Đây là hệ số phản xạ của bề mặt mái nhà xe. Khoảng cách từ điểm nhiễu xạ cho thiết bị đầu cuối được cho bởi phương trình sau, Đại diện tỷ lệ của các mức công suất nhận được của hai tia với một có thể tính toán độ sâu tối đa phai trong dB | Chapter 12 WmELESS LANs NETWORK DEPLOYMENT IN PRACTICE R. P SAD ALBERT EIKELENBOOM HENRI MOELARD AD I ME IANANDNEELI PRASAD Wireless Communications and Networking Division Lucent Technologies Nieuwegein The Netherlands Abstract Wireless LANs most commonly use the Industrial Scientific and Medical ISM frequency band of GHz. Although there have been a variety of proprietary solutions the IEEE approved a standard that organizes hi technology. Planning the network which fulfills the requirements of the user m such systems is a major issue. In this chapter we will discuss some critical issues faced during wireless LAN deployments from a practical point of view. 236 Chapter 12 1. INTRODUCTION Proliferation of computers and wireless communication together has brought us to an era of wireless networking. Continual growth of wireless networks is driven by to 1OTC a few case to rn all flexibility and mobility. These benefits offer gains in efficiency accrnacy and lower business costs. The growth in the market brought forward several proprietary standards for Wireless Local ea Networks ANs tins chaos was resolved by hamonizing effort of IEEE with an international standard on WLANs IEEE 1 . Wireless LANs in a Nutshell Wireless LANs mostly operate using either radio technology or infrared techniques. Each approach lias it own attribute which satisfies different connectivity requirements. Majority of these devices are capable of transmitting information up to several I X meters in an open dnvironment. In figure 1 a concept ofWLAN iwterfacing with a wired network is given. The components of VI A s consist of a wireless network interface card often known as station STA and a wireless bridge referred to as access point AP. The AP interface the wireless network with the wired network . Ethernet L 1 2 3 Figure 1. A wireless local area network. Wireless LAN Deployment in Practice 237 The most widely used WLANs use radio waves at the frequency band of GHz .
