The book describes the voice over LTE capabilities with a special focus on IMS and the signaling protocol SIP / SDP.
We will start with an overview on the IMS related architecture with special focus on the LTE Access network and 3GPP interworking with other RATs.
We will then introduce the bearer concept and QoS architecture in LTE / SAE discussing the signaling for default and dedicated bearer setup, e.g. IMS triggered with the interaction with the policy functions (PCRFs).
The purpose of the main architecture elements will be explained focusing in a sort of data sheet for each logical element. Other control entities,such as public, private and service identities, their relationsship and use will be explained in detail in order to understand service routing capabilities.
A central part will be an introduction to the signaling and media stream protocols, such as SIP / SDP, Diameter for policing and RTP / RTCP and their applicability for voice and other media transport in LTE.
This protocol section will be completed with a review of the softswitch architecture as required by LTE for a roaming environvironment with voice support, introducing the architecture and functionality of Media Gateway Controllers and associated Media Gateways.
We will then discuss in detail the alternatives for voice over LTE - with and without IMS support, such as SRVCC, CS Fallback and also quickly review other solutions such as VoLGA etc.
Related scenarios and different use case for SRVCC and CS Fallback - including SMS transmission - will then conclude the book.
Richard Huzenlaub