scholarly journals Approximation of Capacity for Downlink Multi-User System with Combination of Precoding and NOMA Methods

2021 ◽  
Vol 11 (22) ◽  
pp. 10578
Author(s):  
Vu Van Son ◽  
Nguyen Le Cuong ◽  
Nguyen Thu Phuong ◽  
Tran Manh Hoang ◽  
Pham Thanh Hiep
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Wireless Systems ◽  
Ergodic Capacity ◽  
Closed Form Expression ◽  
Important Research ◽  
Analysis Method ◽  
Form Expression ◽  
Access Method ◽  
Novel Method

Enhancing performance of downlink MU systems is an attractive and important research for future wireless systems. The non-orthogonal multiple access (NOMA) method was proposed to improve the performance of MU systems. In order to further improve the outage probability (OP) and ergodic capacity (EC) of downlink NOMA MU systems, we propose the combination of precoding and NOMA methods, and then the OP and EC of MU systems with our novel method are derived in scenarios of perfect and imperfect successive interference cancellation (SIC) scheme. Moreover, the closed-form expression of OP and EC for both scenarios is theoretically derived and compared with Monte Carlo simulations. The results show that, the analysis method is accurate, and the proposed combining precoding and NOMA can further enhance the performance of MU systems in comparing with the original orthogonal multiple access method.

Approximate closed-form expression for the ergodic capacity of polarisation-diversity MIMO systems

2004 ◽  
Vol 40 (19) ◽  
pp. 1192 ◽  
Author(s):  
J. Pérez ◽  
J. Ibáñez ◽  
L. Vielva ◽  
I. Santamaría
Keyword(s):  
Closed Form ◽  
Mimo Systems ◽  
Ergodic Capacity ◽  
Closed Form Expression ◽  
Form Expression

Outage Performance Analysis for User Cooperative NOMA with Incremental Hybrid Forwarding Protocols

2021 ◽  
Author(s):  
Suyue Li ◽  
Junhuai Liu ◽  
Anhong Wang
Keyword(s):  
Monte Carlo ◽  
Outage Probability ◽  
Multiple Access ◽  
System Throughput ◽  
Closed Form Expression ◽  
Collaborative Communication ◽  
Form Expression ◽  
Outage Performance ◽  
Threshold Rate ◽  
Rate Pair

Abstract Non-orthogonal multiple access (NOMA) collaborative communication is extremely beneficial to the users with poor channel conditions. It is essential to examine the performance of different NOMA users with superior cooperative forwarding protocols. This paper addresses the user cooperative NOMA system where one strong user (U2) assists one weak user (U1) to forward messages, and investigates the outage performance of both users with hybrid decode-and-amplify forwarding (HDAF) protocol. First, we derive the outage probability of U2 and U1 with HDAF. Secondly, we provide the closed-form expression for outage probability of U1 with the incremental hybrid decode-and-amplify forward (IHDAF) protocol at U2, which can further enhance the outage performance of U1 compared with HDAF. Moreover, we also present the system throughput expression and provide deep analysis on the effect of different forwarding protocols. Numerical results and Monte Carlo simulations jointly confirm the correctness of all the analytic derivations. In addition to saving the energy consumption of U2, IHDAF can make U1 achieve superior outage performance to HDAF. However, the system throughput almost overlap for both schemes given a threshold rate pair.

scholarly journals Capacity Analysis of Distributed Antenna Systems with Multiple Receive Antennas over MIMO Fading Channel

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Xiangbin Yu ◽  
Xiaoshuai Liu ◽  
Yuyu Xin ◽  
Ming Chen ◽  
Yun Rui
Keyword(s):  
Closed Form ◽  
Approximate Expression ◽  
Ergodic Capacity ◽  
Moment Generating Function ◽  
Closed Form Expression ◽  
Outage Capacity ◽  
Form Expression ◽  
Distributed Antenna Systems ◽  
Distributed Antenna ◽  
Antenna Systems

The downlink performance and capacity of distributed antenna systems (DASs) with multiple receive antennas are investigated in multi-input multi-output (MIMO) fading and multicell environment. Based on the moment generating function and performance analysis, an exact closed-form expression of DAS ergodic capacity is derived, and it includes the existing capacity expression as a special case. Moreover, a simple closed-form approximate expression of ergodic capacity is also derived by using the Taylor series, and it has the performance result close to the exact expression. Besides, the outage capacity of DAS is analyzed, and an exact closed-form expression of outage capacity probability is derived. All these expressions can provide good theoretical performance evaluation for DAS. Simulation results corroborate our theoretical analysis.

