72 research outputs found
Design and experimental evaluation of a low-complexity spatial combiner for LTE distributed antenna systems
A self-organized metaheuristic approach towards inter-cell interference management for LTE-Advanced
Radio channel modelling for 5G telecommunication system evaluation and over the air testing
Abstract
This thesis discusses radio channel modelling for evolving radio access and of using the models in practice in a setup for radiated testing of radio devices. New telecommunication systems are constantly being developed to address continuously increasing wireless communication needs. The first pieces of intensively developed fifth generation (5G) networks and devices are planned to be available, in some form, approximately by 2020. An interesting feature of 5G concerning propagation and consequently channel modelling, is the expected utilization of frequencies clearly higher than the legacy cellular systems.
This work aims to define a channel model for the simulated evaluation of the coming 5G systems. New requirements for the channel model are identified and addressed. Further, over the air (OTA) testing of 5G devices in fading conditions is examined and a new setup is proposed. The test environment aims to reconstruct a time variant electromagnetic (EM) field around a device under test (DUT) considering the spatial, polarimetric, Doppler, and delay dispersion characteristics specified by the target channel model. Components and key design parameters of the setup are designated.
It was found that the proposed map-based channel model is capable of fulfilling the identified requirements. Furthermore, the simulations indicate that the state-of-the-art geometry-based stochastic channel model (GSCM) may give over-optimistic multi-user MIMO (MU-MIMO) performance in an urban micro-cellular environment. The sectored OTA concept was shown appropriate for device testing. Key parameters, such as the physical dimensions of the multi-probe anechoic chamber (MPAC) OTA configuration and the number of active probes, were determined by simulations.
The 3GPP is the main forum working towards 5G standards. A channel model for 5G evaluations has recently (2016) been specified. The base-line model is a GSCM inherited from the 4G models. However, the author expects that the proposed map-based models will gain popularity in the future, despite the current widespread use of GSCMs. In the 3GPP working group RAN4 (Radio performance and protocol aspects) the test methods for 5G user equipment (UE) are currently (2017) under investigation. The proposed sectored MPAC method has been contributed to and is under consideration in 3GPP. Even if it is not approved for UE testing, the author expects it to be useful for performance testing of base stations (BSs).Tiivistelmä
Tämän väitöskirjan sisältönä on radiokanavamallinnus langattomia tiedonsiirtojärjestelmiä varten ja lisäksi mallien käyttöönottoa tulevien radiolaitteiden säteilevässä testauksessa. Uusia tietoliikennejärjestelmiä kehitetään jatkuvasti, yhtä lailla jatkuvasti kasvavien tiedonsiirtotarpeiden tyydyttämiseksi. Ensimmäisten verkkojen ja päätelaitteiden pitäisi olla saatavilla tulevaan viidennen sukupolven (5G) järjestelmään vuoden 2020 tietämillä.
Työn tarkoituksena on määritellä kanavamalli 5G-järjestelmän simulointeja varten ja sitä edeltäen tunnistaa kanavamallin vaatimukset. Lisäksi tutkimuksen aiheena on 5G-laitteiden säteilevä (OTA) testaus häipyvässä radiokanavassa ja uuden testijärjestelmän määrittely tätä tarkoitusta varten. Ehdotetun testijärjestelmän keskeisenä toimintona on halutun sähkömagneettisen (EM) kentän tuottaminen testattavan laitteen ympärille. EM-kentän pitää olla kanavamallin mukainen ja toteuttaa sen häipymä-, tila-, polarisaatio-, doppler- ja viiveominaisuudet. Testijärjestelmän komponentit ja tärkeimmän suunnitteluparametrit pyritään selvittämään tässä työssä.
Tutkimuksessa havaittiin, että ehdotettu karttapohjainen kanavamalli toteuttaa 5G-mallille asetetut vaatimukset. Simuloinnit osoittavat myös, että tyypillisessä kaupunkiympäristössä suosittu GSCM-malli yliarvioi kanavan kapasiteetin monen käyttäjän MIMO-tekniikka käytettäessä. Lisäksi osoitettiin sektoroidun OTA-järjestelmän, jossa hyödynnetään useita antenneja, radiokanavaemulaattoria sekä radiokaiutonta huonetta (MPAC), käyttökelpoisuus 5G-laitteiden testaukseen. Kyseisen testausjärjestelmän parametrit määriteltiin.
