RSTD Performance for Small Bandwidth of OTDOA Positioning in 3GPP LTE

We studies the influence of multiple reference signals on different transmit ports for RSTD measurements in small bandwidth scenarios. Because of scalable measurement bandwidth in long term evolution (LTE), the performance of reference signal time difference (RSTD) suffers from small bandwidth. Conventional RSTD scheme is based on positioning reference signals (PRS) which use one transmit antenna and two receive antennas (1x2). In order to reduce the loss of accuracy caused by small bandwidth, three new schemes are proposed. Compared with the conventional scheme, the accuracy of three proposed schemes has been improved in ETU channel. We verify it with our simulation results. The detection probability of one proposal 2x2 scheme which splits PRS symbols on two transmit antennas is decreased by half the number of accumulating symbols on each transmit antenna. Other two schemes which accumulate cell-specific reference signals (CRS) and PRS non-coherently or coherently not only provide better RSTD accuracies but also improve detection probabilities.