The growing complexity of telecommunication networks increases the need for automated monitoring and detection of incidents. The increasing amount of data generated by current information and communication technologies equipment can be used to identify abnormal behavior and detect anomalies. In this paper, we propose a volume-based real-time solution for anomaly detection in operator networks. The proposal is based on a seasonal autoregressive integrated moving average (SARIMA) forecasting of time-series data, and the identification of outliers. We validate the proposed solution using real traffic traces from a nationwide operator’s network which we make publicly available. Our experimental results show that the proposed solution outperforms baseline approaches in terms of precision, being able to substantially reduce the amount of false positives, while maintaining the same level of recall.

This paper describes the NextPerception project’s outcomes organized as examples motivated by user stories. The project developed next-generation perception sensors and enhanced the distributed intelligence paradigm to build versatile, secure, reliable and proactive human monitoring systems, in turn applied in use cases in health and automotive domains.

Terahertz communications are envisioned as a key enabler for 6G networks. The abundant spectrum available in such ultra high frequencies has the potential to increase network capacity to huge data rates. However, they are extremely affected by blockages, to the point of disrupting ongoing communications. In this paper, we elaborate on the relevance of predicting visibility between users and access points (APs) to improve the performance of THz-based networks by minimizing blockages, that is, maximizing network availability, while at the same time keeping a low reconfiguration overhead. We propose a novel approach to address this problem, by combining a neural network (NN) for predicting future user–AP visibility probability, with a probability threshold for AP reselection to avoid unnecessary reconfigurations. Our experimental results demonstrate that current state-of-the-art handover mechanisms based on received signal strength are not adequate for THz communications, since they are ill-suited to handle hard blockages. Our proposed NN-based solution significantly outperforms them, demonstrating the interest of our strategy as a research line.

Physical-Layer Network Coding (PNC) is an effective technique to improve the throughput and latency in wireless networks. However, there are two major challenges for PNC, especially when using higher order modulations: 1) phase synchronization and power control at the paired User Equipments (UEs); and 2) the ambiguity removal of the PNC mapping at the relay node. To address these challenges, in this paper, we apply power control at transmitting UEs and exploit Reconfigurable Intelligent Surfaces (RISs) to synchronize the phase of the transmitted signals and ensure that they arrive at the relay with the same power and phase rotation. Then, we employ modular addition for an unambiguous PNC mapping for M-ary Quadrature Amplitude Modulations (M-QAM). We evaluate the performance of the system in the framework of Orthogonal Frequency Division Multiplexing (OFDM)-PNC for different RIS sizes and modulation orders. Furthermore, we study the sensitivity of PNC systems for Channel Estimation Error (CEE). The results reveal that 1) PNC systems show quite higher sensitivity to CEE compared with RIS-assisted one-way relay channel systems; 2) when the CEE is low, RIS can considerably enhance the Signal-to-Noise Ratio (SNR) of the PNC system, e.g., for a Bit Error Rate (BER) of 10−3(without channel coding), increasing the RIS size from one to 256 elements in 28 GHz band leads to 200% improvement in SNR.

Integrated Access and Backhaul (IAB) has been recently proposed by 3GPP to enable network operators to deploy fifth generation (5G) mobile networks with reduced costs. In this paper, we propose to use IAB to build a dynamic wireless backhaul network capable to provide additional capacity to those Base Stations (BS) experiencing congestion momentarily. As the mobile traffic demand varies across time and space, and the number of slice combinations deployed in a BS can be prohibitively high, we propose to use Deep Reinforcement Learning (DRL) to select, from a set of candidate BSs, the one that can provide backhaul capacity for each of the slices deployed in a congested BS. Our results show that a Double Deep Q-Network (DDQN) agent using a fully connected neural network and the Rectified Linear Unit (ReLU) activation function with only one hidden layer is capable to perform the BS selection task successfully, without any failure during the test phase, after being trained for around 20 episodes.

