Showing papers by "Preben Mogensen published in 2017"
TL;DR: The results show that path loss exponent decreases as the UAV moves up, approximating freespace propagation for horizontal ranges up to tens of kilometers at UAV heights around 100 m.
Abstract: The main goal of this letter is to obtain models for path loss exponents and shadowing for the radio channel between airborne unmanned aerial vehicles (UAVs) and cellular networks In this pursuit, field measurements were conducted in live LTE networks at the 800 MHz frequency band, using a commercial UAV Our results show that path loss exponent decreases as the UAV moves up, approximating freespace propagation for horizontal ranges up to tens of kilometers at UAV heights around 100 m Our findings support the need of height-dependent parameters for describing the propagation channel for UAVs at different heights
289 citations
04 Jun 2017
TL;DR: The coverage and capacity of SigFox, LoRa, GPRS, and NB-IoT is compared using a real site deployment covering 8000 km2 in Northern Denmark and the conclusion is that the 95 %-tile uplink failure rate for outdoor users is below 5 % for all technologies.
Abstract: In this paper the coverage and capacity of SigFox, LoRa, GPRS, and NB-IoT is compared using a real site deployment covering 8000 km2 in Northern Denmark. Using the existing Telenor cellular site grid it is shown that the four technologies have more than 99 % outdoor coverage, while GPRS is challenged for indoor coverage. Furthermore, the study analyzes the capacity of the four technologies assuming a traffic growth from 1 to 10 IoT device per user. The conclusion is that the 95 %-tile uplink failure rate for outdoor users is below 5 % for all technologies. For indoor users only NB-IoT provides uplink and downlink connectivity with less than 5 % failure rate, while SigFox is able to provide an unacknowledged uplink data service with about 12 % failure rate. Both GPRS and LoRa struggle to provide sufficient indoor coverage and capacity.
192 citations
04 Jun 2017
TL;DR: The results show that Narrowband-IoT, having the best Maximum Coupling Loss performance of 164 dB, also provides the best coverage, despite the fact that LoRa and SigFox deployments with omnidirectional antennas are found to provide 3 dB lower link loss on average.
Abstract: In this simulation work the coverage of GPRS, Narrowband-IoT, LoRa, and SigFox is compared in a realistic scenario, covering 7800 km2 and using Telenor's commercial 2G, 3G, and 4G deployment. The target is to evaluate which of the four technologies provides the best coverage for Internet of Things devices, which may be located deep indoor. The results show that Narrowband-IoT, having the best Maximum Coupling Loss performance of 164 dB, also provides the best coverage. This is despite the fact that LoRa and SigFox deployments with omnidirectional antennas are found to provide 3 dB lower link loss on average. In the deployment 11 % of the geographical area contains devices, located both in rural and urban areas. The NB-IoT has an outage below 1 % for locations experiencing 20 dB indoor penetration loss in addition to the outdoor path loss. SigFox performs similarly, while LoRa cannot provide coverage for 2 % of those locations. For the challenging deep indoor case, where 30 dB additional penetration loss is expected, NB-IoT has 8 % outage while SigFox and LoRa is unable to cover 13 % and 20 % of the locations. The four technologies may not be deployed at all existing site locations and therefore the work also includes a study of the coverage as a function of the minimum Inter-Site Distance, where sites closer than 2, 4, and 6 km are filtered out. The results show that SigFox and NB-IoT have outage probabilities below 5 % even though sites closer than 4 km are removed from the simulations.
138 citations
19 Mar 2017
TL;DR: The measurements show that there is a 22-33 % probability of interfering signals above -105 dBm within the mandatory LoRa and SigFox 868.0-868.6 MHz band in a shopping area and a business park in downtown Aalborg, which thus limits the potential coverage and capacity of LoRaand SigFox.
Abstract: In this measurement study the signal activity and power levels are measured in the European Industrial, Scientific, and Medical band 863-870 MHz in the city of Aalborg, Denmark. The target is to determine if there is any interference, which may impact deployment of Internet of Things devices. The focus is on the Low Power Wide Area technologies LoRa and SigFox. The measurements show that there is a 22-33 % probability of interfering signals above -105 dBm within the mandatory LoRa and SigFox 868.0-868.6 MHz band in a shopping area and a business park in downtown Aalborg, which thus limits the potential coverage and capacity of LoRa and SigFox. However, the probability of interference is less than 3 % in the three other measurement locations in Aalborg. Finally, a hospital and an industrial area are shown to experience high activity in the RFID subband 865-868 MHz, while the wireless audio band 863-865 MHz has less activity.
