- 11 Nguyen Dinh Chieu Str., Dist. 1, HoChiMinh City, Vietnam
Tran Trung Duy
PTIT, Telecommunications, Department Member
In this paper, the optimization of downlink beamforming vectors, uplink transmission power, and power-splitting factors is investigated for a secure two-way SWIPT network in the presence of a hidden eavesdropper and non-linear energy... more
In this paper, the optimization of downlink beamforming vectors, uplink transmission power, and power-splitting factors is investigated for a secure two-way SWIPT network in the presence of a hidden eavesdropper and non-linear energy harvesting circuits over both perfect and imperfect channels. The eavesdropper is inactive, so its channel information is not available at the base stations (BSs). The purpose of artificial noise is to create downlink interference with the hidden eavesdropper as much as possible, while satisfying the quality of service for two-way communications. For perfect downlink channels, the semidefinite relaxation (SDR) technique is exploited, and the optimal matrices are proven to satisfy rank-1 conditions, thus providing the optimal beamforming vectors. For imperfect downlink channel state information, we propose an iterative algorithm with a penalty function to obtain the approximate rank-1 matrices. On uplink, we attain the optimal transmission power for user...
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1 Original Article Combining Power Allocation and Superposition Coding for an Underlay Two-way Decode-and-forward Scheme Pham Ngoc Son, Tran Trung Duy, Phuc Quang Truong, Son Ngoc Truong, Pham Viet Tuan, Van-Ca Phan, Khuong Ho-Van Ho Chi... more
1 Original Article Combining Power Allocation and Superposition Coding for an Underlay Two-way Decode-and-forward Scheme Pham Ngoc Son, Tran Trung Duy, Phuc Quang Truong, Son Ngoc Truong, Pham Viet Tuan, Van-Ca Phan, Khuong Ho-Van Ho Chi Minh City University of Technology and Education, Vo Van Ngan Street, Thu Duc City, Ho Chi Minh City, Vietnam Posts and Telecommunications Institute of Technology, Nguyen Dinh Chieu Street, District 1, Ho Chi Minh City, Vietnam University of Education, Hue University, Le Loi Street, Hue City, Vietnam Ho Chi Minh City University of Technology (HCMUT), Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam Vietnam National University Ho Chi Minh City, Ho Chi Minh City, Vietnam
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In this study, we consider multiuser multi-input single-output (MISO) beamforming design in underlay cognitive radio networks in the presence of a primary user (PU) and eavesdropper (Eve). We propose a multi-objective optimization problem... more
In this study, we consider multiuser multi-input single-output (MISO) beamforming design in underlay cognitive radio networks in the presence of a primary user (PU) and eavesdropper (Eve). We propose a multi-objective optimization problem (MOOP) for balancing two conflicting design objectives: maximizing the total intended power received at secondary receivers and minimizing the interference power at the PU, while satisfying the secrecy rate and PU interference threshold constraints. The MOOP was solved by a weighted sum method and semidefinite programming relaxation (SDR), and the rank-one optimal solutions were drawn with explanations. The upper and lower bounds were found by solving the single-objective and zero-forcing beamforming problems. The simulation results demonstrated a trade-off between the objectives in the Pareto optimal set, no improvement of performance with artificial noise, and better results with increasing number of transmission antennas.
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In this paper, we propose three path selection methods for cluster-based cognitive radio (CR) networks for secrecy enhancement by formulating the probability of non-zero secrecy capacity (PNSC). In the proposed work, it is assumed that... more
In this paper, we propose three path selection methods for cluster-based cognitive radio (CR) networks for secrecy enhancement by formulating the probability of non-zero secrecy capacity (PNSC). In the proposed work, it is assumed that uniform transmit power for the secondary transmitters and jammers must be adjusted to guarantee quality of service (QoS) of the primary network, follows a simple and efficient power allocation strategy. To improve the channel capacity, the best receiver is selected at each cluster to relay the source data to the next hop. Additionally, a jammer is randomly chosen at each cluster to generate noises on an eavesdropper, and to reduce the quality of the eavesdropping links. Three methods are studied in this paper. First, we propose the BEST path selection method (BEST) to maximize the end-to-end instantaneous secrecy capacity. Second, the path obtaining the MAXimum Value for the average end-to-end PNSC (MAXV) is selected for data transmission. Third, we also propose a RAND method in which a RANDom path is employed. For performance evaluation and comparison, we derive exact closed-form expressions for the end-to-end PNSC of the BEST, MAXV and RAND methods over Rayleigh fading channel. Monte Carlo simulations are then performed to verify the derived theoretical results.
