scholarly journals Efficient Resource Management for Sum Capacity Maximization in 5G NOMA Systems

2019 ◽  
Vol 2 (3) ◽  
pp. 27 ◽  
Author(s):  
Azhar Ali ◽  
Amna Baig ◽  
Ghulam Mujtaba Awan ◽  
Wali Ullah Khan ◽  
Zain Ali ◽  
...  
Keyword(s):  
Resource Management ◽  
Channel Assignment ◽  
Base Station ◽  
Management Problem ◽  
Optimization Scheme ◽  
Sum Capacity ◽  
Downlink Transmission ◽  
High Data ◽  
Capacity Maximization ◽  
Minimum Capacity

The modern cellular technologies are expected to provide high data rates and massive connectivity in fifth generation (5G) systems; however, this may be impossible through traditional radio access techniques. Recently, non-orthogonal multiple access (NOMA) has emerged as one of the promising cellular techniques for modern cellular communications with its ability to provide access for multiple users to the network over the same system resources. This paper studies resource management problem for downlink transmission of multiuser NOMA system. Our objective is to optimize both frequency and power resources for sum capacity maximization while taking into account each user minimum capacity requirement. Firstly, the problem of resource management decouples into two subproblems, that is, efficient sub-channel assignment and optimal power allocation, respectively. Secondly, for given power at base station, we design two sub-optimal algorithms for sub-channel assignment based on user channel condition and user minimum capacity requirement, respectively. Lastly, for any given sub-channel assignment, the problem first transforms into standard convex optimization problem and then we employ duality theory. To evaluate our proposed NOMA scheme, the enhanced version of existing NOMA optimization scheme is also presented as a benchmark. Results demonstrate that the proposed NOMA resource management scheme outperforms the benchmark NOMA optimization scheme in terms of sum capacity.

Lightbeam Configuration Method and Interference Elimination Resource Scheduling for Indoor Multibeam VLC Networks

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Cong-Nam Tran ◽  
Nam-Hoang Nguyen ◽  
Trong-Minh Hoang
Keyword(s):  
Transmission Rate ◽  
Resource Scheduling ◽  
Packet Delay ◽  
Access Point ◽  
Visible Light Communications ◽  
Resource Allocation Algorithm ◽  
Downlink Transmission ◽  
High Data ◽  
Interference Elimination ◽  
Multi Access

AbstractVisible light communications (VLC) is considered as an alternative communications technology for providing indoor wireless services. VLC systems are expected to offer high data transmission rate and seamless coverage. In order to achieve these requirements, VLC systems utilizing multi-lightbeam access points (multibeam VLC-AP) for downlink transmission have been proposed recently. In this paper, we present a lightbeam configuration method and an interference elimination resource scheduling mechanism (IERS) for indoor multibeam multi-access point VLC systems. The proposed lightbeam configuration method ensures seamless connectivity between user equipment and VLC-AP. The proposed IERS mechanism consists of a beam assignment algorithm and a resource allocation algorithm for eliminating co-channel interference as well as improving system performance. Performance results obtained by computer simulation indicate that there are significant improvements in terms of downlink signal to interference plus noise ratio, user throughput and packet delay when the proposed IERS mechanism is deployed.

scholarly journals Improved Water-Filling Power Allocation for Energy-Efficient Massive MIMO Downlink Transmissions

2017 ◽  
Vol 63 (1) ◽  
pp. 79-84
Author(s):  
M. K Noor Shahida ◽  
Rosdiadee Nordin ◽  
Mahamod Ismail
Keyword(s):  
Power Allocation ◽  
Network Architecture ◽  
Massive Mimo ◽  
Multiple Input Multiple Output ◽  
Base Station ◽  
Downlink Transmission ◽  
Allocation Algorithm ◽  
Mimo Antenna ◽  
Water Filling ◽  
Water Filling Algorithm

Abstract Energy Efficiency (EE) is becoming increasingly important for wireless communications and has caught more attention due to steadily rising energy costs and environmental concerns. Recently, a new network architecture known as Massive Multiple-Input Multiple-Output (MIMO) has been proposed with the remarkable potential to achieve huge gains in EE with simple linear processing. In this paper, a power allocation algorithm is proposed for EE to achieve the optimal EE in Massive MIMO. Based on the simplified expression, we develop a new algorithm to compute the optimal power allocation algorithm and it has been compared with the existing scheme from the previous literature. An improved water filling algorithm is proposed and embedded in the power allocation algorithm to maximize EE and Spectral Efficiency (SE). The numerical analysis of the simulation results indicates an improvement of 40% in EE and 50% in SE at the downlink transmission, compared to the other existing schemes. Furthermore, the results revealed that SE does not influence the EE enhancement after using the proposed algorithm as the number of Massive MIMO antenna at the Base Station (BS) increases.

scholarly journals Joint 3-D Positioning and Power Allocation for UAV Relay Aided by Geographic Information