138 citations
TL;DR: The measurements reveal that LTE can provide coverage for 99 percent of the outdoor and road users, but the LTE-M or NarrowBand-IoT upgrades are required in combination with other measures to allow for additional penetration losses, such as those experienced in underground parking lots.
Abstract: Long Term Evolution, the fourth generation of mobile communication technology, has been commercially deployed for about five years. Even though it is continuously updated through new releases, and with LTE Advanced Pro Release 13 being the latest one, the development of the fifth generation has been initiated. In this article, we measure how current LTE network implementations perform in comparison with the initial LTE requirements. The target is to identify certain key performance indicators that have suboptimal implementations and therefore lend themselves to careful consideration when designing and standardizing next generation wireless technology. Specifically, we analyze user and control plane latency, handover execution time, and coverage, which are critical parameters for connected mobility use cases such as road vehicle safety and efficiency. We study the latency, handover execution time, and coverage of four operational LTE networks based on 19,000 km of drive tests covering a mixture of rural, suburban, and urban environments. The measurements have been collected using commercial radio network scanners and measurement smartphones. Even though LTE has low air interface delays, the measurements reveal that core network delays compromise the overall round-trip time design requirement. LTE's breakbefore- make handover implementation causes a data interruption at each handover of 40 ms at the median level. While this is in compliance with the LTE requirements, and lower values are certainly possible, it is also clear that break-before-make will not be sufficient for connected mobility use cases such as road vehicle safety. Furthermore, the measurements reveal that LTE can provide coverage for 99 percent of the outdoor and road users, but the LTE-M or NarrowBand-IoT upgrades, as of LTE Release 13, are required in combination with other measures to allow for additional penetration losses, such as those experienced in underground parking lots. Based on the observed discrepancies between measured and standardized LTE performance, in terms of latency, handover execution time, and coverage, we conclude the article with a discussion of techniques that need careful consideration for connected mobility in fifth generation mobile communication technology.
107 citations
01 May 2017
TL;DR: System-level simulations of the downlink performance show that the URLLC requirements, i.e. latencies below 1 ms and 99.999% reliability, are achievable at low load scenarios, whereas some performance degradation is experienced at higher loads due to the increased queuing delay and inter-cell interference.
Abstract: Ultra-reliable low-latency communications (URLLC) entail the transmission of sporadic and small packets, with low latency and very high reliability. Among many potential areas of optimization for URLLC, the problems of large delays during HARQ retransmissions, and inaccurate link adaptation as a consequence of the rapidly-varying interference conditions are studied. The former is addressed by reducing the TTI length and HARQ round-trip time, as compared to what is used in LTE; whereas including low-pass filtered interference information in the CQI report is also proved to have great potential. Extensive system-level simulations of the downlink performance show that the URLLC requirements, i.e. latencies below 1 ms and 99.999% reliability, are achievable at low load scenarios, whereas some performance degradation (1 – 3 ms latency) is experienced at higher loads due to the increased queuing delay and inter-cell interference.
91 citations
04 Dec 2017
TL;DR: Findings show that GF procedures are capable of providing significant lower latency than GB at the reliability level of 1-e-5, even at considerable network loads, as a function of the load using extensive and detailed system level simulations.
Abstract: In the context of 5'th Generation (5G) New Radio (NR), new transmission procedures are currently studied for supporting the challenging requirements of Ultra-Reliable Low-Latency Communication (URLLC) use cases. In particular, grant free (GF) transmissions have the potential of reducing the latency with respect to traditional grant-based (GB) approaches as adopted in Long Term Evolution (LTE) radio standard. However, in case a shared channel is assigned to multiple users for GF transmissions, the occurrence of collisions may jeopardize the GF potential. In this paper, we perform a system analysis in a large urban macro network of several transmission procedures for uplink GF transmission presented in recent literature. Specifically, we study K-Repetitions and Proactive schemes along with the conventional HARQ scheme referred to as Reactive. We evaluated their performance against the baseline GB transmission as a function of the load using extensive and detailed system level simulations. Our findings show that GF procedures are capable of providing significant lower latency than GB at the reliability level of 1-e-5, even at considerable network loads. In particular, the GF Reactive scheme is shown to achieve the latency target while supporting at least 400 packets per second per cell.
