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The WLAN project is a joint enterprise of ACCU, SURFnet and the Computational Physics Workgroup of Utrecht University, in collaboration with DIGITAL and LUCENT. It investigates the characteristics of wireless LAN, a relatively new development, which enables high bandwidth radio communication between computers over a limited range. More precisely: |
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The aim of the WLAN project is to investigate the scalability of the CSMA/CA MAC protocol, as it is defined in the 802.11 standard for wireless LAN communication. |
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The project consists of two approaches; firstly the scaling behaviour was tested by measuring the aggregate throughput for various numbers of clients (up to 25) in a wireless cell. These are described in detail elsewhere. Here, they will only be addressed briefly. This document will mainly report on the second approach; the extrapolation of these data to larger numbers of clients, by means of simulations. To this end, the CSMA/CA protocol was mimicked in a discrete event simulator. The Ptolemy environment by the university of Berkeley was chosen as development platform. The result is a very flexible simulation tool that can be used to closely investigate the CSMA/CA protocol in a wide variety of circumstances. The second part of this introduction will briefly explain the basic ideas of the MAC protocol under investigation. A couple of pages will be devoted to a first reconaissance of the protocols timing properties, using some very simple mathematics. Then, the design philosophy of the simulator and results for an extrapolation of the data to 150 clients will be presented, followed by some conclusions. |
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