A very promising approach for various wireless applications is to use multiple antennas at both transmitter and receiver. The error rate performance and complexity of the algorithms are evaluated for different antenna configurations, for various constellation sizes, for different channel properties with and without coding. It is shown that Maximum Likelihood Detection (MLD) outperforms the other schemes. Its complexity, however, is the highest and growing exponentially with the number of transmits antenna. Less complex alternatives are found that have only a slightly worse performance. Since Vertical Bell-Labs lAyered Space-Time (V-BLAST) techniques are simulated.