66,756 research outputs found
When To Pay Attention?: Asynchrony Requires A Trigger
LIDA is an integrated, comprehensive control architecture for autonomous agents capable of making complex decisions in dynamic environments. LIDA’s computational architecture consists of various modules that each operate asynchronously. However, the Global Workspace (GW) module, responsible for conscious attention, transfers information serially. There can be several computational techniques used to initiate the broadcast of content from the GW. The present study evaluated four techniques called “triggers” to start the GW broadcast under four different conditions. A parameter search was performed to find the optimum trigger parameters, followed by an investigation to identify the trigger(s) which were most useful for an efficient autonomous agent operating in an ALife domain. The Individual Activation Above Threshold (IAAT) trigger performed the best among all four triggers when used individually, whereas, the IAAT and No Broadcast Occurring (NBO) trigger combination outperformed all the other triggers individually, or in combination
Context-based Broadcast Acknowledgement for Enhanced Reliability of Cooperative V2X Messages
Most V2X applications/services are supported by
the continuous exchange of broadcast messages. One of the main
challenges is to increase the reliability of broadcast transmissions
that lack of mechanisms to assure the correct delivery of the
messages. To address this issue, one option is the use of
acknowledgments. However, this option has scalability issues
when applied to broadcast transmissions because multiple
vehicles can transmit acknowledgments simultaneously. To
control scalability while addressing reliability of broadcast
messages, this paper proposes and evaluates a context-based
broadcast acknowledgement mechanism where the transmitting
vehicles selectively request the acknowledgment of
specific/critical broadcast messages, and performs
retransmissions if they are not correctly received. In addition, the
V2X applications/services identify the situations/conditions that
trigger the execution of the broadcast acknowledgment
mechanism, and the receiver(s) that should acknowledge the
broadcast messages. The paper evaluates the performance of the
context-based broadcast acknowledgment mechanism for a
Collective Perception Service. The obtained results show the
proposed mechanism can contribute to improve the awareness of
crossing pedestrians at intersections by increasing the reliability
in the exchange of CPM messages between vehicles approaching
the intersection. This solution is being discussed under IEEE
802.11bd, and thus can be relevant for the standardization
process.10.13039/501100000780-European Commission;10.13039/501100007170-Ministry of Econom
On Byzantine Broadcast in Loosely Connected Networks
We consider the problem of reliably broadcasting information in a multihop
asynchronous network that is subject to Byzantine failures. Most existing
approaches give conditions for perfect reliable broadcast (all correct nodes
deliver the authentic message and nothing else), but they require a highly
connected network. An approach giving only probabilistic guarantees (correct
nodes deliver the authentic message with high probability) was recently
proposed for loosely connected networks, such as grids and tori. Yet, the
proposed solution requires a specific initialization (that includes global
knowledge) of each node, which may be difficult or impossible to guarantee in
self-organizing networks - for instance, a wireless sensor network, especially
if they are prone to Byzantine failures. In this paper, we propose a new
protocol offering guarantees for loosely connected networks that does not
require such global knowledge dependent initialization. In more details, we
give a methodology to determine whether a set of nodes will always deliver the
authentic message, in any execution. Then, we give conditions for perfect
reliable broadcast in a torus network. Finally, we provide experimental
evaluation for our solution, and determine the number of randomly distributed
Byzantine failures than can be tolerated, for a given correct broadcast
probability.Comment: 1
Formal proofs for broadcast algorithms
Standard distributed algorithmic solutions to recurring distributed problems are commonly specified and described informally. A proper understanding of these distributed algorithms that clarifies ambiguities requires formal descriptions. However, formalisation tends to yield complex descriptions. We formally study two broadcast algorithms and present an encoding framework using a process descriptive language and formalise these algorithms and their specifications using this framework. Following these new formal encodings we discuss correctness proofs for the same algorithms.peer-reviewe
Efficient simulation of view synchrony
This report presents an algorithm for efficiently simulating view synchrony, including failure-atomic total-order multicast in a discrete-time event simulator. In this report we show how a view synchrony implementation tailored to a simulated environment removes the need for third party middleware and detailed network simulation, thus reducing the complexity of a test environment. An additional advantage is that simulated view synchrony can generate all timing behaviours allowed by the model instead of just those exhibited by a particular view synchrony implementation
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