Maximum A Posteriori Approach to Time-of-Arrival-Based Localization in Non-Line-of-Sight Environment

1517 Fig. 7. BER versus equivalent SNR performance of both perfect and imperfect relaying Ir-DST and noncooperative IRCC-URC-G2 schemes for a frame length of 250 000 bits, where the cooperative network is configured with Gsr = 8, G rd = 2, and Ls = Lr, and the noncooperative system is equipped with two transmit and four receive antennas. In this contribution, we have proposed an Ir-DST coding scheme for near-capacity cooperative communications. We have derived the CCMC capacity and the constrained information-rate bounds of Alamouti's G2 scheme for the half-duplex relay channel. The proposed joint source-and-relay mode design procedure is capable of finding the optimal Ir-DST coding scheme, which performs close to the capacity limit and achieves a maximum effective throughput. Furthermore, the code-design procedure is not limited to a specific networking scenario; it is applicable under virtually any network configuration. Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks, " IEEE Trans. Inf. On the achievable diversity-multiplexing tradeoff in half-duplex cooperative channels, " IEEE Trans. Distributed turbo trellis coded modulation for cooperative communications, " in Proc. ten Brink, " Designing iterative decoding schemes with the extrinsic information transfer chart, " AEU Int. A simple transmit diversity technique for wireless communications , " IEEE J. Unveiling near-capacity code design: The realization of Shannon's communication theory for MIMO channels, " in Near-capacity three-stage downlink iteratively decoded generalized layered space-time coding with low complexity , " in Abstract—A conventional approach to mobile positioning is to utilize the time-of-arrival (TOA) measurements between the mobile station (MS) and several receiving base stations (BSs). The TOA information defines a set of circular equations from which the MS position can be calculated with the known BS geometry. However, when the TOA measurements are obtained from the non-line-of-sight (NLOS) paths, the position estimation performance can be very unreliable. Assuming that the NLOS probability and distribution are known and the NLOS-induced error dominates the corresponding TOA measurement, two maximum a posteriori probability (MAP) algorithms for NLOS detection and MS localization are derived in this paper. The first provides a standard MAP solution, while the second is a simplified version based on geometric constraints. It is shown that the former achieves more accurate estimation performance at the expense of higher computational cost.