Terrestrial Links Research Articles

Experimental Validation of a High Precision GNSS System for Monitoring of Civil Infrastructures

In recent years, Global Navigation Satellite System (GNSS) technologies, which take full advantage of both real-time kinematic (RTK) and precise point positioning (PPP), managed to reach centimeter-level positioning accuracy with ambiguity resolution (AR) quick convergence techniques. One great advantage over traditional structural health monitoring (SHM) systems is that GNSS technologies will be functional in disaster management situations, when terrestrial communication links become unavailable. In this study, a multi-GNSS system, based on GPS and Galileo constellations and exploiting advanced RTK and PPP-AR technologies with update rate of 100 Hz is tested on two benchmark structures as an SHM system. The first case study served as a baseline to outline the methodology: first, a setup phase of the instrumentation, then a signal processing phase and last, the validation of the results. The methodology was then applied to a real-case scenario, in which the GNSS was tested on a road bridge. A comparative analysis with the results acquired by a set of accelerometers showed that the GNSS was able to identify the crossing of heavy vehicles. The work is paving the way for the development of an affordable and efficient multi-GNSS-based tool for the monitoring of civil infrastructures.

Performance analysis of 400 Gbit/s hybrid space division multiplexing‐polarization division multiplexing‐coherent detection‐orthogonal frequency division multiplexing‐based free‐space optics transmission system

SummaryA high‐capacity free‐space optics‐based terrestrial communication link using spectral‐efficient space division multiplexing and polarization division multiplexing techniques has been proposed in this research work. Orthogonal frequency division multiplexing with the use of coherent detection has been proposed for the transmission of quadrature amplitude modulated high‐speed signals. Eight independent 50‐Gbit/s data streams are transported by two orthogonal polarization states (X and Y) of four distinct Hermite–Gaussian spatial modes to increase the transmission rate of the link to 400 Gbit/s over a single channel. Through numerical simulations, we report feasible transportation of 400‐Gbit/s information at 10 km under clear weather with faithful performance. Further, the impact of atmospheric scintillation and fog weather has been evaluated using simulations. The results report that the maximum range reduces to 6 km under clear weather in the presence of strong atmospheric scintillation. Moreover, the maximum range of 2000, 1700, and 1300 m is reported for light, moderate, and heavy fog conditions respectively.

Conversion of 15-Minutes to 1-Minute Rainfall Distribution Derived from Tropical Rainfall Distribution Measurement

The radiocommunication sector of the International Telecommunication Union (ITU R) necessitates a 1-min integration time of rainfall rate to predict attenuation at terrestrial links and earth-space links. Since time series of rainfall that satisfies this requirement is not common, the conversion into corresponding 1-min distribution is suggested as an alternative of time series with longer integration time, T (e.g., 10-,30-,60-minutes). This research reviews existing methods for the conversion of cumulative distributions of rainfall and compares the said conversion methods. Several approaches are utilized to convert the 15-minutes rainfall rate to a 1-min rainfall rate in the tropical area of Kampung Paya Jaras. It found that Segal’s method performs the best conversion procedure overall.

Mega-Constellation Design for Integrated Satellite-Terrestrial Networks for Global Seamless Connectivity

In this letter, we study the integrated satellite-terrestrial network where users can access the core network by the backhaul links via both multi-layer satellites in the space and terrestrial access points on the ground. The mega-constellation design for such an integrated satellite-terrestrial network is investigated to realize the global seamless connectivity and provide high-rate backhaul transmission. First, we propose a theoretical framework for the average uplink capacity analysis. Second, based on the developed theoretical framework, we design a mega satellite constellation given the capacity of terrestrial backhaul links for realizing the global connectivity with the minimum satellite number. Simulation results show that as the terrestrial infrastructures are distributed more evenly in latitude, the designed mega-constellation first requires more satellites and then remains unchanged regardless of the terrestrial transmission capacity of high-latitude user terminals.

