Performance Analysis of a Memory ARQ Scheme with Soft Decision Detectors

We propose and analyze a scheme for wireless channels, which is a combination of a hybrid type I automatic repeat request (ARQ) scheme and a power ramping. In the hybrid type I ARQ scheme, the same redundancy bits for error correction is transmitted repeatedly when a negative acknowledgment (NAK) is obtained. In addition to the ARQ scheme, the power ramping is considered for more reliable downlink data transmission, in which the transmission power is gradually changed from a small level to large levels when the number of retransmission increases. This is done without any knowledge of the channels at the transmitter. Simulation results show that by applying the combined hybrid ARQ and power ramping scheme with properly selected parameters, it has a throughput advantage of 3-5%.

Various Automatic Repeat Request (ARQ) schemes have been used to combat errors that befall information transmitted in digital communication systems. Such schemes include simple ARQ, mixed mode ARQ and Hybrid ARQ (HARQ). In this study we introduce extended ARQ schemes and derive expressions for their throughput performance. We then compare their performance with mixed mode ARQ schemes where it is shown that extended ARQ schemes outperform the mixed mode ARQ schemes. We also show how the parameters for the schemes can be chosen to maximize performance.Keywords: ARQ, extended ARQ, HARQ, mixed mode ARQ, throughput

In an automatic repeat request (ARQ) scheme, a packet is retransmitted if it gets corrupted due to transmission errors caused by the channel. Here we describe a ready-to-implement ARQ scheme with packet combining. An analytical description of the scheme in random error channel shows excellent agreement with simulation results. An upper bound for type-II schemes is defined. For smaller packet sizes, throughput of the proposed scheme is sufficiently close to the upper bound till a very high bit error rate.

Sequential decoding is analyzed in conjunction with an efficient incremental redundancy automatic repeat request (ARQ) scheme using punctured convolutional coding. With the incremental redundancy ARQ scheme, whenever the decoding time of a given data packet exceeds some predetermined value T/sub max/, decoding of that data packet is stopped and incremental redundancy bits are provided by the transmitter, a few bits at a time, as needed. It is shown that the incremental redundancy ARQ scheme provides throughput improvement over the partial retransmission code combining ARQ scheme. The advantage of the incremental redundancy ARQ scheme is that the throughput increases as the starting coding rate increases over all ranges of signal-to-noise ratios. >

Power-line communication (PLC) networks have been increasingly used for constructing industrial IoT (internet of things) and home networking systems due to their low-cost installation and broad coverage feature. To guarantee the transmission reliability, ARQ (automatic repeat request) scheme is introduced into the link layer of reliable PLC networks, which allows the retransmission of a data frame several times so that it has a higher probability to be correctly received. However, current studies of performance analysis for PLC MAC (medium access control) protocol (i.e., IEEE 1901) do not take into account of the impact of ARQ scheme. To resolve this problem, we propose an analytical model to investigate the MAC performance of IEEE 1901 protocol for reliable PLC networks with ARQ scheme. In the modeling process, we first establish a PLC channel model to reflect the impacts of PLC channel types (containing Rayleigh fading and Log-normal fading), additive non-Gaussian noise feature and ARQ scheme on data transmission at link layer. Next, we employ Renewal theory and Queueing dynamics to capture the transmission attempt behavior of executing IEEE 1901 protocol in the unsaturated environment with finite transit buffer size. On the basis of combining these two models, we derive the closed-form expressions of 1901 MAC metrics considering the influence of the ARQ scheme. Furthermore, we prove that the proposed analytical model has the convergence property. Finally, we evaluate the MAC performance of 1901 protocol for reliable PLC networks with ARQ scheme and verify the proposed analytical model.

This paper proposes a new automatic repeat request (ARQ) scheme for reliable broadcasting in distributed wireless LANs. Unlike traditional ARQ schemes for reliable broadcasting, the proposed scheme is highly efficient in its ARQ control information delivery and only introduces light control overhead in the network. Our simulation results show that as compared with traditional ARQ schemes, the proposed scheme improves the LAN throughput by from several tens to more than one hundred percent, depending on the number of nodes in the LAN.

An adaptive control procedure is proposed for the go-back-N and selective-repeat automatic repeat-request (ARQ) schemes. The procedure is to dynamically vary the number and length of continuously transmitted data blocks according to the bit error rate. The throughput of the adaptive ARQ schemes for a half-duplex transmission line is compared with the throughput of corresponding conventional schemes. Numerical results indicate that adaptive ARQ schemes are superior to conventional ARQ schemes when the bit error rate is not known or varies with time.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new hybrid automatic repeat request (ARQ) scheme that utilises reliability estimates generated by soft-input, soft-output (SISO) decoders is proposed. The proposed ARQ scheme transmits additional information for the unreliable bits, and this information is used to perform additional decoding. Results are presented that show this ARQ technique can provide performance close to the channel capacity.

