scholarly journals Performance Analysis of MEC Based on NOMA under Imperfect CSI with Eavesdropper

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xuehua Li ◽  
Yingjie Pei ◽  
Huan Jiang ◽  
Xinwei Yue ◽  
Yafei Wang ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Channel State Information ◽  
Multiple Access ◽  
System Throughput ◽  
Secrecy Outage Probability ◽  
Imperfect Csi ◽  
Channel State ◽  
State Information ◽  
Secrecy Outage ◽  
The Impact

Mobile edge computing (MEC) is becoming more and more popular because of improving computing power in virtual reality, augmented reality, unmanned driving, and other fields. This paper investigates a nonorthogonal multiple access- (NOMA-) based MEC system, which is under imperfect channel state information (ipCSI). In this system model, a pair of users offloads their tasks to the MEC server with the existence of an eavesdropper (Eve). To evaluate the impact of Eve on the performance of the NOMA-MEC system, the secrecy outage probability (SOP) expressions for two users with the conditions of imperfect CSI and perfect channel state information (pCSI) are derived. In addition, both throughput and energy efficiency are discussed in the delay-limited transmission mode. Simulation results reveal that (1) due to the influence of channel estimation errors, the secrecy outage behaviors of two users under ipCSI conditions are worse than those of users with pCSI; (2) the secrecy performance of NOMA-MEC is superior to orthogonal multiple access- (OMA-) aided MEC systems; and (3) the NOMA-MEC systems have the ability to attain better system throughput and energy efficiency compared with OMA-MEC.

scholarly journals Secrecy Outage Probability of a NOMA Scheme and Impact Imperfect Channel State Information in Underlay Cooperative Cognitive Networks

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 895
Author(s):  
Tan-Phuoc Huynh ◽  
Duy-Hung Ha ◽  
Cong Truong Thanh ◽  
Peppino Fazio ◽  
Miroslav Voznak
Keyword(s):  
Fading Channels ◽  
Channel State Information ◽  
Cognitive Networks ◽  
Source Node ◽  
Secrecy Outage Probability ◽  
Imperfect Channel State Information ◽  
Channel State ◽  
State Information ◽  
Secrecy Outage ◽  
The Impact

Security performance and the impact of imperfect channel state information (CSI) in underlay cooperative cognitive networks (UCCN) is investigated in this paper. In the proposed scheme, relay R uses non-orthogonal multiple access (NOMA) technology to transfer messages e 1 , e 2 from the source node S to User 1 (U1) and User 2 (U2), respectively. An eavesdropper (E) is also proposed to wiretap the messages of U1 and U2. The transmission’s security performance in the proposed system was analyzed and performed over Rayleigh fading channels. Through numerical analysis, the results showed that the proposed system’s secrecy performance became more efficient when the eavesdropper node E was farther away from the source node S and the intermediate cooperative relay R. The secrecy performance of U1 was also compared to the secrecy performance of U2. Finally, the simulation results matched the Monte Carlo simulations well.

scholarly journals A Joint Optimization Scheme of Resource Allocation in Downlink NOMA with Statistical Channel State Information

2020 ◽  
Author(s):  
Lei Xu ◽  
Jing Yi Yao ◽  
Jing Cai ◽  
Yu Hong Fang ◽  
Hui Xiao Li
Keyword(s):  
Power Allocation ◽  
Channel State Information ◽  
Communication Systems ◽  
Multiple Access ◽  
Joint Optimization ◽  
System Throughput ◽  
Optimization Scheme ◽  
Channel State ◽  
State Information ◽  
User Grouping

Abstract In a real communication scenario, it is very difficult to obtain the real-time Channel State Information(CSI) accurately, so the communication systems with statistical CSI have been researched. In order to maximize the throughput of the downlink Non-Orthogonal Multiple Access (NOMA) system with statistical CSI, the formula of system throughput is derived at first. Then, according to the combinatorial characteristics of the original optimization problem, it is divided into two subproblems, that is user grouping and power allocation. At last, a joint optimization scheme is proposed. In which, Genetic algorithm is introduced to solve the subproblem of power allocation, and Hungarian algorithm is introduced to solve the subproblem of user grouping. By comparing the ergodic date rate of NOMA users with statistical CSI and perfect CSI, the effectiveness of the statistical CSI sorting is verified. Compared with the Orthogonal Multiple Access (OMA) scheme, the NOMA scheme with the fixed user grouping scheme and the random user grouping scheme, the proposed scheme can effectively improve the system throughput.

scholarly journals CR-NOMA Networks over Nakagami- m Fading: CSI Imperfection Perspective

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Anh-Tu Le ◽  
Dinh-Thuan Do
Keyword(s):  
Fading Channel ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
Imperfect Csi ◽  
Throughput Performance ◽  
Channel State ◽  
State Information ◽  
Perfect Channel State Information ◽  
Secondary Network ◽  
The Impact

