Cooperative Communication Scheme Research Articles

Cooperative communication system for high performance using ambient signals

This paper proposes the Internet connectivity of RF-powered devices in the backscatter system. The RF-powered devices do not use a battery and charge energy by harvesting from ambient RF signals of TV, a cellular phone and Wi-Fi devices. The Internet connectivity of the RF-powered devices in the backscatter system is very useful in Internet of things technology because the RF-powered devices which are called to a tag have a small size by the harvesting from ambient RF signals without a battery. This paper proposes a method improving the communication performance of the Wi-Fi backscatter system by applying the cooperative communication scheme.

Coordinated Multiple-Relays Based Physical-Layer Security Improvement: A Single-Leader Multiple-Followers Stackelberg Game Scheme

In this paper, a coordinated multiple-relays-based cooperative communication scheme is proposed to improve the physical-layer security. In order to benefit the relays in forwarding the signals for defending against the eavesdropping attacks, the interactions between the source and the multiple relays are modeled as a single-leader multiple-followers Stackelberg game. The source plays as the leader to coordinate the relays, including the phase of signals forwarded by the relays and the transmit power of the relays, for maximizing the secrecy capacity of the system. An algorithm is developed for the relays to find an optimal price allocation to achieve the fairness among the multiple relays based on the egalitarian welfare solution, and an approximate optimal strategy of source (i.e., phase coordinated vector and power allocation) is studied. The closed-form intercept probability of the proposed scheme is derived. Numerical studies demonstrate that the proposed scheme can greatly improve the utilities of both the source and multiple relays over that resulted from the Nash equilibrium scheme and rand scheme, which means that the relays are more willing to participate in the cooperative communication, and the source can achieve better secure transmission based on the proposed scheme. It is also shown that the proposed scheme performs much better in defending against the eavesdropping attacks than those existing schemes, for example, the single relay selection scheme, the opportunistic relay selection scheme, the optimal relay scheme, and cooperative jamming scheme.

Secure cooperative communication scheme for vehicular heterogeneous networks

Vehicular Heterogeneous Network (VHN) is a massive network which contains dedicated short range communication (DSRC) based on IEEE 802.11p, Device-to-Device (D2D) communication and cellular network (e.g., 5G). VHN is supposed to complete the interactions of V2X (where X stands for vehicle, road, pedestrian and Internet) and cooperative communications among multiple networks. However, different networks use different communication protocols so that it is hard to implement cooperative communication. Furthermore, due to the openness of wireless channels, communication links are vulnerable to eavesdroppers and cannot guarantee the confidentiality. To deal with these problems, this paper designs an On Board Unit (OBU) with multi-level security. Meanwhile, we implement cooperative communication using designed OBU, for which OBU performs the vertical handoff and selects best mode with consideration of communication requirements. In VHN, we also consider a network model which contains an eavesdropper, and present formulations to describe its specific security problem by utilizing stochastic geometry theory. Thereafter, we propose a secure cooperative communication scheme which uses physical layer security, and explore secrecy-based successful transmission probability as well as transmission capacity. In addition, we propose mode selection and optimization algorithms to improve security of the proposed cooperative communication. Finally, experimental results show that our proposed scheme is feasible and achieves better security than other communication schemes in comparison.

AN-Aided Relay-Selection Scheme for Securing Untrusted RF-EH Relay Systems

Energy harvesting (EH) technology has imposed new constraints on the amount of time an energy-constrained relay node needs to use for EH and information forwarding. Moreover, EH techniques may increase vulnerability to eavesdropping, since a power receiver, as a potential eavesdropper, usually has a shorter access distance than an information receiver. Motivated by this issue, in this paper, we investigate a tradeoff between energy consumption and physical layer security in a wireless powered-untrusted cooperative communication (WPUCC) network consisting of one source-destination pair and multiple amplify-and-forward untrusted relays. To minimize the energy consumption of the network, we propose a secure adaptive relay-based cooperation approach. Moreover, a greedy battery-aware relay-selection scheme is proposed to minimize the power consumption in WPUCC systems. Using power-splitting-based energy accumulation, untrusted relays attempt to intercept the information intended to the legitimate destination while harvesting energy at the same time. To keep the information secure from potential eavesdropping, the source injects a jamming signal along with its data signal. By modeling the dynamic behavior of the relay battery as a finite-state Markov chain, we derive an analytical expression for the secrecy outage probability of our proposed secure adaptive harvest-use-store cooperative communication scheme and show that it is more secure than its direct transmission and pure two-hop transmission counterparts.