2021 ◽  
Author(s):  
Pengfei Yi ◽  
Liang Zhu ◽  
Lipeng Zhu ◽  
Zhenyu Xiao
Keyword(s):  
Power Allocation ◽  
Upper Bound ◽  
Three Dimensional ◽  
Geographic Information ◽  
Base Station ◽  
Lagrangian Multipliers ◽  
Loop Optimization ◽  
Convex Problem ◽  
Communication Links ◽  
Minimum Capacity

<div>In this paper, we study to employ geographic information to address the blockage problem of air-to-ground links between UAV and terrestrial nodes. In particular, a UAV relay is deployed to establish communication links from a ground base station to multiple ground users. To improve communication capacity, we fifirst model the blockage effect caused by buildings according to the three-dimensional (3-D) geographic information. Then, an optimization problem is formulated to maximize the minimum capacity among users by jointly optimizing the 3-D position and power allocation of the UAV relay, under the constraints of link capacity, maximum transmit power, and blockage. To solve this complex non-convex problem, a two-loop optimization framework is developed based on Lagrangian relaxation. The outer-loop aims to obtain proper Lagrangian multipliers to ensure the solution of the Lagrangian problem converge to the tightest upper bound on the original problem. The inner-loop solves the Lagrangian problem by applying the block coordinate descent (BCD) and successive convex approximation (SCA) techniques, where UAV 3-D positioning and power allocation are alternately optimized in each iteration. Simulation results confifirm that the proposed solution signifificantly outperforms two benchmark schemes and achieves a performance close to the upper bound on the UAV relay system.</div>

Performance Analysis of Low Complexity Multiuser Scheduling Algorithms in MIMO System

2013 ◽  
Vol 392 ◽  
pp. 867-871
Author(s):  
Ming Xia Lv ◽  
Yan Kun Lai ◽  
Dong Tang
Keyword(s):  
Mimo System ◽  
Scheduling Algorithm ◽  
Low Complexity ◽  
Base Station ◽  
User Scheduling ◽  
Sum Capacity ◽  
Multiuser Scheduling ◽  
The Common ◽  
The Cost ◽  
Selection Algorithms

The total throughput of the communication system can be maximized by allocating the common radio resource to the user or the user group having the best channel quality at a given time and the multiuser diversity gain can be obtained when multiple users share the same channel at one time. The object to select the users is to select the users with the maximum sum capacity. As for a scheduling algorithm, exhaustive algorithm can get the largest capability of the system by multi-user scheduling. However, this algorithm is quite complex hence the cost of operation to a base station has substantial increased. We compare the multiuser performance of two fast user selection algorithms with low complexity in MIMO-MRC systems with co-channel interferences. From the simulation results, these two algorithms not only decrease the computational complexity of the scheduling algorithm but also retain large capability of the MIMO system.

Using a Sorted QR Decomposition Algorithm for Multiuser MIMO Downlink Transmission

2021 ◽  
Vol I (I) ◽  
Author(s):  
S Lakshmi Narayanan ◽  
Robert Theivadas J
Keyword(s):  
Bit Error Rate ◽  
Spectral Efficiency ◽  
Large Scale ◽  
Qr Decomposition ◽  
Decomposition Algorithm ◽  
Wireless Technology ◽  
Multiuser Mimo ◽  
Downlink Transmission ◽  
High Data ◽  
Mimo Downlink

MIMO is a wireless technology that uses large scale antennas to transfer more data at the same time and to increase spectral efficiency. To achieve high data rate with less bandwidth we use decomposition algorithm. Among various de-composition algorithm QR decomposition algorithm outperforms low bit error rate(BER), but the computational complexity is prohibitively high when the system incorporates large number of antennas. This paper presents a low computational sorted QR decomposition (SQRD) algorithm for MIMO.SQRD uses precoding technique at the transmitter which decomposes the channel that can sent in parallel.

Handoff Management in Macro-Femto Cellular Networks

2019 ◽  
pp. 227-249
Author(s):  
Muhammad Faheem Mustafa ◽  
Ayaz Ahmad ◽  
Raheel Ahmed
Keyword(s):  
Cellular Networks ◽  
Base Station ◽  
Data Traffic ◽  
Core Network ◽  
Handoff Management ◽  
High Data ◽  
Cell Network ◽  
Network Operation ◽  
Comprehensive Survey ◽  
Time Required

With the rapid increase in data traffic and high data rate demands from cellular users, conventional cellular networks are becoming insufficient to fulfill these requirements. Femto cells are integrated in macro cellular network to increase the capacity, coverage, and to fulfill the increasing demands of the users. Time required for handoff process between the cells became more sensitive and complex with the introduction of femto cells in the network. Public internet which connect the femto base station with the mobile core network induces higher latency if conventional handoff procedures are also employed in macro-femto cell network. So, handoff process will become slower and network operation will become insufficient. Some standards, procedures, and protocols should be defined for macro-femto cell network rather than using existing protocols. This chapter presents a comprehensive survey of handoff process, types of handoff in macro-femto cell network, and proposed methods and schemes for frequent and unnecessary handoff reduction for efficient network operation.

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