Secrecy Outage Analysis of Relay-User Pairing for Secure Hybrid Satellite-Terrestrial Networks

In this paper, we study the physical-layer security of a hybrid satellite-terrestrial network composed of a satellite, multiple terrestrial decode-and-forward (DF) relays and users in the presence of a terrestrial eavesdropper who attempts to tap legitimate information from both satellite and relays. We consider two different scenarios: I) the channel state information (CSI) of wiretap links is known, and II) the CSI of wiretap links is unknown. Accordingly, optimal and suboptimal relay-user pairing schemes are proposed for the aforementioned two scenarios, respectively. Specifically, a relay-user pair maximizing the secrecy rate is chosen as the optimal one to participate in the transmission, where all links’ CSI is used to perform relay-user pairing. However, suboptimal relay-user pairing scheme is designed only relying on the main links’ CSI without requiring wiretap links’ CSI, where a relay-user pair with the maximal transmission rate of main link is selected. Also, closed-form expressions of secrecy outage probability with both integer and rational fading severity parameter are derived in the case of satellite links undergo Shadowed-Rician fading and terrestrial links subject to Rayleigh fading. Furthermore, asymptotic secrecy outage probability analysis is conducted in the high signal-to-noise ratio region. Numerical results reveal that relay-user pairing is beneficial to further improve physical-layer security of the hybrid satellite-terrestrial network.

Optimalisasi Saluran Komunikasi Berbasis Gelombang Mikro Sebagai Alternatif Sistem Pemantauan Curah Hujan

As a vast archipelagic country with diverse topographic conditions and has an annual average rainfall of more than 2000 mm, Indonesia is prone to hydrometeorological disasters. Based on Indonesia's disaster data, throughout 2021 there were 3,658 incidents of floods and landslides distributed throughout Indonesia. This makes real-time rainfall monitoring with high density indispensable. Indonesia currently has a rainfall monitoring system about 1000 automatic rain gauges, so an increase in the spatial resolution of network is necessary. The increasing density of monitoring equipment using rain gauges and weather radar poses the problem of high procurement and operational costs. Therefore, several alternative rainfall monitoring systems are needed. In this article, we review several studies that focus on the utilization of terrestrial and satellite communication link operating in high frequency bands as an alternative for measuring rainfall. Optimization of the satellite communication system network is more suitable than terrestrial networks to be applied in Indonesia with archipelagic areas because it has a large number of point distributions with wider coverage. The use of artificial intelligence with deep learning techniques such as one dimensional convolutional neural network (1D-CNN) is also very promising to estimate rainfall intensity because it has a high accuracy of 93%..

Natural versus anthropogenic controls on the dissolved organic matter chemistry in lakes across China: Insights from optical and molecular level analyses

Dissolved organic matter (DOM) plays an essential role in the global carbon biogeochemical cycle for aquatic ecosystems. The complexity of DOM compounds contributes to the accurate monitoring of its sources and compositions from large-scale patterns to microscopic molecular groups. Here, this study demonstrates the diverse sources and compositions for humic-rich lakes and protein-rich lakes for large-scale regions across China with the linkage to optical components and molecular high-resolution mass spectrometry properties. The total fluorescence intensity of colored DOM (CDOM) for humic-rich lake regions (0.176 Raman unit; R.U.) is significantly (p<0.05) higher than that of the protein-rich lake region (0.084 R.U.). The combined percentages of CDOM absorption variance explained by the anthropogenic and climatic variables across the five lake regions of Northeastern lake region (NLR), Yungui Plateau lake region (YGR), Inner Mongolia-Xinjiang lake region (MXR), Eastern lake region (ELR), and Tibetan-Qinghai Plateau lake region (TQR) were 86.25%, 82.57%, 80.23%, 88.55%, and 87.72% respectively. The averaged relative intensity percentages of CHOS and CHONS formulas from humic-rich lakes (90.831‰, 10.561‰) were significantly higher than that from the protein-like lakes (47.484‰, 5.638‰), respectively. The more complex molecular composition with higher aromaticity occurred in the humic-rich lakes than in the protein-rich lakes. The increasing anthropogenic effects would significantly enhance the sources, transformation, and biodegradation of terrestrial DOM and link to the greenhouse gas emission and the carbon cycle in inland waters.

