Macro Cell Research Articles

Movement Aware CoMP Handover in Heterogeneous Ultra-Dense Networks

The densification of base station (BS) deployments is driving the evolution of network structures towards heterogeneous ultra-dense networks (UDN), making coordinated multipoint (CoMP) a viable and promising transmission solution. However, the BS cooperation regions formed by applying CoMP in the UDN are small and irregular, which causes frequent handover for mobile users. Different from most existing work that focus on the trigger time of handover, we explore how to choose the appropriate BS cooperation set to reduce handover rate. In this paper, we consider movement aware CoMP handover (MACH). By estimating cell dwell time, a user would be intelligently assigned to macro cell or small cell according to its movement trend. To enhance reliability, we further proposed improved MACH (iMACH) to achieve a trade-off between BSs with long dwell time and the current best performed BS for multipoint cooperation while user moving. Using stochastic geometry method, expressions of coverage probability, handover probability and throughput that characterize performance of the proposed schemes are derived. The numerical results indicate that the theoretical analyses fit the simulation results well and the proposed schemes surpass the existing schemes in terms of the aforementioned metrics, and more intelligent and suitable for ultra-dense scenarios.

Energy Efficiency and Hover Time Optimization in UAV-Based HetNets

In this article, we investigate the downlink performance of a three-tier heterogeneous network (HetNet). The objective is to enhance the edge capacity of a macro cell by deploying unmanned aerial vehicles (UAVs) as flying base stations and small cells (SCs) for improving the capacity of indoor users in scenarios such as temporary hotspot regions or during disaster situations where the terrestrial network is either insufficient or out of service. UAVs are energy-constrained devices with a limited flight time, therefore, we formulate a two layer optimization scheme, where we first optimize the power consumption of each tier for enhancing the system energy efficiency (EE) under a minimum quality-of-service (QoS) requirement, which is followed by optimizing the average hover time of UAVs. We obtain the solution to these nonlinear constrained optimization problems by first utilizing the Lagrange multipliers method and then implementing a sub-gradient approach for obtaining convergence. The results show that through optimal power allocation, the system EE improves significantly in comparison to when maximum power is allocated to users (ground cellular users or connected vehicles). The hover time optimization results in increased flight time of UAVs thus providing service for longer durations.

Performance evaluation of beamforming for network throughput enhancement

SummaryWith the advancement of mobile networks, the demand for increased throughput is continuously rising. Throughput is the amount of error‐free bits transmitted in a given period of time. Heterogeneous networks (HetNet) are widely accepted to enhance the throughput as they do have low pathloss among the others. HetNet deploys another cell under the coverage area of the macro cell. The HetNet offloads the macro cell that avoids congestion and enhances the coverage of the network. In HetNet, however, intercell interference is a major challenge that adversely degrades the throughput. In this paper, coordinated multipoint transmission (CoMP) along with a coordinated beamforming (CBF) is integrated to mitigate the intercell interference (ICI). In general, the results have shown that the proposed technique has resulted into significant interference reduction and hence improved throughput and spectral efficiency.

Low-Resolution ADC Quantized Full-Duplex Massive MIMO-Enabled Wireless Backhaul in Heterogeneous Networks Over Rician Channels

This paper studies the spectral/energy efficiency (SE/EE) of a heterogeneous network with the backhaul enabled by low-resolution analog-to-digital converters (ADCs) quantized full-duplex massive multiple-input multiple-output (MIMO) over Rician channels. Backhaul communication is completed over two phases. During the first phase, the macro-cell (MC) base station (BS) deploys massive receive antennas and a few transmit antennas; the small-cell (SC) BSs employ large-scale receive antennas and a single transmit antenna. For the second phase, the roles of the transmit and receive antennas are switched. Due to the low-resolution ADCs, we account for quantization noise (QN). We characterize the joint impact of the number of antennas, self-interference, SC-to-SC interference, QN, and Rician $K$ -factor. For the first phase, the SE is enhanced with the massive receive antennas and the loss due to QN is limited. For the second phase, the desired signal and QN have the same order. Therefore, the SE saturates with the massive transmit antennas. As the Rician $K$ -factor increases, the SE converges. Power scaling laws are derived to demonstrate that the transmit power can be scaled down proportionally to the massive antennas. We investigate the EE/SE trade-offs. The envelope of the EE/SE region grows with increase in the Rician $K$ -factor.

