ALEKSANDAR Neskovic - Academia.edu (original) (raw)

Papers by ALEKSANDAR Neskovic

2015 23rd Telecommunications Forum Telfor (TELFOR), 2015

Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže vii ... more Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže vii procedure nadmetanja za medijum. Rezultati poređenja varijanti predloženog protokola sa osnovnim HMCP protokolom po ostvarenom protoku i kašnjenju u mreži dokazale su opravdanost uvođenja podrške QoS u MCMI mreže. Na kraju, na osnovu međusobnog poređenja predloženih varijanti protokola, doneti su zaključci koja varijanta QoS-HMCP protokola daje optimalne rezultate (najveći protok i najmanje kašnjenje), za koje saobraćajne kategorije i pod kojim mrežnim uslovima. Pored navedenog, doprinos disertacije ogleda se i u detaljnom i sistematičnom pregledu postojećih protokola rutiranja, strategija dodela kanala, i metrika rutiranja za višekanalne višeinterfejsne WMN. Ključne reči: Višekanalne višeinterfejsne bežične mesh mreže, Protokoli rutiranja, Kvalitet servisa, Metrike rutiranja, Nivo snage signala na prijemu. Naučna oblast: tehničke nauke, elektrotehnika Uža naučna oblast: telekomunikacije UDK broj: 621.3 Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže viii

2021 29th Telecommunications Forum (TELFOR), 2021

One of the quite frequent activities happening in many operators nowadays is technology sunset (2... more One of the quite frequent activities happening in many operators nowadays is technology sunset (2G/3G), mostly due to lack of capacity in 4G where the need for spectrum is constantly growing, so spectrum re-farming from 2G/3G to 4G is often the only option left. However, this puts a big challenge on speech services which are still mostly handled by 2G/3G. This paper describes methodology used to assess the readiness of the network for securing good VoLTE service as the only speech option when 2G/3G technology sunset happens. It is based on the modeling of existing real LTE network data for VoLTE use case, giving VoLTE readiness status of each sector in the network as well as prioritization per problem severity for the sectors which are identified as problematic. It will also summarize possible resolution options for critical sectors depending on their current configuration and environment.

2018 7th Mediterranean Conference on Embedded Computing (MECO), 2018

GPRS terminals are used as internal or external communication devices, sending tax related inform... more GPRS terminals are used as internal or external communication devices, sending tax related information from fiscal cash registers and fiscal printers to a tax administration server, so cybersecurity is of paramount importance. This paper analyzes cybersecurity of GPRS terminals, which are used in many countries.

2017 25th Telecommunication Forum (TELFOR), 2017

This paper describes the results of frequency-domain indoor radio channel characterization using ... more This paper describes the results of frequency-domain indoor radio channel characterization using vector network analyzer in the 1.7–1.9 GHz frequency band. Channel impulse response estimate was obtained via inverse Fourier transform through repeated measurements of its transfer function. Statistical parameters of radio propagation, namely the channel's power delay profile and cumulative distributions of root mean square delay spread, mean excess delay and coherence bandwidth were evaluated and comparisons with results in literature were drawn.

Multimedia Tools and Applications, 2016

Overlapped fingerprints are often found in latent fingerprints lifted from crime scenes and in li... more Overlapped fingerprints are often found in latent fingerprints lifted from crime scenes and in live-scan fingerprint images when the surface of fingerprint sensors contains residues of fingerprints of previous users. Such overlapped fingerprints usually cannot be processed accurately by contemporary commercial fingerprint matchers, which has led many researchers to propose methods designed to separate the overlapped fingerprints. In this paper, we propose a novel latent overlapped fingerprints separation algorithm based on neural networks. Our algorithm works in a block-based fashion. After producing an initial estimation of the orientation fields present in the overlapped fingerprint image, it uses a neural network to separate the mixed orientation fields, which are then post-processed to correct remaining errors and enhanced using the global orientation field enhancement model. Experimental results show that the proposed algorithm outperforms the state-of-theart algorithm in terms of accuracy on the Tsinghua Overlapped Latent Fingerprint Database (containing real-world overlapped fingerprints obtained by forensic methods), while also showing encouraging results (second only to state-of-the-art) on the Tsinghua Simulated Overlapped Fingerprint Database (containing artificially overlapped fingerprints of a good quality).

