Regional Navigation Satellite System Research Articles

Design of Universal Code Generator for Multi-Constellation Multi-Frequency GNSS Receiver

A multi-constellation, multi-frequency Global Navigation Satellite System (GNSS) receiver is capable of simultaneously receiving signals from multiple satellite constellations across various frequency bands. This allows for increased observations, thereby enhancing navigation accuracy, continuity, effectiveness, and reliability. The spread spectrum code structures used in satellite navigation signals differ among systems. Compatible code generators are employed in multi-constellation, multi-frequency GNSS receivers to support tasks such as signal acquisition and tracking. There are three main types of spread spectrum code structures: Linear Feedback Shift Register (LFSR), Legendre sequences, and Memory codes. The Indian Regional Navigation Satellite System (IRNSS) released the L1-SPS (Standard Positioning Service) signal format in August 2023, which utilizes the Interleaved Z4-linear ranging code (IZ4 code) as its spread spectrum code. Currently, there is no universal code generator design compatible with the IZ4 code. In this paper, a proposed universal code generator is based on the hardware structure of the IRNSS IZ4 code generator. It achieves compatibility with all LFSR-based spread spectrum codes and enables parallel generation of multiple sets of GNSS signal spread spectrum codes, thereby improving hardware utilization efficiency. The proposed structure is implemented and validated using FPGA design, and resource consumption is provided as part of the validation results.

A Simplified Gm − C Filter Technique for Reference Spur Reduction in Phase-Locked Loop

This paper presents a wideband approach for L5 and S-band integer-N phase-locked loop (PLL) targeting Indian Regional Navigation Satellite System (IRNSS) applications. A reference spur reduction technique using a Gm−C filter is proposed. The reference spur is improved by 7 dB when compared with one without any Gm−C filter. The wideband integer-N PLL is designed and fabricated in UMC 65-nm CMOS process. The Gm−C filter block consumes 200 μA current. The wideband voltage-controlled oscillator (VCO) oscillates from 1.6 GHz to 3.2 GHz having a tuning range (TR) of 40%, achieving a best and worst phase noise of ≈−122 dBc/Hz and ≈−116 dBc/Hz at a 1 MHz offset, respectively.

An effective automatic processing engine for improving the multi-GNSS constellation precise orbit prediction

Orbit prediction (OP) recently tends to be a very crucial step for supporting real-time GNSS orbit services due to the dynamic stability of navigation satellite orbits. The OP performance depends on the length of the predicted orbits and the accuracy of precise orbit determination (POD) as basis. Considering this, a new automatic processing engine is established for improving the multiple global navigation satellite systems (multi-GNSS) constellation OP performance. From the architecture-oriented high-performance parallel processing perspective, the multi-node and multi-core computer sources are fully exploited to implement the hourly update of the current multi-GNSS POD. For MEO-type satellites (e.g., Galileo satellites), the accuracy of predicted orbits is improved from 3.8 cm, 6.5 cm, and 12.3 cm to 3.5 cm, 4.3 cm, and 6.3 cm, in the radial, cross, and along directions, respectively, compared to the three-hour POD update. Despite the shortened OP length, the OP performance of regional navigation satellite system (RNSS) satellites is still limited due to their regional observability. The BDS-IGSO and QZSS-IGSO satellitesexhibit radial directional orbital errors of up to 36.9 cm and 28.9 cm, respectively. Therefore, an orbit fitting (OF) processing method with orbit reconstruction is implemented into the processing engine. By utilizing this method, the radial orbital errors for BDS-IGSO and QZSS-IGSO satellites can be reduced to 7.0 cm and 10.4 cm, respectively. The mean real-time positioning errors are thus reduced from 28.3 to 18.4 cm and from 24.4 to 18.2 cm in the horizontal and vertical components, respectively.

Data Dissemination Among Vehicles To Aid In Rendering Quick Emergency Services

Abstract Road traffic in metropolitan cities is increasing at enormous rates resulting in congestion. Vehicles rendering emergency services like ambulances, fire engines, law enforcement vehicles, etc., act as lifelines and should be looked into with the highest priorities on the road. Such emergency vehicles (EmVs / EVs) are seen stuck many times in traffic, especially during peak hours of the day. The vehicles that block the EmVs on the road are unaware of the arrival of the same. Hence this work proposes a system that uses a central server that receives the location of the EmV and shares it with the civilian vehicles around. This is achieved through pinpointed accuracy systems like the Indian Regional Navigation Satellite System (IRNSS), Global Positioning System (GPS), and Global System for Mobile Communication (GSM), etc., The objective here is to help the EmVs reach their target location earlier thus saving lives.

