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32
Coding versus ARQ in fading channels: how reliable should the PHY be?,” GLOBECOM’09
, 2009
"... Abstract—This paper studies the tradeoff between channel coding and ARQ (automatic repeat request) in Rayleigh blockfading channels. A heavily coded system corresponds to a low transmission rate with few ARQ retransmissions, whereas lighter coding corresponds to a higher transmitted rate but more re ..."
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Cited by 29 (6 self)
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Abstract—This paper studies the tradeoff between channel coding and ARQ (automatic repeat request) in Rayleigh blockfading channels. A heavily coded system corresponds to a low transmission rate with few ARQ retransmissions, whereas lighter coding corresponds to a higher transmitted rate but more retransmissions. The optimum error probability, where optimum refers to the operating point that maximizes the average successful throughput, is derived and is shown to be a decreasing function of the average signaltonoise ratio and of the channel diversity order. A general conclusion of the work is that the optimum error probability is quite large (e.g., 10 % or larger) for reasonable channel parameters, and that operating at a very small error probability can lead to a significantly reduced throughput. I.
Outageoptimal power allocation for hybrid ARQ with incremental redundancy
 IEEE Trans. Wireless Commun
, 2011
"... AbstractWe consider the optimization of power in incremental redundancy (IR) based hybrid automatic repeat request (HARQ) schemes when the maximum number of (re)transmissions is fixed. We formulate two optimization problems: (i) minimizing the packet drop probability (PDP) under a total average tr ..."
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Cited by 9 (2 self)
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AbstractWe consider the optimization of power in incremental redundancy (IR) based hybrid automatic repeat request (HARQ) schemes when the maximum number of (re)transmissions is fixed. We formulate two optimization problems: (i) minimizing the packet drop probability (PDP) under a total average transmit power constraint, and (ii) minimizing the average transmit power under a fixed PDP constraint. We consider in detail the special case of only two allowed transmissions, and we prove that the two optimization problems are equivalent. For this special case, we also provide a suboptimal rootfinding solution and compare its performance with the optimal solution obtained through an exhaustive search. The results show that the optimal power allocation can provide significant gains over the equal power solution in terms of average transmit power spent. The performance of the proposed rootfinding solution is practically the same as that of the optimal solution. Index TermsHybrid ARQ, incremental redundancy, optimal power allocation, outage probability.
Outage Capacity of Incremental Relaying at Low SignaltoNoise Ratios
, 908
"... Abstract—We present the ǫoutage capacity of incremental relaying at low signaltonoise ratios (SNR) in a wireless cooperative network with slow Rayleigh fading channels. The relay performs decodeandforward and repetition coding is employed in the network, which is optimal in the low SNR regime. ..."
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Cited by 7 (4 self)
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Abstract—We present the ǫoutage capacity of incremental relaying at low signaltonoise ratios (SNR) in a wireless cooperative network with slow Rayleigh fading channels. The relay performs decodeandforward and repetition coding is employed in the network, which is optimal in the low SNR regime. We derive an expression on the optimal relay location that maximizes the ǫoutage capacity. It is shown that this location is independent of the outage probability and SNR but only depends on the channel conditions represented by a pathloss factor. We compare our results to the ǫoutage capacity of the cutset bound and demonstrate that the ratio between the ǫoutage capacity of incremental relaying and the cutset bound lies within 1 / √ 2 and 1. Furthermore, we derive lower bounds on the ǫoutage capacity for the case of K relays.
Hybrid ARQ in MultipleAntenna Slow Fading Channels: Performance Limits and Optimal Linear Dispersion Code Design
, 2009
"... This paper focuses on studying the fundamental performance limits and linear dispersion code design for the MIMOARQ slow fading channel. Optimal average rate of wellknown HARQ protocols is analyzed. The optimal design of spacetime coding for the MIMOARQ channel is discussed. Informationtheoreti ..."
