A method and apparatus for increasing the capacity of a system that use four transmit antennas and that employs conventional channel coding by performing space-time coding in a particular way. Each of two pairs of symbol sub-streams is space-time coded to form a respective pair of transmit-sequence chains, where at least one of the formed pairs of the transmit-sequence chains is a function of symbols of the respective symbol-sub-stream pair and not a function of the symbols of the other symbol-sub-stream pair. Four transmit sequences--two transmit sequences from each of the two pairs of symbol sub-streams--may be viewed as forming a transmission matrices B or B' arranged as follows:.times..times..times..times..times..times..times. ##EQU00001## .function..times..times..times..times..times..times..times..times..times.- .times. ##EQU00001.2## .function..times. ##EQU00001.3## respectively, where b.sub.1, b.sub.2, b.sub.3, and b.sub.4 are the symbols derived from a respective one of four symbol sub-streams, and b*.sub.1, b*.sub.2, b*.sub.3, and b*.sub.4 are, respectively, the complex conjugate of the aforementioned symbols. The rows of the matrix represent the different antennas, while the columns represent different symbol periods.