Enhancing Navigation Accuracy in a Geostationary Orbit by Utilizing a Regional Navigation Satellite System

Enhancing Navigation Accuracy in a Geostationary Orbit by Utilizing a Regional Navigation Satellite System

The IRNSS/NavIC designing characteristics and development in antenna application: An overview

<p class="abstract">Today is a generation of the satellite navigation system and every country needs its own positioning and secured services. GPS invention has given birth to a new era in technology. India in terms of population is highly dense and should have its own navigation system. High-level research is still going on for Navigation with Indian Constellation (NavIC) the Indian Regional Navigation Satellite System (IRNSS) to be developed for the frequency band L-band (1176.45MHz) and S-band (2492.08 MHz). In this paper, we summarize the attributes characterizing the NavIC antenna which includes patch size, polarization, Fractal attributes, etc. Similarly, the paper gives technical inputs to develop a compact and efficient NavIC antenna system for future L-band and S-band.</p>

Multi-Band Antenna Design by Reshaping Surface Currents of Higher Order Mode Using CMA Method

A multi-band antenna design by surface current reshaping of higher-order modes is presented. This method utilizes characteristic mode analysis to modify the conventional circular patch antenna in accordance with the surface current distribution of higher-order modes at the L5, S, and L1 bands using CMA. The antenna is evaluated up to four modes inducing fundamental mode. The S and L1 bands are obtained by exciting reshaped higher-order modes, while the L5 lower band is obtained by exciting the fundamental mode using full-wave analysis with 50 Ω coaxial feed. The measurement results are very similar to simulated antenna results. The measured operating frequencies of the proposed antenna are 1177.00 MHz (L5-band), 1575.00 (L1-band) MHz, and 2497.50 (S-band) MHz with associated impedance bandwidth (S11 ≤ −10 dB) are 25.30 MHz (1164.40–1189.70 MHz), 65.30 MHz (1535.50–1600.80 MHz), and 48.60 MHz (2464.10–2512.70 MHz) having desired gain with hemispherical radiation characteristics. These bands are used in Global Positioning Services (GPS) and in Indian Regional Navigation Satellite System (IRNSS) applications.

Performance evaluation of BDS-3 new B1C/B2a and legacy B1I/B3I signals: Observational quality, POD and PPP

In addition to the BeiDou regional navigation satellite system (BDS-2) backward compatible B1I and B3I signals, the BeiDou global navigation satellite system (BDS-3) also broadcast the B1C and B2a signals for compatibility with other Global Navigation Satellite System (GNSS), and providing satellite-based augmentation service for the International Civil Aviation Organization. Considering that the majority of the existing researches on the BDS-3 precise orbit determination (POD) and precise point positioning (PPP) are based on the B1I/B3I signals, the special attention that systematically comparing the data quality, POD accuracy and PPP performance through B1I/B3I and B1C/B2a signals is aroused in this paper. Signal characteristics of different receivers and antennas for the aforesaid four various signals were analyzed in terms of the carrier-to-noise density ratio (C/N0), pseudorange multipath and observation noise. The B1C signal exhibits the minimum C/N0 values, and the B3I and B2a signals have the smaller pseudorange multipath errors. The smallest pseudorange noise can be observed form the B2a signal, while the root mean squares (RMSs) for carrier phase noise show tiny differences among the four signals. The BDS-3 POD results indicate that the orbit overlapping arc error in three-dimensional (3D) direction is 0.069 and 0.076 m for the B1C/B2a and B1I/B3I, and the standard deviation of the satellite laser ranging validation is 0.041 m for both the two schemes. The clock offset products were evaluated with respect to the precise clock products from Deutsches GeoForschungsZentrum (GFZ), and the standard deviations (STDs) are 0.166 and 0.176 ns for the B1C/B2a and B1I/B3I. Finally, there is no apparent difference in the RMSs for B1C/B2a and B1I/B3I static PPP, while the convergence time that shortened by 31.4 % can be achieved for B1C/B2a. For kinematic PPP, the 3D RMS is 0.043 m and the convergence time is 31.1 min for the B1C/B2a, which is reduced by 14.0 % and 35.2 %, respectively, compared to B1I/B3I.