There are high demands on both massive connections and high spectrum efficiency, and the cognitive radio-based nonorthogonal multiple access (CR-NOMA) system is developed to satisfy such demand. The unreal situation of CR-NOMA is considering the perfect channel state information (CSI) in receivers. This paper indicates impacts of imperfect CSI on outage and throughput performance. In particular, we focus on performance of the secondary network related to the imperfect CSI, and we derive closed-form expressions of outage probability and throughput for the downlink in such a CR-NOMA system. Particularly, a general form of Nakagami- m fading channel is adopted to examine the impact of fading on the performance of the CR-NOMA system. As the main achievement, we conduct extensive simulations and provide analyses to demonstrate the outage performance of the CR-NOMA system with CSI imperfections.

scholarly journals On Secrecy Outage Probability for Downlink NOMA Systems With Relay-Antenna Selection

2021 ◽  
Author(s):  
Shu Xu ◽  
Chen Liu ◽  
Hong Wang ◽  
Mujun Qian ◽  
Wenfeng Sun
Keyword(s):  
Outage Probability ◽  
Multiple Access ◽  
Antenna Selection ◽  
Maximal Ratio Combining ◽  
Selection Combining ◽  
Secrecy Outage Probability ◽  
Channel State ◽  
Secrecy Outage ◽  
Secure Transmission ◽  
Theoretical Results

Abstract Secure transmission is essential for future non-orthogonal multiple access (NOMA) system. This paper investigates relay-antenna selection (RAS) to enhance physical-layer security (PLS) of cooperative NOMA system in the presence of an eavesdropper, where multiple antennas are deployed at the relays, the users, and the eavesdropper. In order to reduce expense on radio frequency (RF) chains, selection combining (SC) is employed at both the relays and the users, whilst the eavesdropper employs either maximal-ratio combining (MRC) or selection combining (SC) to process the received signals. Under the condition that the channel state information (CSI) of the eavesdropping channel is available or unavailable, two e↵ective relay-antenna selection schemes are proposed. Additionally, the closed-form expressions of secrecy outage probability (SOP) are derived for the proposed relay-antenna selection schemes. In order to gain more deep insights on the derived results, the asymptotic performance of the derived SOP is analyzed. In simulations, it is demonstrated that the theoretical results match well with the simulation results and the SOP of the proposed schemes is less than that of the conventional orthogonal multiple access (OMA) scheme obviously.

scholarly journals On the Performance of Battery-Assisted PS-SWIPT Enabled DF Relaying

Information ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 165 ◽  
Author(s):  
Zhipeng Liu ◽  
Guangyue Lu ◽  
Yinghui Ye ◽  
Liqin Shi
Keyword(s):  
Energy Efficiency ◽  
Computer Simulations ◽  
Channel State Information ◽  
Power Splitting ◽  
Power Transfer ◽  
Decode And Forward ◽  
Channel State ◽  
Relay System ◽  
State Information ◽  
Analytical Results

Compared with the conventional simultaneous wireless information and power transfer (SWIPT) based relaying with “harvest-then-forward” protocol, the battery-assisted SWIPT relaying is more practical and powerful due to the joint use of the harvested energy and supplementary battery. However, to the best of our knowledge, the performance of a battery-assisted power splitting (PS)-SWIPT decode-and-forward (DF) relay system has not been studied. In this paper, for a given amount of energy from the relay’s battery, we propose to maximize the outage and ergodic capacities by optimizing the static and dynamic PS ratios that rely on statistical and instantaneous channel state information (CSI), respectively, and derive their corresponding outage and ergodic capacities. Computer simulations validate our analytical results and demonstrate the advantages of the dynamic PS over the static PS in terms of the outage and ergodic capacities, as well as the energy efficiency.

scholarly journals Channel and Bit Adaptive Power Control Strategy for Uplink NOMA VLC Systems

2019 ◽  
Vol 9 (2) ◽  
pp. 220 ◽  
Author(s):  
Zhen-Yu Wang ◽  
Hong-Yi Yu ◽  
Da-Ming Wang
Keyword(s):  
Power Control ◽  
Power Allocation ◽  
Channel State Information ◽  
Control Strategy ◽  
Multiple Access ◽  
Visible Light Communication ◽  
Allocation Scheme ◽  
Channel State ◽  
State Information ◽  
Adaptive Power

Non-orthogonal multiple access (NOMA) can be an effective solution to the limited bandwidth of light emitting diodes for visible light communication (VLC) systems to support multiuser communication. The current available works for NOMA VLC systems mainly concentrate on downlinks and the existing power allocation algorithms mainly focus on the channel state information and ignore the influence of transmitted signals. In this paper, we propose a channel and bit adaptive power control strategy for uplink NOMA VLC systems by jointly considering the channel state information and the transmission bit rate. Under this adaptive power control strategy, it is proved that the received signal at the photodiode (PD) receiver constitutes a sizeable pulse amplitude modulation constellation and low-complexity maximum likelihood detection is admitted. The simulation results indicate that our proposed adaptive power control strategy outperforms the gain ratio power allocation scheme, fixed power allocation scheme, and time division multiple access scheme.

Non‐orthogonal multiple access without channel state information for similar channel conditions

2019 ◽  
Vol 55 (8) ◽  
pp. 493-495 ◽  
Author(s):  
Wenlong Xia ◽  
Qingdang Meng ◽  
Qingchuan Tao ◽  
Ray T. Chen
Keyword(s):  
Channel State Information ◽  
Multiple Access ◽  
Channel State ◽  
State Information ◽  
Channel Conditions
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