Spatial Characteristics of Distortion Radiated from Antenna Arrays with Transceiver Nonlinearities

The distortion from massive MIMO (multiple-input--multiple-output) base stations with nonlinear amplifiers is studied and its radiation pattern is derived. The distortion is analyzed both in-band and out-of-band. By using an orthogonal Hermite representation of the amplified signal, the spatial cross-correlation matrix of the nonlinear distortion is obtained. It shows that, if the input signal to the amplifiers has a dominant beam, the distortion is beamformed in the same way as that beam. When there are multiple beams without any one being dominant, it is shown that the distortion is practically isotropic. The derived theory is useful to predict how the nonlinear distortion will behave, to analyze the out-of-band radiation, to do reciprocity calibration, and to schedule users in the frequency plane to minimize the effect of in-band distortion

Adaptive multibeam phased array design for a Spacelab experiment

The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio

Project apollo. ship-shore communications using radio satellite relay

Requirements for antennas, radio and terminal equipment aboard Apollo communication and tracking ships to communicate with land stations by satellite rela

Programmable rate modem utilizing digital signal processing techniques

The engineering development study to follow was written to address the need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) modulation. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. Here design tradeoffs in each portion of the modulator and demodulator subsystem are outlined, and viable circuit approaches which are easily repeatable, have low implementation losses and have low production costs are identified. The research involved for this study was divided into nine technical papers, each addressing a significant region of concern in a variable rate modem design. Trivial portions and basic support logic designs surrounding the nine major modem blocks were omitted. In brief, the nine topic areas were: (1) Transmit Data Filtering; (2) Transmit Clock Generation; (3) Carrier Synthesizer; (4) Receive AGC; (5) Receive Data Filtering; (6) RF Oscillator Phase Noise; (7) Receive Carrier Selectivity; (8) Carrier Recovery; and (9) Timing Recovery

NASA Unmanned Aircraft (UA) Control and Non-Payload Communication (CNPC) System Waveform Trade Studies

Unmanned Aircraft Systems (UAS) represent a new capability that will provide a variety of services in the government (public) and commercial (civil) aviation sectors. The growth of this potential industry has not yet been realized due to the lack of a common understanding of what is required to safely operate UAS in the National Airspace System (NAS). To address this deficiency, NASA has established a project called UAS Integration in the NAS (UAS in the NAS), under the Integrated Systems Research Program (ISRP) of the Aeronautics Research Mission Directorate (ARMD). This project provides an opportunity to transition concepts, technology, algorithms, and knowledge to the Federal Aviation Administration (FAA) and other stakeholders to help them define the requirements, regulations, and issues for routine UAS access to the NAS. The safe, routine, and efficient integration of UAS into the NAS requires new radio frequency (RF) spectrum allocations and a new data communications system which is both secure and scalable with increasing UAS traffic without adversely impacting the Air Traffic Control (ATC) communication system. These data communications, referred to as Control and Non-Payload Communications (CNPC), whose purpose is to exchange information between the unmanned aircraft and the ground control station to ensure safe, reliable, and effective unmanned aircraft flight operation. A Communications Subproject within the UAS in the NAS Project has been established to address issues related to CNPC development, certification and fielding. The focus of the Communications Subproject is on validating and allocating new RF spectrum and data link communications to enable civil UAS integration into the NAS. The goal is to validate secure, robust data links within the allocated frequency spectrum for UAS. A vision, architectural concepts, and seed requirements for the future commercial UAS CNPC system have been developed by RTCA Special Committee 203 (SC-203) in the process of determining formal recommendations to the FAA in its role provided for under the Federal Advisory Committee Act. NASA intends to conduct its research and development in keeping with this vision and associated architectural concepts. The prototype communication systems developed and tested by NASA will be used to validate and update the initial SC-203 requirements in order to provide a foundation for SC-203's Minimum Aviation System Performance Standards (MASPS)

Multi-band OFDM UWB receiver with narrowband interference suppression

A multi band orthogonal frequency division multiplexing (MB-OFDM) compatible ultra wideband (UWB) receiver with narrowband interference (NBI) suppression capability is presented. The average transmit power of UWB system is limited to -41.3 dBm/MHz in order to not interfere existing narrowband systems. Moreover, it must operate even in the presence of unintentional radiation of FCC Class-B compatible devices. If this unintentional radiation resides in the UWB band, it can jam the communication. Since removing the interference in digital domain requires higher dynamic range of analog front-end than removing it in analog domain, a programmable analog notch filter is used to relax the receiver requirements in the presence of NBI. The baseband filter is placed before the variable gain amplifier (VGA) in order to reduce the signal swing at the VGA input. The frequency hopping period of MB-OFDM puts a lower limit on the settling time of the filter, which is inverse proportional to notch bandwidth. However, notch bandwidth should be low enough not to attenuate the adjacent OFDM tones. Since these requirements are contradictory, optimization is needed to maximize overall performance. Two different NBI suppression schemes are tested. In the first scheme, the notch filter is operating for all sub-bands. In the second scheme, the notch filter is turned on during the sub-band affected by NBI. Simulation results indicate that the UWB system with the first and the second suppression schemes can handle up to 6 dB and 14 dB more NBI power, respectively. The results of this work are not limited to MB-OFDM UWB system, and can be applied to other frequency hopping systems