Dynamic and location‐based power allocation mechanism for inter‐cell interference mitigation in 5G heterogeneous cellular network

SummaryIn this paper, a dynamic and location‐based power allocation mechanism is proposed which could be adopted at both macrocell (MC) and overlaid fixed/mobile small cells (SCs) to mitigate inter‐cell interference (ICI) effects in heterogeneous cellular networks (HetCNs). The proposed Dynamic Power Allocation based on User Location (DPAUL) mechanism allows both MCs and deployed fixed/mobile SCs to dynamically allocate transmit power to its serving base stations (BSs) based on the location of a user in the cell. The paper illustrates the mitigation of dynamic downlink interferences occurring due to the mobility of SCs and users. The mobility of cell and its users is analyzed by introducing the Cell‐User mobility (CUM) model in the network. The proposed DPAUL mechanism is compared with the authors' other ICI mitigation techniques: Dynamic Fixed Region Cooperation (DFRC) and Dynamic Power Allocation Mechanism (DPAM). The network metrics Sumrate, User throughput, Energy‐efficiency, and Outage probability are investigated with allocation of sub 6 GHz and mmWave spectrums at MCs and fSCs/mSCs, respectively.

Apixaban Downregulates Endothelial Inflammatory and Prothrombotic Phenotype in an In Vitro Model of Endothelial Dysfunction in Uremia.

Chronic kidney disease (CKD) associates with inflammatory and prothrombotic phenotypes, resulting in higher cardiovascular risk. Factor Xa displays functions beyond coagulation, exhibiting proinflammatory effects. The aim of the present study was to investigate whether a direct FXa inhibitor protects from the endothelial dysfunction (ED) caused by uremia. Macro (HUVEC) and microvascular (HMEC) endothelial cells (ECs) were exposed to serum from uremic patients or healthy donors, in absence and presence of apixaban (60 ng/ml). We evaluated changes in surface VCAM-1 and ICAM-1, intracellular eNOS, reactive oxygen species (ROS), and von Willebrand Factor (VWF) production by immunofluorescence, reactivity of the extracellular matrix (ECM) towards platelets, and intracellular signaling. ECs exposed to uremic serum triggered dysregulation of all the parameters. Presence of apixaban resulted in decreased expression of VCAM-1 (178 ± 14 to 89 ± 2% on HMEC and 324 ± 71 to 142 ± 25% on HUVEC) and ICAM-1 (388 ± 60 to 111 ± 10% on HMEC and 148 ± 9% to 90 ± 7% on HUVEC); increased eNOS (72 ± 8% to 95 ± 10% on HMEC); normalization of ROS levels (173 ± 21 to 114 ± 13% on HMEC and 165 ± 14 to 127 ± 7% on HUVEC); lower production of VWF (168 ± 14 to 92 ± 4% on HMEC and 151 ± 22 to 99 ± 11% on HUVEC); and decreased platelet adhesion onto ECM (134 ± 22 to 93 ± 23% on HMEC and 161 ± 14 to 117 ± 7% on HUVEC). Apixaban inhibited p38MAPK and p42/44 activation in HUVEC (139 ± 15 to 48 ± 15% and 411 ± 66 to 177 ± 57%, respectively) (p < 0.05 vs control for all parameters). Anti-FXa strategies, such as apixaban, prevented ED caused by the uremic milieu, exhibiting anti-inflammatory and antioxidant properties and modulating the reactivity of the ECM.

RETRACTED ARTICLE: Adaption of 5G networks in industrial sector with improved bandwidth utilization

The newly arrived Software Defined Network (SDN) has been adapted to industry standards. By defining Software Defined Air Interface (SDA) would support achieving higher data rate and utilization of bandwidth. The growing use of internet in industrial sector has claimed higher bandwidth conditions. To provide sufficient bandwidth support for the industrial networks, the fifth generation network has been emerged. The industrial sector utilizes the internet communication for variety of purpose where the bandwidth of the connections needs higher values. They involve in accessing different resources located in different geographic location where the latency of communication should be less and they need to transfer huge amount of data which requires higher bandwidth conditions. However, the increased growth of internet usage has introduced huge challenge for the service providers in handling higher data rate solutions. However different opinions are generated toward 5G network design, still there is no blue print has been arrived. Towards the growth of 5G networks and for the improved performance of data rate maintenance, a novel software defined air interface has been proposed in this paper. The presence of macro cells and small cells supports the higher data rate. Each small cell has been fabricated with number of MIMO which is located in different locations of the network in dense. The software defined interface is capable of selecting optimal macro station or small cell for betterment of data transmission. The interface designed monitor the network conditions and estimates bandwidth utilization support (BUS) and data rate maintenance support (DMS) for different small cells located in different geographic location. The SDA designed is responsible for the selection of small cell, MIMO to maintain the data rate. The proposed method improves the performance of bandwidth utilization and data rate maintenance.

