Space-time coding in the third generation and beyond

We consider space-time coding and other techniques which have been developed to take advantage of the substantial capacity increases which are available in multi-antenna, or MIMO (multiple-in, multiple-out) radio channels. We address the question of how and to what extent these techniques may be exploited in third generation mobile systems based on standards such as UMTS. We consider both the dependence of the capacity on the radio environment, and the requirements of signal design for these channels. We show that the standard may be adapted to provide both capacity gains and diversity improvements, but care must be taken to ensure backward compatibility with handsets not designed for these signals. Multi-user detection is also important to provide a good signal to noise ratio