With the commence of the IMT-Advanced (IMT-A) submission and evaluation process, the vague term "4th generation wireless networks" moves towards existing standards, technologies and hardware. A significant part of the evaluation process is based on the system level simulation of reference scenarios.In this paper, we present how the open Wireless Network Simulator (openWNS), developed in the last 5 years at the department of Communication Networks (ComNets) at RWTH Aachen University, can be used to study protocols of wireless networks. Due to the complexity of IMT-A candidate systems, the features of openWNS are described by means of the lightweight WiFiMAC. This module provides the functions of IEEE 802.11, including amendment n.On this basis, the following details of the simulator are explained: (a) the modular simulation framework for protocol stack development, (b) the WiFiMAC module, (c) simulator calibration to ensure the reliability of the results and (d) the simulation of urban-micro scenarios based on the IMT-A evaluation guidelines.

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The Ambient Networks project develops a complete and coherent solution for control architectures in future networks. In particular, the concept of Ambient Control Space has been proposed to support a technology-agnostic, modular and dynamic control plane. The second phase of the project (2006)(2007) has an increased focus on validation, where two complementary tracks are being followed: proof-ofconcept prototyping and performance evaluation through simulations. The prototype modules, focusing on requirement engineering, were validated during the process of integrating them into a common control space prototype, which was later used to build the demonstration setups. The system performance evaluation through simulations deals with aspects such as capacity utilization, reachability, cost and performance trade-offs and also provides evidence that the additional AN features (e.g., composition) do not introduce excessive signaling overhead. We target different composition aspects, advertising & discovery, negotiation of composition agreements and their interaction with multi-radio access and mobility control. Our validation approach is based on several use cases.