A Cooperative Communication Model Tailored for Energy Balance in Wireless Sensor Networks

Wireless Sensor Networks (WSN) are characterized by their capacity of monitoring the environment, gathering and sharing information. Nodes in a WSN usually cooperate in the task of forwarding the sensed data to a sink node for later retrieval and analysis. The success of this task depends on the availability of efficient routes that meet the application requirements. As topology may change overtime, alternatives to improve and maintain network connectivity are highly desired. In this context, Cooperative Communication (CC) emerged as an alternative to improve network connectivity. Despite its benefits, CC-links are known to have higher energy demands as compared to traditional, direct, links. In particular, CC-links require the source node to expend more power than others nodes, shortening their life span. The main contribution of this paper is to propose a new Cooperative Communication model, capable of increasing the energy balance of the CC-links while improving network connectivity. Simulation results show that, compared to other CC schemes, the source node of a Cooperative Communication reduces the amount of expended energy by 68% in the evaluated settings.

Secure Communication in OFDMA-Based Cognitive Radio Networks: An Incentivized Secondary Network Coexistence Approach

In this paper, we propose a secure cooperative communications scheme for orthogonal frequency-division multiple-access (OFDMA) cognitive radio networks (CRNs), where a primary base station (PBS) wants to transmit information to some distant primary users (PUs) in the presence of a set of passive eavesdroppers. In our model, the transmission is performed in two consecutive time slots; in the first time slot, the PBS transmits while the secondary users (SUs) and the eavesdroppers listen. In the second time slot, the SUs transmit while the PUs, the secondary base station (SBS), and the eavesdroppers listen. We consider two schemes for eavesdropping; in the first scheme, the eavesdroppers listen to transmissions from the PBS to the SUs, and in the second scheme, we assume that the eavesdroppers apply the maximal ratio combining approach on the received signals in the first and second time slots for the primary network. In the proposed model, the SUs are allowed to use the licensed spectrum of the PUs, as long as they help the PUs to satisfy their secrecy rate requirement. We assume a frame-based transmission where each frame is divided into two consecutive time slots of equal duration. In the first time slot, the PBS transmits while the SUs and the eavesdroppers listen. In the second time slot, the selected SUs relay the PBS information to the distant PUs. Meanwhile, the SUs use the remaining resources to transmit their own information to the SBS while the eavesdroppers listen to this transmission. We formulate our proposed schemes as an optimization problem and solve it by dual Lagrange approach. We evaluate our proposed scheme in various situations using simulations and show the efficiency of the proposed scheme. An important aspect of the proposed paradigm is that replacing the conventional average interference threshold constraint by the primary secrecy rate constraint does not only decrease the secondary average secrecy rate with respect to the conventional case but can actually provide significantly higher secondary average secrecy rate as well.

Throughput of Infrastructure-Based Cooperative Vehicular Networks

In this paper, we provide detailed analysis of the achievable throughput of infrastructure-based vehicular network with a finite traffic density under a cooperative communication strategy, which explores combined use of vehicle-to-infrastructure (V2I) communications, vehicle-to-vehicle (V2V) communications, mobility of vehicles and cooperations among vehicles and infrastructure to facilitate the data transmission. A closed form expression of the achievable throughput is obtained, which reveals the relationship between the achievable throughput and its major performance-impacting parameters such as distance between adjacent infrastructure points, radio ranges of infrastructure and vehicles, transmission rates of V2I and V2V communications and vehicular density. Numerical and simulation results show that the proposed cooperative communication strategy significantly increases the throughput of vehicular networks, compared with its non-cooperative counterpart, even when the traffic density is low. Our results shed insight on the optimum deployment of vehicular network infrastructure and optimum design of cooperative communication strategies in vehicular networks to maximize the throughput.

