Correlative Tracking of Pseudo-Noise Codes using a Phase Shifted Reference

This work investigates a first-order correlation loop for tracking pseudo-noise (PN) codes. The local reference is produced by a PN sequence generator in series with a Hilbert transform filter. The tracking performance of this non-linear loop is compared with conventional early-late delay-lock loops (ELDLL). Using a conservative definition of bandwidth, the new loop was found to be superior at moderate to low signal-to-noise ratios (SNR). Another advantage of the new structure is that it has a very large (arguably infinite) lock range

Performance analysis of a second order delay-lock loop with application to a CDMA system with multipath propagation

CDMA systems require synchronization between the received sequence and the locally generated sequence. This is done by means of a delay-lock loop (DLL). The differential equation of an incoherent second-order DLL has been programmed. The mean time to lose lock (MTLL) of the DLL is a very important design parameter. The authors have obtained this parameter by computer simulation and are able to plot the MTLL as a function of the signal to noise ratio in the data bandwidth. In a narrow-band system, the simulation shows that the effect of the fast Rayleigh fading is a performance degradation even with high mean signal to noise ratio. Assuming a wide-band system, so that the receiver has enough bandwidth to resolve the different propagation paths, the authors propose a modified DLL scheme. The MTLL of the proposed DLL is evaluated using a dynamic simulation of the multipath channel. The results show an improvement with respect to the conventional DLL.Peer ReviewedPostprint (published version

Code Acquisition at Low SINR in Spread Spectrum Communications

Abstract—We consider the problem of code acquisition at low signal to interference and noise ratio (SINR) in packet-based spread spectrum communications, where a centralized “pilot ” synchronization signal and high-precision oscillators are not available. Such problems arise in the context of ad-hoc networks, for example, which require fast code acquisition times and gradual degradation of the network with decreasing SINR. We motivate the use of the “postdetection integration ” ap-proach, which utilizes the energy of multiple bits in a packet, for code acquisition at low SINR. We present the implementation of a fully parallel architecture which simultaneously looks at all possible code alignments over multiple bits. This leads to a drastic reduction in acquisition time compared to serial search based methods. We report some preliminary simulation and experimental results from a hardware prototype of a transceiver on which the code acquisition algorithm was implemented. I

Adaptive systems in digital communication designs

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 98-100).by Xinben Garrison Qian.M.S

Millimeter communication propagation program, volume III Final report, 1 Nov. 1964 - 1 Nov. 1965

Annotated bibliography for millimeter wave communication propagation program for space-earth communication

Application of advanced on-board processing concepts to future satellite communications systems: Bibliography

Abstracts are presented of a literature survey of reports concerning the application of signal processing concepts. Approximately 300 references are included