Distributed Antenna Systems Research Articles

Power Allocation for Energy-Efficient Optimization in IoT-Based Distributed Antenna System With Imperfect Channel State Information

This article investigates energy efficiency (EE) maximization for an Internet of Things-based (IoT) distributed antenna system (DAS) with imperfect channel state information (CSI) subject to maximum transmit power and minimum data rate constraints. First, we derive achievable rates and corresponding EE expressions of the system for single and multiple IoT devices. Then, we formulate the EE maximization problem in the single-device IoT-DAS with imperfect CSI, and it has a special form of the difference of concave functions. To solve this problem, we develop a near-optimal power allocation (PA) scheme by using the concave–convex procedure (CCCP) and block coordinate descent (BCD) method. It can achieve an EE performance similar to that of the optimal exhaustive search scheme, but with lower complexity. Based on this result, we present a suboptimal PA scheme with a single-layer iteration to decrease the complexity and maintain a performance similar to that of the near-optimal scheme. Using the results above, the EE optimization for IoT-DAS with imperfect CSI for multiple devices is addressed. A near-optimal PA scheme based on the fractional programming (FP) theory as well as the CCCP and BCD methods for solving the optimization problem is presented. Also, a suboptimal PA scheme based on the FP theory and BCD method is developed to further decrease the complexity. Interestingly, these two schemes have the same performance for perfect CSI. Simulation results show the validity of the developed schemes and their superior performances over existing methods.

Improvement of Capacity and QoE: Distributed Massive MIMO (DM-MIMO) Technology-5G

Distributed massive MIMO is an arising answer for improve 5G limit, throughput, and QoE inside. There are various ways to advance indoor execution. The indoor cell network should have totally different qualities and needs from its outside partner, yet a consistent encounter should be kept up with while moving between the two. New arrangements, like small cells and distributed antenna systems (DAS), have been added to every portable age to work on the presentation and quality of experience (QoE) for indoor clients. Notwithstanding, the goal lines are moved with each new age of purpose cases, and, surprisingly, more significant levels of execution and QoE are required. The improvement in the indoor experience needed in the 5G period should be extensive. The 5G guidelines empower the organizations to help tremendous quantities of clients or associated gadgets in little spaces (up to 1 million for each square kilometer), while consuming information at multi-gigabit speeds and with low idleness and high unwavering quality. This paper give a brief review on improvement in channel capacity and QoE using massiveness of MIMO technology for 5G environment in distributed manner.

Energy Efficiency Optimization for D2D Underlay Communication in Distributed Antenna System over Composite Fading Channels

Energy Efficiency Optimization for D2D Underlay Communication in Distributed Antenna System over Composite Fading Channels

Energy-efficient simultaneous wireless information and power transfer-enabled orthogonal multiple access under distributed antenna systems

Energy-efficient simultaneous wireless information and power transfer-enabled orthogonal multiple access under distributed antenna systems

Coordinated distribution of stadium electric load unloading based on artificial intelligence

The Stadium’s Electricity (SE) is cost-effective and critical to meeting the stadium’s size requirements. Because of their complex internal operations and extensive functionality. Stadium energy efficiency improvements are demanding and time-consuming due to the large and diverse electricity loads that can be managed. The stadium source of information is unloaded and turned off after sports. During sports, the system is ready to be deployed in case of an electricity outage. Several of these issues must be carefully evaluated, starting with accurate representations and human-structure interaction models, and determining acceptable facility vibration serviceability limitations of crowd activities. Due to various factors, stadiums like those used for athletic or entertainment events are distinct from other civil engineering constructions. Stadiums are susceptible to both the coordinated and random motion of huge crowds, which presents several issues. In computer science, Artificial Intelligence (AI) refers to the development of machines that can simulate human mental processes. AI can be used in various ways, from natural language processing to speech recognition to computer vision. This paper introduced a new method for (SE-AI) in addition to enhancing stadium control capabilities in various functional areas. The intelligent stadium development effectively enables it to handle construction equipment in an integrated manner. In the stadium’s electrical design, the smart sports model is structured. An investigation of the stadium’s electrical design system to provide helpful information for the stadium’s electrical design work based on engineering design principles. Advanced technology is mirrored in the stadium’s equipment, which is moving toward informationization and intelligence due to the advancement of science and technology, especially digitalization. If the research results can be a helpful guide for bettering the electrical planning of stadiums can be a more substantial impact on society. Stadiums are investing in Wi-Fi and distributed antenna systems to boost connection. This allows viewers to follow the game throughout the stadium and helps scattered personnel communicate.

