12 Wireless communication ▪802.11b/g ： Wireless internet infrastructure, laptop ▪Support TCP/IP 、 Ethernet, usually 2.4GHz ▪802.11b/11Mbps 、 802.11g/54Mbps, speed 1Mbps transmission distance about 570 meter ▪Router/Bridge types ▪IEEE802.15.4 (ZigBee) : home set, PC, game box, toy ▪2.4GHz, 868MHz (European), 915MHz (US) ▪Transmission distance about 75 meter, 20kbps ～ 250kbps ▪Low power consumption ▪IEEE802.15.1 (blue tooth): m-phone, printer, medical equipment ▪Short distance, 2.4GHz ▪GPRS: bandwidth up to 160 Kbps ▪Criteria: bandwidth, accessible, long term cost, technique popularity, experience