Delovanje brezžičnega lokalnega omrežja znotraj stavb

GAŠPERLIN, BLAŽ (author), STERLE, JANEZ (mentor)

Brezžična tehnologija razvita za lokalna omrežja, poznana pod sinonimom Wi-Fi, je danes najbolj pogosta brezžična tehnologija, uporabljena v sodobnih mobilnih terminalih in napravah interneta stvari. Cilj diplomske naloge je bil analizirati delovanje tehnologije Wi-Fi znotraj različnih stavb ter ugotoviti kakšen vpliv imajo sami materiali (vrsta materiala, oddaljenost od dostopne točke in število sten) na propagacijo radijskega signala. V okviru teoretičnega dela diplomske naloge smo tako analizirali delovanje tehnologije Wi-Fi s poudarkom na propagaciji radijskega signala v stavbah ter interferencah med ostalimi tehnologijami v nelicenčnem področju ISM. V poglavju 2, se nahaja kratek pregled brezžičnih tehnologij v industrijskem, znanstvenem in medicinskem frekvenčnem pasu ISM, kateremu sledi poglavje s pregledom standardov IEEE 802.11. V poglavju 4 smo bolj podrobno analizirali najnovejši standard IEEE 802.11ac, ki je izšel v letu 2015. Sledi pregled Wi-Fi radijskega spektra z analizo frekvenčnih pasov 2.4 GHz in 5 GHz. V poglavjih 6 in 7 pa so podani postopki za sodostop do radijskega kanala ter analiza vzrokov, ki lahko omejujejo propagacijo radijskega signala in povzročajo interference znotraj stavb. V praktičnem delu diplome smo preverjali propagacijske lastnosti radijskega signala znotraj stavb, ki smo jih izvedli na osnovi meritev omrežij Wi-Fi, ki so delovala po standardu IEEE 802.11ac in IEEE 802.11n. Bolj podrobno nas je zanimal nivo signala oziroma moč RSSI v odvisnosti od oddaljenosti od dostopovne točke ter nivo signala v odvisnosti od števila sten, ki so se nahajale v posamezni stavbi. Opravili smo tudi meritve hitrosti proti uporabniku in hitrosti od uporabnika ter zakasnitve z orodjem Ping. Za izvedbo praktičnega dela smo uporabili Android mobilni terminal z naloženo aplikacijo AKOS Test Net, dostopni točki Wi-Fi, ki sta podpirali standard 802.11n in 802.11ac ter prenosni računalnik, z naloženim odprtokodnim programom inSSIDer za spremljanje interferenc sosednjih omrežij na 2.4 GHz frekvenčnem pasu. Za spremljanje interferenc na 5 GHz frekvenčnem pasu, pa smo uporabili odprtokodno aplikacijo Wifi Analyzer, naloženo na Android mobilni terminal. V zaključku so predstavljeni ključne ugotovitve in rezultati meritev ter podane smernice nadaljnega razvoja brezžičnih lokalnih omrežij.

• Language: Slovenian
• Keywords: Brezžično lokalno omrežje, Wi-Fi, delovanje omrežja, propagacija, meritve, propustnost, standardi, 802.11ac, radijski spekter
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2016
• PID: 20.500.12556/RUL-84503
• Publication date in RUL: 26.08.2016

Secondary language

• Language: English
• Title: Operation of wireless local area networks inside buildings

Abstract

Wireless technology developed for Local Area Networks, known as Wi-Fi, is today the most common wireless technology used in modern mobile terminals and devices of IoT. The aim of this study was to analyze the functioning of Wi-Fi technology within the various buildings and determine what impact they have their own materials (material type, distance from the access point and the number of walls) on the propagation of radio signals. Within the theoretical part of the diploma thesis we analyzed the operation of Wi-Fi technology, with an emphasis on the propagation of radio signals in buildings and the interference of the other technologies in unlicensed ISM field. In the initial part of the thesis, in Chapter 2, is a brief overview of wireless technologies in the ISM frequency band, followed by an overview of the IEEE 802.11 standards, in Chapter 3. In Chapter 4, we present the latest IEEE 802.11ac standard, which was published in 2015 and we devote a little more attention. Furthermore, in Chapter 5, is described a Wi-Fi radio spectrum and the frequency bands 2.4 GHz and 5 GHz. In Chapters 6 and 7 follows the procedures for shared access to the radio channel, followed by a description of the propagation of radio signal and interferences. The main objective was to compare the propagation of radio signal with the measurement between the IEEE 802.11ac and IEEE 802.11n standards, which we were interested in the signal level or RSSI as a function of the distance from the access point, and the signal level depending on the number of walls, which were placed in individual building. We also made measurements of download speed and upload speed and latency (Ping). To achieve the goal, I used Android mobile terminal with a downloaded application AKOS Test Net, through which I performed measurements, the access points, which supports standard 802.11n and 802.11ac and a laptop loaded with open source software inSSIDer for monitoring the interference between neighboring networks at 2.4 GHz frequency band. In order to monitor interference on the 5GHz frequency band, we used open source application Wifi Analyzer, loaded on the Android mobile terminal, because, used laptop did not support the 5 GHz frequency band, but only the 2.4 GHz frequency band. In the conclusion of this diploma thesis are presented key findings and results of the measurements and the guidelines for further development of wireless Local Area Networks.

• Keywords: Wireless Local Area Network, Wi-Fi, Network operation, propagation, measurements, throughput, standards, 802.11ac, radio spectrum