Proceedings of the 2012 IEEE International Symposium on Antennas and Propagation, 2012

ABSTRACT This paper presents compensation of all undesired effects (Power Amplifier (PA) nonlinea... more ABSTRACT This paper presents compensation of all undesired effects (Power Amplifier (PA) nonlinearity, transmitter and receiver antenna crosstalk, before-PA nonlinear crosstalk, Multiple Input Multiple Output (MIMO) channel fading and crosstalk) in MIMO Orthogonal Frequency Division Multiplex (OFDM) wireless systems. It has been demonstrated that reduced-complexity Crossover Digital Predistortion (CO-DPD) algorithm on transmitter side and Matrix Inversion algorithm on receiver side can suppress almost all undesired effects introduced by transmitter, channel and receiver in 4×4 MIMO OFDM System that can be used in modern wireless system applications. A significant complexity reduction is achieved due to the fact that Digital Signal Processing (DSP) during CO-DPD process on transmitter side is done with real instead of complex numbers.

AEU - International Journal of Electronics and Communications, 2011

A novel method for short-term fading simulation is presented in this paper. Proposed solution is ... more A novel method for short-term fading simulation is presented in this paper. Proposed solution is based on artificial neural network principles. In order to obtain an adequate training data set, extensive measurements of the received electric field strength were carried out in an indoor environment, in a nonline-of-sight scenario. As quality assessment of the proposed method, performance comparisons were made with existing Rayleigh fading simulation methods. The statistical analysis of the short-term fading sequence obtained by the proposed method has shown better correspondence with measurement results as compared to other analyzed methods.

AEU - International Journal of Electronics and Communications, 2010

Abstract A new microcell prediction model for mobile radio environment is presented in this paper... more Abstract A new microcell prediction model for mobile radio environment is presented in this paper. The popular feedforward artificial neural networks (ANN) are used as an optimizing tool to build the model, making possible to overcome some important disadvantages of known, both deterministic and statistical prediction models. In order to build the model, extensive electric field strength measurements were carried out in the city of Belgrade, for four different test transmitter locations. The analysis of the model has shown that the proposed model is fast, accurate (on the order of the local mean measurements uncertainty), reliable and suitable for computer implementation.

2017 25th Telecommunication Forum (TELFOR), 2017

The passive relay station implemented with two back-to-back antennas presents a possible, simple ... more The passive relay station implemented with two back-to-back antennas presents a possible, simple and cost-effective solution to achieve better radio-coverage quality inside the buildings. This paper presents theoretic analysis of the back-to-back solution for such application, followed by the experimental testing of one practical solution through the extensive measurement of achieved radio-coverage characteristics of an existing PMR network inside several electrical transformer station buildings. The measurement results confirmed, to a large extent, the results of the theoretical analysis, and it is concluded that the given solution, under the certain conditions, can be successfully applied for radio-coverage improvement inside the observed and similar type of buildings.

2017 25th Telecommunication Forum (TELFOR), 2017

The experimental analysis of the electromagnetic radiation originating from WLAN devices was carr... more The experimental analysis of the electromagnetic radiation originating from WLAN devices was carried out on the laboratory topology of the WLAN, by measuring the electric field strength originating from the access point on the one hand and the WLAN client on the other. The results of the measurement show that electromagnetic radiation largely depends on the type of used service, and that the obtained values are significantly below the prescribed reference limits.

Serbian Journal of Electrical Engineering, 2020

In this paper, the impact of the network architecture on signal quality in the fourth generation ... more In this paper, the impact of the network architecture on signal quality in the fourth generation of the public mobile network is analyzed. The analysis was performed using RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), SINR (Signal to Interference plus Noise Ratio) and throughput parameters in indoor environment. The signal quality parameters were collected by measurement using TEMS Investigation and TEMS Pocket software. The measurements were carried out at the School of Electrical Engineering on the ground floor of the Technical Faculty building for the macro and micro cell scenario. It has been found that better signal quality is ensured in micro cells. Quality of the signal is also considered by the various services provided to the users.

