Multicarrier Transmission for Wireless Location --- Range Estimation and Positioning

This thesis deals with wireless location using non-data-bearing (NDB) multicarrier (MC) transmission, for range estimation and positioning. Time-based range estimation (TBRE) using orthogonal frequency-division multiplexing 1 (OFDM) transmission is investigated, both theoretically, in terms of its Cramer-Rao lower bound (CRLB), and practically, in terms of its maximum likelihood estimator (MLE). Its CRLB achieves a 4.8dB signal-to-noise-ratio (SNR) improvement over its pseudo-random noise (PN) counterpart in both time-invariant channels and time-varying channels. Its MLE for TBRE is proven to outperform its MLE for channel estimation (CE) except in a separable multipath channel where they perform equally. The MLE for TBRE in a multipath Doppler channel is developed with respect to the separability of its multipath components, where the condition for a multipath Doppler channel to be separable is explored for a MC signal as well as for a PN signal. In the threshold region, the probability of outlier and the resulting mean square error (MSE) are theoretically derived based on the MLE for TBRE. Furthermore, the optimal subcarrier selection (OSS) is proposed for MC transmission by minimizing its CRLB, which exhibits a 4.8dB SNR improvement over its OFDM counterpart, and a 9.6dB SNR improvement over its PN counterpart. The OSS is proven to be a truncated cosine signal, which is more robust against carrier frequency offset (CFO), multipath-Doppler shift (MDS) and narrowband interference (NBI) than its OFDM counterpart. To increase its maximum ranging distance (MRD), a sub-optimal subcarrier selection (SOSS) is proposed based on a constrained optimization process.;1OFDM transmission is regarded as a special case of MC transmission throughout this thesis.;Using a uniform subcarrier arrangement, a substitution for the global positioning system (GPS)-based coarse/acquisition (C/A) code is proposed. The proposed substitution provides a 4.73dB SNR improvement in terms of its CRLB over the current PN-based C/A code, while exhibiting robustness against NBI. The Doppler shift for an MC-based receiver is also explored and the probability of collision (POC) between satellites due to Doppler shift is theoretically analyzed. Finally, we propose to use MC transmission and one of two novel Round-Trip-Delay (RTD)-based positioning protocols in OFDM-based 4G cellular networks such as in worldwide interoperability for microwave access (WiMAX): one protocol is designed for an MS-managed solution while the other protocol is designed for a network-managed solution. Theoretical analysis is also provided to assess the performance of our proposed positioning protocols and to show that they have a better positioning accuracy than either a range-based positioning protocol or a range difference positioning protocol with respect to their corresponding CRLB and best linear unbiased estimator (BLUE).