Signals are developed for use in a wireless system with multiple transmit
and multiple receive antennas so that even in the face of some correlation
the most open-loop capacity that can be achieved using a substantially
open-loop system with a channel of that level of correlation is obtained.
In accordance with the principles of the invention, the signals
transmitted from the various antennas are processed so as to improve their
ability to convey the maximum amount of information. More specifically,
the data to be transmitted is divided into M+1 substreams, where M is the
number of transmit antennas. Each transmit antenna is supplied with a
combination signal that is made up of a weighted version of a common one
of the substreams and a weighted version of a respective one of the
substreams that is supplied uniquely for that antenna, so that there are M
transmit signals. A receiver having N antennas receives the M transmit
signals as combined by the channel and reconstitutes the original data
therefrom. This may be achieved using successive decoding techniques.
Advantageously, the capacity, i.e., the rate of information that can be
conveyed with an arbitrarily small probability of error when the
instantaneous forward channel condition is unknown to the transmitter, is
maximized.
