On Power Allocation for Incremental Redundancy Hybrid ARQ

In this work, we develop low complexity, optimal power allocation algorithms that would allow ultra reliable operation at any outage probability target with minimum power consumption in the finite blocklength regime by utilizing Karush-Kuhn-Tucker (KKT) conditions. In our setup, we assume that the transmitter does not know the channel state information (CSI). First, we show that achieving a very low packet outage probability by using an open loop setup requires extremely high power consumption.Thus, we resort to retransmission schemes as a solution, namely Automatic Repeat Request (ARQ), Chase Combining Hybrid ARQ (CC-HARQ) and Incremental Redundancy (IR) HARQ. Countrary to classical approaches, where it is optimal to allocate equal power with each transmission, we show that for operation in the ultra reliable regime (URR), the optimal strategy suggests transmission with incremental power in each round. Numerically, we evaluate the power gains of the proposed protocol. We show that the best power saving is given by IR-HARQ protocol. Further, we show that when compared to the one shot transmission, these protocols enable large average and maximum power gains. Finally, we show that the larger the number of transmissions is, the larger power gains will be attained.

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“…To compute the power allocation algorithm, again we resort to problem (15). First, we write the Lagrangian function as…”

Section: Appendix Fmentioning

confidence: 99%

Ultra reliable communication via optimum power allocation for type-I ARQ in finite block-length

Dosti

Wijewardhana

Alves

et al. 2017

2017 IEEE International Conference on Communications (ICC)

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“…Without fairness constraint, the joint optimization of the power and rate would aggressively allocate most of power to the user with better channel condition, which behaves like waterfilling algorithm regardless of user fairness [40] and violates the intention of NOMA protocol [11]- [14]. This interesting phenomenon can be observed in Table I for the proposed scheme, where the notation "−" denotes no feasible solution.…”

Section: Maximization Of Ltatmentioning

confidence: 96%

Cooperative HARQ-Assisted NOMA Scheme in Large-Scale D2D Networks

Shi

ElSawy

et al. 2018

IEEE Trans. Commun.

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This paper develops an interference aware design for cooperative hybrid automatic repeat request (HARQ) assisted non-orthogonal multiple access (NOMA) scheme for large-scale device-to-device (D2D) networks. Specifically, interference aware rate selection and power allocation are considered to maximize long term average throughput (LTAT) and area spectral efficiency (ASE). The design framework is based on stochastic geometry that jointly accounts for the spatial interference correlation at the NOMA receivers as well as the temporal interference correlation across HARQ transmissions. It is found that ignoring the effect of the aggregate interference, or overlooking the spatial and temporal correlation in interference, highly overestimates the NOMA performance and produces misleading design insights. An interference oblivious selection for the power and/or transmission rates leads to violating the network outage constraints. To this end, the results demonstrate the effectiveness of NOMA transmission and manifest the importance of the cooperative HARQ to combat the negative effect of the network aggregate interference. For instance, comparing to the non-cooperative HARQ assisted NOMA, the proposed scheme can yield an outage probability reduction by 32%. Furthermore, an interference aware optimal design that maximizes the LTAT given outage constraints leads to 47% throughput improvement over HARQ-assisted orthogonal multiple access (OMA) scheme.

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“…A function is convex if both the objective function and the constraint set are convex. Based on (11), (14), (38) and (43) it is straightforward to show that proving the convexity of our problem reduces to proving the convexity of…”

Section: Appendix a Proof Of Lemmamentioning

confidence: 99%

“…All these schemes boost reliability at the cost of increased latency and complexity of the receiver design. In addition, several retransmission protocols utilize parallel coding schemes, where they utilize Incremental redundancy (IR) [14]. Therein, the transmitter sends new information with each retransmission.…”

Section: Introductionmentioning

confidence: 99%

Ultra Reliable Communication via Optimum Power Allocation for HARQ Retransmission Schemes

2020

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In this work, we develop low complexity, optimal power allocation algorithms that would allow ultra reliable operation at any outage probability target with minimum power consumption in the finite blocklength regime by utilizing Karush-Kuhn-Tucker (KKT) conditions. In our setup, we assume that the transmitter does not know the channel state information (CSI). First, we show that achieving a very low packet outage probability by using an open loop setup requires extremely high power consumption. Thus, we resort to retransmission schemes as a solution, namely Automatic Repeat Request (ARQ), Chase Combining Hybrid ARQ (CC-HARQ) and Incremental redundancy (IR) HARQ. Countrary to classical approaches, where it is optimal to allocate equal power with each transmission, we show that for operation in the ultra reliable regime (URR), the optimal strategy suggests transmission with incremental power in each round. Numerically, we evaluate the power gains of the proposed protocol. We show that the best power saving is given by IR-HARQ protocol. Further, we show that when compared to the one shot transmission, these protocols enable large average and maximum power gains. Finally, we show that the larger the number of transmissions is, the larger power gains will be attained.

show abstract

On Power Allocation for Incremental Redundancy Hybrid ARQ

Cited by 10 publications

References 21 publications

Ultra reliable communication via optimum power allocation for type-I ARQ in finite block-length

Ultra reliable communication via optimum power allocation for type-I ARQ in finite block-length

Cooperative HARQ-Assisted NOMA Scheme in Large-Scale D2D Networks

Ultra Reliable Communication via Optimum Power Allocation for HARQ Retransmission Schemes

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