There are two aspects to mobile communications: mobile network access and mobility management, which are depicted in Figure 1.5. In this book we will address both of these aspects in the context of mobile data communications, as well as other issues which, although less centric to mobility, are important to any "real world" business.
The first aspect of mobility is accessing or connecting to the communications network. This network access is media-specific and might involve using a pay phone, plugging a 10BASE-T jack into a wall socket or powering-up a wireless device within an appropriate coverage area. We discuss network access for CDPD systems in Chapter 5.
Because mobile network access is a big issue, previous books on mobile data communications have tended to focus on it. But "getting connected" is only half of the battle.
The second aspect of mobile communications is the ability to efficiently send and receive communications from wherever you are, once you have accessed the network. This is called mobility management or location management. Somehow the rest of the world must be able to reach you wherever you are. This is the essential challenge of mobile communications and the manner in which this challenge is addressed has broad implications on mobile data applications.