Distributed User Association With Grouping in Satellite–Terrestrial Integrated Networks

The satellite–terrestrial integrated network (STIN) has been envisioned as an emerging architecture to provide global anytime anywhere network access, and satisfy transmission requirements of high-capacity backhaul data. However, the integration of satellite and terrestrial networks will aggravate the diversity of base stations (BSs) in backhaul delay and capacity, as well as coverage area, which makes it difficult for users with diverse requirements to access the most suitable service BS. As an effort to address the above problems, a distributed user association with grouping (DUAG) mechanism is proposed via the interaction between BSs and users to maximize the sum rate and balance the load of STIN while meeting the user’s demand by user grouping. First, the transmission characteristics of terrestrial and backhaul links are analyzed after constructing a STIN model, which consists of satellite, three types of BSs, and the variety of intelligent terminals. Then, the user association problems are formulated to maximize the sum rate and balance the load of STIN via jointly considering the backhaul capacity of BSs and mobility and delay of users. Meanwhile, the DUAG mechanism is proposed to associate users with the most suitable service BSs. In DUAG, a greedy-based user association algorithm with user grouping is developed for maximizing the sum rate via giving priority to users with high data rate, and a matching algorithm with user grouping is designed for balancing the load by means of performing multiple iterations between users and BSs. Simulation results demonstrate that the proposed DUAG can maximize the sum rate and balance the load of STIN while guaranteeing the delay demand of user with the increase of user density.

Outage Performance of Multi-UAV Relaying-Based Imperfect Hardware Hybrid Satellite-Terrestrial Networks

In this paper, we consider an imperfect hardware hybrid satellite-terrestrial network (HSTN) where the satellite communication with a ground user equipment (UE) is aided by the multiple amplify-and-forward (AF) three-dimensional ($3$D) mobile unmanned aerial vehicle (UAV) relays. Herein, we consider that all transceiver nodes are corrupted by the radio frequency hardware impairments (RFHI). Further, a stochastic mixed mobility (MM) model is employed to characterize the instantaneous location of $3$D mobile UAV relays in a cylindrical cell with UE lying at its center on ground plane. Taking into account the aggregate RFHI model for satellite and UAV relay transceivers and the random $3$D distances-based path loss for UAV relay-UE links, we investigate the outage probability (OP) and corresponding asymptotic outage behaviour of the system under an opportunistic relay selection scheme in a unified form for shadowed-Rician satellite links' channels and Nakagami-\emph{m} as well as Rician terrestrial links' channels. We corroborate theoretical analysis by simulations.

Physical Layer Security in Cybertwin-Enabled Integrated Satellite-Terrestrial Vehicle Networks

In this paper, we investigate the secure vehicle communications in cybertwin-enabled integrated satellite-terrestrial networks, where the digital twins (DTs) in the cybertwin space reflects the physical entities (i.e., satellite, terrestrial base station (BS), and vehicles). Particularly, considering the channel similarity between different satellite links versus the randomness difference in terrestrial links, it is challenging to reach the secure transmission in satellite and terrestrial links independently with limited resources. Considering the information exchange in the cybertwin space can support an information sharing between such physical entities, the secure transmission design by using the heterogeneous satellite-terrestrial resources can be conducted from a global perspective. With the channel feedback information of vehicles gathered at the cybertwin, the co-channel interference caused by the spectrum sharing is leveraged to assist the implementation of secure transmissions in the integrated satellite-terrestrial vehicle network. Specifically, the problems of maximizing the secrecy rate of satellite-to-vehicle link and the terrestrial BS-to-vehicle link are formulated, respectively. To solve such two problems, we propose two corresponding beamforming optimization approaches, where semi-definite relaxation (SDR) and semi-definite programming (SDP) are adopted due to the non-convexity. In addition, the tightness of SDR is proved and the complexity of proposed approaches is also analyzed. Finally, extensive numerical simulations are carried out and results show the effectiveness of our proposed approach.

PERFORMANCE OF RAIN- INDUCED ATTENUATION PREDICTION MODELS FOR TERRESTRIAL LINK IN CAMEROON

Weather, notably rain, has a negative impact on radio wave propagation between terrestrial and earthspace links at frequencies above 10 GHz. Therefore raininduced attenuation is a significant propagation impact that must be considered when designing satellite communication systems. Analysis of rain attenuation for earth-space links in three locations in Cameroon at V, Ku and Ka bands is investigated using four rain attenuation models: The ITU-R P.618 model, Svjatogor model, GarciaLopez model and Bryant model at 42.5° elevation angles. The major goal is to figure out which rain attenuation prediction models are best for satellite communication in this area. Five years (2013–2017) daily rainfall data obtained from the Tropical Rain Measuring MissionPrecipitation Radar (TRMM-PR) and Global Precipitation Measurement (GPM) mission's Core Observatory were used for this study. The results showed that the ITUR P.618, Garcia-Lopez, and Svjatogor models performed best in this region. Attenuation ranged from 15 dB to 16 at 42.5° elevation angle for time exceedance of 0.01% at Kuband in all the study locations. For the Ka-band, attenuation varied between 32 dB and 38 dB. Signal availability at Ku-band is possible based on predicted rain attenuation values for 0.01 %-time exceedance. At Ka and V-band, the predicted rain attenuation values for 0.01%- time exceedance have shown that availability of signal is impossible, which infers losses of the signal during such rainfall events across the selected locations in Cameroon

