신속한 재난경보 방송을 위한 협력통신 기법

In wireless communications, the cooperative communication (CC) technology\npromises performance gains compared to traditional Single-Input Single Output\n(SISO) techniques. Therefore, the CC technique is one of the nominees for 5G\nnetworks. In the Decode-and-Forward (DF) relaying scheme which is one of the CC\ntechniques, determination of the threshold value at the relay has a key role\nfor the system performance and power usage. In this paper, we propose\nprediction of the optimal threshold values for the best relay selection scheme\nin cooperative communications, based on Artificial Neural Networks (ANNs) for\nthe first time in literature. The average link qualities and number of relays\nhave been used as inputs in the prediction of optimal threshold values using\nArtificial Neural Networks (ANNs): Multi-Layer Perceptron (MLP) and Radial\nBasis Function (RBF) networks. The MLP network has better performance from the\nRBF network on the prediction of optimal threshold value when the same number\nof neurons is used at the hidden layer for both networks. Besides, the optimal\nthreshold values obtained using ANNs are verified by the optimal threshold\nvalues obtained numerically using the closed form expression derived for the\nsystem. The results show that the optimal threshold values obtained by ANNs on\nthe best relay selection scheme provide a minimum Bit-Error-Rate (BER) because\nof the reduction of the probability that error propagation may occur. Also, for\nthe same BER performance goal, prediction of optimal threshold values provides\n2dB less power usage, which is great gain in terms of green communicationBER\nperformance goal, prediction of optimal threshold values provides 2dB less\npower usage, which is great gain in terms of green communication.\n

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

In the future, the Internet of things will reduce the cell radius and increase the number of low-power nodes to support thousands of times of traffic growth under 5G. As a virtual multiple input multiple output technology, cooperative communication technology can solve these problems effectively. According to the evolution characteristics of cooperative communication networks, a multi-domain cooperative communication network evolution model with preferential attachment and random attachment is constructed in this article. And then, the network properties and robustness are analyzed using the mean-field method and different attacks. Aiming at the resource constraints and resource allocation problems of communication nodes, a relay selection strategy based on the combination of maximum degree and minimum clustering coefficient is proposed. The simulation results show that the relay node selection strategy based on the combination of maximum degree and minimum clustering coefficient has significant advantages in selection steps and selection time, which greatly enhanced the performance of relay selection in multi-domain cooperative communication networks. Through real-time monitoring and updating of the performance and security indicators of the multi-domain cooperative communication networks, it provides a strong guarantee for the node deployment and security management of the Internet of things cooperative communication system.

In order to cope with the degradation of communication quality due to fading of wireless signals when transmitted over long distances, cooperative communication techniques are often applied to long-distance wireless communications due to their relay cooperative forwarding characteristics. A reasonable relay assignment scheme can significantly improve the network throughput. In order to solve the problem of irrational relay resource assignment in the existing relay assignment under the multi-node cooperative communication network, this paper proposes a relay assignment method that balances the communication quality (BQRA). Firstly, a multi-node cooperative communication system model is established, and a node pre-assignment set is established based on node distance. Then, with the goal of maximizing the overall network capacity, the proposed relay assignment method is used to allocate relay nodes for each source node. The effective performance of the proposed method is evaluated through simulation experiments. Simulation results show that the system channel capacity index is slightly better than several other methods. 15% increase in system channel capacity compared to the classical relay assignment method, LIRA.

This article outlines one way to address these problems by using the notion of cooperation between wireless nodes. In cooperative communications, multiple nodes in a wireless network work together to form a virtual antenna array. Using cooperation, it is possible to exploit the spatial diversity of the traditional MIMO techniques without each node necessarily having multiple antennas. Multihop networks use some form of cooperation by enabling intermediate nodes to forward the message from source to destination. However, cooperative communication techniques described in this article are fundamentally different in that the relaying nodes can forward the information fully or in part. Also the destination receives multiple versions of the message from the source, and one or more relays and combines these to obtain a more reliable estimate of the transmitted signal as well as higher data rates. The main advantages of cooperative communications are presented.

Cooperative networking, by leveraging the broadcast nature of the wireless channel, significantly improves system performance and constitutes a promising technology for next-generation wireless networks. Although there is a large body of literature on cooperative communications, most of the work is limited to theoretical or simulation studies. To impact the next generation of wireless technologies and standards, it is essential to demonstrate that cooperative techniques indeed work in practice. This article describes two programmable cooperative communication testbeds built at Polytechnic Institute of NYU to achieve this goal. The testbeds are based on open-source platforms and enable implementation of cooperative networking protocols in both the physical and the medium access control layer. Extensive experiments carried out using the testbeds suggest not only that cooperative communication techniques can be integrated into current wireless technologies, but also that significant benefits of cooperation can be observed in terms of network throughput, delay, and video quality in real applications.

