Microwave Radio Links Research Articles

Characterization of microwave fading over coastal cities of Nigeria

Atmospheric meteorological parameters (relative humidity, atmospheric pressure, and temperature) are unique due to the constant difference between them. This paper characterizes the fading associated with the microwave radio signals based on 10 years (2006 to 2015) re-analyzed data at 00 hours local time (LT), 06 hours LT, Noonday, and 18 hrs LT (synopsis hours) over seven (7) Coastal cities in Nigeria (Port-Harcourt, Warri, Calabar, Arogbo, Oron, Yenagoa and Lagos Island). The reanalysis data was obtained from the European Center for Medium-Range Weather Forecasts (ECMWF) at a resolution of 0.25 by 0.25 resolutions in the selected cities. Radio Refractivity (RR), Radio Refractivity Gradient (RRG), Point Radio Refractivity (PRR), and Geoclimatic Factor (GF) are obtained from the data. Fade Depth Percentages Exceedance (FDPE) that occurred at the study locations were deduced to determine the level of signal degradation at the microwave radio links over the coastal regions of Nigeria.

Review of optical and wireless backhaul networks and emerging trends of next generation 5G and 6G technologies

AbstractMobile Backhauling provides an interface between radio controller and base stations, mostly realized with a physical medium such as optical fibers or microwave radio links. With the huge mobile traffic due to an increase in mobile subscribers as well as deployment of 4G and 5G cellular network technologies, better solutions for capacity and coverage should be provided in order to enhance spectral efficiency. For 4G cellular networks, mobile backhaul networks deal with capacity, availability, deployment cost, and long‐distance reaches. In addition, mobile backhaul networks based on the 5G network incurs additional challenges that include 1 ms or less ultralow latency time requirements and ultra‐dense nature of the network capabilities. Therefore, for 5G technologies, latency delay, QoS, packet efficiency, noise suppression, and mitigation techniques, efficient modulation schemes, and packet network timing synchronization are some aspects that are to be dealt with while designing efficient backhaul approaches (wired/wireless). Current backhaul systems typically use cost‐effective solutions (eg, ‐Wi‐Fi and WiMAX)‐based packet‐switched technologies, especially Ethernet/Internet technologies and high‐speed optical fiber links.

Modelling of Alpha and Beta for Rain Rate Prediction for Radio Propagation Systems

The effect of rain in the design of satellite and terrestrial microwave radio links is of interest to Engineers and Scientists. It is good to have a reliable design that guarantees high level of accuracy of the rain rate distribution from the lowest rain rate value to the highest. The present work proposes a model that expresses rain rate as a function of alpha and beta obtained at 0.01% of time. When tested, the results obtained with the measurement perform well for the stations considered at a rain rated between 5mm/h to 200mm/h. Thus, , the empirical models that were obtained through them could be a useful tool for the radio design engineers for high rain rate areas.

Radiolink Microwave Sebagai Infrastruktur Telekomunikasi Sistem SCADA

Expansion of the electrical network and substation makes a demand of the telecommunication channel for SCADA system is high. Telecommunication infrastructure which operates based on Power Line Carrier (PLC) can not provide adequate supply. Therefore, It needs new media to fulfill the demands of the telecommunication channel for SCADA System. Selection methods will be done by comparing technical and non-technical aspects of various telecommunication media that operates in the PLN network. One of suitable media is microwave radiolink. With high capacity and bandwidth, microwave radiolink can be the backbone of SCADA System

Performance Analysis of the Impact of Rain Attenuated Signal on Mobile Cellular Terrestrial Links in Jos, Nigeria

The 12 to 18 GHz frequency bands are commonly deployed for mobile network metropolitan microwave radio links using small antennas and low transmit power to deliver high channel capacities. Jos Plateau region with the blend of tropical and temperate climate is characterized with high severe rain impairment on terrestrial links operating at frequencies above 10 GHz, for mobile network backhaul system remaining a big challenge in the design of a microwave radio link. Therefore, this study presents the performance analysis of the impact of rain attenuated signal on mobile cellular terrestrial links in Jos under clear sky and rain condition. The cell site locations were divided in two clusters of Jos lowland and Jos highland. Drive test tools, radio local monitor terminal (LMT) and Davis weather station were employed over radio links interconnecting live 2G/3G nodal network, for the measurement of the mean value of one minute rainfall rates and the corresponding rain-induced signal. The results obtained revealed that more budget provision was obtained by the study calculation in over 60% of the study centers. More so, when the study fade margin estimation was put to test, up to 4.27 Mbps download speed was achieved, the speed almost as high as the highest speed, 4.29 Mbps recorded under the clear sky for ITU-R. More so, as low as 0.7% packet loss was recorded against the study link margin budget under same rain condition causing over 62.3% for PLA010 in Jos lowland cluster. Also, instances of slight under-budgeting were observed in highland clusters PLA064 and PLA025 as 35.01 dB and 34.99 dB respectively when tested with the Study calculated values.

