Unlicensed Devices Research Articles

Deep Learning for Path Loss Prediction at 7 GHz in Urban Environment

In the 6 GHz spectrum sharing band, unlicensed devices are managed by automated frequency coordination (AFC) systems to protect incumbent services from interference. Thus, it is important to select accurate propagation models for interference calculation and analysis. This paper utilizes a model-aided deep learning technique for path loss prediction at 7 GHz, as a representative frequency within the 6 GHz band, in an urban environment. The proposed model is a hybrid model, which leverages both domain expert knowledge from a physics-based general-purposed channel model as well as the learning-based capability from a neural network, for path loss prediction. The model is trained and tested using sufficient-quantity and high-quality real propagation measurement data collected in four locations in an urban environment. Numerical results show that the deep learning model provides a better prediction performance than most empirical models. Furthermore, the feasibility of proposed model generalization to new locations after fine-tuning is examined.

ML-Based Classification of Device Environment Using Wi-Fi and Cellular Signal Measurements

Future spectrum sharing rules very likely will be based on device environment: indoors or outdoors. For example, the 6 GHz rules created different power regimes for unlicensed devices to protect incumbents: “indoor” devices, subject to lower transmit powers but not required to access an Automatic Frequency Control database to obtain permission to use a channel, and “outdoor” devices, allowed to transmit at higher power but required to do so to determine channel availability. However, since there are no reliable means of determining if a wireless device is indoors or outdoors, other restrictions were mandated: reduced power for client devices and indoor access points that cannot be battery powered, have detachable antennas or be weatherized. These constraints lead to sub-optimal spectrum usage and potential for misuse. Hence, there is a need for robust identification of device environments to enable spectrum sharing. In this paper we study automatic indoor/outdoor classification based on the radio frequency (RF) environment experienced by a device. Using a custom Android app, we first create a labeled data set of a number of parameters of Wi-Fi and cellular signals in various indoor and outdoor environments, and then evaluate the classification performance of various machine learning (ML) models on this data set. We find that tree-based ensemble ML models can achieve greater than 99% test accuracy and F1-Score, thus allowing devices to self-identify their environment and adapt their transmit power accordingly.

Triple-step feed line-based compact ultra-wideband antenna with quadruple band-notch characteristics

ABSTRACT An ultra-wideband (UWB) antenna with quadruple-band-rejection characteristics and a size-miniaturised approach for portable wireless applications is designed and experimentally investigated. The proposed antenna consists of a unique trapezoidal-shaped patch, 50 Ω triple-step microstrip feed line and step–truncated ground plane. The patch tapering improves the bandwidth of an antenna to 2.8–12.5 GHz with fractional–bandwidth of 127%, covering an entire UWB (3.1–10.6 GHz). Consequently, it provides a nearly omnidirectional radiation pattern, better gain and excellent radiation efficiency. The three steps of the feed line increase the electrical length of the patch, achieving size reduction of the fabricated antenna to 20 mm × 29 mm. Generally, UWB systems suffer owing to strong narrowband signal interference from unlicensed wireless communication devices. To avoid this, the proposed antenna is designed with quadruple band-notch characteristics. It includes three inverted U-slots (length approaches half the guided wavelength), which are used to reject the 3.5, 4.5 and 5.2/5.8 GHz bands. Moreover, a C-strip pair besides the feed line is used to reject the 8.35 GHz X-band. The simulated results were also compared with the experimental performance of the prototype in terms of reflection coefficient, voltage standing wave ratio, radiation pattern, transfer function, group delay and gain of the antenna.

