A New ARQ Scheme for Reliable Broadcasting in Wireless LANs

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

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. >

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.

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.

An automatic repeat-request (ARQ) scheme with memory and soft error detectors has been recently proposed by Benelli. Its performance was studied mainly through computer simulation. In this paper, a generalized version of this ARQ scheme is examined. The selection of certain thresholds and weights to minimize the bit error rate in systems using a fixed number of packet repeats is considered. Finally, the evaluation of the average number of transmissions per packet in systems in which negatively acknowledged packets are retransmitted until successfully received is described.

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.

In this paper1, we investigate different practical automatic repeat request (ARQ) retransmission protocols for twowaywireless relay networks based on network coding (NC). Theidea of NC is applied to increase the achievable throughput for the exchange of information between two terminals through one relay. Using NC, throughput efficiency is significantly improved due to the reduction of the number of retransmissions. Particularly, two improved NC-based ARQ schemes are designed based on go-back-N and selective-repeat (SR) protocols. The analysis of throughput efficiency is then carried out to find the best retransmission strategy for different scenarios. It is shown that the combination of improved NC-based SR ARQ scheme in the broadcast phase and the traditional SR ARQ scheme in themultiple access phase achieves the highest throughput efficiency compared to the other combinations of ARQ schemes. Finally, simulation results are provided to verify the theoretical analysis.

The quality of service (QoS) support in wireless local area networks (WLANs) faces a big challenge due to time-correlated fading channel. Conventional automatic repeat reQuest (ARQ) schemes based on time diversity may result in consecutive retransmission failures degrading QoS severely. This paper proposes a novel Differentiated cooperative medium access control (MAC) protocol, called DC-MAC, to enhance QoS in WLANs based on the IEEE 802.11e architecture. The retransmission is initiated from an appropriate transmission queue of an appropriate relay node instead of the original source to exploit spatial diversity. A novel negative acknowledgement (NAK) feedback mechanism is introduced for loss distinguishing and channel estimation such that cooperative retransmission will be employed only when necessary and only by competent nodes. Simulations conducted on the OPNET platform show that the proposed scheme significantly improves the performances of both multimedia applications and data applications in terms of throughput and delay while supporting service differentiation.

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.

In Wireless LANs MAC layer multicast error control schemes lead to shorter delays compared with application layer schemes. In this paper, we enhance a Leader Based Protocol (LBP) and propose a Beacon-driven Leader Based Protocol (BLBP) for the MAC layer multicast error control. Like LBP, BLBP selects one of the multicast group receivers as the leader and allows acknowledgement and negative acknowledgements from the leader receiver and non-leader receivers respectively. The use of the beacon frame is to lead the non-leader receivers to set timers and to announce the sequence number of the following data frame. Thanks to the sequence check based on the beacon frame, BLBP avoids the unnecessary transmissions in LBP. Both the theoretical analysis and simulation experiments show that BLBP can correct nearly all the errors for all receivers in the MAC layer and is more efficient than LBP. BLBP is even more efficient than the application layer automatic repeat request (ARQ) scheme and the total multicast delay is much shorter. BLBP is very good for real-time multicast applications with strict delay constraints.

A new efficient ARQ scheme for satellite communications

We introduce an automatic repeat request (ARQ) scheme that uses nonuniform signal constellations in order to adapt the data rate to the received signal-to-noise ratio (SNR) in a fading channel without using channel state feedback or incremental redundancy. We have defined nonuniform phase shift key (PSK) and quadrature amplitude modulation (QAM) constellations with an arbitrary number of classes of bits. These constellations may also be of interest for further research into unequal error protection. We present simulations of the throughput in Rayleigh fading and lognormal shadowing, and discuss the cases where our proposed scheme may improve the throughput compared to standard ARQ using uniform signal constellations.

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.