Proposed Hybrid Automatic Repeat Request Scheme Research Articles

Throughput Analysis of HARQ Scheme Based on Full-Duplex Two-Way AF SWIPT Relay

The simultaneous wireless information and power transfer (SWIPT) relay system is one of the emerging technologies. Xiaomi Corporation and Motorola Inc. recently launched indoor wireless power transfer equipment is one of the most promising applications. To tap the potential of the system, hybrid automatic repeat request (HARQ) is introduced into the SWIPT relay system. Firstly, the time slot structure of HARQ scheme based on full duplex two-way amplify and forward (AF) SWIPT relay is given, and its retransmission status is analyzed. Secondly, the equivalent signal-to-noise ratio and outage probability of various states are calculated by approximate simplification. Thirdly, the energy harvesting power in each state is calculated. Finally, the energy harvested-throughput sum function is constructed to characterize the performance of energy harvesting and data transmission. Simulation results show that the proposed HARQ scheme has better energy harvested-throughput sum function than the traditional HARQ scheme. When P2 = 22 dB, the maximum sum function is 54.86% (the proposed HARQ scheme) and 52.307% (the traditional HARQ scheme), respectively.

How to Boost the Throughput of HARQ With Off-the-Shelf Codes

In this paper, we propose a coding strategy designed to enhance the throughput of hybrid automatic repeat request (HARQ) transmissions over independent identically distributed block-fading channels with the channel state information unknown at the transmitter. We use a joint packet coding where the same channel block is logically shared among many packets. To reduce the encoding and decoding complexity, we use a two-layer coding where, first, packets are punctured, mixed, and then passed to the conventional channel encoder. We show how to optimize the puncturing rates on the basis of the empirical error-rate curves. We also discuss how the parameters of the practical turbo-codes may be modified to take advantage of the proposed HARQ scheme. Finally, simple and pragmatic rate adaptation strategies are developed. In numerical examples, our scheme is compared with the conventional incremental redundancy HARQ (IR-HARQ), which remains a strategy of choice in the region of small throughput; however, our scheme shows a notable gain of $1-2~\textrm {dB}$ in the region of high throughput, where IR-HARQ fails to provide any improvement.

Multiple retransmission strategy‐based HARQ for MIMO systems with acknowledgment bundling

A new hybrid automatic repeat request (HARQ) scheme is proposed for multiple-input multiple-output (MIMO) systems when the acknowledgment (ACK) bundling is applied for packet retransmissions. In the proposed HARQ scheme, both Chase combining (CC) and incremental redundancy (IR) are utilised for a retransmission request, and the proposed HARQ scheme is called a multiple retransmission strategy-based HARQ (MRS-HARQ). During the reception process of the MRS-HARQ, IR packets obtain signal-to-noise ratio gains using the extended detection with CC packets and the improved IR packets are utilised to eliminate the interference from the CC packets. This sequential reliability improvement allows the MRS-HARQ to decrease the occurrence of the deficient transmissions, and the proposed MRS-HARQ can achieve an improved error performance and throughput over the conventional CC-based and IR-based HARQ schemes with the ACK bundling.

A Hybrid ARQ Scheme Based on Polar Codes

A hybrid automatic repeat request (HARQ) scheme based on a novel class of rate-compatible polar (\mbox{RCP}) codes are proposed. The RCP codes are constructed by performing punctures and repetitions on the conventional polar codes. Simulation results over binary-input additive white Gaussian noise channels (BAWGNCs) show that, using a low-complexity successive cancellation (SC) decoder, the proposed HARQ scheme performs as well as the existing schemes based on turbo codes and low-density parity-check (LDPC) codes. The proposed transmission scheme is only about 1.0-1.5dB away from the channel capacity with the information block length of 1024 bits.

Hybrid ARQ Protocol for Multi-Antenna Multicasting Using a Common Feedback Channel

Wireless multicasting (also called common information broadcasting) is a technique where a common information message is transmitted to multiple users. This is typically accomplished by having the basestation broadcast out a signal representing this message. In this paper, we consider a multicasting scheme where the basestation transmits the multicasting signal without any a-priori knowledge of the users' channel state information. In this set-up, a hybrid automatic repeat request (ARQ) control is employed to improve the reliability of multicasting communication. In most hybrid ARQ set-ups, each user is usually allocated a dedicated feedback channel to tell the basestation if the previously transmitted signal was correctly decoded. However, dedicated feedback channels waste significant uplink resources, especially when the number of users is large. To mitigate this problem, we consider a negative acknowledgement (NACK) based hybrid ARQ control where the failed users are allowed to transmit the NACK signal (which is assumed to be the same for all users) through a common channel while the other users remain silent. We consider the effect of feedback error and multicasting signal decoding error on our hybrid ARQ system performance as the number of users grows large. Specifically, it is shown that the throughput performance of the proposed hybrid ARQ scheme using repetition retransmission is not severely degraded relative to the throughput performance of the noiseless feedback case. In addition, we show that the performance improvement obtained by replacing repetition encoding with incremental redundancy becomes insignificant for the large number of users asymptote. On the other hand, it is shown that the improvement provided by incremental redundancy is significant when some of the users are allowed to fail to decode the message.

An Evaluation on Throughput Performance for Type II Hybrid-ARQ Using Non-binary Rate-Compatible-Punctured LDPC Codes

In this letter, an NB RCP LDPC (Non-Binary Rate-Compatible-Punctured Low Density Parity Check) code has been designed over the extended Galois Field. The designed code enables us to change the code rate easily by properly puncturing the appropriate symbols from the LDPC mother code. The designed NB RCP LDPC code has been applied to the Type II HARQ (Hybrid Automatic Repeat reQuest) scheme using OFDM (Orthogonal Frequency Division Multiplexing) modulation. The throughput characteristics of the proposed HARQ scheme are evaluated through computation simulation.

A multi-CRC selective HARQ scheme for MIMO systems

A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR).

Hybrid ARQ scheme using interleaved Reed-Solomon codes in a power-controlled DS-CDMA cellular system

A new hybrid automatic repeat request (ARQ) scheme is proposed for data transmission in a power-controlled direct sequence (DS) code division multiple access (CDMA) system cellular system. The data frame is composed of interleaved Reed-Solomon codes. The depth of interleaving is determined by a power-control interval. After decoding each codeword with algebraic decoding, the post-decoding processor decides whether to accept the codeword or to discard it by using channel state information from the power-control processor. The proposed hybrid ARQ scheme significantly reduces the probability of undetected error among accepted codewords without significantly reducing the throughput.