Max-Consensus Over Fading Wireless Channels
Abstract : This paper deals with the problem of achieving finite-time max-consensus in a multi-agent system that communicates over a fading wireless channel. A key feature of the wireless channel is the superposition (or broadcast) property. In traditional wireless communication systems, the superposition property is usually undesired since it might cause interference that drastically degrades system performance. In contrast, in the multi-agent system considered in this paper, different agents aim at achieving max-consensus. Therefore, rather than combatting interference due to the superposition property, we design a communication system that exploits this property for a more efficient usage of wireless resources. By simultaneously accessing the wireless channel, each agent obtains a weighted average of the neighboring agents' information states, where weights (namely, channel coefficients) are unknown and fading. Given that each agent has access to this piece of information, we present a switching consensus protocol employing broadcast autorisations for agents and show that max-consensus can be achieved under this protocol within a finite number of iterations.
? While there exists a rich literature on estimation consensus, detection consensus problems only recently started to receive attention.
? They consider the case where each node transmits its belief (conditional probability) to other nodes. As a result, their problem immediately takes the form of the traditional average estimation consensus for which a rich literature exists.
? We first discuss the fusion and diversity decision-making strategies over time-invariant network topologies and shed light on the underlying trade-offs.
? In this paper, we are interested in group agreement problem, where a group of agents need to reach consensus on the value of a parameter of interest.
? In the classical distributed estimation problem, sensors make noisy observations of a scalar.
? The basic consensus problem addresses the convergence of such schemes. Centralized approaches require the computation of a tree, rooted at the fusion node, aggregation of data up the tree, and dissemination of the consensus value down the tree.
? This may be achieved if nodes have multipacket reception capability , or proper scheduling is performed. We illustrate the impact of collisions.
? Consensus over fading channels and the issue of deterministic vs. random schedules has been considered in and. We consider an Aloha based approach and compare performance to that of tree-based approaches.
• In and, the consensus problem and event-triggered communication strategy in MASs are analyzed, and in the proposed method is applied to a vehicle platoon control.
• We mathematically analyze the proposed framework and show how the network achieves accurate consensus asymptotically.
• To show an example, we then utilize the proposed framework over regular ring lattice networks.
• Our theoretical and simulation results indicate that the proposed technique improves the consensus performance considerably.
• We proposed a novel consensus-seeking protocol that utilizes information of link qualities. We showed that by incorporating the information of link qualities, the network will be in consensus with a higher probability but still holds the undesirable asymptotic behavior.
? Therefore, the design of consensus protocols aiming at exploiting interference and, as a consequence, allowing a more efficient use of wireless resources, has recently attracted attention.
? Adopting orthogonal transmission (thus avoiding interference) is therefore not necessary, which motivates a more efficient method to achieve the same goal by exploiting the interference.
? The fading effect attenuates by a random (and unknown) coefficient all transmitted signals. The receiver obtains a superposition (sum) of such attenuated signals.
? The fading channel coefficients are assumed to be positive real numbers.
? The fading channel coefficients are assumed to be identically distributed and independent across different iterations and across different transmitter-receiver pairs.
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