Jamjareegulgarn, Punyawi

Preferred name

Alternative Name

Jamjareegulgarn, P.

Main Affiliation

KMITL Prince of Chumphon Campus

punyawi.ja@kmitl.ac.th

Now showing 1 - 10 of 96

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Detection of data symbol in a massive MIMO systems for 5G wireless communication
(2017-10-19)
Duangsuwan, Sarun
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Jamjareegulgarn, Punyawi
The massive MIMO technique has played the most important role in 5G wireless communication. It is anticipated that the new techniques employed in massive MIMO will not only improve peak service data rates significantly, but also enhance capacity, coverage, low-latency, efficiency flexibility, compatibility and convergence, thus meeting the focusing demands imposed by optimal detection. This paper presents the optimal detection of data symbol in massive MIMO for 5G wireless communication. Based on the frequency non-selective fading MIMO channel, we consider three difference detectors for recovering the transmitted data symbols and evaluate their performance for Rayleigh fading and additive white Gaussian noise (AWGN). At the results, we show that the probability of error rate (PER) performance of the detectors are significantly discussed.
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Urban rainfall in the Capitals of Brazil: Variability, trend, and wavelet analysis
(2022-04-01)
Oliveira-Júnior, José Francisco de
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Correia Filho, Washington Luiz Félix
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Monteiro, Lua da Silva
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Shah, Munawar
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Hafeez, Amna
The patterns of urban rainfall in Brazil's capitals are critical, due to population growth and extreme weather. Therefore, the objectives are: i) to identify homogeneous rainfall groups and meteorological systems, ii) to evaluate the trend of the monthly rainfall time series and iii) to apply wavelet analysis to estimate the variance at different frequencies in the rainfall series in the capitals of the Brazil. Monthly rainfall data during 1960–2020 for 27 stations located in the capitals of Brazil were used. The data were flawed, and data imputation (mtsdi package) was applied via Fully Conditional Specification (FCS). Rainfall data were submitted to descriptive, exploratory statistics (boxplot), multivariate analysis (Cluster Analysis - CA) and the Mann-Kendall (MK) test. Seven CA methods (Ward, Single, Complete, Average, McQuity, Median and Centroid) were tested using the cophenetic correlation coefficient (CCC) with a significance level of 5%, the Average method obtained CCC > 0.81 (S). The CA identified three homogeneous regions (G1, G2 and G3) in the capitals of Brazil. The G1 group is formed by the capitals of the Northeast of Brazil (NEB), except for Boa Vista, (North of Brazil - NB). The G2 group is the largest group formed by the capitals of the Midwest (MWB), Southeast (SEB) and South (SB) of Brazil. The G3 group is the smallest group, with the capitals of the NB and some of the NEB. The capitals with the category of significant growth trend were only Porto Alegre and Florianópolis (SB), Vitória (SEB) and Belém (NB). The category of non-significant increase trend prevailed in most capitals of Brazil, with emphasis on the corridor formed between the NB and the Center-South, except for Natal (NEB). The without trend category prevailed in the North, Northeast and Midwest regions of Brazil. Monthly precipitation analyzes for trend detection purposes via Wavelet Analysis showed that ENSO phases are significant in rainfall variability in Brazilian capitals.
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Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia
(2021-09-01)
Abadi, P.
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Otsuka, Y.
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Liu, Hui Xin
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Hozumi, K.
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Martinigrum, D. R.
Previous studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre-reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April and September–October in 2010–2013 to investigate influences of the eastward neutral wind and the EEJ on the PRE’s strength. Our analysis employs data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite to determine the zonal (east-west direction) neutral wind at an altitude of ~250 km (bottomside F region) at longitudes of 90°–130°E in the dusk sector. Three ionosondes, at Chumphon (dip lat.: 3.0°N) in Thailand, at Bac Lieu (dip lat.: 1.7°N) in Vietnam, and at Cebu (dip lat.: 3.0°N) in Philippines, provided the data we have used to derive the PRE strength. Data from two magnetometers — at Phuket (dip lat.: 0.1°S) in Thailand and at Kototabang (dip lat.: 10.3°S) in Indonesia — were used to estimate the EEJ strength. Our study is focused particularly on days with magnetically quiet conditions. We have found that the eastward neutral wind and the EEJ are both closely correlated with the PRE; their cross-correlation coefficients with it are, respectively, 0.42 and 0.47. Their relationship with each other is weaker: the cross-correlation coefficient between the eastward neutral wind and the EEJ is just 0.26. Our findings suggest that both the eastward neutral wind and the EEJ near sunset are involved in the PRE mechanism. Based on the weak relationship between these two parameters, however, they appear to be significantly independent of each other. Thus, the wind and the EEJ are likely to be influencing the PRE magnitude independently, their effects balancing each other.
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Singular spectrum analysis of GPS derived ionospheric TEC variations over Nepal during the low solar activity period
(2020-04-01)
Ansari, Kutubuddin
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Panda, Sampad Kumar
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Jamjareegulgarn, Punyawi
Accurate modeling of ionospheric total electron content (TEC) is an important aspect for mitigating the threats of trans-ionospheric delay error in satellite communication, earth observation, space-based navigation, timing applications as well as space weather forecasting services. In recent years, singular spectrum analysis (SSA) has been proved to be a powerful technique giving a relatively accurate estimate in time-series analysis comparable to the contemporary methods. In the current study, the SSA has been implemented on the GPS-derived TEC during the low solar activity year of 2017 over Nepal region which locates itself almost in the vicinity of low-latitudes being sandwiched between India and Tibet, China. The country foresees an explicit investigation and modeling of ionospheric TEC variations and corresponding delay error to precisely accomplish the space-based trans-ionospheric applications. The semi-annual variability of TEC with higher magnitudes during equinoctial seasons and lower values during solstice seasons is clearly noticed in the diurnal plots which are further substantiated by the trajectory matrix of time-series. The decomposed modes in the principal component analysis (PCA) signifies diurnal (first), semidiurnal (second), semiannual (third), monthly (fourth) with higher orders representing associated noise errors in the signals. Correlation coefficients (CC) between the reconstructed and observed time-series demonstrates the SSA method could be a successful tool for forecasting the TEC series over the region. The results are compared with empirical global ionospheric maps (GIMs) and IRI-Plas 2017 models during different seasons, emphasizing the suitability of SSA technique for relatively better precise TEC forecasting over the region.
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Trailing Equatorial Plasma Bubble Occurrences at a Low-Latitude Location through Multi-GNSS Slant TEC Depletions during the Strong Geomagnetic Storms in the Ascending Phase of the 25th Solar Cycle
(2023-10-01)
Vankadara, Ram Kumar
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Jamjareegulgarn, Punyawi
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Seemala, Gopi Krishna
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Siddiqui, Md Irfanul Haque
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Panda, Sampad Kumar
The equatorial plasma bubbles (EPBs) are depleted plasma density regions in the ionosphere occurring during the post-sunset hours, associated with the signal fading and scintillation signatures in the trans-ionospheric radio signals. Severe scintillations may critically affect the performance of dynamic systems relying on global navigation satellite system (GNSS)-based services. Furthermore, the occurrence of scintillations in the equatorial and low latitudes can be triggered or inhibited during space weather events. In the present study, the possible presence of the EPBs during the geomagnetic storm periods under the 25th solar cycle is investigated using the GNSS-derived total electron content (TEC) depletion characteristics at a low-latitude equatorial ionization anomaly location, i.e., KL University, Guntur (Geographic 16°26′N, 80°37′E and dip 22°32′) in India. The detrended TEC with a specific window size is used to capture the characteristic depletion signatures, indicating the possible presence of the EPBs. Moreover, the TEC depletions, amplitude (S4) and phase scintillation (σ<inf>φ</inf>) indices from multi-constellation GNSS signals are probed to verify the vulnerability of the signals towards the scintillation effects over the region. Observations confirm that all GNSS constellations witness TEC depletions between 15:00 UT and 18:00 UT, which is in good agreement with the recorded scintillation indices. We report characteristic depletion depths (22 to 45 TECU) and depletion times (28 to 48 min) across different constellations confirming the triggering of EPBs during the geomagnetic storm event on 23 April 2023. Unlikely, but the other storm events evidently inhibited TEC depletion, confirming suppressed EPBs. The results suggest that TEC depletions from the traditional geodetic GNSS stations could be used to substantiate the EPB characteristics for developing regional as well as global scintillation mitigation strategies.
