And-forward Research Articles

Remote Information And Power Transfer For Multi Relay-Assisted Agreeable Communication

In this paper, we studied about Simultaneous wireless information and power transfer (SWIPT) in multi relay-helped two-jump hand-off framework, where different hand-off hubs all the while help the transmission from source to goal utilizing the idea of dispersed space-time coding. Each hand-off applies control part convention to arrange the got flag vitality for data deciphering and vitality gathering. The streamlining issues of intensity part proportions at the transfers are planned for both decipher and-forward (DF) and intensify and-forward (AF) handing-off conventions. Productive calculations are proposed to discover the ideal arrangements. Recreations check the viability of the proposed plans.

Relaying Protocols for Wireless Energy Harvesting and Information Processing

Most of the ongoing exploration in wireless relay node networks and data preparing has considered point-to-point correspondence system. In remote helpful or then again sensor organizes, the hand-off or sensor relay node may have restricted battery holds and may need to depend on some outside charging component so as to stay dynamic in the system. Along these lines, vitality reaping in such systems is especially significant as it can empower data handing-off. In this thesis, we are worried about the issue of remote vitality collecting and data preparing in an intensify and-forward (AF) remote agreeable or sensor arrange. We consider the situation that a vitality obliged hand-off relay node harvests vitality from the RF sign communicated by a source node and utilizations that reaped vitality to advance the source signal to a destination node. We consider time switching (TS) and power switch (PS) scheme structures. we propose two transferring conventions: i) TS-based handing-off (TSR) convention and; ii) PS-based handing-off (PSR) convention for discrete data handling and vitality reaping at the vitality compelled wireless relay node. The primary commitments of this thesis are abridged as pursues: • We propose the TSR and the PSR conventions to empower remote vitality reaping and data handling at the vitality obliged transfer in remote AF transferring systems, in light of the TS and PS collector structures. • For the TSR and the PSR conventions, we determine logical articulations for the reachable throughput at the goal. • Comparing the TSR and the PSR conventions, our numerical investigation demonstrates that in postponement restricted transmission mode, the throughput execution of the TSR convention is better than the PSR convention at higher transmission rates, at generally lower signal-to-commotion proportion (SNR), and for lower vitality gathering productivity. • We propose the combination ATPSR system and demonstrate the optimal throughput for that system. • Finally, design and built the hardware circuit and using particle swarm optimization techniques to find the optimal value for the parameters.

Improve the Performance of Orthogonal Frequency Division Multiplexing Based Discrete Wavelet Transform Using Cooperative Communication System

Cooperative communication mean remote hubs can help each other for communication. In this work, contemplate agreeable Symmetrical Recurrence Division Multiplexing (OFDM) based Discrete wavelet change (DWT).OFDM Cooperative l plan for multi-hub remote systems utilizing both Open up and-Forward (AF) and Decipher and-Forward (DF) handing-off. In this paper, an enhance the execution OFDM-DWT. We expect that the source and the transfer are gathered. Subsequent to interpreting, the transfer rearranges the information before transmitting towards the goal. Thus, the goal gets two individual imitations of the transmit flag and utilize decent variety consolidating. The bit mistake execution is offered, for the assembled organize. BER reenactment in channels An and B demonstrates that the handing-off convention bolstered agreeable OFDM-DWT framework beats flag. Recreation results express that the recommended remapping assorted variety strategy at the hand-off accomplishes a superior execution of OFDM-DWT based arranged hand-off correspondences Keywords —OFDM, DWT, AF, DF, cooperative DOI : 10.7176/NCS/10-03 Publication date :July 31 st 2019

Amplify-and-Forward Strategy Using MRC Reception Over FSO Channels with Pointing Errors

