A vehicular ad-hoc network (VANET) enables vehicles to communicate with each other directly or via roadside infrastructure in order to improve road safety and efficiency. Within a VANET, communications can potentially alter vehicular mobility and conversely, that the mobility could potentially influence vehicular communications. Therefore, a VANET simulator environment is needed that can accurately model interactions between vehicular mobility and network protocols. In this paper, we present a novel vehicular network simulation environment designed using the MATLAB discrete event system (DES) in the SimEvents toolbox. The proposed simulation environment is a bit-accurate, discrete event simulator that integrates vehicular mobility operations with wireless network communication. This paper provides details on the design of the proposed simulator. Its computational costs are evaluated in terms of events quantities and execution time. The physical (PHY) layer of the proposed simulator shows a more realistic packet success rate (PSR) using bit-level processing techniques when compared with the packet-based NS-3 simulator. The performance of the priority-based media access control (MAC) layer proves the data with different priorities that can coexist in the same channel.INDEX TERMS Vehicular network simulation, vehicular mobility models, discrete-event system.

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The number of GSM subscriptions worldwide reached 4 billion by the end of 2009 [1]. Voice is still one of the most important mobile services and its traffic continues to grow. In order to accommodate this growth, new voice enhancement concepts have continuously been developed for GSM. Both standardized and vendor-specific features have been developed to increase GSM networks' voice capacity. The Spectral Efficiency (SE) has improved many times since the introduction of GSM Phase 1 voice at the beginning of the 1990s. Performance has also improved, for example with more robust speech coding, advanced receivers and concepts allowing more users per channel. Moreover, Radio Resource Management (RRM) methods have been developed in order to optimize the available resources in changing traffic conditions and to fulfill the quality requirements of network operators. High capacity, spectral efficiency, cell coverage, low call drop rate, low blocking probability and high handover success rate are the basic requirements for a network to provide end users with a high quality voice service. In the past few years energy efficiency has also become an increasingly important aspect for network operators.In this chapter, a performance evaluation of GSM voice evolution is presented. The main focus is on the latest voice performance features, namely Orthogonal Sub-Channel (OSC), Voice over Adaptive Multi-user channels on One Slot (VAMOS), Adaptive Multi-Rate (AMR), Single Antenna Interference Cancellation (SAIC) and Downlink Advanced Receiver Performance (DARP). First, an overview of GSM voice evolution is given in Section 8.2. Then, the performance of AMR with SAIC/DARP is presented in Section 8.3. A detailed investigation GSM/EDGE: Evolution and PerformanceEdited by Mikko Säily, Guillaume Sébire and Eddie Riddington