A novel low cost telemedicine system using wireless MESH network

A NOVEL LOW COST TELEM

EDICINE

SYSTEM USING

WIRELESS MESH NETWORK

E

.

Supriyant o '

,

H.

Satria

2,

l.H.

Mulyadi

2

and E.H.

Putra

!

1

Faculty of Biomed ical

Engineerin g and

Health Science

2

Faculty of Electrical

Engineering

Univers iti Teknologi

Mal aysia

ABST RACT

Teiemedrcme pronuses an impr oveme nt of health CMe servicequalrty inrumI,urban. den seand mobileareas .In orde r10 implem ent the tclcmcd icinc in theseareas, a lo w cost rclcmcdicmc system with acceptable quality for med ica l data transfer is required . This parer disc usses simulation and implementation results of a low cost rclcmcdicinc system includ ing wireles s med ical interface and com munication infrastructu re.A simul ation hasbeen do ne to investiga te the netwo rkquality of service. The infrastructure has bee n also imp lemen ted using low cost 5.KGHztransceiver for backhauls and low cost 2.4GHz transce iverfor clien ts. Test resu ltshows that the lowcost rclemcdici nc system IS able to do rcet time communication between patie nt and medical staff with medicaldatarate up to2Mbps.Itsho wstha t thelowcos t tclemcdicinesystemusing wirele ss mesh netwo rk can be implementedin remot eareawithacceptab le medicaldata trans fer quality.

1. INTRODUCTION

Tclcmedicme is an emerging technology which cornbimng te leco mmunicatio n and information techno logy fo r medic a lpractice. It gives a new wa y to deliver health care services whe n the dista nce between do ctor and patient is significa ntly away. Tclemcdic ine can deliver hea lth care services to the patient even in remote area,

Pavlopoulosctal.(199K)haspresent edan exampleof telcrncdicmc advantage with implem entati o n on ambulatory patient care at remote area . Another application ha s beendoneby Sudhamonyeral.(200K) for cancer care in rural area. Iligh techno logy tclemedicme applicat ion in surgery has already been developed by Xiaohuierat.(2007).

Currently. the telcmed icine uses available wired and wirelessin fras tructure s.Tclemcdicineinfrast ructure s

with Wired netwo rk have been proposed by Al-Taer (200 5 )usmgIntegrated Servi ceDig italNetwork(ISDN). Asy nchrono us Trans ferModes(ATM) by Cabral& Kim

(1996). Vel)' Small Aperture Tcrrmnat (VSAT) by Pandian ct al. C~007) andAsymmetric Digital Subscriber Line (A DS L)byLingctal.(2005).Tclc mcd ie ine has also been impleme nt ed lt1 wireless network using Wire less

LAN (WLAN) proposed by Kugean er al. (2002). Worl dw ide lntcropcrabihty fo r Microwave Acces s tWIMAXj by Chorbcv cr

at.

(200R). Code Division Mu ltiple Access (CD/lil A) IX-EV DO by Yoo ct al (2005).GeneralPack etRadio Switch(GPRS) byGibso n cral. (2003) and 2G Groupe Special Mob ile (GSM )by Pavloponlos cr

at.

(199!!).

Each infrastructure has its OW I1 obstacle . 111

particularl y when they arc implement ed in a remotearea. Fo r exam ple. Asynch ro nou s Tran sfe r Mode (A TM) and Multi Pro to col Label Switch ing (MPLS) had some mobil ity and scalabili ty hrnitatrun, even both networks pro vide high Quality of Se rv ice(Qo S)and have stability ondeliv ering data [Na nda ct al., 2007). Thc frag.ilityof 3G Ut\1TS network tor telerncdtcinc has been explored by Y. E. Tan et <II. (2006), whe re the imple men tation costs arc high and do es nOI provide enough QoS Compa rison of ava ilable network in frusnuc nrrcs and tech nolog ies fo r rclcmcdicin esystem are summa rized in Table I. Itcan be shown that basedon cost. data rate and mob ility. the optimal solution fo rtetcmcdicincsystem is WirelessMeshNetwork(WM N).

