BICM-Based Cooperative Communication Systems with Relay Selection: Constellation and Multiplexer Design

2014 ◽  
Author(s):  
Muhammad Talha Malik ◽  
Md. Jahangir Hossain ◽  
Mohamed-Slim Alouini
Keyword(s):  
Cooperative Communication ◽  
Communication Systems ◽  
Relay Selection

scholarly journals Analyzing bit error rate of relay sensors selection in wireless cooperative communication systems

2021 ◽  
Vol 10 (1) ◽  
pp. 216-223
Author(s):  
Ahmed Allawy Alawady ◽  
Ahmed Alkhayyat ◽  
Mohammed Ahmed Jubair ◽  
Mustafa Hamid Hassan ◽  
Salama A. Mostafa
Keyword(s):  
Cooperative Communication ◽  
System Performance ◽  
Communication Systems ◽  
Relay Selection ◽  
Relay Node ◽  
Cooperative Systems ◽  
Diversity Order ◽  
Channel Fading ◽  
Negative Effects ◽  
Relay Nodes

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.

Relay Selection Scheme for Cooperative Communication Systems in Fixed Decode-and-Forward Mode

2014 ◽  
Vol 6 (2) ◽  
pp. 68-77
Author(s):  
Jyh-Horng Wen ◽  
Jheng-Sian Li ◽  
Hsiang-Shan Hou ◽  
Cheng-Ying Yang
Keyword(s):  
Cooperative Communication ◽  
System Performance ◽  
Communication Systems ◽  
Relay Selection ◽  
Spatial Diversity ◽  
Search Method ◽  
Exhaustive Search ◽  
Decode And Forward ◽  
Selection Scheme ◽  
Relay Stations

Cooperative system is a tendency in the future communications because it provides a spatial diversity to improve the system performance. This work considers the cooperative communication systems in Fixed DF Mode. The scenario includes multiple source stations, multiple relay stations and multiple destination stations. For the whole system, the maximum throughput approaching is the major purpose. Hence, to select the relay stations for signal transmission could be the important scheme to achieve the optimal system performance. With the exhaustive search method, easily to realize, the optimal selection scheme could be found with a highly complicated calculation. In order to reduce the computational complexity, a relay selection scheme is proposed. With different situations of the communication systems, the performances evaluations obtained with both the proposed algorithm and the exhaustive search method are given for comparison. It shows the proposed algorithm could provide a solution approaches to the optimal one. It could apply the proposed scheme to the practical without a delay because of long-time calculation.

scholarly journals A Novel Relay Selection Scheme Based on Q-Learning in Multi-Hop Wireless Networks

2020 ◽  
Vol 10 (15) ◽  
pp. 5252
Author(s):  
Min-Jae Paek ◽  
Yu-Jin Na ◽  
Won-Seok Lee ◽  
Jae-Hyun Ro ◽  
Hyoung-Kyu Song
Keyword(s):  
Wireless Networks ◽  
Cooperative Communication ◽  
Optimal Policy ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Relay Selection ◽  
Large Scale ◽  
Base Station ◽  
Selection Scheme ◽  
Q Learning

In wireless communication systems, reliability, low latency and power are essential in large scale multi-hop environment. Multi-hop based cooperative communication is an efficient way to achieve goals of wireless networks. This paper proposes a relay selection scheme for reliable transmission by selecting an optimal relay. The proposed scheme uses a signal-to-noise ratio (SNR) based Q-learning relay selection scheme to select an optimal relay in multi-hop transmission. Q-learning consists of an agent, environment, state, action and reward. When the learning is converged, the agent learns the optimal policy which is a rule of the actions that maximize the reward. In other words, the base station (BS) knows the optimal relay to select and transmit the signal. At this time, the cooperative communication scheme used in this paper is a decode-and-forward (DF) scheme in orthogonal frequency division multiplexing (OFDM) system. The Q-learning in the proposed scheme defines an environment to maximize a reward which is defined as SNR. After the learning process, the proposed scheme finds an optimal policy. Furthermore, this paper defines a reward which is based on the SNR. The simulation results show that the proposed scheme has the same bit error rate (BER) performance as the conventional relay selection scheme. However, this paper proposes an advantage of selecting fewer relays than conventional scheme when the target BER is satisfied. This can reduce the latency and the waste of resources. Therefore, the performance of the multi-hop transmission in wireless networks is enhanced.

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