Communication satellite systems for Alaska

Technical and cost factors for implementation of Alaskan communication satellite syste

mmWave RX interference test considerations and challenges in OTA environment

Abstract. Verifying equipment using the OTA (Over the Air) techniques is a recent addition in telecommunication testing. With the addition of new frequency bands, mmWave (millimetre wave) technology and massive MIMO (Multiple-Input-Multiple-Output), the 3GPP (3rd Generation Partnership Programme) has cemented OTA testing as the focus for verifying future equipment. However, these verifying methods are still in development, or stated as general ideas of how they are meant to be done. The main goal of this thesis is to study and design a system for receiver radio testing, according to 3GPP specifications. The test system must operate in mmWave frequency range and must be integrated to a pre-built antenna testing environment. The motivation is to verify the testing method proposed by 3GPP for mmWave receiver testing and analyse it thoroughly. This thesis aims to answer such research questions as: Is the testing method proposed by 3GPP valid for verifying mmWave frequency products? What are the major challenges, when designing test setup for high frequency devices? How can the method be improved and how it can be applied in the future? This thesis answers the first question by applying the proposed test methods in practical scenario and testing an actual eNB/gNB (eNodeB / Next generation eNodeB). Since the proposed test method has only general outline of what equipment to use, the actual test scenario will have additional pieces of testing equipment. For the second question, this thesis discusses the theory behind 5G and mmWave challenges, and how the use of these techniques is justified for practical usage. This theory is based on former research as well as current specifications applied by the 3GPP. The third research question is part of the final analysis, where the test results are analysed, and the major parts are discussed in depth. These discussions are then further expanded on with the purpose of suggesting possible areas of improvement as well as how to apply these findings into future use. The final outcome of the study is that the suggested test method is workings as it was presented by the 3GPP. However, there are some areas of improvement that should be discussed as a future work.Millimetriaaltojen RX interferenssi RF-testit OTA-ympäristössä. Tiivistelmä. Tuotteiden testaaminen ilmateitse on melko uusi lisäys tietoliikennetestauksen tekniikoihin, joita käytetään tuotteiden varmentamiseen. 3GPP on osoittanut OTA-testauksen keskeiseksi osaksi tulevien tuotteiden verifiointia. Osaksi tämä johtuu uusien taajuuskanavien käyttöönotosta, millimetriaaltoteknologiasta sekä massive MIMO tuotteiden yleistymisestä. Vaikka testaustapoja on jo ehdotettu, ne ovat vielä mahdollisesti vain yleisiä ideoita kuinka testejä tulisi suorittaa. Työn tarkoituksena on tutkia ja suunnitella vastaanottimen testaamiseen tehty testijärjestely. Testijärjestelyn tulee toimia millimetriaalloille tarkoitetulla taajuusalueella, ja työ tulee integroida valmiiksi suunniteltuun CATR-antennikammioon. Työn motivaationa on verifioida 3GPP:n ehdottama testausmetodi, millimetriaaltotaajuuksilla toimivien vastaanottimien toimivuus ja analysoida tämä tarkemmin. Tämä työ pyrkii vastaamaan tutkimuskysymyksiin kuten: Onko 3GPP:n ehdottama testimetodi pätevä verifioimaan millimetriaaltotaajuuksilla toimivia tuotteita? Mitä ovat suurimmat haasteet, kun suunnitellaan testijärjestelyä korkeataajuuksisille laitteille? Kuinka tätä metodia voidaan parantaa, ja kuinka sitä voidaan hyödyntää tulevaisuudessa? Työ vastaa ensimmäiseen tutkimuskysymykseen ottamalla käyttöön 3GPP:n ehdottamat testausmetodit käytännön testijärjestelyssä, ja testaamalla näillä metodeilla oikean tuotteen. Tällä tavoin ehdotettu testausmetodi pyritään verifioimaan. Tulee kuitenkin ottaa huomion, että ehdotetussa metodissa esitetään vain yleisellä tasolla mitä testaamiseen käytettävää laitteistoa käytetään. Tämän takia testeissä tulee olemaan joitain lisälaitteita, jotka ovat kuitenkin osa kokonaista testiympäristöä. Toiseen tutkimuskysymykseen perehdytään käymällä läpi teoriaa 5G:n ja millimetriaaltoteknologian haasteista, ja kuinka näitä tekniikoita tullaan hyödyntämään tulevaisuudessa. Teoria perustuu aiempaan tutkimukseen, sekä nykyisiin spesifikaatioihin jota 3GPP on kehittänyt. Kolmas tutkimuskysymys on osa lopullista analyysiä, jossa testien tulokset analysoidaan ja niiden pääkohdista keskustellaan tarkemmin. Tämän jälkeen keskusteluja täsmennetään liittyen mahdollisiin parannuksiin tietyllä aihealueilla, sekä mahdollisuuksista käyttää kyseisiä tuloksia tulevaisuudessa. Lopullinen päätelmä on, että ehdotettu testausmetodi toimii kuten se oli esitetty 3GPP:n dokumentoinnissa. On kuitenkin joitain osa-alueita, joita voitaisiin käsitellä tarkemmin tai jopa parantaa tulevaisuutta varten