Generalized Differential Transmission for STBC Systems

Recent research has shown that differential transmission (DT) can be applied to STBC systems so that the receiver does not need channel state information (CSI) when compared to coherent detector. In this paper, we propose a generalized DT (GDT) scheme, which has a frame structure consisting of two parts, reference-block part and normal-block part. In contrast to the conventional DT (CDT) scheme, where each transmitted block is differentially encoded based on previous transmitted block, each GDT block in both of the two parts is differentially encoded based on previous reference block. It is shown that allocating more transmit power to the reference-block part leads to a more reliable reference for the differential detector. We discuss about the optimal power allocation between the reference-block part and the normal-block part. Simulation results show that the proposed GDT scheme achieves significant performance improvement over CDT and such performance can be very close to that of the coherent detection.