A type-1 hybrid automatic-repeat-request (ARQ) scheme with time diversity combining is proposed and its performance analysed for binary digital FM (BFM) mobile radio communications. Time diversity combining is achieved by exploiting the packet retransmission nature inherent in the ARQ scheme. The ARQ scheme employs a high-rate error-correcting code with either hard-decision decoding or soft-decision decoding. Received signal envelopes are sampled and used as channel state information (CSI) in the decoding process. Numerical results on the system throughput and decoded bit error rate (BER) are presented as functions of average information signal-to-noise ratio, average information signal-to-interference ratio, and random FM noise.

A cooperative automatic repeat request (ARQ) scheme is proposed for cognitive radio networks with full duplex capability. Its performance is studied for ARQ and hybrid ARQ (HARQ) modes, in terms of data link layer packet error rate (PER) and the primary and secondary throughputs. It is shown that activity of the secondary network during primary’s retransmission does not affect primary’s performance in ARQ mode, and would even improve it in HARQ mode.

Adaptive stop-and-wait ARQ strategy for mobile data communications

Due to limited buffer space available at routers, the packets in the Internet gets lost or dropped, especially when the network is congested. Automatic repeat request (ARQ), is an error-control method that uses acknowledgments and timeouts to decide retransmission of messages to achieve reliable data transmission. However, the re-transmission of a lost packet further increases the congestion in the network, and hence the end-to-end delay of other coexisting flows. This paper aims at improving the performance of ARQ schemes by introducing a lightweight re-transmission mechanism called LW-ARQ based on the concept of caching of packets at intermediate routers that are indented to be dropped. To evaluate the performance of proposed LW-ARQ scheme, we chose to implement it over TCP protocol considering that TCP has become a de-facto transport layer protocol standard for the Internet. However, the proposed LW-ARQ scheme can be integrated with any protocol that uses either stop-and-wait or sliding window based ARQ scheme to handle packet losses. On analyzing the results obtained by performing simulations, we found that the proposed LW-ARQ scheme improves the average end-to-end delay performance of the TCP protocol.

User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the\ncore of high rate data-oriented downlink schemes of the next-generation of\ncellular systems (e.g., LTE-Advanced). Scheduling selects groups of users\naccording to their channels vector directions and SINR levels. However, when\nscheduling is applied independently in each cell, the inter-cell interference\n(ICI) power at each user receiver is not known in advance since it changes at\neach new scheduling slot depending on the scheduling decisions of all\ninterfering base stations. In order to cope with this uncertainty, we consider\nthe joint operation of scheduling, MU-MIMO beamforming and Automatic Repeat\nreQuest (ARQ). We develop a game-theoretic framework for this problem and build\non stochastic optimization techniques in order to find optimal scheduling and\nARQ schemes. Particularizing our framework to the case of "outage service\nrates", we obtain a scheme based on adaptive variable-rate coding at the\nphysical layer, combined with ARQ at the Logical Link Control (ARQ-LLC). Then,\nwe present a novel scheme based on incremental redundancy Hybrid ARQ (HARQ)\nthat is able to achieve a throughput performance arbitrarily close to the\n"genie-aided service rates", with no need for a genie that provides\nnon-causally the ICI power levels. The novel HARQ scheme is both easier to\nimplement and superior in performance with respect to the conventional\ncombination of adaptive variable-rate coding and ARQ-LLC.\n

We introduce an analytical method that uses a finite-state Markov chain (FSMC) as an error model, for estimating the performance of adaptive modulation systems (AMSs) combined with automatic repeat request (ARQ) schemes in correlated slow fading channels. For the throughput performance evaluation of wireless packet networks, conventionally, we have assumed independent block fading, which may also be suitable to represent fast fading channels. However, in slow fading channels, error rates of consecutive packets are highly correlated and we cannot simply assume independent error structure in performance evaluations. We propose a multistate Markov error structure for AMS in correlated fading channels, which is also described by a finite-state Markov chain (FSMC) and we also present throughput-estimation methods for AMS combined with ARQ, using the proposed Markov error structure.

Adaptive ARQ (automatic repeat request) is an error‐control scheme in data transmission in which the number of successively transmitted data blocks and the data block length are adjusted according to the bit error rate. This scheme performs better in half‐duplex transmission than the conventional selective repeat (SR) and go‐back‐N (GBN) schemes when the bit error rate is either not known or varies with time.This paper proposes a control procedure for the full‐duplex adaptive ARQ scheme. In this procedure an observation period is defined and the data block length is adjusted dynamically according to the success of the data block transmission in the observation period. The throughput of this scheme is analyzed. The proposed scheme is compared with nine conventional schemes, including SR and GBN, in terms of performance. The results indicate that the performance of the adaptive ARQ scheme is very close to that of the fixed data block scheme in which the optimal data block length is selected statically. It is also shown that the performance of the adaptive ARQ scheme does not degrade as rapidly as in other schemes when the bit error rate increases.