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Cited by 6 (0 self)
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This paper focuses on studying the fundamental performance limits and linear dispersion code design for the MIMOARQ slow fading channel. Optimal average rate of wellknown HARQ protocols is analyzed. The optimal design of spacetime coding for the MIMOARQ channel is discussed. Informationtheoretic measures are used to optimize the rate assignment and derive the optimum design criterion, which is then used to evaluate the optimality of existing spacetime codes. A different design criterion, which is obtained from the error probability analysis of spacetime coded MIMOHARQ, is presented. Examples are studied to reveal the gain of ARQ feedback in spacetime coded MIMO systems.
Novel approximations to the statistics of products of independent random variables and their applications in wireless communications. Vehicular Technol
 IEEE Trans
, 2012
"... Abstract—A novel analytical framework for evaluating the statistics of the product of independent random variables is proposed. Compared with other methods, which use either infinite series or special functions, the new method provides simple and efficient closedform approximations, in terms of el ..."
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Cited by 5 (1 self)
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Abstract—A novel analytical framework for evaluating the statistics of the product of independent random variables is proposed. Compared with other methods, which use either infinite series or special functions, the new method provides simple and efficient closedform approximations, in terms of elementary functions, such as powers and exponentials. Numerical results, which are used to check the accuracy of the new approximations, show that it is quite accurate in most regions of interest. As an application, the proposed analytical results can be efficiently used in wireless communications theory to evaluate in closed form the outage probability of cascaded fading channels, as well as the rate offset of the hybrid automatic repeat request (HARQ) transmission. Numerical examples show that the derived expressions provide significant insights on the behaviors of important system parameters as the outage probability and the rate offset. Index Terms—Cascaded fading channels, keyhole channels, product of random variables (RVs), wireless communications, wireless relaying. I.
On the energy delay tradeoff of HARQIR in wireless multiuser systems
 IEEE Trans. Commun
, 2013
"... Abstract—Energy delay tradeoff (EDT) is a fundamental tradeoff that plays a crucial role in understanding the energy efficiency of various transmission schemes. In particular, for hybrid automatic repeat request (HARQ) protocols, the EDT can be well defined. In this paper, in order to understand the ..."
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Cited by 1 (0 self)
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Abstract—Energy delay tradeoff (EDT) is a fundamental tradeoff that plays a crucial role in understanding the energy efficiency of various transmission schemes. In particular, for hybrid automatic repeat request (HARQ) protocols, the EDT can be well defined. In this paper, in order to understand the EDT for a wireless multiuser system, we consider various downlink transmission schemes where the HARQ with incremental redundancy (HARQIR) protocol is employed for reliable transmissions to users. For a given total power, the impact of different transmission schemes in conjunction with power allocation on EDT is extensively studied. Among the transmission schemes, it is shown that the thresholdbased transmission (TBT) scheme efficiently lowers the minimum energy per bit (EB) in spite of limited prior channel state information (CSI) feedback. The study is further extended to a more plausible scenario where users have different channel statistics. In doing so, we consider a proportional fairness scheduling based on relative channel gain that can be easily accommodated in the proposed TBT scheme, and study its EDT behaviors. Performance evaluations show that the schemes incorporating proportional fairness achieve good EDT performances while guaranteeing the fairness among users. Index Terms—Energy efficiency, hybrid automatic repeat request (HARQ), power allocation. I.
RECEIVER DESIGN AND SECURITY FOR LOW POWER
, 2014
"... This Open Access Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has ..."
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This Open Access Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has
1On Hybrid ARQ and Quantized CSI Feedback Schemes in QuasiStatic Fading Channels
"... This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: IEEE transaction on communications (ISSN: 00906778) Citation for the published paper: ..."
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This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: IEEE transaction on communications (ISSN: 00906778) Citation for the published paper:
Chalmers Publication Library
"... Reinforcementbased data transmission in temporallycorrelated fading channels: Partial CSIT scenario This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: ..."
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Reinforcementbased data transmission in temporallycorrelated fading channels: Partial CSIT scenario This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: