Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Cooperative relay system.
Artykuły w czasopismach na temat „Cooperative relay system”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „Cooperative relay system”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Jiang, Bin, Yue Tang, Jianrong Bao, Chao Liu i Yanhai Shang. "Efficient Polar Coded Selective Decode-and-Forward with Cooperative Decision Threshold in Cooperative Multi-Relay Transmissions". Sensors 23, nr 1 (24.12.2022): 165. http://dx.doi.org/10.3390/s23010165.
Pełny tekst źródłaStreszczenie:
In some satellite Internet of Things (IoT) devices with terrain shielding, the qualities of the direct source-destination (S-D) channel are poor, requiring cooperative communications with multi-relays to be employed. In order to solve error propagation of current decode-and-forward (DF) on such occasions, an efficient polar coded selective decode-and-forward (SDF) cooperation method is proposed with a new decision threshold derived from channel state information (CSI). First, the proposed threshold is derived from the CSI by exploiting the channel gain ratio of optimal relay-destination link (R-D) with source-relay (S-R) link. The above R-D link possesses good channel quality among all links in the system. Second, when the channel gain ratio of certain relay links is larger than the aforementioned decision threshold, the source and all these relays cooperatively send messages together to the destination to accomplish perfect SDF transmission. Otherwise, all relays are frozen and the messages are directly transmitted through the S-D link. If it fails anyway, a retransmission is subsequently tried in the next transmission cycle. In addition, a polar code for fading channels is designed and adaptively adjusted to a proper code rate according to channel quality to attain good bit error rate (BER) performance. Simulation results show that the proposed scheme achieves about 0.9 and 0.5 dB gain at BER of 10−4, respectively, in multi-relay cooperative communications with multi-path fading channels compared with those of non-cooperation and existing polar coded cooperation channels. Therefore, the proposed polar coded SDF (PCSDF) scheme can improve both the BER and the outage probability (OP) performance in multi-relay cooperative systems, making it quite suitable for heterogeneous network applications in cooperative satellite IoT systems involving sixth-generation (6G) communications.
2
Alawady, Ahmed Allawy, Ahmed Alkhayyat, Mohammed Ahmed Jubair, Mustafa Hamid Hassan i Salama A. Mostafa. "Analyzing bit error rate of relay sensors selection in wireless cooperative communication systems". Bulletin of Electrical Engineering and Informatics 10, nr 1 (1.02.2021): 216–23. http://dx.doi.org/10.11591/eei.v10i1.2492.
Pełny tekst źródłaStreszczenie:
Cooperative communication systems, which make use of the intermediate relays between the transmitter and the receiver, have been employed as an effective technique to combat the channel fading and to enhance system performance. Cooperative systems have some drawbacks such as high latency and may diversity order not guaranteed. To alleviate the negative effects of these factors, the relay selection protocol is employed in cooperative communication systems to increase overall cooperative system performance. Relay selection in the cooperative systems enables the source to cooperate with the single relay node rather than multiple relay nodes which guaranteed the diversity order.
3
Nasaruddin, Nasaruddin, Rony Kurnia i Ramzi Adriman. "Efisiensi Daya Protokol Quantize and Forward Pada Sistem Komunikasi Kooperatif Multi-relay". Jurnal Rekayasa Elektrika 13, nr 1 (27.04.2017): 57. http://dx.doi.org/10.17529/jre.v13i1.6568.
Pełny tekst źródłaStreszczenie:
One of effective diversity techniques to combat fading on wireless channel is a cooperative communication system in which a source sends information through several relays and then forward it to a destination. A cooperative communication system has shown increased the system performance and reduced the energy consumption. However, it depends on the used relay mechanism that is relay protocols such as quantize and forward (QF) and amplify and forward (AF). In the previous research, energy efficiency of AF relay has investigated for a single-relay cooperative system, but multi-relay is more practical. Therefore, this research focuses on power efficiency in multi-relay cooperative communication system using QF protocol. The research method used is mathematical analysis and computer simulation for outage probability and power efficiency in the multi-relay QF. Simulation result found that multi-relay QF system could provide a high power efficiency, but the efficiency is reduced when the distance ratio increases. Power efficiency can be increased by adding the number of relays in the system. A comparison of power efficiency for QF and AF protocols has simulated, in which power efficiency of multi-relay QF is higher than that of multi-relay AF at distance ratio and power transmit. Thus, multi-relay QF system can provide high performance and power efficiency in the cooperative communication system.
4
Nasaruddin, Nasaruddin, Elizar Mustafa i Yusnidar Yusnidar. "Performance Evaluation of Amplify-Quantize and Forward Protocol for Multi-relay Cooperative Networks". ECTI Transactions on Electrical Engineering, Electronics, and Communications 15, nr 1 (22.08.2016): 8–18. http://dx.doi.org/10.37936/ecti-eec.2017151.171272.
Pełny tekst źródłaStreszczenie:
Fading which occurs during the process of information transmission can significantly degrade system performance. The cooperative communication system is a well-known diversity technique that is able to mitigate the impact of fading. The relay protocol is the core of such systems. In this research, we evaluated the performance of amplify-quantize and forward (AQF) relays using a hybrid of two protocols: amplify-and-forward (AF) and quantize-and-forward (QF). The outage probability and throughput of multi-relay cooperative networks were derived, and computer simulation was used to evaluate the impact of a number of parameters on the performance of the AQF relay for multi-relay cooperative networks. We also compared the outage probability and throughput of AF, QF, and direct link networks. The outage probability of AQF decreased as the number of relays increased, whereas the throughput increased. We demonstrated that amplification values and quantization levels have a significant impact on the performance of AQF multi-relay networks. Overall, AQF performed better in terms of outage probability and throughput than AF and QF, for multi-relay cooperative networks.
5
Ren, Jin. "A Switch On/Off Relaying Scheme in TDMB Cooperative System". Applied Mechanics and Materials 462-463 (listopad 2013): 167–70. http://dx.doi.org/10.4028/www.scientific.net/amm.462-463.167.
Pełny tekst źródłaStreszczenie:
Terrestrial Digital Multimedia Broadcasting (TDMB) is one popular broadcasting standard that enable digital television transmissions to hand held receivers and cooperative system take advantage of the broadcast nature of wireless channels, uses relay stations as virtual antennas. Relay stations are an attractive solution to penetrate the wireless system with lower transmitting power at the Base station. In this paper, we presented a scheme can switch on/off the power weighting ratio between Base station and Relay station in TDMB cooperative system. It will control the active relays in different channel propagations effectively.
6
D., Damodaram. "MIMO Based Cooperative Communication and Joint Maximum-Likelihood Detection for Cognitive Radio System". International Journal of Recent Technology and Engineering 10, nr 1 (30.05.2021): 39–43. http://dx.doi.org/10.35940/ijrte.a5720.0510121.
Pełny tekst źródłaStreszczenie:
In this work, novel cooperative communication strategies like Decode and Forward based relay schemes, joint maximum likelihood signal detection in combinational Multiple Input Multiple Output (MIMO) cooperative relay cognitive networks are used. The joint cooperative signal detection using Maximum-Likelihood (ML) detector at each relays, and associated path links improves the quality of services at the destination node, which can be dynamically altered using different relay combinations and associated iterative computational complexity accumulated during ML detection. Here the relay performs ML decoding and transmit the detected symbols to the destination and also to the multiple antennas equipped for cooperative communication. The same ML detection at the destination combines the MIMO based diversity to narrow down the error probability among different orthogonal transmissions. The combination of iterative signal detection and relay assisted decoding scheme shows superior error rate performance when compared to non-iterative hard decoded signal detection. The simulations results proved the influence of MIMO assisted cooperative communication and the associated performance penalty gaps that come with imperfect channel state information at the destination node.
7
Hassan, Jamal A., i Samah A. Mustafa. "Capacity of Cooperative Spatial Modulation (CSM) System with Optimum Relay Selection". Wireless Communications and Mobile Computing 2020 (24.07.2020): 1–10. http://dx.doi.org/10.1155/2020/8345878.
Pełny tekst źródłaStreszczenie:
In this work, the capacity of the cooperative spatial modulation (CSM) system is analysed. Relay-aided transmission is considered to improve the coverage and the reliability using decode and forward scheme. Due to the nonclosed form of the spatial modulation capacity function, its upper and lower bounds are derived. The lower bound of the capacity is exploited to formulate the optimal relay selection problem to maximize the channel utilization, where the optimal relay selection algorithm (ORSA) and modified maximum harmonic mean (MMHM) are proposed to select single or multiple relays. A comparison study in terms of the performance and the computational complexity is presented for the evaluation purpose. Simulation results demonstrate that the proposed algorithm significantly improves the capacity of CSM compared to other most popular relay selection strategies.
8
Bao, Jianrong, Jiawen Wu, Chao Liu, Bin Jiang i Xianghong Tang. "Optimized Power Allocation and Relay Location Selection in Cooperative Relay Networks". Wireless Communications and Mobile Computing 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/9727360.
Pełny tekst źródłaStreszczenie:
An incremental selection hybrid decode-amplify forward (ISHDAF) scheme for the two-hop single relay systems and a relay selection strategy based on the hybrid decode-amplify-and-forward (HDAF) scheme for the multirelay systems are proposed along with an optimized power allocation for the Internet of Thing (IoT). Given total power as the constraint and outage probability as an objective function, the proposed scheme possesses good power efficiency better than the equal power allocation. By the ISHDAF scheme and HDAF relay selection strategy, an optimized power allocation for both the source and relay nodes is obtained, as well as an effective reduction of outage probability. In addition, the optimal relay location for maximizing the gain of the proposed algorithm is also investigated and designed. Simulation results show that, in both single relay and multirelay selection systems, some outage probability gains by the proposed scheme can be obtained. In the comparison of the optimized power allocation scheme with the equal power allocation one, nearly 0.1695 gains are obtained in the ISHDAF single relay network at a total power of 2 dB, and about 0.083 gains are obtained in the HDAF relay selection system with 2 relays at a total power of 2 dB.
9
Yang, Ping, Weichao Kuang i Shanjin Wang. "Relay Selection for Dual-Hop Cooperative Ambient Backscatter Communication Systems". Sensors 23, nr 13 (21.06.2023): 5791. http://dx.doi.org/10.3390/s23135791.
Pełny tekst źródłaStreszczenie:
Previous works only focus on the optimization design for the dual-hop cooperative ambient backscatter communication (AmBC) system with single-relay selection. The impact of relay selection on the outage performance of dual-hop cooperative AmBC systems is still missing. Motivated by this, in this paper, we investigate the outage performance of a dual-hop cooperative AmBC system with single-relay selection, where the backscatter link shares the receiver with the cellular link and the harmful direct-link interference (DLI) is mitigated by using successive interference cancellation (SIC). In the system considered, the selected relay has dual functions. One is to forward message for the cellular link, and the other is to act as the radio-frequency (RF) source for the backscatter device (BD). Specifically, after proposing two novel single-relay selection schemes (RSSs), namely reactive RSS and proactive RSS, we derive the closed-form outage probability (OP) expressions for both RSSs, which can be performed in a distributed manner. To gain more insights, the asymptotic OPs at high signal-to-noise ratio (SNR) are explored and the outage performance comparison between the reactive RSS and proactive RSS are also provided. Results show that the proposed reactive RSS is outage-optimal among all possible single-relay selection schemes. The theoretical analysis is validated by Monte Carlo simulations. The results also show that the relay selection scheme, the number of relays, the location of BD, and the reflection coefficient of BD have great impact on the outage performance of cooperative AmBC systems.
10
Tran, Thanh-Nam, i Miroslav Voznak. "HD/FD and DF/AF with Fixed-Gain or Variable-Gain Protocol Switching Mechanism over Cooperative NOMA for Green-Wireless Networks". Sensors 19, nr 8 (18.04.2019): 1845. http://dx.doi.org/10.3390/s19081845.
Pełny tekst źródłaStreszczenie:
This article studied the application of multiple protocol switching mechanism (PSM) over cooperating Non-Orthogonal Multiple Access (NOMA) networks to minimize the probability of outage and maximize the system throughput and energy efficiency (EE). This study investigated six scenarios: (1) a cooperative NOMA system with half-duplex (HD) and decode-and-forward (DF) protocols at the relay; (2) a cooperative NOMA system with full-duplex (FD) and DF protocols at the relay; (3) a cooperative NOMA system with HD and amplification amplify-and-forward (AF) with fixed-gain (FG) protocols at the relay; (4) a cooperative NOMA system with HD and amplification AF with variable-gain (VG) protocols at the relay; (5) a cooperative NOMA system with FD and amplification AF with FG protocols at the relay; (6) a cooperative NOMA system with FD and amplification AF with VG protocols at the relay. Based on the results of analysis and simulations, the study determined the transmission scenario for best system performance. This paper also proposed a mechanism to switch between HD/FD and DF/AF with FG/VG protocols in order to improve the quality of service (QoS) for users with a weak conditional channel. This mechanism can be deployed in future 5G wireless network sensors. Finally, EE was also assessed in relation to future green-wireless networks (G-WNs).
11
Messadi, Oussama, Aduwati Sali, Vahid Khodamoradi, Asem A. Salah, Gaofeng Pan, Shaiful J. Hashim i Nor K. Noordin. "Optimal Relay Selection Scheme with Multiantenna Power Beacon for Wireless-Powered Cooperation Communication Networks". Sensors 21, nr 1 (29.12.2020): 147. http://dx.doi.org/10.3390/s21010147.
Pełny tekst źródłaStreszczenie:
Unlike the fixed power grid cooperative networks, which are mainly based on the reception reliability parameter while choosing the best relay, the wireless-powered cooperative communication network (WPCCN) and in addition to the reception reliability the transmission requirement consideration is important for relay selection schemes. Hence, enabling efficient transmission techniques that address high attenuation of radio frequency (RF) signals according to the distance without increasing the total transmission power is an open issue worth studying. In this relation, a multiantennas power beacon (PB) that assists wireless-powered cooperative communication network (PB-WPCCN) is studied in this paper. The communication between source and destination is achieved with the aid of multiple relays, where both the source and the multiple relays need to harvest energy from the PB in the first place to enable their transmission functionalities. A novel relay selection scheme is proposed, named as two-round relay selection (2-RRS), where a group of relays that successfully decode the source information is selected in the first round selection. In the second round, the optimal relay is selected to forward the recorded information to the destination. The proposed 2-RRS scheme is compared with two existing relay selection schemes, i.e., partial relay selection (PRS) and opportunistic relay selection (ORS). The analytical closed-form expressions of outage probability and average system throughput are derived and validated by numerical simulation. The comparison results between different relay selection schemes show: (I) The superiority of the proposed 2-RRS scheme as it achieves around 17% better throughput compared to the conventional ORS scheme and 40% better than the PRS scheme, particularly when PB transmit power is 10 dB; (II) The proposed 2-RRS scheme guarantees the lowest outage probability, especially when the PB is equipped with multiantennas and performs beamforming technique; (III) The optimal localisation of the PB between the source and N relays depends on the adopted relay selection scheme; (IV) The exhaustive search of the maximum system throughput value shows that the proposed 2-RRS scheme required shorter energy harvesting time compared to other schemes. The increase in energy harvesting time and number of relays do not necessarily reflect positively on the system throughput performance; hence tradeoffs should be taken into consideration.
12
Li, Yong Shuang, Qiu Feng Shang i Xue Mei Li. "Research on Cooperative Relay Transmission in Power Line Communication". Advanced Materials Research 659 (styczeń 2013): 79–82. http://dx.doi.org/10.4028/www.scientific.net/amr.659.79.
Pełny tekst źródłaStreszczenie:
In this paper, cooperative relay transmission in power line communication system is investigated. It is considered that channels between users and relays are disturbed by PLC noise. The half-duplex AF relaying model is used to measure the performance for the PLC system. The system performance under cooperative relaying is analyzed and compared. The PLC channel is considered as Middleton’s Class A noise model.
13
Panajotovic, Aleksandra, Nikola Sekulovic, Aleksandra Cvetkovic i Daniela Milovic. "Performance of cooperative multi-hop multiuser relaying networks". Serbian Journal of Electrical Engineering 15, nr 2 (2018): 213–24. http://dx.doi.org/10.2298/sjee1802213p.
Pełny tekst źródłaStreszczenie:
This paper presents both capacity and error performances of cooperative multi-hop multiuser relay system. All multi-hop cooperative relays in the system apply maximal-ratio combining (MRC) scheme, while signal transmission to end users is carried out using opportunistic scheduling algorithm. Numerical results for spectral efficiency and average symbol error probability (ASEP) for considered system are presented and discussed.
14
Chaoui, Slim, Omar Alruwaili, Chafaa Hamrouni, Aarif Alutaybi i Afif Masmoudi. "On the Performance of Coded Cooperative Communication with Multiple Energy-Harvesting Relays and Error-Prone Forwarding". Applied Sciences 13, nr 5 (24.02.2023): 2910. http://dx.doi.org/10.3390/app13052910.
Pełny tekst źródłaStreszczenie:
In this paper, we consider a coded cooperative communication network with multiple energy-harvesting (EH) relays. In order to adequately address the problem of error propagation due to the erroneous decoding at the relays, as in the case of conventional decode and forward (DF) relaying protocol, we propose coded cooperative schemes with hard information relaying (HIR) and soft information relaying (SIR) strategies. The performance of the relayed communication with EH relay depends crucially on the channel decoding capability at the relay, channel gains at the source–relay and relay–destination links, and ultimately on the power-splitting ratio of the relay EH receiver. The exact closed-form expression for the outage probability performance of the coded cooperative scheme with HIR strategy and relay selection (CC-HIR-RS) is derived for both cases, namely for constant and optimal power-splitting ratios. Concerning the coded cooperative scheme with SIR strategy, a Rayleigh Gaussian log likelihood ratio-based model is used to describe the soft estimated symbols at the output of the relay soft encoder. Directives are provided to determine the model parameters, and, accordingly, the signal-to-noise ratio (SNR) of the equivalent one-hop relaying channel is derived. A closed-form expression for the outage probability performance of the proposed coded cooperative scheme with SIR and relay selection (CC-SIR-RS) is derived. In addition, a fuzzy logic-based power-splitting scheme in EH relay applying SIR is proposed. The fading coefficients of the source–relay and relay–destination links and distance between source and relay node are considered as input parameters of the fuzzy logic system to obtain an appropriate power-splitting ratio that leads to a quasi-optimal SNR of the equivalent end-to-end channel. Monte Carlo simulations are presented to demonstrate the validity of the analytical results, and a comparison between the performance of the CC-HIR-RS scheme with constant and optimized power-splitting ratios and that of the CC-SIR-RS scheme with constant and fuzzy logic-based power-splitting ratios is provided.
15
Wang, Tao, Hou De Quan i Pei Zhang Cui. "Research on Relay Selection Based on Two-Hop Multi-Relay Networks". Applied Mechanics and Materials 347-350 (sierpień 2013): 2122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.2122.
Pełny tekst źródłaStreszczenie:
A relay selection criteria was proposed based on time division non-orthogonal cooperation, aiming at solving the problem of relay selection in the two-hop multi-relay cooperative communication to predigest the system design. The system BER (bit error rate) expression was obtained with its performance analysis under the condition of high SNR. Furthermore, computer simulations was conducted to show that the system diversity order is increased with the increase of the relay number under the condition of the distributed relay selection criterion, and diversity gain can be obtained significantly with the BER of the system significant decreasing.
16
Zhu, Kai Yan, Hong Yu Wang i Da Xing Qian. "Performance Analysis of Space-Time and Amplify-and-Forward Cooperative System". Advanced Materials Research 485 (luty 2012): 578–83. http://dx.doi.org/10.4028/www.scientific.net/amr.485.578.
Pełny tekst źródłaStreszczenie:
In this paper, we consider a space-time and amplify-and-forward(ST-AF) cooperative system which consists of two-antenna source, single-antenna relay and destination. Source transmits Alamouti space-time coding symbols to destination with cooperation of relay which adopts AF strategy. Closed-form symbol error rate(SER) is derived for the ST-AF system with PSK signals. Moreover, an SER approximation are developed to show the asymptotic performance of the ST-AF cooperative system in medium and high SNR regimes. For comparison, the SER approximation of another cooperative space-time coding(C-STC) scheme is also derived. Theoretical analysis shows that the ST-AF can obtain more diversity gain and achieve higher diversity order than C-STC. Finally, computer simulations validate the theoretical analysis.
17
Wen, Shuhuan, Baozhu Hu, Ahmad B. Rad, Xinbin Li, Huibin Lu i Jianhua Zhang. "Robust Nash Dynamic Game Strategy for User Cooperation Energy Efficiency in Wireless Cellular Networks". Mathematical Problems in Engineering 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/636159.
Pełny tekst źródłaStreszczenie:
Recently, there is an emerging trend of addressing “energy efficiency” aspect of wireless communications. It has been shown that cooperating users relay each other's information to improve data rates. The energy is limited in the wireless cellular network, but the mobile users refuse to relay. This paper presents an approach that encourages user cooperation in order to improve the energy efficiency. The game theory is an efficient method to solve such conflicts. We present a cellular framework in which two mobile users, who desire to communicate with a common base station, may cooperate via decode-and-forward relaying. In the case of imperfect information assumption, cooperative Nash dynamic game is used between the two users' cooperation to tackle the decision making problems: whether to cooperate and how to cooperate in wireless networks. The scheme based on “cooperative game theory” can achieve general pareto-optimal performance for cooperative games, and thus, maximize the entire system payoff while maintaining fairness.
18
Li, Suoping, Wenwu Liang, Vicent Pla, Nana Yang i Sa Yang. "Two-Stage Adaptive Relay Selection and Power Allocation Strategy for Cooperative CR-NOMA Networks in Underlay Spectrum Sharing". Applied Sciences 11, nr 21 (6.11.2021): 10433. http://dx.doi.org/10.3390/app112110433.
Pełny tekst źródłaStreszczenie:
In this paper, we consider a novel cooperative underlay cognitive radio network based on non-orthogonal multiple access (CR-NOMA) with adaptive relay selection and power allocation. In secondary networks, dedicated relay assistance and user assistance are used to achieve communication between the base station and the far (and near) user. Here, a two-stage adaptive relay selection and power allocation strategy is proposed to maximize the achievable data rate of the far user while ensuring the service quality of near user. Furthermore, the closed-form expressions of outage probability of two secondary users are derived, respectively, under interference power constraints, revealing the impact of transmit power, number of relays, interference threshold and target data rate on system outage probability. Numerical results and simulations validate the advantages of the established cooperation and show that the proposed adaptive relay selection and power allocation strategy has better outage performance.
19
AZMI, MUHAMMAD RAUDHI, MELINDA MELINDA i NASARUDDIN NASARUDDIN. "Analisis Kinerja Jaringan Hybrid Kooperatif Device-to-Device 5G menggunakan Teknik Pemilihan Relay Reaktif". ELKOMIKA: Jurnal Teknik Energi Elektrik, Teknik Telekomunikasi, & Teknik Elektronika 8, nr 1 (31.01.2020): 178. http://dx.doi.org/10.26760/elkomika.v8i1.178.
Pełny tekst źródłaStreszczenie:
ABSTRAK
Sistem komunikasi kooperatif device-to-device (D2D) merupakan salah satu strategi peningkatan kecepatan data dan efisiensi energi. Pada sistem kooperatif, mekanisme relay merupakan faktor penting dalam meneruskan informasi. Model jaringan merupakan isu penting untuk meningkatkan kecepatan, kinerja dan efisiensi energi pada sistem. Oleh sebab itu, makalah ini menganalisis kinerja jaringan hybrid kooperatif D2D pada teknologi 5G menggunakan teknik pemilihan relay reaktif atau reactive relay selection (RRS). Beberapa parameter kinerja penting telah simulasikan, seperti model jaringan, SNR, BER dan throughput. Hasil simulasi menunjukkan bahwa jaringan kooperatif hybrid-relay dengan RRS menghasilkan nilai BER yang lebih kecil dan throughput yang lebih tinggi dibandingkan model multi-relay dan multi-hop relay. Dengan demikian, jaringan hybrid-relay dengan pemilihan relay lebih efisien dibandingkan jaringan lainnya.
Kata kunci: sistem komunikasi kooperatif, pemilihan relay reaktif, multi-hop, multi-relay, hybrid-relay.
ABSTRACT
A device-to-device (D2D) cooperative communication system is one of the strategies to increase data speed and energy efficiency. In a cooperative system, the relay mechanism is an important factor in forwarding information. A network model is an important issue to increase the speed, performance and energy efficiency of the system. Therefore, this paper analyzes the performance of D2D cooperative hybrid networks on 5G technology using reactive relay selection (RRS)
techniques. Some important performance parameters have been simulated, such as network models, SNR, BER and throughput. Simulation results show that hybridrelay cooperative networks with RRS produce smaller BER values and higher throughput compared to multi-relay and multi-hop relay models. Thus, hybridrelay networks with relay selection are more efficient than other networks.
Keywords: cooperative communication system, reactive relay selection, multihop, multi-relay, hybrid-relay.
20
Hwang, Kyu-Sung, i MinChul Ju. "Performance Analysis of Output Threshold-Based Incremental Multiple-Relay Combining Scheme with Adaptive Modulation for Cooperative Networks". Mathematical Problems in Engineering 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/6310345.
Pełny tekst źródłaStreszczenie:
In this paper, we propose an output threshold-based incremental multiple-relay combining scheme for cooperative amplify-and-forward relay networks with nonidentically distributed relay channels. Specifically, in order to achieve the required performance, we consider both conventional incremental relaying and multiple-relay selection where relays are adaptively selected based on a predetermined output threshold. Moreover, the adaptive modulation technique is adopted by our proposed scheme for satisfying both the spectral efficiency and the required error rate. For the proposed scheme, we first derive an upper bound of the output combined signal-to-noise ratio and then provide its statistics such as cumulative distribution function (CDF), probability density function (PDF), and moment generating function (MGF) over independent, nonidentically distributed Rayleigh fading channels. Additionally, we analyze the system performance in terms of average spectral efficiency, average bit error rate, outage probability, and system complexity. Finally, numerical examples show that our proposed scheme leads to a certain performance improvement in the cooperative networks.
21
Do, Dinh-Thuan, i Minh-Sang V. Nguyen. "Relay Selection-aware Non-orthogonal Multiple Access Networks: Direct and Relaying Mode". Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 13, nr 3 (18.05.2020): 348–54. http://dx.doi.org/10.2174/2352096512666181130164755.
Pełny tekst źródłaStreszczenie:
Objective: In this paper, Decode-and-Forward (DF) mode is deployed in the Relay Selection (RS) scheme to provide better performance in cooperative downlink Non-orthogonal Multiple Access (NOMA) networks. In particular, evaluation regarding the impact of the number of multiple relays on outage performance is presented. Methods: As main parameter affecting cooperative NOMA performance, we consider the scenario of the fixed power allocations and the varying number of relays. In addition, the expressions of outage probabilities are the main metric to examine separated NOMA users. By matching related results between simulation and analytical methods, the exactness of derived formula can be verified. Results: The intuitive main results show that in such cooperative NOMA networks, the higher the number of relays equipped, the better the system performance can be achieved. Conclusion: DF mode is confirmed as a reasonable selection scheme to improve the transmission quality in NOMA. In future work, we will introduce new relay selections to achieve improved performance.
22
Altubaishi, Essam Saleh. "Effect of controlling maximum-SNR-based relay selection strategy in cooperative wireless communication systems". Indonesian Journal of Electrical Engineering and Computer Science 22, nr 1 (1.04.2021): 335. http://dx.doi.org/10.11591/ijeecs.v22.i1.pp335-341.
Pełny tekst źródłaStreszczenie:
<span>Relay selection strategy under maximum-signal-to-noise ratio (MAX-SNR) criterion was proven to maximize performance but at the expense of losing fairness among the cooperative relays. In this work, the effect of controlling the MAX-SNR criterion on the spectral efficiency of cooperative wireless communication system with adaptive modulation is investigated. Specifically, the probability density function (PDF) of the end-to-end SNR for the considered system is derived when the controlled selection criterion is considered. Base on that PDF, the average spectral efficiency is then derived and investigated. The results show how the spectral efficiency of the system deteriorates as controlling the selection of a relay. Furthermore, the results of Monte Carlo simulation validate the derived expression.</span>
23
Sehito, Nabila, Shouyi Yang, Abdullh G. Al Harbi, Muhammad Inam Abbasi, Muhammad Abbas Khan, Muhammad Amir Khan i Mian Muhammad Kamal. "Secrecy Performance by Power Splitting in Cooperative Dual-Hop Relay Wireless Energy Harvesting". Wireless Communications and Mobile Computing 2022 (14.05.2022): 1–7. http://dx.doi.org/10.1155/2022/8367107.
Pełny tekst źródłaStreszczenie:
In wireless communication systems, for secure communication between a transmitter and receiver over the communication channel, the physical layer security is widely utilized. The paper presents a dual-hop wireless full-duplex relay (FDR) network with a source relay and destination relay between two nodes and listening devices. The relay and source use energy harvesting to gain energy from power beacon. Two cooperative techniques are utilized to investigate the amplify-forward (AF) and decode-forward (DF) secrecy capacity in the energy harvesting power splitting system. It is shown that the secrecy performance of an AF relay is better than the secrecy performance of a DF relay in the given form. At 40-meter distance between the relay and the eavesdropper in an energy harvesting system, the AF relay outperforms the DF relay. The simulation is performed using the Monte-Carlo method in MATLAB.
24
Li, Jie, Jianrong Bao, Shenji Luan, Bin Jiang i Chao Liu. "Power Optimized Single Relay Selection with an Improved Link-Adaptive-Regenerative Protocol". Journal of Electrical and Computer Engineering 2018 (2.07.2018): 1–8. http://dx.doi.org/10.1155/2018/8364594.
Pełny tekst źródłaStreszczenie:
To improve the reliability and efficiency in cooperative communications, a power optimized single relay selection scheme is proposed by increasing the diversity effort with an improved link-adaptive-regenerative (ILAR) protocol. The protocol determines the forwarding power of a relay node by comparing the signal-to-noise ratio (SNR) at both sides of the node; thus it improves the power efficiency. Moreover, it also proposes a single relay selection strategy to maximize the instantaneous SNR product, which ensures the approximate best channel link quality for good relay forwarding. And the system adjusts the forwarding power in real time and also selects the best relay node participated in the cooperative forwarding. In addition, the cooperation in the protocol is analyzed and the approximate expression of the bit-error-rate (BER) and the outage probability at high SNRs are also derived. Simulation results indicate that the BER and outage probability of the relay selection scheme by the ILAR protocol outperform other contrast schemes of current existing protocols. At BER of 10−2, the proposed scheme with ILAR protocol outperforms those of the decoded-and-forward (DF), the selected DF (SDF), and the amplify-and-forward (AF) protocols by 3.5, 3.5 and 7 dB, respectively. Moreover, the outage probability of the relay system decreases with the growth of the relay number. Therefore, the proposed relay selection scheme with ILAR strategies can be properly used in cooperative communications for good reliability and high power efficiency.
25
Alkhawatrah, Mohammad. "Buffer-Aided Cooperative Millimeter Waves for IOT Networks". Journal of Electrical and Computer Engineering 2022 (30.10.2022): 1–8. http://dx.doi.org/10.1155/2022/7474679.
Pełny tekst źródłaStreszczenie:
Millimeter-wave (mm-Wave) communications is a promising technology for the next wireless generations and applications such as IoT networks because of its massive bandwidth which increases the system capacity. However, mm-wave is susceptible to huge path loss and obstacle blocking, and this is largely narrowing the coverage of the mm-wave signals. Therefore, several techniques are used to enhance mm-wave performance such as multiple-input multiple-output (MIMO) and cooperative solutions such as relays. For instance, traditional relaying techniques (without buffers) are utilized to mitigate mm-wave path loss and blocking, as it provides an alternative path that could have lower path loss and it could help in avoiding obstacles. Nonetheless, traditional relaying techniques are outperformed by buffer-aided relaying techniques which achieve higher throughput and lower outage in the microwave frequencies. In this paper, we propose utilizing buffer-aided relays with a finite buffer-size instead of conventional relays in mm-wave networks motivated by the positive impact of the buffer-aided relay in lower frequency bands (microwave band). In the simulations, all sources, relays, blockages, and users are distributed in the network as a Poisson point process with various densities. Simulation experiments show that the proposed relay-assisted mm-wave network with buffering capabilities outperforms the conventional relay in both throughput and coverage and achieves about 3 dB gain. This superiority of the proposed solution holds in different scenarios such as increasing the ratio of the blockages or decreasing the ratio of relays. In particular, employing buffer-aided relays has almost the same effect of doubling the number of conventional relays, which is cost and spatial effective. Furthermore, in the majority of buffer-aided relays studies, the impractical infinite buffer-size is considered; however, the proposed solution utilizes a practical finite buffer-size with prioritizing transmission, and the results show that the practical solution can outperform the infinite buffer-size solution in the mm-wave networks.
26
Jain, Preksha, Akhil Gupta, Neeraj Kumar, Gyanendra Prasad Joshi i Woong Cho. "Performance Evaluation of Cooperative OMA and NOMA Systems in 6G Deployment Scenarios". Sensors 22, nr 11 (24.05.2022): 3986. http://dx.doi.org/10.3390/s22113986.
Pełny tekst źródłaStreszczenie:
Optimization of the energy efficiency, fairness, and rates of the system is a vital part of communication systems. Multiple access techniques have a huge potential to enhance such performance parameters. This paper studies the performance of NOMA and OMA systems in a singular cell environment, where the cellular users are distributed randomly, and cooperative relays are considered for better system reliability. The relay nodes forward the signals to the cell-edge users. This paper considers a practical scenario where all the relay equipment is distributed with non-uniform battery power levels. The performance of OMA and NOMA schemes is compared based on the key performance indicators: sum rate, fairness, and energy efficiency. The fairness factor determines fairness in the allocation of resources to all the system’s users. The performance of the two schemes is assessed in three deployment scenarios: urban, suburban, and rural scenarios. Through numerical results, it is proved that the performance of the NOMA dominates the OMA scheme.
27
Wang, Yi Xuan, Shou Yi Yang, Tao Ge i Ai Hua Zhang. "The Research on Sparse Channel Estimation in Multi-Relay Cooperative Communication System". Applied Mechanics and Materials 556-562 (maj 2014): 5153–58. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.5153.
Pełny tekst źródłaStreszczenie:
In a frequency selective fading environment amplify and forward relay system, the channel estimation algorithm and least squares (LS) estimation of mean square error is relatively high. And when using the compressed sensing (CS) which was proposed recently in orthogonal matching pursuit algorithm (OMP) for the single relay channel and multi relay system estimation, in order to reduce the mean square error of the system. In multi-relay cooperative communication system, allocated the power to the relay node, then respectively using the LS and OMP for channel estimation. The results show that, the orthogonal matching pursuit algorithm can greatly reduce the system mean square error, and the same channel estimation algorithm was used for the relay power allocation is also effectively reduce the estimation error, to further improve the accuracy of channel estimation.
28
Bao, Song Jian, Shou Liang Yang i Ling Gang Zeng. "Space-Time Block Coding Cooperation Improved Algorithm Based on LTE-Advanced". Applied Mechanics and Materials 401-403 (wrzesień 2013): 1998–2002. http://dx.doi.org/10.4028/www.scientific.net/amm.401-403.1998.
Pełny tekst źródłaStreszczenie:
Abstract. LTE-Advanced is positioned on the higher data rates and a greater system capacity. In order to meet the goal, LTE-Advanced will undoubtedly introduce new wireless technology. The relay technology as key candidate technology of LTE-Advanced system can brings greater coverage and system capacity for residential area. Cooperative relay signal processing methods include amplification forward relay and decoding relay. So, proposed improve the cooperative relay based on the space-time coding, introduced precoding in front of the relay data sent and find out the optimal space-time coding transmission. Through the computer simulation, fully verified the feasibility of improved space-time coding transmission algorithm.
29
Na, Yu-Jin, Won-Seok Lee, Jong-Gyu Ha i Hyoung-Kyu Song. "Relay Selection Scheme Enhancing Reliability Based on MIMO-OFDM System". International Journal of Signal Processing Systems 9, nr 1 (marzec 2021): 7–10. http://dx.doi.org/10.18178/ijsps.9.1.7-10.
Pełny tekst źródłaStreszczenie:
In this paper, a relay selection scheme is proposed in the Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. The conventional relay selection schemes in the wireless cooperative communication system have high implementation complexity and overhead. The proposed scheme is an adaptive relay selection scheme using Singular Value Decomposition (SVD) to select a relay with channel coefficients that maximize channel capacity. Proposed scheme uses combining factor with singular value in order to combine received signal. Simulation result shows that the proposed scheme improves the Bit Error Rate (BER) performance, compared with the conventional schemes. The proposed scheme with combining factors has enhanced BER performance than the conventional schemes.
30
Yang, Dongmei, Cheng Li, Baoquan Ren, Hongjun Li i Kefeng Guo. "Analysis of relay selection schemes in underlay cognitive radio non-orthogonal multiple access networks". International Journal of Distributed Sensor Networks 18, nr 5 (maj 2022): 155014772110663. http://dx.doi.org/10.1177/15501477211066304.
Pełny tekst źródłaStreszczenie:
This article investigates the impacts of relay selection schemes on cooperative underlay cognitive radio non-orthogonal multiple access networks, where the partial relay selection scheme, the max–min relay selection scheme and the two-stage relay selection scheme are applied in the network. Moreover, decode-and-forward protocol is used at the transmission relays. What’s more, in order to show the effect of the schemes on the considered network, the closed-form expressions and asymptotic expressions for the outage probability of the system are derived. Furthermore, the outage performance under the effect of perfect and imperfect successive interference cancellation is analysed. Numerical results are given to illustrate the impacts of the relay selection schemes, the number of relays, the residual interference factor and the power allocation factor on the outage performance. Finally, Monte Carlo simulations are presented to validate the accuracy of the numerical results.
31
Liu, Kang, Qi Zhu i Ying Wang. "Outage Analysis and Power Allocation Optimization for Multiple Energy-Harvesting Relay System Using SWIPT". Mobile Information Systems 2018 (13.09.2018): 1–11. http://dx.doi.org/10.1155/2018/7102427.
Pełny tekst źródłaStreszczenie:
Energy harvesting (EH) combined with cooperative relying plays a promising role in future wireless communication systems. We consider a wireless multiple EH relay system. All relays are assumed to be EH nodes with simultaneous wireless and information transfer (SWIPT) capabilities, which means the relays are wirelessly powered by harvesting energy from the received signal. Each EH node separates the input RF signal into two parts which are, respectively, for EH and information transmission using the power splitting (PS) protocol. In this paper, a closed-form outage probability expression is derived for the cooperative relaying system based on the characteristic function of the system’s probability density function (PDF) with only one relay. With the approximation of the outage probability expression, three optimization problems are built to minimize the outage probability under different constraints. We use the Lagrange method and Karush–Kuhn–Tucker (KKT) condition to solve the optimization problems to jointly optimize the relay’s PS factors and the transmit power. Numerical results show that our derived expression of the outage probability is accuracy and gives insights into the effect of various system parameters on the performance of protocols. Meanwhile, compared with the no optimal condition, our proposed optimization algorithms can all offer superior performance under different system constraints.
32
Gheth, Waled, Khaled M. Rabie, Bamidele Adebisi, Muhammad Ijaz i Georgina Harris. "Performance Analysis of Cooperative and Non-Cooperative Relaying over VLC Channels". Sensors 20, nr 13 (30.06.2020): 3660. http://dx.doi.org/10.3390/s20133660.
Pełny tekst źródłaStreszczenie:
The line-of-sight (LoS) channel is one of the requirements for efficient data transmission in visible-light communications (VLC), but this cannot always be guaranteed in indoor applications for a variety of reasons, such as moving objects and the layout of rooms. The relay-assisted VLC system is one of the techniques that can be used to address this issue and ensures seamless connectivity. This paper investigates the performance of half-duplex (HD) conventional DF relay system and cooperative systems (i.e., selective DF (SDF) and incremental DF (IDF)) over VLC channels in terms of outage probability and energy consumption. Analytical expressions for both outage probability and the minimum energy-per-bit performance of the aforementioned relaying systems are derived. Furthermore, Monte Carlo simulations are provided throughout the paper to validate the derived expressions. The results show that exploiting SDF and IDF relaying schemes can achieve approximately 25% and 15% outage probability enhancement compared to single-hop and DF protocols, respectively. The results also demonstrate that the performance of the single-hop VLC system deteriorates when the end-to-end distances become larger. For example, when the vertical distance is 3.5m, the single-hop approach consumes 20%, 40% and 45% more energy in comparison to the DF, SDF, and IDF approaches, respectively.
33
Alkhayyat, Ahmed. "Joint Next-Hop/Relay Selection for Distributive Multihop Cooperative Networks". Discrete Dynamics in Nature and Society 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/613168.
Pełny tekst źródłaStreszczenie:
Cooperative networks that use adjacent nodes to relay hearing data are employed as an effective technique to deal with channel fading, thereby enhancing the network performances. Next-hop and relay nodes selection schemes determine the optimal next-hop node toward the destination and relay node between the source and the optimal next-hop and/or destination. Offering joint next-hop and relay node selection in distributive multihop cooperative networks will enable the source to select the optimal next-hop node and relay node that can improve the system performance. In this paper, we propose a joint next-hop node and relay node selection (JNRS) protocol for wireless distributive multihop cooperative networks. The goal of JNRS is to reduce the spectral efficiency loss and outage probability. Analysis results show that JNRS can enhance the cooperative networks performance under general conditions compared to cooperative networks without the JNRS protocol.
34
Lin, Rui, Philippa A. Martin i Desmond P. Taylor. "Cooperative Signaling with Soft Information Combining". Journal of Electrical and Computer Engineering 2010 (2010): 1–5. http://dx.doi.org/10.1155/2010/530190.
Pełny tekst źródłaStreszczenie:
We propose a Decode-and-Forward (DF) scheme using distributed Turbo code (DTC) for a three-node (source, relay, and destination) wireless cooperative communication system. The relay decodes, then interleaves, and reencodes the decoded data. It then forwards the reencoded packet and its instantaneous receive SNR to the destination. The performances using both ideal and quantized SNR are studied. The destination uses a modified metric within a Turbo decoding algorithm to scale the soft information calculated for the relay code. The proposed scheme is simple to implement and performs well.
35
Chen, Haiqiang, Dongju Yu i Xiao Ma. "Cooperative Signal Constellation for LDPC-Coded Relay System". IEEE Communications Letters 15, nr 7 (lipiec 2011): 704–6. http://dx.doi.org/10.1109/lcomm.2011.060111.110721.
Pełny tekst źródła
36
Chopra, Khyati, Ranjan Bose i Anupam Joshi. "Secrecy Outage Performance of Cognitive Radio Network with Selection Combining at Eavesdropper". Recent Advances in Computer Science and Communications 13, nr 5 (5.11.2020): 987–98. http://dx.doi.org/10.2174/2213275912666190807122631.
Pełny tekst źródłaStreszczenie:
Background:: Based on the idea of cooperative communication, recently a lot of attention has been drawn to cooperative spectrum access for the secure information transmission in a Cognitive Radio Network (CRN). Security is one of the most important aspects of these networks, as due to their open and dynamic nature, they are extremely vulnerable to malicious behavior. Cooperative cognitive radio has emerged as a dynamic spectrum access technique, where an unlicensed (secondary) user is allowed to simultaneously access the licensed channels dedicated to a Primary User (PU), as long as the Quality of Service (QoS) of primary communication is not affected. Method:: This paper investigates the secrecy outage performance of threshold-based cognitive decode-andforward relay network, with interference constraints from primary licensed user. Threshold-based relaying is considered where; the source message is successfully decoded by the relay, only if the received SNR satisfies the particular threshold. Outage probability expressions have been derived for the worst-case scenario, where only the eavesdropper can achieve the advantage of diversity. The Selection Combining (SC) diversity scheme is employed only at the secondary eavesdropper. Results:: The system secrecy performance is better for SC diversity scheme at the eavesdropper than Maximal Ratio Combining (MRC) diversity scheme, as MRC has better diversity performance than SC. We have shown that the improvement in desired secrecy rate, predetermined threshold, eavesdropper channel quality and interference constraints affect the secrecy performance of the cognitive radio system. The outage probability decreases accordingly with an increase in the maximum tolerable interference level at primary destination. The outage probability of Optimal relay Selection (OS) scheme is derived for a multi-relay system, when either the Instantaneous Channel State Information (ICSI) or the Statistical Channel State Information (SCSI) is available. We have shown that the secrecy performance of the OS with ICSI of the system is better than with SCSI. Also, the OS improves the performance of the multi-relay system, when the number of relays is increased. Conclusion:: The secrecy outage probability of threshold-based DF underlay cognitive relay network is evaluated. Both interference and maximum transmit power constraints are considered at secondary source and secondary relay. Also, the relay can successfully decode the message, only if it meets the pre-defined threshold. We have investigated the performance of MRC and SC diversity schemes at the secondary eavesdropper and have shown that the system secrecy performance is better for SC than MRC, as MRC has better diversity performance than SC. We have shown that the system secrecy performance is significantly affected by the required secrecy rate, pre-defined threshold, interference constraints and choice of diversity scheme (MRC/SC) at the eavesdropper. The outage probability of OS scheme is derived for a multi-relay system, when either the ICSI or the SCSI is available. We have shown that the secrecy performance of the OS with ICSI of the system is better than with SCSI. Also, the OS improves the performance of the multi-relay system, when the number of relays is increased.
37
Wang, Min, i Hao Zhang. "Performance Analysis of 60GHz Cooperative Communication System with Directional Transmission". Advanced Materials Research 1049-1050 (październik 2014): 2020–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.2020.
Pełny tekst źródłaStreszczenie:
60GHz wireless communication is a promising technology for multi-gigabit communication in future home networks. It brings possibility of achieving in-door high-definition multimedia applications with high-speed and low-delay experience. However, to maintain the network connectivity with 60GHz links, which are susceptible to propagation and penetration losses, is a major challenge. The quality and robustness of 60GHz links can be effectively improved by employing relay nodes or cooperative nodes in the network. In this paper, taking into consideration the directional transmission character of 60GHz system, we conduct performance analysis and simulations for the 60GHz cooperative communication system. Two cooperative forwarding approaches are analyzed and compared, and the optimal position of the cooperative relay node is proposed.
