Design and Realization of a Prototype Hardware Platform for ...

The MegaWatch Wireless PlatformMaster's Thesis - Emanuel Corthay3 BackgroundFigure 3 A self-organized, Wireless Ad Hoc NetworkToday, there are no mass market products using this technique. But a lot of research is takingplace, and it will likely become tomorrow’s network architecture of choice.It is important to keep in mind that the infrastructure will not simply disappear. Rather, the selforganizednetwork will be used to access the nearest fixed wireless gateway. This gateway willlink the Ad-Hoc network with a larger, long-distance communication infrastructure when necessary.More information on Ad-Hoc networks can be found in [2].3.3 Possible ApplicationsIf we succeed in providing watch size, wearable, distributed wireless communication nodes, thefollowing applications could become common in the future:• Support for helping people to meet (find them, determine who’s around)• Localisation and orientation(map, directions, emergency like avalanche, …)• Text messaging and paging• Local information (cafeteria menu, on-site events, weather forecast, e-shop, roomreservation, on-site white pages, …)• Revolutionary classroom support (instant polling, paperless course slides annotations, …)• Emergency call to anybody around• Address book and planner synchronisation/sharing3.4 Existing StandardsSeveral wireless standards already exist, or are being actively developed.The largest wireless network in place is the well known GSM cell phone system. It reliesexclusively on an operator architecture, composed of many base stations distributed across acountry’s territory. Phone-to-phone wireless communications are not possible.The WiFi, or wireless LAN, based on the IEEE 802.11 standard is a popular wireless computernetwork. Today, most laptops come with an embedded wireless card. They can communicatedirectly with each other in Ad-Hoc mode, or with a base station that anyone can buy from acomputer reseller. A lot of experiments have already been conducted based on off-the-self 802.11components, but their functionalities are limited to the standard. It is thus not possible to modifythe way they interact with each other to test new transmission systems. Moreover, they aredesigned for high speed data links, going up to 54 Mbps for recent models, and are not suitable forlow-power applications.Bluetooth[3] is another standard, dedicated to very short distances, low data ratecommunications. It is intended as a replacement for cable connexions between devices at homeor in the office. Its range is limited to a maximum of 10 meters, and its data rate is of the order of11 / 83