Since early experimentation in the late 1800’s, wireless communication has become increasingly important and has been widely adopted by civilian and military markets worldwide. The proliferation of wireless communication systems presents new challenges, threats and opportunities for society and government institutions. Although the possibility of infringing privacy laws exist, electronic survei...

In this thesis we investigate the worst-case performance of coded ordinary and coded generalized direct sequence spread spectrum (DSSS) systems in a communication channel corrupted by an unknown and arbitrary interfering signal of bounded power. We consider convolutional codes with Viterbi decoding in order to compare the performance of coded ordinary and coded generalized DSSS systems. For the...

Direct-sequence spread spectrum is popular for commercial wireless local-area networks, because license-free operation is permitted in certain frequency bands. The extensive development of equipment for such applications makes it attractive to investigate the use of the commercial technology for military communication networks. However, because of the small processing gain that is common in the...

Secure transmission of information over hostile wireless environments is desired by both military and civilian parties. Direct-sequence spread spectrum (DS-SS) is such a covert technique resistant to interference, interception and multipath fading. Identifying spread-spectrum signals or cracking DS-SS systems by an unintended receiver (or eavesdropper) without a priori knowledge is a challengin...

In this paper we present Walsh-quadrature phase-shift keying (Walsh-QPSK) pseudonoise (PN) modulation schemes for both coherent and noncoherent direct-sequence code-division multiple-access (DS-CDMA) systems, wherein the PN spreading sequences for in-phase and quadrature data in a conventional QPSK PN modulation scheme are coded by Walsh sequences indexed by a special rule to reduce the envelop...