- Faculty of Electrical Engineering
Dzordza Vasingtona bb.
81000 Podgorica
Enis Kocan
University of Montenegro, Faculty of Electrical Engineering, Faculty Member
This paper analyzes the performance of non-orthogonal multiple access techniques used in the fifth generation of mobile networks. Examples of downlink NOMA (Non-orthogonal Multiple Access) systems on a channel with Rayleigh's... more
This paper analyzes the performance of non-orthogonal multiple access techniques used in the fifth generation of mobile networks. Examples of downlink NOMA (Non-orthogonal Multiple Access) systems on a channel with Rayleigh's frequency nonselective fading analyzed the probability of error per bit (BER - Bit Error Rate) in different scenarios with three and four users in the case of BPSK (Binary Phase Shift Keying) ) and QPSK (Quadrature Phase Shift Keying) modulations. The results obtained by Monte Carlo simulations show that BER depends on the state of the channel at the transmitter side (CSIT - Channel State Information at the Transmitter), the method of power distribution among users and the applied modulation techniques. BER is higher for users who have poorer CSIT, but decreases with increasing transmission power. A fixed power distribution was applied, which showed that the obtained results were not optimal. Also, in cases of application of BPSK modulation, it has been shown that signal reception is more reliable.
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This paper shows how the information capacities of users in a system based on the non-orthogonal multiple access change depending on the power assigned to users. In the paper is considered the case of downlink communication between a base... more
This paper shows how the information capacities of users in a system based on the non-orthogonal multiple access change depending on the power assigned to users. In the paper is considered the case of downlink communication between a base station and three users located at different distances from the base station. Users have different characteristics of communication channels and their signal components are exposed to Rayleigh fading. The results show that the appropriate selection of the power allocation coefficients can affect the information capacity of each of the users. Selection of the power allocation coefficients is crucial for the proper functioning of the NOMA technique.
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WiFi (Wireless Fidelity) networks are nowadays the most used technology for Internet access and besides this, they represent favorable communication solution for many Internet of things (IoT) application areas. However, the radiofrequency... more
WiFi (Wireless Fidelity) networks are nowadays the most used technology for Internet access and besides this, they represent favorable communication solution for many Internet of things (IoT) application areas. However, the radiofrequency (RF) spectrum used by WiFi networks cannot satisfy increasing capacity demands of upcoming multimedia and IoT services. Thus, using wide available bandwidths in an optical portion of spectrum revived research attention as an interesting solution for future 6G wireless networks. A technology similar to WiFi, but operating in optical spectrum is denoted as LiFi (Light Fidelity). LiFi uses light emitting diode (LED) for data transmission, thus being energy efficient, widely available solution for high-speed data transfer, mostly considered as WiFi complementary technology. In this paper we provide overview of main concepts of LiFi networks, state of the art in standardization activities, their advantages and distinguishing application areas, as well as implementation issues. Moreover, we present main features of terahertz communications, as a competing technology to LiFi towards 6G networks.
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IEEE 801.11 Working Group is developing the sixth generation of wireless local area network (WLAN) standards, denoted as 802.11ax. The main goal of the new standard is to improve 2,4GHz and 5GHz network performance, in scenarios with... more
IEEE 801.11 Working Group is developing the sixth generation of wireless local area network (WLAN) standards, denoted as 802.11ax. The main goal of the new standard is to improve 2,4GHz and 5GHz network performance, in scenarios with multiple overlapping and dense basic service sets (BSSs). In this paper we highlight two novel solutions proposed in the new standard, i.e. implementation of 1024-QAM in modulation and coding scheme (MCS) 11 and BSS color for avoiding interference in overlapping BSSs. For assessment of the level of throughput enhancement attained through implementation of MCS 11, we compare 802.11ax and 802.11ac network performance in indoor communication scenario, assuming multi-user environment. For examining BSS color efficiency, we compare throughput of three overlapping BSSs in an outdoor environment, in scenarios with BSS color enabled and disabled at network nodes. All results are obtained using ns-3 network simulator and they confirm the efficiency of the novel solutions for performance enhancement in IEEE 802.11ax networks, as the achieved throughput increase ranges from 14-18% when using MCS 11, and up to 47% with implementing BSS color, in the assumed scenarios.