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Variations in Ionospheric Total Electron Content and Scintillation at GPS stations in Uzbekistan and China during the Annular Solar Eclipse on June 21, 2020
(2025-05-01)
Eshkuvatov, H. E.
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Jamjareegulgarn, Punyawi
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Ahmedov, B. J.
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Tillayev, Y. A.
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Ruziev, Z. J.
This study presents a novel investigation into the distinct ionospheric variations observed over China and Uzbekistan during the annular solar eclipse on June 21, 2020. For the first time, we demonstrate the influence of this celestial event on Total Electron Content (TEC) measurements obtained from GPS satellites. We analyzed fluctuations in TEC and the Ionospheric Scintillation Index (S4) across six strategically selected sites—three in Uzbekistan (MTAL, KIT3, MADK) and three in China (JFNG, LHAZ, BJFS) located near the eclipse path, with obscuration levels of 52%, 57%, 58%, in Uzbekistan and 92%, 94% and 95% in China. Our study involved continuous monitoring of ionospheric parameters over three days, from June 20 to June 22, 2020. Results indicated a significant TEC depletion ranging from 10% to 30% on the day of the eclipse. The analysis reveals that both TEC levels and the S4 scintillation index experienced notable reductions during the event, attributed to the decreased ionizing radiation. These findings enhance our understanding of ionospheric dynamics in response to solar eclipses and have important implications for satellite communication and navigation systems.
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Drought vulnerability assessment using morphometric features and extreme precipitation indicators to prioritize sub-basins: AI-based Fuzzy Logic approach
(2026-03-01)
Nigam, Utkarsh
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Patel, Vinodkumar M.
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Patel, Dhruvesh P.
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Jodhani, Keval H.
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Gupta, Nitesh
The identification of watersheds and extraction of drainage networks are essential for effective hydrological and geomorphological modelling. This study investigates the influence of morphometric factors and extreme precipitation events on the hydrological responses of the Sabarmati River Basin (SRB), India, to identify the drought-vulnerable sub-basins. Watershed prioritization was carried out using satellite remote sensing, GIS, and secondary data, including topographic sheets and ASTER DEM with a spatial resolution of 90 m. The SRB was divided into nine sub-watersheds, and 28 morphometric parameters were evaluated, comprising 07 linear, 15 areal, and 06 relief parameters. A compound factor (CF) was derived using multi-criteria decision-making techniques such as Weighted Sum Analysis (WSA), Principal Component Analysis (PCA), Analytic Hierarchy Process (AHP), Fuzzy-AHP (FAHP), and TOPSIS. Sub-watersheds were ranked based on CF value, where a lower CF indicated higher priority for runoff management strategies. Additionally, 42 years of precipitation data were analysed using the Standardized Precipitation Index (SPI) at timescales ranging from 3 to 24 months to assess trends in drought and extreme precipitation events. The analysis indicate decline in runoff potential in several sub-basins, however others (e.g., SB2, SB3, SB4, SB5) exhibit positive precipitation trends, making them suitable for runoff enhancement. This integrated methodology offers a comprehensive framework for managing sub-basins, optimizing runoff potential, and supporting sustainable water conservation. The results provide actionable insights for policymakers and planners to better utilize the SRB water resources based on its geomorphological and climatic characteristics.
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Positioning Comparison Using GIM, Klobuchar, and IRI-2016 Models During the Geomagnetic Storm in 2021
(2022-01-01)
Srisamoodkham, Worachai
