In a receiver of a wireless communication system, symbols in a single code block transmitted to a transmitter during a single Transmit Time Interval (TTI) experience different channels due to frequency selective fading of the channels. Accordingly, Post Processing Signal to Interference-plus-Noise Ratios (PPSINRs) of the symbols in the single code block have different values. An effective SINR indicating a reception quality for the single code block may be obtained by combining the PPSINRs of all of the symbols in the code block.
In general, methods for calculating an SINR of each symbol in a code block in a Single Input Single Output (SISO) system are explicitly defined. However, in a Multiple Input Multiple Output (MIMO) system, it is not as easy to calculate an SINR for each symbol because a signal received through a specific antenna contains an interference signal generated by a different antenna. In particular, since a Maximum Likelihood (ML) detector, which is used to improve performance at a MIMO receiver in currently, joint-detects the interference signal and thus does not treat the interference signal as a simple noise. Therefore, it is not easy to obtain an SINR for a symbol of a specific stream when the ML detector is used.
Accordingly, various related-art methods have been provided to obtain a link quality for each stream in an approximate method without calculating an SINR when a ML receiver for each symbol of a stream is used. For example, a method for measuring a link quality in a Minimum Mean Square Error (MMSE) detection method in a receiver using the ML detector has been provided. However, this method has a problem that the link quality is not exactly measured when a Signal to Noise Ratio (SNR) is high. That is, when the SNR is high, the PPSINR of each symbol in the code block is theoretically very low because power of the interference signal generated by the different antenna is operated as a noise. However, since the ML detector actually joint-detects the interference signal, the PPSINR of each symbol in the code block is high. Therefore, an error occurs in the result of measurement of the link quality when the MMSE detection method is used. Such a link quality measurement error may result in an error in channel status information feedback such as Channel Quality Indicator (CQI) feedback, Rank Indication (RI), or Precoding Matrix Indicator (PMI), and thus may cause grave deterioration in performance of a link throughput.
Therefore, there is a demand for a method for measuring a link quality without causing a measurement error or performance deterioration when an ML detector is used in a MIMO system
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.