Buffering in a Three-Node Relay Network

Bing, Xia; Fan, Yalin; Thompson, J. S.; Poor, H. Vincent

doi:10.1109/t-wc.2008.070867

Cited by 169 publications

(135 citation statements)

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“…However, despite the efficient use of the channel fading and the related performance benefits, the max − max relay selection policy requires a predefined schedule for the relaying transmission (e.g., the second slot is always allocated for relaying) and therefore the available diversity degrees are not fully exploited. It is worth noting that the use of buffers in order to boost the achieved performance (in terms of throughput) has been reported in the literature in different contexts ( [4]- [7] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Opportunistic relay selection for cooperative networks with secrecy constraints

2010

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Abstract-In this paper, a relay selection policy is proposed that fully exploits the flexibility offered by the buffering ability of the relay nodes in order to maximize the achieved diversity gain. The suggested scheme incorporates the instantaneous strength of the wireless links as well as the status of the finite relay buffers and adapts the relay selection decision on the strongest available link by dynamically switching between relay reception and transmission. We show that the proposed relay selection scheme significantly outperforms conventional relay selection policies for all cases and ensures a diversity gain equal to two times the number of relays for large buffer sizes. I. INTRODUCTIONWe focus on a simple decode-and-forward (DF) cooperative network where a source communicates with a destination through a set of half-duplex relay nodes with the objective of performance optimisation. For this fundamental problem, the max − min relay selection scheme [1], [2], where the selected relay holds the strongest end-to-end relaying path, achieves the optimal performance and ensures a full diversity equal to the number of the relays. However, this relay selection policy refers to a two-slot cooperative transmission where the selected relay receives the source's data during the first time slot and immediately in the next time slot forwards the data towards the destination. In order to overcome this limitation imposed by the max − min selection scheme, recently in [3] the authors introduced data buffers at the relay nodes that allow the selection of a different relay for reception and transmission in order to extract further diversity gains. In that work, the max − max relay selection scheme that selects the relay with the strongest source-relay channel and the strongest relaydestination channel for reception and transmission, respectively, has been investigated. The max − max scheme refers to applications without critical delay constraints and provides a significant coding gain in comparison to the conventional max − min selection scheme. However, despite the efficient use of the channel fading and the related performance benefits, the max − max relay selection policy requires a predefined schedule for the relaying transmission (e.g., the second slot is always allocated for relaying) and therefore the available diversity degrees are not fully exploited. It is worth noting that the use of buffers in order to boost the achieved performance (in terms of throughput) has been reported in the literature in different contexts ( [4]-[7] and references therein).

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Section: Introductionmentioning

confidence: 99%

Opportunistic relay selection for cooperative networks with secrecy constraints

2010

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“…Recent works have introduced buffer-aided relaying, where the relay employs buffer to store the received data from the source for future forwarding to the destination [43], [44]. Under buffer-aided relaying, the relay has more transmission flexibility since it might not need to forward the received data to the destination immediately after receiving it as in the case of fixed relaying.…”

Section: Half-duplex Relaying With Adaptive Link Selectionmentioning

confidence: 99%

“…Consider a simple 3-node source-relay-destination relaying system. Recently, the works [43], [44] introduce the idea of buffer-aided relaying, where the relay employs buffer to store the received data from the source for future transmission to the destination. Thanks to the buffer-aided relaying capability, adaptive link selection relaying is possible, where either the source-relay link or the relay-destination link is active depending on the channel state information (CSI) in each transmission frame [45]- [47].…”

Section: Introductionmentioning

confidence: 99%

“…Thanks to the buffer-aided relaying capability, adaptive link selection relaying is possible, where either the source-relay link or the relay-destination link is active depending on the channel state information (CSI) in each transmission frame [45]- [47]. While adaptive relaying is able to exploit the link fading diversity, one disadvantage is the (queueing) delay incurred at the relay buffer, which is assumed to be unconstrained or under average delay constraint in existing works [43]- [47]. Alternatively, in Chapter 5, we study the optimal adaptive relaying problem under delay-outage constraint.…”

Section: Introductionmentioning

confidence: 99%

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Radio Resource Allocation Over Fading Channels Under Statistical Delay Constraints

Phan¹,

Le‐Ngoc²

2017

SpringerBriefs in Electrical and Computer Engineering

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Wireless data transmission suffers from the fading nature of wireless channels, where the instantaneous channel conditions and hence transmission rates randomly fluctuate over time. Consequently, data arrivals at each transmitter might not be transmitted instantly. To cope with this situation, the transmitter employs buffer to store the data temporarily for later transmission. While data buffering enables more efficient radio resource allocation to opportunistically select the favorable fading conditions for transmission, it introduces queuing delay that needs to be controlled in order to meet the end-to-end delay quality-ofservice (QoS) requirements in supporting delay-sensitive communications. In this thesis, we study and develop radio resource allocation schemes for buffer-aided communications over wireless fading channels under statistical delay constraints. Using the buffering capability as a means to exploit the fading diversity, the nodes (source and relay) perform resource allocation, and adapt their transmissions to the channel state information (CSI) in order to enhance the system throughput while maintaining the statistical delay QoS requirements in terms of upper-bounded average delay or delay-outage probability.The thesis starts by considering a source-destination communications link over a fading channel with data arriving at the source transmission buffer. In the first scenario, the source is assumed to have a maximum power constraint and an average delay constraint. We consider admission control applied on random data arrivals to the source buffer in order to avoid constraint violation, and study the joint optimal data admission control and power allocation (AC-PA) problem for throughput maximization. In the second scenario, we consider an energy-harvesting (EH) source, where random amounts of energy are harvested from renewable energy sources, and stored in a battery during the course of data transmission. In every transmission time slot, the source is constrained to use at most the amount of energy currently stored. We then explore optimal power allocation problems for such EH systems under average delay or delay-outage constraints. We formulate the problems as infinite horizon constrained Markov decision process (MDP) problems, which incorporate the random variations of the fading channel, data arrival, and EH processes. A novel solution approach based on post-decision state-value function is proposed to study the properties of the optimal solutions. We also propose online allocation algorithms when the statistical knowledge of the random processes is unknown, which is typical in real-life communications. Illustrative results demonstrate the effectiveness of the proposed algorithms over existing approaches iii under similar power and delay constraints.The thesis continues with a source-relay-destination communications link over fading channels with buffers available at both source and relay, as part of a multi-hop network. We investigate and develop optimal resource allocation schemes ...

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“…By adding buffers to relays it is increased the spectral efficiency of the systems. Because of better understanding, firstly, we will consider a relay network with three nodes [3]- [4]. So, there is a source of information, a relay that is equipped with a buffer, and a destination.…”

Section: Introductionmentioning

confidence: 99%