scholarly journals Security Analysis of Multi-Antenna NOMA Networks Under I/Q Imbalance

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1327 ◽  
Author(s):  
Xingwang Li ◽  
Mengle Zhao ◽  
Changsen Zhang ◽  
Wali Ullah Khan ◽  
Jun Wu ◽  
...  
Keyword(s):  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Security Analysis ◽  
Base Station ◽  
Selection Combining ◽  
High Signal ◽  
Asymptotic Results ◽  
Intercept Probability ◽  
Outage Probabilities ◽  
Analytical Expressions

This paper investigates the reliability and security performance of the downlink non-orthogonal multiple access (NOMA) networks over Nakagami-m fading channels, where the base station (BS) aims to communicate with multi-antenna NOMA users in the presence of a multi-antenna eavesdropper. To be more practical, a detrimental factor at both transmitter and receiver is considered, namely in-phase and quadrature-phase imbalance (IQI). To further improve the reliability and security of the considered networks, the selection combining (SC) algorithm at the receiver is taken into account. More specifically, the exact analytical expressions for the outage probability (OP) and the intercept probability (IP) are derived in closed-form. To obtain a better understanding of the influence for the IQI parameters on the system performance, the asymptotic behaviors for the outage probabilities (OPs) in the high signal-to-noise ratio (SNR) region are analyzed. Based on the asymptotic results, the diversity order of the considered system are obtained and discussed. The numerical results are presented to verify the validity of the theoretical analysis.

scholarly journals Security-Reliability Tradeoff Analysis in Multisource Multirelay Cooperative Networks with Multiple Cochannel Interferers

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Weilong Hu ◽  
Jiangbo Si ◽  
Hongyan Li
Keyword(s):  
Fading Channels ◽  
Physical Layer Security ◽  
Communication Technologies ◽  
Cooperative Networks ◽  
Cooperative Relaying ◽  
Green Communication ◽  
Intercept Probability ◽  
Outage Probabilities ◽  
Reliability Performance ◽  
The Impact

Cooperative relaying communication is one of the green communication technologies since it shortens the communication distance and saves the transmit power. In this paper, the physical-layer security (PLS) of a multisource multirelay cooperative relaying communication network is investigated by considering the influence of cochannel interference from a security-reliability tradeoff (SRT) perspective. First, the SRT performance is characterized by the outage probability (OP) and the intercept probability (IP). In particular, the IP encountered at the eavesdropper is used to evaluate the security performance, while the reliability performance is analyzed in terms of the OP experienced at the destination. Then, under the impact of multiple cochannel interferers, the intercept probabilities and the outage probabilities of both the conventional direct transmission (DT) strategy and relay selection (RS) strategy are derived in closed-form expressions over Rayleigh fading channels, respectively. Simulation results are provided to validate the theoretical analysis. It is shown that when the OP (reliability) requirement is relaxed, the IP (security) performance improves and vice versa. It confirms that there is an SRT existing between the OP and the IP. Meanwhile, a better SRT performance can be achieved by increasing the number of sources, relays, and cochannel interferers. In addition, it is also shown that the RS strategy generally outperforms the conventional DT strategy in terms of the product of the IP and the OP.

scholarly journals MmWave V2X Cooperative Diversity Relay Channel with Feedback Delay and Link Blockage

2021 ◽  
Author(s):  
Elyes Balti
Keyword(s):  
Cooperative Diversity ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Maximal Ratio Combining ◽  
High Signal ◽  
Relay Channel ◽  
Framework Analysis ◽  
Decode And Forward ◽  
Multiple Transmit ◽  
To Receive

In this work, we present a framework analysis of a millimeter wave (mmWave) vehicular communications systems. Communications between vehicles take place through a cooperative relay which acts as an intermediary base station (BS). The relay is equipped with multiple transmit and receive antennas and it employs decode-and-forward (DF) to process the signal. Also, the relay applies maximal ratio combining (MRC), and maximal ratio transmission (MRT), respectively, to receive and forward the signal.As the vehicles' speeds are relative high, the channel experiences a fast fading and this time variation is modeled following the Jake's autocorrelation model. We also assume narrowband fading channel. Closed-form expressions of the reliability metrics such as the outage probability and the mean rate are derived. Capitalizing on these performances, we derive the high signal-to-noise-ratio (SNR) asymptotes to get full insights into the system gains such as the diversity and coding gains.

scholarly journals Performance Analysis of Rate Splitting in Massive MIMO Systems with Low Resolution ADCs/DACs

2021 ◽  
Vol 11 (20) ◽  
pp. 9409
Author(s):  
Roger Kwao Ahiadormey ◽  
Kwonhue Choi
Keyword(s):  
Mimo Systems ◽  
Mimo System ◽  
Signal To Noise Ratio ◽  
Multiple Input Multiple Output ◽  
Base Station ◽  
Quantization Noise ◽  
High Signal ◽  
Low Resolution ◽  
Rate Splitting ◽  
Noise Ratio

