In this article we deal with the issue of network traffic monitoring in large multi-channel wireless IoT networks. Assuming known link conditions on all radio channels, i.e. connectivity matrix ...defined through Packet Delivery Ratio on all frequencies and all links between nodes, we propose two methods for defining the number and the positions of sniffer devices, with the goal to maximize the capture of network traffic. Method I is based on probabilistic theory and assumes brute-force search over the connectivity matrix for defining the optimal positions of a given number of sniffers, or, for a given percentage of the traffic to be captured as the input parameter, this method determines number of sniffers and their locations. Due to the computational complexity of brute-force search of the connectivity matrix, we complement Method I and propose Method II. Method II is based on graph theory and uses the minimal Packet Delivery Ratio on each link as the input parameter for defining the number and position of sniffers. We input traffic traces from an experimental testbed into the network to examine and compare both methods. Results show that the Method I outperforms Method II in the percentage of captured network traffic, for a given number of deployed sniffers. However, Method II complements Method I in scenarios where there are a large number of sniffers, due to lower computational complexity.
For the ITU-R defined enhanced mobile broadband (eMBB) type of generic services, 5G systems will deploy mmWave communications in indoor environments and open area scenarios in outdoor environment. ...Besides very high path-losses and reduced diffraction propagation mechanism, communications at these frequencies are known to be vulnerable to blockage effects caused by different obstacles, including human body. Thus, in this paper we examine efficiency of macro diversity (MD) solution for coping with these deteriorating effects in mmWave systems. In order to avoid frequent switching among base stations (BSs), which are in the communication range of a mobile station (MS), while keeping the performance on the required level, we analyze the best decision criteria for selection of a proper link, based on known channel quality indicators (CQIs). Using ns-3 module for mmWave communications, we model downlink (DL) communication at 28 GHz in mixed-office scenario, with both self-blockage and dynamic blockage included. Different BS and blocker densities are modeled in three real-case scenarios, in terms of MS mobility. The obtained results have confirmed efficiency of MD schemes for improving performance of mmWave communication systems in indoor environment.
Tens of thousands of wireless industrial monitoring deployments exist today, logging more than 18 billion operating hours. These solutions have been around for over a decade and are based on ...standards such as WirelessHART and ISA100.11a to provide performance guarantees to the applications. The new trend in industry deployments is the convergence of operational and information technologies happening through the Industrial Internet of Things (IIoT) paradigm. The challenge is to bridge the performance of these well-proven industrial standards with the interoperability of IP-based systems. The Internet Engineering Task Force (IETF), the organization behind most of the technical solutions of the Internet, has produced a set of specifications with this requirement in mind. The output of this effort is the 6TiSCH protocol stack based on open standards, such as those that have played a key role in the Internet's ubiquitous adoption. The standardization of 6TiSCH is done. The state-of-the-art research work focus is on important, but niche, optimizations and performance evaluations of the 6TiSCH stack. This paper takes a different approach - it evaluates the performance of the standards-compliant 6TiSCH solution from the end user point of view. It does so on two experimental testbeds, in typical IoT test scenarios based on a well-defined experimentation methodology. We provide a set of Key Performance Indicators (KPIs) useful for the end user to decide whether the 6TiSCH technology is a good fit performance-wise for a particular use case. We demonstrate reliability of a vanilla open-source implementation of 6TiSCH above 99.99%, upstream latency on the order of a second and radio duty cycle well below 1%.
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.
A great number of Internet of Things (IoT) and machine-to-machine (M2M) based applications, which are telecommunication areas with the highest foreseen growth in the future years, require energy ...efficient, long range and low data rate wireless communication links. In order to offer a competitive solution in these areas, IEEE 802.11 standardization group has defined the “ah” amendment, the first sub-1 GHz WLAN standard, with flexible channel bandwidths, starting from 1 MHz, up to 16 MHz, and many other physical and link layer improvements, enabling long-range and energy efficient communications. However, for some regions, like Europe, the maximum transmitted power in dedicated frequency band is limited to only 10 mW, thus disabling the achievement of ranges which would be close to targeted of up to 1 km. In this paper we examine possibilities for range extension through implementation of half-duplex decode-and forward (DF) relay station (RS) in communication between an access point (AP) and an end-station (ST). Assuming a Rician fading channel between AP and RS, and a Rayleigh fading channel on RS–ST link, we analytically derive results on achievable ranges for the most robust modulation and coding schemes (MCSs), both on downlink (DL) and uplink (UL). Analyses are performed for two different standard adopted deployment scenarios on RS–ST link, and variable end-to-end link outage probabilities. Moreover, we have analyzed whether the considered most robust MCSs, known for supporting the longest range, but the lowest data rates, can meet the defined requirement of at least 100 kb/s for the greatest attainable AP–RS–ST distances. We examine data rate enhancements, brought by coding and using of short packets, for both DL and UL. Finally, we present bit error rate results, obtained through simulations, of a dual-hop DF IEEE 802.11ah relay system for the considered MCs. All presented results confirm that IEEE 802.11ah systems through deployment of relay stations, become an interesting solution for M2M and IoT based applications, due to flexibility they offer in many aspects, meeting requirements for wide transmission ranges in such applications.
