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Feasibility of using mobile devices in conducting laboratory sessions in distance education is studied. Integration issues of Short Message Service (SMS) to monitor and remotely control instruments of hardware-based online laboratory, designed using the National Instruments (NI) Laboratory Virtual Instrument Engineering Workbench (LabVIEW) development system and web services is reported. The scheme will enable students to conduct hardware experiments with mobile devices using SMS from anywhere and anytime.
Although distance education in various forms is now common, conducting real time remote-controlled laboratory experiments (laboratory sessions) in distance learning is still not available. The development of web-based online hardware laboratories for distance learners is vital for higher educational institutions offering courses in engineering and technology especially electrical, electronics, computers and physics. In a conventional laboratory class each student have only a few minutes of actual time operating equipment while remote access to the laboratory equipment provides more time to students to run the experiment and collect data which can significantly improve student learning. Increasing demands for strengthening the learning experience, it is important to have interactive learning sessions. The meaningful use of mobile technology for laboratory sessions not just can motivate learners to be more engaging and active in learning activities, but also can facilitate learners to achieve better performance. With the availability of Internet, innovative ways to expand educational opportunities are now becoming a reality [1-3]. As an online laboratory can be accessed and run from any location and at any time, it is expected to be utilized more than a conventional laboratory in the future.
Remote-controlled laboratories have been reported since the internet started to provide reliable data communications. However, most reports in the literature describe the technical implementation of the laboratory rather than detailed evaluation of student learning advantages [4-6]. Several implementations, such as Telelabs at the University of Western Australia (UWA) [7, 8], MIT i-Lab [9-12] and NETLab [13-18] are in regular operation for large classes of students. However, the technology does not seem to have been widely adopted. Remote laboratories need to be merged into global and in homogeneous e-learning platforms for wider applications.
Now-a-days, mobile devices have become the most conveniently used portable learning platform for various educational purposes [19-22]. However, their use in conducting laboratory experiments (online laboratory) is rare.
The learning applications and technologies via mobile devices have a great potential. Some of the advantages of conducting laboratory sessions through mobile learning are: (a) the mobile device (with internet access) cost is lower than the computers (PC) cost; (b) the access to the remote laboratory can be done from anywhere at any time (student need not be at home or in laboratory); (c) learning how to use a mobile phone is easier compared to a computer; and (d) almost every student owns a mobile phone. However, the disadvantages of mobile devices are the small size of the screen, limited keyboard functions, and lower processing capacities which make the development of online laboratories more challenging. Development of a remote laboratory management system (LMS) for internet-based engineering education is necessary. One main goal of an LMS is to manage learning resources in a platform-independent environment while providing remote access to experiment sessions. A generic framework is desirable to allow instructors to integrate remote laboratories into their courses and enable creation, distribution, and exchange of learning materials.
Short Message Service (SMS) is one of the most popular modes of communication service component of the mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line and mobile devices. Currently, SMS text messaging is the most widely used data application in the world, with an estimated 2.4 billion active users or 74% of all mobile phone subscribers. In this paper, we present a novel scheme for the integration of Short Message Service (SMS) to monitor and remotely control laboratory instruments of a hardware-based online laboratory  that has been developed using the National Instruments (NI) Laboratory Virtual Instrument Engineering Workbench (LabVIEW) development system and report the merits and demerits of such a system.
The remotely-controlled online laboratory developed by the IIT Kharagpur NETLab developer team has the following features. Briefly, the IIT Kharagpur NETLab is an online Microelectronics and VLSI Engineering Laboratory in which several experimental modules are included. The combination of LabVIEW software and Agilent hardware (4156C) for developing web-based remote semiconductor device characterization laboratory is demonstrated . The NETLab uses the following components:
Java server pages and Java servlets as the means to design web pages.
The back end consists of Oracle 10g. The Oracle Database (commonly referred to as Oracle RDBMS or simply Oracle) is a relational database management system (RDBMS) produced and marketed by Oracle Corporation.
This system uses JDBC connection to build a connection between the java interface and the database.
The Sun GlassFish Enterprise Server v2.1 is used as the application server that generates the web pages according to the user inputs. The Sun GlassFish Enterprise Server is a comprehensive support offering for GlassFish, the leading open-source and open community platform for building and deploying next-generation applications and services.
Each user need to register to get a username and a password as well as a profile stored in the database. The user has to login and select a particular experiment and proceed. Each experiment has the following features: a laboratory manual, description of the experiment, experimental procedure etc. As the system works in a batch mode, it distributes the time in slots and each user has to select and choose a particular time slot for performing the experiment. However, the experiment manuals etc. are available all the time. The student logs on to the system to gain access to the laboratory and gains full control of the laboratory hardware. The user can adjust experimental parameters or submit new commands in real time. When the duration of experiment time is over the link is broken with a warning. The user has limited number of chances to book and use the experiment. This is done to optimize the use of the resources. After performing the experiment the user need to upload a laboratory report and has to take part in a viva session for evaluation purposes. Each user can perform the experiment again if not completed in one session.
When students prepare to conduct an experiment at an on-site laboratory involving a unique experimental setup (i.e., one that cannot be duplicated for concurrent use by the entire class), they will first need to find an available time slot and then register for that time slot. This may require the time taken to carry out the experiment to be pre-estimated.
The scheduling system for online experiment described here also assumes that the students would finish the experiment within a limited time, just like they would do in an on-site laboratory. In NETLab each experiment is assigned a given time slot which the administrator thinks is enough for the experiment, keeping in view the speed of Internet and other network element. The workflow can be summarized as follows:
The learner select the experiment
The learner opens the scheduling Web page link in the experiment page
The system displays the scheduling interface for the next 15 days
The system displays the available time slots for the selected experiment in green color
The learner selects the date for carrying out the experiment in the scheduling interface
The learner selects a desired time slot from the available time slots and submits the request
The system saves the learner schedule information and updates the scheduling database
The system displays a confirmation of the schedule to the learner
The bipolar device characterization module of the NETLab makes use of a single instrument (Agilent 4156C) for the characterization of a bipolar junction transistor (BJT) involving five experiments sequentially. The complete range of semiconductor DC parameters can be quickly and accurately evaluated with 4156C stand-alone instrument. With the flexibility and power of LabVIEW, students can perform automated measurements to gain a deeper understanding of device performance. The Experiment Module for BJT characterization consists of the following experiments:
Static Collector Characteristics
Current gain vs. Collector Current
THE SMS BASED SERVICE
The SMS Gateway
An SMS gateway is a way of sending a text message with or without using a mobile (cell) phone. Specifically, it is a device or service offering SMS transit, transforming messages to mobile network traffic from other media, or vice versa, allowing transmission or receipt of SMS messages with or without the use of a mobile phone. Typical use of a gateway would be to forward simple e-mail to a mobile phone recipient.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Getting the format of input for experiments
In order to operate the laboratory equipment from remote, the users need first to send a SMS in a particular format. Before the session begins, it is assumed that the user knows the list of available experiment in the website. The list of experiment gives the names of experiment as well as the corresponding experiment number (expno). The user sends this number along with a keyword to request for the input format of the experiment of expno.
This SMS is received in the laboratory server via a gateway connected to a GSM modem. The SMS Server gets both the receiverââ‚¬â„¢s number and the sent message as string inputs. It then parses the string according to a predefined pattern. For example, simple syntax that has been used in this system is:
MVL GETF s1001
TCAD GETF BJTOUTPUT
where, MVL or TCAD indicates the laboratory code, GETF command asks the server to return a formatted instruction to the user and s1001 or BJTOUTPUT is the experiment number, the user wants to perform. Once the SMS server receives this SMS, it checks out the pattern of input for a particular experiment from the database and sends the information back to the user at the number stored previously (see Figure 2 & 3).
Requesting and performing the experiment
The user then sends another SMS in this particular format to the SMS server (see Figure 4). For example, a SMS may look like:
MVL <code>;<password>;<expno>;<start voltage>;<stop voltage>;<step voltage>;<frequency>
When the SMS Server receives this SMS, it parses the string to extract each field into an array of String. Then the request is forwarded to the NETLab server (see Figure 1). This is done by calling a web service that is running in NETLab. The parameters are passed to this web service.
The NETLab web service then performs a series of functions:
1. It checks if all the input parameters for the experiment have been mentioned
2. All the inputs are within the permissible limits (depending on the experiment, setup and permitted measuring conditions necessary for the safety of the equipment).
3. It checks if the user could be allowed to perform the experiment at that time or not. SMS based users are not required to book time previously. It depends on the status of the instrument, whether it is in use at the current time or not. If the instrument is available then it is given to the request.
After confirmation, the NETLab server issues a new request to the Instrument server with the input parameters. The request is basically another web service on the Instrument server. The Instrument server/controller perform the measurements with the required setup using LabVIEW programming and GPIB interface.
Figure 1. SMS-based Service Architecture in NETLab.After the experiment is complete it returns an XML file as the output, to the NETLab server. The NETLab server web service determines if the output data is in correct format i.e., whether the output data is readable or not. The XML data is parsed and saved in a text file with a particular system derived file name on the NETLab server. The name consists of the date, time, user name and experiment name. This ensures the uniqueness of the name of the file. Each output of the experiment performed by SMS is thus saved on the server.
Figure 2. Sending a format request for experiment - s1001
(in Nokia 2630)
Figure 3. Received format for experiment - s1001
(in Nokia 2630)
Figure 4. Sending a request for experiment - s1003
After the completion of the writing of file in the NETLab server, the NETLab web service returns another XML output to the SMS server containing the report of the experiment along with the filename.
The user is sent a notification SMS about the success of the performed experiment and the corresponding file name where the output data has been saved. The user can then check the output file in a PC at any time (see Figure 6).
In case any error occurs in the above mentioned steps, an error notification message is sent to the user. Following errors can happen in the system:
The user sends the inputs with some parameter missing.
The user sends inputs that are out of range of permissible values.
The instrument(s) in experiment may be engaged at the time.
Some safety measures need to be taken in order to prevent the misuse of the service. Since SMS is cheap, anyone can start sending multiple SMS to the server repeatedly in an interval of time. However since processing a request takes time and consumes resources, it is necessary that this does not happen.
To do this the server has to maintain a log of recently received request numbers. If any number is repeated in an interval of time the request will not be processed. Also no request from a number shall be entertained that is already in process.
Figure 5. Excerpts from the log of SMS GATEWAY sever side programCHARACTERISTICS OF THE
SMS BASED SERVICE
First let us see the feasibility of using an SMS based service. It is theoretically unreliable since the SMS may not reach the server at all. However with rising quality of service in the communication sector, the chances of messages being lost is less.
When an SMS message is sent to a recipient, it is expected that it will deliver to the handset within seconds. However, delivering an SMS is a relatively complex process, and an SMS Center (SMSC) has to take several measures to ensure a reliable service. An SMS may fail to deliver to a handset on its first delivery attempt for many reasons. Then it can perform many actions:
Re-send the SMS when handset is available: This occurs if any of the following is detected and notified to the SMSC
If a subscriber was out of network coverage, and then comes back into coverage.
If a subscriber handset was turned off or out of coverage for a long time.
If the handset experiences a temporary problem such as memory full.
Time-based retry schedule: An SMSC may attempt to deliver an SMS according to a timed schedule. The schedule that is used is usually dependent on the error that was received. Temporary errors such as communication failures would be retried more frequently, for example every minute for 5 minutes, then every 10 minutes for 1 hour, then every hour for 24 hours. Most carriers will retry for a few days, but there's usually no facility for notifying about failures. Longer lasting errors such as absent-subscriber may be retried every hour for 7 days.
In short there is no abslotute guarantee of reliability or timeliness about send and receiving an SMS but the vast majority of messages get through and very quickly. Also with a delivary notification system it is easier to confirm whether a message has been dispatched or not. Hence it is feasible to use SMS to conduct Laboratry experiment repomtely. Now let us see some of the advantages and disadvantages of the SMS based Service:
Advantages of SMS
There are several advantages:
SMS can be used from anywhere.
It is cheap and easily accessible.
It is very useful in India and other developing countries. It does not have any special hardware requirement than an ordinary phone (Rs 2000) on the user side.
Figure 6 Reply SMS for experiment - s1003
Disadvantages of SMS
There are a few disadvantages also:
It is very slow (around 10 SMS can be processed per minute). This can be solved by establishing parallel SMS server outlets for each laboratory.
It is difficult to display result to user directly. There can be two types of output from an experiment ââ‚¬"
Small data sets where the outputs are less and calculated from a large dataset. For e.g. TCAD experiments
Large data sets where the output consists of raw measured data which can consist of hundreds of records.
Although it is possible to create some kind of graph from the data set by extensive sampling. Then this graph can be sent to the user for verification. However Single data i.e. TCAD thing can be shown directly.
SMS cannot give the users the actual feeling of using an instrument in the laboratory but it is instead a good and easy way to use the instrument from remote location.
Feasibility of using mobile devices in conducting laboratory sessions in distance education is demonstrated. Integration issues of Short Message Service (SMS) to monitor and remotely control instruments of hardware-based online laboratories are discussed. Conversion of a PC-based remote-controlled online laboratory to mobile device control is shown. Although SMS would add greater mobility and flexibility for the laboratory user, but it is still a slow process in terms of read and reply to each of the requesting SMS.