A Simple Polarization - Forward Mimo Relay Encoding

In MIMO (multiple-input multiple-output) wireless communication systems, transmitters and receivers are equipped with multiple antenna units for data transferring process. Compared with SISO (single-input single-output) wireless communication systems, additional degrees of freedom (Space resource) can be created in MIMO system without increasing neither the transmit power nor bandwidth, which can be exploited for significant improvement of system capacity and enhancement of transmission reliability. Thus, MIMO has been extensively studied as the key technology of the fourth generation mobile communication system(4G).Motivated by Arikan’s channel polarization approach that shows the occurrence of capacity-achieving code sequences, the coding design issues are addressed by switching to polarizing MIMO relay channels while transmitting information symbols in a source-relay-destination communication system. A simple polar-and-forward (PF) MIMO relay scheme, with source node polar coding and relay nodes polar coding, is proposed to provide an alternative solution for transmitting with higher reliability than the conventional decode-and-forward and amplify-and-forward (DF/AF) relay schemes. The present PF MIMO relay system is divided into two symmetrical polarizing relay systems,i.e.,the down-polarizing system and the up-polarizing system,which result in different capacities for the polar MIMO relay channels.The bit error rate (BER) performance is analyzed with the fixed polar MIMO relay system equipped with four transmit antennas, which is an idea approach to select signal sequences that tend to polarize in terms of the reliability under certain combining and splitting MIMO relay channels. The polar MIMO relay system has a salient recursiveness feature, and thus the transmitted information signals embedded in the stacked Alamouti code and the equivalent Jafarkhani code can be decoded with a low-complexity decoder.An attempt is made to meet this elusive goal for the MIMO relay channels motivated by the fascinating Shannon’s channel coding theorem in this thesis. It is an extension of work where channel combining and splitting are used for recursive code construction and successive cancellation decoding, which are two essential characters of the polar coding sequences. This is an idea approach to construct code sequences as combining and splitting MIMO relay wireless channels to increase its reliability. Furthermore, an analytical framework that illustrates the potential bit error rate (BER) performance is established to be achieved from the polar MIMO relay system. The present system may increase the symmetric capacity under a low computation complexity of the successive cancellation decoding due to the fact that a large number antennas may be equipped for the polarizing MIMO relay channels that tend to polarize under certain channel combining and splitting operations.