Fixed Service Research Articles

Spectrum Sharing of HAPS and Fixed Link in Millimeter Waves

A High Altitude Platform System (HAPS) is an emerging technology that can potentially bring connectivity to areas that are not partially or totally covered by cellular networks. However, allocating certain frequency bands for the HAPS alongside wireless Fixed Service (FS) imposes some restrictions on operating the HAPS systems to ensure no interference occurs between the two systems (HAPS and FS). This paper presents an analytical study of the spectrum sharing between the HAPS and the FS in millimeter waves, namely in 38- and 47-GHz bands. Some potential and significant interference scenarios have been applied in order to investigate the spectrum-sharing situations in urban and suburban areas. The Carrier to Interference plus Noise Ratio (CINR) has been adopted as the main criterion to assess the performance of the HAPS. It is found that the HAPS and FS systems can simultaneously share the 38- and 47-GHz bands with some restrictions to HAPS altitude, allowable CINR, and location of the HAPS user. These restrictions differ depending on the area coverage type.

A spectrally efficient service apportionment method for sharing and compatibility studies

A key aspect of radio spectrum sharing and compatibility studies is the modelling of interference levels seen by the receivers of one service from the transmitters of another service. In general, calculated interference levels must be below predetermined interference thresholds for sharing or compatibility to be considered feasible. Sometimes, the modelling must take account of interference sourced from services operating in the spectrum but not directly under investigation in the study. This may be done by apportioning the interference thresholds for a particular service between other radio services using, or with potential to use, the spectrum; a method termed service apportionment. Traditionally, equal apportionments for those services with the same regulatory status has been assumed. This is very simple but not necessarily spectrally efficient and may overestimate or underestimate the contribution to aggregate interference. This paper sets out an alternative approach. The apportionment assigned to the emerging IMT service is based on an analysis of the established radio interference environment. Specifically: the aggregate interference sourced from a deployment of fixed service (FS) links incident to a satellite receiver. Our analysis shows that the FS links under-utilise the conventional equal apportionment allowing for an inequality between the service apportionments assigned to IMT and FS and greater potential for a solution to this particular compatibility problem.

Performance of the DBS Satellite Receiver under the Impact of Rainfall and Terrestrial Interference

This article presents a new study on the feasibility of operating a direct broadcasting satellite (DBS) system under the effect of both precipitation and interference from a fixed service (FS) at K‐band in a semiarid region. The carrier‐to‐noise plus interference ratio (CNIR) as a protection criterion has been adopted to make sure that the receiver of the DBS system operates with an acceptable performance under rainfall and interference from FS. Various measured data for rainfall in different areas have been utilized to investigate different rain rate exceedance percentages. Results have been shown that areas with high rain rates have a small CNIR at the DBS receiver and require large protection distances compared to low‐rain rate areas and vice versa. Some mitigation techniques have been suggested to alleviate the effect of rain and terrestrial interference on the DBS receiver performance.

Numerical approximation of millimeter-wave frequency sharing between cellular systems and fixed service systems

This paper presents numerical analysis and simulation results in order to study the impact of interference between fixed service (FS) systems and 5G cellular networks at 28 GHz, 38 GHz, and 60 GHz millimeter-wave (mmWave) bands. For this study, two different scenarios were considered, i.e., the aggregation of interference from small cells into an FS receiver from (i) base stations (BSs) to their associated user equipment (UE) (downlink); (ii) from UEs to their associated BSs (uplink). The simulation results determined how much interference rejection is required to protect the operation of the FS. This study is essential when using mmWave technologies in cellular networks, to determine whether the newly deployed cellular systems can co-exist with pre-deployed FS systems or not. This paper presents closed-form numerical approximation results with Taylor series approximation along with intensive simulation results. Finally, this paper confirmed that the numerical approximation results were precise, i.e., that here were only marginal differences to the intensive simulation results.

Performance Limits of Cognitive-Uplink FSS and Terrestrial FS for Ka-Band

This paper investigates the performance limits of cognitive-uplink fixed satellite service (FSS) and terrestrial fixed service (FS) operating in the range 27.5–29.5 GHz for Ka-band. In light of standard recommendations from the International Telecommunications Union and a rain-fading channel model, we analyze the interference level at the FS receiver by considering statistical properties of the channel, propagation losses, and antenna patterns. By employing the interference constraint criterion at the FS, an analytical expression for the capacity of the cognitive-uplink FSS is derived, which is useful in understanding the limits in performance and the potential application of the considered coexistence scenario. Simulations are carried out to verify the theoretical derivations and highlight the impact of key parameters on the performance limits.

