There is considerable pressure to define the key requirements of 5G, develop 5G standards, and perform technology trials as quickly as possible. Normally, these activities are best done in series but there is a desire to complete these tasks in parallel so that commercial deployments of 5G can begin by 2020. 5G will not be an incremental improvement over its predecessors; it aims to be a revolutionary leap forward in terms of data rates, latency, massive connectivity, network reliability, and energy efficiency. These capabilities are targeted at realizing high-speed connectivity, the Internet of Things, augmented virtual reality, the tactile internet, and so on. The requirements of 5G are expected to be met by new spectrum in the microwave bands (3.3-4.2 GHz), and utilizing large bandwidths available in mm-wave bands, increasing spatial degrees of freedom via large antenna arrays and 3-D MIMO, network densification, and new waveforms that provide scalability and flexibility to meet the varying demands of 5G services. Unlike the one size fits all 4G core networks, the 5G core network must be flexible and adaptable and is expected to simultaneously provide optimized support for the diverse 5G use case categories. In this paper, we provide an overview of 5G research, standardization trials, and deployment challenges. Due to the enormous scope of 5G systems, it is necessary to provide some direction in a tutorial article, and in this overview, the focus is largely user centric, rather than device centric. In addition to surveying the state of play in the area, we identify leading technologies, evaluating their strengths and weaknesses, and outline the key challenges ahead, with research test beds delivering promising performance but pre-commercial trials lagging behind the desired 5G targets.

5G : A tutorial overview of standards, trials, challenges, deployment, and practice

Low power wide area (LPWA) networks are attracting a lot of attention primarily because of their ability to offer affordable connectivity to the low-power devices distributed over very large geographical areas. In realizing the vision of the Internet of Things, LPWA technologies complement and sometimes supersede the conventional cellular and short range wireless technologies in performance for various emerging smart city and machine-to-machine applications. This review paper presents the design goals and the techniques, which different LPWA technologies exploit to offer wide-area coverage to low-power devices at the expense of low data rates. We survey several emerging LPWA technologies and the standardization activities carried out by different standards development organizations (e.g., IEEE, IETF, 3GPP, ETSI) as well as the industrial consortia built around individual LPWA technologies (e.g., LoRa Alliance, Weightless-SIG, and Dash7 alliance). We further note that LPWA technologies adopt similar approaches, thus sharing similar limitations and challenges. This paper expands on these research challenges and identifies potential directions to address them. While the proprietary LPWA technologies are already hitting the market with large nationwide roll-outs, this paper encourages an active engagement of the research community in solving problems that will shape the connectivity of tens of billions of devices in the next decade.

Low Power Wide Area Networks: An Overview

LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central network server. This paper provides an overview of LoRa and an in-depth analysis of its functional components. The physical and data link layer performance is evaluated by field tests and simulations. Based on the analysis and evaluations, some possible solutions for performance enhancements are proposed.

https://www.mdpi.com/1424-8220/16/9/1466/pdf

A Study of LoRa: Long Range & Low Power Networks for the Internet of Things

The Internet of Things (IoT) is a promising technology which tends to revolutionize and connect the global world via heterogeneous smart devices through seamless connectivity. The current demand for machine-type communications (MTC) has resulted in a variety of communication technologies with diverse service requirements to achieve the modern IoT vision. More recent cellular standards like long-term evolution (LTE) have been introduced for mobile devices but are not well suited for low-power and low data rate devices such as the IoT devices. To address this, there is a number of emerging IoT standards. Fifth generation (5G) mobile network, in particular, aims to address the limitations of previous cellular standards and be a potential key enabler for future IoT. In this paper, the state-of-the-art of the IoT application requirements along with their associated communication technologies are surveyed. In addition, the third generation partnership project cellular-based low-power wide area solutions to support and enable the new service requirements for Massive to Critical IoT use cases are discussed in detail, including extended coverage global system for mobile communications for the Internet of Things, enhanced machine-type communications, and narrowband-Internet of Things. Furthermore, 5G new radio enhancements for new service requirements and enabling technologies for the IoT are introduced. This paper presents a comprehensive review related to emerging and enabling technologies with main focus on 5G mobile networks that is envisaged to support the exponential traffic growth for enabling the IoT. The challenges and open research directions pertinent to the deployment of massive to critical IoT applications are also presented in coming up with an efficient context-aware congestion control mechanism.

A Survey on 5G Networks for the Internet of Things: Communication Technologies and Challenges

This paper provides an overview of the features of fifth generation (5G) wireless communication systems now being developed for use in the millimeter wave (mmWave) frequency bands. Early results and key concepts of 5G networks are presented, and the channel modeling efforts of many international groups for both licensed and unlicensed applications are described here. Propagation parameters and channel models for understanding mmWave propagation, such as line-of-sight (LOS) probabilities, large-scale path loss, and building penetration loss, as modeled by various standardization bodies, are compared over the 0.5–100 GHz range.