Abstract In this article, we evaluate the first experience of computation offloading from drones to real fifth‐generation (5G) operator systems, including commercial and private carrier‐grade 5G networks. A follow‐me drone service was implemented as a representative testbed of remote video analytics. In this application, an image of a person from a drone camera is processed at the edge, and image tracking displacements are translated into positioning commands that are sent back to the drone, so that the drone keeps the camera focused on the person at all times. The application is characterised to identify the processing and communication contributions to service delay. Then, we evaluate the latency of the application in a real non standalone 5G operator network, a standalone carrier‐grade 5G private network, and, to compare these results with previous research, a Wi‐Fi wireless local area network. We considered both multi‐access edge computing (MEC) and cloud offloading scenarios. Onboard computing was also evaluated to assess the trade‐offs with task offloading. The results determine the network configurations that are feasible for the follow‐me application use case depending on the mobility of the end user, and to what extent MEC is advantageous over a state‐of‐the‐art cloud service.

Human activity recognition (HAR) for boxing training typically requires specialized hardware or large labeled datasets to identify different types of punches and analyze their basic properties. However, measuring the unpredictability of boxers, a key characteristic to deceive opponents during combats, has remained an unexplored challenge. We tackled this challenge by combining a series of novel techniques and ideas. Unpredictability was computed as the entropy of the trajectories of the Markov chain characterizing the training session, estimated from the combinations (sequences of punches) thrown by the boxer to the training bag. Punch combinations were obtained by detecting punches as outliers in the raw acceleration sensor datastream coming from the bag, and separating them by type with an ensemble of PCA+GMM clusters. Punches were then divided into combinations using statistical analysis of separation intervals. The detection procedure works even with noisy data, in contrast to force-threshold methods commonly reported in the literature. As distinctive features of our system, it uses only unlabeled data from the current training session, and sensor positions and orientations inside the bag are unconstrained. However, punch clustering achieves up to 94% accuracy, comparable to state-of-the-art supervised approaches. These features are currently unseen in the literature and demonstrate the capacity for unsupervised learning techniques to address challenging problems in sports. Multiple validation experiments were consistent with boxers’ level and session performance. Overall, our approach provides significant contributions to the field of HAR and has the potential to improve the way boxing and other sports are trained and evaluated.

Multi-Access Edge Computing (MEC) is one of the fundamental technologies committed to satisfy the requirements targeted by 5G and beyond networks, such as low latency and massive communications. Nevertheless, deploying a large-scale MEC infrastructure will require a huge investment that should be minimized by optimizing the resources at edge locations, and to use centralized datacenters when possible. Thus, automated orchestration is essential for implementing mechanisms that deploy applications at the best location and even that relocate them, when necessary, to satisfy the Quality of Service (QoS) requirements. In this paper we describe an architecture for this purpose, which we have implemented in an experiment that demonstrates how Open Source MANO (OSM) can automate the relocation of a video processing application that helps drivers to remember the latest traffic sign viewed. Our proposal also includes two new components: the first one maintains the state of the applications when they are deployed at a new location, and the second one allows OSM managing the Open Network Edge Services Software (OpenNESS) edge platform. Finally, we elaborate on open challenges in MEC platforms.

Over the last few years the Multi-Access Edge Computing (MEC) paradigm has been gaining attention as a key enabler for low latency applications in cellular networks. In this paper we analyze a solution based on Software-Defined Networking (SDN) for supporting dynamic and transparent relocation of the endpoint of a communication from the core to an edge infrastructure in current cellular networks. We also provide results of real-world experiments utilising a Network Function Virtualization (NFV)-based testbed for evaluating session continuity and latency reduction when the gateway or anchor point used by two end User Equipments (UEs) is relocated to edge resources. Our experimental results show that the communication can be dynamically relocated from the core to the edge while guaranteeing session continuity during the whole process. We demonstrate that the mechanism is able to reduce latency considerably when the core network is congested.

Summary Container platforms are increasingly being used to deploy cloud‐based services. Nevertheless, many cloud services are also demanding graphics processing units (GPUs) to accelerate different applications that make use of their parallel architecture, such as deep learning or just video processing. Thus, different container technologies, such as Docker and Kubernetes, are implementing GPU support. Some effort is being devoted to design algorithms to schedule applications into heterogeneous computing systems that use CPUs and GPUs together. This article is part of this effort, and we describe how to build a dynamic scheduling platform for Kubernetes that is able to manage the deployment of Docker containers in a heterogeneous cluster, which we call KubCG. This platform implements a new scheduler that optimizes the deployment of new containers by taking into account the Kubernetes Pod timeline and the historical information about the execution of the containers. We have performed different tests to validate this new algorithm, and KubCG was able to reduce the time to complete different tasks down to a 64% of the original time in our different experiments.

Summary Network “softwarization” is enabling new features such as detecting the risk to violate a Service Level Agreement (SLA) and performing the required automated control actions on a network slice. A real‐time Network Function Virtualization (NFV) Management and Orchestration (MANO) system should detect any SLA degradation and act to recover the SLA. The closed‐loop automation approach monitors the state of the network and triggers policy‐based control actions when needed. The delay between the detection of an SLA issue and the completion of a correcting action is critical for satisfying latency‐related SLAs. Thus, in this article we propose this delay as a new key performance indicator (KPI) for NFV MANO systems, which we call Closed‐Loop Orchestration Delay (CLOD). CLOD is subdivided into independent time intervals that depend on the NFV MANO platform, the target Virtualized Infrastructure Management (VIM) and the target virtual network function (VNF) software. CLOD is evaluated on a real use case: a latency‐sensitive elastic network slice in which Internet user round‐trip time (RTT) is monitored. When the service level of the slice drops below a predefined limit a new data plane is deployed near the user reducing latency. In the evaluation, we considered two approaches: (i) a general implementation of the NFV MANO architecture based on the Open Network Automation Platform (ONAP) and OpenStack and (ii) an optimized ad‐hoc baseline implementation to minimize CLOD. We provide the details of both implementations and compare their CLODs leading to useful insights for the NFV MANO community.

Multi-Access Edge Computing (MEC) will allow implementing low-latency services that have been unfeasible so far. The European Telecommunications Standards Institute (ETSI) and the 3rd Generation Partnership Project (3GPP) are working towards the standardization of MEC in 5G networks and the corresponding solutions for routing user traffic to applications in local area networks. Nevertheless, there are neither practical implementations for dynamically relocating applications from the core to a MEC host nor from one MEC host to another ensuring service continuity. In this article we propose a solution based on Software-Defined Networking (SDN) to create a new instance of the IP anchor point to dynamically redirect User Equipment (UE) traffic to a new physical location (e.g., an edge infrastructure). We also present a novel approach that leverages SDN to replicate the previous context of the connection in the new instance of the IP anchor point, thus guaranteeing Session and Service Continuity (SSC), and compare it with alternative state replication strategies. This approach can be used to implement edge services in 4G or 5G networks.

The sixth-generation (6G) of wireless communications systems will significantly rely on fog/edge network architectures for service provisioning. To realize this vision, AI-based fog/edge enabled reinforcement solutions are needed to serve highly stringent applications using dynamically varying resources. In this paper, we propose a cognitive dynamic fog/edge network where primary nodes (PNs) temporarily share their resources and act as fog nodes (FNs) for secondary nodes (SNs). Under this architecture, that unleashes multiple access opportunities, we design distributed fog probing schemes for SNs to search for available connections to access neighbouring FNs. Since the availability of these connections varies in time, we develop strategies to enhance the robustness to the uncertain availability of channels and fog nodes, and reinforce the connections with the FNs. A robustness control optimization is formulated with the aim to maximize the expected total long-term reliability of SNs’ transmissions. The problem is solved by an online robustness control (ORC) algorithm that involves online fog probing and an index-based connectivity activation policy derived from restless multi-armed bandits (RMABs) model. Simulation results show that our ORC scheme significantly improves the network robustness, the connectivity reliability and the number of completed transmissions. In addition, by activating the connections with higher indexes, the total long-term reliability optimization problem is solved with low complexity.

