| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 89 === The purpose of most spread-spectrum systems is to transfer information from one place to another. One figure of merit for these systems is the probability of correctly communicating a message in a particular noise and/or jamming environment. The original purpose of spread-spectrum technology is to military and space communications systems. Although the application to the military and space communications remains extremely important, current research in spread-spectrum communications is focused on the application of spread-spectrum techniques to multiple-access communications. In particular, spread-spectrum technology is now being applied to cellular telephony, where it will provide significant increase in the number of users that can be supported in a given bandwidth. The channel and interference models for the application of spread-spectrum technology to cellular telephony are very different from those discussed in this thesis.
In the conventional jamming strategies, the gain of the channel is assumed to be constant and time invariant across the entire transmission band, whereas the channel for cellular telephony is a time-varying fading channel. And the interference assumed in conventional jamming environment is, for the most part, hostile, whereas the source of interference in cellular telephony is other users of the system. In this thesis, we concentrate our attention to the hostile jamming environment, but the time-varying interference is considered. In the Chapter 1, we introduce some famous jamming environment and discuss the advantages and disadvantages among them. After that, we hope to find out a trade-off between partial-band jamming and multiple-tone jamming. This will be done in Chapter 2 and 3. Then a conclusion is given in Chapter 4. We will obtain a jamming strategy that is more feasible than multiple-tone jamming and is more destructive than partial-band-jamming.
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