scholarly journals A new look on CSI imperfection in downlink NOMA systems

2021 ◽  
Vol 10 (3) ◽  
pp. 1415-1422
Author(s):  
Anh-Tu Le ◽  
Dinh-Thuan Do
Keyword(s):  
Monte Carlo ◽  
Performance Analysis ◽  
System Performance ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
System Model ◽  
Full Duplex ◽  
Channel State ◽  
State Information ◽  
Cooperative Scheme

Observing that cooperative scheme benefits to non-orthogonal multiple access (NOMA) systems, we focus on system performance analysis of downlink. However, spectrum efficiency is still high priority to be addressed in existing systems and hence this paper presents full-duplex enabling in NOMA systems. Other challenge needs be considered related to channel state information (CSI). In particular, we derive closedform expressions of outage probability for such NOMA systems under the presence of CSI imperfection. Furthermore, to fully exploit practical environment, we provide system model associated with Nakagami-m fading. The Monte-Carlo simulations are conducted to verify the exactness of considered systems.

scholarly journals Impacts of Imperfect Channel State Information, Transceiver Hardware, and Self-Interference Cancellation on the Performance of Full-Duplex MIMO Relay System

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1671 ◽  
Author(s):  
Ba Cao Nguyen ◽  
Nguyen Nhu Thang ◽  
Xuan Nam Tran ◽  
Le The Dung
Keyword(s):  
System Performance ◽  
Interference Cancellation ◽  
Estimation Error ◽  
Full Duplex ◽  
Channel Estimation Error ◽  
Imperfect Channel State Information ◽  
Channel State ◽  
Relay System ◽  
State Information ◽  
Mimo Relay

Imperfect channel state information (I-CSI) and imperfect transceiver hardware often happen in wireless communication systems due to the time-varying and random characteristics of both wireless channels and hardware components. The impacts of I-CSI and hardware impairments (HI) reduce not only the system performance but also the self-interference cancellation (SIC) capability of full-duplex (FD) devices. To investigate the system performance in realistic scenarios, in this paper, we consider the performance of an FD multiple-input multiple-output (MIMO) relay system under the effects of I-CSI, imperfect SIC (I-SIC), and imperfect transceiver hardware. We mathematically derive the exact closed-form expressions of the outage probability (OP) and ergodic capacity of the considered HI-FD-MIMO relay system over Rayleigh fading channels with the existence of I-CSI, I-SIC, and HI. Numerical results indicate that the performance in terms of OP and capacity reaches saturation faster, especially when the channel estimation error, the residual self-interference (RSI), and HI levels are remarkable. Therefore, various solutions for effectively reducing the channel estimation error, RSI, and HI levels in the HI-FD-MIMO relay system should be carried out to improve the system performance. All derived mathematical expressions are verified through Monte-Carlo simulations.

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 Full-Duplex Relay with Delayed CSI Elevates the SDoF of the MIMO X Channel

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1484
Author(s):  
Tong Zhang ◽  
Gaojie Chen ◽  
Shuai Wang ◽  
Rui Wang
Keyword(s):  
Lower Bound ◽  
Channel State Information ◽  
Interference Alignment ◽  
Upper Bounds ◽  
Full Duplex ◽  
Multiple Antenna ◽  
Lower And Upper Bounds ◽  
Channel State ◽  
State Information ◽  
Full Duplex Relay

In this article, the sum secure degrees-of-freedom (SDoF) of the multiple-input multiple-output (MIMO) X channel with confidential messages (XCCM) and arbitrary antenna configurations is studied, where there is no channel state information (CSI) at two transmitters and only delayed CSI at a multiple-antenna, full-duplex, and decode-and-forward relay. We aim at establishing the sum-SDoF lower and upper bounds. For the sum-SDoF lower bound, we design three relay-aided transmission schemes, namely, the relay-aided jamming scheme, the relay-aided jamming and one-receiver interference alignment scheme, and the relay-aided jamming and two-receiver interference alignment scheme, each corresponding to one case of antenna configurations. Moreover, the security and decoding of each scheme are analyzed. The sum-SDoF upper bound is proposed by means of the existing SDoF region of two-user MIMO broadcast channel with confidential messages (BCCM) and delayed channel state information at the transmitter (CSIT). As a result, the sum-SDoF lower and upper bounds are derived, and the sum-SDoF is characterized when the relay has sufficiently large antennas. Furthermore, even assuming no CSI at two transmitters, our results show that a multiple-antenna full-duplex relay with delayed CSI can elevate the sum-SDoF of the MIMO XCCM. This is corroborated by the fact that the derived sum-SDoF lower bound can be greater than the sum-SDoF of the MIMO XCCM with output feedback and delayed CSIT.

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 Performance Improvement on Nonorthogonal Multiple Access without CSIT

2020 ◽  
Vol 2020 ◽  
pp. 1-6 ◽  
Author(s):  
Wenlong Xia ◽  
Yuanping Zhou ◽  
Qingdang Meng
Keyword(s):  
Performance Improvement ◽  
Multiple Access ◽  
Euclidean Distance ◽  
Computational Cost ◽  
Optimal Solution ◽  
The Novel ◽  
Channel State ◽  
State Information ◽  
Virtual Channels ◽  
Constrained Capacity

In this paper, a downlink virtual-channel-optimization nonorthogonal multiple access (VNOMA) without channel state information at the transmitter (CSIT) is proposed. The novel idea is to construct multiple complex virtual channels by jointly adjusting the amplitudes and phases to maximize the minimum Euclidean distance (MED) among the superposed constellation points. The optimal solution is derived in the absence of CSIT. Considering practical communications with finite input constellations in which symbols are uniformly distributed, we resort to the sum constellation constrained capacity (CCC) to evaluate the performance. For MED criterion, the maximum likelihood (ML) decoder is expected at the receiver. To decrease the computational cost, we propose a reduced-complexity bitwise ML (RBML) decoder. Experimental results are presented to validate the superior of our proposed scheme.

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.

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