3GPP on tärkein foorumi, jolla 5G-standardeja luodaan. Siellä on hiljattain (2016) sovittu 5G-simulointeja varten kanavamalli, joka ei ole tässä työssä ehdotetun kaltainen. Standardoitu malli on tyypiltään GSCM ja se on johdettu suoraan edellisen sukupolven (4G) kanavamallista. Kirjoittaja olettaa tästä GSCM:n nykyisestä vahvasta asemasta huolimatta, että ehdotettu karttapohjainen kanavamalli lisää suosiotaan tulevaisuudessa. Parhaillaan (2017) on 3GPP:n RAN4-työryhmässä käynnissä 5G-päätelaitteiden (UE) testimenetelmien määrittelyvaihe. Väitöskirjassa tutkittua sektoroitua MPAC-menetelmää on ehdotettu työryhmälle standardoitavaksi. Vaikka mainittua menetelmää ei siellä standardoitaisikaan UE-testaukseen, niin voidaan olettaa menetelmän olevan hyödyllinen erityisesti tukiasemien säteilevään testaukseen
Correlation of hybrid beamforming arrays in the context of OTA testing
Abstract
Hybrid beamforming antenna arrays are a prominent component in communications at mm-wave frequencies. Multiple analogue beamforming arrays will be used for spatial multiplexing of signals also in hand held devices. In this work we derive the correlation coefficient for signals received by two ideal arrays in simple power angular distribution schemes. The purpose is to develop tools for evaluating over-the-air setups for testing of hybrid beamforming devices. We show a few exemplary correlation error evaluations that compare near field multi-probe OTA setups with a perfect target channel model. Results indicate that the correlation error increases with decreasing range length and channel angular spread. Moreover, larger inter-array spacing and sub-array sizes increase the correlation error
Fading channel emulation for massive MIMO testing using a conductive phase matrix setup
Abstract
Functionalities, algorithms, and performances of massive MIMO base stations should be tested in versatile fading radio channel conditions. Base stations of 5G “New radio” that operate on sub 6 GHz frequency bands typically provide antenna connectors enabling RF cable connection of test devices to the device under test (DUT). Furthermore, the number of DUT antennas is high and consequently the need of fading channel emulator (CE) resources becomes high. An approach can be taken to reduce the number of independent fading channels to be emulated. This can be done by using a phase shifting and combining unit (aka phase matrix unit) in between the DUT and CE. The phase matrix concept in fading emulation, together with its capabilities and limitations, is discussed in this paper
Unified low‐layer power allocation and high‐layer mode control for video delivery in device‐to‐device network with multi‐antenna relays
Sympathetic current oscillations at an enzyme electrode induced by potential oscillations at a Pt surface
A dual-electrode set-up is introduced in order to demonstrate that electrochemical oscillations at one electrode can induce sympathetic oscillations at the other electrode. A pure Pt surface is used as a primary electrode at which the potential oscillations of the [Fe(CN)6]3- system with convective feedback occur and stimulate current oscillations at a Pt or glucose oxidase enzyme (GOD) + tetraethyl silicate (TEOS) coated electrode placed in the vicinity. The current density of the primary electrode and glucose concentration can be used to influence the frequency and amplitude of oscillations at the GOD + TEOS electrode. Keywords: Oscillations, Glucose oxidase, Ferricyanid
Assessing measurement distances for OTA testing of massive MIMO base station at 28 GHz
AbstractThis paper discusses physical dimensions for a multi probe anechoic chamber based (MPAC) over-the-air (OTA) setup aiming for base station (BS) testing. The target frequency of the simulated massive multiple-input-multiple-output (MIMO) BS arrays is 28 GHz. The assessment is performed with two metrics. The first metric is a new power metric based on assumptions of a code book of fixed beams and planar waves. The second one is the multi-user (MU) MIMO sum rate capacity. The intention is to evaluate physical dimensions in metres with respect to different BS array sizes. Simulation results indicate that OTA performance of a BS array with maximum dimension of 0.15m could be measured with a setup having measurement distance of approximately 1m
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