Fundamentals of Wireless Communication Engineering Technologies

Chapter 7

Component Technologies

In this chapter we examine some component technologies that are part of wireless access. These technologies are typically needed to meet various requirements of the wireless access subsystem. For example, the wireless medium is a shared medium, so medium access control schemes are needed, and we cannot simply reuse wireline medium access schemes, as discussed in Section 7.1. In cellular-type wireless systems, the ability to move users from cell to cell in an efficient and timely way is a critical part of the cellular idea. We explore this in Section 7.2. In wireless access systems, interference control is very important, and one of the ways of controlling the amount of interference that any transmission causes to others is by controlling the transmit power levels, as discussed in Section 7.3. In section 7.4 we examine error control coding, which is especially crucial for wireless access since the raw error rates are higher than with wired communications.

7.1 Medium Access Control

At a fundamental level, the wireless medium is a shared resource. If we examine a system and it appears that a particular wireless link is the exclusive property of a particular transmitter–receiver pair, with no interference from other transmitters, this can only be because something is happening at a lower layer to give it such an appearance. For example, a mobile phone application might be written as if it has an exclusive or dedicated link to a library of ebooks on ...