Improved Bi-Directional Three-Phase Single-Relay Selection Technique for Cooperative Wireless Communications

Abstract

Single-relay selection techniques based on the max-min criterion can achieve the highest bit error rate (BER) performance with full diversity gain as compared to the state-of-the-art single-relay selection techniques. Therefore, in this work, we propose a modified max-min criterion by considering the differences among the close value channels of all relays while selecting the best relay node. The proposed criterion not only enjoys full diversity gain but also offers a significant improvement in the achievable coding gain as compared to the conventional one. Basically, in this article, an improved bi-directional three-phase single-relay selection technique using the decodeand-forward protocol for wireless cooperative communication networks that enhances the overall network performance in terms of BER is proposed and its performance is proved analytically and through Monte-Carlo simulations. More specifically, the proposed criterion is first used to select the best relaynode. After that the selected relay-node forwards the information symbols of the communicating terminals after performing a digital network coding to minimize power consumptions. In our simulations, we show that our proposed technique outperforms the best-known single relay selection techniques. Furthermore, we prove that the BER results obtained from our conducted simulations perfectly match those obtained from the theoretical analysis.

A Beamforming Technique Using Rotman Lens Antenna for Wireless Relay燦etworks

“…In the recent years, several techniques have been proposed in the field of wireless communications to enhance the error performance of the whole system and its achievable throughput [1][2][3][4][5][6]. A group of these techniques works by increasing or optimizing the transmitted power, while another group is applying powerful forward error detection and correction techniques to increase the achievable gain.…”

“…Later on, several schemes are suggested to improve both diversity order and coding gain by combining diversity techniques with coding algorithms including but not limited to space-frequency coding (SFC) schemes and spacetime coding (STC) schemes [10,[13][14][15]. Furthermore, special diversity techniques using beamforming schemes [11][12][17][18][19] are used to steer the transmitting antenna beams towards the destination terminal to enhance the BER performance and the throughput by maximizing the received signal to noise ratio (SNR), given that the BER performance of the multi-antenna systems suffer from the multiuser interference and channel impairments [1][2][3][4][5][6][7][8][9]. In addition, it is very well known that it is difficult to deploy several antennas at the same mobile station due to several limitations.…”

“…In addition, it is very well known that it is difficult to deploy several antennas at the same mobile station due to several limitations. Therefore, cooperative communication systems can be used to overcome this problem by randomly distributing a group of relay nodes between the two communicating parties [5][6][7][8][9][10][11]20,21]. Those relay nodes can be used in two modes of operation, either to amplify and forward (AF) the obtained signals or to detect the transmitted symbols before forwarding them to the receiving antennas.…”

“…However, relaynodes in wireless relay systems process the obtained signals before transmitting them to the destination terminals by merging the obtained copies of the transmitted signal received via several links to enhance the diversity order and coding gain. These schemes are well known as the spatial-diversity schemes [5][6][7][8][9][10][11]. Lately, several improved relaying methods have been introduced to obtain a high diversity and coding gain.…”

NOMA-Based Cooperative Relaying Transmission for the Industrial Internet of Things

“…At present, Multiple-Input-Multiple-Output (MIMO) NOMA system has become a research hotspot [13]. In addition, the cooperative relay technology is more and more recognized by the academic and industrial circles because of its outstanding advantages in increasing the coverage area of wireless cellular mobile networks, improving communication quality, and reducing overall power consumption of network nodes [14][15][16]. The basic idea of cooperative communication is that multiple monitoring equipment cooperate to send their respective information by sharing each other's antennas [17,18], so as to form a virtual array similar to MIMO to combat various channel fading and obtain space diversity gain.…”