Cooperative Topology Control for Low Interference in Wireless Ad Hoc Networks

Cooperative communication (CC) can exploit spatial diversity via neighbour's antennas, which may cause serious interference as well. However, previous works rarely consider guaranteeing the interference performance in the cooperative topology control problem for wireless ad hoc networks. In this paper, we first introduce a nodal interference model for the CC scheme. Based on this model, we formalise two critical problems: CTC-MMI which aims to obtain a strongly connected topology with min-max interference, and CTC-MAI which aims to construct a strongly connected topology with min-average interference. Then, we design DBS to solve CTC-MMI optimally. We also propose a distributed algorithm DBCT for CTC-MAI and prove that DBCT can reach the approximate factor of 4. Finally, extensive simulations show that the high efficiency of the proposed algorithms. For example, DBCT can construct the cooperative topology with low-average interference, and reduce the energy consumption by about 30% compared with traditional methods.

Cooperative topology control for low interference in wireless ad hoc networks

Cooperative communication (CC) can exploit spatial diversity via neighbour's antennas, which may cause serious interference as well. However, previous works rarely consider guaranteeing the interference performance in the cooperative topology control problem for wireless ad hoc networks. In this paper, we first introduce a nodal interference model for the CC scheme. Based on this model, we formalise two critical problems: CTC-MMI which aims to obtain a strongly connected topology with min-max interference, and CTC-MAI which aims to construct a strongly connected topology with min-average interference. Then, we design DBS to solve CTC-MMI optimally. We also propose a distributed algorithm DBCT for CTC-MAI and prove that DBCT can reach the approximate factor of 4. Finally, extensive simulations show that the high efficiency of the proposed algorithms. For example, DBCT can construct the cooperative topology with low-average interference, and reduce the energy consumption by about 30% compared with traditional methods.

Secure beamforming design for SWIPT in cooperative D2D communications

In device-to-device (D2D) communications, device terminal relaying makes it possible for devices in a network to function as transmission relays for each other to enhance the spectral efficiency. In this paper we consider a cooperative D2D communication system with simultaneous wireless information and power transfer (SWIPT). The cooperative D2D communication scheme allows two nearby devices to communicate with each other in the licensed cellular bandwidth by assigning D2D transmitters as half-duplex (HD) relay to assists cellular downlink transmissions. In particular, we focus on secure information transmission for the cellular users when the idle D2D users are the potential eavesdroppers. We aim to design secure beamforming schemes to maximize the D2D users data rate while guaranteeing the secrecy rate requirements of the cellular users and the minimum required amounts of power transferred to the idle D2D users. To solve this non-convex problem, a semi-definite programming relaxation (SDR) approach is adopted to obtain the optimal solution. Furthermore, we propose two suboptimal secure beamforming schemes with low computational complexity for providing secure communication and efficient energy transfer. Simulation results demonstrate the superiority of our proposed scheme.

Maximizing Quality of Experience in Device-to-Device Communication Using an Evolutionary Algorithm Based on Users’ Behavior

End users’ quality of experience (QoE) is one of the most crucial requirements to be considered in device-to-device communication. Users’ QoE is affected by the ratio of the amount of received data to the amount of shared data. The ratio should be approximate to 1. To achieve this, we propose an evolutionary algorithm-based cooperative content caching and communication (EACCC) scheme. This scheme works by finding the maximum 1-factor of a directed weighted graph, where each edge’s weight corresponds to the mean opinion score of the connection between two users. Finding the maximum 1-factor of graph-based communication is a problem that is difficult to solve optimally, but an evolutionary algorithm can quickly converge to a high-quality solution. Each user provides an opinion score of incoming and outgoing connection, and the maximum 1-factor corresponds to the scheme that maximizes overall QoE. The proposed EACCC scheme achieves optimal connections among users in a vast and complex network, due to strong mutual communication. The simulation results verify that our proposed scheme outperforms traditional QoE optimization schemes. Moreover, our scheme can be implemented easily in a realistic scenario.