Preliminary performance analysis of BeiDou-2/GPS navigation systems over the low latitude region

Abstract On a regional or worldwide scale, satellite-based navigation systems can offer three-dimensional Position, Velocity, and Timing (PVT) services to an indefinite number of users. BeiDou-2 is China’s regional navigation satellite system that encompasses the Asia-Pacific region. BeiDou-2’s space section comprises GEO, MEO, and IGSO satellites, making it unique among the navigation systems. This research focuses on key aspects, including satellite visibility and signal strength, as a function of the elevation angle across the low latitude region (Indian region). In addition, the results were compared with those obtained using the GPS. The data is acquired from a GNSS receiver located at the Hyderabad station (latitude:17°24′28″, longitude:78°31′04″). The results show that BeiDou-2 satellites have better visibility than GPS satellites at all elevation angles. However, visibility is low at high elevations; therefore, multiple systems are required to obtain user information. As the elevation angle increases, the carrier-to-noise density ratio (C/No) also increases. Additionally, the standard deviation (STD) was calculated and compared to that of the GPS. Despite the average signal strength of GPS satellites remaining high throughout the elevation range, the STD of BeiDou-2 satellites was found to be low. These results indicate that further work is needed to improve the interoperability of multiple navigation systems and to provide more accurate location information to Indian users.

An Extended Range Divider Technique for Multi-Band PLL

This paper presents a multiplexer-based extended range multi-modulus divider (ER-MMD) technique for multi-band phase locked loop (PLL). The architecture maintains a modular structure by using conventional 2/3 divider cells and a multiplexer without adding any extra logic circuitry. The area and power overhead is minimal. The 2/3 divider cells are designed using true single phase clock (TSPC) logic for ER-MMD to operate in the sub-10 GHz range. A division range of 2 to 511 is achieved using this logic. The ER-MMD operates at a maximum frequency of 6 GHz with a worst-case current of 625 μA when powered with a 1 V supply. A dual voltage controlled oscillator (VCO), L5/S band PLL for Indian Regional Navigation Satellite System (IRNSS) application is designed, which incorporates an ER-MMD based on the proposed approach as a proof of concept. This technique achieves the best power efficiency of 12 GHz/mW, among the state-of-the-art ER-MMD designs.

Multi‐Wavelength (L and S Band) Study of Ionospheric Irregularities From an Anomaly Crest Location

AbstractThis paper reports observation of moderate to intense scintillations, at S band of Indian Regional Navigation Satellite System (IRNSS). During current solar cycle 25, these occurrences are probably being reported for the first time, from a low‐latitude station Calcutta (22.58°N, 88.38°E geographic; magnetic dip 34.54°), located near the northern crest of Equatorial Ionization Anomaly. Efforts have been made to analyze irregularity dynamics at IRNSS S band, along with a comparative study at GNSS L1 to characterize occurrence and evolution of multiscale irregularity structures. Power spectral analysis technique has been applied on recorded C/NO, during scintillation patches, to measure east‐west zonal drift velocity. Efforts are also made to study intensity of signal perturbation at L5 frequency of IRNSS, compared to S band, when observed simultaneously, during period of ionospheric scintillation. Concurrent irregularity dynamics at L1, L5, and S band, particularly from a low‐latitude station, has not been extensively reported earlier. Data is recorded during vernal equinox (February–April 2022) of current solar cycle. Results of this study show occurrence of simultaneous night‐time scintillation at L1, L5, and S band. East‐west zonal drift velocity of irregularity, obtained from S band observations are found to decrease with the progress of time during 20–23 LT having a maximum value of 125 m/s. At GNSS L1, hourly average value of the velocity, is observed to maximize during 20–21 LT. Simultaneous observation of scintillation effects at L5 and S band of IRNSS led to loss‐of‐lock at L5, while no such occurrence was noted at S band.

Comparative analysis of regression algorithms for the prediction of NavIC differential corrections

Abstract Indian Regional Navigation Satellite System (IRNSS) or Navigation with Indian Constellation (NavIC) provides positioning, navigation and timing information services to various users in Indian region. Standalone NavIC may not meet the position accuracies for certain application such as civil aviation. Differential NavIC is used for improving the position accuracy of rover receiver, which make use of differential corrections (transmitted from reference station). However, if the satellite signals are temporarily lost due to abruptly changing atmosphere, satellite health issues or if the satellite signals are attenuated due to city infrastructures in urban areas, tree canopies, the accuracy of NavIC will be degraded. This article compares regression tree and bagging tree based differential corrections prediction algorithm with the actual differential corrections, by considering the NavIC satellite signal strength (C/No) and elevation angle (El), to improve the NavIC positioning accuracy. The improvement in the position accuracy is obtained by utilizing predicted differential corrections. The position accuracy of rover using actual differential corrections (2DRMS – 3.09 m), regression tree predicted differential corrections (2DRMS – 5.96 m) and bagged tree predicted differential corrections (2DRMS – 3.06 m) are compared. Here, the rover accuracy using actual differential corrections and bagged tree predicted differential corrections are approximately equal. So, the position accuracy using bagged tree predicted differential corrections are accurate when compared to regression tree predicted differential corrections.