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In this paper, we evaluate throughput of a power beacon-aided multi-hop relaying networks employing non-orthogonal multiple access (NOMA). In the proposed protocol, the source data are sent to the destination via the multi-hop... more
In this paper, we evaluate throughput of a power beacon-aided multi-hop relaying networks employing non-orthogonal multiple access (NOMA). In the proposed protocol, the source data are sent to the destination via the multi-hop transmission model. In addition, the source and relay nodes have to harvest energy the radio frequency (RF) signals generated by a power beacon. For performance evaluation, we derive an exact closed-form expression of throughput for the proposed scheme over Rayleigh fading channel and under impact of imperfect transceiver hardware. We finally perform simulation results to verify the theoretical results.
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In this paper, we propose joint relay and jammer selection protocols to enhance secrecy performance for cluster-based multi-hop networks. In particular, without channel state information (CSI) of the eavesdropping links, one of available... more
In this paper, we propose joint relay and jammer selection protocols to enhance secrecy performance for cluster-based multi-hop networks. In particular, without channel state information (CSI) of the eavesdropping links, one of available nodes at each cluster is selected to forward the source data, relying on the CSI of the data links, while a jammer node is randomly chosen to generate artificial noises to an eavesdropper. We also investigate the impact of hardware noises on the secrecy performance of the proposed protocols. When the transceiver hardware is perfect, we derive exact closed-form expressions of secrecy outage probability (SOP) for the proposed protocols over Rayleigh fading channel. We then perform Monte Carlo based computer simulations to verify the theoretical results.
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In this paper, we evaluate performances of various user selection protocols under impact of hardware impairments. In the considered protocols, a Base Station (BS) selects one of available Users (US) to serve, while the remaining USs... more
In this paper, we evaluate performances of various user selection protocols under impact of hardware impairments. In the considered protocols, a Base Station (BS) selects one of available Users (US) to serve, while the remaining USs harvest the energy from the Radio Frequency (RF) transmitted by the BS. We assume that all of the US randomly appear around the BS. In the Random Selection Protocol (RAN), the BS randomly selects a US to transmit the data. In the second proposed protocol, named Minimum Distance Protocol (MIND), the US that is nearest to the BS will be chosen. In the Optimal Selection Protocol (OPT), the US providing the highest channel gain between itself and the BS will be served. For performance evaluation, we derive exact and asymptotic closed-form expressions of average Outage Probability (OP) over Rayleigh fading channels. We also consider average harvested energy per a US. Finally, Monte-Carlo simulations are then performed to verify the theoretical results.
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In this paper, we propose an adaptive spectrum access protocol for secondary users (SUs) be used to access licensed bands in cognitive radio networks. Specifically, if the primary network, which uses multicast communication to transmit... more
In this paper, we propose an adaptive spectrum access protocol for secondary users (SUs) be used to access licensed bands in cognitive radio networks. Specifically, if the primary network, which uses multicast communication to transmit data from one primary source to multiple primary destinations, satisfies a required system quality of service (QoS), SUs can access the licensed bands, follows an underlay spectrum sharing. Otherwise, a secondary base (SB) station must assist the primary network in obtaining the QoS so that it can find opportunities to use the bands, i.e., cooperation-based spectrum access. To enhance the performance for the secondary network, in terms of outage probability (OP), various best-user selection methods are proposed. Moreover, we take into consideration the impact of hardware impairments on the OP of both primary and secondary networks. We derive exact and asymptotic closed-form expressions of the OP over Rayleigh fading channel. From the analytical results, an optimal value of maximal interference threshold and an optimal fraction of the SBs’ transmit power to the primary data are obtained when the secondary network operates on the underlay and the cooperation-based spectrum access modes, respectively. Finally, Monte Carlo simulations are performed to verify the theoretical derivations.