Another Perspective on Interference Channels for Non-Orthogonal Multiple Access Communications

In this letter, a new perspective on non-orthogonal multiple access (NOMA) is given, relying on the established model of interference channels (IC) from information theory. Establishing links with studies on ICs enables a new framework for the application of NOMA, especially in the context of distributed antenna systems. Thanks to this common framework, a fair and comprehensive evaluation of single antenna NOMA and IC-based NOMA is provided first. Then, a simple transmit coordination scheme, termed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">antenna switching</i> , is proposed to switch the IC scenario from strong to weak IC leading to an increase in the achievable capacity under some system and channel conditions. Finally an application example is provided to show the advantage of the proposed approach that enables to match the type of NOMA to the deployment context according to the desired trade off between system throughput and user fairness.

A Compact Triple-Band UWB Inverted Triangular Antenna with Dual-Notch Band Characteristics Using SSRR Metamaterial Structure for Use in Next-Generation Wireless Systems

A compact triple-band operation ultra-wideband (UWB) antenna with dual-notch band characteristics is presented in this paper. By inserting three metamaterial (MTM) square split-ring resonators (MTM-SSRRs) and a triangular slot on the radiating patch, the antenna develops measured dual-band rejection at 4.17–5.33 GHz and 6.5–8.9 GHz in the UWB frequency range (3–12 GHz). The proposed antenna offers three frequency bands of operation in the UWB range, which are between 3–4.17 GHz (~1.2 GHz bandwidth), 5.33–6.5 GHz (~1.17 GHz bandwidth), and 8.9–12 GHz (~3.1 GHz bandwidth), respectively. The higher resonating frequency band can be tuned/controlled by varying the width of the triangle slot, while the medium operational band can be controlled by adjusting the width of the SSRR slot. Initially, the simulated S-parameter response, 2D and 3D radiation patterns, gain, and surface current distribution of the proposed UWB inverted triangular antenna has been studied using epoxy glass FR4 substrate having parameters εr = 4.3, h = 1.6 mm, and tan δ = 0.025, respectively. In order to validate the simulation results, the proposed UWB antenna with dual-notch band characteristics is finally fabricated and measured. The fabricated antenna’s return-loss and far-field measurements show good agreement with the simulated results. The proposed antenna achieved the measured gain of 2.3 dBi, 4.9 dBi, and 5.2 dBi at 3.5 GHz, 6.1 GHz, and 9.25 GHz, respectively. Additionally, an in-depth comparative study is performed to analyze the performance of the proposed antenna with existing designs available in the literature. The results show that the proposed antenna is an excellent candidate for fifth-generation (5G) mobile base-stations, next-generation WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications.

Performance Evaluation of Reconfigurable Intelligent Surface against Distributed Antenna System at the Cell Edge

In small spaces in which typical cell towers cannot be constructed, distributed antenna systems (DASs) are the preferable approach for increasing network coverage, as they are a superior solution for congested, high-volume areas. However, due to their high cost and complexity in backhaul routing, reconfigurable intelligent surfaces (RISs) are a promising solution to overcome the major drawbacks of DAS systems while improving network coverage. Thus, this work investigated a correlation of execution in an RIS-aided system cell framework and DAS-aided system cell framework where a simple and precise structure for the performance measurement of area spectral efficiency (ASE) and energy efficiency (EE) under realistic channel presumptions was introduced. The analysis started with the downlink ergodic capacity with regards to the RIS framework and DAS framework under a generalized Nakagami-m fading channel with the presence of path-loss attenuation and interference from co-channel base stations (BSs), and was simplified further by utilizing a moment-generating function (MGF)-based approach. From the computed expression, the effects of traffic activity, EE and ASE were derived and analyzed for both systems in the presence of co-channel interference. The results were then verified by comparing them with Monte Carlo simulations, and the findings show that the two outcomes generally match. Based on these, it is demonstrated that the ASE performance of the RIS-assisted system in various traffic activity conditions outperforms the DAS-aided system; however, in high signal-to-noise (SNR) regions with full traffic activity, the ASEs are highest for both systems; by only 0.005 bits/s/Hz/km2.

A Sustainable Business Model for a Neutral Host Supporting 5G and beyond (5GB) Ultra-Dense Networks: Challenges, Directions, and Architecture.