LTE-Railway User Priority-Based Cooperative Resource Allocation Schemes for Coexisting Public Safety and Railway Networks

This paper addresses the issues of resource allocation and co-channel interference management for coexistence of, and cooperation between, two long term evolution (LTE) networks. In the Republic of Korea, the LTE-based public safety (PS-LTE) network is being built for the 700-MHz frequency band. However, the same band is also allocated to the LTE-based high-speed railway (LTE-R) network, so immense interest and useful researches into co-channel interference management schemes are immediately needed. In this paper, we focus on the downlink system of coexisting PS-LTE and LTE-R networks by considering LTE-R radio access network (RAN) sharing and non–RAN sharing by PS-LTE users equipment (UEs) to analyze the co-channel interference. We also utilize cooperative communications schemes, such as coordinated multipoint (CoMP) and inter-cell interference coordination (ICIC) in order to resolve the problem of co-channel interference. We categorize the coexistence of PS-LTE and LTE-R networks into five different scenarios, and evaluate the performance of each scenario based on various performance indexes, such as UE average throughput, UE received interference, and UE outage probability. Moreover, users can achieve high throughput as well as obtain a better channel condition by using RAN sharing. In addition, we always provide the higher priority to railway user while allocating the resources for coexisting public safety and railway networks using LTE-R RAN sharing by PS-LTE UEs, because train control signal needs more reliable communication as well as low latency in order to fulfil its mission-critical service (MCS) demands. By employing coordinated scheduling (CS) CoMP, the highest throughput performance can be attained with RAN sharing. Furthermore, the dynamic ICIC enhances cell-edge UE performance and reduces UE received interference, as well as the outage probability, by using the partial reuse band and bonus band allocation.

Network Coding for Energy Efficient Transmission in Wireless Body Area Networks

Wireless Body Area Networks (WBANs) is a technology that has revolutionized the health-care industry by allowing remote monitoring, early detection and prevention of diseases. Patients can be remotely monitored thanks to implant devices in the body or by placing nodes on different parts of the body. Often the deployed sensor nodes are constraint by limited battery sources and are required to continuously collect the data and transfer it to the sink node, thus requiring energy efficient communication schemes. In addition, in poor channel conditions, this data collection and transfer results in retransmission thus wasting useful energy. This work presents a cooperative network coding based transmission technique for spectrum and energy efficiency in WBANs. The bit error rate (BER) of the network coded path in comparison to direct communication approach is explored. The effect of WBAN path loss due to different node positions is also discussed. It is observed that node position greatly affects path loss and received power which in turn affect the BERs. Simulation results show that network coded cooperative communication strategy in WBAN channel with and without combining outperforms as compared to direct communication.

Characterization of the On-Body Path Loss at 2.45 GHz and Energy Efficient WBAN Design for Dairy Cows

Wireless body area networks (WBANs) provide promising applications in the healthcare monitoring of dairy cows. The characterization of the path loss (PL) between on-body nodes constitutes an important step in the deployment of a WBAN. In this paper, the PL between nodes placed on the body of a dairy cow was determined at 2.45 GHz. Finite-difference time domain simulations with two half-wavelength dipoles placed 20 mm above a cow model were performed using a 3-D electromagnetic solver. Measurements were conducted on a live cow to validate the simulation results. Excellent agreement between measurements and simulations was achieved and the obtained PL values as a function of the transmitter–receiver separation were well fitted by a lognormal PL model with a PL exponent of 3.1 and a PL at reference distance (10 cm) of 44 dB. As an application, the packet error rate (PER) and the energy efficiency of different WBAN topologies for dairy cows (i.e., single-hop, multihop, and cooperative networks) were investigated. The analysis results revealed that exploiting multihop and cooperative communication schemes decrease the PER and increase the optimal payload packet size. The analysis results revealed that exploiting multihop and cooperative communication schemes increase the optimal payload packet size and improve the energy efficiency by 30%.

Adjustable Multiple Relay Selection Based on Steady-State Mean Square Joint Error for Cooperative Communication

In this paper, an adjustable multiple relay selection (MRS) scheme for cooperative communication with amplify-and-forward (AF) relay under frequency selective channels is proposed. In the proposed scheme, the relays are ordered firstly by the steady-state mean square error (MSE), then the relays are sequentially selected out from N relays and the number of cooperating relays is adjusted dynamically according to the steady-state mean square joint error (MSJE). The aim of this work is to dynamically estimate the optimum number N o of cooperating relays. Optimum means the minimum number of cooperating relays, N o , achieving the minimum level of steady-state MSJE. Numerical results verify the analyses and show that the scheme can adaptively adjust the number of cooperating relays, and outperform conventional relay selection schemes. Hence, the proposed scheme provides better tradeoff between BER performance and spectral efficiency and to save more energy in cooperative wireless networks.

