Local Multipoint Distribution Service Research Articles

Bandwidth enhancement of millimeter-wave microstrip patch antenna array for 5G mobile communication networks

This paper proposed enhancing the bandwidth of a millimeter wave microstrip patch antenna (MPA) and its array for a 5G mobile communication network. The proposed antenna is designed and fabricated on a Rogers RT Duroid 5,880 substrate with a standard thickness of 0.5 mm, a relative dielectric constant of 2.2, and a tangent loss of 0.0009. With a center frequency of 28 GHz, a measured return loss of -21.37 dB, a bandwidth of 1.14 GHz, and a gain of 6.27 dBi, the proposed single element operates in the local multipoint distribution service band. The proposed antenna is designed and manufactured as an array of 1×2 and 1×4 elements. The 2-element MPA array has a measured bandwidth of 1.207 GHz and a gain of 7.76 dBi, higher than that of a single element. The 4-element MPA array achieved a measured bandwidth of 2.685 GHz and a gain of 9.87 dBi, which is higher than the 2-element and single-element arrays at 28 GHz. This demonstrates that the array of antennas improves gain and bandwidth significantly. Hence, the proposed antenna and array are suitable for 5G mobile communication networks due to their small size.

Bandwidth enhancement of millimeter-wave microstrip patch antenna array for 5G mobile communication networks

This paper proposed enhancing the bandwidth of a millimeter wave microstrip patch antenna (MPA) and its array for a 5G mobile communication network. The proposed antenna is designed and fabricated on a Rogers RT Duroid 5,880 substrate with a standard thickness of 0.5 mm, a relative dielectric constant of 2.2, and a tangent loss of 0.0009. With a center frequency of 28 GHz, a measured return loss of -21.37 dB, a bandwidth of 1.14 GHz, and a gain of 6.27 dBi, the proposed single element operates in the local multipoint distribution service band. The proposed antenna is designed and manufactured as an array of 1×2 and 1×4 elements. The 2-element MPA array has a measured bandwidth of 1.207 GHz and a gain of 7.76 dBi, higher than that of a single element. The 4-element MPA array achieved a measured bandwidth of 2.685 GHz and a gain of 9.87 dBi, which is higher than the 2-element and single-element arrays at 28 GHz. This demonstrates that the array of antennas improves gain and bandwidth significantly. Hence, the proposed antenna and array are suitable for 5G mobile communication networks due to their small size.

Broadband Microstrip Antenna for 5G Wireless Systems Operating at 28 GHz

Communication systems have been driven towards the fifth generation (5G) due to the demands of compact, high speed, and large bandwidth systems. These types of radio communication systems require new and more efficient antenna designs. This article presents a new design solution of a broadband microstrip antenna intended for use in 5G systems. The proposed antenna has a central operating frequency of 28 GHz and can be used in the LMDS (local multipoint distribution service) frequency band. The dimensions of the antenna and its parameters have been calculated, simulated, and optimized using the FEKO software. The antenna has a compact structure with dimensions (6.2 × 8.4 × 1.57) mm. Rogers RT Duroid 5880 material was used as a substrate for the antenna construction, which has a dielectric coefficient of 2.2 and a thickness of 1.57 mm. The antenna described in the article is characterized by a low reflection coefficient of −22.51 dB, a high energy gain value of 3.6 dBi, a wide operating band of 5.57 GHz (19.89%), and high energy efficiency.

Fast and Accurate Modeling of Dual-Polarized Reflectarray Unit Cells Using Support Vector Machines

This paper describes the characterization of reflectarray unit cells using support vector machines (SVMs) to obtain fast and accurately the full matrix of reflection coefficients, which is used for an analysis of dual-polarized reflectarrays, demonstrating the performance of the model. First, a surrogate model of the reflectarray unit cell is obtained using SVMs. To this end, a set of random samples of the reflection coefficient matrix with a full-wave method of moments based on local periodicity (MoM-LP) is used to train the SVMs. To efficiently obtain the surrogate model, a novel strategy to accelerate the training process is presented, remarkably reducing computing time. Next, the model is tested against a different set of samples, obtaining an excellent agreement between the SVM model and MoM-LP simulations for all reflection coefficients, including the cross-coefficients. The surrogate model is then used for an efficient analysis of three reflectarrays with pencil beam for point-to-point communications, isoflux pattern for global Earth coverage, and a shaped beam for local multipoint distribution service application, showing excellent agreement in both copolar and crosspolar patterns between the SVM and MoM-LP simulations. Finally, the analysis is accelerated by a factor larger than three orders of magnitude using SVMs instead of MoM-LP.

