University of Oulu

Comparative study of increasing indoor WLAN coverage by passive repeating systems

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Author: Rahaman, Sadiqur1
Organizations: 1University of Oulu, Faculty of Information Technology and Electrical Engineering, Communications Engineering
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2 MB)
Pages: 61
Persistent link:
Language: English
Published: Oulu : S. Rahaman, 2018
Publish Date: 2018-09-14
Thesis type: Master's thesis (tech)
Tutor: Pärssinen, Aarno
Reviewer: Sonkki, Marko
Pärssinen, Aarno


Propagation of radio waves is interrupted while traveling through different materials. The architectural beautification and complexity by using various building materials cause attenuation of the signal via indoor, outdoor to indoor and vice versa wireless communications. It has been found that feeding more power to the transmitter or increasing sensitivity of the receiver is one of the solutions to overcome weak connectivity. However, this approach is not cost effective. Another concern is the ability to amplify the wireless signal, especially in WLAN operation. WLAN is one of the most popular ways of establishing a wireless communication network to connect our daily used devices such as mobile phone, laptop, IP camera etc. Path loss, attenuation by materials and the delivered power from the transceiver are the variables to determine the efficiency of this communication network.

A passive repeating method has been discussed in this thesis which addresses the mentioned concerns. It is cost effective and in a case of power consumption, does not need any energy outside the system. On the other hand, there are few maintenance costs, if any, for this kind of system. To achieve this, a back-to-back antenna approach has been tested in this study. In a back-to-back system, two antennas are connected by a short waveguide connection to decrease attenuation e.g. a wall. The main challenge concerning the effectiveness of this method was to design and fabricate efficient antennas, which are connected with a coaxial cable.

There are multiple frequency bands available for WLAN communication. In this thesis, a frequency of 2.43 GHz is considered. Computer simulation of antennas, fabrication, individual measurement and full passive repeating system measurement has been presented. A prototype of a circular patch antenna is built with a 4.63 dB gain and a return loss of 15.18 dB. The passive repeating system is built by using a commercially available dipole antenna at the other end of the coaxial cable. In various cases, there was an observable improvement of the signal of between 2 dB to 6 dB.

Required background and theoretical studies are presented along with the output of the simulated and measured prototype comparison. It is clear from this study that the passive repeating system can be used in some specific indoor areas.

Keywords: WLAN, passive repeater, path loss, attenuation, indoor communication.

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Copyright information: © Sadiqur Rahaman, 2018. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.