Systematic performance comparison of narrow-band interference rejection algorithms for direct-sequence spread spectrum reception
Abstract
The capacity of Direct Sequence Spread-Spectrum (DSSS) modulation to reject narrow-band interference can be significantly improved by eliminating narrow-band energy at the receiver (frequency excision) using algorithms that operate on the Real Time Discrete Fourier Transform of the received signal (RT-DFT-Based). These algorithms have the potential to adapt very quickly to a changing interference spectrum and eliminate multiple tones, but to do this the decision of which frequency bins to excise must be made based on a very short observation time. Under these circumstances, the number of bins excised can be much larger than the number of bins containing narrow-band interference. The receive signal strength loss due to "over-excision" can be very significant and limits receive sensitivity. This work shows theoretical over-excision losses of several heuristic algorithms using a new analysis technique that accurately describes the performance of alternative non-linear time varying algorithms over a broad class of possible conditions. The sensitivity loss due to time weighting (or windowing) is presented for variable overlap and several different windows. These theoretical results are confirmed with simulation results and can be used to project sensitivity of PN spread spectrum systems that are located in a band that is also used by narrow-band systems. These results are instrumental in predicting the performance of systems which operate in the presence of multiple narrow-band interference, comparing the relative merits of alternative algorithms for arbitrary iterference spectrum, and determining hardware requirements necessary to support a given level of system performance.
Degree
Ph.D.
Advisors
Lehnert, Purdue University.
Subject Area
Electrical engineering
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