Area Efficient Pipelined VLSI Implementation of List Sphere Decoder

Since finding the nearest point in a lattice for multi-input multi-output (MIMO) channels is NP-hard, simplified algorithms such as sphere decoder (SD) have been proposed. List sphere decoder (LSD), which is a modified version of SD, allows soft information to be extracted for channel decoding and iterative detection/decoding. In this paper, recently proposed efficient methods for reducing the computational complexity of SD and LSD with depth-first tree searching are summarized. Based on theses methods, VLSI implementation with an efficient pipelined architecture for LSD with real-valued operation for area efficiency is also presented