Global optimization of access point (AP) assignment to user terminals requires efficient monitoring of user behavior, fast decision algorithms, efficient control signaling, and fast AP reassignment mechanisms. In this scenario, software defined networking (SDN) technology may be suitable for network monitoring, signaling, and control. We recently proposed embedding virtual switches in user terminals for direct management by an SDN controller, further contributing to SDN-oriented access network optimization. However, since users may restrict terminal-side traffic monitoring for privacy reasons (a common assumption by previous authors), we infer user traffic classes at the APs. On the other hand, since handovers will be more frequent in dense small-cell networks (e.g., mmWave-based 5G deployments will require dense network topologies with inter-site distances of ~150-200 m), the delay to take assignment decisions should be minimal. To this end, we propose taking fast decisions based exclusively on extremely simple network-side application flow-type predictions based on past user behavior. Using real data we show that a centralized allocation algorithm based on those predictions achieves network utilization levels that approximate those of optimal allocations. We also test a distributed version of this algorithm. Finally, we quantify the elapsed time since a user traffic event takes place until its terminal is assigned an AP, when needed.

Summary Many recommender systems are currently available for proposing content (movies, TV series, music, etc.) to users according to different profiling metrics, such as ratings of previously consumed items and ratings of people with similar tastes. Recommendation algorithms are typically executed by powerful servers, as they are computationally expensive. In this paper, we propose a new software solution to improve the performance of recommender systems. Its implementation relies heavily on Apache Spark technology to speed up the computation of recommendation algorithms. It also includes a webserver, an API REST, and a content cache. To prove that our solution is valid and adequate, we have developed a movie recommender system based on two methods, both tested on the freely available Movielens and Netflix datasets. Performance was assessed by calculating root‐mean‐square error values and the times needed to produce a recommendation. We also provide quantitative measures of the speed improvement of the recommendation algorithms when the implementation is supported by a computing cluster. The contribution of this paper lies in the fact that our solution, which improves the performance of competitor recommender systems, is the first proposal combining a webserver, an API REST, a content cache and Apache Spark technology. Copyright © 2016 John Wiley & Sons, Ltd.

In this work we integrate user terminals into an SDN architecture that allows global network optimization. We embed an SDN virtual switch into a mobile user terminal in such a way that a centralized controller, using both terminal and network-side information, can decide which access network terminal should connect to. User profiling and terminal interface configuration are integral parts of the architecture.

Fourth Generation (4G) cellular networks have millions of active subscribers around the globe. These networks have allowed data rates that were traditionally out of reach of mobile terminals and, ultimately, opened up new business opportunities for content providers. However, 4G carriers are also deploying WiFi hotspots as a complementary technology to access their core networks and have found it necessary to offload traffic from their cellular access networks to aleviate the serious congestion problems they were facing. These congestion are expected to persist and even worsen in the transition to 5G cellular networks. In this work we borrow ideas from the field of Software-Defined Networks (SDNs) to include user terminals as an integral part of that paradigm, thus contributing to global network optimization. By integrating a virtual switch into the terminals, a centralized controller can decide which access network the terminals should connect to based on both terminal (user profiling) and network-side information. A novel aspect of our proposal is that wireless terminal interface configuration is an integral part of the architecture.

