Tutorial: OFDM and MC-CDMA for Future High Rate Wireless Communications

Abstract

The success of multi-carrier communications (OFDM) in high rate wireless communications started with its deployment in digital broadcasting standards like DAB and DVB-T. Followed by its promising application in wireless local area networks (WLANs) like IEEE 802.11a and HIPERLAN/2, OFDM is a key candidate for the data transmission of next generation (4G) broadband mobile radio systems where data rates of 100 Mbit/s and higher are targeted. This tutorial provides an understanding of the principle of OFDM and gives an overview on multi-carrier based broadcasting and WLAN standards as well as on novel concepts for 4G mobile radio. Potential multi-carrier multiple access schemes for future wireless communications like MC-CDMA, OFDMA and derivatives are detailed and its signal design and multi-user detection techniques are explained. A comparative analysis with respect to performance and flexibility shows the strengths and weaknesses of the individual multiple access schemes. The exploitation of spatial diversity in OFDM and MC-CDMA systems by different MIMO concepts is presented. Finally, important implementation issues in OFDM systems like synchronization and channel estimation as well as the effects of non-linear amplifiers and phase noise of the oscillators are addressed.