Research Article Attendance Check System and ...downloads.hindawi.com/journals/ijdsn/2015/508698.pdfAttendance Check System and Implementation for Wi-Fi Networks Supporting Unlimited

Research ArticleAttendance Check System and Implementation forWi-Fi Networks Supporting Unlimited Number ofConcurrent Connections

Min Choi1 Jong-Hyuk Park2 and Gangman Yi3

1Department of Information and Communication Engineering Chungbuk National University 52 Naesudong-roHeungdeok-gu Cheongju Chungbuk 361-763 Republic of Korea2Department of Computer Engineering Seoul National University of Science and Technology 232 Gongneung-roNowon-gu Seoul 139-743 Republic of Korea3Department of Computer Engineering Gangneung-Wonju National University 150 Nomwon-ro Heungeop-myeonWonju-si Gangwon-do 220-711 Republic of Korea

Correspondence should be addressed to Gangman Yi gangmancsgwnuackr

Received 14 October 2014 Accepted 18 December 2014

Academic Editor Neil Y Yen

Copyright copy 2015 Min Choi et alThis is an open access article distributed under theCreativeCommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In the past we used to call the name of members for the purpose of attendance checking by managers (or instructors) They verifythe identity of memberrsquos participation by human recognition using facial and voice matching This approach is time-consumingbecause the number of members is getting increased Moreover theymay have to recheck any of the studentsrsquo presence at the end ofthe period manually In this research we offer a convenient novel attendance checking method to take advantage of Wi-Fi 80211xtechnology Our application initiates AP mode Wi-Fi service for checking attendance of users in which a token is generated onlyto a person who is close to a manager If a member has the token the smart application of the member will connect and report toattendance server Otherwise the smart application of the member will report to the server that the usersstudents are not near themanager By this way managersinstructors can easily check the memberrsquos attendance In addition this research proposes a novelconcept that unlimited number of devices can be supported We make use of Wi-Fi scan (rather than connect) to the managerrsquos APenabled smart devices resulting in an enhanced scalability

1 Introduction

Checking studentsrsquo attendance in schools universities kin-dergartens and travel agencies is a time consuming processbecause the instructor has to call each person by personwhenthe number of studentsusers are big So instructorsleadershave to consumemore time for students to check attendanceI suggest a smartphone based attendancemanagement systemusing Wi-Fi signals In this research studentsusers do nothave to recognize or tag such a RFID card to reader Atten-dance is automatically checked only if I have the smartphoneI aggregate statistics about absences lateness and attendanceautomatically

In the past we used to call the name of members(including students travelers and children) for the purposeof attendance checking by managers (teachers leaders and

employer etc) Usually instructors verify the identity ofstudents by human with facial and voice recognition Thematching along with facial and voice recognition will be doneagainst the presence status of the studentThe instructor mayrecheck any of the studentrsquos presence during the lecture bymanually checking the updated attendance list that shows thematchingweights during or after class Recently an automaticattendance checking by using a RF communication is widelyused However if the RF card is faulty or studentsusers donot get the RF card this RF based attendance checking cannotwork properly Moreover it is not enough to cover the entireareas of a certain lecture room forNear FieldCommunicationand Bluetooth technologies

To resolve these problems we offer a novel attendancechecking method by convenient and correct way to take

Hindawi Publishing CorporationInternational Journal of Distributed Sensor NetworksVolume 2015 Article ID 508698 10 pageshttpdxdoiorg1011552015508698

2 International Journal of Distributed Sensor Networks

Kindergartens Travel agencies

Taking a rest or picture in rest area of highway Lecture room

Figure 1 The necessity of Wi-Fi attendance checking system

advantage of the Wi-Fi 80211x technology on smart mobiledevices In this research managers initiate AP mode Wi-Fiservice for checking attendance of users Whereas managershave to install a manager version smart application users canoptionally install a client version smart application only if itis necessary for the users to use add-on functionalities Man-agerrsquos smart device is connected to the studentrsquos smart deviceat all timesTherefore the manager can decide whether a stu-dent is close to themanager during a specified period of time

(a) This method prevents the student from leaving theclassroom right after checking a present or fromanswering the call for checking instead of other stu-dents

(b) During outdoor activities it can automatically checkperiodically whether children and infants are close toleader (instructor or teacher etc) since the leadermust move together with children or infants duringoutside activities Otherwise the children or infantsmay get hurt from car accidents

(c) When groups of tourists move (for purposes suchas tourism and business trips) somewhere using acharter bus a tour guide can easily check whether allthe people are on board the vehicle

Figure 1 shows the necessity of Wi-Fi attendance checkingsystem When you move a large number of members groupby a group of transport (charter bus etc) for purposes such astravel tourism or business trips youneed to stopmoving andthen start moving again repetitively Here we take advantageof this system because we can easily check all members (only

if predefined) whether or not the instructorsmanagers areeasily able to check get in touch quickly by displaying thesmartphone leader in instant contact list of members and donot ride the present invention relates to using a Wi-Fi to beautomated attendance management method

