Improved Length Term Calculation and MMSE Extension for LISS MIMO Detection

List sequential (LISS) detection is an effective means of achieving near-capacity performance in iterative detection-decoding for MIMO systems. Using a length bias term calculated via an auxiliary stack has been shown to substantially narrow the tree search and thus reduce detection complexity. We present a novel approach to determine an approximation of the bias term, based on information available during the tree search in the main stack of the LISS detector. We also extend the LISS MIMO detector from ZF to MMSE based detection and show that by following this approach, a far better performance-complexity trade-off can be achieved.