Splitting algorithms for fast relay selection: Generalizations, analysis, and a unified view

IEEE Trans. Wireless Commun.

2010

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313

228

Abstract-The use of energy harvesting (EH) nodes as cooperative relays is a promising and emerging solution in wireless systems such as wireless sensor networks. It harnesses the spatial diversity of a multi-relay network and addresses the vexing problem of a relay's batteries getting drained in forwarding information to the destination. We consider a cooperative system in which EH nodes volunteer to serve as amplify-and-forward relays whenever they have sufficient energy for transmission. For a general class of stationary and ergodic EH processes, we introduce the notion of energy constrained and energy unconstrained relays and analytically characterize the symbol error rate of the system. Further insight is gained by an asymptotic analysis that considers the cases where the signal-to-noise-ratio or the number of relays is large. Our analysis quantifies how the energy usage at an EH relay and, consequently, its availability for relaying, depends not only on the relay's energy harvesting process, but also on its transmit power setting and the other relays in the system. The optimal static transmit power setting at the EH relays is also determined. Altogether, our results demonstrate how a system that uses EH relays differs in significant ways from one that uses conventional cooperative relays.

Section: Relay Selectionmentioning

confidence: 99%

Voluntary Energy Harvesting Relays and Selection in Cooperative Wireless Networks

Medepally¹,

IEEE Trans. Wireless Commun.

2010

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313

228

“…where α α α N−1 and F F F N−1 are defined in (6) and (7). Neglecting the event in which three nodes transmit, we get…”

Section: Proof Of Resultsmentioning

confidence: 99%

“…In the splitting scheme, nodes whose metrics lie between two thresholds transmit in a slot [6], [7]. The thresholds for the next slot are updated based on the outcome of the current slot.…”

Section: A Distributed Node Selection Schemesmentioning

confidence: 99%

Timer-Based Distributed Node Selection Scheme Exploiting Power Control and Capture

Dewangan

IEEE Trans. Wireless Commun.

2015

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Abstract-Opportunistic selection in multi-node wireless systems improves system performance by selecting the "best" node and by using it for data transmission. In these systems, each node has a real-valued local metric, which is a measure of its ability to improve system performance. Our goal is to identify the best node, which has the largest metric. We propose, analyze, and optimize a new distributed, yet simple, node selection scheme that combines the timer scheme with power control. In it, each node sets a timer and transmit power level as a function of its metric. The power control is designed such that the best node is captured even if η other nodes simultaneously transmit with it. We develop several structural properties about the optimal metric-to-timer-and-power mapping, which maximizes the probability of selecting the best node. These significantly reduce the computational complexity of finding the optimal mapping and yield valuable insights about it. We show that the proposed scheme is scalable and significantly outperforms the conventional timer scheme. We investigate the effect of η and the number of receive power levels. Furthermore, we find that the practical peak power constraint has a negligible impact on the performance of the scheme.

“…Distributed selection schemes successfully tackle this problem [2], [5]- [8]. One prominent example is the time-slotted splitting-based selection scheme [6], [7]. In it, all nodes whose metrics lie in between…”

Section: Introductionmentioning

confidence: 99%

Feedback Overhead-Aware Fast Distributed Selection Scheme for Multi-Node Wireless Systems

Talak

2011 IEEE Global Telecommunications Conference - GLOBECOM 2011

2011

Abstract-Opportunistic selection is a practically appealing technique that is used in multi-node wireless systems to maximize throughput, implement proportional fairness, etc. However, selection is challenging since the information about a node's channel gains is often available only locally at each node and not centrally. We propose a novel multiple access-based distributed selection scheme that generalizes the best features of the timer scheme, which requires minimal feedback but does not always guarantee successful selection, and the fast splitting scheme, which requires more feedback but guarantees successful selection. The proposed scheme's design explicitly accounts for feedback time overheads unlike the conventional splitting scheme and guarantees selection of the user with the highest metric unlike the timer scheme. We analyze and minimize the average time including feedback required by the scheme to select. With feedback overheads, the proposed scheme is scalable and considerably faster than several schemes proposed in the literature. Furthermore, the gains increase as the feedback overhead increases.