Realistic Prognostic Modeling of Specific Attenuation due to Rain at Microwave Frequency for Tropical Climate Region

Absorption and scattering of propagated microwave radio signals by atmospheric variables, particularly rainfall, remained a major cause of propagation attenuation losses and service quality degradation over terrestrial communication links. The International Telecommunications Union Radio (ITU-R) reports and other related works in the literature provided information on attenuation due to rain and microwave propagation data. Such propagation attenuation information in the tropical region of Nigeria is destitute, especially at lower radio waves transmission frequencies. Therefore, this study addresses this problem by employing 12-year rainfall datasets to conduct realistic prognostic modeling of rain rate intensity levels. A classification of the rainfall data into three subgroups based on the depth of rainfall in the region is presented. Additionally, an in-depth estimation of specific rain attenuation intensities based on the 12-year rainfall data at 3.5 GHz is demonstrated. On average, the three rainfall classes produced rain rates of about 29.27 mm/hr, 73.71 mm/hr, and 105.39 mm/hr. The respective attenuation values are 0.89 dB, 1.71 dB, and 2.13 dB for the vertical polarisation and 1.09 dB, 1.20 dB, and 2.78 dB for the horizontal polarisation at 0.01% time percentage computation. Generally, results indicate that higher rain attenuation of 12% is observed for the horizontal polarisation compared to the vertical polarisation. These results can provide valuable first-hand information for microwave radio frequency planning in making appropriate decisions on attenuation levels due to different rainfall depths, especially for lower frequency arrays.

Uplink Outage Performance of NOMA-Based Hybrid Satellite-Terrestrial Relay Networks Over Generalized Inhomogeneous Fading Channels

In this paper, we investigate the outage performance of an uplink (UL) non-orthogonal multiple access (NOMA)-based hybrid satellite-terrestrial relay network (HSTRN), in which two users communicate with the satellite through a decode-and-forward (DF) relay due to the lack of direct link. To provide a comprehensive yet hitherto unexplored outage analysis framework, we consider a more generalized channel model, i.e., the terrestrial and satellite links, respectively, undergo <inline-formula> <tex-math notation="LaTeX">$\alpha -\mu $ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\kappa -\mu $ </tex-math></inline-formula> shadowed fadings. Under fixed power allocation (FPA) for both multiple access phase and relaying phase, we firstly study three successive interference cancellation (SIC) decoding schemes, of which the first two are refined from existing schemes, while the third one, named as <i>extended SIC (ESIC)</i>, is proposed in this paper to satisfy the quality of service (QoS) decoding criterion, which is shown to offer better performances for both users as compared to the former two SIC schemes. We also propose a novel dynamic power allocation (DPA) scheme for the multiple access phase, termed as <i>enhanced DPA (EDPA)</i>, to overcome both users&#x2019; error floor (EF) issue yet provide better user fairness than the conventional DPA in the literature. We then analyze the exact and asymptotic outage performance for three SIC and the <i>EDPA</i> schemes under the generalized channel setting. It is shown that both the proposed <i>ESIC</i> and <i>EDPA</i> can circumvent the EF issue and moreover, each has its own advantage in terms of the diversity order (DO). Our results also reveal that there exists a trade-off between <i>ESIC</i> and <i>EDPA</i>, since the former requires a premise on users&#x2019; targets rates to overcome the EF and once this premise is satisfied, no DO degradation will occur, while the latter does not entail such a premise but may face potential DO degradation. Finally, we present numerical results to verify the theoretical analysis, manifest the impacts of key parameters on the system performance, and demonstrate the advantages of our proposed network over other benchmarks.

