In this chapter we describe some fundamental concepts of LTE/SAE, elaborate on subsystems and functional components. We start with the radio access network and progress towards the core network, followed by additional network components (AAA infrastructure, policy and charging infrastructure, subscription and additional databases) and identity module in the terminal.
Obviously, the linear, sequential walk through these major components has some limitations; these have to play together, and the interfaces between them are common to the two corresponding sides. Some concepts anyway need to be spanned across several sub-parts of the system, and it is in the second part of this chapter where we elaborate on these (e.g. QoS, tracking, security, interworking in various variants).