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In this paper, we propose a transmit antenna selection (TAS) protocol exploiting Fountain codes for secure communication. In the proposed protocol, a base station (BS) selects its best antenna to transmit Fountain packets to a legitimate... more
In this paper, we propose a transmit antenna selection (TAS) protocol exploiting Fountain codes for secure communication. In the proposed protocol, a base station (BS) selects its best antenna to transmit Fountain packets to a legitimate user (US). Moreover, a cooperative jammer (JA) is used to generate artificial noises to an eavesdropper (EA). The transmission between BS and US will terminate as soon as US can receive a sufficient number of the encoded packets for decoding the original message. To obtain a secure communication, US must receive enough the number of the packets before EA can. Under impact of hardware noises at all of the nodes, we derive expressions of probability of successful and secure communication (SSC), intercept probability (IP) and average number of the packets transmitted by BS over Rayleigh fading channel. Monte Carlo simulations are presented to verify the theoretical results.
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In this paper, we propose an energy-harvesting based decode-and-forward multi-hop cognitive relay protocol, where secondary users harvest energy from the radio frequency signals transmitted by multiple dedicated power beacons (PBs) to... more
In this paper, we propose an energy-harvesting based decode-and-forward multi-hop cognitive relay protocol, where secondary users harvest energy from the radio frequency signals transmitted by multiple dedicated power beacons (PBs) to support the information transmission. The secondary transmitters including source and relays must adjust their transmit power to satisfy interference power constraints required by multiple primary receivers (PRs). For performance evaluation, we derive exact closed-form expressions of outage probability (OP) for the proposed method over Rayleigh fading channel. Moreover, the asymptotic expressions for the outage performance at high and low signal-to-noise (SNR) are given to provide insights into the system performance. Then, Monte Carlo simulations are performed to verify the analysis results. The obtained results presented that the outage performance of the proposed system significantly depends on the number of PBs, the interference constraint as well as the position of PBs and PRs. Finally, the analytical asymptotic results show that the optimal time splitting ratio only depends on the number of hops and the number of PBs at low transmit signal-to-noise ratio (SNR).
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In this paper, we study the trade-off between security and reliability for multi-hop cognitive mobile-to-mobile (M2M) networks. In the proposed scheme, a secondary source sends its data to a secondary destination with assistance of... more
In this paper, we study the trade-off between security and reliability for multi-hop cognitive mobile-to-mobile (M2M) networks. In the proposed scheme, a secondary source sends its data to a secondary destination with assistance of multiple secondary relays in presence of a secondary eavesdropper. The secondary transmitters operate on an underlay spectrum access mode where their transmit power must satisfy interference constraints required by primary users. We derive exact closed-form expressions of the end-to-end outage probability (OP) and intercept probability (IP) for the secondary network over double Rayleigh fading channels. Then, simulations are presented to verify the derived expressions as well as to show the trade-off between OP and IP, and the impact of hardware imperfection, the number of hops and the number of primary users on the performance metrics.
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In this paper, we consider a two-user downlink full-duplex (FD) non-orthogonal multiple access (NOMA) relay system where the FD relay uses an energy harvesting (EH) technique to assist the communication between the base station and far... more
In this paper, we consider a two-user downlink full-duplex (FD) non-orthogonal multiple access (NOMA) relay system where the FD relay uses an energy harvesting (EH) technique to assist the communication between the base station and far user over flat, independent and non-identically Rayleigh fading channels. Importantly, since the relay operates in FD mode, we take into account the effect of the interference caused by relay on the near user. Considering this EH-FD-NOMA relay system, we derive the exact mathematical expressions of the outage probabilities and ergodic capacities of near and far users. Monte–Carlo simulations verify the accuracy of our analytical method. Numerical results provided in this paper allow system designers to clearly see not only the impacts of the power distribution factor and the self-interference cancellation capacity of the relay but also the influence of the strength of inter-user interference at the near user on the outage performances and ergodic capa...