80 citations
19 Mar 2017
TL;DR: The study concludes that without interference, both LoRaWAN and Sig fox provides very good indoor coverage of more than 99 % and Sigfox can provide uplink and downlink failure rates of less than 1 % for the 95 percentile of the devices for all cells without external interference.
Abstract: In this paper we analyze and discuss the coverage and capacity of Sigfox and LoRaWAN in a large scale urban environments covering 150 km$^2$ in Northern Denmark. First, the study measures and analyzes interference in the European 868 MHz license free industrial, scientific, and medical band, creating a model for the interference. The measured interference in downtown Aalborg has an occurrence rate of 22 % and a generalized extreme value distributed power level. Next, the study compares the coverage of the two Internet of Things network solutions using the existing Telenor cellular site grid both with and without interference from the measured external sources. The study concludes that without interference, both LoRaWAN and Sigfox provides very good indoor coverage of more than 99 %. Furthermore, Sigfox and LoRaWAN can provide uplink and downlink failure rates of less than 1 % for the 95 percentile of the devices for all cells without external interference. Adding the external interference results in an outdoor coverage of 90- 95 % and indoor coverage of 50-80 %. Finally, the uplink and downlink 95 percentile failure rate increases significantly to 50 % for LoRaWAN and exceeds 60 % for Sigfox.
75 citations
27 Sep 2017
TL;DR: This paper uses empirical measurements in live rural LTE networks to assess the impact of uplink and downlink radio interference on the UAV radio connectivity performance, and provides a baseline analysis on the potential of interference mitigation schemes, needed to provide a reliable radio connectivity to the Uavs.
Abstract: The use of Unmanned Aerial Vehicles (UAV) for civilian and commercial services has experienced a significant increase in the past couple of years. Emerging UAV enabled services, however, require extended beyond-visual-line-of-sight geographical range. One key regulatory requirement for these services is that the radio communication link must reliably cover a wide(er) area, when compared to the visual-line-of-sight range radio links currently used. Standardized cellular systems such as Long Term Evolution UMTS (LTE), are an obvious candidate to provide the radio communication link to UAVs. In this paper, we use empirical measurements in live rural LTE networks to assess the impact of uplink and downlink radio interference on the UAV radio connectivity performance. Further, we provide a baseline analysis on the potential of interference mitigation schemes, needed to provide a reliable radio connectivity to the UAVs.
61 citations
27 Sep 2017
TL;DR: Investigating the ability of Long- Term Evolution (LTE) network to provide coverage for Unmanned Aerial Vehicles (UAVs) in a rural area, in particular for the Command and Control (C2) downlink indicates that interference is the dominant factor limiting the cellular coverage for UAVs in the downlink.
Abstract: In this paper we investigate the ability of Long- Term Evolution (LTE) network to provide coverage for Unmanned Aerial Vehicles (UAVs) in a rural area, in particular for the Command and Control (C2) downlink. The study takes into consideration the dependency of the large-scale path loss on the height of the UAV, which is derived from actual measurements, and a real-world cellular network layout and configuration. The results indicate that interference is the dominant factor limiting the cellular coverage for UAVs in the downlink: outage level increases from 4.2% at 1.5m height to 51.7% at 120m under full load condition. Lower network loads or larger inter-site distances reduces the interference and thus improves the coverage significantly: outage at 120m is reduced to only 1.9% under network load of 25% for example. Similar effects are expected to be achievable by static or dynamic interference coordination schemes. In addition, ideal Interference Cancellation (IC) scheme with ability to remove completely the dominant interferer shows less effective for UAVs than for users on the ground. On the other hand, macro network diversity has very good potential for drones, as not only it improves the coverage, but also the reliability of the C2 link.
49 citations
19 Mar 2017
TL;DR: It is demonstrated through a simple analytical model that, for right grouping sizes and initial transmission error rates, the target error probability e.g. 1e-5 can be achieved and it is shown that the suggested scheme can provide improved resource efficiency compared to a single conservative transmission which also avoids re- scheduling.
Abstract: The fifth generation (5G) cellular network demands new solutions to meet, in an efficient way, the stringent targets for ultra-reliable and low latency communication (URLLC), such as 1-1e-5 reliability within 1 ms. In a wireless system, the control signaling of the scheduling process is also a source of errors and delays. Semi-persistent scheduling (SPS) is an option to reduce the signaling, leading to lower latency and improved transmission reliability. However, conventional SPS still applies grant signaling to schedule the retransmission. In this work it is proposed an alternative scheme in which a group of users shares a pre-scheduled resource for retransmission. The benefit is that it provides a retransmission opportunity without needing a scheduling control information. Besides that, if the pre-scheduled resource can not be reallocated, the sharing mechanism avoids excessive capacity loss. It is demonstrated through a simple analytical model that, for right grouping sizes and initial transmission error rates, the target error probability e.g. 1e-5 can be achieved. It is also shown that the suggested scheme can provide improved resource efficiency compared to a single conservative transmission which also avoids re- scheduling.
01 Jun 2017
TL;DR: The radio channel between cellular network and Unmanned Aerial Vehichles (UAVs) is analyzed by means of field measurements performed in a rural environment in Denmark and suggests that there is a height-related degradation on signal-to-interference levels.
Abstract: This paper analyzes the radio channel between cellular network and Unmanned Aerial Vehichles (UAVs). The assessment is done by means of field measurements performed in a rural environment in Denmark. The tests were conducted in an operating LTE network (800 MHz), using a commercial cell phone placed inside the frame of a winged UAV. Trials were conducted with UAV flying at 5 different heights measured above ground level (20, 40, 60, 80 and 100m) and a pathloss regression line was obtained from the results. Thereafter, an analysis of downlink (DL) interference is performed for the reported measurements, which suggests that there is a height-related degradation on signal-to-interference levels. Three possible sources for this effect are also presented and discussed in this paper: expanded radio horizon at higher levels, line-of-sight (LOS) clearing and decreased obstruction of the first Fresnel zone. The importance of a better quantification of these factors are stressed as future work plans are described.
TL;DR: In this article, an empirical multifrequency outdoor-to-indoor path loss model is presented based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5, and 5.2 GHz), up to centimeter (cm)-wave frequencies (10, 18, and 28 GHz).
Abstract: This letter presents an empirical multifrequency outdoor-to-indoor path loss model. The model is based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5, and 5.2 GHz), up to centimeter (cm)-wave frequencies (10, 18, and 28 GHz). The model has applicability similar to the typical 3GPP and ITU-R outdoor-to-indoor simplified models, including the multifrequency formulation recently included in the 3GPP TR 38.900. This letter highlights some of the details behind these simplified models and provides additional modeling for internal multiwall attenuation and associated shadow fading.
TL;DR: Irrespective of the eavesdropper capabilities and channel strengths, the ergodic secrecy rate with full-duplex communication is found to grow linearly with the log of the direct channel signal-to-noise-ratio (SNR) as opposed to the flattened out secrecy rates with conventional half-du Plex communication.
Abstract: Full-duplex communication enables simultaneous transmission from both ends of a communication link, thereby promising significant performance gains. Generally, it has been shown that the throughput and delay gains of full-duplex communication are somewhat limited in realistic network settings, leading researchers to study other possible applications that can accord higher gains. The potential of full-duplex communication in improving the physical-layer security of a communication link is investigated in this contribution. We specifically present a thorough analysis of the achievable ergodic secrecy rate and the secrecy degrees of freedom with full-duplex communication in the presence of a half-duplex eavesdropper node, with both single-user decoding and multi-user decoding capabilities. For the latter case, an eavesdropper with successive interference cancellation and joint decoding capabilities is assumed. Irrespective of the eavesdropper capabilities and channel strengths, the ergodic secrecy rate with full-duplex communication is found to grow linearly with the log of the direct channel signal-to-noise-ratio (SNR) as opposed to the flattened out secrecy rate with conventional half-duplex communication. Consequently, the secrecy degrees of freedom with full-duplex is shown to be two as opposed to that of zero in half-duplex mode.
01 Jun 2017
TL;DR: The findings explicitly quantify how the gains from full duplex communication depend on the traffic profile and the inter-cell interference coupling, and make it an attractive potential technology component for the fifth generation dense small cell cellular system.
Abstract: Full duplex communication promises system performance improvement over conventional half duplex communication by allowing simultaneous transmission and reception. However, such concurrent communication results in strong self interference and an increase in the overall network interference, and can only be exploited when traffic is available in both directions. The potential throughput gains of full duplex communication over conventional half duplex transmission in a small cell network with asymmetric traffic conditions is investigated in this contribution. The throughput performance gains are analysed using tools from stochastic geometry, and further confirmed through extensive system level simulations. Our findings explicitly quantify how the gains from full duplex communication depend on the traffic profile and the inter-cell interference coupling. The demonstrated throughput gains and delay reduction make full duplex communication an attractive potential technology component for the fifth generation dense small cell cellular system.
