nterference in the channel is due to L other radio transmitters of power Jill=1,2, , L (2.1) Spread-Spectrum Multiple Access with DS/BPSK Waveforms at the receiver in question while the intended signal has power S. Then the effective bit energy-to-jammer-noise ratio is (2.2) where PG = N (2.3) is the number of chips per data bit and (2.4) As an example suppose the K = 7 rate R=1/2 convolutional code with soft decision Viterbi decoding is used with the DS/BPSK waveform. To achieve 10-6 bit error probability we require the bit energy-to-noise ratio of (see Figure 1.7 of Chapter 1 in Part 2) Eg/N = 5 dB. (2.5) Also suppose the number of chips per data bit is N = 1000 =30 dB. (2.6) This means the point-to-point DS/BPSK radio link in question can com- municate effectively as long as the total interference power satisfies (2.7) That is, up to 316 radios of equivalent power (at the receiver) as the intended transmitter signal can be simultaneously transmitting DS/BPSK waveforms. In practice, of course, some radios will be closer6 than others and the power levels will be unequal at the receiver. This is the "near-far" problem encoun- tered in terrestrial radio networks. Also some of the interference may be due to multipath components of the intended signal. In this example all these interferences must have total power that is no more than 316 times the intended signal power at the receiver. The analysis here is based on the continuous jammer of power J. In a radio network, interference in any point-to-point link will vary randomly in time. Here assume the maximum interference power is less than the prescribed value. In general a coded or uncoded spread-spectrum DS/BPSK system designed to combat continuous jamming will have the same performance bound (see Section 1.2, Chapter 1, Part 2) as a BPSK signal in white 6f an interfering radio is very close it can drive the receiver front end to saturation and effec- tively block all transmissions. The analysis here assumes no saturation has taken place. Multiple Access Gaussian 