With the deployment of the fifth generation (5G) mobile network systems and the envisioned heterogeneous ultra-dense networks (UDNs), both small cell (SmC) and distributed antenna system (DAS) technologies are required by mobile network operators (MNOs) and venue owners to support multiple spectrum bands, multiple radio access technologies (RATs), multiple optical central offices (COs), and multiple MNOs. As a result, the neutral host business model representing a third party responsible for managing the network enterprise on behalf of multiple MNOs has emerged as a potential solution, mainly influenced by the desire to provide a high user experience without significantly increasing the total cost of ownership (TCO). However, designing a sustainable business model for a neutral host is a nontrivial task, especially when considered in the context of 5G and beyond (5GB) UDNs. In this paper, under an integrated optical wireless network infrastructure, we review how SmC and DAS technologies are evolving towards the adoption of the neutral host business model and identify key challenges and requirements for 5GB support. Thus, we explore recent candidate advancements in heterogeneous network integration technologies for the realization of an efficient 5GB neutral host business model design capable of accommodating both SmC and DAS. Furthermore, we propose a novel design architecture that relies on virtual radio access network (vRAN) to enable real-time dynamic resource allocation and radio over Ethernet (RoE) for flexible and reconfigurable fronthaul. The results from our simulations using MATLAB over two real-life deployment scenarios validate the feasibility of utilizing switched RoE considering end-to-end delay requirements of 5GB under different switching schemes, as long as the queuing delay is kept to a minimum. Finally, the results show that incorporating RoE and vRAN technologies into the neutral host design results in substantial TCO reduction by about 81% in an indoor scenario and 73% in an outdoor scenario.

Passive Intermodulation Measurement: Challenges and Solutions

In modern wireless communication systems, the signal-to-noise ratio (SNR) is one of the most important performance indicators. When the other radio frequency (RF) performance of the components is well designed, passive intermodulation (PIM) interference may become an important factor limiting the system’s SNR. Whether it is a base station, an indoor distributed antenna system, or a satellite system, there are stringent PIM level requirements to minimize interference and enhance network capacity in multicarrier networks. Especially for systems of high power and wide bandwidth such as 5G wireless communication, PIM interference is even more serious. Due to the complexity and uncertainty of PIM, measurement is the most important means to study and evaluate the PIM performance of wireless communication systems. In this review, the current main PIM measurement methods recommended by International Electrotechnical Commission (IEC) and other standard organizations are introduced, and several key challenges in PIM measurement and their solutions (including the design of PIM tester, the location of the PIM sources, the design of compact PIM anechoic chambers, and the evaluation methods of PIM anechoic chambers) are highlighted. These challenges are of great significance to solve PIM problems that may arise during device characterization and verification in real wireless communication systems.

Secure energy efficiency: Power allocation and outage analysis for SWIPT-in-DAS based IoT

In this paper, we study secure energy efficiency (SEE) for simultaneous wireless information and power transfer (SWIPT) in a distributed antenna system (DAS) based IoT network. We consider a system in which both the legitimate user (Bob) and the eavesdropper (Eve) rely on the energy harvested from the received radio signal. Firstly, with perfect channel state information (CSI), we formulate the maximization of SEE as a constrained optimization problem. In this problem, we aim to highlight the advantage of SWIPT in exploiting the Eve’s energy harvesting requirement. This is achieved by defining a charge constraint in the SEE optimization problem which ensures that the Eve is deprived of its only energy source. Next, considering the fact that perfect CSI is hard to achieve in practice, we characterize the system performance in terms of the outage probability (OP) of SEE. For the given SWIPT-in-DAS setup, we derive the closed form expression for the OP of SEE and with the help of numerical results, we study the effect of transmit power levels, number of distributed antenna (DA) ports and the PS ratio of devices. To the best of our knowledge, this is the first attempt to define the OP of SEE for SWIPT-in-DAS.

Physical Layer Security in Distributed Antenna Systems Using One-Bit Feedback Information

This article concerns the physical layer security (PLS) problem in distributed antenna systems (DASs), where eavesdroppers are equipped with multiple antennas. If both legitimate transmitter (Alice) and receiver (Bob) broadcast wireless signals via a DAS, the channel state information (CSI) between Alice and Bob may be exposed to an eavesdropper (Eve) due to the broadcast nature of wireless signals. Based on the exposed CSI, Eve can use multiple antennas to improve the eavesdropping capability on the confidential message transmitted from Alice. The prior PLS approaches to defend against the eavesdropping attack have two limitations. The first limitation is to assume that the CSI of Bob is available to Alice. The second limitation is to assume that there is no error in the feedback CSIs. In this article, we propose a new PLS scheme of a DAS by using one-bit feedback information. The basic idea of our approach is to generate a null transmission vector from the distributed transmitters of Alice to Bob while using different artificial noise components to protect the exposure problem of CSI between Alice and Bob. The proposed scheme has the following advantages: improved secrecy rate, rapid convergence, and good performance under a time-varying channel. We implemented our scheme and conducted extensive performance comparisons through simulations. Our experimental results show that the proposed scheme improves the secrecy rate with 1.20 b/s/Hz as compared to prior approaches. At last, we present some interesting future works for the PLS problem in a DAS.