Signal-in-Space Range Error of the Global BeiDou Navigation Satellite System and Comparison with GPS, GLONASS, Galileo, and QZSS

Based on the standard of precise multisystem orbit and clock offset, the evaluation methods of satellite orbit, satellite clock offset and the signal-in-space range error (SISRE) from broadcast ephemeris were given in this study. The SISRE was used as a key performance index to compare the global BeiDou navigation satellite system (BDS-3) with the regional navigation satellite system (BDS-2), Global Positioning System (GPS), Galileo, Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS), and Quasi-Zenith Satellite System (QZSS). Through the combination of domestic tracking stations and inter satellite links, the orbit determination accuracy of BDS-3 has been significantly improved. The radial (R), tangential (T) and normal (N) direction orbit accuracies of BDS-3 medium Earth orbit (MEO) satellites were 0.08, 0.37, and 0.34 m, respectively, which were considerably better than those of other satellite navigation systems. The R-, T-, and N-direction orbit accuracies of BDS-3 inclined geosynchronous orbit (IGSO) satellites were 0.17, 0.59, and 0.56 m, respectively, which were better than those of QZSS IGSO satellites. The R-, T-, and N-direction orbit accuracies of BDS-3 geostationary earth orbit (GEO) satellites were 0.27, 3.42, and 1.29 m, respectively, revealing considerable accuracy advantages in the R and N directions compared with QZSS GEO, although performance in the T direction was inferior. For the clock offset, the BDS-3 MEO satellites had an accuracy of 1.83 ns, which was noticeably superior, similar, slightly inferior, and superior to those of BDS-2, GPS, Galileo, and GLONASS. The clock offset accuracies of BDS-3 IGSO and GEO satellites were 3.13 and 3.17 ns, respectively, which were slightly better than those of QZSS IGSO and GEO satellites but did not have an obvious advantage over BDS-2. The primary reason could be that the launch time of the two types of BDS-3 satellites was close to the analysis period, and therefore, the clocks may be still in the aging process. Considering only orbit error, the average SISRE (orb) of BDS-3 MEO, Galileo, GPS, and GLONASS was 0.10, 0.28, 0.57, and 1.03 m, respectively. The SISRE (orb) of BDS-3 IGSO was 0.19 m, which was marginally greater than that of BDS-3 MEO but smaller than those of the other systems and considerably smaller than that (0.90 m) of QZSS IGSO. The SISRE (orb) of BDS-3 GEO was 0.60 m, which was comparable to that of GPS (0.59 m) and considerably smaller than that of QZSS GEO (0.91 m) satellites. Considering both orbit and clock offset error, the SISRE of BDS-3 MEO satellites was 0.52 m, which was slightly greater than that of Galileo (0.40 m), marginally smaller than that of GPS (0.59 m), and considerably smaller than that of GLONASS (2.33 m). The BDS-3 IGSO satellites had a SISRE of 0.90 m, which was greater than those of GPS and Galileo but comparable to that of QZSS IGSO (0.92 m). The average SISRE of BDS-3 GEO satellites was 1.15 m, which was greater than those of GPS and Galileo and slightly greater than that of QZSS0.95 m GEO satellites, but smaller than that of GLONASS.