WITHDRAWN: An extensive survey on cognitive radio based spectrum sensing using different algorithms

Abstract Latest technical developments also emerged in the implementation of wireless networks which consisting of self-organizing devices which can be distributed without finding for infrastructure. Usually these devices having small form factor and also stored with embedded devices, ability of communication and processing. The licensing of wireless spectrum is highly developed over large global locations on a basis of long-term. The FFC was recently implemented the usage of unlicensed devices in licensed bands in order to overcome the significant problems of spectrum scarcity. Dynamic spectrum access (DSA) strategies are therefore suggested to address the existing issues of spectrum inefficiency. In order to further boost spectrum quality; this new research area has recognized the creative network called Cognitive Radio (CR). The fundamental principle of CR network is that the unlicensed network (secondary users) must vacate the band until the licensed network (primary user) is sensed. However, due to the high variations which are available in the spectrum and (QoS) criteria, the CR network will able to face different challenges.

Methods of evaluation and forecasting of levels of electromagnetic radiation in urban environments (in Ukrainian)

Abstract: This article is devoted to the decision of the actual scientific and applied problem which consists in the development of a method of definition of levels of the basic and secondary electromagnetic radiations in the urban environments at the expense of perfection of models of their distribution. The necessity in the increased efficiency of use of devices of monitoring of an electromagnetic situation on the basis of the analysis of features of distribution of electromagnetic radiations in the urban environment and lacks of the existing mathematical device for their description is proved. The nature of the interference and the distance in real operating conditions and the corresponding graphical and mathematical dependences were obtained, which formed the basis of the method of improving the models of electromagnetic radiation propagation. Scientific methods of synthesis of the detailed structural scheme of processes of detection and localization of uncontrolled and unlicensed devices of information transmission on radio channels, including development Bakhtiiarov, D.I., Lavrynenko, O.Y., Lishchynovska, N.O., Komarnytskyi, O.O. (2020). Methods of evaluation and forecasting of levels of electromagnetic radiation in urban environments (in Ukrainian). Actual issues of modern science. No. 1. Vol. 2, add. Collection of Scientific Articles, 06-2 (06), __- __. European Scientific e-Journal. Hlučín-Bobrovníky: “Anisiia Tomanek” OSVČ. ESEJ: inn2020-12-001 DOI: 10.47451/inn2020-12-001 Бахтіяров, Д.I., Лавриненко, O.Ю., Ліщиновська, Н.O., Комарницький, O.O. (2020). Методи оцінювання та прогнозування рівнів електромагнітних випромінювань в урбанізованих середовищах. Actual issues of modern science. No. 1. Vol. 2, add. Collection of Scientific Articles, 06-2 (06), __-__. European Scientific e-Journal. Hlučín-Bobrovníky: “Anisiia Tomanek” OSVČ. 2 of the software for definition of a zone of electromagnetic accessibility indoors are substantiated. An original approach, algorithm of functioning and methods of synthesis of search means in the conditions of radio interference and detection of sources of electromagnetic radiation are developed. Key words: secondary electromagnetic radiation; electromagnetic reach; radio wave propagation; Hut model; COST 231 MWM; monitoring of the electromagnetic environment, attenuation factor

Next Generation Wi-Fi and 5G NR-U in the 6 GHz Bands: Opportunities and Challenges

The ever-increasing demand for unlicensed spectrum has prompted regulators in the US and Europe to consider opening up the 6 GHz bands for unlicensed access. These bands will open up 1.2 GHz of additional spectrum for unlicensed radio access technologies (RATs), such as Wi-Fi and 5G New Radio Unlicensed (NR-U), in the US and if permitted, 500 MHz of additional spectrum in Europe. The abundance of spectrum in these bands creates new opportunities for the design of mechanisms and features that can support the emerging bandwidth-intensive and latency-sensitive applications. However, coexistence of unlicensed devices both with the bands' incumbent users and across different unlicensed RATs present significant challenges. In this paper, we provide a comprehensive survey of the existing literature on various issues surrounding the operations of unlicensed RATs in the 6 GHz bands. In particular, we discuss how key features in next-generation Wi-Fi are being designed to leverage these additional unlicensed bands. We also shed light on the foreseeable challenges that designers of unlicensed RATs might face in the near future. Our survey encompasses key research papers, contributions submitted to standardization bodies and regulatory agencies, and documents presented at various other venues. Finally, we highlight a few key research problems that are likely to arise due to unlicensed operations in the 6 GHz bands. Tackling these research challenges effectively will be critical in ensuring that the new unlicensed bands are efficiently utilized while guaranteeing the interference-free operation of the bands' incumbent users.