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Index modulation (IM) technique is introduced in orthogonal frequency division multiplexing (OFDM) based systems as an extension of spatial modulation (SM) principle, assuming that information is delivered to the receiver not only through... more
Index modulation (IM) technique is introduced in orthogonal frequency division multiplexing (OFDM) based systems as an extension of spatial modulation (SM) principle, assuming that information is delivered to the receiver not only through symbols sent by the transmitter, but also through indices of the selected active subcarriers' set. Index modulated OFDM can be very interesting solution for 5G systems, especially in its range-extended deployment, where relaying is applied. In this paper we analyze bit error rate (BER) performance of dual-hop OFDM decode-and-forward (DF) relay system, implementing both IM and SM (OFDM-IM-SM), for different fading statistics on hops, as well as for various system configurations, in terms of the number of active subcarriers. Based on the simulation obtained results, conclusions are derived on the optimal number of active subcarriers for different signal-to-noise ratio (SNR) values. Moreover, the obtained BER results have shown that the SNR boundary, where OFDM-IM-SM relay system outperforms OFDM relay system is shifted toward lower values, in case of line-of-sight communications.
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This paper outlines an extensive analysis of the case of Montenegro’s maritime surveillance system becoming integrated within the European Common Information Sharing Environment (CISE). Threats to secure maritime borders across Europe are... more
This paper outlines an extensive analysis of the case of Montenegro’s maritime surveillance system becoming integrated within the European Common Information Sharing Environment (CISE). Threats to secure maritime borders across Europe are ever-present and regularly demand coordinated efforts between the member states to tackle and prevent them, e.g. illegal immigration across the Mediterranean. Administration for Maritime Safety and Port Management (AMSPM) in Montenegro is a member of the ANDROMEDA EU project that seeks to facilitate deployments and demonstrations of CISE trials across the European regions, towards their endorsement readiness. AMSPM is now at the forefront of assessing and deploying the CISE components in Montenegro. It thus appropriately evaluates the operational aspects, observes the CISE implementations in some European states, formulates the impact for other national stakeholders, as well as the very prospect of the resulting augmented maritime surveillance in t...
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In the development and testing phases of new WSNs, it is of paramount importance to get insight into the traffic exchanged within the network. For this purpose, the sniffers are an irreplaceable tool. In the case where WSN covers a large... more
In the development and testing phases of new WSNs, it is of paramount importance to get insight into the traffic exchanged within the network. For this purpose, the sniffers are an irreplaceable tool. In the case where WSN covers a large area, single sniffer cannot provide a trace of the complete data traffic, due to the attenuation of the wireless signal. This motivates the implementation of a distributed solution with multiple physical sniffers connected over a network. Overhearing the same data traffic by different physical sniffers is likely in such a scenario, resulting in multiple copies of the same data packet appearing in the merged trace. To overcome this issue, realtime traffic filtering needs to be applied. This paper, motivates and proposes a design of a distributed sniffer that can cover a large deployment. The proposed solution is based on the MQTT protocol and Argus software, which enables the sharing of the saved traffic traces through a cloud.
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IEEE 802.11 standardization body has created and adopted its technical solution for dealing with M2M and IoT requirements, specified under “ah” amendment. 802.11ah represents the first sub-1GHz license-exempt wireless local area network... more
IEEE 802.11 standardization body has created and adopted its technical solution for dealing with M2M and IoT requirements, specified under “ah” amendment. 802.11ah represents the first sub-1GHz license-exempt wireless local area network (WLAN) standard. This flexible and scalable communication solution is applicable on wide range of possible use cases, grouped into the three general scenarios: sensors and smart meters, backhaul aggregation and WLAN range extension and cellular off-loading. In this paper we examine analytically packet error rate (PER) performance of 802.11ah system, for the three defined use case scenarios. We applied system parameters given in adopted standard and appropriate modulation and coding schemes (MCSs), as well as channel fading models, depending on use case scenario. The obtained PER results indicate high reliability of the 802.11ah communication links, even for the long-range communications, especially in the cases with transmit powers of 250mW and 1W.
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The sixth generation of Wi-Fi standards, denoted as IEEE 802.11ax, is gathering research interest as the first Wi-Fi standard to address the Quality of Experience (QoE) in dense environments. Members of the Task Group AX have proposed... more
The sixth generation of Wi-Fi standards, denoted as IEEE 802.11ax, is gathering research interest as the first Wi-Fi standard to address the Quality of Experience (QoE) in dense environments. Members of the Task Group AX have proposed several solutions for improving spectrum efficiency in high density scenarios. In this paper we analyze efficiency of Basic Service Set (BSS) color, one of those solutions proposed for spatial reuse and improvement of area throughput. Using ns-3 network simulator, we model a hotspot scenario consisting of 7 overlapping basic service sets, implementing BSS color to identify the source of detected transmission. Nodes in each BSS use two Carrier Sense Thresholds (CSTs) for sensing the channel, where the higher threshold value is being applied for detection of inter-BSS frames. We show that, by selecting higher threshold for detecting frames from other access points (foreign frames), spectrum efficiency can be improved and area throughput can be increased. However, if the value of this threshold is too high, it can have a counterproductive effect, as it increases interference and probability of error in reception. Therefore, we present the upper limit value of CST, which should not be exceeded in the presented communication scenario, as well as a range of threshold values that enables improvement of area throughput.
