In this paper we extend hyperparameter-free sparse signal reconstruction approaches to permit the high-resolution time delay estimation of spread spectrum signals and demonstrate their feasibility in terms of both performance and computation complexity by applying them to the ISO/IEC 24730-2.1 real-time locating system (RTLS). Numerical examples show that the sparse asymptotic minimum variance (SAMV) approach outperforms other sparse algorithms and multiple signal classification (MUSIC) regardless of the signal correlation, especially in the case where the incoming signals are closely spaced within a Rayleigh resolution limit. The performance difference among the hyperparameter-free approaches decreases significantly as the signals become more widely separated. SAMV is sometimes strongly influenced by the noise correlation, but the degrading effect of the correlated noise can be mitigated through the noise-whitening process. The computation complexity of SAMV can be feasible for practical system use by setting the power update threshold and the grid size properly, and/or via parallel implementations.

We analyze the performance of an adaptive hybrid search code acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems under slowly-moving mobile environments. The code acquisition algorithm is designed to provide the desired feature of constant false alarm rate (CFAR) to cope with nonstationarity of interference in CDMA forward links. An analytical expression for the mean acquisition time is first derived and the probabilities of detection, miss, and false alarm are then obtained for frequency-selective Rayleigh fading environments. The fading envelope of a received signal is assumed to be constant over the duration of post-detection integration (PDI), which is most reasonable, especially for slowly-moving mobile environments. The performance of the designed code acquisition algorithm shall be evaluated numerically to examine the effect of some design parameters, such as the sub-window size, the size of the PDI, the decision thresholds in search and verification modes, and so on, considering IMT-2000 environments.

This paper considers the evaluation of the acquisition performance for an access channel preamble based on the random access procedure of direct sequence code division multiple access (DS/CDMA) reverse link. The parallel acquisition technique that employs the single-dwell and multiple-dwell (double-dwell) detection schemes is investigated. The acquisition performance for two detection schemes is compared in terms of the acquisition probablity and the mean acquisition time. The parallel acquisition is done by a bank of N parallel I/Q noncoherent correlators. Expressions on the detection, false alarm, and miss probabilities of the single-dwell and multiple-dwell (double-dwell) detection schemes are derived for the multiple H1 cells and multipath Rayleigh fading channel. Comparing the single-dwell detection scheme with the multiple-dwell (double-dwell) detection scheme in the case of employing the parallel acquisition technique in the reverse link, the numerical results show that the single-dwell detection scheme provides a better performance.

In this letter we propose an adaptive beamforming algorithm that efficiently suppresses interferences using a structured interference covariance matrix. The proposed algorithm provides high performance by exploiting angle diversity, especially in cellular mobile environments where the angular spread of a received signal is relatively small. We verify the superiority of the proposed algorithm to the well known linearly constrained minimum variance (LCMV) and reference signal-based algorithms.