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In this paper, we consider a multi-hop relaying protocol using beacon-assisted energy harvesting. In the proposed protocol, a source encodes its data by Fountain codes, and sends encoded packets to a destination via intermediate relays.... more
In this paper, we consider a multi-hop relaying protocol using beacon-assisted energy harvesting. In the proposed protocol, a source encodes its data by Fountain codes, and sends encoded packets to a destination via intermediate relays. An eavesdropper who appears around the destination attempts to receive the encoded packets for the data recovery. For performance evaluation, we derive exact expressions of outage probability (OP) and intercept probability (IP) over Rayleigh fading channels under impact of hardware impairments. Computer simulations are then performed to verify our derivations.
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In this paper, we study performances of multi-hop transmission protocols in underlay cognitive radio (CR) networks under impact of transceiver hardware impairment. In the considered protocols, cooperative communication is used to enhance... more
In this paper, we study performances of multi-hop transmission protocols in underlay cognitive radio (CR) networks under impact of transceiver hardware impairment. In the considered protocols, cooperative communication is used to enhance reliability of data transmission at each hop on an established route between a secondary source and a secondary destination. For performance evaluation, we derive exact and asymptotic closed-form expressions of outage probability and average number of time slots over Rayleigh fading channel. Then, computer simulations are performed to verify the derivations. Results present that the cooperative -based multi-hop transmission protocols can obtain better performance and diversity gain, as compared with multi-hop scheme using direct transmission (DT). However, with the same number of hops, these protocols use more time slots than the DT protocol.
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In this paper, we propose a hybrid spectrum sharing approach in cognitive radio networks. If the primary network satisfies the required quality of service (QoS), an underlay approach can be applied for the secondary network. Otherwise,... more
In this paper, we propose a hybrid spectrum sharing approach in cognitive radio networks. If the primary network satisfies the required quality of service (QoS), an underlay approach can be applied for the secondary network. Otherwise, the secondary network must help primary network obtain the QoS and hence it must operate on overlay mode. We also derive the closed-formed expressions of the outage probability for the secondary network over Rayleigh fading channels. Monte-Carlo simulations are then presented to verify our derivations.
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In this paper, we propose and evaluate performance of multihop multipath underlay cognitive radio networks. In a primary network, an uplink nonorthogonal multiple access method is employed to allow primary transmitters to simultaneously... more
In this paper, we propose and evaluate performance of multihop multipath underlay cognitive radio networks. In a primary network, an uplink nonorthogonal multiple access method is employed to allow primary transmitters to simultaneously transmit their data to a primary receiver. Using an underlay spectrum-sharing method, secondary source and secondary relays must adjust their transmit power to guarantee quality of service of the primary network. Under the limited transmit power, cochannel interference from the primary transmitters, and hardware noises caused by impairments, we propose best-path selection methods to improve the end-to-end performance for the secondary network. Moreover, both multihop decode-and-forward and amplify-and-forward relaying protocols are considered in this paper. We derive expressions of outage probability for the primary and secondary networks and propose an efficient method to calculate the transmit power of the secondary transmitters. Then, computer sim...
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In this paper, we evaluate end-to-end outage probability of a multi-hop decode-and-forward relaying protocol in underlay cognitive radio network. In the proposed protocol, named COOP, secondary nodes including source and relays have to... more
In this paper, we evaluate end-to-end outage probability of a multi-hop decode-and-forward relaying protocol in underlay cognitive radio network. In the proposed protocol, named COOP, secondary nodes including source and relays have to harvest radio-frequency energy from multiple secondary power beacons, and adjust their transmit power, follows a pre-determined interference threshold given by multiple primary users. To enhance the outage performance for the secondary network under an joint constraint of the interference threshold, Rayleigh fading channel and hardware noises caused by imperfect transceiver hardware, the secondary relays on the source-destination path cooperate to forward the source data to the destination. Particularly, they attempt to receive the source data from their previous nodes, and forward it to the secondary destination if requested. Moreover, whenever the destination cannot receive the source data successfully, a successful relay that has the shortest dista...
