ts performance, and therefore the effects of receiver noise in the channel can be ignored. Thus, the performance results are generally based on the assumption that the jammer power is much larger than the noise in the receiver system. An exception to this is considered when we examine both non-uniform fading channels and multiple access channels where other user signals are taken into the analysis. 3.3 JAMMER WAVEFORMS There are an infinite number of possible jamming waveforms that could be considered. A class of jamming waveforms is selected to illustrate the basic spread-spectrum communication concepts and includes (to a good approx- imation) the worst types of jammer to the spread-spectrum systems of inter- est. There is no single jamming waveform that is worst for all spread-spectrum systems and t here is no single spread-spectrum system that is best against all jamming waveforms. For most of this work the following types of possible jammers are considered. 3.3.1 Broadband and Partial-Band Noise Jammers A broadband noise jammer spreads Gaussian noise of total power J evenly over the total frequency range of the spread bandwidth Wss as shown in Figure 3.2(a). This results in an equivalent single-sided noise power spectral density (3.8) Since the signal energy per bit is ST where =1/Rb, (3.9) Thus, in this case, the general definition (3.3) is exactly the bit energy-to-jam- mer noise ratio. The broadband noise jammer is a brute force jammer that does not exploit any knowledge of the anti-jam communication system except its spread bandwidth Wss. The resulting bit error probability of the anti-jam sys- tem is the same as that with additive white Gaussian noise of one-sided spec- tral density equal to N. We refer to the performance with this jammer as the baseline performance. In the following sections, we will illustrate how much worse the performance can become with other jamming waveforms of the same power J. Coding and interleaving, however, can be used to recover most of the performance loss as a result of th