This chapter is designed to give the reader a comprehensive understanding of the fundamentals in wireless protocol design. First, we overview some of the physical layer and the medium access control layer design choices. Then, we give the details of select major protocols as examples of the concepts described.

Physical layer

The physical layer has the main function of transporting the information bits passed by the higher layers over a physical medium and recovering them on the other side of the medium. We can view the physical layer in terms of a digital or analog communication channel and modules that map digital information to an analog signal in case the channel is analog. Figure 2.1 illustrates the main components of the physical layer that are discussed in the following sections. For an in-depth treatment of communication systems, the reader is referred to other texts.

Communication channel

A communication channel consists of a physical medium, such as radio waves, copper wire, optical fiber, and the associated equipment necessary to transmit information over the medium. Communication channels can be used for either digital or analog transmission. Digital transmission consists of transmitting a sequence of pulses corresponding to a sequence of information bits. Analog transmission involves the transmission of waveforms associated with the transmitted signal. The bandwidth of a channel, W, measures the width of the window of frequencies that are passed by the channel.