Simone Morosi

Comparison of CDMA and OFDM techniques for downstream power-line communications on low voltage grid

This paper provides a fair comparison between direct sequence code division multiple access (DS-CDMA) and orthogonal frequency division multiplexing (OFDM) systems for broadband downstream power-line communications (PLCs). The considered schemes seem particularly suitable for high bit rate broadcast flexible communications on low voltage grid in order to guarantee local access. The performance of the considered systems is expressed in terms of bit error rate (BER), derived by simulations under the assumptions of frequency-selective multipath fading channel and additive colored Gaussian noise according to the in-building networks model, under the same overall working conditions of bandwidth occupation, transmitted power, and global data rate.

Sleep mode management in cellular networks: a traffic based technique enabling energy saving

Because of the environmental policies that pursue a significant reduction of global greenhouse gas and to the ambition of the network operators to keep under control operational and maintenance expenditures, energy efficiency has recently become one of the most relevant issues for present and future research activities. This contribution deals with the management of the base station sleep mode in a cellular network. The forecasting based sleep mode algorithm, justified by daily and weekly periodic behaviour of traffic, is presented and evaluated for general deployments of second and third generation cellular networks. The energy consumption of each base station and the area power consumption are the metrics, which are considered for our simulations. The results show a significant increase of the energy efficiency during low traffic periods with respect to the usual scenario, thanks to the adoption of the proposed strategy. The forecasting based sleep mode algorithm has been also compared with a strategy based on real-time measurements and the results show similar performances while the number of updates of the network configuration and the global complexity are decreased. Copyright

SALICE project: Satellite-Assisted Localization and Communication Systems for Emergency Services

Restoring the connectivity in the emergency areas and providing NAV/COM services able to support and coordinate the rescue teams represent two of the main telecommunication needs for efficient emergency situation management. The SALICE (Satellite-Assisted LocalIzation and Communication system for Emergency services) Project aimed at identifying the system architecture and the most suitable solutions to be adopted in the future integrated reconfigurable NAV/COM systems and to analyze their feasibility in realistic emergency scenarios. The article analyzes the proposed strategies and the most significant project results in pursuing both the global coverage of the emergency areas and the development of a reconfigurable and cooperative NAV/COM system.

Aerospace Communications for Emergency Applications

In this paper, the current trends and the most recent advancements in the utilization of aerospace communications for emergency rescue applications will be discussed, with a special focus on the integration of the aerospace segment with terrestrial backbones and ad hoc terrestrial networks for both data connections and assisted localization (information about position is essential in emergency relief).

A new algorithm for blind adaptive multiuser detection in frequency selective multipath fading channel

This paper deals with a modified version of a blind adaptive multiuser detector for direct sequence code-division multiple-access (DS-CDMA) wireless communication systems which is named precombining blind adaptive multiuser detector (PBA-MUD). The main properties of this receiver are low complexity, multiple-access interference mitigation and remarkable near-far resistance in time-varying multipath fading scenarios. In particular, the PBA-MUD is based on a blind adaptive algorithm that allows the detector to avoid deep fading impairments and the cancellation of the desired signal due to signature sequence mismatch. Nevertheless, such a receiver experiences a performance degradation in fast fading channels. In order to overcome this problem, a window reprocessing technique (Del Re et al., 2001) was introduced which yielded a new blind detection algorithm. It will be shown that this receiver, together with this new algorithm [precombining reprocessing window blind adaptive multiuser detector (PWBA-MUD)] allows a high performance without requiring training sequences or the knowledge of the interfering signature waveforms in multipath fast fading channels.

Cooperative Delay Diversity in Hybrid Satellite/Terrestrial DVB-SH System

In this paper we study simple and feasible cooperative relaying strategies which rely on the introduction of the Delay Diversity technique in a DVB-SH compliant hybrid satellite/terrestrial network. These strategies are investigated in a public emergency scenario where the adoption of a hybrid network combined with the cooperative diversity techniques guarantees the connection between the incident area and the external areas: particularly, the drawbacks of the Non-Line-Of-Sight (NLOS) propagation are mitigated. The proposed schemes are analysed and compared, highlighting the assumptions required and the simulation results with respect to the satellite-only and the terrestrial-only cases.

A rate adaptive bit-loading algorithm for in-building power-line communications based on DMT-modulated systems

This paper deals with a variable rate discrete multitone modulation system for broadband power-line communications, based on the bit-loading algorithm proposed by Leke and Cioffi. In the proposed system a suitable least mean square channel estimator is considered, which is based on the insertion of a training sequence (TS). The proposed approach will be compared with the ideal channel estimates, showing its effectiveness. Moreover, different TS lengths will be compared. The system performance, expressed in terms of bit rate and bit-error rate, is derived by simulation with and without estimation errors. The propagation environment has been assumed as a frequency-selective multipath fading channel with additive colored Gaussian noise, according to the in-building networks model

Improving cellular network energy efficiency by joint management of sleep mode and transmission power

Energy efficiency is one of the main challenges to be faced by mobile communications in the near future. The growth of the mobile communications market which is boosted by the increasing penetration of smartphones and laptops requires an increase of the network capacity and, consequently, a great leap forward also for the infrastructures. In this scenario, in order to reduce the operative expenditures, the network operators pay attention to energy saving strategies that may also contribute to the reduction of greenhouse emissions. In this paper the exponential smoothing technique is applied to forecast traffic in a given area considering daily and weekly variations. The availability of a reliable prediction of the future traffic values allows the adaptation of macro base station transmission power and the introduction of a sleep mode for micro base stations and permits to guarantee the requested network capacity while saving energy consumption. Results show the effectiveness of traffic forecast technique for capacity prediction and the usefulness of the proposed algorithms for energy efficiency maximization, affording very good performance, very close to the optimum one.

Feasibility study of a SDR-based reconfigurable terminal for emergency applications

Today, more attention is paid to emergency systems and rescuer organizations due to the increasing sensitivity to natural disasters and terrorist attacks. In this paper, we would consider the feasibility of telecommunication technologies that can enhance the interconnection between accident zones and rescue teams. A novel philosophy inspired by Software Defined Radios is proposed in order to design a reconfigurable receiver for rescue team assistance in emergency scenarios, which can encompass some basic functionalities, i) spectrum sensing and automatic mode identification, ii) dynamic multistandard reconfigurability, iii) navigation and communication integration. Results shown can prove the feasibility of the software implementation of the reconfigurable terminal over suitable processing architectures, characterized by affordable cost and open-source software development.

SALICE - Satellite-Assisted LocalIzation and Communication systems for Emergency services

This paper describes the SALICE (Satellite-Assisted LocalIzation and Communication systems for Emergency services) project, an Italian National Research Project which has been recently funded by the Italian Ministry of Research; the SALICE project aims at identifying the solutions which can be adopted in an integrated reconfigurable NAV/COM device and studying its feasibility in realistic scenarios. The first goal of the SALICE project is the definition of the baseline scenarios and system architecture which will allow the design of new and effective solutions for what concerns integrated communications and localization techniques, Software Defined Radio (SDR) NAV/COM devices, satellite and HAPS integration in the rescue services, heterogeneous solutions in the area of intervention (IAN, Incident Area Network). Particular attention will be devoted to the optimization of the resources management strategies and to the cooperative localization of rescue entities (persons and means) that intervene in emergency situations.