Multimedia Broadcast Multicast Service (MBMS) is a feature of the Third Generation Partnership Project's (3GPP's) LTE to support multicast transmission to multiple users in parallel, enabling more efficient utilization of network resources, e.g., for video broadcasting or common messages. MBMS is mostly considered in combination with Multimedia Broadcast Single Frequency Network (MBSFN), which further enables multicasting over multiple base stations, effectively forming a single frequency network. In this diploma thesis, efficient beamforming algorithms are devised for MBMS/MBSFN and their employment in vehicular communication, especially road safety applications, are investigated. These algorithms are intended to decrease the transmission latency of road safety messages thereby increasing the performance of data transmission within the MBSFN area and improving network utilization. The algorithms were implemented within an LTE compliant simulation framework. In the first chapter, an introduction to LTE MBSFN networks is given and basics of vehicular communication are shortly described. The aim of this chapter is to describe main architectural nodes introduced by MBSFN and provide insight into road safety applications. It is important to clarify which unique peculiarities experience road safety applications and how and why MBSFN can be used in these circumstances. Chapter 2 is devoted to an introduction of the basics of OFDM and the technique which allows to model Inter Carrier Interference (ICI). Networks with highly mobile terminals suffer from Doppler shifts, which could cause significant performance degradation. In order to simulate such effects commonly highly complex fast-fading simulations are performed. Due to complexity reasons fast-fading simulations usually are not an option in system level simulations. Nevertheless, in order to have precise modelling, these effects should be considered. In this chapter an efficient and precise technique to mimic fast-fading behaviour is explained and verification results are presented. In Chapter 3 the physical layer of MBSFN transmission is presented as well as additional mathematical techniques from the area of convex optimization. Additionally, the main performance metrics are explained, which are used to compare the efficiency of standard defined techniques to more advanced concepts introduced in this chapter. In Chapter 4 simulation results and achieved improvements are shown. The performance of the standard defined transmission in terms of latency and cell resource utilization are compared with results, obtained with algorithms described in previous chapters. Additionally possible gains of MBSFN networks in case of big number of multicast users are provided and explained. Finally Chapter 5 concludes the results, explains strong and weak parts of the proposed algorithm and sheds a light onto questions which require further investigation.