Two-Hop Relay-Assisted Cooperative Communication in Wireless Body Area Networks

The pervasive use of wireless body area networks (BANs) has incurred potential inter-BAN interference, which can cause severe performance degradation. In this article, the coexistence of BANs is experimentally performed. A relay-assisted cooperative communications scheme is implemented in a real IEEE 802.15.4-based BAN system with a beacon-enabled mode and guaranteed time slot (GTS) scheduling. As far as we know, it is the first experimental work that enables real-time investigation of the effectiveness of cooperative communications in BANs for co-channel radio interference mitigation. First- and second-order statistics, including outage probability, level crossing rate (LCR), and average fade/nonfade duration, are calculated from the measured effective channel gains of the device-to-coordinator links across all superframes. Empirical results demonstrate significant advantages of using two-hop relay-assisted communications over traditional star topology BAN. Advantages include a maximum of a 10dB increase in channel gain threshold at an outage probability of 10%, which corresponds to a guideline for a 10% maximum packet error rate as specified in the IEEE BAN standard; a reduction in the level crossing rate by a factor of 5 at a channel gain threshold of − 100dB; and an average nonfade duration prolonged by a factor of 5 at the same threshold.

Spectrum-Efficient Resource Allocation Framework for Cooperative Opportunistic Wireless Networks

Dynamic spectrum access (DSA) is a promising approach to alleviate spectrum scarcity and improve spectrum utilization. Recently, several cooperative communication schemes have been proposed to further enhance spectrum utilization in DSA networks. Existing cooperation designs are either tailored for primary-secondary user (PU-SU) cooperation and not applicable to SU cooperation, or focus on the potential benefits of SUs cooperation without investigating how SUs agree on cooperating and the conditions that lead to improve their performance. In this paper, we introduce a spectrum-efficient resource allocation framework based on SUs cooperation, where the resources include the free spectrum access time, available channels, and relays. First, we formulate the interactions between the cooperating SUs and a PU using a discrete-time Markov chain (DTMC). Using this DTMC and Nash bargaining, we determine the new spectrum access times for SUs based on every nodes utility. We also derive the conditions under which all SUs improve their performance by cooperation. Second, considering a multi-channel multi-SU infrastructure network, we formulate two optimization problems for jointly allocating channels to SUs and selecting the cooperating SU pairs. We corroborate our analytical findings with detailed simulations that evaluate SUs cooperation gains and the optimality of the proposed joint allocation schemes.

Region based find and spray scheme for co-operative data communication in vehicular cyber-physical systems

AbstractSmart transportation in Vehicular Cyber Physical Systems (VCPS) are addressing a range of problems including reducing traffic accidents, congestion, fuel consumption, time spent on traffic jams, and to improve transportation safety. Smart transportation VCPS is expected to contribute an important role in the design and development of intelligent transportation systems. Intermittently Connected Vehicular Networks (ICVNs) are a kind of intelligent transportation systems, where due to mobility of vehicles there may be disconnections among the source and destination vehicles. A multi-hop scenario is used here, where a stationary road side unit exchanges data packets with a destination outside its communication range, using passing-by vehicles as information carriers. In order to deal with these ICVNs, an efficient routing scheme is necessary to withstand the maximum delay. We propose a routing scheme, which makes use of the movement history among the regions for routing a message. The proposed scheme ...

Adaptive Relay Selection and Data Transmission Scheme for Cooperative Communication

In this paper, an adaptive relay selection and transmission scheme are proposed for cooperative communication. As the conventional relay selection schemes, the best harmonic mean and the threshold-based relay selection scheme require channel state information (CSI) in advance at the source. By using CSI, they can select the optimal or the sub-optimal relay. But, the source does not know CSI as a priori information in general environment. Additionally, the conventional system uses the fixed maximum throughput regardless of channel state. The proposed relay selection scheme does not require a priori information at the source. It uses a characteristic of Reed---Solomon codes. By using it, the source can select the optimal relay for cooperative communication. Additionally, the proposed adaptive transmission scheme can change the maximum throughput according to the result of optimal relay selection. By using the proposed relay selection and adaptive transmission scheme, the proposed system is more reliable and adaptable according to selected relay.

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