Efficient Channel State Information (CSI) Feedback for Close-loop MIMO-OFDM Systems

• Main Authors: Wei-TingChen, 陳維廷
• Other Authors: Ming-Xian Chang
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/29391258237328304033

碩士 === 國立成功大學 === 電腦與通信工程研究所 === 102 === Multiple antennas -multiple carriers systems have been attracted many attention for a long time due to the outstanding capacity, error performance and throughput. The transmitter could apply the precoding based on the fed-back channel state information (CSI). The beam forming vectors, which are essential CSI, could be applied in precoded multiple-input multiple-output (MIMO) systems and some algorithms of CSI reduction and efficient feedback have been proposed. However, the power allocation, antenna selection and multi-mode precoding which can be applied in precoder are also important issues for increasing the channel capacity and improving the transmission performance. In general, we can use the vector quantization to feed back the beam-forming vectors to the transmitter. To implement a precoder which can be used not only the beam-forming but also the power allocation, we need to feed-back other channel information. In order to feed-back CSI more efficiently, we propose an efficient method that feed-back the estimated channel responses (CRs) to the transmitter based on the Karhunen-Loève Expansion (KLE). The coefficients of the KLE are used as the parameters for rebuilding CRs. The number of coefficients of the KLE is much fewer than the size of than the block of CRs, and this leads to efficient compression. These coefficients are of Gaussian distribution. To efficiently return the coefficients for the MIMO with orthogonal frequency-division multiplexing (OFDM) systems, we use the Gaussian quantization (GQ) to reduce quantization error. The simulated results show that the proposed algorithms could attain outstanding error performance for precoded MIMO-OFDM systems with low feedback load in the time-varying and frequency-selective channel.