Near-ML detection based on semi-definite programming for UWB communications

Recently, multi-symbol based transmitted reference system has drawn attention for UWB communications because of its high performance without estimating the channel explicitly. The maximum-likelihood (ML) detector for multi-symbol transmitted reference system has been proposed to jointly detect the multi-symbol and yields a considerable improvement compared with conventional single symbol detector. However, the high computational complexity incurred by ML detectors hinders their applications to practical systems. In this paper, we propose a polynomial-time (in worse case) approximation near-ML detector based on semi-definite programming (SDP). Simulation results demonstrate that the proposed SDP detector provides almost the same BER performance as the ML detectors and is robust to the multi-access interference.