Automatic Repeat Request Protocol Research Articles

Closed-Form Error Analysis of AF-CARQ with CSI-Assisted Relay over Nakagami- $$m$$ m Fading Channels

This paper presents a new Amplify-and-Forward Cooperative Automatic Repeat reQuest protocol with channel state information-assisted relay which is more suitable for the only-read access networks. The channels of any pair of terminations are quasi static flat Nakagami- $$m$$ m fading channels, which are mutually independent and non-identically distributed. Assuming that the coherent equal gain combining is adopted to combine the retransmitted signals from the same link at the destination and selective combining is adopted to the signals from different links. Based on the approximation of product of Nakagami- $$m$$ m variables, we obtain the end-to-end signal-to-noise rate of any link. The closed-form expression of the average bit error rate for several modulation schemes is obtained by analyzing cumulative distribution function (CDF) and Gaussian Q-function. Then we analyze the amount of fading of the fading channels by the $$n$$ n order moment which is obtained by CDF. Numerical simulation results show that the relay node can resist the fading of system effectively comparing with the system without relay node. And with the increasing of the number of transmission, the performance advantage of relay link is more and more obviously. It is better to let the maximum transmission time $$F=6$$ F = 6 , which is very useful for improving the transmission efficiency of the truncated ARQ system. The maximum reduction of amount of fading can be reached when $$t=3$$ t = 3 , if the total number of transmission is $$f=6$$ f = 6 . The number of bits in the frame should not have too big.

On Noisy ARQ in Block-Fading Channels

Assuming noisy feedback channels, this paper investigates the data transmission efficiency and robustness of different automatic repeat request (ARQ) schemes using adaptive power allocation. Considering different block-fading channel assumptions, the long-term throughput, the delay-limited throughput, the outage probability and the feedback load of different ARQ protocols are studied. A closed-form expression for the power-limited throughput optimization problem is obtained which is valid for different ARQ protocols and feedback channel conditions. Furthermore, the paper presents numerical investigations on the robustness of different ARQ protocols to feedback errors. It is shown that many analytical assertions about the ARQ protocols are valid both when the channel remains fixed during all retransmission rounds and when it changes in each round (in)dependently. As demonstrated, optimal power allocation is crucial for the performance of noisy ARQ schemes when the goal is to minimize the outage probability.

Cooperative ARQ With Relay Selection: An Analytical Framework Using Semi-Markov Processes

An important building block in cooperative diversity is relay selection, which has to ensure that a well-suited node is employed as a relay. The required coordination among nodes causes signaling overhead, which in turn can significantly devalue the performance benefits gained by cooperative diversity. A relay update policy defines when a new relay is selected; it can balance the tradeoff between performance and overhead. This tradeoff is studied using mathematical methods. We consider three relay selection schemes, i.e., permanent, reactive, and adaptive, which have different relay update rules. We develop an analytical framework using semi-Markov processes to evaluate the throughput and energy efficiency of cooperative automatic repeat request (ARQ) protocols in time-correlated multipath fading channels. Results reveal potential performance gains of different selection schemes under various conditions. The reactive and adaptive schemes make use of better suited relays due to frequent selections. If their selection overhead, however, is significant, a permanent relay can achieve higher throughput due to negligible overhead. The impact of temporal correlation of fading channels on throughput and energy efficiency is also shown. These insights can be applied for development of cooperative communication protocols.

New throughput-based antenna selection scheme

In this paper, a new throughput-based transmit antenna selection (AS) scheme is evaluated. First, a closed- form solution for the throughput rate of a multiple-input multiple-output (MIMO) system, with a truncated selective repeat automatic repeat request (TSR-ARQ) or selective repeat plus go-back-N automatic repeat request (SR+GBN- ARQ) protocol at the data link layer, is proposed. In addition, a throughput-based AS technique with adaptive modulation is also investigated. For this purpose, the throughput and packet error rates of a MIMO system with a transmit AS and TSR-ARQ protocol at the data link layer are analyzed. This study is conducted in 2 dierent cases. In the single-transmit AS case, the probability density functions (PDFs) of the throughput and packet error rates at the data link layer are derived. Moreover, in the case with multiple-transmit AS, a lower bound for the throughput rate and an upper bound for the packet error rate at the data link layer are determined. Consequently, the PDFs of these lower and upper bounds are extracted.

Queuing analysis of cooperative GBN-ARQ in wireless networks with peers contending for a common helper

This paper presents a new queuing model for performance analysis of go-back-N automatic repeat request (GBN-ARQ) protocol in cooperative wireless networks. In the model, cooperative medium access control (CoopMAC) protocol and dynamic radio link adaptation are taken into consideration. We analyze the probability distribution of the total delay witnessed by packets at the source side. Multi-rate transmissions are considered for all links with link adaptation. An enhanced Markov model is introduced in our model, which encompasses the following aspects: CoopMAC protocol at the MAC sub-layer; GBN-ARQ protocol at the logical link control sub-layer and the transmission using decode-and-forward cooperative diversity at the physical layer. The stochastic process of random feedback delay because of peers contending for a common helper is analyzed. The queuing system is modeled as a GI/M/1 Markov chain to acquire statistics of the exact queue length and the total delay. We analyze the effects of Doppler frequency shift and packet arrival rate on the total delay. The analysis is validated by simulation.

Analysis of Optimal Spectral Efficiency with Adaptive Modulation Coding and Cooperative ARQ Protocols

In this paper aiming at maximizing the spectral efficiency, a cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer and truncated automatic repeat request (ARQ) protocol at the data link layer in cooperation system is proposed. In order to analyze the system performance, we first derive a closed form expression of probability density function (PDF) of the received signal-to-noise (SNR) using maximum ratio combing (MRC) at the destination node, the theoretical results and simulation show that the new design outperforms the traditional AMC system especially at low SNR.

Performance Analysis of SR-ARQ Based on Geom/G/1/� Queue over Wireless Link

Selective-Repeat ARQ (Automatic Repeat reQuest) protocol is the most efficient error control technology in wireless because it allows the transmitter to retransmit only negatively acknowledges (NACK) packets. In this paper, by analyzing the transmission mechanism of SR-ARQ, the discrete-time Geom/G/1/ queue model is established sententiously based on equivalent delay under the condition that the numbers of packets entering the transmitter are assumed to be independent and identically distributed random variables. With the method of embedded Markov chain, the expression formulations of the packet mean waiting delay, system mean delay and channel utilization are explicitly obtained. And then, the sliding window length control model is built adaptively according to the change of transmission conditions. Furthermore, the influences of packet length, the successful transmission probability and packet arrival rate on system mean delay are analyzed by numerical simulation. The numerical simulation results show that the expression formulations are valid for SR-ARQ protocol.

Channel-aware MAC performance of AMC-ARQ-based wireless systems

This paper proposes a novel framework for the cross-layer design and optimization of wireless networks combining adaptive modulation and coding (AMC) at the physical (PHY) layer with automatic repeat request and channel-aware multiuser scheduling protocols at the data link control (DLC) layer. The proposed framework is based on the use of first-order two-dimensional discrete time Markov chains (DTMCs) jointly modeling the AMC scheme and the amplitude and rate of change of the wireless channel fading envelope. The behavior of the scheduler is embedded into the multidimensional PHY layer Markov model through the use of a service-vacation process. Using this PHY-media access control (MAC) Markov model, the quality of service performance at the DLC layer is discussed considering two different approaches. The first one relies on an analytical framework that is based on the multidimensional DTMC jointly describing the statistical behavior of the arrival process, the queuing system, and the PHY layer. The second one is rooted in the use of the effective bandwidth theory to model the packet arrival process and the effective capacity theory to model the PHY/MAC behavior. Both the DTMC-based and effective bandwidth/capacity-based approaches are analyzed and compared in a cross-layer design aiming at maximizing the average throughput of the system where constraints on the maximum tolerable average packet loss and delay are to be fulfilled.

On the Energy Delay Tradeoff of HARQ-IR in Wireless Multiuser Systems

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 (HARQ-IR) 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 threshold-based 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.

Secure Wireless Multicast for Delay-Sensitive Data via Network Coding

Wireless multicast for delay-sensitive data is challenging because of the heterogeneity effect where each receiver may experience different packet losses. Fortunately, network coding, a new advanced routing protocol, offers significant advantages over the traditional Automatic Repeat reQuest (ARQ) protocols in that it mitigates the need for retransmission and has the potential to approach the min-cut capacity. Network-coded multicast would be, however, vulnerable to false packet injection attacks, in which the adversary injects bogus packets to prevent receivers from correctly decoding the original data. Without a right defense in place, even a single bogus packet can completely change the decoding outcome. Existing solutions either incur high computation cost or cannot withstand high packet loss. In this paper, we propose a novel scheme to defend against false packet injection attacks on network-coded multicast for delay-sensitive data. Specifically, we propose an efficient authentication mechanism based on null space properties of coded packets, aiming to enable receivers to detect any bogus packets with high probability. We further design an adaptive scheduling algorithm based on the Markov Decision Processes (MDP) to maximize the number of authenticated packets received within a given time constraint. Both analytical and simulation results have been provided to demonstrate the efficacy and efficiency of our proposed scheme.

ARQ-Based Symmetric-Key Generation Over Correlated Erasure Channels

This paper focuses on the problem of sharing secret keys using Automatic Repeat reQuest (ARQ) protocol. We consider cases where forward and feedback channels are erasure channels for a legitimate receiver (Bob) and an eavesdropper (Eve). In prior works, the wiretap channel is modeled as statistically independent packet erasure channels for Bob and Eve. In this paper, we go beyond the state-of-the-art by addressing correlated erasure events across the wiretap channel. The created randomness is shared between two legitimate parties through ARQ transmissions that is mapped into a destination set using a first-order digital filter with feedback. Then, we characterize Eve's information loss about this shared destination set, due to inevitable transmission errors. This set is then transformed into a highly secure key using privacy amplification in order to intensify and exploit Eve's lack of knowledge. We adopt two criteria for analysis and design of the system: secrecy outage probability as a measure of the secrecy quality, and secret key rate as a metric for efficiency. The resulting secrecy improvement is presented as a function of the correlation coefficients and the erasure probabilities for both channels. It is shown that secrecy improvement is achievable even when Eve has a better channel than legitimate receivers, and her channel conditions are unknown to legitimate users.

On RANC ARQ for Wireless Relay Networks: From the Transmission Perspective

The relay-assisted, network-coding (RANC) automatic repeat request (ARQ) protocols are ARQ protocols that leverage both opportunistic retransmission and network coding for wireless relay networks. This paper proposes two single-relay RANC ARQ protocols, the listen-and-supersede (LS) protocol and the hold-and-proceed (HP) protocol. LS offers a fundamental limit to any single-relay RANC ARQ protocol. HP is a simple yet efficient RANC ARQ protocol with near-zero overhead. Moreover, we analyze saturation throughput and segment delay for both LS and HP. Their performances are compared with a representative cooperative ARQ protocol, the opportunistically forwarding (OF) protocol. Through extensive analysis and simulation results, we show that HP has a performance close to LS and outperforms OF significantly.