Bandwidth Overlap Factor for Feasible Coexistence of LTE-A and Point to Multipoint LMDS Systems

The necessity to share the radio spectrum becomes highly significant in the recent time due to emerging new wireless technologies and, the cost and difficulty in attaining new frequency spectrum licenses. However, spectrum sharing leads to substantial interference between the close systems especially in the same frequency band. In this paper, we present a spectrum sharing scheme to investigate coexistence feasibility results in interference from orthogonal frequency division multiplexing (OFDM)-based Long Term Evolution-Advanced (LTE-A) into point to multipoint (P-MP) local multipoint distribution service (LMDS). This method proposes a spectrum frequency mask for the OFDM-based LTE-A according to bandwidth overlapping method with the P-MP LMDS system. The relative power spectral density of the proposed spectrum emission mask due to bandwidth overlap has been mathematically derived in a more compact closed-form. It shows smoother and 1.7 dB less than that of traditional OFDM mask in the main spectrum bandwidth which in turn leads to reduce the interference effects to LMDS system. The coexistence coordination studies are made at the frequency of 3500 MHz, on the base of co-primary operation and co-located systems. The numerical results demonstrate that the difference in amount of the required carrier frequency for safe coexistence increases as LMDS sector size increases. In addition, OFDM system with small channel bandwidth is much more affected than the wider channel bandwidth in terms of the necessary minimum guard bandwidth for harmless coexistence when the LMDS cell size changes from 0.5 to 3 km2.

Improved Reflectarray Phase-Only Synthesis Using the Generalized Intersection Approach with Dielectric Frame and First Principle of Equivalence

An improved reflectarray Phase-Only Synthesis technique which employs the generalized Intersection Approach (IA) algorithm is fully described. It is formulated with the First Principle of Equivalence and takes into account a dielectric frame which is usually present to screw the reflectarray breadboard to the supporting structure. The effects of the First Principle of Equivalence versus the Second Principle in the computation of the radiation patterns, as well as the dielectric frame, are assessed and taken into account in an efficient implementation of the generalized IA in order to obtain more accurate results. Different strategies to speed up the synthesis process are presented and to improve convergence. The technique is demonstrated through two examples for space and terrestrial applications: an isoflux pattern for global Earth coverage from a satellite and a Local Multipoint Distribution Service pattern for central stations of cellular systems, both with a working frequency of 25.5 GHz. In addition, experimental results validate the approach described in this work with a prototype with an isoflux pattern working at 30 GHz.

Heterogenous Traffic Performances on Local Multipoint Distribution Service System in Rainy Environment

Local multipoint distribution service (LMDS) system provides high bitrates services up to 40 Mbps operating in millimeter bands. The radio system can be employed to serve heterogenous traffics in any applications such as video surveillance, public internet hotspots and other services. However, the implementation in tropical area faces transmission problems which degrade signal reception, such as heavy rain. This paper examines the performance of heterogenous traffics in LMDS in a rainy environment. Some techniques to tackle rain ploblems were implemented and the effects were assesed. It was proven that PHY and MAC layers contribute to performances enhancement on rainy environment as long as the system uses the suitable scheduler. A packet-based scheduler was proposed by considering packet impact on quality. The results showed that the proposed technique is able to improve video performance about 0.02% over the maximum signal to noise (mSNR) scheduler, maintain voice decoding rate as well as the priority fair (PF) scheduler and increase data decodibility 0.2%.

