Accession Number:

ADA426704

Title:

Interference Suppression in Multiple Access Communications Using M-Ary Phase Shift Keying Generated via Spectral Encoding

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT

Personal Author(s):

Report Date:

2004-03-01

Pagination or Media Count:

127.0

Abstract:

A conceptual transform domain communication system TDCS is shown capable of operating successfully using M-Ary phase shift keying MPSK data modulation in a multiple access environment. Using spectral encoding, the conceptual TDCS provides an effective means for mitigating interference affects while achieving multiple access communications. The use of transform domain processing with MPSK data modulation TD-MPSK provides higher spectral efficiency relative to other modulation techniques antipodal signaling and cyclic shift keying considered previously for TDCS applications. The proposed TD-MPSK technique uses spectral encoding for both data and multiple access phase modulations. Demodulation of the spectrally encoded TD-MPSK communication symbols is accomplished using conventional, multi-channel time domain correlation techniques. Analytic expressions for TD-MPSK probability of symbol error PE and probability of bit error PB are derived and validated using simulated results over the range of signal-to-noise ratios typically considered for communications. This validation includes scenarios with 1 multiple access interference, 2 spectral notching, 3 jamming present and 4 combinations of all three. For a JS of 3.14 dB and a EbN0 of 6 dB, PB dropped by up to a factor of 3 for TD-QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasnt present. The cross-correlation between communication symbols of different synchronous users can be made identically zero through proper selection of multiple access phase codes orthogonal signaling. For a synchronous network containing orthogonal users, PE and PB are unaffected as the number of orthogonal network users increases. For a JS of 3.14 dB and a EbN0 of 6 dB, PB dropped by a factor of 12 for TD-QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasnt present.

Subject Categories:

  • Cybernetics
  • Radiofrequency Wave Propagation
  • Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE