scholarly journals Interference Alignment in Multi-Hop Cognitive Radio Networks under Interference Leakage

2018 ◽  
Vol 8 (12) ◽  
pp. 2486 ◽  
Author(s):  
Eylem Erdogan ◽  
Sultan Çolak ◽  
Hakan Alakoca ◽  
Mustafa Namdar ◽  
Arif Basgumus ◽  
...  
Keyword(s):  
Cognitive Radio ◽  
Interference Alignment ◽  
Ergodic Capacity ◽  
Secondary Source ◽  
Primary Network ◽  
Secondary Network ◽  
The Impact ◽  
Secondary Networks ◽  
Diversity Gains ◽  
Multiple Primary Users

In this work, we examine the interference alignment (IA) performance of a multi-input multi-output (MIMO) multi-hop cognitive radio (CR) network in the presence of multiple primary users. In the proposed architecture, it is assumed that linear IA is adopted at the secondary network to alleviate the interference between primary and secondary networks. By doing so, the secondary source can communicate with the secondary destination via multiple relays without causing any interference to the primary network. Even though linear IA can suppress the interference in CR networks considerably, interference leakages may occur due to a fast fading channel. To this end, we focus on the performance of the secondary network for two different cases: (i) the interference is perfectly aligned; (ii) the impact of interference leakages. For both cases, closed-form expressions of outage probability and ergodic capacity are derived. The results, which are validated by Monte Carlo simulations, show that interference leakages can deteriorate both system performance and the diversity gains considerably.

scholarly journals Performance Enhancement for Multihop Cognitive DF and AF Relaying Protocols under Joint Impact of Interference and Hardware Noises: NOMA for Primary Network and Best-Path Selection for Secondary Network

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tran Trung Duy ◽  
Pham Thi Dan Ngoc ◽  
Phuong T. Tran
Keyword(s):  
Spectrum Sharing ◽  
Performance Enhancement ◽  
Path Selection ◽  
Secondary Source ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Transmit Power ◽  
Primary Network ◽  
Secondary Network ◽  
Relaying Protocols

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 simulations employing the Monte-Carlo approach are realized to validate the derivations.

scholarly journals Outage performance of underlay cognitive radio networks over mix fading environment

2021 ◽  
Vol 11 (3) ◽  
pp. 2019
Author(s):  
Nguyen Hong Nhu ◽  
Cuu_Ho Van ◽  
Van-Duc Phan ◽  
Tan N. Nguyen ◽  
Miroslav Voznak ◽  
...  
Keyword(s):  
Cognitive Radio ◽  
Fading Channels ◽  
System Performance ◽  
Relay Node ◽  
Ergodic Capacity ◽  
Radio Networks ◽  
Closed Form Expression ◽  
Destination Node ◽  
Secondary Source ◽  
Underlay Cognitive Radio

In this paper, the underlay cognitive radio network over mix fading environment is presented and investigated. A cooperative cognitive system with a secondary source node S, a secondary destination node D, secondary relay node Relay, and a primary node P are considered. In this model system, we consider the mix fading environment in two scenarios as Rayleigh/Nakagami-m and Nakagami-m/Rayleigh Fading channels. For system performance analysis, the closed-form expression of the system outage probability (OP) and the integral-formed expression of the ergodic capacity (EC) are derived in connection with the system's primary parameters. Finally, we proposed the Monte Carlo simulation for convincing the correctness of the system performance.

scholarly journals Studying strictly positive secure capacity in cognitive radio-based non-orthogonal multiple access

2021 ◽  
Vol 10 (2) ◽  
pp. 848-855
Author(s):  
Chi-Bao Le ◽  
Dinh-Thuan Do
Keyword(s):  
Cognitive Radio ◽  
Multiple Access ◽  
Access Network ◽  
Simulation Method ◽  
Secondary User ◽  
Secondary Source ◽  
Channel State ◽  
Secondary Network ◽  
Fixed Power ◽  
Multiple Relay

