Dual-hop Amplify-and-forward Relay Research Articles

Analysis of SWIPT based dual-hop AF relay with SSK modulation over Nakagami-m fading channel

Space shift keying (SSK) modulation performance is analyzed with simultaneous wireless information and power transfer (SWIPT) based cooperative amplify-and-forward (AF) relaying system over the Nakagami-m fading channel. SWIPT technique can remove the need for power supply at the relays in cooperative communication. In contrast, SSK is a low complex index modulation technique that eliminates inter antenna synchronization, inter-channel interference and reduces the number of radiofrequency chains. Closed-form expression for average bit error probability (ABEP) is derived using a single AF relay with selection combining (SC) at the receiver, and an Upper bound ABEP expression is derived for multiple AF relays with the direct link (DL) from source to destination. The partial relay selection (PRS) technique has been proposed with energy harvesting (EH) to reduce the hardware complexity compared to the multiple relays. Numerical and computer simulation results are presented with the discussion. The result demonstrates that EH with SSK modulation can improve the system performance.

Higher order statistics of cooperative mobile-to-mobile relay communications over composite fading channels

The paper investigates mobile-to-mobile (M2M) dual-hop amplify-and-forward relay (AFR) communications in composite fading environments. We model composite fading signal as the product of Nakagami-m (Nm) and Gamma (G) random processes (RPs) in order to address multipath-shadowing scenario and derive novel, fast computing, closed form mathematical formulas for: 1) probability density function; 2) cumulative distribution function; 3) outage probability; 4) average level crossing rate; 5) average fade duration. The integral form statistical expressions are directly approximated by Laplace approximation (LA) method and exponential LA method. Moreover, we extended the model to cooperative M2M relay communications with n parallel independent dual-hop AFR links with selection combining scheme (SCS) at reception. The obtained results are numerically presented in order to show the impact of multipath-shadowing severity sets of parameters on the proposed M2M system. The detailed comparison of exact and approximated numerical results is provided for all considered statistical measures.

Performance Analysis and Beamforming Designs of MIMO AF Relaying With Hardware Impairments

This paper investigates outage performance analysis and beamforming designs of a dual-hop multiple-input multiple-output (MIMO) amplify-and-forward (AF) relay channel with hardware impairments. We derive analytical closed-form expressions of the exact outage probability with fixed-gain and variable-gain relaying beamforming schemes. Moreover, asymptotic outage probability expressions are analyzed at high signal-to-noise ratio (SNR), which show that how hardware impairments and the number of relay antennas affect the system performance. We find that the outage probability in both relaying beamforming schemes has lower bounds with the increase of the SNR. Especially in the fixed-gain relaying beamforming scheme, we obtain a simple floor of the outage probability that is a monotone increasing function of hardware impairments’ level. To further compensate the performance loss brought by hardware impairments, we optimize the beamforming matrix for the dual-hop MIMO AF relay network by maximizing the end-to-end signal-to-noise-and-distortion ratio with the relay's power constraint. We derive optimal beamforming designs for sum-power constraint and for per-antenna power constraints. Our results show that the performance of the variable-gain relaying is superior to the fixed-gain relaying, especially for the case with varying scaling factor of the relay beamforming matrix. It is also shown that more performance gains can be attained with the proposed optimal beamforming designs.

Performance Analysis of Dual-Hop MIMO AF Relaying Network With Multiple Interferences

In this paper, we investigate the performance of a dual-hop multiple-input–multiple-output (MIMO) amplify-and-forward (AF) relay network, where the source, relay, and destination are all equipped with multiple antennas. By using maximum ratio transmission (MRT) at the transmitter and maximum ratio combining (MRC) at the receiver, we first obtain the output signal-to-interference-plus-noise ratio (SINR) of the dual-hop AF relay system, considering multiple cochannel interferences (CCIs), as well as noise at the relay. Then, we derive an exact closed-form expression for the outage probability (OP), and the asymptotic result of OP at high SNR, which can be used to calculate the array gain and diversity order. Finally, computer simulations are conducted to validate the performance analysis. Our new analytical expressions not only provide a fast and efficient method to evaluate the system performance but enable us to gain valuable insights into the effects of key parameters on the MIMO AF relaying network performance that benefits from implementing multiple antennas at each of the three nodes as well.

Performance Analysis of Dual-Hop AF Relay Networks in the Presence of Channel Estimation Errors and Feedback Delay

In this letter, we investigate the performance of multiple-input multiple-output two hop beamforming amplify-and-forward (AF) relay networks under imperfect channel state information (CSI) including channel estimation errors (CEE) and feedback delay (FD). To quantify the effect of imperfect CSI on our considered network, we derive the closed-form expression for the outage probability. To gain more insight, we also present an asymptotic analysis which provides the details of the diversity order and array gain. Through our works, one can see the effect of CEE and FD on the system as well as the benefits of deploying multiple antennas at the terminals. Numerical and simulation results are provided to verify the analysis and compare the performance of the considered network for two different models for channel estimation error.

Secrecy rate analysis of dual-hop AF relay wiretap channel

An amplify-and-forward(AF) dual-hop relay is proposed for secure communication within Wyner s wiretap channel.Based on an information-theoretic formulation,the average secrecy rate is characterized when two legitimate partners communicate over a quasi-static fading channel.Theoretical analysis and simulation results show that both cooperative strategies of average power scaling(APS) and instantaneous power scaling(IPS) are proved to be able to achieve information-theoretic security,and eavesdropper is unable to decode any information.

Outage Performance of Dual-Hop AF Relay Channels with Co-Channel Interferences over Rayleigh Fading

This paper studies the outage performance of a dual-hop amplify-and-forward (AF) relay fading channel in an interference-limited environment. The relay and destination nodes are corrupted by multiple co-channel Rayleigh interferences. New exact closed-form expressions for the outage probability for channel-state-information (CSI)--assisted relay, in which gain is dependent on previous hop CSI and interference, are derived. Monte Carlo simulations are performed to verify the obtained theoretical results. For the cases where the number of interferers at the relay and the destination node is equal, we derive novel expressions for outage probability upper and lower bounds.

Performance analysis of dual-hop relay systems with single relay selection in composite fading channels

Abstract In this paper, we present novel and easy-to-evaluate expressions for the performance of dual-hop relaying with best relay selection operating over generalized- K fading channels. Since it is hard to find a closed-form expression for the probability density function (PDF) of the exact end-to-end signal-to-noise ratio (SNR) at the destination node even for the single dual-hop system with amplify-and-forward (AF) relaying, we use a tight upper bound value instead. Using the approximate value for the end-to-end SNR, closed-form expressions for the statistics of the SNR, the average bit and symbol error probabilities, and the ergodic capacity for the single dual-hop AF relay system, are derived. Moreover, assuming independent nonidentical fading conditions across multiple dual-hop relay links, we derive lower performance bounds for the single relay selection scheme with AF relaying. The final expressions are useful in the performance evaluation of AF opportunistic relaying in a generalized composite radio environment. Simulation results are also given to verify the analytical results.