Investigation of the Vertical Profile Radio Refractivity Gradient and Effective Earth Radius Factor (k-factor) in Transmission Link Over Oyo, Oyo State, South Western Nigeria

Surface radio refractive gradient and k-factor are very imperative in observing propagation conditions, designing and planning of microwave communication links in the lower part of the atmospheric boundary layer. The measurement of weather variables (air temperature, atmospheric pressure, relative humidity and wind speed) were conducted in this study at the School of Science, Emmanuel Alayande College of Education, Oyo (7.83°N, 3.95°E), Oyo State, Nigeria. The research was carried out for a period of one year (January to December, 2020) using self-designed cost effective portable weather monitoring systems. The systems were sited from the ground to a height of 200 m on a 220 m Nigeria Television Authority (NTA) UHF channel 37 tower at Oke-Apitipiti in Oyo Town of Oyo State. The calculated daily and monthly averages data are employed to investigate the vertical surface radio refractivity and its refractivity gradient. The highest value of -1.093E+26 N-units/km was recorded in January, while the month of July experienced the least of about -9.305E+19 N-units/km. The months of January–July verified sub-refractive conditions with propagation conditions having varying degree of occurrence. On the other hand, super-refraction and ducting were recorded mostly between August–December from the study. The results also find applicability in radio engineering for refining VHF/UHF terrestrial links based on clear-air considerations which will support operational planning of terrestrial radio networks in Oyo, South Western Nigeria&#x0D; Keywords: Microwave; k-factor; refractivity gradient; sub-refractive; super-refraction

1000 Gbps MDM-WDM FSO link employing DP-QPSK modulation scheme under the effect of fog

In this work, a dual polarization-quadrature phase shift keying (DP-QPSK) modulation scheme has been used for analysing the performance of terrestrial MDM-WDM FSO link at a data rate of 1000 Gbps. The proposed link has been investigated considering linearly polarized (LP) 01 and 02 modes with a channel capacity and spacing of 10 × 100 Gpbs and 10 GHz respectively. The performance of the system has been evaluated in terms of received optical power and signal to noise ratio (SNR) for clear weather, light, medium and heavy fog conditions over a propagation range varying from 1.2 km to 20 km.

Secrecy outage analysis for UAV assisted satellite-terrestrial SWIPT systems with NOMA

This paper studies the physical-layer security for a non-orthogonal multiple access (NOMA) based unmanned aerial vehicle (UAV) assisted hybrid satellite-terrestrial simultaneous wireless information and power transfer system. Specifically, a satellite sends confidential information on a NOMA basis to two terrestrial users through a UAV relay under the wiretapping of an eavesdropper. A power splitting protocol is deployed to coordinate information decoding and energy harvesting. Assuming the satellite link experiences Shadowed-Rician fading and the terrestrial links are subject to Nakagami-m fading, the analytical expressions for the secrecy outage probability and the probability of strictly positive secrecy capacity for two users are derived and the accuracy of the results is verified by Monte-Carlo simulations.

Performance evaluation of metric measures for converting 30-min GPM rain data to 1-min for microwave applications in Tropical region of Nigeria: A multivariate approach

The quest for a one-minute rain rate is high because it is an important input for generating high accuracy of rain-induced attenuation and will in turn earn good use by radio engineers in designing good and high-quality terrestrial and satellite links. This study utilizes eleven (11) years (2008–2018) rain rate data obtained from a satellite-based program, the Global Precipitation Measurement (GPM) over five different locations in the South West, Nigeria, and 2 years (2017 and 2018) gauge measured rain rate data in one of the locations Akure, Nigeria for validation. The GPM platform was an improved satellite-based program over the Tropical Rainfall Measuring Mission (TRMM) for measuring tropical rainfall with spatial and temporal resolution. Hence, a good application of measured GPM rain rate data can be a good tool for estimating rain-induced attenuation if an adequate conversion is made for a one-minute integration regime as recommended by the \\International Telecommunication Union (ITU). The 30 min GPM rain rate data was converted to one-minute integration time based on a multivariate approach. The coefficient of determination of GPM rain rate data closely matches with the gauge and was found to be 0.9194. Analyses were also performed on seasonal bases for rain rate and rain-induced attenuation ranging from frequencies 10 GHz, to 30 GHz, to assess the seasonal trend between the two sources of data. The seasonal analyses were scaled as pre-monsoon, intensive, cessation, and dry months. A seasonal comparison shows that the GPM data presented the highest rain rate and rain attenuation during the intense rainy regime. Attenuations are considerably high at 0.01, 0.005, and 0.001 percentages of time. Overall, a deduction was made that the GPM rain rate measurements offered reliability in the estimation of rain-induced attenuation analyses in the tropical region of Nigeria due to the spatial–temporal coverage when compared with the rain gauge coverage which is sparse and costly to implement. This research has presented a reliable 30 min to one-minute integration time conversion model suitable for tropical locations, as well as information on seasonal rain attenuation statistics which would be utilized for effective satellite communication systems by the radio engineers.

