Over-the-air test configurations for MIMO in Long Term Evolution

One of the main challenges for the mobile industry is the growing demand for the high speed mobile data. The 3GPP (3rd Generation Partner Project) is the organization that specifies most mobile data communication standards used globally. For the demand for high data rates, 3GPP has specified LTE (Long Term Evolution). One solution included in LTE among many is the MIMO (Multiple Input Multiple Output) technology. This thesis discusses the basic features included in LTE Release 9 focusing on MIMO-technology. This thesis also discusses the MIMO-OTA (Over-the-Air) testing configurations introduced in 3GPP Technical Report 37.976. These configurations are divided into two main types: anechoic chamber-based environments and reverberation chamber-based environments. 3GPP divides these two methods into five different anechoic chamber methods and two reverberation chamber methods. Testing MIMO-technology in LTE introduces new requirements for OTA-testing. While test requirements for GSM and WCDMA networks have included TRS (Total Radiated Sensitivity) and TRP (Total Radiated Power), the LTE MIMO testing adds the requirements for throughput testing. When using MIMO-configurations, the throughput depends on power transmitted to UE (User Equipment) that depends on the position of the UE. Addition to that, the throughput also depends on used TM (Transmission Mode). So test specifications need to include throughput tests for all TMs. Performance of TMs and the overall performance of MIMO cannot be tested in traditional OTA-measurement chambers because the transmission channels in traditional OTA-chambers are configured to be as simple as possible, so that the power and sensitivity measurements could be repeatable. Suggestions for LTE testing chambers have included configuring the transmission channel to be more versatile. This has been achieved by methods such as using multiple antennas or including a channel emulator to the system. Using these methods, the UE’s MIMO performance can be tested in different channel environments in laboratory, therefore improving possibilities for research and development.Opinnäytetyössä tutkittiin LTE-teknologian perusperiaatteita keskittyen siihen sisälletyn MIMO-tekniikan toimintaan. Opinnäytetyö tutki myös 3GPP:n TR 37.976 -raportissa esiteltyjä testausympäristövaihtoehtoja. Nämä jakautuvat 2 pääkategoriaan: kaiuttoman kammion järjestelmiin ja heijastavan kammion järjestelmiin. 3GPP jakaa nämä vielä 5:een eri kaiuttoman kammion järjestelmään ja 2:een heijastamattoman kammion järjestelmään. MIMO-tekniikan testaaminen LTE-teknologiassa asettaa suuria vaatimuksia OTA-testaamiselle. GSM- ja WCDMA-verkkojen testaamiseen ovat riittäneet vain herkkyysmittaukset (Total Radiated Sensitivity, TRS) ja tehomittaukset (Total Radiated Power, TRP). LTE:n MIMO-tekniikka lisää testausvaatimuksiin tiedonsiirtonopeuden, joka on MIMO-tekniikkaa käytettäessä riippuvainen herkkyydestä ja lähetetystä sekä vastaanotetusta tehosta, jotka riippuvat puhelimen asennosta. Näiden lisäksi tiedonsiirtonopeus riippuu myös MIMO:n käyttämien siirtotapojen (Transmission Mode, TM) toiminnasta. Siirtotapojen ja MIMO:n toimintaa ei pystytä testaamaan perinteisissä OTA-mittauskammioissa, sillä näissä siirtokanava on yritetty tehdä yksinkertaiseksi, jotta tehojen ja herkkyyden mittaukset olisivat mahdollisimman toistettavia. LTE:n MIMO-testauksen vaatimissa mittauskammioissa on pyritty tekemään siirtokanavasta mahdollisimman monimuotoinen. Tähän on pyritty eri ympäristövaihtoehdoissa erilaisin menetelmin, kuten käyttäen useaa antennia tai kanavaemulaattoria. Tällöin pystytään testaamaan laitteen MIMO:n toimintaa erilaisissa reaalimaailman ympäristöissä laboratorio-olosuhteissa

INTERFERENCE MANAGEMENT IN LTE SYSTEM AND BEYOUND

The key challenges to high throughput in cellular wireless communication system are interference, mobility and bandwidth limitation. Mobility has never been a problem until recently, bandwidth has been constantly improved upon through the evolutions in cellular wireless communication system but interference has been a constant limitation to any improvement that may have resulted from such evolution. The fundamental challenge to a system designer or a researcher is how to achieve high data rate in motion (high speed) in a cellular system that is intrinsically interference-limited. Multi-antenna is the solution to data on the move and the capacity of multi-antenna system has been demonstrated to increase proportionally with increase in the number of antennas at both transmitter and receiver for point-to-point communications and multi-user environment. However, the capacity gain in both uplink and downlink is limited in a multi-user environment like cellular system by interference, the number of antennas at the base station, complexity and space constraint particularly for a mobile terminal. This challenge in the downlink provided the motivation to investigate successive interference cancellation (SIC) as an interference management tool LTE system and beyond. The Simulation revealed that ordered successive interference (OSIC) out performs non-ordered successive interference cancellation (NSIC) and the additional complexity is justified based on the associated gain in BER performance of OSIC. The major drawback of OSIC is that it is not efficient in network environment employing power control or power allocation. Additional interference management techniques will be required to fully manage the interference.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