The importance of spatio-temporal infrastructure assessment: Evidence for 5G from the Oxford–Cambridge Arc

The roll-out of 5G infrastructure can provide enhanced high capacity, low latency communications enabling a range of new use cases. However, to deliver the improvements 5G promises, we need to understand how to enhance capacity and coverage, at reasonable cost, across space and over time. In this paper, we take a spatio-temporal simulation modeling approach, using industry-standard engineering models of 5G wireless networks, to test how different infrastructure strategies perform under scenarios of uncertain future demand. We use coupled open-source models to analyze a UK growth corridor, a system-of-cities comprising 7 urban areas, known as the Oxford-Cambridge Arc. We find that population growth has a marginal impact on total demand for 5G (up to 15%), as the main factor driving demand is the increase in per user data consumption resulting mainly from video. Additionally, the results suggest only limited justification for deploying 5G based purely on the need for more capacity. Strategies which reuse existing brownfield Macro Cell sites are enough to meet future demand for Enhanced Mobile Broadband, except in the densest urban areas. While spatio-temporal analysis of infrastructure is common in some sectors (e.g. transport, energy and water), there has been a lack of open analysis of digital infrastructure. This study makes a novel contribution by providing an open and reproducible spatio-temporal assessment of different 5G technologies at a time when 5G is starting to roll-out around the world.

Nearest Distance Based Downlink Rate Modeling in Hyper-dense Heterogeneous Wireless Cell Networks

Different kinds of low transmit power, flexible cell extension and hyper dense base stations (BSs) overlaying on the well established macro cells, forming the hyper-dense multilayer heterogeneous wireless cell networks (HetNets), where the BSs in each tier are characterized by the differences in BSs transmit power, path loss exponent, tier-biasing factor and BSs spatial density, is the promising technology for 5th generation mobile networks and to support hot spots and cell edge coverage. The HetNets downlink rate modeling is one of the key and challenge problems for the random deployment characteristics of BSs in lower layer. In this paper, a three tier HetNets, which includes macro tier, Pico tier and Femto tier, is first modeled with the spatial point process in stochastic geometry theory; then, considering the BSs low transmit power, flexible cell extension and hyper BSs spatial density, a tractable downlink rate model based on the nearest distance and bias accepted factor is proposed, which adopt stochastic geometry theory and is easy to compute; last, the proposed downlink rate model is validated by numerical examples to confirm that the flexible cell extension BSs deployment in complex high traffic area with different path loss exponent is an effective scheme to improve quality of service.

Dynamic and energy‐efficient ICI mitigation techniques for mobility‐based 5G HetCN

In this study, two dynamic mechanisms are proposed to mitigate inter-cell interference (ICI) in the heterogeneous cellular network (HetCN) namely: Dynamic Fixed Region Cooperation (DFRC) and Dynamic Power Allocation Mechanism (DPAM). The DFRC allows serving mSCs and other interfering base stations (BSs) to cooperate during transmission of a signal to a user. The DPAM dynamically allocates power to serving BS based on the farthest user in a cell. The study illustrates downlink interferences typically linked with a HetCN. For analysis, a macrocell (MC) network distributed with heterogeneous users is overlaid with both fixed and mobile small cells (SCs). The authors also introduced the cell-user mobility model for deployed mobile SCs in the network. The effects on network performance metrics: Sumrate, Average user throughput, and Energy efficiency are investigated with an allocation of sub 6 GHz and mmWave bands at MC and deployed SCs, respectively.

Semi-Distributed Joint Power and Spectrum Allocation for LAA Based Small Cell Networks

In licensed assisted access (LAA) based small cell networks (SCNs), the small base station (SBS) can reuse the uplink licensed bands with the macro cell while sharing the unlicensed bands with the Wi-Fi networks to improve its throughput. To mitigate the severe co-channel interference to the macro cell and guarantee the harmonious coexistence with the Wi-Fi networks, the spectrum and power should be jointly allocated at the SBSs. Moreover, to overcome the overwhelming signaling overheads introduced by the traditional centralized scheme and adapt to the variable radio environments, an adaptive decentralized scheme is necessary. Therefore, in this paper, an adaptive semi-distributed scheme is proposed to jointly allocate the power and spectrum on both licensed and unlicensed bands, which can achieve the global optimal spectrum efficiency (SE) of the SCNs. The proposed scheme can enable the SBSs to work independently and adaptively without sharing the whole information of the SBSs, but requires some Lagrangian parameters exchange via the coordination of the macro base station (MBS). Theoretical analysis and numerical results are presented to show that the proposed scheme is capable of achieving the optimal SE on both licensed and unlicensed bands adaptively while confining the co-channel interference to the MBS and guaranteeing the fair coexistence with the Wi-Fi network.