Wireless Personal Communications, 2018

Given Public Land Mobile Networks (PLMN) ubiquitous infrastructure and excellent coverage, they c... more Given Public Land Mobile Networks (PLMN) ubiquitous infrastructure and excellent coverage, they can be used for providing location information for various location-based services, especially in indoor environments. This paper investigates indoor positioning solutions which utilize received signal strength measurements obtained by mobile device from PLMN cells belonging to multiple mobile network operators. Two indoor positioning methods, based on Support Vector Machine learning algorithms and space-partitioning principle, are proposed. The first method utilizes Support Vector Regression (SVR) algorithm, whilst the second one introduces space-partitioning principle and the combined use of Support Vector Classification and SVR algorithms. The proposed techniques are thoroughly investigated in a real indoor environment. In addition, several criteria for choosing relevant cells for the positioning purposes have been explored. Positioning with SVR has demonstrated good results, while utilizing space-partitioning principle has further reduced the average positioning error by 27%. Moreover, the proposed solution has outperformed positioning methods based on k Nearest Neighbours and Artificial Neural Networks, when implemented in the same verification test bed.

IET Image Processing, 2018

Annals of Telecommunications, 2018

Individual exposure to electromagnetic field (EMF) originating from a user device when using diff... more Individual exposure to electromagnetic field (EMF) originating from a user device when using different services over WLAN (Wireless Local Area Network), GSM (Global System for Mobile communications), and UMTS (Universal Mobile Telecommunications Service) technologies in different radio conditions is analyzed. The most common types of traffic were chosen (voice, Skype, web browsing, download, upload, video, audio, TV) and tested in areas of good, medium, and bad radio conditions, per wireless technology. Exposure is evaluated using triggered network reports and external measurements performed in a live network, and also using predetermined simulation results. The analysis shows strong dependence of individual EMF exposure on wireless technology, radio conditions, and service used. For all technologies and services, exposure increased with deterioration of radio conditions, except for file upload over UMTS where in bad radio conditions exposure decreased due to impact of higher layer protocols. GSM technology generated highest exposure in all radio conditions and for all services, except file upload service in good radio conditions where WLAN generated higher exposure. File upload service generated highest exposure for all technologies and radio conditions, except for GSM in good radio conditions where video streaming and voice were ahead.

Telfor Journal, 2016

The long-term variability of electric field strength, obtained by band selective measurements for... more The long-term variability of electric field strength, obtained by band selective measurements for GSM 900MHz, DCS 1800MHz and UMTS 2100MHz downlink band in realistic mobile network environment, is considered in this paper. Intensive measurements were carried out for 7 days at each of 7 different locations in an urban area of Belgrade. The measurement results show that each day can be divided into two distinctive periods: one with higher levels of electric field (9h-23h) and one with lower ones (23h-9h). Regarding the days of the week, the results show that the weekend days are slightly different from the working days. Having in mind the need for determination of values averaged over the defined time period, additional uncertainty stemming from telecommunication traffic and transmitter functionalities must be taken into account. Mentioned uncertainty was determined for different time intervals of averaging: 10s, 30s, 1min, 6min, 15min, 30min, 1h, 3h, 5h, 10h, 14h and 24h. Results show that the uncertainty falls within a range of 4.04-12.11% (GSM), 2.71-7.92% (DCS) and 4.69-14.69% (UMTS), for 6 different categories defined with regard to the days of the week and the specific day periods.

International Journal of Wireless & Mobile Networks, 2015

In NLOS propagation conditions power of direct component can be attenuated significantly. Therefo... more In NLOS propagation conditions power of direct component can be attenuated significantly. Therefore detection of direct component is aggravated which can degrades accuracy of Time of Arrival mobile positioning. The goal of this paper is to determine possibilities to improve estimation of direct component time delay by reducing detection threshold. Three different methods for calculating threshold has been tested and compared in terms of positioning error.

2011 19thTelecommunications Forum (TELFOR) Proceedings of Papers, 2011

ABSTRACT Position information in indoor environments can be procured using diverse approaches. Du... more ABSTRACT Position information in indoor environments can be procured using diverse approaches. Due to the ubiquitous presence of WLAN networks, positioning techniques in these environments are the scope of intense research. This paper explores models based on Artificial Neural Networks (ANNs): single ANN positioning models using RSSI, SNR and N values as inputs, and a range of cascade-connected ANN positioning models, utilizing various space-partitioning patterns. The benefits from using cascade-connected ANN structures are shown and discussed. The optimal cascade-connected ANN structure with space partitioning shows 41% decrease in median error and 12% decrease in the average error with respect to the best-performing single ANN model.

