As we said at the end of Chapter 1, CDMA is applicable to digital (as opposed to analog) communication. This chapter is therefore devoted to providing an overview of basic digital communication. In its bare essence, digital communication consists of transmitting binary digits (1's and 0's) over a channel to a receiver. This process requires associating 1's and 0's with unique waveforms since the physical means of transmitting information over a wireless channel is through the conversion of information bearing waveforms into EM waves. There are also issues such as data transmission rate, noise, and modulation. These issues are addressed in this chapter beginning with the formation of the transmission waveform. The effect of noise is dealt with next, followed by that of bandwidth. The chapter concludes by looking at elementary digital modulation techniques.
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