In order to verify that a user is within a defined distanceto manager beacon signal alive message or packet areinterchanged by communication at regular time intervals(eg 10 seconds and 60 seconds) periodically with each otherFor the purpose of checking the attendance of the members(students etc) students have to connect to instructorrsquossmartphone (not necessary only for smartphone it may beany embedded systems) which is Wi-Fi AP enabled systemIn addition this system supports that unlimited number ofdevices may be connected We just make use of Wi-Fi scanto the managerrsquos AP enabled smart devices rather than beconnected to the manager [1 2]

The rest of this paper is organized as follows Section 2describes related works Section 3 explores the architectureand process of our E-authentication system and presents theexperimental results using our system Finally we concludeand summarize our work in Section 4

2 Background and Related Works

Before we go into more detail we first review the backgroundknowledge and related researches done previously Thereare many proposals for Automatic Attendance Systems inthe literature and in the market Most of them do focus onapplications to be installed on the lecturer device whether

International Journal of Distributed Sensor Networks 3

Attendance check module

Network connectionmanager

Embedded DNS server

Embedded web server

Smart device operating system

Wi-Fi MAC Bluetooth NFC

Smart device application

(a)

Application for student

version

DB

Server

Application for

professor version

(b)

Figure 2 Overall system architecture

a smartphone or a laptop In this section we will mentionbriefly few of these proposals

Reference [3] proposes software to be installed in theinstructorrsquos mobile telephone It enables it to query studentsrsquomobile telephone via Bluetooth connection and throughtransfer of studentsrsquo mobile telephonesrsquo media access control(MAC) addresses to the instructorrsquos mobile telephone pres-ence of the student can be confirmed

In [4] there is another example on a proposal thatuses real time face detection algorithms integrated on anexisting learningmanagement system (LMS) It automaticallydetects and registers students attending a lecture The systemrepresents a supplemental tool for instructors combiningalgorithms used in machine learning with adaptive methodsused to track facial changes during a longer period of time

On the other hand in [5] the proposal uses fingerprintverification technique They propose a system in which fin-gerprint verification is done by using extraction of minutiaetechnique and the system that automates the whole processof taking attendance Since biometrics are concernedwith themeasurements of unique human physiological or behavioralcharacteristics the technology has been used to verify theidentity of users It is becoming critical to be able to monitorthe presence of the authenticated user throughout a session

Thus another proposal [6] discusses a prototype systemthat uses facial recognition technology to monitor authen-ticated user or students A neural network-based algorithmwas implemented to carry out face detection and an eigenfacemethod was employed to perform facial recognition Theexperimental results demonstrate the feasibility of near-real-time continuous user verification for high-level securityinformation systems [6]

3 Wi-Fi Attendance CheckingSystem Architecture

31 Overall Architecture The overall system architectureof our Wi-Fi attendance checking system is as shown inFigure 2Our system consists of two subsystems smart deviceapplication and smart device operating systems Smart deviceoperating system is to check the studentuserrsquos attendanceby sensing the Wi-Fi signals The attendance managementsystem comprised of RESTful open API web service and

smartphoneweb client applications The implementationdetails are described in Section 4

As shown in the left side of Figure 2 our platform sup-ports not only Wi-Fi but also Bluetooth and near field com-munication (NFC) protocols for checking attendance fromstudentsusers The smart phonedevice operating systemwill schedule and allocate system resources such as CPUhardware and software into the required modulesprocessesOn top of the start phonedevice operating system thesmart phonedevice application works on checking atten-dance by Wi-Fi consisting of attendance management partnetwork connection management part embedded DNSserver (optional) and embedded web server (optional) Inthe right side of Figure 2 Wi-Fi using the automatic atten-dance management process will be described Usersstudentsconnect to server and the managerinstructor and man-agerinstructor also connects to server If the user has ldquotokenrdquothe userstudent smart application will report to the serverthat the usersstudents are attended the class If the user hasnot ldquotokenrdquo the userstudent smart application will report tothe server that the usersstudents are not attending the class

Moreover the system requires a setup in priori by themanagerinstructor through its server module to configurethe classtour information for advertising the titlepurposeof the tour program or the class The managerinstructormay choose to encrypt this code depending on the level ofprotection needed This will include the following informa-tion course or tour id date and beginning time of the lec-turestours managerinstructor name and some passcode (ifnecessary) This can be added or modified at any time beforeclasstour During the classtour or at its beginning theman-agerinstructor leverages the usersstudents to participatethe classtour from their signed-up classestoursprogramsthrough clicking on their participation button From then onthe students can then be tracked by their location using thesystem as shown in Figure 3

As shown in Figure 3 the smart phonedevice of userstudent communicates Wi-Fi primitives (such as beaconsignals alivemessages or packets) which are interchanged bythe communication at regular time intervals (eg 10 secondsand 60 seconds) For the purpose of checking the attendanceof the members (students etc) students have to connect(not ldquoconnectrdquo strictly just ldquoscanrdquo) instructorrsquos smartphone


A cycle

1998400

1998400998400

1 2

Figure 3 Communication in attendance check application betweeninstructors and students

(not necessary only for smartphone it may be any embeddedsystems) which is Wi-Fi AP enabled system

The server then has to run the identity check on theregistered group membersusersstudents This is done bycomparing the Wi-Fi MAC address which is sent from theuserrsquos smart phonedevice and that is stored on file for theusersstudent in priori To this end every traveler or studentshould register their information before departing their tripor at the beginning of the lecture respectively At that timethe Wi-Fi MAC address of the travelersusers is transferredand stored to the server A matching MAC address willbe added to the attendance sheet so the instructor couldperform a manual check either during the lecture or after thelecture The identity check can be done once the attendanceregistration transaction is received or at a later scheduledtime We recommend to perform the identity check of astudent at the beginning of the lecture but if the number ofstudents and concurrent lectures are large compared to thespeed of the server then the job could be performed say at arandom instant in the second half of the lectureThe purposeof this job is to allow the instructor to check the results of theidentity check before the end of the lecture if heshe wishesto do so

As shown in Figure 2 the system comprising of twoapplications on smart phonedevices (manager and user) adatabase server and a web application server [7] Now wetake a look at the operation of the smart phonedevice appli-cations These applications are the parts that studentsusersusually install on their smart phones These are standaloneapplications that communicate with the web applicationserver for attendance checking The user detection willbe achieved by scanning through the Wi-Fi network andcommunication will be through the 3G4G internet

Figure 4 describes the algorithm of managerinstructorand userstudent application in the left side and right sideof the Figure respectively As shown in the left side ofFigure 4 manager application activates the Wi-Fi AP modeat the beginning of the application Then the bottom half

of the left side of Figure 4 represents attendance recordingprocess if web server is embedded in the instructorrsquos smartdevices or APs As mentioned in early part of this Section 31our attendance check application may have an embeddedweb server and an embedded DNS server The web serveris necessary within the system since the usersstudentshave to connect to the instructors smart devices or APsthroughWi-Fi But there is no problem even if a web serveris not embedded This is because the managerinstructionapplication can connect and report the attendance checkresult to the third party web application server through3G4G networks not to the managerinstruction applicationitselfThis is the enhanced version of the attendance checkingwith supporting unlimited concurrent connections whichwill be described in Section 32

Now we are going to discuss the distance estimationmethod from the signal strength Fortunately we can applya well-known signal propagation model which maps RSSIvalue to distance estimates [8] We exploit the most widelyused signal propagation model of the log-normal shadowingmodel as follows

RSSI (119889) = 119875119905minus PL (119889

0) minus 10 120578 log

10

119889

1198890

+ 119883120590 (1)

where 119875119905is the transmit power PL(119889

0) is the path loss for

a reference distance 1198890 120578 is the path loss exponent and

119883120590is a Gaussian random variable with zero mean and 1205902

variance which models the random variation of the RSSIvalue Various transmitters behave differently evenwhen theyare configured exactly in the sameway In practice thismeansthat when a transmitter is configured to send packets at apower level of 119889 dBm then the transmitter will send thesepackets at a power level that is very close to 119889 dBm but notnecessarily exactly equal to 119889 dBmThis can alter the receivedsignal strength indication and thus it can lead to inaccuratedistance estimation [8] However it does not matter in thisresearch because we do not focus on measuring the distanceexactly from the RSSI value but we mainly focus on justdetecting the SSID signal for checking whether userstudentis close to an instructormanager Wi-Fi attendance checkingsystem needs not check the distance between instructor andstudents but only check whether the students are close to theinstructor

32 System Approaches for Supporting Unlimited Number ofConcurrent Connections Maximum numbers of Wi-Fi con-nections for a single Wi-Fi depend on the devices We haveto deal with interference between those 60 radios all trying tobroadcast Engineers of planning an 80211b wireless networknormally say that the rule of thumb was about 10ndash12 clientsper AP for best performance you can probably move thatup to 20ndash25 (pure off the cuff number) with todayrsquos newertechnologies But that still does not get you to 60

This is because bandwidth we are actually contending foris not the back end ethernet link but the wireless link speedSo on a 54mbps Wi-Fi AP you would be contending for the54mbps At 60 clients that would be about 900 kbps eachnot counting TCP overhead counting TCP overhead you arealready down to sim720 kbps [9]


Start

Initialization

Enable Wi-Fi

Enable Wi-Fi AP mode

Connection

Set configuration of Wi-Fi gateway

Checkattendance

Record attendance

Absents notification

End

Periodically checkNo

No

(a)

Start

Initialization

Enable Wi-Fi

Connection request

Attendance notification

End

Periodically check

No

(b)