Primary User Avoidance algorithm for CRAHNs using Reinforcement Learning

Cognitive Radio Ad Hoc Networks (CRAHNs) are the need of the current time. There is a requirement of providing accessibility of network “everywhere”. This “everywhere” connectivity to all kinds of unlicensed devices is very hard to achieve in statically allocated spectrum bands. So CRAHNs were envisioned. In CRAHNs, it is very important to protect transmission of primary user. This paper tries to handle this concern. A reinforcement learning based algorithm is proposed and implemented which protects the transmission of primary user by avoiding secondary users to enter primary user coverage area, which is not known in advance. This algorithm will learn from its experience & once it has learnt from its environment, it always tries to avoid primary user within a region where primary user is operating on same channel as secondary user. This work includes Q learning along with neural networks (implemented in python). The experimentations results proved that this algorithm learns over time, because as the number of epochs are increased loss rate tends to decline. The algorithm is executed using neural networks with varying schemes. All of them proved that there is worthy amount of learning with decent accuracy. Results drawn from the proposed algorithm yield as output the distance covered by secondary user in each configuration, without hitting primary user and the mean loss rate for each configuration. The algorithm proposed in this paper is anticipated to be durable and robust. Moreover, it can work on large networks as well.

Spectrum for V2X: Allocation and Sharing

This paper investigates how much spectrum should be available for intelligent transportation systems (ITS), and whether part of that spectrum should be shared with unlicensed devices, as has been considered by the U.S. Federal Communications Commission (FCC), and if so, what sharing scheme should be adopted. We found that the ITS bandwidth that maximizes social welfare could be either much more or much less than what has already been allocated, because optimal bandwidth is sensitive to uncertain factors, such as device penetration, future data rates, and spectrum opportunity cost. That uncertainty is offset if ITS spectrum is shared under a scheme of coexistence among equals. We also found that the bandwidth required to obtain given throughputs on shared spectrum can be considerably less than the bandwidth to obtain the same throughputs in separate bands. We conclude that the spectrum available for ITS should be maintained or increased, but much of ITS spectrum should be shared with non-ITS devices.

Part 15++: An Enhanced ID-Based Approach for Etiquette and Enforcement Management in Unlicensed Band

The simple and well-conceived global rules for the unlicensed bands operating in the industrial, scientific, and medical (ISM) band has enabled tremendous product and service innovation. However, the argument can be made that the growing use of unlicensed bands by greater numbers and more heterogenous devices could lead to certain “tragedies of the commons.” The current regulatory approach limits how devices may operate in space-time–frequency along with restriction on transmit power, antenna specification and synchronization. However, if these devices could be better informed about an impending interference through simple alterations to the regulations, then it might be possible to improve both device and overall use of the spectrum. Thus, we propose Part 15++, where unlicensed devices make use of an enhanced identification (ID) mechanism to identify the operator, interferer, victim, and resolution mechanism for a system. With denser and broader use of these bands, we show that creating a common ID method might allow for a more efficient coexistence among heterogeneous technologies. Admittedly, there are numerous benefits and costs to consider with the proposed ID extension, but in this paper, we explore improving throughput followed by a sensitivity analysis on the information provided in the ID structure.

