Wireless Tech Outline What is wireless Why wireless

Wireless Tech 第八組 張維倫

Outline • • • What is wireless Why wireless Architecture of wireless LAN Comparison Summary

What is wireless • Connection without wire

Why wireless • No Wiring Hassle –沒有線 • High Mobility –可以走來走去 • 網路規劃較簡單

Architecture (1) -- Infrastructure WH AP • Infrastructure – – – • 就像手機的 – – – BSS AP (Access Point) WH (Wireless Host) BSS (Basic Service Set) 基地台 手機 服務範圍

Architecture (2) – Ad Hoc Network • • • No AP Host 直接連線 其中一台是虛擬 server

Hidden terminal problem • CSMA/CA -- Carrier Sense Multiple Access with collision avoidance

Wireless tech • Microwave • RF • Infrared ray

Microwave • • Reflection antenna Point to Point Static Ex. NTUCC TA Net

Infrared • Short range • Line of sight • Ex. 電視遙控器

RF tech • • Wi. Fi 802. 11 a/b/g 3 G Bluetooth Zig Bee UWB (ultra wide band) Home. RF Hyper. LAN

RF tech (cont. ) • • Power Unlicensed band vs. licensed band Data rate Range

Power

Data Rate

Range

Comparison Bluetooth Ir. DA 市場定位 短距個人通 訊 利用頻率 802. 11 a/b/g Hyper. LAN Home. RF 短距、直線， 區域網路 個人通訊 區域網路 家庭網路 2. 4 GHz 波長 820 mm 2. 4 GHz/5 G Hz 5 GHz 2. 4 GHz 傳送速度 723 kbps 4/16 Mbps 54/11/54 Mb ps 54 Mbps 0. 8/1. 6 Mbps 傳送距離 10 M 3 -5 M 100 M 30 M/150 M( outdoor) 50 M 語音的傳遞 yes no no yes