Cooperative communication is shown to be an efficient method of combating fading in wireless networks. By ”sharing” their antennas cooperating single-antenna nodes create a virtual multi-antenna system and therefore, benefit from spatial diversity. Network coding being a particular cooperative communication technique provides substantial gains in data rate, especially in networks with many sink nodes. By allowing intermediate nodes of a network to mix the incoming data streams, one can achieve the multicast capacity. Recently, Xiao and Skoglund showed that binary network coding (BNC) is not optimal for multi-user multi-relay networks in terms of diversity and proposed diversity network coding (DNC) scheme that outperforms BNC approach. Following this approach we examine potential diversity gains of using the DNC scheme for multi-source line networks. We show that the DNC technique outperforms both conventional time-orthogonal transmission and the BNC scheme. Further, the problem of optimal scheduling of the transmission is explored. We formulate the optimization problem and propose efficient solutions. Numerical results are presented to support theoretical findings.

Energy efficiency and Quality of Service (QoS) have become major requirements in the research and commercial community to develop green communication technologies for cost-effective and seamless convergence of all services (e.g., data, 3D media, Haptics, etc.) over the Internet. In particular, efforts in wireless networks demonstrate that energy saving can be achieved through cooperative communication techniques such as multihop communications or cooperative relaying. Game-theoretic techniques are known to analyze interactions between collaborating entities in which each player can dynamically adopt a strategy that maximizes the number of bits successfully transmitted per unit of energy consumed, contributing to the overall optimization of the network in a distributed fashion. As for the core networks, recent findings claimed that resource over-provisioning is promising since it allows for dynamically booking more resources in advance, and multiple service requests can be admitted in a network without incurring the traditional per-flow signaling, while guaranteeing differentiated QoS. Indeed, heavy control signaling load has recently raised unprecedented concerns due to the related undue processing overhead in terms of energy, CPU and memory consumption. While cooperative communication and resource over-provisioning have been researched for many years, the former focuses on wireless access and the latter on the wired core networks only. Therefore, this chapter investigates existing solutions in these fields and proposes new design approach and guidelines to integrate both access and core technologies in such a way as to provide a scalable and energy-efficient support for end-to-end QoS-enabled communication control. This is of paramount importance to ensure rapid development of attractive 3D media streaming in the current and future Internet.

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).

A CSMA/CA based MAC protocol for hybrid Power-line/Visible-light communication networks: Design and analysis

High power time-varying interference or jamming can severely disrupt wireless communication. Therefore, the technique of relevant interference mitigation is needed. Cooperative communication technique can organize a group of single-antenna systems in the same area at different locations as a distributed antenna array. Thus it can approximately achieve the diversity gain of regular multiple-antenna system. This paper is focused on cooperative communication for time-varying interference mitigation. Since some of traditional collaborative reception techniques have the constraint of requiring accurate estimation of SNR, an improvement of time-varying interference mitigation technique based on log-likelihood ratio (LLR) and jammer cancellation is proposed. The simulation results demonstrate that this new improved method enables communication in much more severe interference conditions.

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.

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.

New technologies and communication standards have changed traditional network processes. Internet of Things (IoT) is one of the emerging technologies where devices are connected to facilitate the users. When the networks are more congested due to a large number of users then the existing routing protocol and communication channels suffer from congestion, disconnection, overhead, and packet drop issues. Unmanned Aerial Vehicles (UAVs) are adopted to support the ground networks for more feasible data communication. These networks provide coverage facilities to IoT networks and provide smooth data dissemination services. Through the use of relay and cooperative communication technologies, UAVs could enlarge the communication space for IoT networks. Traditional network routing protocols have been adopted for data communication in these networks. However, the adopted protocols are not able to handle mobility and uncertain network conditions. This paper proposes a Decision-based Routing for Unmanned Aerial Vehicles and Internet of Things (DR-UAVIoT) network. The proposed protocol is useful for UAV-to-IoT and UAV-to-UAV data communication. The performance of the proposed solution is evaluated with the existing protocols in terms of data delivery, delay, and network overhead. The experimental results indicate the better performance of the proposed protocol in terms of less delay, less overhead, and better data delivery ratio as compared with existing routing protocols.

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.