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In this paper, we propose an underlay two-way relaying scheme with the successive interference cancellation (SIC) solution in which two secondary sources transmit simultaneously their data to each other through secondary relays. The... more
In this paper, we propose an underlay two-way relaying scheme with the successive interference cancellation (SIC) solution in which two secondary sources transmit simultaneously their data to each other through secondary relays. The proposed scheme is operated in only two time slots and under an interference constraint of a primary receiver, denoted as the UTW-2TS scheme. In the UTW-2TS scheme, the secondary relays employ the SIC operation to decode successively the data from received broadcast signals and then encode these data by two techniques: digital network coding (DNC) enforced by XOR operations (denoted as the UTW-2TS-DNC protocol) and superposition coding (SC) enforced by power domain additions (denoted as the UTW-2TS-SC protocol). A selected secondary relay which subjects to maximize decoding capacities and to minimize collection time of channel state information in two protocols UTW-2TS-DNC and UTW-2TS-SC experiences residual interferences from imperfect SIC operations. O...
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In this paper, we propose and evaluate the performance of fountain codes (FCs) based secure transmission protocols in multiple-input-multiple-output (MIMO) wireless systems, in presence of a passive eavesdropper. In the proposed... more
In this paper, we propose and evaluate the performance of fountain codes (FCs) based secure transmission protocols in multiple-input-multiple-output (MIMO) wireless systems, in presence of a passive eavesdropper. In the proposed protocols, a source selects its best antenna to transmit fountain encoded packets to a destination that employs selection combining (SC) or maximal ratio combing (MRC) to enhance reliability of the decoding. The transmission is terminated when the destination has a required number of the encoded packets to reconstruct the original data of the source. Similarly, the eavesdropper also has the ability to recover the source data if it can intercept a sufficient number of the encoded packets. To reduce the number of time slots used, the source can employ non-orthogonal multiple access (NOMA) to send two encoded packets to the destination at each time slot. For performance analysis, exact formulas of average number of time slots (TS) and intercept probability (IP)...
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In this paper, we study physical-layer security issue of secondary networks in cognitive radio (CR). In the considered system model, a secondary source communicates with a secondary destination with assistance of multiple secondary relays... more
In this paper, we study physical-layer security issue of secondary networks in cognitive radio (CR). In the considered system model, a secondary source communicates with a secondary destination with assistance of multiple secondary relays in presence of multiple secondary eavesdroppers. The secondary users operate on an underlay mode, where they must adjust their transmit power to satisfy interference constraints required by primary users. Moreover, we propose three efficient relay selection methods to improve outage performance for the data links as well as to reduce decoding probability (DP) of the eavesdropping links. For performance evaluation and comparison, we derive exact closed-form expressions of outage probability (OP) and decoding probability (DP) over Rayleigh fading channel under impact of imperfect hardware transceiver. Finally, Monte Carlo simulations are performed to verify our theoretical derivations. The results present that with the presence of the eavesdroppers, ...
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Muscle Fiber Conduction Velocity (MFCV) can be calculated from the time delay between the surface electromyographic (sEMG) signals recorded by electrodes aligned with the fiber direction. In order to take into account the non-stationarity... more
Muscle Fiber Conduction Velocity (MFCV) can be calculated from the time delay between the surface electromyographic (sEMG) signals recorded by electrodes aligned with the fiber direction. In order to take into account the non-stationarity during the dynamic contraction (the most daily life situation) of the data, the developed methods have to consider that the MFCV changes over time, which induces time-varying delays and the data is non-stationary (change of Power Spectral Density (PSD)). In this paper, the problem of TVD estimation is considered using a parametric method. First, the polynomial model of TVD has been proposed. Then, the TVD model parameters are estimated by using a maximum likelihood estimation (MLE) strategy solved by a deterministic optimization technique (Newton) and stochastic optimization technique, called simulated annealing (SA). The performance of the two techniques is also compared. We also derive two appropriate Cramer–Rao Lower Bounds (CRLB) for the estima...
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In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets... more
In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets to a destination in presence of an eavesdropper. Moreover, a cooperative jammer node harvests energy from radio frequency (RF) signals of the source and the interference sources to generate jamming noises on the eavesdropper. The data transmission terminates as soon as the destination can receive a sufficient number of the encoded packets for decoding the original data of the source. To obtain secure communication, the destination must receive sufficient encoded packets before the eavesdropper. The combination of the TAS and harvest-to-jam techniques obtains the security and efficient energy via reducing the number of the data transmission, increasing the quality of the data channel, decreasing the quality of the eavesdropping channel, and supportin...