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This paper presents exemplar cases of adjusting the operations and taskings of an existing maritime safety administration in the Adriatic towards the emerging technologies for enhanced patrolling in maritime surveillance. This work... more
This paper presents exemplar cases of adjusting the operations and taskings of an existing maritime safety administration in the Adriatic towards the emerging technologies for enhanced patrolling in maritime surveillance. This work derives from ongoing COMPASS2020 project that aims to showcase the capabilities of unmanned systems (aerial, underwater) demonstrated in a novel concept of operation (CONOPS). Results will be presented in: REP(MUS) 2020 – NATO, the largest maritime unmanned systems exercise to be held in Portugal at the end of the project. The Montenegrin Maritime Safety Department reviewed and assessed the deployment of novel assets towards with goal of increased effectiveness (i.e. reduction of costs and responses) of its civilian maritime safety and security missions. This practical approach is presented in two exemplar use-cases: 1) an illicit activity, and, 2) a polluting incident, both with a search and rescue finale. They are presented using the Plan-Do-Check-Act m...
This repository contains the datasets of the 6TiSCH Open Data Action experiment of Fed4FIRE. The datasets cover the execution of three application-level test scenarios, building-automation, home-automation and industrial-monitoring, on... more
This repository contains the datasets of the 6TiSCH Open Data Action experiment of Fed4FIRE. The datasets cover the execution of three application-level test scenarios, building-automation, home-automation and industrial-monitoring, on two testbeds, w-iLab.t in Ghent and OpenTestbed in Paris. The reference firmware image used was OpenWSN. The data format is documented at https://benchmark.6tis.ch/.
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The Common Information Sharing Environment (CISE) is an ongoing cooperative development initiative that incrementally incorporates new participants and countries through integrations of facilities for European maritime surveillance. This... more
The Common Information Sharing Environment (CISE) is an ongoing cooperative development initiative that incrementally incorporates new participants and countries through integrations of facilities for European maritime surveillance. This paper outlines some key processes and technicalities required for becoming a part of the CISE, specifically for the case of a maritime surveillance department in Montenegro - Administration for Maritime Safety and Port Management (AMSPM). The content greatly derives from an ongoing European Union (EU) collaborative project - ANDROMEDA and shows the CISE components such as its data model, services and architecture compositions fitting with existing legacy systems for maritime surveillance. We also show some extracts from the Adriatic-Ionian trial, being conducted in the project, using the enhanced CISE features and involving partners from Italy, Greece and Montenegro. The examinations and general guidelines presented are particularly intended to give...
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We examine possibilities for transmit power reduction both from the relay station (R) and the base station (S − Source) on downlink in dual-hop OFDM decode-and-forward (DF) relay system. Two solutions, known for capacity enhancement in... more
We examine possibilities for transmit power reduction both from the relay station (R) and the base station (S − Source) on downlink in dual-hop OFDM decode-and-forward (DF) relay system. Two solutions, known for capacity enhancement in OFDM based relay systems, are applied for improving energy efficiency, while keeping end-user capacity on the same level. In the first analyzed solution, it is assumed that R station has multiple transmit antennas and employs transmit antenna selection (TAS) on subcarrier basis at R station. The second one assumes implementation of ordered subcarrier mapping (SCM) at R station. Additionally, we analyzed a relay system deploying both of these two solutions, i.e. TAS and SCM. We developed simulation model implementing parameters from LTE-Advanced reference scenario in rural environment. The cases of indoor and outdoor placed user are examined. Based on the comparison of achievable mean data rates per subcarrier in each considered system, we derived perc...
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In this paper, the costs and benefits of the National Maritime Single Window (NMSW) for coastal countries that have limited human resources and infrastructure related to maritime traffic are researched. A general method for conducting a... more
In this paper, the costs and benefits of the National Maritime Single Window (NMSW) for coastal countries that have limited human resources and infrastructure related to maritime traffic are researched. A general method for conducting a cost-benefit analysis of NMSW implementation is proposed. Using this method and the input data for Montenegro, as an example of a small-sized coastal country, the authors assess whether such an investment in NMSW implementation can be beneficial to coastal countries with limited resources.