Figure 4 Flow chart of attendance check for smart applications

AP

AP

Client

Client

Client

Client

Client

Client AP

Client

Client

AP

Figure 5 System architecture for supporting unlimited concurrentconnections

In order to overwhelm this limitation this research pro-poses the Wi-Fi attendance check which supports unlimitednumber of concurrent connections That means it supportsthat unlimited number of devices may be connected sothat unlimited number of usersstudents can connect to themanagers AP and checkconfirm the attendance To this endwe make use of just Wi-Fi scan to the managerrsquos AP enabledsmart devices rather than be connected to the manager asshown in Figure 5

Figure 5 shows our key idea that the Wi-Fi attendancecheck system supports unlimited number of concurrent con-nections [10] A leadermanager has an access point (AP) as

shown in the right side of Figure 5 We depicted the coverageof AP as a solid line of circle in the right side of Figure 5In order to verify that a user is within a defined distanceto manager the smart device of leaderinstructorsmanagerhas to check the smart device of childrenstudentsusersperiodically So the communicate Wi-Fi primitive signals(such as beacon signals alive messages or packets) areinterchanged by communication at regular time intervals(eg 10 seconds and 60 seconds) For the purpose of checkingthe attendance of the members (students etc) students haveto connect (not ldquoconnectrdquo strictly just ldquoscanrdquo) instructorrsquossmartphone (not necessary only for smartphone it may beany embedded systems) which is Wi-Fi AP enabled system

Manager smart application initializes the device It alsosetsWi-Fi module to operate as an access point- (AP-) modeso that Wi-Fi beacon signal is to be broadcasted resultingin that user devices can detect the Wi-Fi beacon signal Butin this research we do not require for the user device tofully connect to the manager AP because there are limitson maximum number of Wi-Fi connections for a single Wi-Fi For this purpose manager device can utilize access pointmode tethered mode and Wi-Fi direct connection modeand so on By this way the user node which detects themanager APrsquos SSID will be called a client node having aldquotokenrdquo So we can reasonably infer that the applicationshaving the ldquotokenrdquo must be close to manager AP Thusthe user applications having the tokens can only report thefact that they attended the class or that they are near theinstructors This attendance information will be saved toserver by RESTful open api web service [9]

The most advantage is that coverage of Wi-Fi is big-ger than any wireless networks such as Bluetooth and NFC


Application for students

Initialize and enable Wi-Fi

Connect to server

Send the scan result

Get attendance result

Start

Get class information

Scan Wi-Fi

End

Initialization

Start

Application for instructors

Listen

Start

Server application

Enable Wi-Fi

Send class information

Get the scan result

Notification attendance result

Figure 6 The core flow chart of attendance checking supportingunlimited concurrent connections

Usually the size of big lecture room is larger than 50msim100m Sowireless networks such asNFCorBluetooth cannotcover all the attendance of candidatesstudents in the roomby a single access point But the Wi-Fi network coverage isenough to cover all the area of the large lecture room

4 System Implementation and Evaluation

Up to now we described the system architecture for higherscalability From now on we are going to illustrate systemimplementation and evaluation in detail Each communica-tion in Figure 6 between attendance server and userstudentcan be implemented by RESTful open API interface orgeneral HTTP web interface [11ndash13] The reason why weprovide both interfaces is because we try to realize theplatform independence by supporting as webmobile appli-cation and general PC applications simultaneously Oneof our key approaches in attendance server system is thatfunction of user discrimination and validation during atten-dance checking depend on a request To this end the userclient generates MD5 hash fingerprint using MAC addressand SSID and uploads these information onto server Inthis research we implemented the user client prototypeon Android 43 operating system by smartphone mobileapplication as depicted in Figure 8 The server runs onApache Tomcat 81 web application server We make use ofJERSEY 18 server and Spring Framework 31 for REST openAPI [14ndash17] based attendance server implementation SpringFramework provides an API so that developers may extendSpring to suit their needs We make use of both Tomcat andSpring in order to implement our systems We constructed4 node Linux clusters of Core i5 machines each with 4GRAMThemachines are connected by network and managedby giga-bit ethernet interconnection network as shown inFigure 7

(1) Token Generation (Instructor AP harr User) User firstscans nearby Wi-Fi APs If the userstudent finds out

a designated AP then a user application of userstudent will generate a MD5 hash fingerprint TheMD5 hash fingerprint will be stored somewhere inuserrsquos smart device We call this MD5 hash ldquotokenrdquoThe reason why we have to generate the MD5 ratherthan using only the raw data of MAC address andSSID is because exposing the raw data only in URL isnot appropriate for security concerns If only the rawMAC address and SSID are exposed in RESTful webservice URL malicious userstudent can manuallyadjust the information to answer the roll for anotherstudent skipping the class In order to avoid suchthreat using both raw data andMD5 hash fingerprintrather than using only the raw information is betterin terms of system protection

