ABSTRACT
Mobile users are demanding higher data rate and higher quality mobile communication services. The 3rd Generation Mobile Communication System (3G) is an outstanding success. The conflict of rapidly growing users and limited bandwidth resources requires that the spectrum efficiency of mobile communication systems be improved by adopting some advanced technologies. It has been proved, in both theory and in practice, that some novel key technologies such as MIMO (multiple input, multiple output) and OFDM (orthogonal frequency division multiplexing) improve the performance of current mobile communication systems. Many countries and organizations are researching next-generation mobile communication systems, such as the ITU (International Telecommunication Union), European Commission FP (Framework Program), WWRF (Wireless World Research Forum), Korean NGMC (Next-Generation Mobile Committee), Japanese MITF (Mobile IT Forum), and China Communication Standardization Association (CCSA). International standards organizations are working for standardization of the E3G (Enhanced 3G) and 4G (the 4th Generation Mobile Communication System), such as the LTE (long term evolution) plan of the 3rd Generation Partnership Project (3GPP) and the AIE (air interface of evolution)/UMB (ultramobile broadband) plan of 3GPP2.
