Novel link adaptation for TETRA cellular systems

One of the main challenges for future wireless systems is to enhance the effective data throughput by exploiting the allocated bandwidth as much as possible. Among several approaches at different layers, one of the most important is constituted by the so‐called link adaptation (LA) techniques. They are characterized by the adaptation of a set of transmission parameters to the channel state in order to improve performance. In this context, this paper is focused on the analysis of a particular class of LA techniques called adaptive modulation and coding, where the modulation and coding rate of transmission can vary according to the channel behavior. In particular, a novel LA algorithm, namely the timed window (TW) method, suitable for time‐division Duplex systems is proposed here. The performance of the TW algorithm is evaluated by taking actual user mobility conditions, communication channel behavior, as well as the physical layer effects into account. Finally, it is important to stress that, even if the wireless bearer considered in this study is TETRA (TErrestrial Trunked RAdio), the approach is quite general and it can be of interest for other wireless networks and can be optimized for different channel models (e.g. TU50, HT200, etc.). Copyright © 2008 John Wiley & Sons, Ltd.     

Generation of digital terrain models with a ground-based SAR system

A novel technique for the retrieval of a digital terrain model (DTM) with a ground-based synthetic aperture radar (GB-SAR) system is described. A set of SAR images collected over a test site located at Salice d'Ulzio, Italy, is used to validate experimentally the proposed DTM retrieval technique. The topographic height is obtained using an algorithm specifically tailored for a GB-SAR system equipped with two receive antennas. The comparison with an existing DTM of the test site area shows that the retrieved DTM is accurate, with root mean square height differences between the two DTMs below 5 m.     

Ground-based SAR interferometry for terrain mapping: theory and sensitivity analysis

This short communication studies the problem of terrain mapping by means of the ground-based synthetic aperture radar (GB-SAR) interferometry technique. A phase-to-height relationship tailored for the GB-SAR interferometric configuration is introduced and verified by a simulated analysis. A sensitivity study is carried out aiming to optimize the use of a GB-SAR system for the terrain mapping and to derive the precision of this technique.     

Analysis and comparison of scheduling techniques for a BWA OFDMA mobile system

In the last few years the wireless metropolitan area networks (WMANs) have increased their popularity and attracted the interest of important research groups all over the world; as a consequence, several standards have been proposed. Among them, the IEEE 802.16 (WiMAX) is one of the most promising standard to carry out a full‐service broadband wireless network in an urban and suburban area. This standard provides high data rate within a wide coverage area with low implementation costs, possibility of multi‐traffic communications, and different network topologies. This paper deals with the analysis and performance comparison of different scheduling techniques for WiMAX networks for allowing quality of service (QoS) differentiation when different types of applications have to be supported and achieving a fair distribution of resource among users. In particular, the focus here is on the resource allocation problem for the case of mobile stations (MSs) active in an urban environment. The proposed scheduling algorithms exploit the orthogonal frequency division multiple access (OFDMA) scheme with adaptive modulation techniques in order to achieve a better network behavior. The performance of the proposed approaches will be derived here by means of theoretical analysis and computer simulations. Copyright © 2009 John Wiley & Sons, Ltd.     

Proposal of a Fixed Communication System Sharing the Bandwidth of an Existing Personal Communication Network

This paper deals with the proposal and performance evaluation of a fixed microwave communication (FMC) system that shares the same bandwidth with a wireless personal communication network. In particular, the focus here is on the case of an existing universal mobile telecommunication system (UMTS) network for which an FMC system is considered to provide a wireless connection between a remote base station not having the possibility of a wired connection to the core network and a base station having this possibility (a core network access point). This facility is of special interest in a dense urban environment or whenever a wired connection is prohibitive for service providers due to its implementation cost or lack of frequency spectrum. The mutual interference effects between the FMC systems and the existing UMTSs are investigated by focusing on typical application scenarios. A receiving scheme where interference signals are first detected and then canceled from the other received signals is proposed. The performance of the two interfering systems has been evaluated in terms of bit error rates (BERs) both by means of an analytical approach and computer simulations. The obtained results clearly demonstrate the effectiveness of the proposed method, in particular, by allowing efficient bandwidth sharing between the FMC system and the existing UMTS network.     