Free-space optical (FSO) systems offer ultrahigh data rates for a number of terrestrial applications. This paper presents what we believe is the first characterization of average bit error rate (BER) for a cooperative FSO system that uses channel side information-assisted amplify- and-forward (AF) relaying when line-of-sight (LOS) is available. This paper uses maximum ratio combining reception at the destination node to maximize the output signal-to-noise ratio under pointing error effects. An asymptotic closed-form expression for the BER is obtained over gamma–gamma fading channels with pointing errors. The developed asymptotic expression is used to analyze the diversity order gain in relation to the direct path link. The maximum diversity order is determined to be βSD + min(βSR, βRD), where βSD, βSR, and βRD are atmospheric turbulence parameters corresponding to the source–destination, source-relay, and relay-destination links, respectively. Moreover, optimal relay placement, which plays an important role in the performance, is derived by taking full advantage of asymptotic expressions without the need to use optimization methods. Obtained results corroborate that a higher diversity order gain and, hence, a better BER performance, is achieved compared to the direct path link and equivalent AF dual-hop transmissions.

Outage Performance of Bidirectional Full-Duplex Amplify-and-Forward Relay Network with Transmit Antenna Selection and Maximal Ratio Combining

In this paper, a bidirectional full-duplex amplify- and-forward (AF) relay network with multiple antennas at source nodes is proposed. Assuming that the channel state information is known at the source nodes, transmit antenna selection and maximal ratio combining (MRC) are employed when source nodes transmit information to the relay node and receive information from the relay node respectively, in order to improve the overall signal-to-interference plus noise ratio (SINR). Analytical expressions are derived for tight upper bound SINR at the relay node and source nodes upon reception. Further, losed form expressions are also derived for end-to-end outage probability of the proposed bidirectional full-duplex AF relay network in the Nakagami-m fading channel environment. Although self-interference at the relay node limits the performance of the full-duplex network, the outage performance of the proposed network is better than that of conventional bidirectional full-duplex and half-duplex AF relay networks, due to the selection diversity gain in TAS and diversity and array gain in MRC.

A novel forwarding method for full-duplex two-way relay networks

An estimate-and-forward (EF) scheme for single-input single-output (SISO) and multiple-input multiple-output (MIMO) full-duplex two-way relay networks is proposed and analyzed. The relay estimates the received signal from two terminal nodes by a minimum mean squared error (MMSE) estimation and forwards a scaled version of the MMSE estimate to the destination. The proposed EF outperforms conventional amplify- and-forward (AF) and decode-and-forward (DF) across all signal-to-noise ratio (SNR) region. Because its computational complexity is high for relays with a large number of antennas (large MIMO) and/or high order constellations, an approximate EF scheme, called list EF, are thus proposed to reduce the computational complexity. The proposed list EF computes a candidate list for the MMSE estimate by using a sphere decoder, and it approaches the performance of the exact EF relay at a negligible performance loss. The proposed forwarding approach also could be used to other relay networks, such as half-duplex, one-way or massive MIMO relay networks.

Tối ưu thông lượng mạng chuyển tiếp AF hai chiều với phần cứng không lý tưởng cho truyền năng lượng vô tuyến

In this paper, we investigate the performance of energy harvesting enabled two-way relaying network (TWRN) with amplify- and- forward (AF) protocol. Particularly, this paper also determines effect of hardware impairments on the outage probability and the throughput. To evaluate harvested energy efficiency, we propose energy harvesting policies at relay node and destination node, namely time switching imperfect relay (TSIR), time switching imperfect source (TSIS). Finally, the numerical and simulation results provide practical insights into the impact of transmitted power, level of hardware impairments and energy harvesting time factors on the performance of energy enabled two-way relaying network.