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In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the... more
In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the assistance of multiple secondary relays. In addition, there exists a secondary eavesdropper who tries to overhear the source data. Under a maximum interference level required by a primary user, the secondary source and relay nodes must adjust their transmit power. We first formulate effective signal-to-interference-plus-noise ratio (SINR) as well as secrecy capacity under the constraints of the maximum transmit power, the interference threshold and the hardware impairment level. Furthermore, when the hardware impairment level is relaxed, we derive exact and asymptotic expressions of end-to-end secrecy outage probability over Rayleigh fading channels by using the recursive method. The derived expressions were verified by simulations, in which the proposed sc...
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In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna... more
In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Raylei...
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Research Interests: Mechanical Engineering, Computer Science, Encryption, Energy Harvesting, Computer Network, and 9 moreOutage Probability, Wireless Sensor Networks (WSNs), Physical layer security, RELAY, Eavesdropping, Path Selection, Wireless Sensor Network, Electrical And Electronic Engineering, and Multipath Propagation
To solve the problem of energy constraints and spectrum scarcity for cognitive radio wireless sensor networks (CR-WSNs), an underlay decode-and-forward relaying scheme is considered, where the energy constrained secondary source and relay... more
To solve the problem of energy constraints and spectrum scarcity for cognitive radio wireless sensor networks (CR-WSNs), an underlay decode-and-forward relaying scheme is considered, where the energy constrained secondary source and relay nodes are capable of harvesting energy from a multi-antenna power beacon (PB) and using that harvested energy to forward the source information to the destination. Based on the time switching receiver architecture, three relaying protocols, namely, hybrid partial relay selection (H-PRS), conventional opportunistic relay selection (C-ORS), and best opportunistic relay selection (B-ORS) protocols are considered to enhance the end-to-end performance under the joint impact of maximal interference constraint and transceiver hardware impairments. For performance evaluation and comparison, we derive the exact and asymptotic closed-form expressions of outage probability (OP) and throughput (TP) to provide significant insights into the impact of our propose...
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In this paper, we study physical-layer security (PLS) issue in underlay cognitive radio (UCR) networks in presence of multiple primary users (PUs). In particular, we propose three relay selection methods that take the interference... more
In this paper, we study physical-layer security (PLS) issue in underlay cognitive radio (UCR) networks in presence of multiple primary users (PUs). In particular, we propose three relay selection methods that take the interference constraint into account to improve the reliability of the data transmission as well as to reduce the data rate received at eavesdroppers. The main contribution of this work is to derive exact closed-form expressions of the intercept probability (IP) for the eavesdropping link and the outage probability (OP) on the data link under the impact of hardware impairments. The derived expressions are verified by Monte Carlo simulations.
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This paper investigates impact of hardware impairments on the probability of Non-zero Secrecy Capacity (NSC) of multi-hop relay networks. In the considered protocol, multiple eavesdroppers attempt to overhear the data that is relayed from... more
This paper investigates impact of hardware impairments on the probability of Non-zero Secrecy Capacity (NSC) of multi-hop relay networks. In the considered protocol, multiple eavesdroppers attempt to overhear the data that is relayed from a source to a destination via multiple intermediate relay nodes. To enhance the secrecy performance, the multi-hop randomize-and-forward (RF) strategy is used to confuse the eavesdroppers. We derive exact expressions of the NSC probability in integral forms over Rayleigh fading channels. Moreover, these formulas are then expressed by sums of infinite series of exponential functions and exponential integral functions. Finally, Monte Carlo simulations are performed to verify our derivations.