IEEE Transactions on Intelligent Transportation Systems, 2013

Procuring location information for intelligent transportation systems is a popular topic among re... more Procuring location information for intelligent transportation systems is a popular topic among researchers. This paper investigates the vehicle location algorithm based on the received signal strength (RSS) from available Global System for Mobile Communications (GSM) networks. The performances of positioning models, which consisted of cascade-connected (C-C) artificial neural network (ANN) multilayer feedforward structures employing the space-partitioning principle, are compared with the single-ANN multilayer feedforward model in terms of accuracy, the number of subspaces, and other positioning relevant parameters. CC ANN structures make use of the fact that a vehicle can be found only in a subspace of the entire environment (roads) to improve the positioning accuracy. The best-performing CC ANN structure achieved an average error of 26 m and a median error of less than 5 m, which is accurate enough for most of the vehicle location services. Using the same RSS database obtained by measurements, it was shown that the proposed model outperforms kNN and extended Kalman filter (EKF)-trained ANN positioning algorithms. Moreover, the presented ANN structures replace not only the positioning algorithms but the overloaded map-matching process as well.

IEEE Communications Surveys & Tutorials, 2000

In this article a review of popular propagation models for wireless communication channels is giv... more In this article a review of popular propagation models for wireless communication channels is given. Macrocell, microcell, and indoor prediction methods are considered separately. Advantages and disadvantages of these models are discussed. Also, some practical improvements of the existing models as well as some new models are given.

IEEE Communications Letters, 2000

A new field strength prediction model for the mobile phone environment is presented. The model is... more A new field strength prediction model for the mobile phone environment is presented. The model is based on the principles of popular feedforward neural networks. Utilizing a new artificial neural network model some important disadvantages of both deterministic and empirical models can be overcome. In order to build the model, extensive field strength measurements were carried out inside two different buildings. The analysis of the model has shown that the proposed model is fast, accurate (on the order of the focal mean measurements uncertainty) and reliable.

2015 23rd Telecommunications Forum Telfor (TELFOR), 2015

Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže vii ... more Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže vii procedure nadmetanja za medijum. Rezultati poređenja varijanti predloženog protokola sa osnovnim HMCP protokolom po ostvarenom protoku i kašnjenju u mreži dokazale su opravdanost uvođenja podrške QoS u MCMI mreže. Na kraju, na osnovu međusobnog poređenja predloženih varijanti protokola, doneti su zaključci koja varijanta QoS-HMCP protokola daje optimalne rezultate (najveći protok i najmanje kašnjenje), za koje saobraćajne kategorije i pod kojim mrežnim uslovima. Pored navedenog, doprinos disertacije ogleda se i u detaljnom i sistematičnom pregledu postojećih protokola rutiranja, strategija dodela kanala, i metrika rutiranja za višekanalne višeinterfejsne WMN. Ključne reči: Višekanalne višeinterfejsne bežične mesh mreže, Protokoli rutiranja, Kvalitet servisa, Metrike rutiranja, Nivo snage signala na prijemu. Naučna oblast: tehničke nauke, elektrotehnika Uža naučna oblast: telekomunikacije UDK broj: 621.3 Optimizacija protokola i metrika rutiranja za višekanalne višeinterfejsne bežične mesh mreže viii

2021 29th Telecommunications Forum (TELFOR), 2021

One of the quite frequent activities happening in many operators nowadays is technology sunset (2... more One of the quite frequent activities happening in many operators nowadays is technology sunset (2G/3G), mostly due to lack of capacity in 4G where the need for spectrum is constantly growing, so spectrum re-farming from 2G/3G to 4G is often the only option left. However, this puts a big challenge on speech services which are still mostly handled by 2G/3G. This paper describes methodology used to assess the readiness of the network for securing good VoLTE service as the only speech option when 2G/3G technology sunset happens. It is based on the modeling of existing real LTE network data for VoLTE use case, giving VoLTE readiness status of each sector in the network as well as prioritization per problem severity for the sectors which are identified as problematic. It will also summarize possible resolution options for critical sectors depending on their current configuration and environment.