Maximising system throughput in wireless powered sub-6 GHz and millimetre-wave 5G heterogeneous networks

Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (µWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughput.

Connecting the Unconnected: Toward Frugal 5G Network Architecture and Standardization

This article adopts a holistic approach to address the problem of poor broadband connectivity in rural areas by suggesting a novel wireless network architecture, also called the "Frugal 5G Network". To arrive at the Frugal 5G Network architecture, we take into consideration the rural connectivity needs and the characteristics specific to rural areas. As part of the proposed Frugal 5G Network, we define a heterogeneous Access Network wherein macro cells provide a carpet coverage while Wireless Local Area Networks (WLANs) provide additional capacity to serve the village clusters. WLAN is backhauled via a wireless network also called the wireless middle mile network. We define a Software Defined Networking (SDN) and Network Function Virtualization (NFV) based architecture to make the network flexible and scalable. The concepts of Fog computing have also been employed in the network architecture to bring intelligence to the edge, i.e., to the access network. Through a novel amalgamation of these technologies, we are able to address the connectivity requirements of rural areas. The proposed network architecture can serve as a potential solution towards IEEE P2061, a standardization project that aims to design an architecture to facilitate rural broadband communication.

Smart Mode Selection Using Online Reinforcement Learning for VR Broadband Broadcasting in D2D Assisted 5G HetNets

As an emerging broadband service pattern in the 5G era, VR broadcasting needs a considerable amount of bandwidth and strict quality of service (QoS) control. The traditional eMBMS or enTV transmission mode in HetNets consisting of macro cells and small cells cannot bring about a good trade-off between broadband performance and resource utilization for VR broadcasting service. D2D multicasting applied to VR broadcasting can improve the performance of edge users and resource utilization. Motivated by the rapid development of AI techniques, this paper proposes a novel hybrid transmission mode selection based on online reinforcement learning to address this problem. Each VR broadband user can be associated by one of the three modes: macrocell broadcasting, mmWave small cell unicasting and D2D multicasting. This paper first models this intelligent mode decision process as a problem to pursue the optimal system throughput. Then, an online machine learning-based method is proposed to solve this problem, which consists of a fast D2D clustering module based on unsupervised learning and a smart mode selection module based on reinforcement learning. The simulation results verify that the WoLF-PHC and Nash Q-learning perform better than other algorithms in large-scale scenarios and small-scale scenarios, respectively. The proposed intelligent transmission mode selection can also achieve larger VR throughput than traditional broadcasting strategies with a good balance between broadband performance and resource utilization.

5G Cellular High Data Rate, Fading Resilient Transceiver Broadcast in LTE-Advanced 802.16m WiMAX-Based Wireless Networks

The fifth generation (5G) cellular wireless network are alleged to conquer the central difficulties of existing cellular network, higher data rates, excellent end to-end performance and user coverage in hot spot and swarmed territories with lower latency, energy utilization and value per information transfer. to handle these difficulties, 5G systems will embrace a multi-level design comprising of macro cells, distinctive types of authorized little cells, transfers, and gadget to-gadget (D2D) systems to serve users with various nature of-benefit (QoS) prerequisites in an exceedingly spectrum and energy effective way. Beginning with the dreams and prerequisites of 5G multi-level systems, this postulation traces the difficulties of interference administration (control, cell relationship) in these systems with shared spectrum get to (when the various system levels share the identical authorised spectrum. during this specific situation, a subjective correlation of the present cell association and power control plans is given to our work to interference management in 5G systems.

Energy-efficient 5G cloud RAN with virtual BBU server consolidation and base station sleeping

Heterogeneous network (HetNet) deployment where macro cells are overlaid by small cells is considered a de-facto solution for meeting the ever increasing mobile traffic demand in fifth generation (5G) networks. However, deployment of a large number of small cell base stations (BSs) result in considerable increase in HetNet energy consumption. Cloud radio access networks (C-RAN) has been proposed as an energy-efficient architecture that leverages cloud computing technology where baseband processing is performed in virtual baseband units (vBBU) in the BS cloud. In this paper, we address the energy efficiency (EE) optimization problem in the downlink for two-tier heterogeneous C-RAN (H-CRAN) comprising of macro and pico-cells. At the radio side of H-CRAN, a dynamic pico BS switching OFF algorithm based on a utility function is proposed while maintaining coverage and quality of service (QoS). In the cloud side, heuristic approximation algorithms are proposed including simulated annealing (H-CRAN SA) and genetic algorithm (H-CRAN GA) to minimize energy consumption by reducing the number of BBU servers used through vBBU placement. The proposed scheme is compared with distributed long term evolution advanced (LTE-A) Hetnet system and simulation results show that the proposed H-CRAN SA and H-CRAN GA schemes save 48% and 45% of energy on a daily average, respectively while maintaining the required QoS.