Performance Comparisons of Optimal Power Allocation over Nakagami-m and Rayleigh Fading Channels in Wireless Cooperative Systems

Cooperative wireless communication has been newly proposed in wireless communication systems for discovering the inherent spatial diversity in relay channels. The Amplify- and-Forward (AF) cooperation protocols with multiple relays have not been sufficiently examined; however, it has a low complexity in terms of application. Through this article, we evaluate a cooperative diversity technique whereby a source broadcasts some data to a destination with the assistance of multiple relay nodes with AF protocols, by taking into account the challenge of allocating power to be able to increase the total capacity of AF and also enhance resource utilization. We analyse the optimality of how much the power should really be allocated at the source as well as relays system by optimizing the symbol error rate (SER) performance in a useful method on the basis of Rayleigh and Nakagami- m fading. Firstly, we derive a closed-form SER formulation for MPSK signal making use of the idea of moment generating function (MGF) and some statistical approximations in high signal to noise ratio (SNR) for the system under studied. We therefore determine a tight corresponding lower bound, which converges to the identical limit the same as the theoretical upper bound, after that develops an optimal power allocation (OPA) strategy with mean channel gains over Rayleigh and also Nakagami- m fading to reduce the SER. Simulation results prove that our approach using Nakagami- m fading outperforms the (OPA) using Raleigh fading scheme and is tight with the theoretical approximation based on the SER upper bound in high SNR for a different number of relays .  Index Terms—Wireless communication, amplify-and-forward, symbol error rate, Nakagami- m fading, power allocation.

Joint Power Allocation and Relay Selection in Energy Harvesting AF Relay Systems

In this letter, we propose joint relay selection and power allocation schemes for maximization of the throughput of an amplify—and—forward (AF) cooperative communication system where the source and the relays are energy harvesting (EH) nodes. We formulate an offline optimization problem which can be solved optimally by the generalized Bender's decomposition. For real—time implementation with low computational complexity, we propose two suboptimal online power allocation schemes. The performance of the proposed schemes is evaluated via simulations.

Cooperative network-coding system for wireless sensor networks

Describes a cooperative network coding system for wireless sensor networks. In this paper, we propose two practical power) and bandwidth)efficient systems based on amplify)and)forward (AF) and decode)and)forward (DF) schemes to address the problem of information exchange via a relay. The key idea is to channel encode each source’s message by using a high)performance non)binary turbo code based on Partial Unit Memory (PUM) codes to enhance the bit)error)rate performance, then reduce the energy consumption and increase spectrum efficiency by using network coding (NC) to combine individual nodes’ messages at the relay before forwarding to the destination. Two simple and low complexity physical layer NC schemes are proposed based on combinations of received source messages at the relay. We also present the theoretical limits and numerical analysis of the proposed schemes. Simulation results under Additive White Gaussian Noise, confirm that the proposed schemes achieve significant bandwidth savings and fewer transmissions over the benchmark systems which do not resort to NC. Theoretical limits for capacity and Signal to Noise Ratio behaviour for the proposed schemes are derived. The paper also proposes a cooperative strategy that is useful when insufficient combined messages are received at a node to recover the desired source messages, thus enabling the system to retrieve all packets with significantly fewer retransmission request messages.

Relay assisted F/TDMA ad hoc networks: node classification, power allocation and relaying strategies

This paper considers the design of relay assisted F/TDMA ad hoc networks with multiple relay nodes each of which assists the transmission of a predefined subset of source nodes to their respective destinations. Considering the sum capacity as the performance metric, we solve the problem of optimally allocating the total power of each relay node between the transmissions it is assisting. We consider four different relay transmission strategies, namely regenerative decode-and-forward (RDF), nonregenerative decode-and-forward (NDF), amplify- and-forward (AF) and compress-and-forward (CF). We first obtain the optimum power allocation policies for the relay nodes that employ a uniform relaying strategy for all nodes. We show that the optimum power allocation for the RDF and NDF cases are modified water-filling solutions. Weobserve that for a given relay transmit power, NDF always outperforms RDF whereas CF always provides higher sum capacity than AF. When CF and NDF are compared, it is observed that either of CF or NDF may outperform the other in different scenarios. This observation suggests that the sum capacity can be further improved by having each relay adopt its relaying strategy in helping different source nodes. We investigate this problem next and determine the optimum power allocation and relaying strategy for each source node that relay nodes assist. We observe that optimum power allocation for relay nodes with hybrid relaying strategies provides higher sum capacity than pure RDF, NDF, AF or CF relaying strategies.