Spectrum Sensing of DVB-T2 Signals in Multipath Channels for Cognitive Radio Networks

© 2018 VDE VERLAG GMBHIn this paper, spectrum sensing of digital video broadcasting-second generation terrestrial (DVB-T2) signals in different fading environments with energy detection (ED) is considered. ED is known to achieve an increased performance among low computational complexity detectors, but it is susceptible to noise uncertainty. By taking into consideration the edge pilot and scattered pilot periodicity in DVB-T2 signals, a low computational complex noise power estimator is proposed. It is shown analytically that the choice of detector depends on the environment, the detector requirements, the available prior knowledge and with the noise power estimator. Simulation confirm that with the noise power estimator, ED significantly outperforms the pilot correlation-based detectors. Simulation also show that the proposed scheme enables ED to obtain increased detection performance in fading channels

Cell measurement in 5g unlicensed spectrum

Abstract. The objective of the thesis is to implement a firmware for cell measurement in an unlicensed spectrum. As a part of the thesis, theory for downlink physical layer and resources are reported as they are related to the implementation. Also, a short introduction to New radio cell measurement in licensed and unlicensed spectrum are presented and the main differences between those radio access technologies are shown. The biggest differences, but also the most challenging parts between licensed and unlicensed spectrum measurements are Listen-before-talk and expanded quasi co-location assumption. Listen-before-talk is used to evaluate the state of the channel and expanding quasi co-location assumption to all synchronization blocks to make time shift possible for the block. The performance of the implementation was measured in two different ways. The first way was to track a data and a program memory usage behave. The second way was to measure a cycle usage to see how central processing unit load behave in comparison to New radio. The results show clearly that the data memory usage increases linearly as a function of the candidate locations. Also, the program memory size increases about 5%. The results of the program memory show that the implementation reuses a lot of the New radio code as this new access technology does not increase the size of the program memory much. This kind of the results can also be seen with the cycle usage measurements. When it was measured only one candidate location in the unlicensed spectrum, the cycle usage increases about 10% when comparing to the New radio. However, the cycle usage did not increase linearly when more candidate location was measured. It was observed that the more candidate locations were measured, the less one candidate location measurement consumes the cycles on average. The observation supports the conclusion that the implementation reuses a lot of New radio code and there is a lot of the common code.Solumittaus lisensoimattomilla 5G-taajuuksilla. Tiivistelmä. Tavoite opinnäytetyölle on toteuttaa laiteohjelmisto, joka suorittaa solumittausta lisensoimattomilla 5G-taajuuksilla. Osana opinnäytetyötä on esitetty teoriaa siltä osin kuin se on toteutuksen kannalta olennaista. Teoria käsittelee 5G-yhteyden alalinkin fyysisen kerroksen eri osia ja resursseja sekä solumittausta lisensoidulla ja lisensoimattomilla 5G-taajuuksilla kuin myös niiden eroja solumittauksessa. Suurimmat erot lisensoidulla ja lisensoimattomilla 5G-taajuuksien solumittauksissa, ja samalla myös pääasiallinen haaste syntyi kuuntele ennen puhetta -teknologiasta sekä näennäisen yhteissijoittamisen käsitteen laajentamisesta. Kuuntele ennen puhetta -teknologiaa käytetään kanavan tilan seurantaan. Näennäisen yhteissijoittamisen käsiteen laajentaminen mahdollistaa synkronisointi lohkon siirtämisen aikatasolla suhteessa muihin synkronisointi lohkoihin. Toteutuksen suoritustasoa mitataan kahdella eri tavalla. Ensimmäinen tapa on seurata muistin käyttäytymistä solumittauksessa sekä toteutuksesta syntyvää ohjelmistomuistin kasvua. Toinen tapa seurata suorituskykyä on mitata syklejä. Syklejä mittaamalla saadaan tietää kuinka paljon prosessori kuormittuu mittausten aikana. Tulokset osoittavat, että muistin kulutus solumittauksessa kasvaa lineaarisesti ehdokaspaikkojen funktiona. Myös ohjelmistomuistin koko kasvaa noin 5%. Ohjelmistomuistin kasvusta voidaan päätellä, että laiteohjelmisto uudelleenkäyttää paljon vanhaa lisensoidun taajuuden mittausohjelmistoa, jolloin uuden radiopääsytekniikan toteutus ei juurikaan nosta ohjelmiston kokoa. Saman kaltaisia tuloksia voidaa myös huomata syklien mittauksessa. Kun mitattiin yhden lisensoimattoman taajuuden ehdokaspaikan mittauksesta aiheutuvaa syklien kulutusta, huomattiin sen nousevan 10% verrattuna vastaavaan lisensoidun taajuuden mittaukseen. Kuitenkin, kun suoritettiin useamman ehdokaspaikan solumittaus, huomattiin, että syklimäärä itseasiassa laski per ehdospaikan mittaus. Tästä voidaan päätellä, että kaikki syklit eivät kertaudu jokaisessa ehdokaspaikan mittauksessa, vaan ohjelmisto sisältää paljon niin sanottua yleistä ohjelmistoa. Mitä enemmän ehdospaikkoja on mitattavana, sitä vähemmän yksi mittauspaikka maksaa

Spectrum Sensing of DVB-T2 Signals using a Low Computational Noise Power Estimation

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted ncomponent of this work in other works.Cognitive radio is a promising technology that answers the spectrum scarcity problem arising from the proliferation of wireless networks and mobile services. In this paper, spectrum sensing of digital video broadcasting-second generation terrestrial (DVB-T2) signals in AWGN, WRAN and COST207 multipath fading environment are considered. ED is known to achieve an increased performance among low computational complexity detectors, but it is susceptible to noise uncertainty. Taking into consideration the edge pilot and scattered pilot periodicity in DVB-T2 signals, a low computational noise power estimator is proposed. Analytical forms for the detector are derived. Simulation results show that with the noise power estimator, ED significantly outperforms the pilot correlation-based detectors. Simulation also show that the proposed scheme enables ED to obtain increased detection performance in multi-path fading environments. Moreover, based on this algorithm a practical sensing scheme for cognitive radio networks is proposed.Peer reviewedFinal Accepted Versio

Emerging Prototyping Activities in Joint Radar-Communications

The previous chapters have discussed the canvas of joint radar-communications (JRC), highlighting the key approaches of radar-centric, communications-centric and dual-function radar-communications systems. Several signal processing and related aspects enabling these approaches including waveform design, resource allocation, privacy and security, and intelligent surfaces have been elaborated in detail. These topics offer comprehensive theoretical guarantees and algorithms. However, they are largely based on theoretical models. A hardware validation of these techniques would lend credence to the results while enabling their embrace by industry. To this end, this chapter presents some of the prototyping initiatives that address some salient aspects of JRC. We describe some existing prototypes to highlight the challenges in design and performance of JRC. We conclude by presenting some avenues that require prototyping support in the future.Comment: Book chapter, 54 pages, 13 figures, 10 table

Implementação de redes 5G baseadas em código aberto

Recently, a growth of mobile networks, from a huge connection of only a few devices, to the need for constant maintenance with support even with different technological needs. This requires increasing the capacity of networks to respond to user needs, increasing connection speeds and decreasing latencies. In many cases, the demand for the capabilities offered by the new generation of mobile networks, 5G, remains unanswered with conventional structures, especially in urban areas. As a viable option for these needs, the use of small cells emerged. The use of this equipment is facilitated due to the flexibility offered by the architecture of 5G mobile networks that facilitate the division of the same into functional units with a virtual implementation, thus helping to spread the coverage area. The growing interest in 5G mobile networks and the immense possibilities they offer have given rise to projects focused on the development of 5G mobile networks that are made available for consultation and use by the interested community. These networks are mostly implemented in a virtual way, with the exception of the component responsible for the emission of the radio signal, where some options will be presented for this purpose during the course of the dissertation. As a target of study and evaluation of the state of development and usefulness throughout this dissertation, OpenAirInterface was chosen from among these open-source projects. The complete implementation of the same is presented and described, as well as the tests carried out in order to determine which are the functional bandwidths and which are the options for optimizing its operation. To conclude the work carried out, the results and balance of these tests are presented in the form of speed and latency tests in various bandwidths, verification of occupancy of the same, flexibility in modifying the emission frequency, as well as the result of a test of connecting elements of mobile networks developed by different open-source projects as a way of evaluating the flexibility of these networks.Recentemente temos assistido a um crescimento enorme de redes móveis, desde a conexão de apenas alguns dispositivos, até à necessidade de manter ligação constante com múltiplos equipamentos com necessidades tecnológicas diferentes. Isto requer o aumento da capacidade das redes para dar resposta às necessidades dos utilizadores, aumentar velocidades de conexão e diminuir latências. Em muitos casos, a procura pelas capacidades oferecidas pela nova geração de redes móveis, o 5G, continua sem resposta com as estruturas convencionais, especialmente em áreas urbanas. Como opção viável para essas necessidades, surgiu o uso de small cells. O uso desse equipamento é facilitado devido à flexibilidade oferecida pela arquitetura de redes móveis 5G que facilitam a divisão da mesma em unidades funcionais com uma implementação virtual ajudando assim à propagação da área de cobertura. O interesse crescente de redes móveis 5G e as imensas possibilidades que as mesmas oferecem, fizeram surgir projetos focados no desenvolvimento de redes móveis 5G que são colocados disponíveis para consulta e uso da comunidade interessada. Estes redes são maioritariamente implementadas de forma virtual à exceção do componente responsável pela emissão do sinal rádio, onde serão apresentadas algumas opções para o efeito no decorrer da dissertação. Como alvo de estudo e avaliação do estado de desenvolvimento e utilidade ao longo desta dissertação, foi escolhida a OpenAirInterface de entre esses projetos open-source. É apresentada e descrita a implementação completa da mesma, assim como os testes efetuados no sentido de apurar quais as larguras de banda funcionais e quais as opções de otimização de funcionamento da mesma. Para concluir o trabalho realizado, é apresentado o resultado e balanço desses testes na forma de testes de velocidade e latência em várias larguras de banda, verificação de ocupação da mesma, flexibilidade em modificar a frequência de emissão, assim como o resultado de um teste de conexão de elementos de redes móveis desenvolvidos por projetos open-source diferentes como forma de avaliar a flexibilidade destas redes.Mestrado em Engenharia Eletrónica e Telecomunicaçõe