Spectrum-Sharing Method for Co-Existence Between 5G OFDM-Based System and Fixed Service

This study investigates the co-existence of fifth generation (5G) mobile communication systems and fixed service (FS) in the 28-GHz band through the utilization and modification of an existing spectrum-sharing method known as the advanced minimum coupling loss (A-MCL) model. The proposed model is based on the power spectral density (PSD) overlap between the 5G orthogonal frequency-division multiplexing (OFDM)-based system and the FS. Spectrum-sharing studies typically need 5G parameters, such as the spectrum emission mask (SEM); however, no such information is available for the new system to achieve accurate results. The proposed model is suitable for spectrum-sharing studies between 5G and other wireless systems without the need for the 5G SEM. Moreover, the existing model is implemented in a new application (i.e., 5G) in the 28-GHz band with different 5G bandwidths. Furthermore, the FS parameters and its frequency allocation are selected based on the Canadian standards to obtain preliminary results for the co-existence between the 5G system and the FS. Results show that co-existence is feasible when certain distances are applied, especially with higher 5G bandwidths (such as 0.5 and 1 GHz) when the 5G system acts as an interferer. In addition, the antenna position plays a major role in reducing the required separation distances between the victim receiver and the interfering transmitter. This model can be used for any future mobile generation such as the sixth generation (6G) mobile system if its PSD is known. This study is concurrent with the worldwide spectrum-sharing studies requested by the International Telecommunication Union for WRC-19.

HIGH ALTITUDE PLATFORM STATIONS IN DESIGN WIRELESS COMMUNICATION SYSTEM FOR COVER THE SPECIFIC AREA

This paper explains how to design a wireless communication system via high altitude platform stations HAPS to cover the specific area (Using Diwaniyah city area as a model). High altitude platform station HAPS is unmanned airplane provides the wireless communication service to the wider area. It is designed to work at high altitude between (17-22 Km) and coverage area 400 Km. This study illustrated for calculating the co-channel interference between HAPS ground station with a terrestrial station and satellite station. Free space losses for a HAPS ground station has been applied to meet the geographic of Diwaniyah city. In addition, explaining the relationship between elevation angles with the radius of the coverage area. Interference mitigation techniques have been given, such as improving the antenna radiation pattern, then it proposed the elevation angle for the HAPS's ground stations to reduce an interference between HAPS network with Fixed Service (FS) and fixed satellite service (FSS). Finally, this study explains the relationship between elevation angles with the radius of the coverage area. For more reliability, the Scenario for covers the city of Diwaniya. Two ground stations have been proposed to connect with high-altitude platform station.

Coexistence of 5G With the Incumbents in the 28 and 70 GHz Bands

A promising way of realizing the fifth generation (5G) wireless systems is to operate 5G deployments at higher frequency bands, specifically in the millimeter-wave (mmW) spectrum (30-300 GHz). Access to such spectrum bands will enable future 5G wireless systems to meet the 5G requirements of peak rate greater than 10 Gb/s, and cell edge rate of up to 1 Gb/s. However, the emerging 5G systems will need to coexist with a number of incumbent systems in these bands. This paper provides an extensive study of the co-channel coexistence of 5G in two critical mmW bands, 27.5-28.35 GHz (28 GHz) and 71-76 GHz (70 GHz) bands, where fixed satellite service (FSS) and fixed service (FS), such as wireless backhaul, are the predominant incumbent users. In the 28-GHz study, we show that interference from 5G into the FSS space stations can be kept below the FSS interference protection criterion. We also characterize the minimum separation distance between the FSS earth stations (ESs) and 5G in order to protect the 5G system from interference due to the ESs transmissions. In the 70-GHz study, we show that the 5G-to-FS interference could be a potential issue in certain scenarios, but we introduce techniques to significantly suppress this interference, while maintaining acceptable performance of the 5G systems. For each study, we suggest appropriate deployment strategies for a 5G system based on our results.