38
Yan, Hui, i Zhong Pei Zhang. "A Low-Complexity Algorithm of Joint Multiple Frequency Offsets and Channels Estimation in Cooperative Relay Systems". Advanced Materials Research 748 (sierpień 2013): 1046–50. http://dx.doi.org/10.4028/www.scientific.net/amr.748.1046.
Pełny tekst źródłaStreszczenie:
A low complexity joint estimator of multiple CFOs and Channels is presented in cooperative relay systems. The new algorithm first utilizes correlation-based frequency estimator to get CFOs initial estimation, and then serial interference cancellation based on correlation properties of training sequence in different relays is done to obtain the initial channel estimation. Moreover, a parallel iteration scheme with interference cancellation is proposed to reduce time complexity of the traditional serial iteration. In the overall process, matrix inversion is avoided. Thus, the complexity of the proposed algorithm in both time and computation is much less than the existing algorithms. In last, simulation results verify the iterative algorithm achieves a good performance in Decode and Forward (DF) relay system.
39
Huynh, Tan-Phuoc, Pham Ngoc Son i Miroslav Voznak. "Secrecy Performance of Underlay Cooperative Cognitive Network Using Non-Orthogonal Multiple Access with Opportunistic Relay Selection". Symmetry 11, nr 3 (15.03.2019): 385. http://dx.doi.org/10.3390/sym11030385.
Pełny tekst źródłaStreszczenie:
In this paper, an underlay cooperative cognitive network using a non-orthogonal multiple access (UCCN-NOMA) system is investigated, in which the intermediate multiple relays help to decode and forward two signals x 1 and x 2 from a source node to two users D1 and D2, respectively, under wiretapping of an eavesdropper (E). We study the best relay selection strategies by three types of relay selection criteria: the first and second best relay selection is based on the maximum channel gain of the links R i -D 1 , R i -D2, respectively; the third one is to ensure a minimum value of the channel gains from the R i -E link. We analyze and evaluate the secrecy performances of the transmissions x 1 and x 2 from the source node to the destination nodes D1, D2, respectively, in the proposed UCCN-NOMA system in terms of the secrecy outage probabilities (SOPs) over Rayleigh fading channels. Simulation and analysis results are presented as follows. The results of the (sum) secrecy outage probability show that proposed scheme can realize the maximal diversity gain. The security of the system is very good when eavesdropper node E is far from the source and cooperative relay. Finally, the theoretical analyses are verified by performing Monte Carlo simulations.
40
Hao, Wanming, Shouyi Yang i Wanliang Hao. "Relay Selection and Subcarrier-Pair Based Energy-Efficient Resource Allocation for Multirelay Cooperative OFDMA Networks". International Journal of Antennas and Propagation 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/461713.
Pełny tekst źródłaStreszczenie:
Energy-efficient resource allocation is investigated for a relay-based multiuser cooperation orthogonal frequency division multiple access (OFDMA) uplink system with amplify-and-forward (AF) protocol for all relays. The objective is to maximize the total energy efficiency (EE) of the uplink system with consideration of some practical limitations, such as the individual power constraint for the users and relays and the quality of service (QoS) for every user. We formulate an energy-efficient resource allocation problem that seeks joint optimization of subcarrier pairing, relay selection, subcarrier assignment, and power allocation. Unlike previous optimization throughput models, we transform the considered EE problem in fractional form into an equivalent optimal problem in subtractive form, which is solved by using dual decomposition and subgradient methods. To reduce computation costs, we propose two low-complexity suboptimal schemes. Numerical studies are conducted to evaluate the EE of the proposed algorithms.
41
Wang, Zhenling, i Dawei Qiao. "Cooperative NOMA system with incremental relaying over Nakagami-m fading channels". International Journal of Distributed Sensor Networks 18, nr 1 (styczeń 2022): 155014772110726. http://dx.doi.org/10.1177/15501477211072699.
Pełny tekst źródłaStreszczenie:
In our article, we apply incremental relay to the cooperative non-orthogonal multiple access network, in which the incremental relay employs amplify and forward protocol. The main communication process of the system is that one base station transmits messages to multiple non-orthogonal multiple access users with the assistance of incremental relay. In addition, we deeply analyze the outage behavior of the incremental cooperative non-orthogonal multiple access system over Nakagami- m fading channels. Specifically, the exact and asymptotic closed-form expressions of outage probabilities are all derived for paired users u n and u f, which are nearby and distant user, respectively. On this basis, the diversity orders of the paired users u n and u f are also acquired, which are μ ( n+ f+1) and μ( f+1). We also investigate the conventional cooperative non-orthogonal multiple access system, which serves as a benchmark of the incremental cooperative non-orthogonal network. Through the proof, we can conclude that the outage behavior of the distant u f has been improved by adopting incremental relay. Finally, the performance of the system is simulated. The following conclusions can be drawn from the numerical simulation results: (1) the outage performance and throughput of the system have been significantly improved by using the incremental relay protocol; (2) as the multipath fading [Formula: see text] increases, the outage performance of the system becomes better; and (3) the greater the difference in channel gain between paired users, the incremental cooperative non-orthogonal system can achieve better outage performance.
42
S. Al-kahtani, Mohammed. "A Review of Relay Assignment Problem in the Cooperative Wireless Sensor Networks". Electronics 9, nr 3 (6.03.2020): 443. http://dx.doi.org/10.3390/electronics9030443.
Pełny tekst źródłaStreszczenie:
The relay selection is a promising approach of maximizing the diversity gain achieved in the cooperative wireless sensor networks. In the cooperative networks, the proper selection of relay node is a challenging task. The proper selection of relay nodes not only improves the source–destination performance, but also maximizes the overall system performance. There are many factors involved in designing a relay selection algorithm. The different relay selection algorithms have different focus, criteria, objective, mechanism, and performance issues. In this article, several relay assignment algorithms have been analyzed to show the effectiveness of channel capacity, power allocation, coverage expansion and interference mitigation in term of proper relay selection schemes. Moreover, this paper discusses some relay selection schemes, their challenging issues, limitations, performance criteria, and mechanisms. This article also highlights the significant design issues of relay selection methods and compares them that are appropriate in the cooperative wireless sensor networks.
43
He, Xianwen, Gaoqi Dou i Jun Gao. "Channel Estimation for OFDM-Based Amplify-and-Forward Cooperative System Using Relay-Superimposed Pilots". International Journal of Digital Multimedia Broadcasting 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/9618147.
Pełny tekst źródłaStreszczenie:
For the OFDM-based Amplify-and-Forward cooperative system, a novel relay-superimposed pilot strategy is proposed, where the source pilot symbols are frequency division multiplexed to estimate the cascaded channel while relay pilot sequence is superimposed onto the top of the cooperative data stream for second-hop channel estimation. This method avoids the loss of data rate for additional pilot subcarriers but results in the interference of unknown cooperative data. To remove the interference of cooperative data during the estimation of second-hop channel, the Cooperative Interference Cancelation scheme assisted by cooperative data from direct link is proposed. We derive the approximated lower bound for the MSE of second-hop channel estimation. Simulation results are presented to validate the performance of the proposed schemes.
44
Mohammed, Ali Abdulwahhab, Li Yu, Li Yu, Manar Al-Kali, Manar Al-Kali, Desheng Wang i Desheng Wang. "Performance Analysis of Amplify and Forward Cooperative Networks over Rayleigh and Nakagami-m Channels based Relaying Selection". INTERNATIONAL JOURNAL OF COMPUTERS & TECHNOLOGY 15, nr 5 (24.03.2016): 6749–56. http://dx.doi.org/10.24297/ijct.v15i5.1638.
