Hybrid Decode-amplify-forward Research Articles

Outage performance prediction of cooperative vehicle network based on sparrow search algorithm based on back‐propagation neural network

AbstractWith the support of the sixth‐generation mobile networks (6G) technology, the Internet‐of‐Vehicle (IoV) can realize the perception and monitoring of vehicle road information. However, due to the change of network topology and various environment, the reliable performance of the communication link is facing challenges. For the sake of improving communication quality, a cooperative vehicular network (CVN) system is established, which adopts cooperative communication and multiple input multiple output (MIMO) technology. According to the signal‐to‐noise ratio (SNR) threshold of relay vehicles, using hybrid decode‐amplify‐forward (HDAF) protocol and combining with antenna selection, the analytical expression of outage probability (OP) with Meijer‐G function is obtained. For predicting the OP accurately, the sparrow search algorithm based on back‐propagation neural network (SSA‐BPNN) is put forward. The simulation results show that the cascade order of the channels has a negative effect on the OP. Meanwhile, the prediction accuracy of SSA‐BPNN is 64.8% higher than that of BPNN, and 98.96% greater than that of general regression neural network, and the convergence rate is faster than ICS‐BPNN.

Performance of cooperative relay protocol in 5G mobile communication network over Rayleigh fading channel

This paper presents the performance of a new cooperative relay protocol in mobile network over Raleigh environment. Characteristically, the 5G network at 28 GHz covers short distances due to its shorter wavelength. Extending network coverage area and improvement of signal quality is a necessity. In this work, high performance hybrid relay nodes were proposed to improve quality of the signal and increase the signal coverage distance. Mathematical expression was successfully derived for new hybrid decode amplify forward (HDAF) protocol. The destination node combines received symbols from hybrid relay nodes and source node using maximal ratio combiner (MRC) for optimal performance. The performance of the developed model was evaluated using bit error rate (BER), outage probability (Pout) and processing time (Ptime) at different signal to noise ratio (SNR). Comparatively the developed HDAF protocol performed better than DF and AF by having a lower BER, Pout and Ptime values. The result also shows that HDAF relay protocol has the potential to mitigate signal interference and extend the coverage area in 5G network.

Performance Analysis for Cooperative Communication System in Optical IoUT Network With HDAF Strategy

In this work, a cooperative optical Internet of Underwater Things (IoUT) system with hybrid decode-amplify-forward (HDAF) strategy is first proposed and investigated over the aggregated underwater wireless optical communication (UWOC) channel. The impacts of absorption, scattering and the misalignment caused by spatial spreading in the sea, which are modeled by the beam spread function (BSF), as well as the oceanic turbulence on the underwater optical links are all included to describe the practical channel characteristics. With the help of Gauss-Hermite and Gauss-Legendre quadrature numerical methods, the closed-form expressions of the average bit error ratio (ABER) and outage probability for this cooperative optical HDAF-IoUT system are derived and verified by the Monte Carlo (MC) simulations. Furthermore, numerical analyses are offered to explore the effects of water type, turbulence strength, relay location and power allocation scheme on this HDAF-IoUT system. The performance of this optical system over the mixture Exponential Generalized Gamma (EGG) channel is also given for comparison. The obtained results indicate that the optical HDAF-IoUT system is superior to the IoUT system with fixed amplify-and-forward (FAF) strategy, and has a better performance when the relay is close to the middle position for a fixed power allocation scheme. This work is beneficial for the cooperative system design in IoUT network.

Outage Probability Performance Analysis and Prediction for Mobile IoV Networks Based on ICS-BP Neural Network

In the field of transportation, the Internet of Vehicles (IoV) is an important component of the Internet of Things. The vehicle-to-vehicle communication is particularly challenging in mobile IoV networks because they are operated in complex and highly variable environments. The mobile IoV transmission interruption level can be evaluated by the outage probability (OP) performance. If the OP performance can be analyzed and predicted accurately, the Quality of Service (QoS) in the mobile IoV networks can be improved. However, the analysis and prediction of mobile IoV transmission channels is very challenging because they are highly dynamic. In this article, the analysis and prediction of the OP performance for mobile IoV networks are investigated. A hybrid decode-amplify-forward (HDAF) relaying scheme with transmit antenna selection (TAS) is considered. The exact OP expressions are derived in a closed form, and the analytical results are verified. To realize the real-time analysis of the OP performance, an intelligent OP prediction algorithm based on the improved cuckoo search (ICS) is presented. The proposed algorithm is compared with different methods and the results show that it has a better OP prediction performance. The prediction accuracy of ICS-BP can be increased by 51.8% compared with the existing algorithms.

RF Energy Harvesting in Hybrid Two-Way Relaying Systems With Hardware Impairments

In this paper, we investigate the performance of energy harvesting two-way relay systems in the presence of transceiver hardware impairments (HIs). In order to improve the reliability of the communication links, we employ a three-phase hybrid decode-amplify-forward (HDAF) based relaying scheme. In the considered system, the battery-enabled relay node harvests energy from the ambient radio-frequency (RF) signals using a time switching approach. We demonstrate that HIs pose detrimental impact on the performance of system by invoking ceiling effects, primarily when high target rates are anticipated. Consequently, we propose an improved HDAF (IHDAF) relaying scheme which makes the efficient use of available degrees of freedom and thereby enhances the system performance significantly. As such, the IHDAF relaying may induce slightly higher complexity due to involvement of the limited feedback mechanism. However, the benefits offered by this scheme far outweigh its limitation. For the considered system, we derive the user outage probability expressions for both the schemes by applying selection cooperation between direct and relayed links over Nakagami-m fading channels. We also analyze the system throughput and energy efficiency for the two schemes to obtain various useful insights. Finally, numerical and simulation results are provided for the validation of the derived analytical expressions.

Performance Analysis of Multi-Source Multi-Destination Cooperative Vehicular Networks With the Hybrid Decode-Amplify-Forward Cooperative Relaying Protocol

This paper provides symbol-error-rate (SER) performance analysis and minimum power allocation for multi-source multi-destination cooperative vehicular networks using the hybrid decode-amplify-forward (HDAF) cooperative relaying protocol. Previous studies of power allocation minimize the outage probability subject to a total power constraint. Our approach aims to minimize the power allocation in order to maintain the SER below a specific threshold and thus it achieves lower power consumption. Numerical tests show that HDAF has significantly reduced SER compared with the forward strategies of amplify-and-forward (AF) and decode-and-forward (DF). Furthermore, the power consumption in our proposed approach is much less than that in AF and DF.

TAS-Based Incremental Hybrid Decode–Amplify–Forward Relaying for Physical Layer Security Enhancement

In this paper, a transmit antenna selection (TAS)-based incremental hybrid decode–amplify–forward (IHDAF) scheme is proposed to enhance physical layer security in cooperative relay networks. Specifically, TAS is adopted at the source in order to reduce the feedback overhead. In the proposed TAS-based IHDAF scheme, the network transmits signals to the destination adaptive select direction transmission (DT) mode, AF mode, or DF mode depending on the capacity of the source-relay link and source-relay link. In order to fully examine the benefits of the proposed TAS-based IHDAF scheme, we first derive its secrecy outage probability (SOP) in a closed-form expression. We then conduct asymptotic analysis on the SOP, which reveals the secrecy performance floor of the proposed TAS-based IHDAF scheme when no channel state information is available at the source. Theoretical analysis and simulation results demonstrate that the proposed TAS-based IHDAF scheme outperforms the selective decode-and-forward, the incremental decode-and-forward, and the noncooperative DT schemes in terms of the SOP and effective secrecy throughout, especially when the relay is close to the destination. Furthermore, the proposed TAS-based IHDAF scheme offer a good tradeoff between complexity and performance compared with using all antennas at the source.

Performance study of hybrid decode–amplify–forward (HDAF) relaying scheme for physical layer security in wireless cooperative network

SummaryIn this paper, the secrecy performance and power allocation of the signal‐to‐noise ratio‐based hybrid decode–amplify–forward (HDAF) relaying protocol in wireless cooperative network are investigated to get security at physical layer. The performance metrics considered are secrecy rate and intercept probability. The Ergodic secrecy rate is approximated theoretically. The effect of relay and eavesdropper locations on the secrecy performance of the system is analyzed. It is found that maximum secrecy rate is obtained for the relay close‐to‐destination case and minimum for the relay close‐to‐eavesdropper case. Jamming schemes are superior in secrecy rate performance than without jamming schemes. To enhance the secrecy rate further with the optimized relay and jammer powers, invasive weed optimization (IWO) algorithm‐based power allocation is proposed. Here, maximizing the secrecy rate is defined as the cost function for the proposed IWO algorithm‐based power allocation. Comparative study is done over the conventional equal and proposed power allocation schemes for validation. The proposed power allocation scheme proved to be superior. Copyright © 2016 John Wiley & Sons, Ltd.

Outage performance improvement with cooperative relaying in cognitive radio networks

In this paper, we investigate the outage probability in three different relay modes, namely Amplify-and-Forward (AF), Decode-and-Forward (DF), and Hybrid Decode-Amplify-Forward (HDAF). We derive the closed-form outage probability expressions for cooperative communication. Our aim is to ensure the quality of service (QoS) of the primary link while minimizing the outage probability of the cognitive radio user. The cooperation based spectrum access is investigated at the secondary network. The cognitive transmitter will allocate low power if the quality of service is very rigid. Firstly, it is beneficial that the cooperation is obtained at the cognitive user from the surrounding cognitive users to decrease outage probability. Secondly, we select the best relay that can provide the minimal outage probability for cooperation. Finally, we investigate the outage probability under the peak and average interference constraints. The results indicate that the average interference constraints has lower outage probability than the peak interference constraints, due to the power adaptation between the transmitter and relay. The comparison among three cooperation relay modes shows that the HDAF outperforms the AF and DF. At the same time, we can see that the performance gain of the HDAF cooperation is better than the other modes, and a lower outage probability can be acquired as the number of potential relays increases.

Power Allocation for a Hybrid Decode–Amplify–Forward Cooperative Communication System With Two Source–Destination Pairs Under Outage Probability Constraint

We develop a two-source–destination-pair cooperative communication scheme that can achieve multiuser diversity and cooperative diversity. In this scheme, we use hybrid decode–amplify–forward (HDAF) protocol to improve system performance. From practical point of view, HDAF protocol performs better than amplify-and-forward and decode-and-forward protocols by combining the merits of both. Meanwhile, we derive a closed-form expression of outage probability associated with HDAF protocol analyzed. Based on outage probability constraint, we investigate optimal power allocation that minimizes the total power. Numerical analysis is used to confirm the accuracy of the derived theory and to examine the performance of our proposed cooperative scheme, particularly as we analyze power savings in using optimal power allocation compared with equal power allocation, which is commonly assumed in previous studies. It is shown that significant power savings can be obtained by using the proposed power optimization method.

English

To achieve the multiuser diversity and cooperative diversity, a two source destination pair is considered for cooperative communication system. Hybrid Decode Amplify Forward (HDAF) Relaying Protocol improves the system performance by combining the merits of both Amplify Forward (AF) and Decode Forward (DF) protocols is used. The fast and efficient Parallel Shift Water Filling (SPWF) algorithm can minimize the total power, based on the outage probability constraint. In the conventional algorithms, the solution is obtained by an iterative binary searching and Lagrange Multiplier searching process. In contrast, PSWF Algorithm removes the iterative searching process. It executes the PSWF only once, and then directly calculates the final solution with the parallel shift property as an enabling mechanism. Numerical analysis is used to compare the various relaying protocols based on outage probability and Bit Error Rate.

Performance Analysis of SNR-Based HDAF M2M Cooperative Networks

The lower bound on outage probability (OP) of mobile-to-mobile (M2M) cooperative networks overN-Nakagami fading channels is derived for SNR-based hybrid decode-amplify-forward (HDAF) relaying. The OP performance under different conditions is evaluated through numerical simulation to verify the accuracy of the analysis. These results show that the fading coefficient, number of cascaded components, relative geometric gain, and power-allocation are important parameters that influence this performance.

Hybrid decode-amplify-forward (HDAF) scheme in distributed Alamouti-coded cooperative network

In this article, a signal-to-noise ratio (SNR)-based hybrid decode-amplify-forward scheme in a distributed Alamouti-coded cooperative network is proposed. Considering a flat Rayleigh fading channel environment, the MATLAB simulation and analysis are carried out. In the cooperative scheme, two relays are employed, where each relay is transmitting each row Alamouti code. The selection of SNR threshold depends on the target rate information. The closed form expressions of symbol error rate (SER), the outage probability and average channel capacity with tight upper bounds are derived and compared with the simulation done in MATLAB environment. Furthermore, the impact of relay location on the SER performance is analysed. It is observed that the proposed hybrid relaying technique outperforms the individual amplify and forward and decode and forward ones in the distributed Alamouti-coded cooperative network.

Outage Performance of Hybrid Decode–Amplify–Forward Protocol with the nth Best Relay Selection

In this paper, we consider the Hybrid Decode---Amplify---Forward protocol with the $$n$$ n th best-relay selection scheme. In the best-relay selection scheme, the best relay only forwards the sourc...

Performance of hybrid decode–amplify–forward protocol for multiple relay networks over independent and non-identical flat fading channels

In this study, the authors investigate the hybrid decode-amplify-forward (HDAF) relaying protocol for the multiple parallel relays over independent and non-identical distribution flat Rayleigh fading channels using maximum ratio combining at the destination. They derive closed-form tight bounds for the outage probability and bit error rate (BER) of the HDAF relaying protocol. They also show that the outage probability performance of this protocol outperforms decode-forward (DF) protocol, and is very close to amplify-forward (AF) scheme. On the other hand, the BER of the HDAF scheme is superior to AF protocol, and is close to BER of DF scheme. From practical point of view, when taking into account outage and BER performance of a system together, the HDAF protocol performs better than AF and DF schemes by combining the merits of both. Also, the authors investigate power allocation among the relay nodes to minimise the system outage probability and BER under total and individual power constraints. Numerical results are provided to show the correctness of our analytical expressions.

On the Performance Gain of Hybrid Decode-Amplify-Forward Cooperative Communications

We investigate the performance of adaptive decode-forward (ADF), amplify-forward (AF), and hybrid decode-amplify-forward (HDAF) relaying protocol. Specifically, we derive the closed-form expression of symbol error probability (SEP) for these three relaying protocols. For the AF protocol, we derive a simpler and more tractable final result than previously published work. Furthermore, analyzing the high signal-to-noise ratio (SNR) regime, we derive an asymptotically tight approximation for SEP. The approximation is used to assess an important aspect between the three different relaying protocols, i.e., the SEP performance gain of HADF over the two conventional relaying schemes ADF and AF. It is shown that the performance gain of HDAF over ADF and AF significantly depends on the relative value of channel conditions between source-to-relay and relay-to-destination links. Interestingly, it is shown that HDAF has no benefit compare to the two others if the relay is located close to the source. In contrast, the performance gains of HDAF over the ADF and AF scheme are remarkably large as the relay moves nearby the destination. Specifically, the numerical results given as well as our analysis indicate that for QPSK modulation, HDAF outperforms ADF and AF with a performance improvement by 5 dB and 6 dB, respectively.

Efficient Message Relaying for Wireless User Cooperation: Decode-Amplify-Forward (DAF) and Hybrid DAF and Coded-Cooperation

Amplify-forward (AF) can be modeled as a way of forwarding soft reliability information extracted directly from the transmit channel, without utilizing the channel code that may well exist in the source-packet. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Decode-forward </i> exploits the channel code but forwards the hard-decisions only. These observations motivate the proposition of an efficient new relaying strategy, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">decode-amplify-forward</i> (DAF). By having the relay perform soft decoding and forward the reliability information at the output of its decoder instead of that from the raw channel, DAF cleverly combines the merits of both AF and DF: soft information representation in AF and coding gain in DF. A hybrid scheme of DAF and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">coded cooperation </i> (DAF-CC), implemented through simple time-sharing, is further discussed. The information-theoretic achievable rates of these schemes are formulated for channels with binary inputs and Gaussian outputs. Both analysis and simulations confirm that the proposed schemes are capable of considerably better performances than the existing schemes.