(2) Attendance CheckUpload with Token (Userharr Atten-dance Server) It is used to upload a token into serverplatform This is to store a token into server (MD5hash fingerprint) which is generated from SSID andMAC address SSID comes from Wi-Fi access pointwhich is used to identify whether a studentuser isclose to themanager during a specified period of timeMD5hash fingerprintwas already generated using thetoken and userrsquos MAC address The reason why theMD5 should be utilized during attendance checkingis to protect duplicated attendance check trial forstudents skipping class using the same device if astudentuser tries tomaliciously check the attendanceby answering the roll for another skipping student

(3) Attendance Inquiry (Either Instructor harr AttendanceServer or User harr Attendance Server) It is used tocheck attendance record from database If a userstudent wants to check hisher attendance recordthen the user can inquire to attendance server withhisher identification for example MAC addressThen attendance server can provide the results tovalidated user with the identification

As a result a user only has to keep both of the MD5 finger-print file consisting of MAC address of the user and SSID ofan instructorrsquos AP then a server can check and validate theattendance request afterwards especially on a specific timeand a specific web site When someone needs authenticationfor a portion of the snapshot screen it is also possible onour system User can drag the region using a mouse fromthe captured screen Then authenticationvalidation will bestarted additionally through generating the MD5 hash byattendance servers using the submitted MAC address andSSID from users Then the attendance server compares therequested MD5 and newly generated MD5 data It makes adecision of data integrity if they are the same or not

In this section we provide experimental result for theattendance checking system We have implemented the Wi-Fi attendance checking application onAndroid operating sys-tem RESTweb service is one of themost convenientmethodsfor accessing information through internet [18] Usuallya smartphone application needs information from severalsources of (one or more) REST web services In this exper-iment we adopt the Apache Tomcat 70 as a web application


In

Sink

OutIn

A

Web application server(Tomcat Apache)

OutIn

A

DB serverOutIn

A

REST open API server (JERSEY)OutIn

A

Instructormanager(inside the Wi-Fi AP area)

Usersstudents

A


Usersstudents(outside the Wi-Fi AP area)

Usersstudents(inside the Wi-Fi AP area)

Wi-AP coverage

Figure 7 Evaluation model

Figure 8 Screenshots of usertravelerstudent client application


Table 1 Comparison of instruction AP internals in reachable or not reachable areas from 3G4G networks

Areas reachable 3G4G network(unlimited concurrent connection supported version) Areas unable to reach 3G4G networks

Number of concurrent connections Unlimited Depending on APrsquos performance

Implementation difference 3G4G network required to report the attendance checkresult

Web server and DNS server embedding required

Where to use Office university shool Urban areas or foreign countries

Purpose Attendance check in school university orbusinessoffice

Tour guide or group membermovement

server and Spring 30 for REST Open API Service Provideras server Apache Tomcat is open software with Java Servletand JavaServer Pages technologies Apache Tomcat powersnumerous large-scale web applications across a diverse rangeof industries and organizations Spring Framework is theopen source JAX-RS (JSR 311) Reference Implementation[14] for building RESTful Web services Figure 7 shows anoverview of our system architecture Spring Framework isto manage web services instead of web so as to provideweb server maintenance service especially compositiondeployment and management Requests traverse via the newincoming node and are received by the ldquoInrdquo represented bythe components at the left top of Figure 7 Our system modelis a sort of open queueing network that has external arrivalsand departuresThe requests enter the system at ldquoInrdquo and exitat ldquoSinkrdquo of attendance server system respectively

Prior to evaluating the performance in detail we presenta model of system model as shown in Figure 7 The systemis composed of three components (1) userstudents (2)instruction nodes (Aps) and (3) web application server (4)DB server and (5) REST open API server As shown inFigure 7 there are a number of components (nodes) compris-ing of several queues A request may receive service at one ormore queues before exiting from the system In the evaluationmodel jobs departing from Apache Web Server arrive atanother queue (eg the REST Server Farm from B1 to B4)

All requests submitted must first pass through the webserver for providing HTTP service before moving on to theREST web servers Jersey Requests arrive at the web server atan average rate of 1000sec to 15000sec as shown in Table 1To handle the load the REST web server components mayhave several parallel cloud or cluster architectures The num-ber of requests in the system varies with time In analyzingan open system we assume that the throughput is known (tobe equal to the arrival rate) and we also assume that thereis no probability of incomplete transfer in this system sothere is no retrial path to go back to Hadoop clusters Theinitialization process for the request is done at the schedulerThen the job proceeds to the component Spring Frameworkdepending on the type of the request A request may receiveservice at one or more queues before exiting from the systemA job departing from userstudenttraveler arrives from adedicated node for JERSEY and Spring Framework for RESTweb service All jobs submittedmust first pass through the jobschedulertracker for determining whether it is REST openAPI request Requests arrive at the web server at an averagerate of 1000sec to 15000sec Traffic intensity is calculated by

the arrival rate over the service rate that means how fast theincoming traffic are serviced on the server The key featureof our design is to separate the JERSEY web server onto adedicated node

