Linear and nonlinear precoding techniques for MIMO broadcast channel

Digital communication using Multiple-Input Multiple-Output (MIMO) has recently emerged, as one of the most significant technical breakthroughs in modern communications. The concept of MIMO systems is used extensively in currently deployed technologies to provide necessary data rates. In the multiuser, MIMO broadcast channel the benefits are enhanced when the transmitter knows the channel. Exploitation of such channel information allows for increasing the channel capacity, improving error performance while reducing hardware complexity. In order to detect the signal at the users terminals without any cooperation between them precoding techniques is required. This study describes the basics of various precoding techniques, examining both theoretical foundations and practical issues. Fundamental measures of the MIMO systems are the capacity and the error exponent, the practical measures are the Pair-wise Error Probability (PEP), Mean Square-Error (MSE), Symbol Error Rate (SER), Bit Error Rate (BER) and the received SNR. A brief comparison is done between the performances of the system with and without precoder, various linear and nonlinear precoding techniques by analyzing the ergodic capacity and BER.