THROUGHPUT OPTIMIZATION AND ENERGY ENHANCEMENT IN MASSIVE MIMO SYSTEMS

For the last few decades mobile technologies have undergone enormous transformation. Mobile broadband for cellular networks has been exponentially evolving with time and in order to meet the future expectation for this high demand newer and better technologies have to be invented. The enormous success of smart electronics such as tablets, smart phones and other hand held devices that use the Internet have generated a lot of Internet traffic therefore, diving LTE to its limit. LTE (4G) which is a high speed wireless communication standard for mobile phones and data terminals is a significant upgrade of GSM and UMTS network technologies. The Technology has downlink peak rates of 300Mbits/s and Uplink peak rates of 75Mbits/s with transfer latency rate of less than 5ms. Power Consumption level for LTE is of significant concern as well as the energy consumption in cellular networks. To solve the limitations in LTE, one great candidate is 5G radio standard. 5G relies heavily on massive MIMO to achieve its targets. This thesis looked into significance of Multi-antenna (Massive MIMO) at the BS as a solution for energy efficiency, increased data rates and the reduction of latency rates in wireless broadband communication. And the simulation results proved that Massive MIMO has better performance compared to conventional MIMO.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843

Implementação e avaliação no system generator de um sistema cooperativo para os futuros sistemas 5G

With the arrival of 5G it is expected the proliferation of services in the different fields such as healthcare, utility applications, industrial automation, 4K streaming, that the former networks can not provide. Additionally, the total number of wireless communication devices will escalate in such a manner that the already scarce available frequency bandwidth won’t be enough to pack the intended objectives. Cisco’s Annual Internet Report from 2018 predicts that by 2023 there will be nearly 30 billion devices capable of wireless communication. Due to the exponential expiation of both services and devices, the challenges upon both network data capacity and efficient radio resourse use will be greater than ever, thus the urgency for solutions is grand. Both the capacity for wireless communications and spectral efficiency are related to cell size and its users proximity to the access point. Thus, shortening the distance between the transmitter and the receiver improves both aspects of the network. This concept is what motivates the implementation of heterogeneous networks, HetNets, that are composed of many different small-cells, SCs, overlaid across the same coexisting area of a conventional macro-cell, shortening the distance between the cell users and its access point transceivers, granting a better coverage and higher data rates. However, the HetNets potential does not come without any challenges, as these networks suffer considerably from communication interference between cells. Although some interference management algorithms that allow coexistence between cells have been proposed in recent years, most of them were evaluated by software simulations and not implemented in real-time platforms. Therefore, this master thesis aims to give the first step on the implementation and evaluation of an interference mitigation technique in hardware. Specifically, it is assumed a downlink scenario composed by a macro-cell base station, a macro-cell primary user and a small cell user, with the aim of implementing an algorithm that eliminates the downlink interference that the base station may cause to the secondary users. The study was carried out using the System Generator DSP tool, which is a tool that generates code for hardware from schematics created in it. This tool also offers a wide range of blocks that help the creation, and fundamentally, the simulation and study of the system to be implemented, before being translated into hardware. The results obtained in this work are a faithful representation of the behavior of the implemented system, which can be used for a future application for FPGA.Com a chegada do 5G, espera-se a proliferação de serviços nas mais diversas áreas tal como assistência médica, automação industrial, transmissão em 4k, que não eram possíveis nas redes das gerações anteriores. Além deste fenómeno, o número total de dispositivos capazes de conexões wireless aumentará de tal maneira que a escassa largura de banda disponível não será suficiente para abranger os objetivos pretendidos. O Relatório Anual de 2018 sobre a Internet da Cisco prevê que até 2023 haverá quase 30 bilhões de dispositivos capazes de comunicação sem fio. Devido ao aumento exponencial de serviços e dispositivos, os desafios sobre a capacidade de dados da rede e o udo eficiente dos recursos de rádio serão maiores que nunca. Por estes motivos, a necessidade de soluções para estas lacunas é enorme. Tanto a capacidade da rede e o uso eficiente do espectro de frequências estão relacionados ao tamanho da célula e à proximidade dos usuários com o ponto de acesso da célula. Ao encurtar a distância entre o transmissor e o recetor ocorre um melhoramento destes dois aspetos da rede. Este é o principal conceito na implementação de redes heterogéneas, HetNets, que são compostas por diversas células pequenas que coexistem na área de uma macro célula convencional, diminuído a distância entre os utilizadores da célula e os pontos de acesso, garantindo uma melhor cobertura e taxa de dados mais elevadas. No entanto, o potencial das HatNets não vem sem nenhum custo, pois estas redes sofrem consideravelmente de interferência entre as células. Embora nos últimos anos foram propostos alguns algoritmos que permitem a coexistência das células, a maioria destes foi só testado em simulações de software e não em plataformas em tempo real. Por esse motivo, esta dissertação de mestrado visa dar o primeiro passo na implementação e a avaliação de uma técnica de mitigação de interferência em hardware. Mais especificamente no cenário de downlink entre uma estação base de uma macro célula, um utilizador primário da macro célula e um utilizador secundário de uma célula pequena, com o principal objetivo de cancelar a interferência que a estação base possa fazer ao utilizador secundário. O estudo foi realizado utilizando a ferramenta System Generator DSP, que é uma ferramenta que gera código para hardware a partir de esquemáticos criados na mesma. Esta ferramenta também oferece uma vasta gama de blocos que ajudam a criação, e fundamentalmente, a simulação e o estudo do sistema a implementar antes de ser traduzido para hardware. Os resultados obtidos neste trabalho são uma fiel representação do comportamento do sistema implementado. O quais podem ser utilizados para uma futura aplicação para FPGA.Mestrado em Engenharia Eletrónica e Telecomunicaçõe