QAM: the modulation scheme for future mobile radio communications?

With spectral congestion increasing, and plans announced to dramatically increase the number of mobile telephone users over the coming decade, many approaches are being considered to reduce the bandwidth requirements of each user. One approach is the use of quadrature amplitude modulation (QAM), a particular form of multilevel modulation where each symbol contains several bits of information. The use of QAM for mobile radio applications is considered and it is shown that this form of multilevel modulation can offer an attractive solution to current bandwidth restrictions in microcellular networks. An advanced variable-rate system is also considered and hardware development of a QAM modem discussed