In this paper, we propose to use a new nonparametric noncoherent detector for PN code acquisition in DS/CDMA systems. Because this detector is nonparametric, we can decide the threshold of the detector without "rst having to estimate the variance of time-varying interference. We compare the single-dwell scheme using the proposed detector with that using the conventional detector. From the simul...

In this paper, a neural network based direct sequence spread spectrum code synchronization system is proposed. This system is based on training a recurrent random neural network (RNN) model on all the possible phases of the used spreading code. The trained network can then be used at the receiver for the initial coarse alignment of the local code phase and the received code. One advantage of th...

Code acquisition in CDMA systems is conventionally conducted with a matched-filter based structure. However, the performance of this method degrades greatly while multiple access interference presents. Recently, an adaptive filtering scheme was proposed to solve this problem. It has been shown that the computational complexity of this approach is proportional to the delay uncertainty and invers...

Satellite-based localization using the global positioning systems (GPS) has attracted ever growing attention in the last few years. In this work, we present a signal processing technique for initial code acquisition and synchronization of a GPS signal, such as the one used by position location techniques in 3G wireless scenarios. Several computer simulations have been accomplished to validate t...

ABSTRACT The performance characteristics of the cell averaging (CA), greatest of (GO), and smallest of (SO) constant false alarm rate (CFAR) processors in homogeneous environment are analyzed and compared when receiving antenna diversity is employed in the pseudonoise code acquisition of directsequence code division multiple access systems. From the simulation results, it is observed that the C...

CHIEVING and maintaining code synchronization between the transmitter and the receiver is critical to all spread spectrum systems hecause even a small ,,,isalignment can cause serious signal-to-noise ratio (SNR) degradation. VPically, this task is performed in two steps: code acquisition and trackng. Our focus here is to apply iterative meS. sage passing algorithms (MPAs), generalizations of th...

A noncoherent sequential P N code acquisition technique is proposed in this paper. Noncoherent detection is employed to handle the seriously noisy environments, while the carrier frequency offset and data modulation effects can be simultaneously taken care of. To realize the sequential acquisition, the out-of-phase and in-phase sequences are properly modeled to avoid the significantly high erro...

Modern military GPS receivers adopt a digital architecture to facilitate direct P(Y) code signal processing using high speed VHDL electronics. NAVSYS has developed a buffered digital receiver architecture that optimizes the GPS direct acquisition process by operating in the frequency domain. The effectiveness of acquisition in the frequency domain is dictated by the speed of the Fourier Transfo...

ABSTRACT A handshaking protocol for radiolocation is considered using DS-CDMA packet transmission. The expectation maximization (EM) algorithm is employed for code delay acquisition. It is shown that the systematic application of EM on the flat-fading channel yields a parallel interference cancellation (PIC)-based technique for acquisition. On the frequency-selective channel, it is necessary to...

In GNSS, longer integrations are required to obtain better signal-to-noise ratio during the signal synchronization process. However the presence of secondary codes on the top of primary codes puts a constraint on the coherent integration duration for pilot channels in a similar way to the effect of data bits in data-carrying channels. In this paper we explore the problem of coherent integration...