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The performance of single-input multiple-output (SIMO) cognitive spectrum sharing networks with the presence of equally correlated Rayleigh fading channels is investigated. In particular, based on the truncated infinitive series... more
The performance of single-input multiple-output (SIMO) cognitive spectrum sharing networks with the presence of equally correlated Rayleigh fading channels is investigated. In particular, based on the truncated infinitive series of cumulative distribution function (CDF) and probability density function (PDF) of the end-to-end signal-to-noise ratios (SNRs), close-form expressions are provided for the system outage performance, bit error rate and ergodic capacity. It is shown that the system performance merely depends on the correlation coefficient between antennas. Monte-Carlo simulations are also contributed to confirm the accuracy of our analysis.
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In this paper, we evaluate outage probability of dual- hop cooperative cognitive networks under impact of hardware impairment. In particular, we propose two relay selection methods to compensate the performance loss due to the imperfect... more
In this paper, we evaluate outage probability of dual- hop cooperative cognitive networks under impact of hardware impairment. In particular, we propose two relay selection methods to compensate the performance loss due to the imperfect hardware and the interference constraint at primary network. In the first proposed method, named PRO, the best secondary relay is selected by relying on the channel state information (CSI) of the links between the secondary source and the secondary relays. In the second one, named RE, one of active relays which provides the highest channel gain to the secondary destination is chosen for the cooperation. At the secondary destination, the maximal ratio combining (MRC) technique is used to combine the data received from the source and the selected relay. For performance evaluation and comparison, we drive exact closed- form expressions of outage probability over Rayleigh fading channel, which are verified by Monte Carlo simulations.
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Relaying transmission enables the high performance of wireless communication systems. Therefore, many researches have investigated this technique. However, most of the studies supposed the ideal-hardware and ignored the co-channel... more
Relaying transmission enables the high performance of wireless communication systems. Therefore, many researches have investigated this technique. However, most of the studies supposed the ideal-hardware and ignored the co-channel interference. For accuracy design, it highly motivates to account for hardware impairment and interference in analyzing relaying systems. In this paper, we model the multi-hop relaying channel, considering both hardware impairment and co-channel interference. We then analyze the performance of the system in terms of outage probability and ergodic capacity. Specially, the exact and asymptotic (at high signal-to-noise and interference ratio) closedform expressions of outage probability and ergodic capacity are both given over Rayleigh fading channels.
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In this paper, we propose an energy harvesting-based spectrum access model in overlay cognitive radio (CR). In the proposed scheme, one of potential secondary transmitters (STs) is selected to help a primary transmitter (PT) forward... more
In this paper, we propose an energy harvesting-based spectrum access model in overlay cognitive radio (CR). In the proposed scheme, one of potential secondary transmitters (STs) is selected to help a primary transmitter (PT) forward primary signals to a primary receiver (PR). The chosen ST harvests energy from the PT's signals to serve the PT-PR communication as well as find opportunities to access licensed bands. Moreover, the primary network employs incremental cooperative communication in which the PR requires the assistance from the STs only when the transmission between PT and PR is not successful. For performance evaluation, we derive lower-bound closed-form expressions of outage probability for both secondary and primary networks over Rayleigh fading channel. Monte-Carlo simulations are performed to verify theoretical results. The results present that the outage performance of the primary network can be enhanced significantly due to the cooperation of the STs, while that of the secondary network mainly depends on the transmit power of the PT.
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This paper considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all communication links are non-line of sight ones and their fading is modeled by the double Rayleigh fading distribution. Roadside relays... more
This paper considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all communication links are non-line of sight ones and their fading is modeled by the double Rayleigh fading distribution. Roadside relays (or access points) implementing the decode-and-forward (DF) relaying protocol are employed and one of them is selected according to a predetermined policy in order to enable communication between vehicles. The performance of the considered cognitive cooperative system is investigated for Kth best partial and full relay selection (RS) as well as for two distinct fading scenarios. In the first scenario, all channels are double Rayleigh distributed. In the second scenario, only the secondary source to relay and relay to destination channels are considered to be subject to double Rayleigh fading whereas, channels between the secondary transmitters and the primary user are modeled by the Rayleigh distribution. Exact and approximate expressions for the outage probability performance for all considered RS policies and fading scenarios are presented. In addition to the analytical results, complementary computer simulated performance evaluation results have been obtained by means of Monte Carlo simulations. The perfect match between these two sets of results has verified the accuracy of the proposed mathematical analysis.