Lorenzo Mucchi

Time of arrival estimation for UWB localizers in realistic environments

This paper investigates time of arrival (ToA) estimation methods for ultra-wide bandwidth (UWB) propagation signals. Different algorithms are implemented in order to detect the direct path in a dense multipath environment. Different suboptimal, low-complex techniques based on peak detection are used to deal with partial overlap of signal paths. A comparison in terms of ranging accuracy, complexity, and parameters sensitivity to propagation conditions is carried out also considering a conventional technique based on threshold detection. In particular, the algorithms are tested on experimental data collected from a measurement campaign performed in a typical office building.

Experimental Characterization of Diversity Navigation

Wireless networks with navigation capability enable mobile devices to both communicate and determine their positions. Diversity navigation employing multiple sensing technologies can overcome the limitation of individual technologies, especially when operating in harsh environments such as indoors. To characterize the diversity of navigation systems in real environments, we performed an extensive measurement campaign, where data from heterogenous sensors were collected simultaneously. The performance of Bayesian navigation algorithms, relying on the particle filter implementation, is evaluated based on measured data from ultrawideband, ZigBee, and inertial sensors. This enables us to quantify the benefits of data fusion as well as the effect of statistical mobility models for real-time diversity navigation.

A new parameter for UWB indoor channel profile identification

This paper proposes a new parameter for identifying the room typology when the receiver is in ultra wideband (UWB) indoor environments. The method proposed does not imply any estimation process at the received signal. The proposed parameter is not only able to clearly distinguish between line-of-sight (LOS) and non-line-of-sight (NLOS) conditions, but it is also capable of ordering the quality of the received signal in two different LOS or NLOS rooms, although the signal-to-noise-ratio (SNR) is the same. Moreover, this parameter is able to distinguish between LOS and NLOS macro groups clearly and, at the same time, to order conditions within these two macro groups (for example, clear LOS condition from Quasi-LOS, i.e., when an object partially shadows the link, etc.). The method proposed in this paper is based on the calculation of the kurtosis index of the sampled received signal. The kurtosis index can be successfully applied to the received signal in order to identify the typology of the link between transmitter and receiver (LOS, Quasi-LOS, high-NLOS, low-NLOS, extreme-low-NLOS). Results are achieved by both real measurements and simulations with IEEE802.15.3a and 4a channel models.

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.

Physical Layer Cryptography and Cognitive Networks

AbstractRecently the huge development of different and heterogeneous wireless communication systems raises the problem of growing spectrum scarcity. Cognitive radio tends to solve this problem by dynamically utilizing the spectrum. Security in cognitive radio network becomes a challenging issue, since more chances are given to attackers by cognitive radio technology compared to conventional wireless network. These weaknesses are introduced by the nature itself of cognitive radio, and they may cause serious impact to the network quality of service. However, to the authors’ knowledge, there are no specific secure protocols for cognitive radio networks. This paper will discuss the vulnerabilities inherent to cognitive radio systems, identify novel types of abuse, classify attacks, and analyze their impact. Security solutions to mitigate such threats will be proposed and discussed. In particular, physical payer security will be taken into account. A new modulation technique, able to encrypt the radio signal without any a priori common secret between the two nodes, was previously proposed by the authors (Mucchi et al. 2009, WPC 51, 67–80; Mucchi et al. 2010, WPC 53, 329–347). The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. This contribution improves the previous works by proposing the noise loop modulation as physical layer security technique for cognitive radio networks.

A Novel Approach for Physical Layer Cryptography in Wireless Networks

Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a “secure” channel. Nowadays a secure wireless channel is not possible. In fact normally the common a priori knowledge is already established (but this is not secure) or by using a non-radio channel (that implies a waste of time and resource). The information is encrypted by means of a private key that must be known by both the transmitter and the receiver. One of the main weak point about security is the private key exchanging interval. The key cannot be public and cannot be known a priori. The problem is how to exchange this private key through a totally secure wireless channel. This contribution deals with the review of the main physical layer techniques for encrypting the information and the proposal of a new physical layer technique ensuring secure communication in a full wireless environment. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. The probability of error/detection is analytically derived for the legal users and for the third unwanted listener (passive or active attacker). Both the case of passive and active attacks have also been implemented and simulated by using Matlab-Simulink software. The analytical results have been compared to the simulated ones. All the results show that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated (passive attack) or denied (active attack) by a third terminal.

Range Estimation in UWB Realistic Environments

This paper investigates time of arrival (ToA) estimation methods for ultra-wide bandwidth (UWB) propagation signals. Different algorithms are implemented in order to detect the direct path in a dense multipath environment. In particular, suboptimal low-complex techniques based on peak detection are used to deal with partial overlap of signal paths. A comparison in terms of ranging accuracy, complexity, and parameters sensitivity to propagation conditions is carried out also considering a conventional technique based on threshold detection. The algorithms are tested on experimental data collected from a measurement campaign performed in a typical office building.

Ultra Wide Band real-time location system for cinematic survey in sports

Our experimental campaign shows how a real-time location system based on Ultra Wide Band (UWB) impulses can be fruitfully used to collect cinematic parameters in order to define the health status of an athlete objectively. The Ubisense UWB system has been used to monitor the performance of a professional athlete during the recovering time after a surgery. The cinematic data has been processed in order to have all the performance comparable. This work demonstrates that the UWB localization can be efficiently used in order to show the increase in the muscular capacity and to measure it.

A New Modulation for Intrinsically Secure Radio Channel in Wireless Systems

Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a “secure” channel. Nowadays a secure wireless channel is not possible. In fact normally the common a priori knowledge is already established (but this is not secure) or by using a non-radio channel (that implies a waste of time and resource). This contribution deals with the proposal of a new modulation technique ensuring secure communication in a full wireless environment. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. The probability of error/detection is analytically derived for the legal users and for the third unwanted listener (passive or active attacker). Both the case of passive and active attacks have also been implemented and simulated by using Matlab-Simulink software. The analytical results have been compared to the simulated ones. All the results show that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated (passive attack) or denied (active attack) by a third terminal.

The Role of Physical Layer Security in IoT: A Novel Perspective

This paper deals with the problem of securing the configuration phase of an Internet of Things (IoT) system. The main drawbacks of current approaches are the focus on specific techniques and methods, and the lack of a cross layer vision of the problem. In a smart environment, each IoT device has limited resources and is often battery operated with limited capabilities (e.g., no keyboard). As a consequence, network security must be carefully analyzed in order to prevent security and privacy issues. In this paper, we will analyze the IoT threats, we will propose a security framework for the device initialization and we will show how physical layer security can effectively boost the security of IoT systems.