Abstract Previous work has demonstrated the feasibility of Bluetooth Low Energy (BLE) as an alternative technology for data transfers in inter-vehicular communication (IVC) scenarios. Bluetooth 5.x core specifications enhance the trade-off between energy requirements, communication range and flexibility. In this paper, we aim to analyse the potential of Bluetooth 5 features for VANET applications, proposing a connectionless communication system. By means of field experiments, we evaluate long range and 2 × speed features, defining a set of communication scenarios. This allows us to test both Bluetooth 5.x range and application throughput. The evaluation includes experiments of V2I communications carried out under real highway traffic conditions. The experiments conducted demonstrate that communication ranges up to 300 m may be achieved depending on the communications scenario. The results also show how throughput degrades as the distance between devices increases. The results obtained are used to discuss future work, aimed at deeper analysing Bluetooth 5 features for VANET applications, completing the development of our prototype and evaluating VANET connectionless communications with the features included in the latest Bluetooth 5.2 specification.

Road accidents and safe driving are one of the main concerns of transportation systems and the companies that explore different solutions to reduce the accident rate. The most interesting option to achieve this goal is through an on-board training of professional drivers to apply safe driving techniques during their work activity. The purpose of this study is to analyze a monitoring system that is not limited to the real-time vehicle tracking but is also capable of monitoring and providing real-time feedback and in-vehicle training. We analyze the influence of different sociodemographic factors on driving behavior. The analyzed data correspond to an urban public transport company, obtained from a study performed on 246 drivers. The drivers received training based on a blended learning system with an on-board feedback device, accompanied by both theoretical and practical sessions. The driving behavior of each driver is obtained from the data gathered from the vehicles that allow us to characterize their driving patterns. The information related to safe driving is completed with a list of the records of road accidents. The results of the sociodemographic influence on driving behavior provide significant information, giving an elaborated classification of safety driving patterns in order to apply intelligent transportation systems.

Interest in energy cost saving and in global warming have persuaded transport companies to apply measures to reduce fuel consumption. Efficient driving is one of the most employed solutions as it allows savings in fuel consumption of around 10% with a minimal investment. The drawback is that efficient driving is a learning process, and it greatly depends on the drivers' behavior, which in turn is closely related to their motivation. If drivers are not really involved or after some time their interest decreases, efficiency improvements would disappear. Thus, an efficient driving program should make drivers' motivation one of the main targets. One option could be the implementation of reward programs. However, these should be based on a clear individual evaluation process, as an unfair system could lead to discomfort, complaints, and repudiation. In this paper, we propose an analytic system, based on the detection of efficient and inefficient behavioral patterns, to evaluate the individual driver's progression in efficient driving with the aim of being the basis of a reward program. The system receives relevant, driving related, vehicle information every 1.5 s, allowing a precise searching of patterns. It has been tested successfully in 16 bus companies, analyzing the performance of 880 professional drivers. To accurately illustrate the analytic process, three detailed driver analyses have been included as a case study. Results of this applied research on the eco-driving field show that the proposed system identifies efficient and inefficient actions that are used to fairly evaluate the drivers' performance.

The popularity of Interactive Digital Television (IDTV) applications has grown in recent years, playing a significant role in today’s society. This new type of television allows users to access interactive applications in order to look for information, for communication or educational purposes, or just for fun. Most of these applications require text entry and many users expect a user experience similar to that of computers. Although the most common device to interact with television is the conventional remote control, other devices available on the market may be used in this context. Thus, in this article we aim to evaluate and compare different text input methods for IDTV applications using devices alternative to conventional remote controls. We have carried out an empirical study with 52 participants. We analyze entry speeds, error rates, and subjective impressions for six different entry methods, taking into account the particular characteristics of the users. As devices we have used a full-sized keyboard, a palm-sized keyboard, a gyroscopic remote point-select, and a modified touchpad. The fastest method is the standard keyboard, but in an IDTV context many users report discomfort and problems under low lighting conditions. Also, error rates are considerably higher with both keyboards when modifier keys need to be used. The results obtained with the gyroscopic remote and the touchpad are similar. Nevertheless, while users complain about fatigue problems with the former, their feedback about the latter is very positive. We have also observed that age is a major factor affecting the performance of the users. We expect our results to contribute to the design of new text entry methods for IDTV.

Remote controls are especially problematic for writing text, something necessary in many interactive digital TV applications (IDTV). In the context of research aimed at finding effective entry methods for IDTV applications, an empirical investigation was carried out and is presented in this article. The study analyzed the errors committed by 82 users in an experiment in which they wrote 7,395 sentences. Several typing methods suitable for IDTV contexts were used for experimentation. There were 3,562 of the sentences that registered at least one error. These errors were classified and their main causes analyzed, the particular characteristics of the users taken into account. The results show that the most frequent errors are proximity mistakes in all the evaluated methods. They appear in between 13.75% and 32.31% of the sentences, depending on the input method. Also, age and background are major aspects affecting the number and type of mistakes. The results could be the basis of changes in the design of conventional remote controls or in the design of advanced techniques for error recognition and correction.