2018 7th Mediterranean Conference on Embedded Computing (MECO), 2018

GPRS terminals are used as internal or external communication devices, sending tax related inform... more GPRS terminals are used as internal or external communication devices, sending tax related information from fiscal cash registers and fiscal printers to a tax administration server, so cybersecurity is of paramount importance. This paper analyzes cybersecurity of GPRS terminals, which are used in many countries.

2017 25th Telecommunication Forum (TELFOR), 2017

This paper describes the results of frequency-domain indoor radio channel characterization using ... more This paper describes the results of frequency-domain indoor radio channel characterization using vector network analyzer in the 1.7–1.9 GHz frequency band. Channel impulse response estimate was obtained via inverse Fourier transform through repeated measurements of its transfer function. Statistical parameters of radio propagation, namely the channel's power delay profile and cumulative distributions of root mean square delay spread, mean excess delay and coherence bandwidth were evaluated and comparisons with results in literature were drawn.

Multimedia Tools and Applications, 2016

Overlapped fingerprints are often found in latent fingerprints lifted from crime scenes and in li... more Overlapped fingerprints are often found in latent fingerprints lifted from crime scenes and in live-scan fingerprint images when the surface of fingerprint sensors contains residues of fingerprints of previous users. Such overlapped fingerprints usually cannot be processed accurately by contemporary commercial fingerprint matchers, which has led many researchers to propose methods designed to separate the overlapped fingerprints. In this paper, we propose a novel latent overlapped fingerprints separation algorithm based on neural networks. Our algorithm works in a block-based fashion. After producing an initial estimation of the orientation fields present in the overlapped fingerprint image, it uses a neural network to separate the mixed orientation fields, which are then post-processed to correct remaining errors and enhanced using the global orientation field enhancement model. Experimental results show that the proposed algorithm outperforms the state-of-theart algorithm in terms of accuracy on the Tsinghua Overlapped Latent Fingerprint Database (containing real-world overlapped fingerprints obtained by forensic methods), while also showing encouraging results (second only to state-of-the-art) on the Tsinghua Simulated Overlapped Fingerprint Database (containing artificially overlapped fingerprints of a good quality).

Proceedings of the 2012 IEEE International Symposium on Antennas and Propagation, 2012

ABSTRACT This paper presents compensation of all undesired effects (Power Amplifier (PA) nonlinea... more ABSTRACT This paper presents compensation of all undesired effects (Power Amplifier (PA) nonlinearity, transmitter and receiver antenna crosstalk, before-PA nonlinear crosstalk, Multiple Input Multiple Output (MIMO) channel fading and crosstalk) in MIMO Orthogonal Frequency Division Multiplex (OFDM) wireless systems. It has been demonstrated that reduced-complexity Crossover Digital Predistortion (CO-DPD) algorithm on transmitter side and Matrix Inversion algorithm on receiver side can suppress almost all undesired effects introduced by transmitter, channel and receiver in 4×4 MIMO OFDM System that can be used in modern wireless system applications. A significant complexity reduction is achieved due to the fact that Digital Signal Processing (DSP) during CO-DPD process on transmitter side is done with real instead of complex numbers.

AEU - International Journal of Electronics and Communications, 2011

A novel method for short-term fading simulation is presented in this paper. Proposed solution is ... more A novel method for short-term fading simulation is presented in this paper. Proposed solution is based on artificial neural network principles. In order to obtain an adequate training data set, extensive measurements of the received electric field strength were carried out in an indoor environment, in a nonline-of-sight scenario. As quality assessment of the proposed method, performance comparisons were made with existing Rayleigh fading simulation methods. The statistical analysis of the short-term fading sequence obtained by the proposed method has shown better correspondence with measurement results as compared to other analyzed methods.

AEU - International Journal of Electronics and Communications, 2010

Abstract A new microcell prediction model for mobile radio environment is presented in this paper... more Abstract A new microcell prediction model for mobile radio environment is presented in this paper. The popular feedforward artificial neural networks (ANN) are used as an optimizing tool to build the model, making possible to overcome some important disadvantages of known, both deterministic and statistical prediction models. In order to build the model, extensive electric field strength measurements were carried out in the city of Belgrade, for four different test transmitter locations. The analysis of the model has shown that the proposed model is fast, accurate (on the order of the local mean measurements uncertainty), reliable and suitable for computer implementation.