Requests arrive at the web server A with frequency ldquoInrdquoThe initialization process for the request is done at nodeA Then the request proceeds to the component dependingon the type of the request if the request is for a RESTopen API it goes to the JERSEY or Spring 30 server Ifthe request is for just HTTP web pages then it goes tothe Apache Tomcat servers The web requests traverse viaApache Tomcat and DB server They are finally collected tothe Sink node represented by the components at the rightbottom of Figure 7 Our system model is a sort of openqueueing network that has external arrivals and departuresThe requests enter the system at ldquoInrdquo and exit at ldquoSinkrdquoThe number of requests in the system varies with time Inanalyzing an open system we assume that the throughput isknown (to be equal to the arrival rate) and we also assumethat there is no probability of incomplete transfer in thissystem so there is no retrial path to go back to node A Nowthe CPU components of recent smartphones can have morethan one CPU known as dual-core or quad-core Howeverwe assume that smart mobile device in this research hassingle-core CPU

Figure 9 shows the performance evaluation of this Wi-Fiattendance system as increasing number of servers 119883-axisrepresents the number of servers 119884-axis of the left and rightsides of Figure 9 describes the number of members refusedand the number of members processed respectively Thenumber of members turned away from the servers is gettingdecreased because the number of servers is increasing At thesame time we can see that the number of members processedcan be scalable as the number of server increases As thenumber of server node increases the total processing time oneach server decreases On this multiple server environmentthe identity verification task are distributed and computedconcurrently Since server nodes distribute the same amountsof data to all participant nodes the execution times arealmost the same on every server And the final executiontime contains more time such as communication overheadfork-join overhead processing overhead on mobile devicesHowever the computation power in servers of data centeris significantly better than the power in a single server Thetotal execution time will be improved if identify verifica-tion workloads are well balanced among various computingnodesThis achieves server scalability through the distributed


00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)

Figure 9 Time number of refused and processed members as increasing number of servers

0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)

Number of studentsmembersemployees in the system queue

Figure 10 Distribution of percentage of time depending on thequeue numbers on low arrival ratesec

01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)


Figure 11 Distribution of percentage of time depending on thequeue numbers on high arrival ratesec

processing As shown in these experiments there are nolimits of concurrent usersmembers who are gathered in thesame or near location

Figures 10 and 11 show the distribution of percentageof time depending on the queue numbers on arrival ratesFigure 10 depicts the distribution when the arrival rate is lowwhereas Figure 11 shows the distribution when the arrivalrate is high This graph describes Higher arrival rate occurswhen more studentsuserstravelers exists within a desig-nated area or close to an instructor whereas lower arrival rate

comes from the situation that less studentsuserstravelers arecrowded within a specified area or close to an instructor Asshown in Figure 10 lower arrival rate leverages the numberof queue to temporarily stay in the small number of queueentries for example 3 or 6However higher arrival rate leavesthe number of queue to constantly stay in the state of largenumber of queue entries for example more than 9

5 Conclusion

With the spread of IT technologies we offer a novel atten-dance checking method by convenient and correct way totake advantage of the Wi-Fi 80211x technology on smartmobile devices In this research managers initiate AP modeWi-Fi service for checking attendance of users The keyalgorithm in this research is as follows A ldquotokenrdquo is generatedonly to a person who is closed to a manager (or instructor) Ifa member has the ldquotokenrdquo a smart application of the member(or student) will connect and report to the server that theusersstudents are attended the class or near the manager Ifthe member does not have the ldquotokenrdquo the smart applicationofmemberwill report to the server that the usersstudents arenot attended the class or not near the manager By this wayinstructors can conveniently check the memberrsquos attendancewith a smart phone

In addition this research proposes a novel concept thatunlimited number of devices can be supported Engineers ofplanning an 80211b wireless network normally say the rule ofthumb was about 10ndash12 clients per AP for best performanceyou can probably move that up to 20ndash25 (pure off the cuffnumber) with todayrsquos newer technologies But that still doesnot get you to 60 In order to overwhelm this limitationthis research proposes the Wi-Fi attendance check whichsupports unlimited number of concurrent connections Thatmeans it supports that unlimited number of devices maybe connected so that unlimited number of usersstudentscan connect to the managers AP and checkconfirm theattendance To this end we make use of just Wi-Fi scanto the managerrsquos AP enabled smart devices rather than beconnected to the manager as shown in Figure 5 We utilizedWi-Fi scan (rather than connect) to themanagerrsquos AP enabledsmart devices resulting in an enhanced scalability


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work is supported by the Basic Science Research Pro-gram through the National Research Foundation of Koreafunded by the Ministry of Education Science and Tech-nology (NRF-2010-0025748 NRF-2013R1A1A2063006) thisresearch was supported by Gangneung-Wonju National Uni-versity