LTCC Multilayered Substrate-Integrated Waveguide Filter With Enhanced Frequency Selectivity for System-in-Package Applications

This paper presents a cross-coupled bandpass filter with stacked substrate-integrated waveguide cavities on low-temperature cofired ceramic substrates. The proposed filter has a local multipoint distribution service band with a novel same-side-feed input/output structure. Conventionally, a cross-coupled structure generates only a single pair of transmission zeros. The proposed filter can generate two pairs of transmission zeros beside the passband, thereby providing an excellent cutoff rate in the stopband and improved frequency selectivity. The additional pair of transmission zeros is created by the same-side-feed structure, which constructs an additional source-load coupling path without increasing the circuit size. A multipath coupling diagram is used to illustrate the conformation of the second pair of transmission zeros and predict its behavior. The experimental filter exhibits responses centered at 27.95 GHz with an insertion loss of -2.8 dB, and a bandwidth of 9%. Two pairs of transmission zeros (at 26.3 and 29.6 GHz, and at 23.2 and 37 GHz) around the passband were obtained, achieving excellent selectivity and a wide stopband.

Predicting Radio Frequency Radiation from Mobile Communication Base Stations

While the spectrum growth is expected to increase exponentially in the future years to come, the imminent query would be as whether the current spectrum management process is capable of fulfilling all future requirements. Public interest in the potential health issues relating to cellular or mobile communication base station (BS) and other radio communication facilities emphasize the importance of having an accessible and easy to understand information on electromagnetic (EM) and radio frequency radiation (RFR) levels in the surrounding environment. The information is considered critical in order to assess the potential radiation level prior and during the roll-out of planned or future services such as the 4G, Terrestrial Trunked Radio (TETRA), Worldwide Interoperability for Microwave Access (WiMax), Local Multipoint Distribution Service (LMDS) and others. The paper outlines the attempts of developing a specialized software tool that can gauge the RFR concentration within a particular area. The tool encompasses; among many, the capability of facilitating as well as ensuring that the RFR monitoring activities and planning can be carried out efficiently and effectively.

Substrate Integrated Waveguide Quasi-Elliptic Filters With Controllable Electric and Magnetic Mixed Coupling

This paper proposes a type of quasi-elliptic filter with controllable electric and magnetic mixed coupling based on substrate integrated waveguide cavity resonators using two-layer printed circuit board process. For the second-order mixed coupling filter, an embedded short-ended strip line is combined with a conventional inductive window between two cavities to create the mixed coupling, in which the electric and magnetic coupling can be separately controlled by adjusting the width of the strip line and the inductive window, and a controllable transmission zero can be produced below or above the passband. For local multipoint distribution service application, three directly coupled quasi-elliptic filters and two cross-coupled quasi-elliptic filters are designed, simulated, and fabricated using the mixed electric and magnetic coupling second-order filtering units at the Ka-band. For the N-order filter, a maximum of N-1 finite transmission zeros can be realized. The proposed filters show the advantages of good selectivity with controlled transmission zeros, wide upper stopband, and easy integration with other planar circuits. Good agreements have been observed between the measured results and the simulated ones.

A REAL-TIME MULTIMEDIA APPLICATION STUDY IN LMDS NETWORKS USING MPLS

Several wireless networking solutions have been developed to provide different types of services for various end user applications. Due to the success of ATM and IP technology in the information technology area. Local Multipoint Distribution Service (LMDS) is a broadband wireless access (BWA) networking solution. In this paper, an LMDS (Local Multipoint Distribution System) over MPLS (Multi-Protocol Label Switching) network for real-time multimedia applications is introduced. LMDS-MPLS network model is realized and simulated by using OPNET 9.0 simulation package. The simulation results are obtained for sample voice, video, data and non-critical data traffics under varying network load conditions. Analysis of the end-to-end delay results is also presented.

LTCC VERTICALLY-STACKED CROSS-COUPLED BANDPASS FILTER FOR LMDS BAND APPLICATIONS

This study develops a compact 28GHz bandpass fllter on a low-temperature co-flred ceramic substrate for applications in LMDS (Local Multipoint Distribution Service) bands. The fllter comprises two pairs of verticallystacked cross-coupled open loops with vertical interconnection structures, achieving compactness, high integration, and superior frequency selectivity. Attaining selective response with two transmission zeros requires adjusting the couplings of adjacent resonators and external quality factor. The open loops are fed by using the three-via vertical interconnections to prevent any electrical efiect on the fllter. Measurements correlate closely with the simulation results: this study achieved a bandwidth of 2.1GHz (27.6{29.7GHz) with two zeros located at 25.8GHz and 31.1GHz, and a compact size of 2:69 £ 2:66 £ 0:4mm 3 .

Stacked Patch Antenna Array on LTCC Substrate Operated at 28 GHz

This study develops a 28-GHz patch antenna array using LTCC (Low Temperature Co-fired Ceramic) technology, for use in applications of LMDS (Local Multipoint Distribution Service). The design comprises 2 × 2 stacked patch elements and parallel-fed networks, yielding a wide bandwidth and superior gain performance. Broadband performance is achieved by varying the dimensions of the parasitic patch. The arrays are excited through using a novel opposite-side feeding structure to prevent any electrical effect on the parasitic patch. Measurements correlate closely with the simulation results: a gain of 10.35 dBi and a bandwidth of 2.85 GHz (26.75–29.6 GHz) are achieved.

FUZZY WEIGHT CONTROLLER BASED CELL-SITE DIVERSITY FOR RAIN FADING MITIGATION IN LMDS NETWORKS IN THE TROPICS

Local multipoint distribution service (LMDS) is a broadband wireless access technology that operates at microwave frequencies above 25GHz. However, severe attenuation due to excessive rain in tropical regions presents a major challenge for achieving reliable communication over such frequencies. To overcome this problem, cell-site diversity (CSD) can be deployed in cellular- type LMDS networks. In this paper, we address the problem of reliable communication for LMDS networks in heavy rain regions by proposing a fuzzy weight controller based cell-site diversity (FWC- CSD) scheme. Rain cells are randomly simulated in an LMDS network to analyze the system performance using the proposed FWC-CSD scheme. Simulation results show that the proposed scheme yields improved performance in terms of average outage probability and throughput while maintaining the overall quality of service.

측파대 광 주입 락킹 기법을 이용한 밀리미터파 신호생성 및 실험적 분석

본 논문에서는 밀리미터파 대역의 신호 발생을 위한 헤테로다인 방식인 sideband injection locking 방법을 제안하고 실험적으로 분석하였다. 향후, 무선 이동통신, 초고속 광대역 통신망 등에 사용되어질 밀리미터파 신호는 전기적 요소의 한계로 광학적인 요소에 의해 신호를 생성하는 방법이 많이 연구되고 있으며 광학적 기술에 기초한 소자기술 등이 발전되고 있다. 따라서 본 논문에서는 향후 밀리미터파 대역에서 사용되어질 LMDS(Local Multi-point Distribution Service) 등의 시스템에서 수십기가 헤르츠급의 광원으로 응용 가능한 헤테로다인 방식을 이용한 밀리미터파 대역의 신호생성에 대한 이론적 방법 및 실험적 고찰을 통하여 검증하였다. In this paper, we have proposed sideband injection locking method, heterodyne technique, to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase-array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of tens of GHz applicable to LMDS. We experimented and analysed the generation of millimeter wave signal.

Design of LTCC Wideband Patch Antenna for LMDS Band Applications

This letter presents a wideband patch antenna on a low-temperature cofired ceramic substrate for Local Multipoint Distribution Service band applications. Conventional rectangular patch antennas have a narrow bandwidth. The proposed via-wall structure enhances the electric field coupling between the stacked patches to achieve wideband characteristics. We designed same-side and opposite-side feeding configurations and report on the fabrication of an experimental 28-GHz antenna used to validate the design concept. Measurements correlate well with the simulation results, achieving a 10-dB impedance bandwidth of 25.4% (23.4-30.2 GHz).