In this paper, we propose rate-splitting (RS) multiple access to mitigate the effects of quantization noise (QN) inherent in low-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). We consider the downlink (DL) of a multiuser massive multiple-input multiple-output (MIMO) system where the base station (BS) is equipped with low-resolution ADCs/DACs. The BS employs the RS scheme for data transmission. Under imperfect channel state information (CSI), we characterize the spectral efficiency (SE) and energy efficiency (EE) by deriving the asymptotic signal-to-interference-and-noise ratio (SINR). For 1-bit resolution, the QN is very high, and the RS scheme shows no rate gain over the non-RS scheme. As the ADC/DAC resolution increases (i.e., 2–3 bits), the RS scheme achieves higher SE in the high signal-to-noise ratio (SNR) regime compared to that of the non-RS scheme. For a 3-bit resolution, the number of antennas can be reduced by 27% in the RS scheme to achieve the same SE as the non-RS scheme. Low-resolution DACs degrades the system performance more than low-resolution ADCs. Hence, it is preferable to equip the system with low-resolution ADCs than low-resolution DACs. The system achieves the best SE/EE tradeoff for 4-bit resolution ADCs/DACs.

scholarly journals Analysis and Design of SCMA-Based Hybrid Unicast-Multicast Relay-Assisted Networks

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 329 ◽  
Author(s):  
Yibo Zhang ◽  
Xiaoxiang Wang ◽  
Dongyu Wang ◽  
Yufang Zhang ◽  
Yanwen Lan
Keyword(s):  
Outage Probability ◽  
Cooperative Diversity ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Cooperative Transmission ◽  
High Signal ◽  
Transmission Scheme ◽  
Two Stage ◽  
Analysis And Design ◽  
Relay Location

This paper studies a multi-user network model based on sparse code multiple access (SCMA), where both unicast and multicast services are considered. In the direct transmission scheme, the communication between the base station (BS) and the users is completed with one stage, in which the relay is inexistent. In the two-stage cooperative transmission scheme, any number of relays are placed to improve the reliability of wireless communication system. The BS broadcasts the requested message to users and relays in the first stage, and the successful relays forward the message to unsuccessful users in the second stage. To characterize the performance of these two schemes, we derive the exact and approximate expressions of average outage probability. Furthermore, to take full advantage of the cooperative diversity, an optimal power allocation and relay location strategy in the high signal-to-noise ratio (SNR) regime is studied. The outage probability reaches the minimum value when the first stage occupies half of the total energy consumed. Simulation and analysis results are presented to demonstrate the performance of these two schemes. The results show that the two-stage cooperative scheme effectively reduce the average outage probability in SCMA network, especially in the high SNR region.

scholarly journals On the Performance Balancing for Uplink NOMA Systems

2020 ◽  
Vol 13 (6) ◽  
pp. 454-459
Author(s):  
Nam-Soo Kim ◽  
Keyword(s):  
Outage Probability ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Base Station ◽  
Cellular Systems ◽  
Mobile Cellular ◽  
Noise Ratio ◽  
Outage Probabilities ◽  
Error Floors

Outage probability and capacity are the representative performance measures for the quality of service (QoS) in mobile cellular systems. Recently, power back-off scheme is proposed in uplink non-orthogonal multiple access (NOMA) systems. The power back-off scheme improves the performance of a near user, however, decreases that of a far user. In comparison, the scheme indicates the error floors with an outage probability of 2.4×〖10〗^(-1) and 9.1×〖10〗^(-2) with power back-off 5 dB and 10 dB, respectively under the specified condition. To address these drawbacks, we propose an equal average signal-to–interference plus noise ratio (SINR) scheme that derives the same average SINR from active users at the base station (BS) in uplink non-orthogonal multiple access (NOMA) systems. Numerical results show that required signal-to-noise ratio (SNR) for the outage probability of 1×〖10〗^(-3) of the near and far users are close enough within 1 dB, which means an outage balance between two users. And it is noticed that the outage probabilities in the proposed scheme decrease as the increase of the received SNR without error floors. Also, different from the power back-off scheme, we noticed that the capacities of the two users in the proposed scheme are coincident and increase with SNR. The outage probabilities and ergodic capacity of the near and far users are derived in closed-form expressions. The analytical results are conformed by Monte Carlo simulation.

scholarly journals System Performance of Cooperative NOMA with Full-Duplex Relay over Nakagami-m Fading Channels

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xuan-Xinh Nguyen ◽  
Dinh-Thuan Do
Keyword(s):  
Fading Channels ◽  
System Performance ◽  
Multiple Access ◽  
Base Station ◽  
Full Duplex ◽  
Decode And Forward ◽  
Relay Systems ◽  
Channel Environment ◽  
Analytical Expressions ◽  
Dual User

In this paper, we consider a dual-user nonorthogonal multiple access (NOMA) with the help of full-duplex decode-and-forward (DF) relay systems with respect to Nakagami-m fading channel environment. Especially, we derive the analytical expressions to evaluate system performance in terms of outage probability, achievable throughput, and energy efficiency. The main investigation is on considering how the fading parameters and transmitting power at the base station make crucial impacts on system performance in the various scenarios. Finally, simulations are conducted to confirm the validity of the analysis and show the system performance of NOMA under different fading parameters of Nakagami-m fading channels.