A comprehensive survey on networking over TV white spaces

TV white spaces refer to the allocated but locally unused TV spectrum and can be used by unlicensed devices as secondary users. Thanks to their lower frequencies (e.g., 54–698 MHz in the US), communication over the TV spectrum has excellent propagation characteristics over long distances and through obstacles. These characteristics along with their wide availability make the TV white spaces a great choice and alternative to many existing wireless technologies, especially the ones that need long range and high bandwidth communication. In the last decade, there have been numerous efforts from academia, industries, and standards bodies for exploiting the potentials of the TV white spaces for several applications including wireless broadband Internet access. Their characteristics and features also hold potentials for many new applications including sensing and monitoring, Internet of Things, wireless control, smart utility, location-based services, and transportation and logistics. In this paper, we perform a retrospective review and comparative study of existing work on networking in the TV white spaces. Additionally, we discuss the associated research challenges such as dealing with the interference between primary and secondary TV spectrum users, TV white space temporal and spatial variations and fragmentation, antenna design, mobility, and security. We also describe the future research directions to handle the above challenges. To the best of our knowledge, this is the first comprehensive survey on the literature of TV white space networking research.

The Medical Devices Special Access Program in Canada: A Scoping Study.

New health technologies enter Canadian healthcare organizations in various ways, and understanding them is essential to the development of a pan-Canadian Health Technology Management (HTM) Strategy, now a priority of governments across Canada. One way is through Health Canada's Medical Devices Special Access Program (MDSAP), which permits unlicensed devices to be obtained by healthcare professionals. However, the circumstances around and implications of the current use of this program are not clear. A scoping literature review was conducted to clarify these and identify important roles and issues related to the MDSAP. Limited information was found on the MDSAP. Nevertheless, three themes demonstrating the roles of the MDSAP in HTM emerged: arbiter in technology selection, a route to technology procurement and facilitator of health technology innovation. No information suggesting that MDSAP is used to circumvent licensing was found. Rather, it enables desired patient outcomes and product commercialization.

Coexistence of Wireless Technologies in the 5 GHz Bands: A Survey of Existing Solutions and a Roadmap for Future Research

As the 2.4 GHz spectrum band has become significantly congested, there is growing interest from the Wi-Fi proponents, cellular operators, and other stakeholders to use the spectrum in the 5 GHz bands. The 5 GHz bands have emerged as the most coveted bands for launching new wireless applications and services, because of their relatively favorable propagation characteristics and the relative abundance of spectrum therein. To meet the exploding demand for more unlicensed spectrum, regulators across the world such as the United States Federal Communications Commission and the European Electronic Communications Committee have recently started considerations for opening up additional spectrum in the 5 GHz bands for use by unlicensed devices. Moreover, to boost cellular network capacity, wireless service providers are considering the deployment of unlicensed long term evaluation (LTE) in the 5 GHz bands. This and other emerging wireless technologies and applications have resulted in likely deployment scenarios where multiple licensed and unlicensed networks operate in overlapping spectrum. This paper provides a comprehensive overview of the various coexistence scenarios in the 5 GHz bands. In this paper, we discuss coexistence issues between a number of important wireless technologies—viz., LTE and Wi-Fi, radar and Wi-Fi, dedicated short range communication (DSRC) and Wi-Fi, and coexistence among various 802.11 protocols operating in the 5 GHz bands. Additionally, we identify and provide brief discussions on an impending coexistence issue—one between Cellular V2X and DSRC/Wi-Fi. We summarize relevant standardization initiatives, explain existing coexistence solutions, and discuss open research problems.

Feasibility Investigation on Cognitive Radio Network Systems: Hearsay Algorithm

In this paper Specifies, how effectively utilization of radio spectrum is important for accommodating the rapid growth of wireless communications. Cognitive Radio (CR) refers to a wireless architecture that enables dynamic spectrum access, where unlicensed devices are allowed to operate in temporally/spatially unused licensed channels. The main challenge for CR is a robust protection mechanism to guarantee an adequate Licensed Users (LU) system performance at all times. This requires a reliable spectrum sensing technique to accurately identify frequency opportunities; and an autonomous transmit power control algorithm that remains effective in severe fading environments. Cooperation among CR devices to assist the LU identification process is shown to be an imperative CR attribute for maximising the CR performance and the overall spectral utilisation The Hearsay Algorithm is a novel Transmit Power Control algorithm for CRs in a cooperative network. Each node seeking to transmit is informed of the status of the LU channel by a chain of other CR nodes, hence the term “Hearsay”.

