Over the coming decades, high-definition situationally aware networks have the potential to create revolutionary applications in the social, scientific, commercial, and military sectors. Ultrawide bandwidth (UWB) technology is a viable candidate for enabling accurate localization capabilities through time-of-arrival (TOA)-based ranging techniques. These techniques exploit the fine delay resolution property of UWB signals by estimating the TOA of the first signal path. Exploiting the full capabilities of UWB TOA estimation can be challenging, especially when operating in harsh propagation environments, since the direct path may not exist or it may not be the strongest. In this paper, we first give an overview of ranging \ud techniques together with the primary sources of TOA error \ud (including propagation effects, clock drift, and interference). \ud We then describe fundamental TOA bounds (such as the \ud Cramér–Rao bound and the tighter Ziv–Zakai bound) in both \ud ideal and multipath environments. These bounds serve as useful benchmarks in assessing the performance of TOA estimation techniques. We also explore practical low-complexity TOA \ud estimation techniques and analyze their performance in the \ud presence of multipath and interference using IEEE 802.15.4a \ud channel models as well as experimental data measured in \ud indoor residential environments

Abstract-We present new exponential bounds for the Gaussian function (one-and two-dimensional) and its inverse, and for -ary phase-shift-keying (MPSK), -ary differential phase-shift-keying (MDPSK) error probabilities over additive white Gaussian noise channels. More precisely, the new bounds are in the form of the sum of exponential functions that, in the limit, approach the exact value. Then, a quite accurate and simple approximate expression given by the sum of two exponential functions is reported. The results are applied to the general problem of evaluating the average error probability in fading channels. Some examples of applications are also presented for the computation of the pairwise error probability of space-time codes and the average error probability of MPSK and MDPSK in fading channels. Index Terms-Bounds, fading,-ary differential phase-shift keying (MDPSK), -ary phase-shift keying (MPSK), function, space-time codes (STCs).

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Network localization and navigation give rise to a new paradigm for communications and contextual data collection, enabling a variety of new applications that rely on position information of mobile nodes (agents). The performance of such networks can be significantly improved via the use of cooperation. Therefore, a deep understanding of information exchange and cooperation in the network is crucial for the design of location-aware networks. This article presents an exploration of cooperative network localization and navigation from a theoretical foundation to applications, covering technologies and spatiotemporal cooperative algorithms

In the last decade, the research on and the technology for outdoor tracking have seen an explosion of advances. It is expected that in the near future we will witness similar trends for indoor scenarios where people spend more than 70% of their lives. The rationale for this is that there is a need for reliable and high-definition real-time tracking systems that have the ability to operate in indoor environments, thus complementing those based on satellite technologies such as GPS. The indoor environments are very challenging and, as a result, a large variety of technologies have been proposed for coping with them, but no legacy solution has emerged yet. This paper presents a survey on indoor wireless tracking of mobile nodes from a signal processing perspective. It can be argued that the indoor tracking problem is more challenging than the one on indoor localization. The reason is simple -from a set of measurements one has to estimate not one location but a series of correlated locations of a mobile node. The paper illustrates the theory, the main tools and the most promising technologies for indoor tracking. New directions of research are also discussed.Index Terms-Indoor tracking, simultaneous localization and mapping, Bayesian filtering, data fusion, technologies for tracking. I. INTRODUCTIONIndoor real time locating systems (RTLS) have been gaining relevance due to the widespread advances of devices and technologies and the necessity for seamless solutions in location-based services. An important component of RTLS is indoor tracking where objects, vehicles or people (in the sequel referred to as mobile nodes) are tracked within a building or any enclosed structure. Examples include tracking of products through manufacturing lines, first-responder navigation, asset

Wireless sensor networks (WSNs) enable new applications and require non-conventional paradigms for protocol design due to several constraints. Owing to the requirement for low device complexity together with low energy consumption (i.e., long network lifetime), a proper balance between communication and signal/data processing capabilities must be found. This motivates a huge effort in research activities, standardization process, and industrial investments on this field since the last decade. This survey paper aims at reporting an overview of WSNs technologies, main applications and standards, features in WSNs design, and evolutions. In particular, some peculiar applications, such as those based on environmental monitoring, are discussed and design strategies highlighted; a case study based on a real implementation is also reported. Trends and possible evolutions are traced. Emphasis is given to the IEEE 802.15.4 technology, which enables many applications of WSNs. Some example of performance characteristics of 802.15.4-based networks are shown and discussed as a function of the size of the WSN and the data type to be exchanged among nodes.