Inorde rto inves tigate thequality and the possibil ity of U:-'JIlg WMN as a rclcme dicinc infra structure, a

simulation ofdata co mm unication in WMN using NS2 network simula tor has been done. Bes ides , the infrastructure and the medical data interface have been alsodevelopedandtested. This isrequiredto create alow costtclcmedicincsystem that has anacceptable qualityof service.

-bitrate investmentcost* operationalcost userdevice mobility

(Mbps) ~c:.:::o~st:--:--- -:-:-_ _

2.550,OOU H M VH No

155 VH H VH No

8 H M M No

0.J28 H M M No

4.09 VH M VH No

0.115 H L L Yes

0.256 H L L Yes

0.512 H M M Yes

3.6 VH M M Yes

54 L VL L Ycs

54 M VI. L Yes

Comparisonofavailablenetwork infrastrnctures/teclmologies fortelerncdicine system Table I

infrastructure!

tcchnology Fiber Optics

ATM ADSL

ISDN VSAT GPRS EDGE 3GUMTS

HSDPA WMN WiMAX Note:

"investment cost= cost of investment

number of user node thai can beservi ced VH=veryhigh.H=h igh.M=medi ull1. L=low.VL=-vcrylow

2. MEDICAL QUALITY OF DATA AND SERVICE

For this application. the muurnum data rate for accep table (good) quality and excellentqualityarclisted

in Table2.

Desiredoutputdatarate An application example of telemedicine system can

beseen in Fig.I.Itinvolved patientsanddoctorsthatare equipped with medicaldataassistant(MDA).Thc MDA acqu ires thc medicaldata using Medical Data lnrcrfacc (MDI).MDIretrievesmedicaldata fromvarious medical devices.Typicalmedical devicesarc electrocardiography machine (ECG). Doppler instrument, blood pressur e

monitor,ultrasound machine andstethoscope.The MDA areconnected through wireless router and tran sceiverfor data transmitting between patient and doctor. Two-way communication between patientand doctors is supported by came ra and micropho ne.All of patient medical data arecontinuouslyrecorded inside theserver for diagnosuc purposes.

Table 2 devices

ECG DopplcrInstrum ent BloodPressureMonitor

UltrasoundMachine Camera Stethoscope Micro hone

Total

ood

datarate excellent

J2kbps

160kbps Ikbps 400kbps 2.000kbps

160kbps 160kb s 2,893kb s

...

.

COfMmun tt(ll1 11I1r1ltrllC.lure

The nununum data rate for acceptable service in tclerncdicinc systemis323 kbps,whereasfor exce llence qualityminimumdatarate2.893kbps isrequired,

Up to now. there is no specific rule defining OoS provisions of telerncdicine application. In addition,

parameterizedOoSisaclearOoSboundwhicharcstated in termsofquantitative valuessuch as throughputs. end delay, jitter and packet loss. These OoS bounds arc explainedin Table3.

3. WIRELESS MESH NETWORK FOR

TELEMEDICINE SYSTEM

Hardware configuration for low cost telemedicinc communication infrastructure is shown in Fig. 2. This infrastructure is divided into three areas of implementation: client and indoor network, backhaul outdoornetworkand medical centralservice.

_ _--cPara meler throughput

delay jitter packe t loss

TableJ OoS for low costtclcmcdic ine system

dcflninon

packet arrival rate

thetunctakenbya packet toreach itsdestinatio n lime of arrivaldeviation between packets

perce ntage of non-rece iveddata oackcts

requncmeur

min323 kbps max 100rns

max50 ms

max5%

CLIENT&INDOOR OUTDOOR NETWORK CENTRALSERVICE

~.

rJ.,

~

-

.

_

.

~

( )

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V

~ w "V

(IA... ." .I

M'

._.

_IV

APPlICATION

.~.

