Maximum likelihood detector

A maximum likelihood detector (ML detector) configured to execute a maximum likelihood detection (ML detection) according to one of a reception signal and a derivative thereof and according to one of a channel estimation signal and a derivative thereof, the ML detector comprising:

• a search value selecting circuit configured to determine a first-layer search value;
• and
• a maximum likelihood detecting circuit (ML detecting circuit) configured to execute at least the following steps:
• selecting K first-layer candidate signal values according to the first-layer search value, one of the reception signal and the derivative thereof, and one of the channel estimation signal and the derivative thereof, in which the K is an integer greater than one;
• determining whether to add Q first-layer candidate signal value(s) according to the K first-layer candidate signal values and thereby generating a first decision result, in which the Q is a positive integer;
• when the first decision result is affirmative, adding the Q first-layer candidate signal value(s), and calculating (K+Q) second-layer candidate signal values according to (K+Q) first-layer candidate signal values composed of the K and the Q first-layer candidate signal values;
• when the first decision result is affirmative, determining whether to add P second-layer candidate signal value(s) according to the (K+Q) second-layer candidate signal values and thereby generating a second decision result, in which the P is a positive integer;
• when the first and the second decision results are affirmative, adding the P second-layer candidate signal value(s), selecting P first-layer candidate signal value(s) according to the P second-layer candidate signal value(s), and calculating log likelihood ratios (LLRs) according to (K+Q+P) first-layer candidate signal values composed of the K, the Q and the P first-layer candidate signal values and according to (K+Q+P) second-layer candidate signal values composed of the (K+Q) the P second-layer candidate signal values;
• when the first decision result is affirmative and the second decision result is negative, calculating LLRs according to the (K+Q) first-layer candidate signal values and the (K+Q) second-layer candidate signal values;
• when the first decision result is negative, calculating K second-layer candidate signal values according the K first-layer candidate signal values;
• when the first decision result is negative, determining whether to add R second-layer candidate signal value(s) according to the K second-layer candidate signal values and thereby generating a third decision result, in which the R is a positive integer;
• when the first decision result is negative and the third decision result is affirmative, adding the R second-layer candidate signal value(s), selecting R first-layer candidate signal value(s) according to the R second-layer candidate signal value(s), and calculating LLRs according to (K+R) first-layer candidate signal values composed of the K and the R first-layer candidate signal values and according to (K+R) second-layer candidate signal values composed of the K and the R second-layer candidate signal values;
• and
• when the first and the third decision results are negative, calculating LLRs according to the K first-layer candidate signal values and the K second-layer candidate signal values.