Numerical Simulation Study for Frequency Sharing Between Micro-Cellular Systems and Fixed Service Systems in Millimeter-Wave Bands

This paper presents numerical simulation results to study the impact of the co-existence between a fixed service (FS) system and 5G small cell networks at 28-, 38-, and 60-GHz millimeter-wave (mmWave) frequency bands. For this paper, two scenarios are considered: aggregation of interference from small cells into an FS receiver from base stations (BSs) to their associated user equipment (UE) (downlink) and the aggregation of cellular interference at the FS receiver from UEs to their associated BSs (downlink). Moreover, mmWave-specific propagation characteristics and attenuation factors are considered for a more precise simulation study. The simulation results determine how much interference rejection is required to protect the operation of FS. In addition, currently available mmWave modular antenna array (MAA) architectures are introduced. Based on the information, additionalmmWave frequency sharing study is performed using the realistic MAA radiation patterns. Last, we compare and analyze the performance differences between ITU standard models and MAA solutions.

Resource Allocation for Cognitive Satellite Communications With Incumbent Terrestrial Networks

The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects satellite communications (SatCom) as well as terrestrial systems. The goal of this paper is to propose resource allocation (RA) techniques, i.e., carrier, power, and bandwidth allocation, for a cognitive spectrum utilization scenario where the satellite system aims at exploiting the spectrum allocated to terrestrial networks as the incumbent users without imposing harmful interference to them. In particular, we focus on the microwave frequency bands 17.7–19.7 GHz for the cognitive satellite downlink and 27.5–29.5 GHz for the cognitive satellite uplink, although the proposed techniques can be easily extended to other bands. In the first case, assuming that the satellite terminals are equipped with multiple low block noise converters (LNB), we propose a joint beamforming and carrier allocation scheme to enable cognitive space-to-Earth communications in the shared spectrum where fixed service (FS) microwave links have priority of operation. In the second case, however, the cognitive satellite uplink should not cause harmful interference to the incumbent FS system. For the latter, we propose a joint power and carrier allocation (JPCA) strategy followed by a bandwidth allocation scheme, which guarantees protection of the terrestrial FS system while maximizing the satellite total throughput. The proposed cognitive satellite exploitation techniques are validated with numerical simulations considering realistic system parameters. It is shown that the proposed cognitive exploitation framework represents a promising approach for enhancing the throughput of conventional satellite systems.

Design of Wireless Communication System to Cover Specific Area by Using HAPS

This paper is meeting the principles of how to design coverage area for Sulaymaniyah city, using a new technology, which named HAPS. It started with small introduction for HAPS with its advantages, compare it with terrestrial and satellite systems, and specify requirements for design. Such as, specify the center of coverage area to find the coordinates. Then, supposed the coverage area for the city, elevation angle, and the location of earth stations which will connect HAPS with other networks and reduce the Interference with Fixed Services (FS) and Fixed Satellite Services (FSS).Mitigation technique of interference is given. Also, path loss and fading loss has been applied to meet the geographic of Sulaymaniyah city.

Spectrum Sharing Model for Coexistence between High Altitude Platform System and Fixed Services at 5.8 GHz

This paper sheds the light on coexistence and sharing between high altitude platform system (HAPS) and Fixed Services (FS) as a recently critical issue due to the spectrum shortage. International Telecommunications Union Radiocommunications sector (ITU-R) allocated the 5850-7075 MHz band for the operation of HAPS along with existing FS services. Therefore, coexistence and sharing requirements like separation distance and frequency separation coordination must be achieved in terms of both co-channel and adjacent channel frequencies. The interference analysis mode based on the spectrum emission mask (SEM) is applied in the mentioned band to extract the required frequency separation to protect adjacent channel interference. Also interference to noise ratio (INR) as standard interference criteria is utilized.