This paper studies a downlink security-aware secure outage performance in the secondary network of cognitive radio-assisted non-orthogonal multiple access network (CR-NOMA). The multiple relay is employed to assist transmission from the secondary source to destinations. The security-aware performance is subject to constraints in fixed power allocation factor assigned to each secondary user. The security-aware secure performance is based on channel state information (CSI) at the physical layer in which an eavesdropper intends to steal information. According to the considered system, exact expressions of Strictly positive secure capacity (SPSC) are proved to analyze system in terms of secure performance. Finally, the secondary user secure problem is evaluated via Monte-Carlo simulation method. The main results indicate that the secure performance of proposed system can be improved significantly.

scholarly journals Analysis of Efficient Spectrum Handoff in a Multi-Class Hybrid Spectrum Access Cognitive Radio Network Using Markov Modelling

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4120 ◽  
Author(s):  
Atif Shakeel ◽  
Riaz Hussain ◽  
Adeel Iqbal ◽  
Irfan Latif Khan ◽  
Qadeer ul Hasan ◽  
...  
Keyword(s):  
Cognitive Radio ◽  
Substantial Improvement ◽  
System Throughput ◽  
Spectrum Access ◽  
Spectrum Utilization ◽  
Markov Modelling ◽  
Spectrum Handoff ◽  
Delay Sensitive ◽  
Primary Network ◽  
The Impact

Cognitive radio networks (CRNs) rely on sensing of the licensed spectrum of a primary network to dynamically ascertain underutilized portion of the spectrum, thus affording additional communication opportunities. In a CRN, a single homogeneous spectrum access, such as interweave only deprives the secondary users (SUs) of channel access during handoff, particularly at high primary network traffic. Therefore, providing quality-of-service (QoS) to multi-class SUs with diverse delay requirements during handoff becomes a challenging task. In this paper, we have evolved a Markov-based analytical model to ascertain the gain in non-switching spectrum handoff scheme for multi-class SUs employing hybrid interweave-underlay spectrum access strategy. To satisfy the QoS requirements of the delay-sensitive traffic, we have analyzed the impact of hybrid spectrum access scheme for prioritized multi-class SUs traffic. The results show substantial improvement in spectrum utilization, average system throughput and extended data delivery time compared to conventional CRN using interweave only spectrum access. This demonstrates the suitability of the proposed scheme towards meeting QoS requirements of the delay-sensitive SU traffic while improving the overall performance for delay-tolerant SU traffic as well.

scholarly journals On Performance Analysis of Underlay Cognitive Radio-Aware Hybrid OMA/NOMA Networks with Imperfect CSI

Electronics ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 819 ◽  
Author(s):  
Dinh-Thuan Do ◽  
Anh-Tu Le ◽  
and Byung Moo Lee
Keyword(s):  
Cognitive Radio ◽  
Outage Probability ◽  
Power Allocation ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Primary Source ◽  
Primary Network ◽  
Secondary Network ◽  
Target Rates ◽  
Allocation Factor

This study considers the outage and throughput performance of downlink in the secondary network of cognitive radio assisted non-orthogonal multiple access (NOMA) systems. Both orthogonal multiple access (OMA) mode and NOMA mode are investigated with respect to status of decoding operation of each user. Depending on the transmit signal-to-noise ratio (SNR) at the primary source and interference constraint from the primary network, the closed-form expressions of the outage probability for two users are obtained and compared in terms of performance. To obtain further insights, an asymptotic analysis of the outage probability in the high SNR regime is presented. Optimal throughput also provides insight in the computation of the power allocation factor. Furthermore, power allocation factor, target rates, and transmit SNR are evaluated to obtain reasonable outage performance. Monte Carlo simulations are conducted to confirm the analytical results.

Problems Arising from Redefinition in Densification Surveys

1974 ◽  
Vol 28 (5) ◽  
pp. 732-738
Author(s):  
Adam Chrzanowski ◽  
Nicholas Canellopoulos
Keyword(s):  
Higher Order ◽  
Relative Accuracy ◽  
Control Network ◽  
Primary Control ◽  
Primary Network ◽  
Secondary Network ◽  
Fitting Method ◽  
Secondary Networks ◽  
Better Than