Secure communications in local multipoint distribution service (LMDS) networks

The transmission of confidential information over LMDS networks is investigated in the present paper from an information-theoretic standpoint. The major factor impairing the link performance at these networks is rain attenuation, a physical phenomenon exhibiting both spatial and temporal variation. Based on an accurate channel modeling, analytical expressions of the probability of non-zero secrecy capacity and the outage probability for this type of networks are provided, giving for the first time an information-theoretic approach of the problem of secure transmission for LMDS networks. Useful conclusions are drawn through extended numerical results suggesting the increase of operational frequency and the use of more directional antennas to improve security in transmission of confidential messages for this type of networks.

Voice Operated Guidance Systems for Vision Impaired People: Investigating a User-Centered Open Source Model

Many wireless networking systems were established to manipulate metropolitan networks in order to provide internet, voice, data, video and TV services in large cities. Two major systems were used for such services; Local Multipoint Distribution Service (LMDS) and Multi-channel Multipoint Distribution Service (MMDS). Both of these systems are fixed broadband access networks and both have problems in the cost, speed, coverage area and last-mile bottleneck, especially when the network size is increased. Deploying a new technology of a Wireless Optical Mesh network (WOMN) which uses wireless optical communications between nodes can overcome these problems and can provide more bandwidth, an interference-free network, a frequency-free network, and more effective applications that require a real time responding like video surveillance. We investigate the WOMN against LMDS and MMDS to show that WOMN is better than both LMDS and MMDS in commercial, geographical coverage, and real time applicability. We will also investigate the challenges to deploy the new technique for local and metropolitan networks between different city buildings. Furthermore, we will show that we can have a better performance by including microwave weather detection mechanism through the estimation of the fog and rain presence under several different conditions. In addition, combining the Free Space Optic (FSO) technology with the 60GHz radio waves can increase the WOMN link availability, thus providing an alternative communication way and increasing the distance between wireless optical devices. This strategy can avoid the effect of fog and snow on wireless signal since they do not have effect on the propagation of 60GHz radio waves. The WOMN link can be engineered by adjusting antenna size, choosing a high-power option, and changing the microwave frequency.

FADE MARGINS PREDICTION FOR BROADBAND FIXED WIRELESS ACCESS (BFWA) FROM MEASUREMENTS IN TROPICS

The fade margins for 15, 23, 26 and 38GHz frequency bands are predicted based on one-minute rain rate measurements for four years at Universiti Teknologi Malaysia (UTM) Skudai and the speciflcations of the given four MINI-LINKS. The availabilities of terrestrial microwave links are also investigated based on rain attenuation data collected from seven operational microwave links at 15GHz and one at 23GHz for more than one year. The fade margins for all eight links are measured based on the rain attenuation data collected with difierent hop lengths. In this paper, the feasibility to design outage-free wireless broadband radio link also highlighted. These results will contribute to the better design of outage-free Broadband Fixed Wireless Access (BFWA) system such as, Local Multipoint Distribution Service (LMDS) and IEEE802.16 in tropical regions.

SIMULATION MODEL FOR COMPATIBILITY OF CO-SITED IMT-ADVANCED AND POINT TO MULTIPOINT SERVICES

GHz fixed wireless access system is a point-to- multipoint wireless technology providing broadband services. In this paper, point-to-multipoint fixed cellular service network structure such as Local Multipoint Distribution (LMDS) service is proposed to share same network area and frequency band (3400-3600 MHz) with the fourth generation of mobile (IMT-Advanced) represented by mobile Worldwide Interoperability for Microwave Access (WiMAX) service on base of co-sited systems. As a result of space and frequency domain sharing, harmful interference probability may be transpired between the two services. Different network cell sizes and different channel bandwidths were considered in dense urban area to investigate the intersystem interference effects based on the average interference to noise ratio INR as a fundamental criterion for coexistence and sharing coordination between different systems. Adjusting of antenna discrimination loss is also proposed to facilitate the frequency efficiency and accomplish frequency sharing.