Dynamic ways of using DAS with reduced call drops and hands-off

In today’s digital era people are controlled by digital gadgets, Cellular Systems are the backbone of these gadgets or cellular systems. Current technologies are offering more facilities to their users and also have a few challenges. In a cellular system, call dropping is one of the challenging problems, which is faced by a mobile user in a network due to many reasons like availability of free channels, low level of system configuration, high traffic rate, etc. In this research study, among various failures handover failure is one of the major reasons for call drops. A dropped call happens when your phone gets disconnected somehow from the cellular network. Usually, this happens because of poor cell signal wherever you are that causes the call to drop. When a handover failure exists, a call drop occurs. Many different techniques are proposed and introduced to remove the call drop problem. In this research proposed a proper load balancing for cellular signals using networking for efficient call drop-down solutions with the concept of the distributed antenna system.

Performance of Remote Radio Unit Selection in Millimeter-Wave Distributed Antenna Systems Over Fluctuating Two-Ray Fading

Millimeter wave (mmWave) is a promising future wireless communication technology. To overcome the high path loss in mmWave band, distributed antenna systems (DASs) with each base station (BS) connecting to multiple remote radio units (RRUs) is a candidate solution. To better characterize the small-scale fading of mmWave channels, the fluctuating two-ray (FTR) was recently proposed. In this letter, we study the performance of RRU selection in mmWave DASs over the FTR fading. First, simplified closed-form expressions are, respectively, provided for the probability density function (PDF) and cumulative distribution function (CDF) of signal-to-noise ratio (SNR). Then, we derive the exact closed-form expressions and their high-SNR approximations for the outage probability and ergodic rate, respectively. The effect of RRU number and FTR-fading parameters on the performance are further revealed from these high-SNR approximations. Simulations validate our analytical results.

Metamaterial-Inspired Electrically Compact Triangular Antennas Loaded with CSRR and 3 × 3 Cross-Slots for 5G Indoor Distributed Antenna Systems.

In this article, two distinct kinds of metamaterial (MTM) antennas are proposed for fifth-generation (5G) indoor distributed antenna systems (IDAS). Both antennas operate in the sub-6 GHz 5G band, i.e., 3.5 GHz. The antenna’s radiating structure is based on a combination of triangular and rectangular patches, as well as two complementary split-ring resonators (CSRR) unit-cells etched on the top layer. The bottom layer of the first MTM antenna is a complete ground plane, while the bottom layer of the second MTM antenna is etched by a 3 × 3 cross-slot MTM structure on the ground plane. The use of these structures on the ground plane improves the antenna bandwidth. The proposed antennas are designed using two different substrates i.e., a high-end Rogers thermoset microwave materials (TMM4) substrate (h = 1.524 mm/εr = 4.5/tan δ = 0.002) and a low-end flame-resistant (FR4) epoxy glass substrate (h = 1.6 mm/εr = 4.3/tan δ = 0.025), respectively. The antenna designs are simulated using CST microwave studio, and in the end, the antenna fabrication is performed using FR4 substrate, and the results are compared. Furthermore, parametric analysis and comparative studies are carried out to investigate the performance of the designed antennas. The simulated and measured results are presented for various parameters such as return-loss, gain, and radiation pattern. The two MTM antennas have an overall dimension of 18 × 34 mm2, demonstrating that the proposed design is 60 percent smaller than a standard microstrip patch antenna (MPA). The two proposed MTM antenna designs with complete ground plane and 3 × 3 cross-slot MTM on the bottom layer using FR4 substrate have a measured gain/bandwidth characteristic of 100 MHz/2.6 dBi and 700 MHz/2.3 dBi, respectively.

Multi-Band Heterogeneous Wireless Network Architecture for Industrial Automation: A Techno-Economic Analysis

To attain automation across different applications, industries are beginning to leverage advancements in wireless communication technologies. A ”one-size-fits-all” solution cannot be applied since wireless technologies are selected according to application needs, quality of service requirements, and economic restrictions. To balance the trade-off between technical and economic requirements, a multi-band heterogeneous wireless network architecture is presented and discussed in this paper. Wireless local area network (WLAN) and distributed antenna system (DAS) with Long Term Evolution (LTE) are considered as the backbone for the multi-band heterogeneous network into which other wireless technologies can be integrated. The technical and economic feasibility of the network are evaluated through a techno-economic analysis (TEA). The economic feasibility of the proposed network is measured in terms of net present value while the technical feasibility is measured in terms of network throughput and latency. Finally, network performance for DAS with LTE and WLAN are verified using an NS3 simulator for machine-to-machine, real-time video, and high-definition video data transmissions. The TEA analysis showed that the number of DAS units required to achieve technical feasibility is less than WLAN units, but the overall cost of DAS units are higher compared to WLAN units, even without taking into consideration industrial, scientific, and medical band technologies.

