, and packet erasure probability increase. We also show the
robustness of this scheme to uncertainty in the predictive model, including
uncertainty in the number of receiving nodes and the packet erasure
probability, as well as to losses of the feedback itself. Our scheme, SMART, is
shown to perform nearly as well as an omniscient transmitter that requires no
feedback. Furthermore, SMART, is shown to outperform current state of the art
methods at any given erasure probability, file size, and numbers of receivers
Network Coding Channel Virtualization Schemes for Satellite Multicast Communications
In this paper, we propose two novel schemes to solve the problem of finding a
quasi-optimal number of coded packets to multicast to a set of independent
wireless receivers suffering different channel conditions. In particular, we
propose two network channel virtualization schemes that allow for representing
the set of intended receivers in a multicast group to be virtualized as one
receiver. Such approach allows for a transmission scheme not only adapted to
per-receiver channel variation over time, but to the network-virtualized
channel representing all receivers in the multicast group. The first scheme
capitalizes on a maximum erasure criterion introduced via the creation of a
virtual worst per receiver per slot reference channel of the network. The
second scheme capitalizes on a maximum completion time criterion by the use of
the worst performing receiver channel as a virtual reference to the network. We
apply such schemes to a GEO satellite scenario. We demonstrate the benefits of
the proposed schemes comparing them to a per-receiver point-to-point adaptive
strategy
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