/pdf/overview-of-millimeter-wave-communications-for-fifth-3yhmjybx4f.pdf

Overview of Millimeter Wave Communications for Fifth-Generation (5G) Wireless Networks—With a Focus on Propagation Models

In addition to long battery life and low cost, coverage is one of the most critical performance metrics for the low power wide area networks (LPWAN). In this work we study the coverage of the recently developed LoRa LPWAN technology via real-life measurements. The experiments were conducted in the city of Oulu, Finland, using the commercially available equipment. The measurements were executed for cases when a node located on ground (attached on the roof rack of a car) or on water (attached to the radio mast of a boat) reporting their data to a base station. For a node operating in the 868 MHz ISM band using 14 dBm transmit power and the maximum spreading factor, we have observed the maximum communication range of over 15 km on ground and close to 30 km on water. Besides the actual measurements, in the paper we also present a channel attenuation model derived from the measurement data. The model can be used to estimate the path loss in 868 MHz ISM band in an area similar to Oulu, Finland.

On the coverage of LPWANs: range evaluation and channel attenuation model for LoRa technology

The main objective of this paper is to present major challenges regarding the fifth generation (5G) mobile communications propagation modelling work in the European 7
 th
 framework project METIS (Mobile and wireless communications Enablers for the Twenty-twenty Information Society). The goal of the propagation work in METIS is to provide adequate propagation models for 5G. For this purpose corresponding deficiencies of present commonly used models are identified. Further, the lack of available channel models for several propagation scenarios has been assessed. Based on this assessment the framework of 5G channel modelling is sketched. As propagation measurement campaigns are a crucial part of this work they are illustrated with a few examples.

Channel modelling for the fifth generation mobile communications

This article first identifies requirements of 5G radio propagation models for relevant propagation scenarios and link types derived from the analysis of recently discussed 5G visions and respective 5G technology trends. A literature survey reveals that none of the state-of-the-art propagation models such as WINNER/IMT-Advanced, COST 2100, and IEEE 802.11 fully satisfies the model requirements without significant extensions, and therefore there is room for a new framework of propagation models. We then present a novel map-based propagation model that satisfies the model requirements, and also introduce new extensions to existing stochastic models. Several open issues are finally identified that require further studies in 5G propagation modeling.

Radio propagation modeling for 5G mobile and wireless communications

Applicability of cognitive radio (CR) techniques to satellite communications is investigated and classification for the possible applications is foreseen in this paper. The proposed application scenarios include a) secondary use of satellite spectrum by a terrestrial system, b) secondary use of terrestrial spectrum by a satellite system, and c) a hybrid scenario where terrestrial network coverage is expanded by the use of satellite spots. Key challenges and enabling technologies for each scenario are discussed. Link budget analyses and system simulations are used to define operational limits for interference management in the mentioned scenarios regarding spectrum sensing, transmission power control, and directional antennas. The results show that CR techniques should be applied with caution in satellite bands. However, obvious potential to improve the spectrum efficiency can be seen in each scenario.

Application of cognitive radio techniques to satellite communication

Frequency-agile pathloss models for urban street canyons are discussed in this paper. The models are floating intercept (FI), fixed reference (FR), and ITU-R M.2135 urban microcellular (UMi) line-of-sight (LOS) and Manhattan-grid non-LOS (NLOS) models. These models are parameterized based on channel sounding campaigns in three cities covering radio frequencies ranging from 0.8 to 60 GHz. Fitting the models with measured pathloss reveals that the models are usable to cover the considered frequency range. The FI and FR models are equally simple and robust, with a slight advantage of the FI model in accuracy because of the larger number of model parameters. The original M.2135 LOS model is based on a two-ray model that includes a break point (BP). The model is extended for a better fit with measurements by including new model parameters such as a pathloss offset and a BP scaling factor that represent local scattering conditions of surrounding environments. The new model parameters are found frequency dependent in many cases. The original M.2135 model is furthermore simplified in NLOS scenarios while maintaining the model accuracy. The model parameters are derived using maximum likelihood estimation, which also showed that the modified M.2135 model offers up to 50% better accuracy compared to the FI and FR models in terms of the employed log-likelihood function (LLF). The improvement in accuracy is particularly remarkable in NLOS scenarios. A full set of parameters is provided for the models, allowing a choice for any given requirements on accuracy and complexity. Finally, applicability of the proposed models to other street canyons is discussed using independent pathloss measurements.

Antti Roivainen

Papers

On the coverage of LPWANs: range evaluation and channel attenuation model for LoRa technology

Channel modelling for the fifth generation mobile communications

Radio propagation modeling for 5G mobile and wireless communications

Application of cognitive radio techniques to satellite communication

Frequency-Agile Pathloss Models for Urban Street Canyons