 T. Rautiainen, and K. Kalliola. based on dominant paths [Yee66] K. S. Yee. Numerical solution of Path loss models for urban between transmitter and initial boundary value problems microcells at 5.3 GHz. COST receiver in indoor wireless involving Maxwell's equations in 273, TD(04)207, Duisburg, communications. In Proc. Germany, Sep. 2004. EPMCC 1997-2nd European This page intentionally left blank Section Five Short range wireless communication This page intentionally left blank Chapter 5.1 Wireless local area networks Daniel Dobkin 5.1.1 Networks large and small links also need low error rates, because the time required to correct an error is long. Shorter links can take a dif- Although this book is primarily about voltages and waves, ferent approach, sending a packet and then waiting for to make the text reasonably self-contained, we provide a response, because the time required is not large. Small a brief introduction into the topic of networking in gen- and large networks are also practically and commercially eral and review the characteristics of several wireless distinct: small networks are usually owned and operated local network technologies. In this review, the reader will by their users, whereas large networks are owned and encounter real examples of how the common concepts operated by service providing companies who are not the are put to use in getting data from one place to another primary users of their capacity. wirelessly. With that brief preface, let us categorize data net- Our treatment is necessarily cursory and emphasizes works by size: aspects relevant to our main topic of wireless trans- Personal area networks (PANs): PANs extend a few mission and reception, giving short shrift to frame for- meters and connect adjacent devices together. To mats, management entities, and many other topics speak formally, a data connection between a single directed toward network implementation. transmitting station and a single receiving station is Data networks have existed in various forms since a link, not 