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Show CHAPTER 1 INTRODUCTION A steady increase in the number of wireless communication systems being used for various purposes has led to an increasingly congested electromagnetic spectrum. Besides just the communication systems interfering with each other, we also have electromagnetic energy radiating from various electronic systems that we use everyday. With this constant increase in the interference, there is a great need for robust communication systems that can reject narrow band interference(NBI). In the coming years, there will be a growing necessity for communication systems that perform well in the presence of NBI. One of the effective ways of suppressing NBI is by using direct-sequence spread spectrum(DSSS) digital communication systems. When more than one user is attempting to share the same communication channel, we have a multiple-access communication system. Telephone systems and Ethernet are some of the most common examples. Some of the available techniques of 1nultiple-access communications are frequency-division multiple access(FDMA), time-division multiple access(TDMA) and code-division multiple"7access(CDMA). In code-division multiple-access communication, we have multiple users transmitting spread-spectrum waveforms. These waveforms have very little correlation between each other. This enables the signals to have very low interference with each other. Because of the spread-spectrum waveforms, we can have multiple users send out and receive signals at the same time on the channel and thus we have excellent channel usage in this type of communication. The receiver complexity in such systems depends on the decoding algorithm, and varies from simple to complex depending on the designer's choice. The designer might want to make the decoding algorithm very complex to prevent detection and increase security, or |