저궤도 위성망과 FS 시스템의 주파수 공유 방안 연구

본 논문에서는 저궤도 위성망(LEO satellite network)과 FS 시스템(Fixed Service system) 동일한 하향 링크 주파수를 사용하는 통신 환경에서 두 시스템이 간섭 영향 없이 운용될 수 있는 방안을 연구하였다. 저궤도 위성망에 의한 FS 시스템으로의 간섭 시나리오의 경우 동시에 운용되는 저궤도 위성 빔의 수에 따라 FS 시스템의 영역을 정의하여 각 영역에서의 간섭 영향을 분석하였다. 또한 FS 시스템에 의한 지구국으로의 간섭 시나리오에서는 지구국의 보호 영역을 정의하여 보호 영역의 반경에 따른 간섭 영향을 분석하였다. 분석한 결과는 두 스템이 간섭 영향 없이 운용될 수 있는 공유 조건으로 FS 시스템의 설계 단계에 활용될 수 있다. This paper addresses the analysis of the interference produced between the LEO(Low Earth Orbit) satellite constellation and FS(Fixed Service) system operating in the same frequency and area. At first, we calculates the interference of FS system from the LEO satellite constellation depending on the number of LEO satellite antenna beams. Simulation results show that the amount of interference that was calculated from each region. This result can be used to define the carrier level for protecting FS system from total interference by LEO satellite constellation. In the second scenario, we calculates the interference of LEO satellite system earth station by the FS link depending on radius of protection area. The presented results can be used to design FS systems minimizing interference to earth station.

An Evaluation of Interference Mitigation Schemes for HAPS Systems

The International Telecommunication Union-Radiocommunication sector (ITU-R) has conducted frequency sharing studies between fixed services (FSs) using a high altitude platform station (HAPS) and fixed-satellite services (FSSs). In particular, ITU-R has investigated the power limitations related to HAPS user terminals (HUTs) to facilitate frequency sharing with space station receivers. To reduce the level of interference from the HUTs that can harm a geostationary earth orbit (GEO) satellite receiver in a space station, previous studies have taken two approaches: frequency sharing using a separated distance (FSSD) and frequency sharing using power control (FSPC). In this paper, various performance evaluation results of interference mitigation schemes are presented. The results include performance evaluations using a new interference mitigation approach as well as conventional approaches. An adaptive beamforming scheme (ABS) is introduced as a new scheme for efficient frequency sharing, and the interference mitigation effect on the ABS is examined considering pointing mismatch errors. The results confirm that the application of ABS enables frequency sharing between two systems with a smaller power reduction of HUTs in a cocoverage area compared to this reduction when conventional schemes are utilized. In addition, the analysis results provide the proper amount of modification at the transmitting power level of the HUT required for the suitable frequency sharing.

Protection of FS receivers from the interference produced by HEO FSS satellites in the 18 GHz band: Effect of the roll‐off characteristics of the HEO system satellite antenna beams

AbstractThis paper focuses on the protection of fixed service (FS) receivers from the aggregate interference produced by the satellites of multiple highly elliptical orbit satellite systems (HEOs). It analyzes the protection given to FS receivers operating in the 18 GHz frequency band by the power flux‐density (pfd) mask contained in Article 21 of the 2003 edition of the Radio Regulations [International Telecommunication Union, 2003.]. This mask establishes the maximum allowable value for the pfd produced by any of the satellites of a non‐geostationary system at the Earth's surface. The protection offered to FS receivers by this mask is analyzed in four interfering environments, each containing three identical HEO systems. Four types of HEO systems, with different orbital characteristics, are considered: three having satellites that operate only in the northern hemisphere and one having satellites that operate in both hemispheres. All satellite antennas are assumed to radiate 0.3° spot beams. Each HEO satellite is modelled so that the maximum pfd it produces at the Earth's surface just meets the RR Article 21 mask and the analysis takes into account the roll‐off characteristics of the satellite antenna beams. To reflect the multiplicity of possibilities concerning the geographical location and technical characteristics of the victim FS receiver (e.g. latitude, longitude, azimuth and elevation of its receiving antenna, antenna gain, receiver noise temperature, etc.) a number of cases were evaluated. The concept of interference in excess [Int. J. Satellite Commun. Networking 2006; 24: 73–95] was used to combine the results corresponding to FS receivers located at the same latitude and having the same receiving antenna elevation angle but for which the location longitude and the azimuth of the pointing direction of its receiving antenna are randomly chosen. Results are expressed in terms of the cumulative distribution function of the interference in excess. Copyright © 2008 John Wiley & Sons, Ltd.

Estimação da Localização, Potência e Direção de Radiação de Transmissores do Serviço Fixo Terrestre a Partir de Medidas Feitas por Satélite Não-Geoestacionário

Satellites of a non-geostationary communication system may be victims of harmful interference produced by terrestrial fixed service (FS) transmitting stations operating in the same frequency band. It is important to the satellite system operator to identify the specific areas on Earth’s surface containing the FS stations that are responsible for such interference. This would be a first step for solving the problem via bilateral coordination with each of the involved FS operators. This work presents a mathematical model for the problem and proposes that the identification of these areas be made though the estimation of the transmitted power and the antenna pointing (azimuth and elevation angles) of the various FS stations, based on received power measurements taken on the beams of a test non-GSO satellite. This work also investigates the particular aspects of the problem and proposes the Extended Kalman Filter (EKF) as the algorithm for estimation.