Excess Attenuation Caused by Antenna Wetting of Terrestrial Microwave Links at 32 GHz

Excess attenuation of microwave radio links caused by the wet antenna effect is addressed. Long-term measured attenuation of two commercial microwave links (816 m 611 m long) at 32 GHz is compared to theoretically predicted rain attenuation. The theoretical prediction is calculated using a kRα relationship where k and α are constants derived from a local disdrometer measurement, and rain rate R is available from rain gauges placed at both ends of the links to obtain the distribution of rain rate along the path length. From this comparison, excess attenuation caused by antenna wetting is derived. A new model describing wet antenna attenuation (WAA) as a function of rain rate is suggested where excess attenuation reaches approx. 3 dB per antenna for a rain rate of 100 mm/h. Statistics of theoretically predicted rain attenuation, including the WAA term, is compared with statistics of measured attenuation on a set of three other links working at the same frequency. Adding the wet antenna term to the rain attenuation calculation significantly improves the accuracy of the rain attenuation prediction.

Rain Rate Distributions for Microwave Link Design Based on Long Term Measurement in Malaysia

Attenuation due to rain is an important constraint in microwave radio link design especially at frequencies above 10 GHz. It restricts the path length of radio communication systems and limits the use of higher frequencies for line-of-sight microwave links and satellite communications. In order to predict the attenuation due to rain accurately rainfall intensity is required with 1-minute integration time. Rainfall is a meteorological phenomenon with complex structure due to its variability in space, duration and occurrence frequency, particularly in tropical and equatorial regions. Since, the statistical distribution of rain attenuation is obtained from the rain rate distribution for the region considered, it should be noted that the accuracy of the rain rate measurement affects the accuracy of the attenuation estimation. This paper presents rain intensity with 1-minute integration time measured for 6 years in Malaysia, it’s distribution, comparison with other prediction models and impact on high frequency microwave links.

Reduced complexity Kalman filtering for phase recovery in XPIC systems

Reduced-complexity Kalman-based algorithms are proposed to recover the phase of cross-polar interference cancellation (XPIC) receivers in microwave radio relay links. In particular, two completely independent radio frequency (RF) transceiver chains are considered for the two different polarizations, in order to have the maximum flexibility to connect different single carrier transceivers to dual-polarized antennas. A one-state Kalman model is proposed, which is of low complexity and thus suitable for a modern higher data rates M-ary quadrature amplitude modulation (M-QAM) receiver. Moreover, a further reduced complexity version is developed that uses a lower amount of information to recover the phase at the receiver, as well as a downsampling procedure to speed up the Kalman algorithm, and an alternative error computation that is essential to ease the Kalman implementation. It is worth noting that the three last simplifications are general and can be applied not only to a one-state Kalman model. Simulation results compare the proposed simplified Kalman solutions to typical phase-locked loop (PLL) algorithms proving their comparable performance with the benefit of lower complexity. Finally, the relationships between the Extended Kalman and the PLL approaches are investigated. The obtained relation is essential for the cross-polar phase recovery, since, as far as the authors know, there are not closed-form solutions for the PLL parameter optimization in cross schemes.

The organization of the information superhigh frequency channel in the middle of the action resistant to fading signal

Reviewed and analyzed issues related to the organization of duplex radio ultra high frequency (UHF) band for exchanging information between a vehicle (the vehicle) and a ground station. Presents a methodology for selecting the transmitting-receiving horn antennas, carried out energy calculation of microwave radio links. Will sirovina the interference information of the microwave channel in the middle of the action to the fading signal for coherent reception. It is shown that in the conditions of fading of the microwave signal, the probability of error can reach at least 10 -6 ...10 -8 on the sign.

Propagation at mmW Band in Metropolitan Railway Tunnels

The next generation of mobile communications, 5G, will provide a wideband network based on microwave and millimeter‐wave (mmW) communication radio links with the goal of fulfilling the strict and severe requirements of the future test cases. In particular, this paper research is focused on mmW bands in metropolitan railway tunnels. For that purpose, a propagation measurement campaign was performed at 24 GHz band in a passenger train on a realist subway environment, and these results were combined with simulations ad hoc for tunnels and a theoretical modal propagation model. A narrowband and a wideband study have been conducted with the aim of obtaining the path loss, fading, power‐delay profile, and angle of arrival, taking into consideration horizontal and vertical polarization in the receiving and transmitting antennas. This validation can be used to design and deploy wideband mobile communication networks at mmW bands in railway scenarios.

THE RESEARCH OF TRANSMISSION OF DVB-C TELEVISION SIGNALS BASED ON THE PROTOTYPE OF TRANSCEIVER OPERATING IN THE LOWER PART OF TERAHERTZ BAND

Background. Currently digital microwave radio relay links operating in centimeter bands and in the lower part of millimeter bands (3.4 - 40.5 GHz) are widely used in the leading countries to construct their telecommunication infrastructure. Taking into account the lack of spectrum in these frequency bands and growing necessity to transmit high-rate applications with the help of brand-new radio relay equipment of the world leading manufacturers of such equipment, tendency to operate in higher parts of millimeter bands is becoming more real and practicable. At the same time, the terahertz band (100-3000 GHz) which is not used at the present time (because of complexity of construction of radio relay equipment that could operate in this band) isalso very perspective for introduction of the future radio relay equipment (for the reason of high information capacity of 100-3000 GHz band). The Research Telecommunication Institute of the National Technical University of Ukraine and the Institute of Electronics and Communications of the Ukrainian Academy of Science developed the prototype of the transceiver for operation in the lower part of the terahertz band (130-132 GHz band). For this reason there was a necessity to conduct research concerning operation of the prototype in 130-132 GHz band (that is to test quality of operation of separate blocks of transceiver by changing parameters of transmitting signals passing through it).Objective. The purpose of the research is the parameters variation of multichannel digital broadcasting TV signals based on DVB-C standard when TV signal is transmitted through the 130 GHz transceiver prototype. DVB-C standard has been chosen for this research to have opportunity to analyze signals with different modulation schemes (from QAM-64 to QAM-256), which allowed investigating the influence of certain prototype node parameters on the signal parameters that were transmitted through itMethods. To conduct the research the experimental installation has been constructed with several parts in it (transceiver, subsystem for generation of DVB-C television signals, subsystem for measurement of DVB-C television signal parameters). The research has been conducted in three stages using a step-by-step approach with application of one-channel, two-channel andthree-channel signals of DVB-C standard.Results. Results of the research showed that the use of the transceiver (that has common heterodyne for transmitting and receiving parts) in the lower part of terahertz band (130 GHz) permits to transmit three TV broadcasting channels of DVB-C standard in 24 MHz bandwidth with transmission rate of 125 Mbit/s with high subjective quality of all TV programs.Conclusions. The results of the research demonstrated high quality of digital TV signals transmission by means of transceiver constructed for application in terahertz band (130-132 GHz). The reason for such conclusion is that harmonic distortions have not been observed and phase noise of heterodyne has not led to significant channel symbols distortion on signal constellation. The next step in future research will include the research of the quality of DVB-C signal transmission for cases when terahertz radio link is used and specific heterodynes are applied in transmitting and receiving parts of the transceiver prototype. In the future the transceiver can be used for construction of digital microwave radio relay links in terahertz band for transmission and reception of digital TV signals with high rate both for broadcasting and other applications such as Internet.

A comprehensive comparison between GaN MMIC Doherty and combined class-AB power amplifiers for microwave radio links

A combined class-AB and a Doherty power amplifier conceived for microwave backhaul in the 7 GHz frequency band are here presented and compared. They are fabricated in the same GaN monolithic process and have identical total active device periphery. For the given application, the linearity-efficiency trade-off for the two architectures is discussed. The two modules have been thoroughly characterized in linear and non-linear continuous wave conditions. Then, to evaluate linearity under the actual operative conditions, a system level characterization has been carried out, applying a modulated input signal and comparing the spectral responses of the two amplifiers with and without digital predistortion. A saturated output power of 40 dBm has been achieved by both circuits. At 6 dB of output back-off, the Doherty amplifier shows an efficiency of 33%, 10 points higher than that of the class-AB module. On the other hand, system level measurements show that, adopting the same predistorter complexity to comply with the reference standard emission masks, the Doherty amplifier needs at least 1 dB of extra back-off. This negatively affects its efficiency, therefore reducing the advantages it can claim with respect to the class-AB amplifier in continuous wave condition.

CUMULATIVE DISTRIBUTIONS OF RAINFALL RATE OVER SUMATRA

The microwave radio links above 5 GHz suffer from attenuation due to precipitation. The need for employing higher frequencies has therefore encouraged research into rain attenuation due to precipitation. The natural variations of tropical precipitation occur in a wide range of time-scales, so does probably the behavior of radio communication links. This paper examines the variations of cumulative distribution of rainfall in Sumatra from an optical rain gauge measurement with a near continuous record of operation over eleven consecutive years (2002-2012). The worst month statistics were also examined and all results were compared with the ITU-R model. Of some natural variations of rainfall rate investigated, the diurnal variation had the most significant effect on the cumulative distribution of rainfall rate. The ITU-R model overestimated the rainfall rate for the first half of the day (00:00-11:59 LT) whereas it underestimated the rainfall rate until 0.01% of time for the second half of the day (12:00-23:59 LT) before the model starts to overestimate. The ITU model overestimated 52.85% of rainfall rate at 0.01% of time for the first half of the day and underestimates 7.59% for the second half. Considerable differences between the recorded data and the ITU-R model for the annual, seasonal, and intreaseasonal variations are only significant at small time percentage (≤ 0.01%). The relationship of worst month statistics was also slightly different from the ITU-R model. This result reinforces the previous studies on the limitation of the ITU-R model for the tropical region.

Method for avoiding near-field effects of wind turbines on microwave terrestrial radio links

Potential impact of wind turbines on telecommunication services is an increasing concern in wind farms deployment. The evaluation of the potential disturbance of a planned wind farm requires accurate and unbiased criteria applied in a comprehensive impact study. Near-field effects of wind turbines on microwave radio links is one of the less analyzed disturbances. In this article, new theoretical-based criteria and an easy to apply step-by-step calculation procedure are proposed. Results of the method are in the form of constraint masks, easy to apply by wind farm promoters in the layout design, by telecommunications operators in the evaluation of the potential impact, and by administrations involved in license tasks. In the article, the proposed method is applied to real cases of wind farms located close to radio links facilities and compared to current criteria.

장거리 무선 링크의 가용도 보장을 위한 적응전송 기법

In Microwave Radio Link, it is necessary to consider the radio fading to consistently assure the radio link of the high quality as the distance. If the fixed modulation is used for the microwave radio link, it is difficult to keep the high availability of link for the case of the long distance. Adaptive Modulation(AM) provide good quality on microwave link, but the application of the only-AM is not enough to provide the availability assurance due to the fluctuating characteristics of link capacity. Our previous study has proposed the improvement method of transmission in association with the distance, however the previous method needed to make up for the common application. There was no suggestion of a mathematical formula with a variable. In this paper, we propose an optimized Adaptive Transmission Techniques with calculating formula of the priority traffic transmission capacity based on AM in consideration of the fade margin for the availability assurance as the distance and the comparison of the channel bandwidth for Long-distance Radio Link.

Internet Access Using Ethernet over PDH Technology for Remote Area

There was still is gap among people living in city and in remote area to get information access, especially who lived in the Eastern part of Indonesia. People living in such remote area usually were isolated from town by natural condition like rivers, valleys, hills and so on.. Therefore, telecommunication infrastructure for remote area using cooper was not effective and efficient way to build. The issue was how information and communication technology could penetrate such areas. This research aimed to propose technology that could be implemented to overcome the difficulties. Ethernet over Plesiochronous Digital Hierarchy (EoPDH) was one of many techniques that provided Ethernet connectivity over non-Ethernet networks. EoPDH was a standardized methodology for transporting native Ethernet frames over the existing established PDH transport technology. To provide last milefor the local people, use of Mesh Wireless Local Area Network was made and connected to internet gateway via Ethernet over PDH based microwave radio link. The test showed that The Ethernet frames were successfully transported to remote area with good quality of service such as throughput, response time, and transaction rate.