Nowadays there is a huge market emerging in the interactive digital TV realm. In this context, we need new and effective methods of user interaction, as the main interaction device is still the classical remote control. Remote controls are especially problematic when it comes to writing text, something needed in most applications. Thus, we have carried out an empirical investigation to find effective methods of text entry with remote controls. We analyze several methods by performing experiments based on a methodology in which a heterogeneous set of real users carries out several sequential tasks in an incremental process. We analyze entry speeds, error rates, learning profiles, and subjective impressions, taking into account the particular characteristics of the users. Our results show, for instance, that Multitap is a good method for simple texts. It is between 12% and 34% faster than the fastest virtual keyboard, depending on the age of the user. Nevertheless, when complex texts need to be written, virtual keyboards present the same or even better writing speeds (QWERTY is 13% faster) and with significant lower error rates (Multitap is 347% worse than QWERTY). We consider that our results are very interesting for researchers, designers of TV applications, and hardware vendors.

Video streaming is not possible between nodes in different partitions of a Mobile Ad-Hoc Network (MANET). However, ferry nodes can be used to deliver video in this environment. This service is helpful in some application scenarios, like emergencies. An important problem arises when the capacity offered by such a delay-tolerant network is not enough to deliver all the video produced. Then, video adaptation is necessary, but the network capacity is hard to estimate. Dynamic Temporal Scalability (DTS) is a novel technique to solve this problem. DTS schedules frames from a stream stored in a node adapting the frame rate to the available resources. The results of evaluating this technique show that the frame sequence delivered to the user is close to live video and has small quality variations. In addition, video quality scales with the available resources. Finally, the efficiency in the use of network resources is similar with DTS and the default scheduling technique, i.e., FIFO.

The development of the technologies behind Interactive Digital Television (IDTV) services has produced a new type of audience. Traditional viewers now become users as they may play an active role in front of the TV, for example, by choosing a video to be played on demand or by introducing text on an IDTV application. In these services, interactions need to be performed with a remote control, currently the main interaction device, or other devices such as keyboards or mice, which are not very popular in this environment. Nevertheless, although remote controls are essential tools for IDTV services, they are very limited when it comes to writing text. Thus, this study evaluated different alternatives to introduce text on an IDTV application with a remote control. A heterogeneous group of people was selected to write predefined sentences in Spanish in a test environment using three virtual keyboard layouts and the multitap mechanism. Their performance and subjective impressions reveal weaknesses and strengths of the evaluated methods. The article draws important conclusions about the usage of remote controls in IDTV applications, not only for the design of new applications but also for the research of new techniques to introduce text.

Using Mobile Ad-hoc Networks (MANETs) for audio and video transmission is very promising for application domains such as emergency and rescue. However, audio/video streaming services are not designed for such dynamic and unstable networks. The problems are even more important in so-called sparse MANETs where the node density is relatively low so that disconnections and network partitions are common. We have designed an architecture that combines MANET routing with caching and delay tolerant store-carry-forward operations in an overlay network to improve the quality of audio/video transmission over sparse MANETs. We have implemented a prototype to evaluate the architecture. The results from the experiments demonstrate that our system clearly outperforms simple client-server solutions when the network has temporal disconnections.

This paper presents the popularity analysis performed on the www.lne.es video-on-demand service, which is part of the digital version of one of the most important newspapers in Spain. Its most special characteristics are the wide range of subjects (events, music, culture, tourism, nature, sports, etc) and the type of contents offered (long life, seasonal, etc), which make it an interesting case study. The analysis pays attention to the influence of the subject and the video characteristics on the popularity. Moreover, the results are checked for short and long periods of time. This study has been performed thanks to a log database with more than 170,000 requests of almost 1000 videos stored over a period of 4 years.

A key issue in any system for distribution of continuous media-on-demand is the capacity of the system with regard to quality of the service specifications, that is, the number of simultaneous streams the system can provide until degradation of quality of reproduction and interactivity perceived by the users. This work presents the evaluation of interactive video-on-demand systems, with special attention to limitations caused by the video server. The evaluation is based on a set of metrics designed to determine the number of streams a video server can support under specific requirements of quality of the service as perceived by the users. To validate the utility of these metrics, a prototype of a news-on-demand service has been built and the load for this kind of systems has been characterised. In addition, a load generator which emulates the concurrent access of several users to the system has been built. The evaluation establishes the relationship between the video server limitations and the quality of the service perceived by the users.

Real-time distribution of continuous media on demand is a natural step in the evoluation of internet services. Here, we briefly present an interactive talks-on-demand service currently integrated in a digital newspaper. Low cost, high availability and high performance are features of the system supporting the service.