Μελέτη των πρωτοκόλλων ασύρματης δικτύωσης IEEE 802.11ac & 802.11bgn (Master thesis)
Κυριακούλης, Γεώργιος
Technological developments in wireless networks and the development of
Wireless Local Area Networks (WLANs) in particular, enabled the provision of
services similar to wired networks, which until a few years ago wasn’t possible. The
new standards of the IEEE 802.11 protocol family provide speeds that exceed 1 Gbps
and can support multiple users with multiple connections at the same time.
This diploma thesis aims at presenting the basic features of IEEE 802.11
family protocols, as well as the principles of their operation. It focuses on comparing
the IEEE 802.11ac protocol with its predecessors, presenting its design and operating
mode.
An experiment was carried out, where multiple measurements were made on
different equipment and using various wireless networking protocols. Comparative
results between equipments and protocols are presented and analyzed. This effort has
led to a better understanding of wireless networks and has contributed to the
development of skills enabling the comparison and evaluation of wireless systems and
technologies. During the experiment, measurements were taken with equipment that
did not support the IEEE 802.11ac protocol in all participating devices; however, our
measurements were taken normally, since the goal was to measure and compare the
protocols rather than the devices. In this study, the IEEE 802.11ac protocol was
evaluated in terms of coverage map, signal strength, packet loss and delay and
throughput. Then a comparison was made with analogous measurements of the IEEE
802.11b, IEEE 802.11g and IEEE 802.11n protocols. The use of measurement
software played an important role as it is an additional burden on the measurement
system. The final conclusion is that the results are very different, depending on the
place and the conditions of application. Differentiation was also observed, with the
same parameters and conditions, in the same space, in the same scenario, depending
on the Access Point that was used. In addition to the operating protocol, the hardware
part plays an important role in the wireless network's performance.
| Institution and School/Department of submitter: | Σχολή Τεχνολογικών Εφαρμογών/Τμήμα Μηχανικών Πληροφορικής |
| Subject classification: | Πρωτόκολλα δικτύων ηλεκτρονικού υπολογιστή. Computer network protocols. IEEE 802.11 (Standard) IEEE 802.11 (Πρότυπο) Ασύρματα συστήματα επικοινωνίας Wireless communication systems |
| Keywords: | IEEE 8022.11ac;256QAM;beamforming;spatial streams |
| Description: | Μεταπτυχιακή εργασία--Σχολή Τεχνολογικών Εφαρμογών--Τμήμα Μηχανικών Πληροφορικής,2017--9104 |
| URI: | http://195.251.240.227/jspui/handle/123456789/12332 |
| Table of contents: | Κατάλογος περιεχομένων 1 Εισαγωγή...................................................................................................................13 1.1 ΑσύρματαΔίκτυα 802.11 καιηεξέλιξήτους...................................................14 2 ΟικογένειατωνπρωτοκόλλωνΙΕΕΕ 802.11 ............................................................15 2.1 ΙΕΕΕ 802.11legacy ...........................................................................................15 2.2 ΙΕΕΕ 802.11b ....................................................................................................16 2.3 ΙΕΕΕ 802.11a ....................................................................................................16 2.4 ΙΕΕΕ 802.11g ....................................................................................................17 2.5 ΙΕΕΕ 802.11n ....................................................................................................18 2.6 ΙΕΕΕ 802.11ad ..................................................................................................18 3 IEEE 802.11ac...........................................................................................................19 3.1 ΗτεχνολογίαπουχρησιμοποιείταιστοΙΕΕΕ 802.11ac ..................................21 3.2 ΒΕΛΤΙΩΣΕΙΣΣΤΟΦΥΣΙΚΟΕΠΙΠΕΔΟ..........................................................23 3.3 MIMO................................................................................................................24 3.4 Περισσότερεςχωρικέςροές...............................................................................25 3.5 Beamforming.....................................................................................................25 3.6 Multi-User MIMO (MU-MIMO)......................................................................26 3.7 ΒΕΛΤΙΩΣΕΙΣΣΤΟΕΠΙΠΕΔΟ MAC...............................................................27 3.7.1 Συνένωσηπλαισίων (Frame aggregation) .................................................27 3.7.2 Συνύπαρξηκαιπροςταπίσωσυμβατότητα...............................................28 3.7.3 Channelization...........................................................................................28 3.7.4 Στατικήκαιδυναμικήπρόσβασηκαναλιού...............................................29 3.7.5 Βελτιωμένοςμηχανισμός RTS/CTS..........................................................29 4 ΕπισκόπησηΕρευνητικούΠεδίου - πείραμα.............................................................31 4.1 Συνθήκεςπειράματος.........................................................................................32 4.2 Εργαλείακαιεξοπλισμός...................................................................................33 4.2.1 Server.........................................................................................................33 4.2.2 Laptop 1.....................................................................................................34 4.2.3 Laptop 2.....................................................................................................34 4.3 Λογισμικό .........................................................................................................35 4.3.1 Net Meter...................................................................................................35 4.3.2 Ekahau HeatMapper...................................................................................35 4.3.3 Filezilla.......................................................................................................35 4.3.4 Wireshark...................................................................................................35 4.3.5 InSSIDer....................................................................................................35 4.4 Παραδοχέςκαιπεριορισμοί...............................................................................35 4.5 AP V...................................................................................................................36 4.6 AP C...................................................................................................................37 4.7 AP F...................................................................................................................38 5 Πειραματικήαξιολόγηση..........................................................................................40 5.1 Χάρτηςκάλυψης................................................................................................40 5.2 Κατανοώνταςτα Decibel καιτηχρήσητουςστιςασύρματεςεπικοινωνίες......45 5.2.1 dB (decibel)................................................................................................46 5.3 Εφαρμογή InSSIDer..........................................................................................46 5.4 Λογισμικό Net Meter........................................................................................59 5.5 Access Point F....................................................................................................65 5.6 Access Point C...................................................................................................66 5.7 Access Point V...................................................................................................69 5.8 Διάγραμμαυψηλότερηςκορυφής, 765Mbits....................................................70 5.9 Λογισμικό wireshark..........................................................................................72 5.10 Απώλειατωνπακέτων (PER)..........................................................................73 9 5.11 Μέτρησηκαθυστέρησηςπακέτων (ack_rtt)....................................................76 6 Τεχνικέςλεπτομέρειες ..............................................................................................82 6.1 Εντοπισμόςμεγαλύτερου tcp stream.................................................................82 6.2 Διαδικασίαεύρεσηςποσοστούχαμένωνπακέτων.............................................84 6.3 Μέτρησηκαθυστέρησηςπακέτων (ack_rtt)......................................................86 7 Επίλογος ...................................................................................................................88 7.1 Συμπεράσματα ..................................................................................................88 7.2 Μελλοντικέςεπεκτάσεις ...................................................................................89 8 Βιβλιογραφία.............................................................................................................90 |
| Appears in Collections: | Μεταπτυχιακές Διατριβές |
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