LTE and the Evolution to 4G Wireless: Design and Measurement Challenges, 2nd Edition

6.11 Signaling Protocol Development and Testing

6.11.1 Introduction

Given the complexity of the LTE UE, successful products rely on a program of testing that goes beyond the requirements of the standards. As part of that program, the stability of the software in the UE needs to be the subject of relentless and systematic test. That includes the signaling software, which is a major contributor to the overall stability of the UE.

This section discusses the challenges associated with developing the UE signaling protocols and describes a test environment in which engineers can write and execute test applications.

6.11.2 Challenges of UE Signaling Protocol Development

6.11.2.1 Development Complexity

By necessity the LTE UE supports many signaling protocols to enable communication (1) with the base station (eNB) for the air interface connection and (2) with the evolved packet core network. In many cases protocols are replicated to accommodate multiple radio access technologies (RATs) such as GERAN, UTRAN, cdma2000, and LTE E-UTRAN. In addition, protocols must be developed to interact with the core network and the application entities that make the UE’s location known to the network, and to manage the packet-switched and circuit-switched connections along with the associated services and subscriber applications. The complexities faced by protocol stack developers are evident. When a new technology feature is added to the UE, whether specific to a RAT or spanning multiple RATs, the new ...