专业英语4G.pptx

陈旭 2012082401 葛云鹏 2012082403 Outline Evolution What is 4G 4G Transmission Protocols The advantages and disadvantages 3G vs 4G Conclusion Evolution First Generation (1G): 1G wireless mobile communication systems, was introduced in the early 1980s. 1G wireless was analog and supported the first generation of analog cell phones. They include a signaling protocol known as SS7 (Signaling System 7). Analog Cellular network Evolution Second Generation (2G): Analog → Digital 2G systems, fielded in the late 1980s, were intended primarily for voice transmission and was all about digital PCS. GSM（Global System For Mobile Communications） Evolution Evolution Third Generation (3G): Circuit Switching → Packet Switching 3G in wireless will be a deliberate migration to faster, data-centric wireless networks. The immediate goal is to raise transmission speeds from 125kbps to 2M bit/sec. WHAT IS 4G ? 4G can be imagined as an integrated wireless system that enables seamless roaming between technologies. A user can be operating in cellular technology network and get handed over to a satellite-based network and back to a fixed wireless network,depending upon the network coverage and preference of charging. 4G Transmission Protocols ■OFDM（Orthogonal Frequency Division Multiplexing） ■ W-OFDM（Wideband Orthogonal Frequency Division Multiplexing） ■ MC-CDMA (Multi Carrier - Code Division Multiple Access) ■ LAS-CDMA (Large Area Synchronized Code Division Multiple Access) The Advantages ■Amazing Speed ■More Coverage ■Complete Privacy, Security and Safety ■ Prices are cutting The Disadvantages ■ Limited to certain specified carriers and regions.  ■ New equipment have to be installed ■ Larger mobile devices 3G vs 4G ■Predominantly voice driven data was always add on ■ Wide area cell based ■ Back compatible to 2G 3G 4G ■ Converged dataand voice over IP ■ Hybrid Integration of Wireless LAN (WiFi ,Bluetooth) and wide area ■ Extend 3G capacity by one order of ma