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 the country. This substantiates the content of this paper as the feasibility of the CISE deployment in Montenegro, supported by a snapshot of the cost-benefit analysis. We aspire to offer novel perspectives and insights that could be a universally useful experience to different CISE implementation initiatives, especially for countries or regions of similar smaller sizes and coastal area.
Ergodic capacity of dual-hop orthogonal frequency division multiplexing (OFDM) based decode-and-forward (DF) relay system may be significantly enhanced if ordered subcarrier mapping (SCM) is ...implemented at relay station (R). We proved earlier that this SCM scheme also brings certain bit error rate (BER) performance improvement to assumed system. However, the level of the achieved BER reduction is very small, with no reduction at all for the high signal-to-noise ratios (SNRs) on both hops. Therefore, in this paper we propose a modification of the SCM scheme where one or more subcarriers with the lowest SNRs from both hops are omitted before ordered SCM is performed at the relay station of an OFDM DF relay system. For the scenario with Rayleigh fading statistics on both hops, and no direct communication between the source of information (S) and destination (D), we derived a closed form BER relation of the assumed uncoded BPSK modulated relay system. The analytically obtained BER results, which are verified through simulations, show that the proposed modified SCM scheme brings significant BER performance improvements for all SNR values on both hops. Additionally, in order to provide analytical tool for the assessment of ergodic capacity enhancement achieved through ordered SCM, we derived ergodic capacity expression of the dual-hop OFDM DF relay system with ordered SCM.
Explosive growth of different type of wireless networks in the last decade has raised an issue of influence of electromagnetic fields originating from radio frequencies 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 Orthogonal Frequency Division Multiplexing (OFDM) based decode-and-forward (DF) relay systems, as this type of relay system 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. It is proven to be a mapping scheme that maximizes the achievable capacity in OFDM based DF relay systems, enabling bit error rate 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.
In this paper we propose a novel solution for performance enhancement of dual-hop orthogonal frequency division multiplexing (OFDM) based decode-and-forward (DF) relay system, which assumes that ...relay station uses more than one antenna for downlink communications and implements transmit antenna selection (TAS) on subcarrier basis jointly with ordered subcarrier mapping (SCM). Ordered SCM is 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 ergodic capacity in OFDM based relay systems, while enabling bit error rate (BER) improvement at the same time. In order to assess the level of BER performance improvement in the system proposed in this paper, we analytically derive closed form BER expression of binary phase shift keying modulated OFDM DF relay system with TAS and SCM, assuming a scenario with Rayleigh fading statistics on both hops. Additionally, for further BER reduction, we analyze the combination of TAS with a modified SCM scheme, in which the subcarriers having the lowest SNRs on both hops are omitted. All derived analytical results are completely verified through simulations, showing that significant BER performance improvements are achieved with the novel proposed OFDM relay system, compared to the systems implementing only SCM, or only TAS, which approves that it can be considered as an interesting solution for the next generation of mobile cellular systems.
A multi-relay assisted orthogonal frequency division multiplexing system with index modulation is proposed in this letter, assuming that amplify-and-forward (AF) relaying protocol is adopted at ...relays. Two commonly used AF protocols are considered: 1) fixed-gain AF and 2) variable-gain AF relaying protocols. To utilize relays in an efficient manner, we also employ two multi-carrier relay selection schemes termed bulk and per-subcarrier relay selection in the proposed system. We analyze the outage performance of the proposed system and derive closed-form expressions of the average outage probabilities (AOPs) for all cases with different AF relaying protocols and multi-carrier relay selection schemes. In addition, we obtain the asymptotic expressions of AOPs in the high signal-to-noise ratio region, by which it is proven that the full diversity gain equaling the number of relays is attainable.
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