References

[1] M Syeful Islam M Rezaur Rahman A Roy M ImdadulIslam andM R Amin ldquoPerformance evaluation of finite queueswitching under two-dimensional MG1(m) trafficrdquo Journal ofInformation Processing Systems vol 7 no 4 pp 679ndash690 2011

[2] R Pan G Xu B Fu P Dolog Z Wang and M LeginusldquoImproving recommendations by the clustering of tag neigh-boursrdquo Journal of Convergence vol 3 no 1 pp 13ndash20 2012

[3] A C Murthy C Douglas M Konar et al ldquoArchitecture of nextgeneration apache hadoop mapreduce frameworkrdquo Tech Rep2013

[4] Processing and Loading Data from Amazon S3 to the VerticaAnalytic Database Amazon Web Service White Paper 2013

[5] Amazon Elastic MapReduce Developer Guide Amazon WebService 2009

[6] Getting StartedwithAmazonElasticMapReduce AmazonWebService 2009

[7] M T Goodrich D Nguyen O Ohrimenko et al ldquoEfficientverification of web-content searching through authenticatedweb crawlersrdquo in Proceedings of the International Conference onVery Large Databases (VLDB rsquo12) Istanbul Turkey August 2012

[8] D Lymberopoulos Q Lindsey and A Savvides ldquoAn empiricalcharacterization of radio signal strength variability in 3-D IEEE802154 networks usingmonopole antennasrdquo inWireless SensorNetworks vol 3868 of Lecture Notes in Computer Science pp326ndash341 Springer Berlin Germany 2006

[9] Zypher ldquoMaximum number of wifi connections for a singleWiFi routerrdquo 2010 httpserverfaultcom

[10] M Choi ldquoMethod and system for near field communicationusing wi-firdquo WO 2014025240 A1 PCTKR2013007230 Inter-national Patent 2014

[11] H Zhao and P Doshi ldquoTowards automated RESTful Webservice compositionrdquo in Proceedings of the IEEE InternationalConference on Web Services (ICWS rsquo09) pp 189ndash196 July 2009

[12] X Zhao E Liu G J Clapworthy N Ye and Y Lu ldquoRESTful webservice composition extracting a process model from linearlogic theorem provingrdquo in Proceedings of the 7th InternationalConference on Next Generation Web Services Practices (NWeSPrsquo11) pp 398ndash403 October 2011

[13] Z Li and L OrsquoBrien ldquoTowards effort estimation for web servicecompositions using classification matrixrdquo International Journalon Advances in Internet Technology vol 3 no 3-4 pp 245ndash2602010

[14] C Pautasso O Zimmermann and F Leymann ldquoRESTful webservices vs big web services making the right architectural

decisionrdquo in Proceedings of the 17th International World WideWeb Conference (WWW rsquo08) pp 805ndash814 Beijing China April2008

[15] R Alarcon EWilde and J Bellido ldquoHypermedia-driven restfulservice compositionrdquo in Service-Oriented Computing ICSOC2010 International Workshops PAASCWESOA SEE and SOC-LOG San Francisco CA USA December 7ndash10 Lecture Notes inComputer Science pp 111ndash120 Springer Berlin Germany 2011

[16] C Pautasso ldquoRESTful Web service composition with BPEL forRESTrdquo Data and Knowledge Engineering vol 68 no 9 pp 851ndash866 2009

[17] K Mahajan A Makroo and D Dahiya ldquoRound robin withserver affinity a VM load balancing algorithm for cloud basedinfrastructurerdquo Journal of Information Processing Systems vol 9no 3 pp 379ndash394 2013

[18] J Rao and X Su ldquoA survey of automated web service com-position methodsrdquo in Semantic Web Services and Web ProcessComposition pp 43ndash54 Springer 2004

International Journal of

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Active and Passive Electronic Components

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Submit your manuscripts athttpwwwhindawicom

VLSI Design



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Civil EngineeringAdvances in

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Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

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Navigation and Observation



DistributedSensor Networks



Kindergartens Travel agencies

Taking a rest or picture in rest area of highway Lecture room

Figure 1 The necessity of Wi-Fi attendance checking system

advantage of the Wi-Fi 80211x technology on smart mobiledevices In this research managers initiate AP mode Wi-Fiservice for checking attendance of users Whereas managershave to install a manager version smart application users canoptionally install a client version smart application only if itis necessary for the users to use add-on functionalities Man-agerrsquos smart device is connected to the studentrsquos smart deviceat all timesTherefore the manager can decide whether a stu-dent is close to themanager during a specified period of time

(a) This method prevents the student from leaving theclassroom right after checking a present or fromanswering the call for checking instead of other stu-dents

(b) During outdoor activities it can automatically checkperiodically whether children and infants are close toleader (instructor or teacher etc) since the leadermust move together with children or infants duringoutside activities Otherwise the children or infantsmay get hurt from car accidents