The redefinition has been considered as a necessary step to improve the primary control network, which at the present does not satisfy the accuracy requirements of all the users. In view of the existing distortions in the primary control and in view of the forthcoming redefinition, the user who is involved in a densification survey faces the following questions: 1) how to perform the adjustment of the secondary networks in order to be independent of the distortion of the primary network, 2) how to take the advantage of those parts of the primary network that satisfy his requirements. If the two questions are answered, one has to solve a problem on how to transform, in the best way, the established secondary network into the redefined coordinates system. The authors try to give an answer to those questions considering the following four cases: 1) the relative accuracy between the higher order points is much better than the relative accuracy of the same points belonging to the densification network; 2) both primary and densification methods have the same accuracy; 3) the relative accuracy of the higher order network is worse than the corresponding of the densification network; 4) the relative accuracy of the points of the higher order network is unknown. The authors advocate that a free adjustment and a fitting method should answer the problem.

scholarly journals Operation analysis of primary and secondary networks of distributed solar heating system in Tibet

2021 ◽  
Vol 329 ◽  
pp. 01079
Author(s):  
Chengpeng Liu
Keyword(s):  
Heating System ◽  
Solar Heating ◽  
Temperature Changes ◽  
Operation Analysis ◽  
Primary Network ◽  
Secondary Network ◽  
High Altitude Area ◽  
Distributed Heating ◽  
Secondary Networks ◽  
Operation Characteristics

Tibet is located in a high cold and high altitude area. Heating in winter is an important problem to be solved urgently, and the distributed solar heating system provides a solution for the efficient and clean utilization of energy in this area. Through the test and commissioning of the distributed solar heating system with supplementary combustion in Tibet, the operation characteristics of the heating system are analyzed from the temperature changes of the primary network and the secondary network. The research results can provide technical support for the application and promotion of the solar distributed heating system with supplementary combustion in Tibet.

scholarly journals Connectivity Analysis of Cognitive Radio Ad-Hoc Networks with Multi-Pair Primary Networks

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 565 ◽  
Author(s):  
Le Dung ◽  
Seong-Gon Choi
Keyword(s):  
Cognitive Radio ◽  
Ad Hoc Networks ◽  
Ad Hoc ◽  
Simulation Analysis ◽  
Secondary Users ◽  
Mathematical Expressions ◽  
Primary Network ◽  
Secondary Network ◽  
Interference Range ◽  
Hoc Networks

In this paper, we study the connectivity of cognitive radio ad-hoc networks (CRAHNs) where primary users (PUs) and secondary users (SUs) are randomly distributed in a given area following a homogeneous Poisson process. Moreover, for the sake of more realistic CRAHNs, contrary to previous works in the literature, we consider the case that primary network is comprised of multiple communication pairs which are spatial-temporal distributed in the network area. We also take into consideration the differences in transmission range and interference range of both PUs and SUs. The connectivity of such CRAHN is studied from three viewpoints. First, we mathematically analyze the probability of isolated secondary transmitter and secondary receiver. Second, we derive the approximation expression of the link probability between two adjacent SUs. Third, we investigate the path connectivity between two arbitrary SUs by using the simulation analysis approach. The correctness of our mathematical expressions is confirmed by comparing analytical results with simulation results. The results in this paper provide insights into how multiple communication pairs in primary network affect the connectivity of secondary network, which can be useful guidelines for the design of CRAHNs.

scholarly journals Performance Evaluation of Relay Selection Schemes in Beacon-Assisted Dual-hop Cognitive Radio Wireless Sensor Networks under Impact of Hardware Noises

2018 ◽  
Author(s):  
Tran Dinh Hieu ◽  
Tran Trung Duy ◽  
Le The Dung ◽  
Seong Gon Choi
Keyword(s):  
Wireless Sensor Networks ◽  
Performance Evaluation ◽  
Cognitive Radio ◽  
Sensor Networks ◽  
Relay Selection ◽  
Wireless Sensor ◽  
Secondary Source ◽  
Source Information ◽  
Opportunistic Relay Selection ◽  
The Impact

To solve the problem of energy constraint 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 exact and asymptotic closed-form expressions of outage probability (OP) and throughput (TP) to provide significant insights into the impact of our proposed protocols on the system performance over Rayleigh fading channel. Finally, simulation results validate the theoretical results.

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