01 Dec 2017
TL;DR: This paper compares three different classification algorithms, which use standard LTE measurements from the UE as input, for detecting the presence of airborne users in the network and shows how waiting for the final decision can even improve this accuracy to values close to 100%.
Abstract: The overall cellular network performance can be optimized for both ground and aerial users, if different treatment is given for the two user classes. Airborne UAVs experience different radio conditions that terrestrial users due to clearance in the radio path, which leads to strong desired signal reception, but at the same time increases the interference. Based on this, one can for instance use different interference coordination techniques for aerial users as for terrestrial user and/or use specific mobility settings for each class. This paper compares three different classification algorithms, which use standard LTE measurements from the UE as input, for detecting the presence of airborne users in the network. The algorithms are evaluated based on measurements done with mobile phones attached under a flying drone and on a car. Results are discussed showing the advantages and drawbacks for each option regarding different use cases, and the compromise between specificity and sensibility. For the collected data results show reliability close to 99% in most cases and also discuss how waiting for the final decision can even improve this accuracy to values close to 100%.
TL;DR: Performance results for the proposed 5G WA TDD solution show clear benefits over current LTE, for example, reduced latency and more scalable control overhead to better support users with different QoS requirements.
Abstract: A flexible multi-service 5G wide area (WA) solution for time division duplex (TDD) operation is outlined in this article. In particular, the associated frame design is in focus. Given the fundamental tradeoffs between capacity, coverage, latency, and reliability, a flexible solution that allows optimization on a per-link basis is proposed. The solution encompasses the possibility to schedule users with different transmission time intervals to best match their service requirements and radio conditions. Due to the large downlink/uplink transmission power imbalance for each link, asymmetric link operation is proposed, where users operate with different minimum transmission times for the two link directions. This is achieved by using a highly flexible asynchronous hybrid automatic repeat request (HARQ) scheme, as well as a novel solution with in-resource control channel signaling for the scheduling grants. Performance results for the proposed 5G WA TDD solution show clear benefits over current LTE, for example, reduced latency and more scalable control overhead to better support users with different QoS requirements.
TL;DR: Simulation results illustrate that a combination of the centralized cell association and scheduling scheme and interference cancellation at the receiver can provide fifth percentile data rate gains of up to 80% without a detrimental effect on the median user rates, under the applied assumptions and simulation settings.
Abstract: Dense network deployments comprising small cells pose a series of important challenges when it comes to achieving an efficient resource use and curbing intercell interference in the downlink. This paper examines different techniques to treat these problems in a dynamic way, from the network and the receiver sides. As a network coordination scheme, we apply a centralized joint cell association and scheduling mechanism based on dynamic cell switching by which users are not always served by the strongest perceived cell. The method simultaneously results in more balanced loads and increased performance. Interference management at the receiver is achieved through the use of a network-assisted interference cancellation and suppression (NAICS) receiver. In order to further boost the fifth percentile user data rates, the transmission rank at the interferers is selectively reduced by a centralized rank coordination functionality. These mechanisms are evaluated in an LTE-Advanced dense small cell scenario with dynamic traffic. Simulation results illustrate that a combination of the centralized cell association and scheduling scheme and interference cancellation at the receiver can provide fifth percentile data rate gains of up to 80% without a detrimental effect on the median user rates, under the applied assumptions and simulation settings. The gains reach 110% when rank coordination is applied.
TL;DR: 3GPP (Third Generation Partnership Project), the standardization body responsible for standardizing cellular systems, has specified both Narrowband IoT (NB-IoT) and enhanced Machine-Type Communications (eMTC) in LTE release 13, which both have approximately 20 dB better link budget than LTE, and a modem complexity reduced to about 10% of LTE.