A Hierarchical Spectrum Access Scheme for TV White Space Coexistence in Heterogeneous Networks

Among current techniques for dynamic access to television (TV) white space (TVWS), geolocation database-based access provides a promising performance in protecting the TV-band incumbents from interference that cannot be efficiently achieved in other license-exempt models. However, in heterogeneous wireless networks, most portable devices do not have such access and may cause interference to TV incumbents. We propose a hierarchical model for spectrum sharing in TVWS that includes a wide range of fixed and portable devices. In the first tier, the TV broadcaster can lease the spectrum bands to local fixed users based on a soft license agreement. The fixed users are allowed to share access to this spectrum with some mobile users in their proximity in exchange for cooperative relaying. We consider a practical scenario, where only partial channel state information (CSI) is available at the users’ transmitters, and we propose a robust algorithm against such uncertainties in CSI values. We also propose a reputation-based relay selection mechanism to identify selfish portable users. The proposed spectrum sharing framework can provide a practical model for TVWS-coexistence that prevents undesired interference to the incumbents while restricting interference among the unlicensed devices. The simulation results show the enhancement of fixed users’ rate compared with alternative relay selection methods.

Database-Assisted Distributed and Cloud-Based Access Methods for Unlicensed and Radar Bands

This paper focuses on the design of methods which enable unlicensed devices to use the frequency spectrum already allocated to rotating radar systems without causing interference to those radars. We first present a database-assisted spectrum sharing/co-existence mechanism for radar spectrum bands. This mechanism takes into account the real spectrum usage behavior of different radars, and is also implemented by prototyping a real-time rotating radar beam emulator, a radar spectrum database using MySQL software, and spectrum access algorithm on wireless open access research platform. Then we propose a cloud-based unified channel access (UCA) method and a distributed UCA method for co-existence of multiple competing users in unlicensed and rotating radar spectrum bands. We model the UCA problem as a game and propose iterative methods (i.e., algorithms) to obtain the solution of the game. We study the stability of the proposed methods under several different scenarios. We show that the proposed UCA game is a potential game, and also show that the proposed methods guarantee convergence to a Nash equilibrium. Our results show that the cloud-based method allows fast convergence and can achieve performance that is close to optimal solution.

Multilevel Protection to Broadcaster Contour and Its Impact on TV White Space Availability

In light of recent regulations from the Federal Communications Commission (FCC) governing the very-high-frequency/ultrahigh-frequency band sharing, we consider the database as a tool to plan the utilization of this spectrum by unlicensed wireless devices. Our approach, however, differs from that adopted by the FCC in the sense that it exploits the ability that white space (WS) devices have in controlling their effective isotropic radiated power through the transmit power control technique when concomitantly operating in a cochannel or in an adjacent channel to a TV station. We derive equations for the expected interference level generated by WS devices with antenna heights ranging from a few meters (portable devices) up to a 1000 m (fixed devices) based on very recent TV white space (TVWS) propagation literature and regulatory requirements. Additionally, we also provide exact and numerical methods to calculate the critical distance that prevents interference to primary contours, thus enabling fast identification of regions where operation is harmless to incumbents in the presence of shadowing and multipath fading. These equations reveal the intrinsic relationship between system design parameters, environmental parameters, and country regulations with TVWS availability. Finally, we provide an analysis that indicates notable enhancements in the expected TVWS availability through the use of a multilevel method while obtaining the same desirable degree of protection required by the current FCC regulation based on the single-level methodology. The analysis is divided in two parts: theoretical evaluations to obtain insights into the potential of multilevel protection in recovering TVWS-less regions from a single exclusion zone and extensive computations to obtain the expected TVWS availability yielded by both protection methodologies and primary-contour determination techniques across the Japanese territory. Specifically, multilevel protection is found to have the effect of doubling the TVWS bandwidth, as compared with single-level protection. On the other hand, diffraction methods used to determine the primary contour nearly triples the bandwidth, as compared with the height above average terrain (HAAT) technique. The combined effect of multilevel protection and diffraction-based primary contours is TVWS availability on 98.76% of the Japanese territory with a bandwidth expansion six times of that inherent to single-level protection and HAAT-based contours.

