Davide Iacono

Experimental and Simulation Study of a WiMAX System in the Sea Port Scenario

The paper presents a measurement campaign carried out on a 2.5 GHz Mobile WiMAX test-bed in a sea port scenario, aimed at evaluating the system performance. The analysis of acquired data suggested the definition of a 2-ray pathloss model, which is able to fit the actual behavior of the observed marine channel. In order to evaluate the effects of the proposed pathloss model on system performance the paper presents a simulation study carried out by means of OPNET simulator. In particular, the simulation study is aimed at comparing the throughput at IP level obtained using different pathloss models implemented in OPNET, with that obtained when the proposed 2-ray model is considered. Further, the throughput at IP level obtained by simulation is compared with the one measured in the actual test-bed. This comparison points out that the WiMAX OPNET model is able to reproduce in most cases the system performance observed during the measurement campaign, when the proposed 2-ray pathloss model is used. However, the simulator is not able to predict the behavior of actual system in all situations. Indeed, in the areas where the pathloss presents peaks, the breakdown of system performance, mainly caused by synchronization problems, is not predicted by the simulator.

Notes on Implementing a IEEE 802.11s Mesh Point

Wireless Mesh Networks (WMNs) are gaining wide popularity as a flexible and cost-effective access technology. Many vendors and network operators have already deployed their own proprietary solutions, and, in the meantime, the IEEE has set off Task Group 802.11s (TGs) to develop a common standard for WMNs. So far, however, TGs has not yet produced a final document and is still working on the draft. In this context, we have built a prototype mesh node as much compliant as possible with the (still unofficial) 802.11s draft. A software framework was developed using common off-the-shelf technology and deployed on top of the legacy 802.11 interface card. We believe that the availability of such a prototype will permit to readily test the features and the amendments to the draft as soon as they are proposed, thus returning immediate and significant feedbacks on their effectiveness. This is an important milestone, as simulation trials, though very useful, often do not give answers on the actual feasibility of the tested feature. And, in fact, the prototype already allowed us to experimentally evaluate the basic 802.11s characteristics, pointing out some shortcomings and suggesting possible improvements.

WiMAX testbed for interconnection of mobile navy units in operational scenarios

The paper refers to the particular scenario where a set of naval units forms a WiMax-based mobile ad hoc network (MANET) to permit the communications among users on board of them and the sharing of the few satellite links towards the headquarter (HQ). In particular, the paper considers two different technical aspects: the definition of an appropriate architecture for the considered WiMax-based MANET adopting only Commercial off-the-Shelf (COTS) hardware and a performance evaluation campaign of the mobile WiMax communications in marine scenario. The performance was evaluated in terms of received signal strength, throughput at IP level, service availability, Quality of Experience of video services and VoIP calls. The measurement campaign was made on board of navy units, forming the WiMax-based MANET, in order to evaluate performance of such a technology in marine channel conditions. This is relevant considering the scarcity of experimental results on marine environment of Mobile WiMAX technologies.

Radio-Aware Scheduler for WiMAX Systems Based on Time-Utility Function and Game Theory

The paper presents a scheduling algorithm for WiMAX systems, which exploits Time-Utility Functions (TUFs) and game theory. The scheduling decision is performed by means of two steps: the intra-class scheduling step and the interclass scheduling step. In the first one, each user exploits TUFs to choice the packets to transmit according to QoS requirements. In the second one, the scheduler exploits the game theory to select a specific game solution that provides more or less fairness among the users that have to be served. The available physical network resources (i.e. slots) are taken into account as a constraint to the scheduling decision. The proposed scheduling algorithm follows a cross-layer approach that takes into account application requirements by means of TUFs and physical Channel State Information (CSI) of each user. Several game solutions are compared by means of simulation results in terms of user fairness, user throughput, packet delay and packet expiration rate. The TUFs introduction is also evaluated comparing the different applications performance.

Game theory and time utility functions for a radio aware scheduling algorithm for WiMAX networks

In WiMAX systems the Base Station scheduler plays a key role as it controls the sharing of the radio resources among the users. The goal of the scheduler is multiple: achieve fair usage of the resources, satisfy the QoS requirements of the users, maximize goodput, and minimize power consumption, and at the same time ensuring feasible algorithm complexity and system scalability. Since most of these goals are contrasting, scheduler designers usually focus their attention on optimizing one aspect only. In this scenario, we propose a scheduling algorithm (called

Experimental analysis of a WiMAX-satellite network for emergency management in sea areas

\mathrm{GTS_N}

On the WiMAX robustness against interfering signals in emergency marine scenario

) whose goal is to contemporaneously achieve efficiency and fairness, while also taking into account the QoS requirements and the channel state.