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In 2010 IEEE 802.11ah working group has started with work on designing their first standard in sub-GHz spectrum, with the goal to bring a WLAN standard with extended range, which, among other things, could provide communication services... more
In 2010 IEEE 802.11ah working group has started with work on designing their first standard in sub-GHz spectrum, with the goal to bring a WLAN standard with extended range, which, among other things, could provide communication services in the area of IoT applications. Enhancements of achievable communication range in IEEE 802.11ah are results of modifications done on physical and MAC layer. In this paper we examine performance of IEEE 802.11ah systems in terms of achievable range and bit error rate (BER) of the modulation and coding scheme (MCS) achieving the longest range. In order to examine fading effect on achievable range, we have modeled and compared scenarios with and without fading, in urban environment, where no techniques for fading mitigation are implemented.
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Very efficient and robust frequency synchronization and channel estimation method based on pilot tone usage, for OFDM systems in the case of slow time varying channels is proposed. The presented method uses preamble consisting of just one... more
Very efficient and robust frequency synchronization and channel estimation method based on pilot tone usage, for OFDM systems in the case of slow time varying channels is proposed. The presented method uses preamble consisting of just one OFDM symbol, for channel and frequency offset estimation and additional two pilot tones embedded in each data symbol, for the neutralization of the
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ABSTRACT In this paper the level of bit error rate (BER) performance enhancement achieved by subcarrier mapping (SCM) at the relay (R) station in dual-hop OFDM non-regenerative Variable Gain (VG) relay system, is examined. Closed form BER... more
ABSTRACT In this paper the level of bit error rate (BER) performance enhancement achieved by subcarrier mapping (SCM) at the relay (R) station in dual-hop OFDM non-regenerative Variable Gain (VG) relay system, is examined. Closed form BER expressions are derived for the assumed M-QAM (M-ary Quadrature Amplitude Modulation) modulated system, in the case of Rayleigh fading channels on both hops, when two SCM schemes denoted as Best-to-Best SCM (BTB SCM) and Best-to-Worst SCM (BTW SCM) are implemented. The obtained results show that, for all the signal-to-noise ratio values of interest, the analyzed relay system with BTB SCM achieves better BER performance, or at least the BER performance equal to the case when BTW SCM scheme is implemented. Having in mind that BTB SCM scheme also maximizes the system capacity, it is shown that it can be considered as the optimal SCM scheme for the OFDM non-regenerative VG relay system.
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Abstract This paper analyzes SER (symbol error rate) performance of OFDM (orthogonal frequency division multiplexing) system with polarization diversity. It is assumed that the system consists of dual polarized transmit and receive... more
Abstract This paper analyzes SER (symbol error rate) performance of OFDM (orthogonal frequency division multiplexing) system with polarization diversity. It is assumed that the system consists of dual polarized transmit and receive antennas. Propagation ...
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Based on a common evaluation 5-step methodology, initial performance assessments of the innovative solutions considered within WP4 are carried out. A dozen of radio components and transmission techniques solutions are developed and... more
Based on a common evaluation 5-step methodology, initial performance assessments of the innovative solutions considered within WP4 are carried out. A dozen of radio components and transmission techniques solutions are developed and evaluated through ratio of the Exposure Index. The proposed intermediate performances assessments show a large range of exposure reduction from non-significant to ninety percent reduction, while keeping QoS constant. Despite a large diversity of solutions, the adopted methodology makes possible the comparison of their effectiveness but also allows to highlight some compatibility or at the opposite some conflicts between these solutions. This last point is a mandatory step to prepare solution prioritization and global exposure reduction assessment.
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We analyzed the bit error rate (BER) and ergodic capacity performance improvement of dual-hop OFDM amplify and forward (AF) relay system with fixed gain (FG) at relay station (R), all attained through ordered subcarrier mapping (SCM) at... more
We analyzed the bit error rate (BER) and ergodic capacity performance improvement of dual-hop OFDM amplify and forward (AF) relay system with fixed gain (FG) at relay station (R), all attained through ordered subcarrier mapping (SCM) at R. In previous works we showed that in the region of small values of average signal-to-noise ratios (SNRs) on hops best-to-best SCM (BTB SCM) scheme should be applied, while in the region of medium and high values of average SNRs on hops, BER performance improvement is achieved by implementing best-to-worst SCM (BTW SCM) scheme. In this paper we analyzed a new solution, where in the assumed relay system with BTB SCM, one or more subcarriers having the lowest SNRs on each hop are omitted. Furthermore, we examined power balance of the system implementing SCM through comparison of BER performance expressed as a function of power transmitted per subcarrier, with BER performance of the ordinary OFDM AF FG relay system, as well as with the performance in c...