QoE‐aware mobile computation offloading in mobile edge computing

AbstractDue to the rapid development of smart phone utilization, the use of fast response with delay sensitive applications leads to high traffic demands. These issues are not yet fulfill by current researchers. When there is a massive crowd of users gathering in hotspot areas such as, railway stations, corporate centers, and malls requires service accessing social networks, then there cause uncertain traffic with congestion and network delay. In this article, an Efficient Offloading Mechanism (EOM) is proposed to transfer the user's intensive computations to picocells, where each picocell (PE) is integrated with the functionalities of edge. Moreover, a novel distributed multihop mesh middle layer (DMMM) framework is proposed for seamless communication, where the self‐healing network provides high resilience, immediate response, and multiuser content sharing and saves battery power. Generally, a picocell is a distributed antenna system that is an alternative to the repeater utilized to extend wireless services to 100 users. An Adaptive Ant Optimization (AAO) algorithm is developed for backhaul routing conflicts. Simulation outcomes of EdgeCloudSim prove that the offloading tiny devices incorporated with considerable additional computational capacities to fulfill all the demands within 15 ms delay from each network.

RoF-based indoor distributed antenna system that can simultaneously support 5G mmWave and 6G terahertz services.

The telecommunication society is paving the way toward ultra-high frequency regions, including the millimeter wave (mmWave) and sub-terahertz (sub-THz) bands. Such high-frequency electromagnetic waves induce a variety of physical constraints when they are used in wireless communications. Inevitably, the fiber-optic network is deeply embedded in the mobile network to resolve such challenges. In particular, the radio-over-fiber (RoF)-based distributed antenna system (DAS) can enhance the accessibility of next-generation mobile networks. The inherent benefits of RoF technology enhance the DAS network in terms of practicality and transmission performance by enabling it to support the 5G mmWave and 6G THz services simultaneously in a single optical transport link. Furthermore, the RoF allows the indoor network to be built based on the cascade architecture; thus, a service zone can be easily added on request. This study presents an RoF-based multi-service DAS network and experimentally investigates the feasibility of the proposed system.

Optimal and Energy Effective Power Allocation Using Multi-Scale Resource GOA-DC-EM in DAS

Recently many algorithms for allocation of power approaches have been suggested to increase the Energy Efficiency (EE) and Spectral Efficiency (EE) in the Distributed Antenna System (DAS). In addition, the method of conservation developed for the allocation of power is challenging for the enhancement because of their high complication during estimation. With the intention of increasing the EE and SE, the optimization of allocation of power is done on the basis of capacity of the antenna. The main goal is for the optimization of the power allocation to improve the spectral and energy efficiency with the increased capacity of the cable with the help of an efficient optimal method with the model of clustering. In order to attain optimized allocation of power and for antenna optimization, the algorithm of Multi-scale Resource Grasshopper Optimization (MSR-GOA) is implemented. Besides, the clustering process is carried out using the algorithm for clustering namely Discriminative cluster-based Expectation Maximization (DC-EM) so as to minimize the rate of interference and computing complication. The analysis of performance is employed for evaluating the projected performance in various scenarios. The existing approach of investigation and comparison is made with the suggested system (DAS with MSR-GOA-DC-EM) with respect to EE and SE. From the analysis, it was apparent that the method projected here is highly efficient to provide high spectral and energy efficiency than the already available techniques.

Uplink Spectral Efficiency of Large, Distributed Antenna Systems With MMSE Processing

The spectral efficiency of a representative uplink in a wireless network with spatially distributed antennas and linear minimum-mean-square-error processing is found to approach an asymptote with a simple form as the number of antennas increases. These results generalize prior work which was applicable to systems with small numbers of base stations with large numbers of antennas each, to systems with large numbers of spatially distributed access points with small numbers of antennas each, and systems between these extremes. Additionally, these results are applied to systems where mobiles have multiple transmit antennas, and are used to characterize systems with both disjoint and user-centric clustering of cooperating base stations. Among other conclusions, these results indicate that with the same density and number of antennas cooperating to serve a mobile user, the uplink spectral efficiency with all antennas randomly distributed is several-fold higher than the case when the antennas are concentrated at one base station. These findings help improve our understanding of the tradeoffs involved in distributed antenna systems which have the potential to significantly increase data rates, but at a higher cost.