Determination of Constant Orientation Workspace of a Stewart Platform by Geometrical Method

2015 ◽  
Vol 813-814 ◽  
pp. 997-1001 ◽  
Author(s):  
S. Gokul Narasimhan ◽  
R. Shrivatsan ◽  
K. Venkatasubramanian ◽  
Anjan Kumar Dash
Keyword(s):  
Algebraic Method ◽  
Parallel Manipulators ◽  
Stewart Platform ◽  
Closed Form Expression ◽  
Robot Design ◽  
Form Expression ◽  
Novel Method ◽  
Workspace Optimization ◽  
Orientation Workspace

Determination of workspace is one of the main considerations in the design of any robot since the workspace geometry is considered a fundamental issue for robot design. This also plays a crucial role in trajectory planning. Among parallel manipulators, 6-DOF Stewart platforms is the most researched and widely used robot. However, till date there is no closed form expression of workspace volume for Stewart platform. In this paper, a novel method is proposed to find out the workspace volume of Stewart platform. In this paper, individual workspace of each leg of the manipulator (P-U-S) is determined and then translated by a common distance towards their geometrical center thus generating constant orientation workspace. To determine the workspace volume, geometric intersection of the six spheres is computed. This results in workspace of definite shape and size, whose volume is calculated using simple formulae. It is observed that the geometric way of determination of workspace area is computationally less tedious than the algebraic method. This also helps a lot for workspace optimization of such manipulators.

scholarly journals On Throughput for UAV Relay Assisted for Use in Disaster Communications

2021 ◽  
Author(s):  
Van Vo Nhan ◽  
Dang Ngoc Cuong ◽  
Tran Ban Thach ◽  
Hung Tran
Keyword(s):  
System Performance ◽  
Multiple Access ◽  
Base Station ◽  
Closed Form Expression ◽  
Second Phase ◽  
Form Expression ◽  
Decode And Forward ◽  
Disaster Communications ◽  
Aerial Vehicle ◽  
Two Phases

In this paper, the system performance of an energy harvesting (EH) unmanned aerial vehicle (UAV) system for use in disasters was investigated. The communication protocol was divided into two phases. In the first phase, a UAV relay (UR) harvested energy from a power beacon (PB). In the second phase, a base station (BS) transmitted the signal to the UR using non-orthogonal multiple access (NOMA); then, the UR used its harvested energy from the first phase to transfer the signal to two sensor clusters, i.e., low-priority and high-priority clusters, via the decode-and-forward (DF) technique. A closed-form expression for the throughput of the cluster heads of these clusters was derived to analyze the system performance. Monte Carlo simulations were employed to verify our approach.

Exact Ergodic Capacity Analysis for Cognitive Underlay Amplify-and-Forward Relay Networks over Rayleigh Fading Channels

2017 ◽  
Author(s):  
Vo Nguyen Quoc Bao ◽  
Vu Van San
Keyword(s):  
Fading Channels ◽  
Rayleigh Fading ◽  
Relay Networks ◽  
Ergodic Capacity ◽  
Closed Form Expression ◽  
Rayleigh Fading Channels ◽  
Capacity Analysis ◽  
Amplify And Forward ◽  
Form Expression ◽  
Decode And Forward

In this paper, we propose a novel derivation approach to obtain the exact closed form expression of ergodic capacity for cognitive underlay amplify-and-forward (AF) relay networks over Rayleigh fading channels. Simulation results are performed to verify the analysis results. Numerical results are provided to compare the system performance of cognitive underlay amplify-and-forward relay networks under both cases of AF and decode-and-forward (DF) confirming that the system with DF provides better performance as compared with that with AF. DOI: 10.32913/rd-ict.vol3.no14.563

scholarly journals Uplink IoT Networks: Time-Division Priority-Based Non-Orthogonal Multiple Access Approach

2021 ◽  
Author(s):  
Basem M. Elhalawany ◽  
Ahmad A.Aziz El-Banna ◽  
Kaishun Wu ◽  
Wali Ullah Khan
Keyword(s):  
Power Allocation ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Transmission Time ◽  
Limited Power ◽  
Iot Devices ◽  
Time Division

Non-orthogonal multiple access (NOMA) has been investigated to support massive connectivity for Internet-of-things (IoT) networks. However, since most IoT devices suffer from limited power and decoding capabilities, it is not desirable to pair a large number of devices simultaneously, which encourages two-user NOMA grouping. Additionally, most existing techniques have not considered the diversity in the target QoS of IoT devices, which may lead to spectrum inefficiency. Few investigations have partially considered that issue by using an order-based power allocation (OPA) approach, where the power is allocated according to the order to the user's target throughput within a priority-based NOMA (PNOMA) group. However, this does not fully capture the effects of diversity in the values of the users' target throughputs. In this work, we handle both problems by considering a throughput-based power allocation (TPA) approach, that captures the QoS diversity, within a three-users PNOMA group as a compromise between spectral efficiency and complexity. Specifically, we investigate the performance of a time-division PNOMA (TD-PNOMA) scheme, where the transmission time is divided into two-time slots with two-users per PNOMA group. The performance of such TD-PNOMA is compared with a fully PNOMA (F-PNOMA) scheme, where the three users share the whole transmission time, in terms of the ergodic capacity under imperfect successive interference cancellation (SIC). The results reveal the superiority of TPA compared with OPA approach in both schemes, besides that the throughput of both schemes can outperform each other under imperfect SIC based on the transmit signal-to-noise ratio and the deployment scenarios.

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