Interactive Outdoor Web-based Distance Learning Using Mobile Terminals

Outdoor learning provides an opportunity for direct learning experiences which can enrich the school curriculum in different subject areas, such as natural sciences, architecture visual arts and industrial/civil engineering. This experiencebased instruction can be effectively enhanced by computerbased learning environments by providing each student with a mobile device fully connected to the Internet and to its word-wide resources. Such one device can be used by a student to access customized information which may be related to the places that constitute the outdoor environment. In this paper, the general architecture of a mobile Webbased distance learning service for interactive outdoor learning is described, along with the guidelines which have led to its design. In addition, an evaluation exercise has been carried out in order to confirm the adequacy of the approach and to determine the future development of the system. INTRODUCTION Recent advances in telecommunication and network technologies are enabling new important real-time applications characterized by the keywords interactivity and multimedia [1]. One of those emerging real-time applications is represented by interactive distance learning. Traditionally, a distance learning service allows students to attend a lecture that is taking place at a remote location, providing them with the possibility to interact with the remote teacher, for example, by interrupting the lecture for asking some questions. From the communication standpoint, a distance learning service requires a sort of bidirectional transmission of audio and video between the instructor and the students, accompanied with additional educational material, such as still images, messages, appointment schedules, needed to organize and conduct the lecture. Moreover, the technical advances in the development of new mobile terminals, the increasing request of advanced wireless services and the wide success of the Internet are also making user mobility and ubiquity two key features for the information technology infrastructure of the near future [2]. In particular, the trend of integrating the Internet and the mobile telephony is revealed by the success of the WAP protocol [3] and, at least in Europe, this kind of integration technologies will be soon improved by the introduction of the future European mobile network infrastructure, known as UMTS (Universal Mobile Telecommunications Standard) [4]. Based on the considerations above, we may claim that it is becoming very important to design and develop new interactive Web-based distance learning applications that enable user mobility through the mixed use of mobile terminals and the Internet. Such those modern distance learning applications may offer mobile didactical services to the students thus allowing, for instance, outdoor learning experiences in scientific and technical educational fields. By using mobile technologies and adequate portable devices, the learning process can partially take place outside the classroom. The benefits of such one outdoor learning activity for both teachers and students may be summarized as follows: 1. additional resources are made available to teachers to carry out their teaching activity, and 2. students’ traditional experiences in the classroom may be enriched and complemented with real experiential knowledge obtained on-the-field. In essence, outdoor experiential activities can facilitate the construction of abstract concepts and enhance meaningful learning, providing for long-term awareness of the reality. Through outdoor based programs, students may gain a realization of their relationship to the real environment, which cannot be learned through abstract sources. Typical specific fields where the educational process may greatly benefit by (a mobile) technology that enables interactive outdoor distance learning are: 1. Industrial engineering: Guided visits to industrial plants may be organized with the help of mobile devices that allow students to directly inspect the production process, along with a prerecorded on-line help provided by mobile terminals. Moreover, Web-based mobile learning environments can also permit to the students to perform supervised laboratory activities in industrial environments. 2. Architecture/civil engineering/visual arts. The guided visit of cities, streets, buildings and museums may be conducted by students with the help of mobile devices, through which information about the architecture, the history and the urban planning may be provided. The mobile training system should operate either by offering a menu-based interface to allow the choice of the information required by the user or by directly providing the correct information on the basis of the student’s position during the visit. 3. Zoology, geology and other natural sciences. Moving across open areas may enable students to discover interesting things, while listening to appropriate explanations trough mobile devices. In addition, the mobile device can be also used to record and store the information to be used subsequently. Within this scenario, we have devised the general architecture of a mobile Web-based application that enables interactive outdoor multimedia learning activities. In this paper we illustrate such one Web-based distance learning service along with an evaluation exercise carried out to confirm the adequacy of the approach. The remainder of this paper is organized as follows. The next section describes the general architecture of our mobile Web-based distance learning service for interactive outdoor learning and its main components. Section 3 reports on different application requirements that have to be met in order to make the service effective. Finally, Section 4 concludes the paper by discussing future development of the proposed system. SYSTEM ARCHITECTURE To implement the above mentioned educational service for interactive outdoor learning, we propose an architecture based on the integration between software applications based on Web technology and mobile access network