(c) When groups of tourists move (for purposes suchas tourism and business trips) somewhere using acharter bus a tour guide can easily check whether allthe people are on board the vehicle

Figure 1 shows the necessity of Wi-Fi attendance checkingsystem When you move a large number of members groupby a group of transport (charter bus etc) for purposes such astravel tourism or business trips youneed to stopmoving andthen start moving again repetitively Here we take advantageof this system because we can easily check all members (only

if predefined) whether or not the instructorsmanagers areeasily able to check get in touch quickly by displaying thesmartphone leader in instant contact list of members and donot ride the present invention relates to using a Wi-Fi to beautomated attendance management method

In order to verify that a user is within a defined distanceto manager beacon signal alive message or packet areinterchanged by communication at regular time intervals(eg 10 seconds and 60 seconds) periodically with each otherFor the purpose of checking the attendance of the members(students etc) students have to connect to instructorrsquossmartphone (not necessary only for smartphone it may beany embedded systems) which is Wi-Fi AP enabled systemIn addition this system supports that unlimited number ofdevices may be connected We just make use of Wi-Fi scanto the managerrsquos AP enabled smart devices rather than beconnected to the manager [1 2]

The rest of this paper is organized as follows Section 2describes related works Section 3 explores the architectureand process of our E-authentication system and presents theexperimental results using our system Finally we concludeand summarize our work in Section 4

2 Background and Related Works

Before we go into more detail we first review the backgroundknowledge and related researches done previously Thereare many proposals for Automatic Attendance Systems inthe literature and in the market Most of them do focus onapplications to be installed on the lecturer device whether




Embedded DNS server

Embedded web server




(a)


version

DB

Server

Application for

professor version

(b)














A cycle

1998400

1998400998400

1 2








RSSI (119889) = 119875119905minus PL (119889

0) minus 10 120578 log

10

119889

1198890

+ 119883120590 (1)









Start

Initialization

Enable Wi-Fi


Connection


Checkattendance

Record attendance


End


No

(a)

Start

Initialization

Enable Wi-Fi

Connection request


End

Periodically check

No

(b)


AP

AP

Client

Client

Client

Client

Client

Client AP

Client

Client

AP










Connect to server



Start


Scan Wi-Fi

End

Initialization

Start


Listen

Start

Server application

Enable Wi-Fi


Get the scan result













In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Embedded DNS server

Embedded web server




(a)


version

DB

Server

Application for

professor version

(b)














A cycle

1998400

1998400998400

1 2








RSSI (119889) = 119875119905minus PL (119889

0) minus 10 120578 log

10

119889

1198890

+ 119883120590 (1)









Start

Initialization

Enable Wi-Fi


Connection


Checkattendance

Record attendance


End


No

(a)

Start

Initialization

Enable Wi-Fi

Connection request


End

Periodically check

No

(b)


AP

AP

Client

Client

Client

Client

Client

Client AP

Client

Client

AP










Connect to server



Start


Scan Wi-Fi

End

Initialization

Start


Listen

Start

Server application

Enable Wi-Fi


Get the scan result













In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










A cycle

1998400

1998400998400

1 2








RSSI (119889) = 119875119905minus PL (119889

0) minus 10 120578 log

10

119889

1198890

+ 119883120590 (1)









Start

Initialization

Enable Wi-Fi


Connection


Checkattendance

Record attendance


End


No

(a)

Start

Initialization

Enable Wi-Fi

Connection request


End

Periodically check

No

(b)


AP

AP

Client

Client

Client

Client

Client

Client AP

Client

Client

AP










Connect to server



Start


Scan Wi-Fi

End

Initialization

Start


Listen

Start

Server application

Enable Wi-Fi


Get the scan result













In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Start

Initialization

Enable Wi-Fi


Connection


Checkattendance

Record attendance


End


No

(a)

Start

Initialization

Enable Wi-Fi

Connection request


End

Periodically check

No

(b)


AP

AP

Client

Client

Client

Client

Client

Client AP

Client

Client

AP










Connect to server



Start


Scan Wi-Fi

End

Initialization

Start


Listen

Start

Server application

Enable Wi-Fi


Get the scan result













In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Connect to server



Start


Scan Wi-Fi

End

Initialization

Start


Listen

Start

Server application

Enable Wi-Fi


Get the scan result













In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










In

Sink

OutIn

A


OutIn

A

DB serverOutIn

A


A


Usersstudents

A




Wi-AP coverage



















00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

























00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










00

200

400

600

800

1000

1200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

refu

sed

()

Number of servers

(a)

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Num

ber o

f mem

bers

pro

cess

ed

Number of servers

(b)


0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9

Tim

e (

)



01020304050607080

0 1 2 3 4 5 6 7 8 9 10

Tim

e (

)






5 Conclusion






Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Acknowledgments


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article Attendance Check System and ...downloads.hindawi.com/journals/ijdsn/2015/508698.pdfAttendance Check System and Implementation for Wi-Fi Networks Supporting Unlimited