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

Network capacity optimisation in millimetre wave band using fractional frequency reuse

Inter Cell Interference (ICI) is a major challenge that degrades the performance of mobile systems, particularly for cell-edge users. This problem arises significantly in the next generation system, as the trend of deployment is with high densification, which yields an ultra-dense network (UDN). One of the challenges in UDN is the dramatic increase of ICI from surrounding cells. A common technique to minimise ICI is interference coordination techniques. In this context, the most efficient ICI coordination is fractional frequency reuse (FFR). This paper investigates the FFR in UDN millimetre wave network at 26GHz band. The focus is on dense network with short inter site distance (ISD), and higher order sectorisation (HOS). The metrics used in frequency reuse is the signal to interference plus noise ratio (SINR) rather than the distance, as the line of sight in millimetre wave can be easily blocked by obstacles even if they are in close proximity to the serving base station. The work shows that FFR can improve the network performance in terms of per user cell-edge data throughput and average cell throughput, and maintain the peak data throughput at a certain threshold. Furthermore, HOS has a potential gain over default sectored cells when the interference is carefully coordinated. The results show optimal values for bandwidth split per each scenario in FFR scheme to give the best trade-off between inner and outer zone users performance

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

Uplink CoMP Capability Improvements In Heterogeneous Cellular Networks

LTE-Advanced meets the challenge raised by powerful, mobile devices and bandwidth-hungry applications by investing in solutions such as carrier aggregation, higher order MIMO, relay nodes and Coordinated Multipoint (CoMP) transmission/reception. The latter, in particular, is envisioned to be one of the most important techniques in LTE-Advanced to improve the throughput and functionality of cell borders. CoMP allows users to have multiple data transmission and reception from/toward multiple cooperating eNodeBs (eNBs), increasing the utilization factor of the network. Resource allocation in the uplink is especially beneficial because more sophisticated algorithms can leverage the availability of additional connection points where the signal from the User Equipment (UE) is processed, ultimately providing UEs with increased throughput. Additionally, a significant part of the interference caused by neighboring cells can be seen as a useful received signal thanks to CoMP, provided those cells are part of the Coordinated Reception Point (CRP) set. This is especially important in critical regions, in terms of interference, like cell edges. Finally, in the case of joint multi-cell scheduling, CoMP introduces a reduction in the backhaul load by requiring only scheduling data to be transferred between coordinated eNBs. Arguably, CoMP is most appealing in the uplink direction since it does not require UE modifications: indeed, users need not be aware that there is any kind of cooperation among receiving eNBs. UEs are merely scheduled for transmission on a set of frequencies that happens to be split among different eNBs, although they still retain standard signaling channels through only one of these eNBs, usually referred to as the serving cell. In this work we focus on uplink CoMP from a system point of view. Specifically, we are interested in comparing through simulation the performance of uplink CoMP in various scenarios with different user participation to CoMP transmissions and CoMP margins. Some works have already investigated uplink CoMP both in simulation and through field trials. Our contribution confirms the findings of previous works as far as the throughput gain for edge users is concerned, but introduces three novel observations that can spur future investigations on CoMP systems, in both downlink and uplink regime, and lead to the design of new resource allocation algorithms: • We look at Heterogeneous scenario where there is no restriction in the type of cells that can be in the CRP set, but simultaneously we introduce clustering option included limited number of Macro and small cells to be acted independently from other clusters in CoMP process. • We introduce a parameter called CoMP Pool Percentage (CPP), which quantifies the fraction of PRBs that are reserved for UEs using a specific eNB as CRP (out of the resources nominally available to that eNB). Our algorithm show that the setting of CPP must be carefully gauged depending on the number of CoMP users and the scenario. • We proposed an innovative dynamic algorithm to make decision of the CPP value in order to improve the gain for CoMP users while considering the whole network gain. Combination of the three above mentioned routine and algorithms, according to simulations, confirms an average gain of at least 20% percent for the CoMP users, (average over various population) locating in cell boarder, while the whole network benefits by average of 5% gain for all the users (see results section). The algorithm also guarantees more gain for more values of CoMP margin. In other words, the more the population of CoMP users locating in cell borders the more would be the achievable gain. Objectives of this PhD thesis are concluded as follows: • Design a Network-level simulator whose features are close to a real LTE network, including advanced capabilities and innovations • Observe the response of the network to parameters changes • Increase the throughput gain (using CoMP vs. non using it) and the quality of service • Design and evaluate the Novel Scheduling Algorithm • Compare the obtained results with real case

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

Millimetre wave frequency band as a candidate spectrum for 5G network architecture : a survey

In order to meet the huge growth in global mobile data traffic in 2020 and beyond, the development of the 5th Generation (5G) system is required as the current 4G system is expected to fall short of the provision needed for such growth. 5G is anticipated to use a higher carrier frequency in the millimetre wave (mm-wave) band, within the 20 to 90 GHz, due to the availability of a vast amount of unexploited bandwidth. It is a revolutionary step to use these bands because of their different propagation characteristics, severe atmospheric attenuation, and hardware constraints. In this paper, we carry out a survey of 5G research contributions and proposed design architectures based on mm-wave communications. We present and discuss the use of mm-wave as indoor and outdoor mobile access, as a wireless backhaul solution, and as a key enabler for higher order sectorisation. Wireless standards such as IEE802.11ad, which are operating in mm-wave band have been presented. These standards have been designed for short range, ultra high data throughput systems in the 60 GHz band. Furthermore, this survey provides new insights regarding relevant and open issues in adopting mm-wave for 5G networks. This includes increased handoff rate and interference in Ultra-Dense Network (UDN), waveform consideration with higher spectral efficiency, and supporting spatial multiplexing in mm-wave line of sight. This survey also introduces a distributed base station architecture in mm-wave as an approach to address increased handoff rate in UDN, and to provide an alternative way for network densification in a time and cost effective manner