2017 25th Telecommunication Forum (TELFOR), 2017

The passive relay station implemented with two back-to-back antennas presents a possible, simple ... more The passive relay station implemented with two back-to-back antennas presents a possible, simple and cost-effective solution to achieve better radio-coverage quality inside the buildings. This paper presents theoretic analysis of the back-to-back solution for such application, followed by the experimental testing of one practical solution through the extensive measurement of achieved radio-coverage characteristics of an existing PMR network inside several electrical transformer station buildings. The measurement results confirmed, to a large extent, the results of the theoretical analysis, and it is concluded that the given solution, under the certain conditions, can be successfully applied for radio-coverage improvement inside the observed and similar type of buildings.

2017 25th Telecommunication Forum (TELFOR), 2017

The experimental analysis of the electromagnetic radiation originating from WLAN devices was carr... more The experimental analysis of the electromagnetic radiation originating from WLAN devices was carried out on the laboratory topology of the WLAN, by measuring the electric field strength originating from the access point on the one hand and the WLAN client on the other. The results of the measurement show that electromagnetic radiation largely depends on the type of used service, and that the obtained values are significantly below the prescribed reference limits.

Serbian Journal of Electrical Engineering, 2020

In this paper, the impact of the network architecture on signal quality in the fourth generation ... more In this paper, the impact of the network architecture on signal quality in the fourth generation of the public mobile network is analyzed. The analysis was performed using RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), SINR (Signal to Interference plus Noise Ratio) and throughput parameters in indoor environment. The signal quality parameters were collected by measurement using TEMS Investigation and TEMS Pocket software. The measurements were carried out at the School of Electrical Engineering on the ground floor of the Technical Faculty building for the macro and micro cell scenario. It has been found that better signal quality is ensured in micro cells. Quality of the signal is also considered by the various services provided to the users.

Wireless Personal Communications, 2018

Given Public Land Mobile Networks (PLMN) ubiquitous infrastructure and excellent coverage, they c... more Given Public Land Mobile Networks (PLMN) ubiquitous infrastructure and excellent coverage, they can be used for providing location information for various location-based services, especially in indoor environments. This paper investigates indoor positioning solutions which utilize received signal strength measurements obtained by mobile device from PLMN cells belonging to multiple mobile network operators. Two indoor positioning methods, based on Support Vector Machine learning algorithms and space-partitioning principle, are proposed. The first method utilizes Support Vector Regression (SVR) algorithm, whilst the second one introduces space-partitioning principle and the combined use of Support Vector Classification and SVR algorithms. The proposed techniques are thoroughly investigated in a real indoor environment. In addition, several criteria for choosing relevant cells for the positioning purposes have been explored. Positioning with SVR has demonstrated good results, while utilizing space-partitioning principle has further reduced the average positioning error by 27%. Moreover, the proposed solution has outperformed positioning methods based on k Nearest Neighbours and Artificial Neural Networks, when implemented in the same verification test bed.

IET Image Processing, 2018

Annals of Telecommunications, 2018

Individual exposure to electromagnetic field (EMF) originating from a user device when using diff... more Individual exposure to electromagnetic field (EMF) originating from a user device when using different services over WLAN (Wireless Local Area Network), GSM (Global System for Mobile communications), and UMTS (Universal Mobile Telecommunications Service) technologies in different radio conditions is analyzed. The most common types of traffic were chosen (voice, Skype, web browsing, download, upload, video, audio, TV) and tested in areas of good, medium, and bad radio conditions, per wireless technology. Exposure is evaluated using triggered network reports and external measurements performed in a live network, and also using predetermined simulation results. The analysis shows strong dependence of individual EMF exposure on wireless technology, radio conditions, and service used. For all technologies and services, exposure increased with deterioration of radio conditions, except for file upload over UMTS where in bad radio conditions exposure decreased due to impact of higher layer protocols. GSM technology generated highest exposure in all radio conditions and for all services, except file upload service in good radio conditions where WLAN generated higher exposure. File upload service generated highest exposure for all technologies and radio conditions, except for GSM in good radio conditions where video streaming and voice were ahead.