Estimation of Effective Transmission Loss Due to Subtropical Hydrometeor Scatters using a 3D Rain Cell Model for Centimeter and Millimeter Wave Applications

The problem of hydrometeor scattering on microwave radio communication down links continues to be of interest as the number of the ground and earth space terminals continually grows The interference resulting from the hydrometeor scattering usually leads to the reduction in the signal-to-noise ratio (SNR) at the affected terminal and at worst can even end up in total link outage. In this paper, an attempt has been made to compute the effective transmission loss due to subtropical hydrometeors on vertically polarized signals in Earth–satellite propagation paths in the Ku, Ka and V band frequencies based on the modified Capsoni 3D rain cell model. The 3D rain cell model has been adopted and modified using the subtropical log-normal distributions of raindrop sizes and introducing the equivalent path length through rain in the estimation of the attenuation instead of the usual specific attenuation in order to account for the attenuation of both wanted and unwanted paths to the receiver. The co-channels, interference at the same frequency is very prone to the higher amount of unwanted signal at the elevation considered. The importance of joint transmission is also considered.

Using Microwave Backhaul Links to Optimize the Performance of Algorithms for Rainfall Estimation and Attenuation Correction

Abstract The variability in raindrop size distributions and attenuation effects are the two major sources of uncertainty in radar-based quantitative precipitation estimation (QPE) even when dual-polarization radars are used. New methods are introduced to exploit the measurements by commercial microwave radio links to reduce the uncertainties in both attenuation correction and rainfall estimation. The ratio α of specific attenuation A and specific differential phase KDP is the key parameter used in attenuation correction schemes and the recently introduced R(A) algorithm. It is demonstrated that the factor α can be optimized using microwave links at Ku band oriented along radar radials with an accuracy of about 20%–30%. The microwave links with arbitrary orientation can be utilized to optimize the intercepts in the R(KDP) and R(A) relations with an accuracy of about 25%. The performance of the suggested methods is tested using the polarimetric C-band radar operated by the German Weather Service on Mount Hohenpeissenberg in southern Germany and two radially oriented Ku-band microwave links from Ericsson GmbH.

Performance Measures of Tele-Protection System Based on Networked Microwave Radio Link

The purpose of paper is to compute reliability of Digital Tele-Protection System employing Digital Microwave Radio Link. In this paper, the whole Tele- Protection system is divided into six subsystems. The first subsystem is digital relaying equipment. Second subsystem is the tale-protection signaling equipment where the timing to sample line power currents is synchronized. Both relaying and Tele-Protection signaling equipments, are now assemble three-phase current data, sampled at 600 Hz for 50 Hz EHV systems and some control data into a 90 bit frame format at a transmission rate of 54 Kb/s. A frame consists of a frame synchronization field and some information fields including a cycle's redundancy check field. The third subsystem, Tele-Protection signed multiplexing equipment generates a super frame by multiplexing the seven, 54 Kb/s Tele-Protection signals into a 1.544 Mb/s stage using multi-point sampling technique to minimize the delay time variation and send them to the subsystem four, which is radio equipment, from here the data is transmitted with the help of the channel (subsystem 5) to the repeater station (subsystem 6). The subsystem six is used to remove the noise and to improve the power of the data. In this paper, we have taken standby digital relaying equipment and that can be online through an imperfect switching device. Also parallel redundant Tele-Protection signaling equipment is taken to improve system's overall performance.

Metallic Compound Air-Fed Array Antennas for Cost-Effective Microwave Radio-Link Applications

A novel structure of metallic compound air-fed array (M-CAFA) antennas, as one kind of improved Fabry-Perot resonator (FPR), is proposed in this letter. With a stepped metallic ground plate, metallic grating cover, and open-ended waveguide as the feeder, this antenna exhibits the merits of low profile, low cost, and easy integration onto outdoor unit of microwave radio-link. Its operation principle, simulation analysis, and design procedure are presented. Also, an experimental prototype of around 13 GHz is fabricated with measured results as peak gain (directivity) of 19.2 dBi, common bandwidth of 3.85% for both 3-dB gain-drop and VSWR ≤ 1.5:1, and good radiation characteristics.