Cooperative Communication Techniques Research Articles

Improving Performance of the Typical User in the Indoor Cooperative NOMA Millimeter Wave Networks with Presence of Walls

INTRODUCTION: The beyond 5G millimeter wave cellular network system is expecting to provide the high quality of service in indoor areas. OBJECTIVES: Due to the high density of obstacles, the cooperative communication technique is employed to improve the user's desired signal power by finding more than one appropriate station to serve that user. METHODS: While the conventional system utilizes additional equipment such as Reconfigurable Intelligent Surfaces (RIS) and relays to enable the cooperative features, the paper introduces a new network paradigm that utilizes the second nearest Base Station (BS) of the typical user as the Decode and Forward (DF) relay. Thus, depends on the success of decoding the message from the user' serving BS of the second nearest BS, the typical user can work with and without assistance from the relay whose operation follows the discipline of the power-domain NOMA technique. In the case of with relay assistance, the Maximum Ratio Combining technique is utilized by the typical user to combine the desired signals. RESULTS: To examine the performance of the proposed system, the Nakagami-m and the newly developed path loss model, which considers the density of walls and their properties, are adopted to derive the coverage probability of the user with and without relay assistance. The closed-form expressions of this performance metric are derived by Gauss quadrature and Welch-Satterthwaite approximation.

Maximizing Average Throughput of Cooperative Cognitive Radio Networks Based on Energy Harvesting.

Energy harvesting (EH) and cooperative communication techniques have been widely used in cognitive radio networks. However, most studies on throughput in energy-harvesting cooperative cognitive radio networks (EH-CCRNs) are end-to-end, which ignores the overall working state of the network. For the above problems, under the premise of prioritizing the communication quality of short-range users, this paper focuses on the optimization of the EH-CCRN average throughput, with energy and transmission power as constraints. The formulated problem was an unsolved non-deterministic polynomial-time hardness (NP-hard) problem. To make it tractable to solve, a multi-user time-power resource allocation algorithm (M-TPRA) is proposed, which is based on sub-gradient descent and unary linear optimization methods. Simulation results show that the M-TPRA algorithm can improve the average throughput of the network. In addition, the energy consumed by executing the M-TPRA algorithm is analyzed.

Performance Analysis of Cooperative Multiple Access With Minimum Interference Range for Large Scale Wireless Networks

Cooperative communication techniques are widely used in large-scale wireless networks for improving network throughput. This is achieved through the creation of transmission diversity by forming multiple cooperative transmission links which involve several relaying nodes as helpers for an end-to-end data transmission. Consequently, link interference range will inevitably be enlarged, which will adversely hamper the diversity created and offset the network throughput improvement as a result. This problem has not been properly addressed by most cooperative communication protocols reported so far. In this paper, a novel protocol that performs cooperative medium access control as well as minimizes the interference range, namely MIR-CMAC, is proposed to directly address the enlarged link interference range problem introduced by cooperative communication. Specifically, functions like channel reservation, cooperative priority differentiation and contention for relay selection are collectively enabled in MIR-CMAC to reduce channel access collision and select the suitable helper node that can maximize the integrated link data rate and minimize the link interference concerned. In addition, a full interference model is established to evaluate the effect of interference across the whole process from channel access to packet transmission and derive a new network throughput analysis method for MIR-CMAC. Both numerical and simulation results demonstrate the effectiveness of MIR-CMAC and its performance improvements over other protocols.

A sleep scheduling based cooperative data transmission for wireless sensor network

ABSTRACT Wireless sensor network is the network of tiny size of sensor nodes. These sensor nodes have sensing capability and transmit the sensed information to sink node. If the energy of sensor nodes is not utilised properly, it results in performance degradation of the network. Sleep scheduling approach and cooperative communication techniques can be employed to enhance the network performance. Cooperative communication follows the relay-based transmission. The nodes turn its radio sleep and awake in sleep scheduling approaches. This paper considers the merits of both techniques and proposes the sleep scheduling-based cooperative data transmission approach for WSN. In this approach, optimal number of virtual cluster heads are calculated by the sink node according to the number of nodes and area of interest. The real cluster head is decided based on the distance and energy of the sensor nodes from the virtual cluster head. The node is paired with each other and follows the sleep scheduling approach. Further, the energy-efficient relay selection and data transmission according to cooperative technique improves the network performance. The simulation analysis shows that the proposed routing protocol outperforms the related existing routing protocols.

Predictors of Entrepreneurial Intention of Nursing Students Based on Theory of Planned Behavior.

PurposeThe theory of planned behavior has previously been applied as a theoretical framework for improving entrepreneurial intention in nurses. Our study aimed to draw major variables from these studies and establish a structural equation model that defines predictors explaining nursing entrepreneurial intention.Participants and MethodsParticipants included 252 nursing students from four nursing colleges in urban cities of South Korea. The structural equation model was constructed using six variables. Entrepreneurial-personal attitude, entrepreneurial-subjective norm, and entrepreneurial-perceived behavioral control from the theory of planned behavior model were used as exogenous variables, and entrepreneurial education demand, entrepreneurial self-efficacy, and entrepreneurial intention were used as endogenous variables. The data were analyzed using the SAS and LISREL programs.ResultsEntrepreneurial perceived behavioral control, entrepreneurial education demand, and entrepreneurial self-efficacy directly affected entrepreneurial intention, whereas entrepreneurial personal attitude and entrepreneurial subjective norm had indirect effects. The explanatory power of the modified model for entrepreneurial intention was 76.0%. These results suggested that expanding entrepreneurial education opportunities and developing interventions for enhancing entrepreneurial self-efficacy are necessary to improve entrepreneurial intention in nursing students.ConclusionThe results of this study will be used as basic data for developing curriculums and intervention programs to increase entrepreneurial intention in nursing students. To do this, we suggest that new pedagogies involving entrepreneurial project-based classes, business idea contests, and research and technology are useful tools to facilitate the next step of practical entrepreneurial preparation. Furthermore, an entrepreneurship-oriented culture needs to be fostered and include entrepreneur mentoring, team building, cooperative communication techniques, funding support, and a college-level support system.

An Efficient Cooperative Routing Algorithm for Large-Scale Wireless Networks based on Capacity and Location

Cooperative communication has been extensively used in small-scale wireless networks, by virtue of its capability to mitigate the fading effects. Extending cooperative communication technique to large-scale networks undergoes severe interference; multi-radio-multi-channel is exploited in large scale wireless networks to ameliorate throughput by concurrent transmissions over orthogonal channels to dwindle interference. Capitalising on these potential advantages, stand in need for efficacious routing and potent mapping of channels to radios. In this paper, we have proffered an algorithm by concurrently considering: 1) relay selection using distance and maximum-available-channel-capacity parameters; 2) channel assignment using dynamic global table. Our algorithm selects a relay-node based on the available channel capacity in the shortest-path to minimise the transmission delay without affecting aggregate throughput. The evaluation and analysis of the proposed model is compared with interference-aware-cooperative-routing algorithm and observed that the proposed algorithm has improved delay reduction by 27.5% and the average number of hops by 32.5%.

Energy efficient resource optimization in cooperative Internet of Things networks

Internet of Things (IoT) network has been envisioned as a promising technology to satisfy the exponentially growing mobile traffic requirements. Cooperative communication technique has been proposed to significantly improve energy efficiency in resource-constrained network. In this paper, we focus on resource allocation optimization and optimal relay selection to maximize the energy efficiency of the IoT networks. Using different cooperative techniques, we have studied the resource optimization problems for a single-hop network topology and a generic cooperative multi-hop network topology. Based on dual optimization framework, we formulate an optimal algorithm to reduce the total transmit power through channel allocations and optimal relay selection for each source to destination communication link while satisfying the quality of service (QoS) requirements. We derive the closed-form expressions for the outage probabilities of the cooperative relaying protocols to improve data transmission and propose an energy efficient power routing algorithm to enhance energy efficiency. Simulation results show an effective performance gain of the proposed algorithm as compared with other existing power saving algorithms in terms of system throughput and energy efficiency.

Geographic information-based Data Transmission and Cooperative Communication for Vehicular Networks

With the advancements in Vehicular communication technologies in automobile engineering leads to enhancement of modern societies by utilizing Internet based data communication in a vehicular network to effectively avoid accidents and traffic congestions using Multi Input Multi Output (MIMO) cooperative relay technique for enhancing the aspects of performance by reduction of transmission energy consumption by taking the advantage of spatial and temporal diversity gain in a vehicular network as the conventional routing based on topology is merely not suitable over a dynamic vehicular network environment as GPS is used to identify effective route [4].In this paper we propose applications of cooperative communication techniques and their survey for identifying close relationship between forwarding and addressing techniques in a vehicular network and further we compare performance and energy consumption of cooperative techniques with the traditional multi-hop technique over Rayleigh channel using MQAM for optimization.

Geographic information-based Data Transmission and Cooperative Communication for Vehicular Networks

With the advancements in Vehicular communication technologies in automobile engineering leads to enhancement of modern societies by utilizing Internet based data communication in a vehicular network to effectively avoid accidents and traffic congestions using Multi Input Multi Output (MIMO) cooperative relay technique for enhancing the aspects of performance by reduction of transmission energy consumption by taking the advantage of spatial and temporal diversity gain in a vehicular network as the conventional routing based on topology is merely not suitable over a dynamic vehicular network environment as GPS is used to identify effective route [4].In this paper we propose applications of cooperative communication techniques and their survey for identifying close relationship between forwarding and addressing techniques in a vehicular network and further we compare performance and energy consumption of cooperative techniques with the traditional multi-hop technique over Rayleigh channel using MQAM for optimization.

Advanced Dynamic Spectrum 5G Mobile Networks Employing Licensed Shared Access

Spectrum sharing has been recognized as a key component for 5G and beyond wireless networks. Recent trials have revealed the business value of spectrum sharing via the licensed shared access model, wherein both the incumbent and the licensee operators are protected from harmful interference by sharing the available spectrum using long-term spectrum access agreements. Further increase in capacity gains can be achieved by exploiting dynamic spectrum access, where access is granted in shorter time intervals, and the Spectrum Access System, which is a more flexible version of traditional LSA. This article first hints at LSA-type spectrum sharing in regulatory and standards bodies, then proposes a few relevant scenarios that would take advantage of LSA, and finally presents an LSA system architecture and some enabling technologies for LSA/DSA/SAS. These include novel sensing, dynamic and radioaware resource allocation, and advanced cooperative communication techniques.

A Survey of Device to Device and Cooperative Communication for the Future Cellular Networks

Device to Device and Cooperative communication are the two new emerging technologies in the new era of communication technology which differ from the existing cellular technology. In review article we have enlisted different technologies which play a very important role in third Generation Partnership Project (3GPP). In this paper we have studied the various techniques of resource allocation, Mode selection for underlay communications in terms of device to device and cooperative communication techniques in terms of Long Term Evolution and Long Term Evolution-Advanced platform. A new technique LTE-Advanced Pro has also been introduced by 3GPP. Various simulators including Vienna LTE-Advanced have also been discussed. Better utilization of the spectrum is also depicts which is done on the basis of analysis if proper resource allocation whether it is power, frequency or time and mode selection is done in the programmed manner which would result in the reduction of interference and it will also lead to the secure system.

Cooperative Communication and Energy-Harvesting-Enabled Energy-Efficient Design of MI-Based Clustered Nonconventional WSNs

The communication based on electromagnetic waves in nonconventional media (underground and underwater environment) is not desirable because of high path loss, large antenna size, and dynamic channel behavior of the media. Magnetic induction (MI) based communication is recently explored technique for such type of media, which exhibits several promising characteristics, such as constant channel behavior, less propagation delay, and stealth underwater operations. In every wireless sensor network (WSNs), energy is a main constraint. The overall energy consumption of the network can be significantly reduced by clustering technique. The efficacy of clustering technique can be further improved by the incorporation of cooperative communication and energy harvesting (EH) techniques. This paper proposes cooperative communication over Rayleigh fading channels, EH-enabled energy-efficient design, and EH-enabled tree-based waveguide topology in MI-based clustered nonconventional WSNs. Furthermore, we perform an analytical modeling to find the total energy consumption and throughput of the network in three different media (dry soil, wet soil, and sea water).

An Optimized Relay Selection Technique to Improve the Communication Reliability in Wireless Sensor Networks.

Wireless Sensor Networks (WSN) are enabler technologies for the implementation of the Internet of Things (IoT) concept. WSNs provide an adequate infrastructure for the last-link communication with smart objects. Nevertheless, the wireless communication medium being inherently unreliable, there is the need to increase its communication reliability. Techniques based on the use of cooperative communication concepts are one of the ways to achieve this target. Within cooperative communication techniques, nodes selected as relays transmit not only their own data, but also cooperate by retransmitting data from other nodes. A fundamental step to improve the communication reliability of WSNs is related to the use of efficient relay selection techniques. This paper proposes a relay selection technique based on multiple criteria to select the smallest number of relay nodes and, at the same time, to ensure an adequate operation of the network. Additionally, two relay updating schemes are also investigated, defining periodic and adaptive updating policies. The simulation results show that both proposed schemes, named Periodic Relay Selection and Adaptive Relay Selection, significantly improve the communication reliability of the network, when compared to other state-of-the-art relay selection schemes.

Cooperative communication system with multiple relays for performance improvement in wireless communication system

In a wireless communication system, a cooperative communication technique is a communication method for improving performance. In the conventional scheme, when a destination user is located in the cell boundary, one base station communicates with a destination user. At a same time, a destination user communicates with other base stations which cooperate with base station. If a distance between a base station and a destination user is far, the quality of communication is degraded by the effect of channel attenuation. Therefore, this paper proposes an enhanced cooperative transmission scheme using the orthogonal frequency multiplexing in the wireless communication system. The proposed scheme uses extra relays between a base station and a destination user. When the channel state of a destination user is bad, other base stations are used. In order to obtain better performance than the conventional scheme, the cooperative decode and forward (DF), and space time cyclic delay diversity (STCDD) and cyclic delay diversity (CDD) are applied in the extra relays. In simulation results, the proposed scheme has higher error and throughput performances than the conventional scheme for obtaining diversity gain when the used modulation scheme is increased. Also, the proposed scheme which uses cooperative DF has slightly better error and throughput performances than the proposed scheme which uses cooperative STCDD and CDD due to less error propagations and resultant higher diversity gain.

A Fair Cooperative MAC Protocol in IEEE 802.11 WLAN

Cooperative communication techniques have recently enabled wireless technologies to overcome their challenges. The main objective of these techniques is to improve resource allocation. In this paper, we propose a new protocol in medium access control (MAC) of the IEEE 802.11 standard. In our new protocol, which is called Fair Cooperative MAC (FC-MAC), every relay node participates in cooperation proportionally to its provided cooperation gain. This technique improves network resource allocation by exploiting the potential capacity of all relay candidates. Simulation results demonstrate that the FC-MAC protocol presents better performance in terms of throughput, fairness, and network lifetime.

Energy efficiency of cooperative D2D communications underlaying LTE-A networks

Device-to-device (D2D) communications underlaying LTE-A networks is expected to bring significant benefits for resource utilization and energy efficiency (EE) improvement of user equipment (UE). However, the allocation of radio and power resources to D2D communications needs elaborate coordination, because of the interference between D2D communications and cellular communications. In this paper, we propose an energy-efficient cooperative D2D communication (EECD2D) technique using a power allocation algorithm, aiming at maximizing EE introduced by D2D communications in LET-A networks. Specifically, we define four D2D and cellular combinations based on distances, and analyze average EE of EECD2D and that of cooperative D2D communications without optimization. Results show that average EE of our algorithm is much higher than that without optimization, and closer D2D cooperators and distant cellular UEs whose uplink resource is reused, achieve highest average energy efficiency.

A new cooperative communication algorithm for improving connectivity in the event of network failure in VANETs

Communication in Vehicular Ad-Hoc Networks (VANETs) is frequently disrupted by high mobility of nodes, obstacles, and interference-prone links. The communication link between nodes can be maintained using cooperative communication techniques where nodes collaborate with one another to increase the network performance. Implementation of cooperative communication, which requires helpful nodes to collaborate with others, is a difficult task in VANETs due to their inherent characteristics. Selection of a cooperative node which will help during the retransmission process is the most crucial work in the cooperative communication process considering the dynamic nature of nodes. In this study, we formulate a game-theoretic relay selection protocol for MAC-level retransmission, where every node plans to maximize their received incentives, which is determined by an incentive function. Therefore, cooperative neighboring nodes form tree structures to the destination node from transmitter node by using the proposed algorithm, NGOMA. The distributed incentive function stores promiscuous packets in nodes and forms a tree architecture with cooperative nodes to relay messages to the recipient node from the source node in times of packet-loss events. The network formed by the NGOMA protocol by the source and destination node with relay nodes, converges into a Nash network. Numerical results show that NGOMA, which allows nodes to cooperatively store and transmit lost packets to the recipients, reduces the MAC-level retransmission delay by 63% compared to a non-cooperative function, which does not cooperatively relay messages.

Time Reversal Aided Bidirectional OFDM Underwater Cooperative Communication Algorithm with the Same Frequency Transmission

In underwater acoustic channel, signal transmission may experience significant latency and attenuation that would degrade the performance of underwater communication. The cooperative communication technique can solve it but the spectrum efficiency is lower than traditional underwater communication. So we proposed a time reversal aided bidirectional OFDM underwater cooperative communication algorithm. The algorithm allows all underwater sensor nodes to share the same uplink and downlink frequency simultaneously to improve the spectrum efficiency. Since the same frequency transmission would produce larger intersymbol interference, we adopted the time reversal method to degrade the multipath interference at first; then we utilized the self-information cancelation module to remove the self-signal of OFDM block because it is known for sensor nodes. In the simulation part, we compare our proposed algorithm with the existing underwater cooperative transmission algorithms in respect of bit error ratio, transmission rate, and computation. The results show that our proposed algorithm has double spectrum efficiency under the same bit error ratio and has the higher transmission rate than the other underwater communication methods.

CARCC: Connectivity Autorecovering via Cooperative Communication

Wireless ad hoc networks are often considered an alternative for providing communication means to support urgent and temporary tasks. In such settings, network connectivity is a primary condition to allow nodes to exchange information. In this work we explore the use of cooperative communication (CC) techniques for improving network connectivity. The proposed solution, named Connectivity Autorecovering with Cooperative Communication (CARCC), monitors potential network disruption points and proactively creates cooperative links (CC-links). These links are used to regain network connectivity when necessary. CARCC allows the selection of suitable CC-links in O(Δ(G)×Λ) time, whereas a centralized approach takes O(V2×Λ) time, where Δ(G) is the degree of the underline network graph G(V,E) and Λ is the computational cost of selecting helper nodes. Although CARCC relies on localized information, it is able to provide comparable results of other noteworthy alternatives that require global topological information. The CC-links provided by CARCC reestablished network connectivity in over 91% in the evaluated settings.

AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative Routing in Ad Hoc Networks

The cooperative communication technique in an ad hoc network exploits the spatial diversity gains inherent in multiuser systems and mitigates the multipath fading. This technique is necessary but perhaps not sufficient to meet the QoS demands in ad hoc network. This is due to the fact that routing protocol at the network layer is more responsible for the successful packet delivery and QoS support. In this paper, we propose an adaptive multi-QoS cross-layer cooperative routing (AMCCR) protocol that enhances the performance through the cooperation of physical, MAC, and network layers. We first formulate an approach to analyze the channel state variations for effective communication schemes at the physical layer. Secondly, we dynamically select the transmission mode to employ cooperative MAC scheme by exploiting spatial diversity. Thereafter, the network layer chooses an optimized route from source to destination through the selected best relay candidates based on multiple QoS metrics. The paper is further extended to support dual-hop half-duplex communication via selected relay by coding technique. The proposed protocol is validated by extensive simulations and compared with CD-MAC and CODE protocols. The results clearly show that the proposed cooperative cross-layer design approach significantly improves the average delay, throughput, and network lifetime of the system.