Software-Defined Networking (SDN) has gained momentum in recent years, in a bid to transform networking ecosystems. It has already been applied to data center networks and wide area networks, such as Google's WAN. A software-defined approach is thus a reasonable candidate architecture for other highly dynamic environments such as future 5G mobile networks. This paper presents a two-level software-defined approach for the future 5G architecture at the network and radio access layer. At each level, a dedicated logical centralised controller and northbound/southbound Application Programming Interfaces are defined. Two cross-layer schemes are also introduced for interaction between controllers.

SUMMARY Traditionally, call authentication and security have not raised user concerns because wiretapping requires physical access to the phone line and special equipment. However, Voice over Internet Protocol (VoIP) communications are becoming increasingly popular, and there is the perception that they may be easier to intercept or impersonate (thus creating higher demand for security solutions), especially if the connection occurs over wireless links. The Session Initiation Protocol is widely used for managing voice and video communications over the Internet, and the Real‐time Transport Protocol is used to carry voice and/or video streams. Session Initiation Protocol, however, was not designed with security in mind and is vulnerable to attacks. Furthermore, there are cases in which it is necessary to authenticate the call participants (e.g., when they are asked to disclose confidential information). There are few practical solutions to this problem, essentially because they require complex infrastructures to manage keys and certificates. In this paper, we solve this problem with a novel approach: the use of national public key infrastructures in combination with national Electronic Identity smart cards, created by governments to execute trusted electronic transactions and establish trusted identities. In addition, we will show how our approach enables new use cases (e.g., institutions – hospitals, banks, government, etc. – can be confident that they exchange confidential information to the intended person and vice versa) and simplifies the steps necessary to secure and authenticate a VoIP communication with ZRTP, simplifying and therefore encouraging the use of secure VoIP communications between authenticated users. Copyright © 2012 John Wiley & Sons, Ltd.

Road safety and vehicle information applications may be jointly enhanced by IEEE 802.11 communications and Delay- and Disruption-Tolerant Networking, thus allowing for reliable and efficient communication in a highly mobile environment with frequent network disruptions and short inter-node contacts. Previous work on this topic has addressed several challenges of vehicular opportunistic communications such as routing and packet loss problems. In this paper we focus on the optimization of the throughput of opportunistic links. This throughput drops with the speed of moving vehicles because the effective communication interval is limited by the time the nodes lie within mutual radio range. We study how this effective communication interval is affected by possible modifications of the protocol stacks involved, and draw some useful conclusions about their practical application.

An increasing number of new geolocation services are exploiting the new capabilities of smartphones, most of which incorporate GPS location. There are fewer applications for providing indoor location, partly due to the cost of the required infrastructure. In this paper, we present QR-Maps, a simple and efficient tool that can be used in smartphones to obtain accurate indoor user locations. This tool employs QR-Codes containing a short text which indicates locations shown within a custom Google map. The proposed solution is cheaper than other approaches based on wireless technologies.

As the number of mobile devices grow at a rapid pace, the heterogeneity in their sensing and user interaction capabilities is also increasing. Mobile devices are increasingly being equipped with sensors such as accelerometers, gyros and other gesture sensitive capabilities which propel user experiences beyond the usual keyboard-mouse-touch paradigm. A natural question is how can specific sensors of different devices inter-operate on-demand in a seamless fashion so that they can be composed together into a user interface providing a rich and natural user experience. For example, it should be possible to use the accelerometer in a mobile phone as an input device to control a video game running on a PC, or a high-definition camera attached to a television to act as the input video source for a video chat session running on a mobile phone. In this paper we present a system framework and architecture which enables the seamless interoperability and composition of sensing and user interaction capabilities of different devices into a unified user interface, in an application-agnostic manner.

Authorities recommend the practice of moderate physical activity to improve health and quality of life, but sometimes it is difficult to find the willpower or the motivation to reserve a few minutes to exercise. In this paper we describe a new tool designed to help users to practice sport and record their achievements, which makes the activity more social (finding friends, sharing results, etc.). Furthermore, this tool has been integrated in the "Ubiquitous Oulu", an intelligent city that provides the building blocks to bring it closer to citizens. In this real-life environment we had the opportunity to assess the technical viability of RunWithUs and to identify the main interests of its potential users.