Delay‐limited throughput analysis of cooperative hybrid automatic repeat request in asymmetric fading channels

This study analyses the delay-limited throughput performance of an uplink cellular relay network utilising hybrid automatic repeat request (HARQ) protocol in which one mobile station (MS) communicates with one base station (BS) with the aid of one amplify-and-forward relay station (RS). The authors’ analysis allows for a practical fading scenario where MS → RS and RS → BS channels undergo independent Rayleigh and Rician fading, respectively. Delay-limited throughput expressions for two HARQ protocols are derived, respectively, namely Repetition Time Diversity and Incremental Redundancy. Furthermore, the impact of different parameters on the achievable throughput, such as the maximum HARQ round number L, line-of-sight signal K, information rate R etc., is analysed. The authors’ analysis unveils that, for the presumed dual-hop cooperation model with the specified tolerable delay requirement and given channel condition, there exists an optimal information rate R* that achieves the maximum delay-limited throughput for the two HARQ protocols. Moreover, it is disclosed that, both HARQ protocols with the adaptive optimised information rate outperform the counterpart with the fixed information rate in low and moderate SNR regions, suggesting that an adaptive transmission scheme should be employed to achieve a better throughput performance.

Energy-Delay Tradeoff Comparison of Transmission Schemes with Limited CSI Feedback

Due to increasing energy cost and various environmental issues, energy efficiency becomes an important issue in wireless communications where spectral efficiency has been considered as a key performance measure. If transmission schemes can be flexible to allow varying average transmission delay (or throughput), the energy-delay tradeoff (EDT) can be exploited. In general, the longer (average) transmission delay, the better energy efficiency can be achieved. In this paper, we study various transmission schemes with limited channel state information (CSI) feedback that can have flexible transmission delay in wireless communications, including hybrid automatic repeat request (HARQ) protocols, and derive EDT characteristics over fading channels. An opportunistic transmission scheme that relies on prior CSI feedback is studied for comparisons with HARQ protocols in terms of EDT. In order to improve the energy efficiency of HARQ, a modified transmission scheme that employs prior CSI feedback is proposed and analyzed to understand its EDT characteristics.

Novel Design and Analysis of Aggregated ARQ Protocols for IEEE 802.11n Networks

The design of wireless local area networks (WLANs) with enhanced throughput performance have attracted significant amounts of attention in recent years. Based on the IEEE 802.11n standard, frame aggregation is considered one of the major factors to improve the system performance of WLANs from the medium access control (MAC) perspective. In order to fulfill the requirements of high throughput performance, feasible design of automatic repeat request (ARQ) mechanisms becomes important for providing reliable data transmission. In this paper, two MAC-defined ARQ protocols are proposed to consider the effect from frame aggregation for the enhancement of network throughput. An aggregated selective repeat ARQ (ASR-ARQ) scheme is proposed which incorporates the selective repeat ARQ scheme with the consideration of frame aggregation. On the other hand, for worse channel quality, the aggregated hybrid ARQ (AH-ARQ) mechanism is proposed to further enhance the throughput performance by adopting the Reed-Solomon (RS) block code as forward error correction (FEC) scheme. Novel analytical models for both the ASR-ARQ and AH-ARQ protocols are established with the consideration of interfering wireless stations. Simulations are conducted to validate and compare the proposed ARQ mechanisms based on the service time distribution and system throughput. Numerical evaluations show that the proposed AH-ARQ protocol can outperform the other schemes under worse channel condition; while the ASR-ARQ scheme is superior to the other mechanisms under better channel condition.

On the Energy Efficiency of a Relaying Protocol with HARQ-IR and Distributed Cooperative Beamforming

Hybrid automatic repeat request (HARQ) protocols can be employed for reliable transmissions of delay tolerant traffics over fading channels. Relay-aided transmissions can offer various advantages over direct transmissions in wireless communications including transmission power saving. In this paper, we consider the energy efficiency of a relaying protocol that is based on the HARQ protocol with incremental redundancy (HARQ-IR) when distributed cooperative beamforming (DCB) is employed in a wireless relay system. It is assumed that multiple relays between a source node (SN) and a destination node (DN) are available for relaying and some of them are selected for DCB. In the proposed relaying protocol, the signal transmission consists of two phases and each phase can have an independent HARQ-IR protocol. It is shown in this paper that although the performance can be improved when the number of selected relays for DCB increases as the diversity gain increases, it is not true in terms of the energy efficiency. For Rayleigh fading channels, closed-form expressions are derived for the average numbers of transmissions for each phase. From them, under a certain energy efficiency criterion, we can find the optimal number of multiple selected relays for DCB to forward signals from relays to DN.

