Technologies for 3G wireless communications

Abstract

This paper discusses and compares three prominent contenders for 3G wireless communication. These are the OFDM, CDMA, and MC-CDMA -a hybrid of the first two. OFDM, i.e., the Orthogonal Frequency Division Multiplexing technique, has gained increasing acceptance as an alternative to single carrier modulation for wireless systems. Potential exists for very high bit rates and for reaching the channel capacity even over frequency-selective fading channels. CDMA, i.e., Code Division Multiple Access, is the technique being most seriously considered for 3G wireless systems. It uses PN sequences to spread the signal spectrum to a wideband thereby achieving robustness to the deep fades than a narrowband signal, and the capability for multiple-user access. The third technique, MC-CDMA, uses a combination of the above two, and has some advantages as will be pointed out in the paper. Finally, the paper will touch upon an application, namely wireless video.