On the ergodic sum rate for multiuser satellite–aerial–terrestrial networks

In this paper, we investigate the ergodic sum rate (ESR) for the downlink of a multi-user satellite–aerial–terrestrial network (SATN) with decode-and-forward (DF) protocol, where a multi-antenna unmanned aerial vehicle (UAV) acts as an aerial relay to assist the signal convey from satellite to multiple terrestrial users, which is also corrupted by co-channel interference. To maximize the ESR of the considered system, a beamforming (BF) scheme based on statistical channel state information is proposed to conduct space division multiple access (SDMA) in the UAV–terrestrial links. Then, by assuming that the satellite–UAV link and the UAV–terrestrial links undergo correlated Shadowed-Rician fading and correlated Rayleigh fading, respectively, we derive the analytical expression of ESR for our considered system with proposed BF scheme. Finally, numerical results are provided to verify the correctness of the theoretical analysis and demonstrate the superiority of our proposed BF scheme.

Hybrid Direction of Arrival Precoding for Multiple Unmanned Aerial Vehicles Aided Non-Orthogonal Multiple Access in 6G Networks

Unmanned aerial vehicles (UAV) have attracted increasing attention in acting as a relay for effectively improving the coverage and data rate of wireless systems, and according to this vision, they will be integrated in the future sixth generation (6G) cellular network. Non-orthogonal multiple access (NOMA) and mmWave band are planned to support ubiquitous connectivity towards a massive number of users in the 6G and Internet of Things (IOT) contexts. Unfortunately, the wireless terrestrial link between the end-users and the base station (BS) can suffer severe blockage conditions. Instead, UAV relaying can establish a line-of-sight (LoS) connection with high probability due to its flying height. The present paper focuses on a multi-UAV network which supports an uplink (UL) NOMA cellular system. In particular, by operating in the mmWave band, hybrid beamforming architecture is adopted. The MUltiple SIgnal Classification (MUSIC) spectral estimation method is considered at the hybrid beamforming to detect the different direction of arrival (DoA) of each UAV. We newly design the sum-rate maximization problem of the UAV-aided NOMA 6G network specifically for the uplink mmWave transmission. Numerical results point out the better behavior obtained by the use of UAV relays and the MUSIC DoA estimation in the Hybrid mmWave beamforming in terms of achievable sum-rate in comparison to UL NOMA connections without the help of a UAV network.

RAIN FADE ANALYSIS AND LINK BUDGET PLANNING FOR 14.8-15.3 GHz TERRESTRIAL MICROWAVE LINKS OPERATING IN PENINSULA MALAYSIA

Most of the reported works on fade duration analyses were mainly based on the ITU-R method. Other related works were based on experimental radio links (less than 1 km path length) rather than actual operational radio links. However, empirical evidences have shown that ITU-R method is not excellently accurate for analyzing the link budgets of terrestrial microwave links operating in tropical and equatorial climates, hence the motivation for this study. The measured rain rate and attenuation on seven, geographically spread, terrestrial microwave links in tropical Malaysia are analysed in this article. The rain attenuation data were collected from 7 DIGI MINI-LINKs operating at Ku-band (14.8 – 15.3 GHz) with 99.95 % availability. The results were used to determine rain fade depth corresponding to a particular rain event on each of the links. The experimental results (attenuation, path reduction and receive signal level) were also compared with the ITU-R predictions. The fades predicted by ITU-R method are comparable to those obtained experimentally; however there is noticeable discrepancy between the experimental and ITU-R path reduction. The rain fade depth increases both with increasing path length and rain rate. More so, the RSLs predicted by the ITU-R method are higher compared to those of experimental values especially at extremely high rain rates, which is due to underestimation of the measured attenuation by the former. Therefore, the fade margins based on the ITU-R predictions come with low accuracy. This study is a useful tool for link budget design and planning of terrestrial radio links operating in Peninsula Malaysia and similar tropical equatorial climates.