We present a service model that allows terminals to extend their capabilities by delivering services to intelligent infrastructures. For example, a terminal may deliver a pack containing a visualization application and a file to an infrastructure screen. We also present a variant where a user can invite other users to access a shared service on the infrastructure, from other terminals.

Sharing documents across different platforms is highly necessary nowadays. However, many devices, as embedded ones, cannot deal with formats like PDF or PowerPoint, despite their widespread use. In this paper we propose an automated format conversion system to allow the visualization of formats that are not supported in simple multimedia embedded devices.

In the nVoD (near video-on-demand) paradigm, video is distributed through broadcast channels with constrained bandwidth, so that at reception there is a bounded playback start time that is independent of the number of users. In other words, there is unlimited scalability for low bandwidth cost, at the expense of a bounded start time. Thus, regarding bandwidth, nVoD schemas are well suited for satellite channels, so packet losses have not been considered in their context for a long time. Recent research based on digital fountains and intrinsic redundancy of nVoD transmissions has produced nVoD protocols with correction capabilities, which have little or zero impact on bandwidth usage. The authors analyse the most recent proposals using satellite channel models and compare them in terms of error correction performance and client and server resources.

Most all-optical switching paradigms assume that different wavelengths are switched independently, which limits scalability. In optical cell switching (OCS), time is divided into time slots of fixed size by time-division multiplexing, and the wavelengths in a time slot are all bundled. Thus, each OCS switch (OCX) has a single switching plane and performs mere time-space switching. In OCS, each OCX requires optical slot synchronizers (OSYNs) at all inputs for the arrival slots to be aligned, so that cells can be simultaneously forwarded. In a recent OCS paradigm -not-aligned OCS-, the OSYNs and the alignment process are no longer required. Cell shifting still takes place inside the OCXs for minimizing the gaps between cells, but it is not necessary to align them to a reference time. Not-aligned OCS has clear advantages over aligned OCS: the total number of fiber delay loops (FDLs) and the hardware cost are reduced, and the number of switching operations is also lower. Moreover, cell arrival time to the switch is not critical, and the network becomes simpler and more flexible. In this paper, we propose a new distributed resource scheduling algorithm for not-aligned OCS networks, which takes connection blocking probability to reasonable values for practical loads.

As wireless mesh networks become more widely deployed, media streaming in such networks poses a pressing research issue because of the increasing importance of multimedia applications. The challenge with wireless mesh networks is the time-varying wireless channel compounded by multi-hop transmission. However, wireless mesh networks also present an opportunity, i.e., the redundancy provided by broadcast wireless media and mesh connectivity. In this paper, we present a joint interchannel and network coding schema to take advantage of this opportunity and to overcome the challenge of wireless mesh networks. We evaluate of the proposed joint coding through both mathematical analysis and computer simulation. The results demonstrate significant benefits in terms of protection against packet losses and bandwidth utilization of the joint coding schema.

Abstract For a long time, the design of relational databases has focused on the optimization of atomic transactions (insert, select, update or delete). Currently, relational databases store tactical information of data warehouses, mainly for select‐like operations. However, the database paradigm has evolved, and nowadays on‐line analytical processing (OLAP) systems handle strategic information for further analysis. These systems enable fast, interactive and consistent information analysis of data warehouses, including shared calculations and allocations. OLAP and data warehouses jointly allow multidimensional data views, turning raw data into knowledge. OLAP allows ‘slice and dice’ navigation and a top‐down perspective of data hierarchies. In this paper, we describe our experience in the migration from a large relational database management system to an OLAP system on top of a relational layer (the data warehouse), and the resulting contributions in open‐source ROLAP optimization. Existing open‐source ROLAP technologies rely on summarized tables with materialized aggregate views to improve system performance (in terms of response time). The design and maintenance of those tables are cumbersome. Instead, we intensively exploit cache memory, where key data reside, yielding low response times. A cold start process brings summarized data from the relational database to cache memory, subsequently reducing the response time. We ensure concurrent access to the summarized data, as well as consistency when the relational database updates data. We also improve the OLAP functionality, by providing new features for automating the creation of calculated members. This makes it possible to define new measures on the fly using virtual dimensions, without re‐designing the multidimensional cube. We have chosen the XML/Ade factostandard for service provision. Copyright © 2008 John Wiley & Sons, Ltd.