Telfor Journal, 2016

The long-term variability of electric field strength, obtained by band selective measurements for... more The long-term variability of electric field strength, obtained by band selective measurements for GSM 900MHz, DCS 1800MHz and UMTS 2100MHz downlink band in realistic mobile network environment, is considered in this paper. Intensive measurements were carried out for 7 days at each of 7 different locations in an urban area of Belgrade. The measurement results show that each day can be divided into two distinctive periods: one with higher levels of electric field (9h-23h) and one with lower ones (23h-9h). Regarding the days of the week, the results show that the weekend days are slightly different from the working days. Having in mind the need for determination of values averaged over the defined time period, additional uncertainty stemming from telecommunication traffic and transmitter functionalities must be taken into account. Mentioned uncertainty was determined for different time intervals of averaging: 10s, 30s, 1min, 6min, 15min, 30min, 1h, 3h, 5h, 10h, 14h and 24h. Results show that the uncertainty falls within a range of 4.04-12.11% (GSM), 2.71-7.92% (DCS) and 4.69-14.69% (UMTS), for 6 different categories defined with regard to the days of the week and the specific day periods.

International Journal of Wireless & Mobile Networks, 2015

In NLOS propagation conditions power of direct component can be attenuated significantly. Therefo... more In NLOS propagation conditions power of direct component can be attenuated significantly. Therefore detection of direct component is aggravated which can degrades accuracy of Time of Arrival mobile positioning. The goal of this paper is to determine possibilities to improve estimation of direct component time delay by reducing detection threshold. Three different methods for calculating threshold has been tested and compared in terms of positioning error.

2011 19thTelecommunications Forum (TELFOR) Proceedings of Papers, 2011

ABSTRACT Position information in indoor environments can be procured using diverse approaches. Du... more ABSTRACT Position information in indoor environments can be procured using diverse approaches. Due to the ubiquitous presence of WLAN networks, positioning techniques in these environments are the scope of intense research. This paper explores models based on Artificial Neural Networks (ANNs): single ANN positioning models using RSSI, SNR and N values as inputs, and a range of cascade-connected ANN positioning models, utilizing various space-partitioning patterns. The benefits from using cascade-connected ANN structures are shown and discussed. The optimal cascade-connected ANN structure with space partitioning shows 41% decrease in median error and 12% decrease in the average error with respect to the best-performing single ANN model.

IEEE Transactions on Intelligent Transportation Systems, 2013

Procuring location information for intelligent transportation systems is a popular topic among re... more Procuring location information for intelligent transportation systems is a popular topic among researchers. This paper investigates the vehicle location algorithm based on the received signal strength (RSS) from available Global System for Mobile Communications (GSM) networks. The performances of positioning models, which consisted of cascade-connected (C-C) artificial neural network (ANN) multilayer feedforward structures employing the space-partitioning principle, are compared with the single-ANN multilayer feedforward model in terms of accuracy, the number of subspaces, and other positioning relevant parameters. CC ANN structures make use of the fact that a vehicle can be found only in a subspace of the entire environment (roads) to improve the positioning accuracy. The best-performing CC ANN structure achieved an average error of 26 m and a median error of less than 5 m, which is accurate enough for most of the vehicle location services. Using the same RSS database obtained by measurements, it was shown that the proposed model outperforms kNN and extended Kalman filter (EKF)-trained ANN positioning algorithms. Moreover, the presented ANN structures replace not only the positioning algorithms but the overloaded map-matching process as well.

IEEE Communications Surveys & Tutorials, 2000

In this article a review of popular propagation models for wireless communication channels is giv... more In this article a review of popular propagation models for wireless communication channels is given. Macrocell, microcell, and indoor prediction methods are considered separately. Advantages and disadvantages of these models are discussed. Also, some practical improvements of the existing models as well as some new models are given.

IEEE Communications Letters, 2000

A new field strength prediction model for the mobile phone environment is presented. The model is... more A new field strength prediction model for the mobile phone environment is presented. The model is based on the principles of popular feedforward neural networks. Utilizing a new artificial neural network model some important disadvantages of both deterministic and empirical models can be overcome. In order to build the model, extensive field strength measurements were carried out inside two different buildings. The analysis of the model has shown that the proposed model is fast, accurate (on the order of the focal mean measurements uncertainty) and reliable.