Q]

IV

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·~

-~

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e

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_";::>

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OA'AD.\af

K~'

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,

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Fig. 2Hardwareconfiguration forlow cost tclcrncdic mccommu nicationinfras tructure

Table4 WMN outdoorbac khaulcharac teristic

IOm W 11 Mbps 2.470GHz inputpower (max)

data fate

chan nel frequency

Type omnidirection al

gain tran smitter 1dRi

ga inreceive r 1dBi rcceiv er sensilivi'l: -104 dRill

network inte rface antenna

Parameter value

NS2 versi o n2.33 networksimulato rhas been usedto simulate the Oo S pa rameterincl udingdela y, throughput.

jitte r and packet loss. Three protocols have bee n imple mented in the sim ulation. The simula tio n method and resu lts are reported bySupnyanto etal. (2001l). Fig.

3 shows thro ug hp ut as fu nctio n of hop number. Simulationre sult shows variatio nsof thro ughput foreach routing protocol. The biggcr hop number, the smaller through put. II isdue todelay and waiting lime inrouting mechan ism. DS [)V routing protoc o l inferred its throughput better than the other pro tocols . Simulat ion resultshows thatthe network able to tra nsfer the medical data up to 2Mb ps, eve n still more than 200 kbps for 6 hops. This re sul t show nthe ability of network to fu lfill theqoo d qualitymed icaldata transferrcqurremcr u.

Table 5 WMNindoorro utercharactensnc

va lue

10dBi

10 dBi -100dBm

20 km

I W

5.750 GHz. 54Mb p~ direction alantenna

antenna

Para meter

input powe r (max) channel frequen cy

datarate Type ga intra nsm itter

gainreceiver

rece iver sensitivi ty line ofsig htra nge

7 , -, -_ _ - ""-''''' _

networkinterface

In indoor netwo rk, a wireless router is connected to medical dev ices through MO l and connected to outdoor network viaswitc h.Outdoornetwo rkis mainstructureof wirel ess mesh netw or k. Th is co nfig uration enables a communicat ion between client and central service or

medical doc to r via Doctor -Medical Data Assistant (0 -MDA).Thisenable s alsomobilecom munica tion betwee n patient and medical doctor.

Chara cteristic of WMN outdoor backhaul arc desc ribed in Table4 The operational frequenc yof5.750 GHz ha s been used to overcome distance and obsta cles between backhaulco nnectio ns. Parameter s forthe W~lN indoor route r are described in Table 5. The operatio nal

frequ e ncy ofW M Nindoor router is 2.470 GHz.

-1 \

Fig.3Throughputcomparisonofeachrouting protocolin EPTsystem.

Table 6 MD1zcharacteristic

to the patient and MDlzb. Table 6 shows MOlz characteristics. MDlzb bas the same operational frequency as MOlz, but the modulation is slightly different. Table 7 showsMDlzb characteri lies.

Value

ornniantenna

IdBi IdBi

-92dBm

30m 100m Antenna

parametcr

Zi bee module type

gaintransmitter gainreceiver receiver sensitivity indoor coveragerange

lineofsightranee

•

~---.

I ,

4. WIRELESS MEDICAL INTERFACE

Value

2.411GHz 1.359 GHz 723300 bps 2.411UHz 1.359MHz 115200 bp

omniantenna

IdBi

IdBi -89dBm

100 m

- - - ,

. , I~, ~I ,[)I, IJ

t\' I\,hll. 1JIlJ nul ';'I){:

Fig.5 ivIDlzBlockDiagram Bluetoothmodule paramete r

nienna type

gaintransmitter gainreceiver average power line ofsiiluran c

channel frequency bandwidth

data rate

channel frequency bandwidth

datarate

11 'I \1,I>.t1

Table7 MDlzb characteristic

Fig.5 shows blockdiagram ofMOlz. Analog signal from medical sensor is conditioned, digitized and processed by a processor. The data from processor is converted to Zigbcc andthentransmittedout. The data is arranged in a frame as shown in Fig. 6. II consists of device 10, status, length of frame. data and checksum. TheZigbeemoduleis bidirectional. M017canreceivethe command through Zigbce module.

Bluel oot h Comm

I /

~

••j ZlgBeeComm

"In,

1

ll1'l tJ.lul.dECC o.lo'lr..