Analysis on Coexistence between Unlicensed Wireless Device based on 802.11ah and LTE User Equipment

Analysis on Coexistence between Unlicensed Wireless Device based on 802.11ah and LTE User Equipment

Spectrum sharing between a surveillance radar and secondary Wi-Fi networks

Co-existence between unlicensed networks that share a spectrum spatio-temporally with terrestrial (e.g., Air Traffic Control) and shipborne radars <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> in 3 GHz band is attracting significant interest. Similar to every primary-secondary coexistence scenario, interference from unlicensed devices to a primary receiver must be within acceptable bounds. In this work, we formulate the spectrum sharing problem between a pulsed, search radar (primary) and 802.11 wireless local area network (WLAN) as the secondary.We compute the protection region for such a search radar for a single secondary user (initially) as well as a random spatial distribution of multiple secondary users. Furthermore, we also analyze the interference to the Wi-Fi devices from the radar's transmissions to estimate the impact on achievable WLAN throughput as a function of distance to the primary radar.

Pricing Model for TV White Spaces Channels With Different Priorities

A new type of TV white space (TVWS) channel called the high priority channel (HPC) has been proposed by the regulator of Singapore. The HPCs are TVWS channels that will always be available to unlicensed white space devices (WSDs) although a white space database (WSDB) provider may impose fees to WSDs for using HPCs. The HPC is of interest to WSDB providers since it creates a new business opportunity for them. In this letter, we investigate the optimal fee for using HPCs such that the WSDB provider achieves the maximum revenue. The solution of the optimal fee is provided in this letter. From this study, it is observed that WSDB provider should not always increase the fee when the total number of WSDs increases as our results show that sometimes lowering the fee to attract more WSDs to use HPCs actually increases the revenue.

비면허기기 간 실시간 주파수간섭 분석 테스트베드 구현

본 논문에서는 2.4 GHz 대역에서 동작하는 Wi-Fi나 Zigbee 등 비면허기기 간 주파수간섭을 실시간으로 분석할 수 있는 테스트베드를 제안하였다. 제안된 테스트베드는 피간섭원과 간섭원의 RF부는 범용 SDR 보드인 Universal Software Radio Peripheral(USRP)로 구현하고, 모뎀은 <TEX>$Labview^{TM}$</TEX>를 이용하여 프로그램하여 구현하였다. 따라서 주파수간섭과 관련된 동작 주파수, 출력전력, 모뎀 파라미터 등을 손쉽게 변경할 수 있어 다양한 주파수간섭 환경을 손쉽게 모델링할 수 있을 뿐만 아니라, 주파수간섭에 따른 물리계층의 Bit Error Rate(BER) 열화 특성을 실시간으로 파악할 수 있는 장점이 있다. 테스트베드의 검증을 위해 피간섭원으로 IEEE 802.15.4를, 간섭원으로 IEEE 802.11b를 구현하여 실시간으로 주파수간섭 영향을 측정하고, 이를 이론 및 MATLAB/Simulink 시뮬레이션 결과와 비교하여 1 dB 이내로 일치함을 확인하였다. In this paper, we suggested a real-time test-bed for analyzing frequency interference between 2.4 GHz unlicensed devices, such as WiFi, Zigbee, etc. Owing to versatile programming capability of Universal Software Radio Peripheral(USRP) and <TEX>$Labview^{TM}$</TEX>, frequency interference environments can be easily modeled. Therefore, performance degradation effects due to various parameters of interferer and victim receiver can be analyzed intuitively. For verification, we showed a frequency interference scenario, which consists of IEEE 802.15.4 as a victim and IEEE 802.11b as a interferer. Measured Bit Error Rate(BER) results showed good agreement with theory and simulation results.