Receiving apparatus and method for mimo system

A receiving apparatus of a multiple input and multiple output (MIMO) system, comprising:

• a QR decomposing means for calculating a single (Q) matrix vector and an upper triangle (R) matrix vector for a receiving signal vector;
• a first detection means for linearly estimating predetermined symbols using the calculated Q matrix vector and the R matrix vector and calculates a log likelihood ratio (LLR) in a bit unit for the estimated symbols;
• a second detection means for receiving a signal decoded for the detected symbols, removing interference from the receiving signal vector, and linearly estimating remaining symbols for the interference removed signal;
• and
• a decoding means for decoding the detected symbols from the first detection means, providing a decoding signal for the predetermined symbols to the second detection means, and decoding the detected remaining symbols from the second detection means.

A receiving method of a multiple input and multiple output (MIMO) system, comprising:

• calculating a single (Q) matrix vector and an upper triangle (R) matrix vector for a receiving signal vector;
• estimating predetermined symbols using the calculated Q matrix vector and R matrix vector;
• calculating log likelihood ratios of unit bits for the estimated symbols;
• receiving a decoded signal that is decided using the calculated log likelihood ratios and removing interference from the receiving signal vector;
• and
• linearly estimating remaining symbols for the interference removed signal.