UAV-Assisted Networks Through a Tunable Dependent Model

In existing works of performance analysis of unmanned aerial vehicle (UAV) assisted networks, the location dependence between macro base stations (MBSs) and UAVs has not been considered. Considering UAV's particular agility, this letter proposes a tunable model for dependent deployment, and analyzes the performance of the setup via stochastic geometry. Specifically, to avoid the strong mutual interference between UAVs and MBSs, UAVs are only deployed in the macro cell boundaries, of which area fraction can be adjusted. In addition, we obtain a lower bound on the coverage probabilities (CPs) of MBS users and CP expression of UAV users. The results show that the CPs of UAV users in cell boundaries are significantly increased about 51% by the selective addition of UAVs, when signal to interference ratio (SIR) threshold equals 0dB, compared with the scenario of a single MBS tier network.

Analysis of the decoupled uplink downlink technique for varying path loss exponent in multi-tier HetNet

In this paper, the impact of varying path loss exponent (PLE) on user association probability, decoupled uplink coverage probability as well as decoupled uplink average spectral efficiency in downlink uplink decoupled (DUDe) multi-tier heterogeneous networks, is investigated. We investigate the effect of the difference in path loss exponents in both macro and small cell environments over uplink network performance. It is assumed that the mobile user connected to the macro base station experience different path loss exponent as compared to when connected to small base station. It is observed that the difference of path loss exponents in both cases has significant effect on the user association probability, decoupled uplink coverage probability as well as decoupled uplink average spectral efficiency. Moreover, in order to further support key findings and make sound comparison between coupled and DUDe performance in varying PLE environment, generalized analytical expressions for coupled association probabilities, along with coupled uplink coverage probability and coupled uplink average spectral efficiency have been derived. The analytical results evaluated in this paper are compared with the computer simulation and found in good agreement. Our analysis shows that decoupling technique performs suboptimal for cases where the environments around macro and small base stations are different with respect to each other. The work explained in this paper highlights the limitation of applying DUDe technique in realistic conditions where the PLEs of cellular tiers are not exactly equal to one another.

A Survey on Hybrid, 3D, Interference Mitigation and Secure Data Beamforming Techniques for 5G System

By 2020 world will testimony new archaic Multi-antenna technologies like beamforming along with massive multiple-input multiple-output in 5G system. The cellular networks with 5th Generation (5G) are introduced with the determined aim of supporting a very heterogeneous service mixture, everyone with its individual detailed requirements. It largely leverages a very huge count of independently controllable antennas at the BS, and thereby attains greater enhancement regarding the energy and spectral efficiency. This paper elucidate about the Hybrid Beamforming techniques, 3D beamforming techniques, Interference mitigation between small and macro cell beamforming proficiency and secure data transmission pre-owned in beamforming technologies dispense a comprehensive analysis of all aspect of Beamforming technologies used in 5G systems.

Clustering-Based Resource Allocation Scheme for Dense Femtocells (CRADF) to Improve the Performance of User Elements

Femtocells are densely deployed in the next generation heterogeneous cellular networks (HetNet) to improve the user performance and capacity of the cellular system. In LTE-A HetNet, multiple femto base stations (F-eNBs) sharing the spectrum with macro base station (M-eNB), create interference environment. This can be controlled by effective resource allocation scheme. In this paper, the clustering-based resource allocation scheme for dense femtocells (CRADF) is proposed to allocate suitable channels for user elements (UEs) at the dense femtocells. Most of the existing resource allocation schemes effectively assign the channels to femtocell users and mitigate the interference between the small cells and do not consider the interference from the macrocell elements. The proposed clustering-based resource allocation scheme effectively assigns the channels to UEs of both macro and femto cells in the dense LTE-A HetNet. The UE performance of the dense femtocell is analyzed for varying UE density conditions. The interference among the UEs from the macro and femtocell is quantified using graph-based technique and subsequently, the CRADF technique is used to assign the suitable channels to UE. The experimental results showed that our proposed work improved the average throughput of UE and restricted the subband handoff in the dense femtocells environment.