tailieunhanh - Điện thoại di động băng thông rộng không dây P8

Who Needs 4G? What is 4G? Social Background and Future Trends There has been an evolutionary change in mobile communication systems every decade. The increase in the number of subscribers and transmission data rates leads to a shift to higher frequency bands where wider bandwidth is available. There are two directions for future trends in mobile communications. | Broadband Wireless Mobile 3G and Beyond. Edited by Willie W. Lu Copyright 2002 John Wiley Sons Ltd. ISBN 0-471-48661-2 5 Initiatives in 4Gmobile Design Introduction - Who Needs 4G What is 4G Social Background and Future Trends There has been an evolutionary change in mobile communication systems every decade. The increase in the number of subscribers and transmission data rates leads to a shift to higher frequency bands where wider bandwidth is available. There are two directions for future trends in mobile communications. One is Direction A which aims to increase transmission data rates where the same mobility as IMT-2000 from indoor to high speed vehicles is maintained. The other is Direction B which aims to expand mobility from indoor to outdoor where the transmission data rates in the wireless access systems are maintained. Direction B will be suitable for spot area services in order to satisfy the demand for higher data rates while Direction A will accommodate continuous area services. We focus on Direction A here. The number of subscribers using PDC and PHS in Japan was million in October 2000 and has increased by 10 million for 5 successive years. One in mobile phone users connected to the Internet in October 2000. This pattern of use has increased significantly and Internet use is expected to comprise 90 percent of all mobile communication traffic in 2005. The US and Europe are expected to follow a similar trend. Figure shows a traffic forecast for Region 3 97 . From 1999 through 2010 subscribers to voice-oriented services are expected to grow by times and the ratio between voice and multimedia traffic will be nearly 1 2 for total up- and downlinks. Assuming that multimedia traffic grows by 40 percent a year after 2010 it will be 23 times that of 1999 and the ratio between voice and multimedia traffic will be about 1 10. Therefore to accommodate the considerable multimedia traffic after 2010 we must conduct R D on key technologies