QoS provisioning in GEO satellite with onboard processing using predictor algorithms

Recently, IP satellite networks have attracted considerable interest as a technology to deliver high-bandwidth IP-based multimedia services to nationwide areas. In particular, IP satellite networks seem to be one of the most promising technologies for connecting users in rural areas, where a wired high-speed network (e.g., xDSL) is not foreseen to be used. However, one of the main problems arising here is to guarantee specific quality of service constraints in order to have good performance for each traffic class. Among various QoS approaches used in the Internet, recently the DiffServ technique has become the most promising solution, mainly for its scalability with respect to the IntServ approach. Moreover, in satellite communication systems, DiffServ computational capabilities are placed at the edge points, reducing the implementation complexity of the satellite onboard equipment. This article deals with the problem of QoS provisioning for packet traffic by considering some resource allocation schemes, including bandwidth allocation techniques and priority-driven onboard switching algorithms. As to the first aim, the proposed technique takes advantage of proper statistical traffic modeling to predict future bandwidth requests. This approach takes into consideration DiffServ-based traffic management to guarantee QoS priority among different users. Moreover, the satellite onboard switching problem has been addressed by considering a suitable implementation of the DiffServ policy based on a cellular neural network.     

Perspectives for present and future CDMA-based communications systems

In this article the main boosters of future CDMA communication systems are presented and described in order to highlight the ways to cope with the more challenging requirements of future systems and services. Particular attention is devoted to the inherent weak points of CDMA systems and detection techniques that can be used to overcome their impairments. Moreover, high-data-rate transmissions in wireless channels require proper link adaptation techniques; these are thoroughly described as well. Finally, the last part of this article focuses on the design of suitable protocol strategies for new heterogeneous multimedia packet services characterized by strict QoS requirements     

Structural static testing by interferometric synthetic radar

In this paper, the authors propose a radar technique for building structural static testing or monitoring. The technique is based on interferometric step-frequency continuous-wave (SFCW) radar. It works synthesising microwave holographic images, and comparing pairs of holograms to obtain a deformation map. The application of the interferometric technique for structural static testing of a concrete pedestrian bridge is described. The radar-measured deformation profile has been compared with a finite element simulation of the bridge.     

A channel state‐driven ACM algorithm for mobile satellite communications

The last decade has been characterized by an increasing demand of higher throughput and more reliable communication links for supporting multimedia applications. To this aim, the focus has been toward both broadband and broadcast solutions providing multimedia services to mobile users. In order to exploit such advanced services, ubiquitous and efficient mobile connections are required: satellite communications (SatCom), able to cover low density populated areas and to fill terrestrial coverage gaps, are a viable solution, as long as capacity is properly optimized. Waveform adaptation can be considered as one of the reference approaches for increasing the throughput and the reliability in wireless communication links. However, the large round trip time and user mobility in SatCom scenarios represent a serious challenge that limits the effectiveness of transmission parameters adaptation. In this paper, we focus on a novel state‐driven adaptive coding and modulation approach aiming to predict the most suitable modulation and coding scheme for each communication state, based on channel state estimation and a Markov propagation model. The paper introduces the concept of state estimation decision reliability and transmission reliability. Different from other approaches, the state‐driven algorithm allows to increase the system reliability by lowering the outage probability in the selected scenarios. The effectiveness of the proposed approach has been validated by resorting to numerical results after a careful parameter optimization. Copyright © 2015 John Wiley & Sons, Ltd.     

Reactions with Proteins of Three Novel Anticancer Platinum(II) Complexes Bearing N-Heterocyclic Ligands

Three novel platinum(II) complexes bearing N-heterocyclic ligands, i.e., Pt2c, Pt-IV and Pt-VIII, were previously prepared and characterized. They manifested promising in vitro anticancer properties associated with non-conventional modes of action. To gain further mechanistic insight, we have explored here the reactions of these Pt compounds with a few model proteins, i.e., hen egg white lysozyme (HEWL), bovine pancreatic ribonuclease (RNase A), horse heart cytochrome c (Cyt-c) and human serum albumin (HSA), primarily through ESI MS analysis. Characteristic and variegate patterns of reactivity were highlighted in the various cases that appear to depend both on the nature of the Pt complex and of the interacting protein. The protein-bound Pt fragments were identified. In the case of the complex Pt2c, the adducts formed upon reaction with HEWL and RNase A were further characterized by solving the respective crystal structures: this allowed us to determine the exact location of the various Pt binding sites. The implications of the obtained results are discussed in relation to the possible mechanisms of action of these innovative anticancer Pt complexes.