РЕГІОНАЛЬНА НАВІГАЦІЙНА СУПУТНИКОВА СИСТЕМА ЯК ДЖЕРЕЛО PNT ПІД ЧАС НАВМИСНИХ ТРИВАЛИХ ЗАГРОЗ СИГНАЛАМ GNSS

The article is devoted to consideration of the possibility, in the conditions of growing threats to the stable functioning of GPS and other GNSS systems due to long-term deliberate interference, to use as an alternative, more protected source of PNT (Position, Navigation, Time) signals, a local satellite navigation system, which will be capable to function, providing coverage of all or a significant part of the territory of Ukraine. The possibilities and limitations of using already existing satellites in geosynchronous orbits (GEO, IGSO) as relayers of PNT information in the event that such NAVSOP signals will be created and transmitted through them by specialized ground stations. The peculiarities of adaptation and improvement of such technical solutions for the conditions of Ukraine are considered along with the possibility of using VSAT stations adapted to such a system, which are part of satellite communication systems using satellites in geostationary orbits with the use of interference-resistant coding and DSSS (Direct Sequence Spread Spectrum) signals that will significantly reduce the possibility of their detection and make it more difficult to counter their reception during long-term threats to GNSS signals.In addition, theimplementation of authentication algorithms in such systems will make it possible to ensure their protection against detection and alteration of data transmission, and to increase the accuracy of PNT determination and expand the scope of application in the future, the regional navigation satellite system (RNSS) can be transformed into a hybrid one by supplementing it with additional sources of PNT and NAVSOP.

Improving the Position Accuracy of Rover Receiver using Differential Positioning in Indian Regional Navigation Satellite System

Navigation with Indian Constellation (NavIC) is the Indian Regional Navigation Satellite System (IRNSS) developed by Indian Space Research Organization (ISRO) to provide the position and navigation services for Indian region. NavIC or IRNSS is individual satellite constellation which has seven satellites covering the Indian subcontinent. Accuracy of NavIC standalone is insufficient in certain applications such as civil aviation. To improve the position accuracy performance of NavIC system, differential positioning technique is utilized. In this paper, differential positioning is carried out, considering two IGS (IRNSS-GPS-SBAS) receivers (one as reference station and the other as rover), which are capable of receiving IRNSS signals from 7 satellites, GPS signals from 12 satellites, SBAS signals from 2 satellites. Here, NavIC constellation alone is considered for the analysis. The differential positioning is carried out using the pseudorange measurements on L5 (1176.45 MHz), S1 (2492.028 MHz) and dual (L5 and S1 both) and accuracies are compared in terms of the statistical parameters Circular Error Probability (CEP), Distance Root Mean Square (DRMS), 2DRMS (twice the DRMS). The improvement in the horizontal accuracy (2DRMS) of the rover using pseudorange measurements on L5 is observed to be 78.81%, on S1 it is 69.14 % and using dual frequency (L5 and S1 both) it is 80.73% when compared to NavIC standalone.

Reconfigurable polarization and pattern microstrip antenna for IRNSS band applications

In this article, polarization and pattern reconfigurable antenna is designed for 2.492 GHz Indian Regional Navigational Satellite System (IRNSS) band. The proposed antenna consists of a square radiating element fed with quad coaxial probes for polarization reconfigurability. It is surrounded by switch loaded octagonal parasitic ring for pattern beamwidth reconfigurability. RF switch loaded Electronically feeding network is used to fed the proposed antenna. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) is realized by exciting feed ports in the antenna with 90° phase difference. At the same time switch loaded parasitic ring provides the pattern beamwidth reconfigurability for designed circularly polarized antenna. To verify the proposed design, a prototype is fabricated and tested experimentally. The measured axial ratio is well-below 3 dB in polarization mode. The measured 3 dB beam-width of the elevation gain patterns for the horizontal field component (Gϕ) varies between 107.40°∼113.51° and 74°∼77.55° in pattern reconfigurable modes. The maximum gain of 6.46 dBi is achieved in both polarization and pattern reconfigurable mode. The proposed antenna is intended for the IRNSS navigation receiver system and designed to minimize the effect of interference incident on the antenna by narrowing the pattern beamwidth near the horizon.

Orbit determination of BeiDou navigation satellite system maneuvered satellites based on instantaneous velocity pulses parameters