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OFDM-IM is modulation technique which is able to outperform classical OFDM modulation in terms of spectral and energy efficiency, by exploiting concept of Index Modulation (IM). However, this improvement can be achieved at the expense of... more
OFDM-IM is modulation technique which is able to outperform classical OFDM modulation in terms of spectral and energy efficiency, by exploiting concept of Index Modulation (IM). However, this improvement can be achieved at the expense of worse bit-error-rate (BER) performance for the low to medium signal-to-noise ratio (SNR) values, while for the high SNRs it outperforms OFDM system in terms of BER. Thus, in this paper, we propose a hybrid system for BER minimization, which assumes implementation of OFDM-IM at high SNR values, and classical OFDM at lower SNR values, all based on the known channel characteristics.
mmWave communications are considered as a promising candidate for small-cell deployment in 5G cellular systems. However, communication at these high frequency bands suffers from great path-loss and link outages due to blocking caused by... more
mmWave communications are considered as a promising candidate for small-cell deployment in 5G cellular systems. However, communication at these high frequency bands suffers from great path-loss and link outages due to blocking caused by different obstacles, including user's body. Thus, in this paper we analyze the efficiency of macrodiversity (MD) implementation for coping with these deteriorating effects. Two MD schemes are considered, based on known channel quality indicators (CQIs). The first one assumes that MS always communicates with base station (BS) with the best CQI, while the second MD scheme is proposed in this paper and it assumes that MS switches to another BS if its CQI is 2 levels above the current one. Using mmWave module in the ns-3 simulator, we model three real-case scenarios for downlink (DL) communications at 28GHz and 73GHz bands, in outdoor environment. The obtained results for data rate clearly show that implementation of the proposed MD schemes leads towards significant performance improvement of mmWave cellular systems.
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Abstract-A frequency synchronization method for the specific OFDM receive diversity system, with implemented frequency domain subcarrier selection combining (SC), is proposed. It has been shown that the assumed diversity system is even... more
Abstract-A frequency synchronization method for the specific OFDM receive diversity system, with implemented frequency domain subcarrier selection combining (SC), is proposed. It has been shown that the assumed diversity system is even more sensitive to ...
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Explosive growth of different type of wireless networks in the last decade has raised an issue of influence of electromagnetic fields (EMFs) originating from radio frequencies (RF) to human health. Thus, more and more researchers working... more
Explosive growth of different type of wireless networks in the last decade has raised an issue of influence of electromagnetic fields (EMFs) originating from radio frequencies (RF) to human health. Thus, more and more researchers working on the solutions for the next generation wireless communication systems now have in mind the necessity of keeping the level of radiated power on the minimum level necessary for achieving the required performances. In this paper we analyze solutions for human exposure reduction in dual-hop OFDM (Orthogonal Frequency Division Multiplexing) based decode-and-forward (DF) relay systems, as this type of relay solution is adopted for LTE-Advanced networks, also denoted as 4G. In our approach we seek for the solutions that keep the certain performance metric, i.e. system capacity in this analysis, on the same level like in baseline OFDM DF relay system, but attain exposure reduction from relay station (R) on downlink (DL). In one of the considered solutions, R station, having more than one antenna for DL communication, implements transmit antenna selection (TAS) on subcarrier basis, jointly with ordered subcarrier mapping (SCM). TAS solution assumes that on each subcarrier position, the transmit antenna having the best subcarrier channel transfer function is chosen. Ordered SCM is a technique where subcarriers from the first hop are mapped to corresponding subcarriers on the second hop in accordance to their instantaneous signal-to noise ratios (SNRs). It is proven to be a mapping scheme that maximizes the achievable capacity in OFDM based DF relay systems, enabling bit error rate (BER) improvement at the same time. Besides this solution, we analyze the level of human exposure reduction in the cases where only SCM technique is implemented at R, as well as where only TAS is implemented. We have developed a simulation model for assessing the level of human exposure to EMF, with included real-case simulation parameters given in LTE-Advanced relay reference scenario. In this way, we have obtained and analyzed data on the level of human exposure reduction attained with the proposed solutions in indoor and outdoor environment, and for the different positions of end-users relative to R station