Σχεδίαση προκωδικοποιητών (precoders) - αποκωδικοποιητών (decoders) για συστήματα ασύρματων επικοινωνιών πολλαπλών εισόδων - πολλαπλών εξόδων (MIMO)
Μανωλιουδάκη, Χαρίκλεια Ι.
The use of multiple antennas at the transmitter and receiver in wireless systems, popularly known as MIMO (Multiple-Input Multiple-Output) technology, has rapidly gained in popularity over the past decade due to its powerful performance-enhancing capabilities. MIMO systems provide the opportunity to increase the transmission rate linearly according to the lowest number of antennas (at the transmitter and the receiver). In addition, the MIMO techniques reinforce the reliability of the connection and enhance the coverage. MIMO systems are introduced in the next generation of mobile telephony and LAN wireless products promising that they will be adopted in the immediate future. In order to be able to benefit from MIMO systems only the receiver should know the communication channel or it is much better when the transmitter know the channel too. The value of transmit channel knowledge can be significant. For instance, in a four-transmit two-receive antenna system with independent distributed (i.i.d.) Rayleigh flat-fading, transmit channel knowledge can more that double the capacity at 5dB SNR and add 1.5b/s/Hz additional capacity of 5 dB SNR. The SNR ranges are common in practical systems such as Wi-Fi and Wimax applications. In a non-i.i.d. (independent and identically distributed) channel, the know of the transmitter channel offers greater leverage in performance. The evaluation of the information when the channel is known by the transmitter CSIT (Channel State Information) at the Transmitter has a great practical interest for the wireless MIMO systems.