Pełny tekst źródłaStreszczenie:
In this paper investigates the performance, analysis of amplify and forward (AF) cooperative networks with the relay selection over  Nakagami-m and Rayleigh fading channels and  M-ary phase shift keying (MPSK) modulations. New closed form expressions are derived for the general cases of Rayleigh and Nakagami-m fading channels. cumulative density function (CDF), probability density function (PDF) of the end –to - end signal –to – nois ratio (SNR) of a dual-hop opportunistic AF relaying system, moment generating function (MGF), symbol error rate (SER) and outage probability (Pout). and the first closed-form study for opportunistic AF relaying system where the best node is selected from a number of candidate intermediate nodes to relay the data signal between the source and the destination. Simulation results reveal that the PDF , CDF, Pout and SER performance downgrades either the m parameter or the number of relays increases. Our simulations compared between Rayleigh and Nakagami-m links for a different number of relays. In addition, different modulation techniques are examined to show the effect of the modulation scheme which was used over Rayleigh and Nakagami-m fading channels on the cooperative networks. The obtained results proved the impact of m parameters, relay selection and modulation index on the pout and SER performance.
45
Dong, Luo Bing, Ke Chu Yi, Zhi Qiang Li i Pei Yi Shen. "Analysis on Cooperative GBN-ARQ Performance in TDMA Single Source and Single Relay Network". Key Engineering Materials 474-476 (kwiecień 2011): 1966–73. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.1966.
Pełny tekst źródłaStreszczenie:
This paper proposes a new cooperative GBN-ARQ（Go-Back-N Cooperative Automatic Repeat Request: GBN-CARQ）algorithm which is suitable for the single source and single relay wireless communication system based on TDMA, establishing the queuing model of single source and single relay wireless communication system based on TDMA and providing the expressions of its throughput and delay performance. By comparing with GBN-ARQ algorithm and normal cooperative ARQ（Cooperative ARQ：CARQ）algorithm, it is shown that GBN-CARQ algorithm has better average throughput performance.
46
Li, Jheng-Sian, Jyh-Horng Wen, Chung-Hua Chiang i Chien-Erh Weng. "Performance on Multiple Pilot-Based Grouping Methods in Satellite-Terrestrial Cooperative Wireless Networks". Electronics 11, nr 3 (30.01.2022): 430. http://dx.doi.org/10.3390/electronics11030430.
Pełny tekst źródłaStreszczenie:
The grouping method is an efficient transmitting strategy in a spatial diversity system. In this paper, relay-based grouping methods in satellite terrestrial cooperative wireless networks are proposed. The proposed methods focus on finding out the best two signals received from relay stations in a user’s neighborhood and use the advantage of space diversity to overcome the effect of channel fading. A grouping method, called the pilot-based grouping method was proposed in our previous work. In order to improve the grouping success rate and the channel capacity, a modified grouping method is proposed. In addition, for a single relay the modified grouping method can achieve better results than the pilot-based grouping method. In the end, several analysis strategies of the grouping method for multimedia broadcast and multicast services in satellite terrestrial cooperative networks are proposed. The simulation results show the performance improvement and the system evaluation for different quality of services in the demanded relay-based cooperative networks. The proposed modified grouping methods can be widespread in any relay-based cooperative networks.
47
Pan, Huifang, i Qi Zhu. "Energy-Efficient Power Allocation in Non-Linear Energy Harvesting Multiple Relay Systems". Algorithms 14, nr 5 (17.05.2021): 155. http://dx.doi.org/10.3390/a14050155.
Pełny tekst źródłaStreszczenie:
In this paper, to maximize the energy efficiency (EE) in the two-hop multi-relay cooperative decoding and forwarding (DF) system for simultaneous wireless information and power transmission (SWIPT), an optimal power allocation algorithm is proposed, in which the relay energy harvesting (EH) adopts a nonlinear model. Under the constraints, including energy causality, the minimum transmission quality of information and the total transmission power at the relays, an optimization problem is constructed to jointly optimize the transmit power and power-splitting (PS) ratios of multiple relays. Although this problem is a nonlinear fractional programming problem, an iterative algorithm is developed to obtain the optimal power allocation. In particular, the joint power allocation at multiple relays is first decoupled into a single relay power allocation, and then single-relay power allocation is performed by the Dinkelbach iteration algorithm, which can be proven that it is a convex programming problem. Its closed form solutions for different polylines of EH models are obtained by using mathematical methods, such as monotonicity, Lagrange multipliers, the KKT condition and the Cardan formula. The simulation results show the superiority of the power allocation algorithm proposed in this paper in terms of EE.
48
Wang, Haiyong, Geng Yang, Yiran Gu, Jian Xu i Zhixin Sun. "A Novel Cooperative ARQ Method for Wireless Sensor Networks". International Journal of Distributed Sensor Networks 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/102326.
Pełny tekst źródłaStreszczenie:
In wireless sensor networks, cooperative communication can combat the effects of channel fading by exploiting diversity gain achieved via cooperation communication among the relay nodes. A cooperative automatic retransmission request (ARQ) protocol based on two-relay node selection was proposed in this paper. A novel discrete time Markov chain model in order to analyze the throughput and energy efficiency was built, and system throughput and energy efficiency performance of proposed protocol and traditional ARQ protocol were studied based on such model. The numerical results reveal that the throughput and energy efficiency of the proposed protocol could perform better when compared with the traditional ARQ protocol.
49
Du, Guanyao, Ke Xiong i Zhengding Qiu. "Outage Analysis of Cooperative Transmission with Energy Harvesting Relay: Time Switching versus Power Splitting". Mathematical Problems in Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/598290.
Pełny tekst źródłaStreszczenie:
This paper investigates the multiuser transmission network with an energy harvesting (EH) cooperative relay, where a source transmits independent information to multiple destinations with the help of an energy constrained relay. The relay can harvest energy from the radio frequency (RF) signals transmitted from the source, and it helps the multiuser transmission only by consuming the harvested energy. By adopting the time switching and the power splitting relay receiver architectures, we firstly propose two protocols, the time switching cooperative multiuser transmission (TSCMT) protocol and the power splitting cooperative multiuser transmission (PSCMT) protocol, to enable the simultaneous information processing and EH at the relay for the system. To evaluate the system performance, we theoretically analyze the system outage probability for the two proposed protocols and then derive explicit expressions for each of them, respectively. Numerical results are provided to demonstrate the accuracy of our analytical results and reveal that compared with traditional noncooperative scheme our proposed protocols are green solutions to offer reliable communication and lower system outage probability without consuming additional energy. In particular, for the same transmit power at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain lower system outage probability.
50
Darsena, Donatella, Giacinto Gelli, Ivan Iudice i Francesco Verde. "Separable MSE-Based Design of Two-Way Multiple-Relay Cooperative MIMO 5G Networks". Sensors 20, nr 21 (4.11.2020): 6284. http://dx.doi.org/10.3390/s20216284.
Pełny tekst źródłaStreszczenie:
While the combination of multi-antenna and relaying techniques has been extensively studied for Long Term Evolution Advanced (LTE-A) and Internet of Things (IoT) applications, it is expected to still play an important role in 5th Generation (5G) networks. However, the expected benefits of these technologies cannot be achieved without a proper system design. In this paper, we consider the problem of jointly optimizing terminal precoders/decoders and relay forwarding matrices on the basis of the sum mean square error (MSE) criterion in multiple-input multiple-output (MIMO) two-way relay systems, where two multi-antenna nodes mutually exchange information via multi-antenna amplify-and-forward relays. This problem is nonconvex and a local optimal solution is typically found by using iterative algorithms based on alternating optimization. We show how the constrained minimization of the sum-MSE can be relaxed to obtain two separated subproblems which, under mild conditions, admit a closed-form solution. Compared to iterative approaches, the proposed design is more suited to be integrated in 5G networks, since it is computationally more convenient and its performance exhibits a better scaling in the number of relays.