The BeiDou navigation satellite system (BDS) comprises geostationary earth orbit (GEO) satellites as well as inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites. Owing to their special orbital characteristics, GEO satellites require frequent orbital maneuvers to ensure that they operate in a specific orbital window. The availability of the entire system is affected during the maneuver period because service cannot be provided before the ephemeris is restored. In this study, based on the conventional dynamic orbit determination method for navigation satellites, multiple sets of instantaneous velocity pulses parameters which belong to one of pseudo-stochastic parameters were used to simulate the orbital maneuver process in the orbital maneuver arc and establish the observed and predicted orbits of the maneuvered and non-maneuvered satellites of BeiDou regional navigation satellite system (BDS-2) and BeiDou global navigation satellite system (BDS-3). Finally, the single point positioning (SPP) technology was used to verify the accuracy of the observed and predicted orbits. The orbit determination accuracy of maneuvered satellites can be greatly improved by using the orbit determination method proposed in this paper. The overlapping orbit determination accuracy of maneuvered GEO satellites of BDS-2 and BDS-3 can improve 2–3 orders of magnitude. Among them, the radial orbit determination accuracy of each maneuvered satellite is basically better than 1 m. simultaneously, the combined orbit determination of the maneuvered and non-maneuvered satellites does not have a great impact on the orbit determination accuracy of the non-maneuvered satellites. Compared with the multi GNSS products (indicated by GBM) from the German Research Centre for Geosciences (GFZ), the impact of adding the maneuvered satellites on the orbit determination accuracy of BDS-2 satellites is less than 9 %. Furthermore, the orbital recovery time and the service availability period are significantly improved. When the node of the predicted orbit is traversed approximately 3 h after the maneuver, the accuracy of the predicted orbit of the maneuvered satellite can reach that of the observed orbit. The SPP results for the BDS reached a normal level when the node of the predicted orbit was 2 h after the maneuver.

Evolution of Maritime GNSS and RNSS Performance Standards

The primary means for electronic position fixing in use in contemporary maritime transport are shipborne GPS (Global Positioning System) receivers or DGPS (Differential GPS) receivers. More advanced GNSS (Global Navigation Satellite System) or RNSS (Regional Navigation Satellite Systems) receivers are able to process combined signals from American GPS, Russian GLONASS, Chinese Beidou (BDS), European Galileo, Indian IRNSS, and Japan QZSS. Satellite-based augmentation systems (SBAS) are still not commonly used in the maritime domain, especially onboard vessels certified under international SOLAS convention. The issues and weaknesses of existing International Maritime Organization recommendations, guidelines, requirements, performance standards, and policies on GNSS shipborne sensors are discussed and presented in the paper. Many problems that have already been dealt with in other means of transportation are still to be solved in the maritime domain. The integrity monitoring is addressed as the main issue, and recommendations based on solutions implemented in aviation and the latest research are proposed. Finally, the strengths, weaknesses, opportunities, and threats awaiting maritime GNSS standardization process are outlined.

An efficient approach for anti-jamming in IRNSS receivers using improved PSO based parametric wavelet packet thresholding

The Indian Regional Navigation Satellite System provides accurate positioning service to the users within and around India, extending up to 1500 km. However, when a receiver encounters a Continuous Wave Interference, its positioning accuracy degrades, or sometimes it even fails to work. Wavelet Packet Transform (WPT) is the most widely used technique for anti-jamming in Global Navigation Satellite System receivers. But the conventional method suffers from threshold drifting and employs inflexible thresholding functions. So, to address these issues, an efficient approach using Improved Particle Swarm Optimization based Parametric Wavelet Packet Thresholding (IPSO-PWPT) is proposed. Firstly, a new parameter adaptive thresholding function is constructed. Then, a new form of inertia weight is presented to enhance the performance of PSO. Later, IPSO is used to optimize the key parameters of WPT. Finally, the implementation of the IPSO-PWPT anti-jamming algorithm is discussed. The performance of the proposed technique is evaluated for various performance metrics in four jamming environments. The evaluation results manifest the proposed method’s efficacy compared to the conventional WPT in terms of anti-jamming capability. Also, the results show the ability of the new thresholding function to process various signals effectively. Furthermore, the findings reveal that the improved PSO outperforms the variants of PSO.

Indian Regional Navigation Satellite System (IRNSS) Channel Model for Suburban Area

In this work, a robust channel model for the newly developed Indian Regional Navigation Satellite System (IRNSS) has been proposed considering a dynamic scenario due to receiver movement. The channel model takes into account various channel impairments such as random shadow fading with multipath fluctuations as well. Capturing the dynamic range variation, a two-state channel model is proposed here. The versatile Nakagami-lognormal (NL) composite distribution function is used for both the channel states, and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -means clustering algorithm has been used for state separation. An extensive measurement campaign has been conducted at the L5-band of the IRNSS system to obtain real-time fading data, on which the non-linear curve fitting method has been used to extract pertaining channel model parameters. The accuracy of the proposed channel model is measured quantitatively using quantitative metrics such as mean square error (mse) and Kullback–Leibler divergence (KLD). The illustrated results showing the close match between the modeled and empirically obtained data validate the fact that the proposed channel model can be used to capture the combined effect of random shadowing and multipath in the received IRNSS signal.