IEEE 802.11p is a technology used for communication between cars, related to security issues, warning of incidents or mere exchange of different types of information. Future cars will have the ability to communicate to other cars and roadside data systems to spread information about congestion, road conditions and accidents. They will also access travel-related Internet services, publicity from business nearby, tourist information or even exchange user files. In this paper a highly configurable agent based simulator that models communication between cars in an urban environment will be presented. Using it, different measurements will be taken, which will allow us to analyze this technology in different scenarios.

Abstract This paper presents the development experience and the evaluation of a system to emulate interactive features of Access Grid virtual rooms (venues) at Web endpoints. The system includes a toolset to demultiplex Access Grid sources, transcode them to adequate formats for Internet distribution and store the resulting multimedia streams in repositories in real time. A specialized server asynchronously delivers those streams to standard Web browsers, which synchronize them and emulate typical Access Grid interactive features such as multiple windows or dynamic video selection. Web browsers can compose multiple independent streams. We call the resulting paradigm Presentations on Demand. From the point of view of software practice, the system relies on a combination of SMIL scripts, CSS and Javascript. Copyright © 2008 John Wiley & Sons, Ltd.

HomePlug powerline communications networks link individual computers or network segments via low-voltage power lines. The powerline medium is a harsh channel, since it varies in time and has a high attenuation. This makes difficult to communicate different devices in distant places in a building. A possible solution is the HomePlug repeater we propose in this paper. We show that it is impossible to develop a repeater at the physical layer, so we have developed it at medium access control (MAC) level. Its main distinctive features are transparency (no planning is necessary) and availability (it is built from off-the-shelf hardware).

Diverse social applications rely on remote location of personal devices: house arrest tracker systems, remote monitoring of alcoholic persons, child locator devices and remote protection of victims of domestic abuse are some examples. However, existing personal location devices either depend on a fixed station (a domestic gateway) -thus limiting user mobility-, or include a full cell phone -thus increasing weight, cost and power consumption-. In this demonstration, we present a new system we have developed for the Galician regional government (Spain) to track domestic abusers and their victims. It consists of two units, namely a personal low-cost light microdevice (bracelet in the sequel) and a commercial cell phone. The latter acts as a mobile gateway, which the bracelet accesses via a PAN. By doing so, we benefit from the advantages of the two previous approaches: the small size of bracelets for fixed gateways and the full mobility of those including a full cell phone. Wide-area location capability may reside either in the bracelet (as a GPS modem) or in the mobile gateway (either as a GPS modem or via core network-assisted location). If the bracelet leaves mobile gateway PAN range, the latter alerts the user and/or sends an alarm to a remote monitoring station.

A practical real-time mobile auction system must fulfill diverse constraints. In Rodriguez-Hernandez P.S. et al. (2002), we described a mobile auction system implemented with 433 MHz band modems. Nowadays, that system has become a standard in the Galician fish markets, which include the most important fishing port in Europe, Vigo (Spain). Although our system has been performing satisfactorily for four years, it is obvious that new technologies such as Bluetooth and IEEE 802.11 have shaped the wireless market and deserve our attention. In this paper, we evaluate Bluetooth in the context of real-time mobile auctions. As a result, we propose a novel approach to implement mobile auction systems by exploiting the park mode in Bluetooth specifications, which may also be useful for other remote-command applications with hard real-time constraints