Abstract: Internet of Things (IoT) is expected to dramatically increase the number of connected devices. Multiple forecasts estimate that the number of IoT devices to go beyond 100 billion. The only question is when exactly this will take place. However, there is consensus that it will happen. Over the last approximately three decades, Internet has brought a significant impact on our society. And during last decade, the Internet usage has been dramatically boosted by the availability of powerful smartphones and fast connectivity using Wi-Fi and cellular systems. IoT is expected to become the next big leap of the Internet, where almost anything can be connected. For upcoming 5G systems, the requirements aim to support 1000,000 devices per square kilometers. M2M communications is seen as the nerve system for the Internet of Things (IoT). In the past, M2M communications was typically materialized using wired communication in order to achieve high reliability. Additionally the power consumption of the devices was so high that they required external power supply. With the evolution of wireless communication technologies and further evolution of sensor and actuator technologies, the power consumption and cost of wireless machine-type communications have been reduced significantly; and it is expected that this trend continues during forthcoming years. Applications for M2M communications can be divided into two main categories of massive and mission-critical M2M communications depending on their requirements. With massive M2M communications, we mean that the services typically span a very large numbers of devices that are usually equipped with sensors or actuators. Obviously, the amount of data generated by these devices and sensors is normally very small, and having very low latency is not required. In mission-critical M2M communications, on the other hand, very high reliability and availability as well as very low latency are required. Examples for these systems are traffic safety or control, control of critical infrastructure and wireless connectivity for industrial processes. These systems require different type of communications what it is known as Ultra-Reliable and Low-Latency Communications (URLLC). Wireless has several obvious advantages over wired: ease and reduced cost of installation, higher flexibility, and the support of mobility, to mention a few. M2M communications is often divided into local area and wide area technologies. Local area technologies are providing access from a few meters and up to hundreds of meters, whereas wide area technologies provide a link budget allowing connectivity distances up to tens of kilometers. The GSM system has been the most deployed wide area communication system used for M2M communications. However, many operators have recently announced to decommission GSM systems. This calls for new cellular wide-area M2M connectivity solutions, which can be either standalone or fully embedded into already deployed 4G/ LTE networks by means of software upgrades. 3GPP (Third Generation Partnership Project), the standardization body responsible for standardizing cellular systems, has specified both Narrowband IoT (NB-IoT) and enhanced Machine-Type Communications (eMTC) in LTE release 13, which both have approximately 20 dB better link budget than LTE, and a modem complexity reduced to about 10% of LTE. They are also considered as low power technologies. The approximately 20 dB improved link & Sassan Iraji sassan.iraji@aalto.fi
TL;DR: An interference aware inter-cell rank coordination framework for the future fifth generation wireless system is proposed and a game-theoretic interference pricing measure is introduced as aninterference management mechanism to balance the spatial multiplexing versus interference resilience tradeoff.
Abstract: Multiple transmit and receive antennas can be used to increase the number of independent streams between a transmitter–receiver pair, and/or to improve the interference resilience with the help of linear minimum mean squared error (MMSE) receivers. Typically, rank adaptation algorithms aim at balancing the tradeoff between increasing the spatial multiplexing gain through independent streams, and improving the interference resilience property. An interference aware inter-cell rank coordination framework for the future fifth generation wireless system is proposed in this paper. The proposal utilizes results from random matrix theory to estimate the mean signal-to-interference-plus-noise ratio at the MMSE receiver. In addition, a game-theoretic interference pricing measure is introduced as an inter-cell interference management mechanism to balance the spatial multiplexing versus interference resilience tradeoff. Centralized and distributed implementations of the proposed inter-cell rank coordination framework are presented, followed by exhaustive Monte Carlo simulation results demonstrating its performance. The obtained results indicate that the performance of the proposed method is up to 56% better than conventional non interference-aware schemes; and within 6% of the optimum performance obtained using a brute-force exhaustive search algorithm though it incurs much lower computational complexity.
01 Oct 2017
TL;DR: Compared to the 3GPP assumption, both eMTC and NB-IoT can support up to 5dB and 3dB higher uplink coverage, respectively, which shows the potential of these LTE IoT technologies in realistic network deployment conditions.
Abstract: This paper provides an updated analysis of link-budget and coverage performance for LTE IoT technologies: enhancements for machine type communications (eMTC) and narrowband Internet of Things (NB-IoT). Previous studies have used the 3GPP evaluations assumptions and have demonstrated the coverage capabilities of these technologies when they are independently deployed. Some operators are, however, likely to deploy dual-mode networks — eMTC and NB-IoT — with the intent of supporting different applications in the two systems. With all conditions being equal for the two systems in such a scenario, comparison of the eMTC and NB-IoT technologies then requires that all assumptions are aligned. This paper extends the previous studies with the assumptions aligned for eMTC and NB-IoT systems to provide a fair coverage performance comparison. The study shows that compared to the 3GPP assumption, under the aligned assumptions, both eMTC and NB-IoT can support up to 5dB and 3dB higher uplink coverage, respectively. We further show these link budget improvements yield significantly reduced LTE IoT coverage outage in two simulated scenarios based on real network deployments: a wide area rural case and an urban deep indoor case. The results further demonstrate the potential of these LTE IoT technologies in realistic network deployment conditions.
12 Oct 2017
TL;DR: An extensive measurement campaign performed at two large iron ore mining centers in Brazil at the 2.6 GHz band indicates that conventional wisdom is wrong, and radio-frequency propagation in surface mines can be far more elaborate than plain free-space line-of-sight conditions.
Abstract: In this paper we present the results of an extensive measurement campaign performed at two large iron ore mining centers in Brazil at the 2.6 GHz band. Although several studies focusing on radio propagation in underground mines have been published, measurement data and careful analyses for open-pit mines are still scarce. Our results aim at filling this gap in the literature. The research is motivated by the ongoing mine automation initiatives, where connectivity becomes critical. This paper presents the first set of results comprising measurements under a gamut of propagation conditions. A second paper detailing sub-GHz propagation is also in preparation. The results indicate that conventional wisdom is wrong, in other words, radio-frequency (RF) propagation in surface mines can be far more elaborate than plain free-space line-of-sight conditions. Additionally, the old mining adage “no two mines alike” seems to remain true in the RF domain.
04 Dec 2017
TL;DR: The results show that, in order to comply with ultra-reliable communications (URC) availability requirements, larger shadowing margins will have to be considered in the network planning in open-pit mines, when compared to traditional industrial environments.
Abstract: 5G will play a pivotal role in the digitization of the industrial sector and is expected to make the best use of every bit of spectrum available. In this light, this paper presents the results of an extensive measurement campaign in two iron-ore open-pit mining complexes, at the 700 MHz and 2.6 GHz bands, considering macro and small cell deployments. The study is further motivated by the rise of unmanned machinery in the mining industry. We present values of path loss exponents, shadow fading standard deviations, autocorrelation distances and inter-frequency cross-correlation, which are all useful for the future wireless network design, simulation and performance evaluation. The results show that, in order to comply with ultra-reliable communications (URC) availability requirements, larger shadowing margins will have to be considered in the network planning in open-pit mines, when compared to traditional industrial environments. Furthermore, large cross-correlation between the shadowing in both frequency bands limits the gains when using multi-connectivity in order to enhance overall network availability.
01 Oct 2017
TL;DR: A classification algorithm using existing LTE UE radio measurements to identify whether a UE is airborne or terrestrial is presented and it is shown that the method in 3 out of the 4 different measurement cases can detect a UE to be airborne with 99% likelihood.
Abstract: Unmanned Aerial Vehicles (UAVs) are expected to be connected through cellular networks As the radio characteristics are different for airborne UEs compared to terrestrial UEs, it is beneficial to identify whether a UE is airborne (on a UAV) or on the ground, such that interference and mobility management can be optimized for UAVs separately from terrestrial UEs In this paper, we present a classification algorithm using existing LTE UE radio measurements to identify whether a UE is airborne or terrestrial The method is verified with LTE measurements made in a rural area at different heights, including terrestrial measurements and it is shown that the method in 3 out of the 4 different measurement cases can detect a UE to be airborne with 99% likelihood, while the fourth case still can classify a UE correctly in 95% of the cases The right classification can further be improved by taking multiple consecutive samples into account before making a classification decision
21 May 2017
TL;DR: A thorough analysis of the achievable secrecy rate for a transceiver pair in FD mode in the presence of a passive eavesdropper assuming a generic system model and the ergodic secrecy rate is found to grow linearly with the log of the direct channel signal to noise ratio.
Abstract: Full duplex (FD) communication promises significant performance gains under ideal network settings. Generally, it has been shown that the throughput and delay gains of FD communication are somewhat limited in realistic conditions, leading researchers to study other possible applications where significantly higher gains over half duplex communication can be availed. The potential of FD nodes in improving the physical layer security of a communication link is investigated in this contribution. Specifically, we present a thorough analysis of the achievable secrecy rate for a transceiver pair in FD mode in the presence of a passive eavesdropper assuming a generic system model. The ergodic secrecy rate with FD communication is found to grow linearly with the log of the direct channel signal to noise ratio as opposed to the flattened out secrecy rate with conventional half duplex communication and irrespective of the eavesdropper channel strengths.
01 May 2017
TL;DR: The potential of full-duplex nodes in improving the physical-layer security of a communication link is investigated and the information-theoretic secrecy degrees of freedom measure for a pair of nodes communicating in full- duplex mode is derived.
Abstract: Full-duplex communication enables simultaneous transmission from both ends of a communication link, thereby promising gains in terms of the throughput and the delay. Such compelling gains are conditioned on a number of design constraints. Generally, it has been shown that the throughput gain and the delay reduction of full-duplex communication are conditioned on a number of assumptions. This has lead researchers to study other possible applications of full-duplex communication which can provide significantly higher gains over half-duplex communication in general. Physical-layer security is an example of such an application. The potential of full-duplex nodes in improving the physical-layer security of a communication link is investigated in this contribution. We specifically derive the information-theoretic secrecy degrees of freedom measure for a pair of nodes communicating in full-duplex mode. The secrecy degrees of freedom with full-duplex is shown to be two as opposed to that of zero in half-duplex mode. In addition, closed-form expressions for the instantaneous and ergodic throughput gain of full-duplex communication over conventional half-duplex are derived.
13 Nov 2017
TL;DR: This evaluation of the uplink performance of Sigfox and LoRa is evaluated in a controlled propagation environment (reverberation chamber) and shows that the proposed setup and testing methodology can be useful for comparing the many new wireless IoT technologies in a practical setting.
Abstract: In this study, the uplink performance of Sigfox and LoRa is evaluated in a controlled propagation environment (reverberation chamber). This evaluation is performed in terms of transfer error rate as a function of calibrated path loss, which allows a direct comparison of the performance of both systems under statistically similar propagation conditions. The analysis of the results shows that the proposed setup and testing methodology can be useful for comparing the many new wireless IoT technologies in a practical setting.
01 Jun 2017
TL;DR: The study takes into consideration the number of indoor cells deployed per floor, different inter-site distances (ISDs), transmit power settings and outdoor macro interference levels, and shows large variation in performance gain just by optimizing indoor cell locations.
Abstract: In this paper we set out to analyze the indoor capacity under a realistic high-rise building scenario. The study takes into consideration the number of indoor cells deployed per floor, different inter-site distances (ISDs), transmit power settings and outdoor macro interference levels. The outcome shows large variation in performance gain just by optimizing indoor cell locations, highlighting the need for thorough indoor radio planning. Investing into more indoor cells helps to increase capacity, and also to cope better with outdoor interference, but the gain tends to be diminishing due to the increase of inter-cell interference (ICI). Increasing transmit power brings largest gain when the density of indoor cell is low, and the noise and/or outdoor interference is the dominant source of performance degradation. When analyzing performance gain of an ideal receiver-side Interference Cancellation (IC) algorithm, the study also shows that, if the Dominant Interferer Removal (DIR) rate is below 50%, doubling the number of indoor cells would bring better capacity gain than investing into such an IC receiver.
01 Jun 2017
TL;DR: This paper proposes a new UW DFT-s-OFDM design which aims at exploiting such known sequence at the tail of the signal for tracking the variations of the radio channels on a symbol basis, thus overcoming the limited flexibility of DFT/OFDM waveforms in multiplexing reference sequences and data.
Abstract: Unique Word Discrete Fourier Transform -spread - Orthogonal Frequency Division Multiplexing (UW DFT-s-OFDM) waveform replaces the Cyclic Prefix (CP) with a known sequence which is contained in the symbol itself rather than being appended to it. In this paper, we propose a new UW DFT-s-OFDM design which aims at exploiting such known sequence at the tail of the signal for tracking the variations of the radio channels on a symbol basis, thus overcoming the limited flexibility of DFT-s-OFDM waveforms in multiplexing reference sequences and data. Further, we also present a criterion for efficiently selecting the reference sequences to be adopted by users experiencing fast time-varying channel conditions. Initial simulation results show the capability of the proposed design of improving the link performance of high speed users, even without additional overhead.
29 Jun 2017
TL;DR: An inter-cell rank coordination scheme whereby a serving base station coordinates the preferred maximum interference rank with the dominant interfering BS through exchange of coordination messages over the Xn interface is proposed.
Abstract: Multiple receive and transmit antennas can be used to improve the spectral efficiency by transmitting over multiple independent streams. In addition, multiple receive antennas facilitate interference suppression through the use of interference rejection combining receivers. Rank adaptation algorithms are aimed at balancing the trade-off between increasing the spatial gain, and improving the interference resilience property. In this paper, we propose an inter-cell rank coordination scheme whereby a serving base station coordinates the preferred maximum interference rank with the dominant interfering BS through exchange of coordination messages over the Xn interface. The proposed scheme is computationally efficient and requires minimum control overhead. Matlab based system-level simulation results indicate around 65% gain in terms of the outage throughput with little impact on the peak user throughput.