scholarly journals Joint Power Allocation and Bit-Loading for Multicarrier Systems with Discrete Modulation

2021 ◽  
Vol 8 (4) ◽  
pp. 626-634
Author(s):  
Abdul-Nasser Nofal ◽  
Abdel-Nasser Assimi ◽  
Yasser M. Jaamour
Keyword(s):  
Power Allocation ◽  
Lagrangian Relaxation ◽  
Optimal Solution ◽  
Low Complexity ◽  
Discrete Optimization Problem ◽  
Joint Power ◽  
Multicarrier Systems ◽  
Bit Loading ◽  
Suboptimal Solution ◽  
Lagrangian Relaxation Algorithm

In this paper, we propose two algorithms for joint power allocation and bit-loading in multicarrier systems using discrete modulations. The objective is to maximize the data rate under the constraint of a suitable Bit Error Rate per subcarrier. The first algorithm is based on the Lagrangian Relaxation of the discrete optimization problem in order to find an initial solution. A discrete solution is found by bit truncation followed by an iterative modulation adjustment. The second algorithm is based on Discrete Coordinate Ascent framework with iterative modulation increment of one selected subcarrier at each iteration. A simple cost function related to the power increment per bit is used for subcarrier selection. A sub-optimal low complexity Discrete Coordinate Ascent algorithm is proposed that overcome the limitations of the Hughes-Hartogs algorithm. The Lagrangian Relaxation algorithm provides a suboptimal solution for non-coded system using M-QAM modulations, whereas the low complexity Discrete Coordinate Ascent algorithm provides a near optimal solution for coded as well as for non-coded system using an arbitrary modulation set. Numerical results show the efficiency of the proposed algorithms in comparison with traditional methods.

scholarly journals Resource Allocation and QoS Provisioning for Wireless Relay Networks

2010 ◽  
pp. 125-150 ◽  
Author(s):  
Long Bao Le ◽  
Sergiy A. Vorobyov ◽  
Khoa T. Phan ◽  
Tho Le-Ngoc
Keyword(s):  
Resource Allocation ◽  
Power Allocation ◽  
Cooperative Diversity ◽  
Relay Networks ◽  
Low Complexity ◽  
Qos Provisioning ◽  
Wireless Relay Networks ◽  
Joint Power ◽  
Minimum Rate ◽  
Wireless Relay

This chapter reviews fundamental protocol engineering aspects and presents resource allocation approaches for wireless relay networks. Important cooperative diversity protocols and their typical applications in different wireless network environments are first described. Then, performance analysis and QoS provisioning issues for wireless networks using cooperative diversity are discussed. Finally, resource allocation in wireless relay networks through power allocation for both single and multi-user scenarios are presented. For the multi-user case, we consider relay power allocation under different fairness criteria with or without user minimum rate requirements. When users have minimum rate requirements, we develop a joint power allocation and addmission control algorithm with low-complexity to circumvent the high complexity of the underlying problem. Numerical results are then presented, which illustrate interesting throughput and fairness tradeoff and demonstrate the efficiency of the proposed power control and addmission control algorithms.

scholarly journals Joint Relay Selection and Power Allocation for the Physical Layer Security of Two-Way Cooperative Relaying Networks

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Lei Pan ◽  
Zan Li ◽  
Zhengyuan Wang ◽  
Fenggan Zhang
Keyword(s):  
Power Allocation ◽  
Physical Layer Security ◽  
Relay Selection ◽  
Optimal Solution ◽  
Pso Algorithm ◽  
Low Complexity ◽  
Physical Layer ◽  
Cooperative Relaying ◽  
Amplify And Forward ◽  
Secrecy Rate

In this paper, we investigate the physical layer security of cooperative two-way relay transmission systems using the amplify-and-forward (AF) protocol in the presence of an eavesdropper. A joint relay selection (RS) and power allocation (PA) scheme is proposed to protect the source-destination transmission against the eavesdropper. However, due to the high computational complexity, it is difficult to obtain the optimal solution for the system secrecy rate. Fortunately, an approximate optimal solution by using the particle swarm optimization (PSO) algorithm is derived. In the simulations, we use random relay selection with optimal power allocation (RRS-OPA) and equal power allocation with optimal relay selection (EPA-ORS) as benchmark schemes to verify the effectiveness of the proposed method. The simulation results show that the proposed method outperforms both RRS-OPA and EPA-ORS and significantly improves the system performance with low complexity.

scholarly journals Low-complexity beam-domain channel estimation and power allocation in hybrid architecture massive MIMO systems

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Xiao Chen ◽  
Zaichen Zhang ◽  
Liang Wu ◽  
Jian Dang
Keyword(s):  
Channel Estimation ◽  
Power Allocation ◽  
Spectral Efficiency ◽  
Communication Systems ◽  
Mimo Systems ◽  
Beam Steering ◽  
Estimation Method ◽  
Low Complexity ◽  
Estimation Accuracy ◽  
Hybrid Architecture

Abstract In this journal, we investigate the beam-domain channel estimation and power allocation in hybrid architecture massive multiple-input and multiple-output (MIMO) communication systems. First, we propose a low-complexity channel estimation method, which utilizes the beam steering vectors achieved from the direction-of-arrival (DOA) estimation and beam gains estimated by low-overhead pilots. Based on the estimated beam information, a purely analog precoding strategy is also designed. Then, the optimal power allocation among multiple beams is derived to maximize spectral efficiency. Finally, simulation results show that the proposed schemes can achieve high channel estimation accuracy and spectral efficiency.

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