Multimedia services such as Web browsing, video on demand, and IP telephone delivered to the office and home by wired network systems such as optical fiber systems and ADSL systems are now very popular. This popularity increases the demand for more powerful technologies to provide radio access such as high data rate, QoS controlling. The 3rd generation wireless system already has the ability to provide such multimedia services, but advancement of radio access is necessary for stress-free operation. In this paper, we summarize the requirements for next-generation radio access schemes to be put in place around 2010. A high data rate is the most important requirement for multimedia services. Orthogonal frequency division multiplexing (OFDM) in combination with multiple input multiple output (MIMO) multiplexing is considered to be the method most likely to satisfy this requirement. Here, we introduce some advanced technologies that help improve the transmission data rate and the spectral efficiency for the next-generation wireless systems.