The coexistence of OFDM-based systems beyond 3G with fixed service microwave systems

In this paper, we study the coexistence of orthogonal frequency division multiplexing (OFDM)-based systems beyond 3G (B3G) and point-to-point (P-P) fixed service (FS) microwave systems. The advanced general analytical model derived via a power spectral density (PSD) analysis proposed in this paper has two advantages in comparison with the conventional minimum coupling loss (MCL) method. First, the interfering signal power that appears in the band of a victim system can be easily assessed without a spectrum emission mask. Second, when transmit power is not allocated to some subcarriers overlapping the band of the victim system in order to mitigate B3G OFDM-based systems interference with other systems, the general analytical model can successfully assess the interference from the B3G systems into FS systems, whereas the MCL method incorporating the spectrum emission mask cannot be applied in the presence of the same interference condition. The proposed model can be derived in a closed form and is simply implemented with the help of simulation, and thus the solution can be obtained in significantly reduced time. Through application of the proposed model, coexistence results are analyzed in a co-channel and adjacent channel with respect to guard band and minimum separation distance.

On the power flux-density limits to protect the fixed service from HEO FSS satellites emissions in the 18 GHz band

This paper focuses on the protection of Fixed Service (FS) receivers from the aggregate interference produced by the satellites of multiple highly elliptical orbit satellite systems (HEOs). It analyzes the protection given to FS receivers operating in the 18 GHz frequency band by different power flux-density (pfd) masks. These masks establish the maximum allowable pfd produced by each HEO satellite at the Earth's surface. The protections offered by four different pfd masks are analysed in two interfering environments, each containing three HEO systems. Two types of HEO system, with different orbital characteristics, are considered: one having satellites that operate only in the northern hemisphere and another having satellites that operate in both hemispheres. To reflect the multiplicity of possibilities concerning the geographical location and technical characteristics of the victim FS receiver (e.g. latitude, longitude, azimuth and elevation of its receiving antenna, antenna gain, receiver noise temperature, etc.) a large amount of results and curves is usually generated by the studies, making it difficult to draw general conclusions on the protection offered by the pfd masks under analysis. In looking for alternative ways of presenting the obtained results, a new variable was defined: the interference in excess. This new variable was defined in a way so that its probability distribution function reflects the protection given to an FS receiver located at a given latitude with a given receiving antenna elevation angle. It indicates the protection of an FS receiver for which the location longitude and the azimuth of the pointing direction of its receiving antenna are randomly chosen. This allows the large amount of results to be compacted into a small number of more representative curves from which general conclusions on the protection offered by the different pfd masks are easily drawn. Copyright © 2006 John Wiley & Sons, Ltd.

Application of a new methodology for the coordination of the fixed service (FS) with mobile earth stations on board vessels in realistic interference conditions

This paper addresses an in-depth analysis of the interference produced to the fixed service (FS) by the earth stations on board vessels (ESVs) operating with geostationary satellites and proposes a new methodology for the development of coordination areas around the FS receivers, taking into account parameters such as the velocity of the ESVs and their frequency of passage from specific locations. Simulations performed in realistic interference conditions prove the validity of the new methodology, which can constitute the basis for the development of new methods for the coordination between the fixed service and the ESVs contributing, by this way, significantly to the harmonic coexistence of the two services.

A new methodology for the determination of the co-ordination area around stations of the fixed service (FS) with respect to mobile Earth stations on board vessels (ESVs)

The extensive use of Earth stations located on board sea going vessels (ESVs) has created the necessity for the development of a new type of co-ordination area around the fixed service receivers (FSRs) operating in frequency bands C and Ku. To date there is not a single method concerning the calculation of the co-ordination area around the FSRs, which takes into account the mobility of the interfering stations. This paper addresses an in-depth analysis of the interference produced to the FSRs by the ESVs and proposes a new method for the development of the co-ordination area around the FSRs, taking into account parameters such as the velocity of the ESVs and their frequencies of passage from specific locations. Simulations performed for three different operational scenarios prove the validity of the new methodology. Copyright © 2005 John Wiley & Sons, Ltd.