Energy-Delay Tradeoff for Wireless Relay Systems Using HARQ with Incremental Redundancy

Using relays, wireless relay systems can provide reliable transmissions when the distance between a source node (SN) and a destination node (DN) is sufficiently long and the transmission power is limited. In this paper, we study the application of the hybrid automatic repeat request (HARQ) protocol with incremental redundancy (HARQ-IR) to wireless relay systems for energy efficient reliable packet transmissions when a delay constraint is not stringent. The energy-delay tradeoff (EDT) is discussed for one-way and two-way relay systems. It is shown that direct transmissions without a relay node (RN) can be more energy efficient under a short delay constraint (or in the high power regime). On the other hand, in the low power regime (or under a long delay constraint), we can show that decoding at an RN plays a crucial role in improving energy efficiency. In particular, if decoding is performed at an RN in both one-way and two-way relay systems, relay-aided transmissions become more energy efficient than direct transmissions by a factor of greater than or equal to 8 (with a path loss exponent of 3 over Rayleigh fading channels) as the transmission power approaches 0.

A Physical Layer Secured Key Distribution Technique for IEEE 802.11g Wireless Networks

Key distribution and renewing in wireless local area networks is a crucial issue to guarantee that unauthorized users are prevented from accessing the network. In this paper, we propose a technique for allowing an automatic bootstrap and periodic renewing of the network key by exploiting physical layer security principles, that is, the inherent differences among transmission channels. The proposed technique is based on scrambling of groups of consecutive packets and does not need the use of an initial authentication nor automatic repeat request protocols. We present a modification of the scrambling circuits included in the IEEE 802.11g standard which allows for a suitable error propagation at the unauthorized receiver, thus achieving physical layer security.

On ARQ-Based Fast-Fading Channels

Automatic repeat request (ARQ) protocols are normally studied under slow-fading or quasi-static channel assumption where the fading coefficients are assumed to remain fixed during the transmission of a codeword or for the duration of all ARQ retransmission rounds, respectively. This letter investigates the performance of basic ARQ and incremental redundancy hybrid ARQ protocols in fast-fading channels where a number of channel realizations are experienced in each retransmission round. Long-term throughput, delay-limited throughput and outage probability of the ARQ schemes are obtained. Compared to slow-fading and quasi-static channels, a fast-fading channel results in a higher performance for both basic and incremental redundancy ARQ. The fast-fading channel, however, can be mapped to an equivalent slow-fading model at low signal-to-noise ratios. Finally, we show that the efficiency of ARQ protocols is overestimated if the fast-fading variations during a codeword transmission are approximated by their average value.

Cross-Layer Combining of Adaptive Modulation and Truncated ARQ Under Cognitive Radio Resource Requirements

In addressing the issue of taking full advantage of the shared spectrum under imposed limitations in a cognitive radio (CR) network, we exploit a cross-layer design for the communications of secondary users (SUs), which combines adaptive modulation and coding (AMC) at the physical layer with truncated automatic repeat request (ARQ) protocol at the data link layer. To achieve high spectral efficiency (SE) while maintaining a target packet loss probability (PLP), switching among different transmission modes is performed to match the time-varying propagation conditions pertaining to the secondary link. Herein, by minimizing the SU's packet error rate (PER) with each transmission mode subject to the spectrum-sharing constraints, we obtain the optimal power allocation at the secondary transmitter (ST) and then derive the probability density function (pdf) of the received SNR at the secondary receiver (SR). Based on these statistics, the SU's packet loss rate and average SE are obtained in closed form, considering transmissions over block-fading channels with different distributions. Our results quantify the relation between the performance of a secondary link exploiting the cross-layer-designed adaptive transmission and the interference inflicted on the primary user (PU) in CR networks.