AbstrAct5G technologies present a new paradigm to provide connectivity to vehicles, in support of high data-rate services, complementing existing inter-vehicle communication standards based on IEEE 802.11p. As we argue, the specific signal characteristics of 5G communication turn out to be highly conducive for vehicle positioning. Hence, 5G can work in synergy with existing on-vehicle positioning and mapping systems to provide redundancy for certain applications, in particular automated driving. This article provides an overview of the evolution of cellular positioning and discusses the key properties of 5G as they relate to vehicular positioning. Open research challenges are presented. requirements for VehiculAr PositioningWith the increase of automated driving in various forms (highway assistance driving, automatic cruise control, self-parking, up to fully autonomous driving) comes a need for precise positioning information. Positioning of vehicles is achieved through a variety of technologies, as illustrated in Fig. 1, including global navigation satellite-based systems (GNSS), radar, mono and stereo cameras, and laser scanners (lidar), which are fused to give the vehicle an understanding of the environment and its location within this environment. The environment is encoded through a map, which is either stored offline or computed online. The process of learning the environment and building detailed maps using onboard sensors is known as mapping. Different positioning applications have different requirements, which are expressed in terms of accuracy, latency, reliability, and cost. On one hand, standard vehicular navigation applications require only a few meters of absolute positioning accuracy, second-level latency, and low reliability (frequent outages are tolerable), but must rely on low-cost sensors. On the other hand, the safety-critical application of autonomous driving will require centimeter-level absolute and relative positioning accuracy, latencies on the order of tens of milliseconds, and high reliability, but can rely on a more expensive suite of sensors. An overview of the accuracy requirements for several key applications is shown in Table 1.GNSS, which has been the workhorse for vehicular absolute positioning in military, professional, and personal navigation, leads to uncertainties on the order of a few meters. Complemented by dedicated base stations, real-time kinematic GNSS further improves the accuracy down to the centimeter level. However, GNSS fails to work in certain common conditions, such as under tree canopies, in the presence of GNSS jammers, and in dense urban environments, due to the blocking of GNSS signals by buildings. Moreover, GNSS is limited by significant latency and low refresh rate, which are key requirements for guaranteeing safety.For relative positioning, onboard sensors such as cameras, radars, and lidars can generally operate well under these GNSS-challenged conditions, and provide very precise information. However, these sensors are costly in terms of computational ...

Assisted living (AL) technologies, enabled by technical advances such as the advent of the Internet-of-Things, are increasingly gaining importance in our ageing society. This article discusses the potential of future high-accuracy localization systems as a key component of AL applications. Accurate location information can be tremendously useful to realize, e.g., behavioral monitoring, fall detection, and real-time assistance. Such services are expected to provide older adults and people with disabilities with more independence and thus to reduce the cost for caretaking.Total cost of ownership and ease of installation are paramount to make sensor systems for AL viable. In case of a radiobased indoor localization system, this implies that a conventional solution is unlikely to gain widespread adoption because of its requirement to install multiple fixed nodes (anchors) in each room. This paper therefore places its focus on (i) discussing radiolocalization methods that reduce the required infrastructure by exploiting information from reflected multipath components and (ii) showing that knowledge about the propagation environment enables localization with high accuracy and robustness. It is demonstrated that new millimeter-wave (mm-wave) technology, under investigation for 5G communications systems, will be able to provide cm-accuracy indoor localization in a robust manner, ideally suited for AL.