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Ansari, Kutubuddin
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Jamjareegulgarn, Punyawi
This paper compares the positioning accuracy obtained from the GIM VTEC, the Klobuchar model, and the IRI-2016 model at Chiang Mai and DPT9 stations, Thailand, during an intense geomagnetic storm of 2021 (on May 12, 2021). The results show that the diurnal variation of the Klobuchar modeled VTECs show the same trend as that of the observed GIM VTECs with the same peaks and the maximum deviation of 22.5% at 05:00 UT. Meanwhile, the IRI2016-predicted VTECs show its peak at 07:00 UT and are not available obviously during 13:00–21:00 UT due to the impact of this intense geomagnetic storm. Most of the ionospheric delays obtained from the Klobuchar model underestimate those of the GIM VTEC, whereas they overestimate those of GIM VTEC during after midnight and pre-sunrise period. At both stations, the mean ionospheric range delays of the GIM VTEC are highest during daytime period while those of the IRI-2016 model are largest during nighttime period. The positioning errors at higher latitude (CHMA station) are larger than those at lower latitude (DPT9 station).
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Effect of Weighted PDOP on Performance of Linear Kalman Filter for RTK Drone Data
(2022-01-01)
Ansari, Kutubuddin
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Jamjareegulgarn, Punyawi
The study established a theoretical relation between weighted position dilution of precision (WPDOP) and standard deviation (STD) of positioning error ( $\epsilon /\sigma {R})$ derived by linear Kalman filter (KF). The obtained results exposed a rectangular hyperbolic relationship of WPDOP and STD of error. The RTK Drone data were collected around 50 min of interval (07:37 to 08:28 A.M.) on May 12, 2021, with respect to the base station located at 13.841°N; 100.288°E over Thailand region, and a numerical test has been carried out to demonstrate the proposed algorithm. The simulation results verified the theoretical hyperbolic relationship with the distinct flatness of the curve at the base and drone receiver. This different flatness from the experiments was anticipated because of the position errors for the highly nonlinear dynamics motion of the drone receiver while the base receiver is fixed at one location.
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Individual performance of multi-GNSS signals in the determination of STEC over Thailand with the applicability of Klobuchar model
(2022-02-01)
Seok, Hong Woo
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Ansari, Kutubuddin
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Panachai, Chaiwat
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Jamjareegulgarn, Punyawi
Thailand is situated in the southern low latitude region in the Asian longitude sector having much importance as major portion of southern hemisphere is covered by ocean resulting in a sparse density of ground-based monitoring systems. With the establishment of GNSS monitoring stations across the Thailand and neighboring region, it accentuates the ionospheric variability study in the southern hemisphere in the Asian longitude. Therefore, in the current study, we selected four GNSS station located at different part of the country (i.e., CHMA, DPT9, NKRM, and SRTN) and studied the variations of ionospheric slant total electron content (STEC). Here, the STEC observations are estimated by Klobuchar model (namely, Klobuchar-modeled STEC values) and compared with the Global Ionospheric Map (GIM) STEC values for its validation. As an initial study, the Klobuchar-modeled STEC values obtained from five multi-constellation GNSSs over Thailand region (i.e., GPS, GLONASS, Galileo, BeiDou and QZSS) are computed and compared with the GIM STEC values during the intense geomagnetic storm on May 12, 2021 (DOY 132) and during June 2020 to May 2021 for monthly variations. Moreover, to show the relationships between the proposed Klobuchar-modeled STEC values and the GIM STEC values, the correlation coefficients and the root mean square errors between them are computed. The results showed that among the five multi-constellations of GNSSs, the GIM STEC values frequently overestimate the Klobuchar-modeled STEC values, except the QZSS system with the least differences ranging from −10 TECU to 20 TECU. Also, the correlation coefficient between the proposed Klobuchar-modeled and GIM STEC variations span between 0.87 and 0.89, and their RMSEs range from 10 TECU to 11 TECU, excluding QZSS system with less than 10 TECU. The correlation coefficients of higher than 0.85 can be considered as a good indicator for the applicability of Klobuchar model in practice with multi constellation systems.

Jamjareegulgarn, Punyawi

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