A COMPARITIVE STUDY OF W-CDMA CELL SEARCH DESIGNS

2005 ◽  
Vol 14 (01) ◽  
pp. 129-135 ◽  
Author(s):  
SANAT KAMAL BAHL ◽  
JIM PLUSQUELLIC ◽  
JOSEPH THOMAS
Keyword(s):  
Cyclic Codes ◽  
Signal To Noise Ratio ◽  
Additive White Gaussian Noise ◽  
Base Station ◽  
Acquisition Time ◽  
High Signal ◽  
Cell Search ◽  
Field Programmable ◽  
Search Designs ◽  
Search Design

In this letter an Improved Cell Search Design using cyclic codes (Improved CSD) is compared with the 3GPP Cell Search Design using comma free codes (3GPP-comma free CSD) in terms of (1) hardware utilization on a field programmable gate array and (2) acquisition time measures for different probabilities of false alarm rates. Our results indicate that for an additive white Gaussian noise channel in a high signal-to-noise ratio the Improved CSD achieves faster synchronization with the base station and has lower hardware utilization when compared with the 3GPP-comma free CSD scheme under the same design constraints.

Large Intelligent Surfaces Communicating Through Massive MIMO Rayleigh Fading Channels

2020 ◽  
Author(s):  
Ricardo Coelho Ferreira ◽  
Michelle S. P. Facina ◽  
Felipe A. P. de Figueiredo ◽  
Gustavo Fraidenraich ◽  
Eduardo Rodrigues de Lima
Keyword(s):  
Antenna Array ◽  
Fading Channels ◽  
Gamma Distribution ◽  
Signal To Noise Ratio ◽  
Phase Error ◽  
Base Station ◽  
Channel Fading ◽  
Phase Cancellation ◽  
Analytical Approximations ◽  
Single User

Large intelligent surfaces (LIS) promises not only to improve the signal to noise ratio, and spectral efficiency but also to reduce the energy consumption during the transmission. We consider a base station equipped with an antenna array using the maximum ratio transmission (MRT), and a large reflector array sending signals to a single user. Each subchannel is affected by the Rayleigh flat fading, and the reflecting elements perform non-perfect phase correction which introduces a Von Mises distributed phase error. Based on the central limit theorem (CLT), we conclude that the overall channel has an equivalent Gamma fading whose parameters are derived from the moments of the channel fading between the antenna array and LIS, and also from the LIS to the single user. Assuming that the equivalent channel can be modeled as a Gamma distribution, we propose very accurate closed-form expressions for the bit error probability and a very tight upper bound. For the case where the LIS is not able to perform perfect phase cancellation, that is, under phase errors, it is possible to analyze the system performance considering the analytical approximations and the simulated results obtained using the well known Monte Carlo method. The analytical expressions for the parameters of the Gamma distribution are very difficult to be obtained due to the complexity of the nonlinear transformations of random variables with non-zero mean and correlated terms. Even with perfect phase cancellation, all the fading coefficients are complex due to the link between the user and the base station that is not neglected in this paper.

scholarly journals A Comparative Study of Relaying Schemes with Decode and Forward over Nakagami- Fading Channels

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
George C. Alexandropoulos ◽  
Agisilaos Papadogiannis ◽  
Paschalis C. Sofotasios
Keyword(s):  
Closed Form ◽  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Wireless Systems ◽  
Nakagami Fading ◽  
Decode And Forward ◽  
Channel State ◽  
Modulation Methods ◽  
Nakagami Fading Channels ◽  
Analytical Expressions

Although relaying can be very beneficial for wireless systems, understanding which relaying schemes can achieve specific performance objectives under realistic fading is crucial. In this paper we present a general framework for modeling and evaluating the performance of dual-hop decode-and-forward (DF) relaying schemes over independent and not necessarily identically distributed (INID) Nakagami- fading channels. We obtain closed-form expressions for the statistics of the instantaneous output signal-to-noise ratio of repetitive transmission with selection diversity. Furthermore, we present a unified statistical overview of other three significant relaying schemes with DF, one based on repetitive transmission with maximal-ratio diversity and the other two based on relay selection (RS). To compare the considered schemes, we present closed-form and analytical expressions for the outage probability and the average symbol error probability under various modulation methods, respectively. Importantly, it is shown that when the channel state information for RS is perfect, RS-based schemes always outperform repetitive ones. Furthermore, when the direct link between the source and the destination nodes is sufficiently strong, relaying may not result in any gains, and it should be switched off.

scholarly journals Exact secure outage probability performance of uplinkdownlink multiple access network under imperfect CSI

2021 ◽  
Vol 10 (6) ◽  
pp. 3274-3281
Author(s):  
Dinh-Thuan Do ◽  
Minh-Sang Van Nguyen
Keyword(s):  
Outage Probability ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Access Network ◽  
Base Station ◽  
High Signal ◽  
Secrecy Outage Probability ◽  
Factors Affecting ◽  
Secrecy Outage ◽  
The Right

In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.

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