infrastructures. Two relevant problems come out from the attempt of integrating the best effort nature of the Internet with the mobile access infrastructure that is characterized by low bandwidth and unpredictable connection stability. On the one hand, a typical problem with the use of wireless technology is related to the typical low value of available bandwidth and the high latency that characterize the network access through mobile devices. This problem is typically exacerbated when streams of multimedia data that are usually provided by modern Web-based distance learning tools have to be transported by wireless networks and displayed by means of mobile devices. In essence, the downloading activity of massive amounts of multimedia educational material, which may include text, high definition images, sounds, digital audio and video may pose a very critical transmission problem to the mobile networked technology. On the other hand, Internet-based services may be often unavailable, while, if the mobile terminal can obtain its access to the network, then the wireless telecommunication network usually guarantees services availability with a very high rate. Hence, from this point of view, it is worth noticing that the design and the implementation of Internet-based services that satisfy the important requirements of reliability (i.e. capability of an application to correctly work in presence of specified faults) and responsiveness (i.e. capability of an application to be correctly work in an acceptable amount of time) are not trivial tasks. In order to circumvent the former problem mentioned previously (i.e. the difficulty of wireless network technology to transport complex multimedia educational data with a tolerable latency), we have decided to resort to the available technology. In particular, we have decided to adopt an inexpensive video conferencing system which is able to provide low quality video with a telephone-quality transmission of voice for supporting live lectures (such as, for example, the well known CuSeeMe and NetMeeting applications), coupled with the use of third-generation cellular telephone technologies (such as GPRS and UMTS) that are able to provide available bandwidth ranging from 115,000 bps to 2 Mbps. With respect to the latter problem we have mentioned (i.e. the scarce level of availability and responsiveness that traditional Internet-based services may offer) we have decide to design and implement our Webbased distance learning service by introducing and exploiting software redundancy, namely by replicating the service across a certain number of Web servers geographically distributed over the Internet. In this context, a typical approach to guarantee service responsiveness consists of dynamically binding the service client to the available server replica with the least congested connection. An approach recently proposed to implement such one adaptive downloading strategy at the Internet side amounts to the use of a software mechanism, called the Client-Centered Load Distribution (C2LD) mechanism [5]. With this particular mechanism, each client browser request of a given Web document is fragmented into a number of sub-requests for separate parts of the document. Each of these sub-requests is issued concurrently to a different available replica server. The mechanism periodically monitors the downloading performance of available replica servers and dynamically selects, at run-time, those replicas to which the client sub-requests can be sent, based on both the network congestion status and the replica servers workload. Summarizing, the general architecture of our proposed system, may be thought as constructed out of the following five components: 1) a set of replicated Web servers. The reliable provision of educational services is based on the use of a set of replicated servers that hold the educational material and respond to the requests issued by different users by means of the well-known HTTP protocol (augmented with the C2LD software mechanism). The geographical distribution of those replica servers across the Internet aims: i) at redirecting each client request towards the nearest set of replica servers that are able to guarantee a low latency in their response, and ii) at distributing and balancing the workload among different servers across the Internet. Needless to say, in order for the service to be correctly implemented, all the replicated Web servers must be maintained in a mutually consistent status; 2) the Internet. The Internet network, through the use of its application-level HTTP protocol, provides the transport of the educational information from the set of replicated servers and the computer gateways that are located at the interface between the two network communication infrastructures; 3) the gateway between the Internet and the mobile network. The interface between the Internet and the cellular network infrastructure is maintained at one or more application gateways where management policies and translation mechanisms are implemented that are able to translate data from one of two different network infrastructures to the other; 4) the mobile network infrastructure. It is owned by the telephone network carrier and may be thought of as constructed out of two different parts: a set of base stations that represent the access points for the cellular mobile terminals, and the so-called core network that is in charge of linking together all the base stations and of transporting the data. Different cellular network infrastructures and technologies may be in principle used and provided by different network carriers; 5) mobile terminals. They are owned by the final users that use them to obtain the access to the interactive outdoor Web-based distance learning service. Those mobile devices must be equipped with a special light-weight micro-browser (such as those implemented within the WAP technology). Such one micro-browser needs to have multimedia capabilities to perform the playout of digital audio and video data. BASE 1 BASE 2 BASE 3 BASE 4 Core Network Carrier II Core Network Carrier I Gateway 1 Gateway 2 Gateway 3 Gateway 4