~

'''

-LtrllMrr;lrt"'oItNIMP 0YIl:_

~

.

.

In order to enable the connection belween common medical devices and network infrastructure. a wireless medical interface has been developed. The wireless medical interface is implemented using Zigbec and Bluctoothtechno logy.

Two kinds of wireless medical interface has been developed; MOlz and MDlzb. MOlz is a device which

acquires data from medical device and transmits it out through Zigbce network. while MDlzb coordinates the

Zigbcc networkas wellas communicates wi th Medical DataAssistantthroughBluetooth network.

Medical data is acquired by MDlz and then added with a frame as shown in Fig. 4. The data is then transmitted to MOlzb throughZigbee nerwork. MOlz IS able to send data up to 115200 bps. The bandw idth is

more than enough forvitalsign darn.The network has a PANID to differ withthe otherZigbeenetworks.

MDlzb coordinates thc Zigbcc network. It decides

which medicaldevice will communicate to in that time

and give themprioritybased011theirstatus,

Fig. 7 shows block diagramofMOlzb.IIconsistsof Zigbce module, two processors. D-Ialch, SRAI'vI, and Bluetoothmodu le.Data from MDlzis received byZigbcc module and processed by processor I. Delay may ignore

Fig.6Data FrameofMOlz

... ~ an

I.t..

I , " T "'1 It 1 1&.,,-lhl,r

III t",u

2 to adda frame as shown in Fig.8 beforetransmittedout by Bluetooth module. Bluetooth data is acquired by mobile data assistant. The Bluetooth module is bidirectional. MDlzb can receive the command through Bluetoothmodule.

3

(I c CI ;;.

di stance (m)

Fig.10MDlzbBluetoothsignal strength

Fig. II shows the signalstrength ofcommunication between P-MOA and WLAN router using WiFi communication.This result shows that the cover of 10 meters stillgive highSignalto NoiseRauo (SNR) from wirelessroutersensitivity.

1n.1 Ihlo

Fig.7MDlzb blockdiagram

• • ' ...,II~ , ~I' I 1I1,.r 1*'. '1....l.lUll

h~lf' Hl Itam

Fig.8Data frameofMDlzb

6

distance(01) 4

2

~

-s

~ ·10

0.- I-c ~ -:!O

'"

~ ~5

:;:.,.0

-3':>

band noise noise signal Location antenna

(MHz) high low strength (dBm) (dBm) (dBm) Location I

5

180

-9

-

1

06

-26

J 2

5

180

-

98

-1

07

-28

Location J

5180

-

98

-

1

08

-26

2 4

5180

-9

7

-

108

-28

Location 5

5180

-

98

-

106

-26

3

6

5180

-98

-

106

-26

Table8 Network performancetestingof each

backhaulatIkm

Fig.II WirelessrouterWiFisignal trengrh

Thetesting hasbeen done totransferthe medicaldata up to2Mbps.Test result shows the network isstillable tofulfill theminimum requirementstated inTableJ with

excellentsignalstrength.

The network performance test result is shown in Table8. The measuremen t isdonefor backhauls I km distance.The resultshow the noise rate varies fromirs

receiver sensitivity. The average signal for each backhaul in open space area with clear weather are in rangeof -26 and-28dBm.Thisgives theSNRvalues of 72dBforlow SNRand82dBfor highSNR.

11

8 6

Fig.9iVIOilsignalstrength I)

- II , 2 4

&j

.n

~

5. TESTING AND ANALYSIS

Thetesting has been done 10investigate the network performance and the rcliability of system including wirelessmedicalinterface.

Fig.9shows the testresult for MDlzsignalstrength. iVIDlz signalstrengthis the MDlz power to receive the databetween receiverat medicalinterfaceand transmitter at medical equipment communication using Zigbee communication. It should be higher rather than its receiver sensitivity (Signal Strength 2: R.'\ sensitivity) fromthespecificationof;'vIDlz,Testresultshowsthatfor the distance up to 10meters, the MOlz Signal strength gives theresult higher than itsreceiver sensitivityat -92 dBm.

,

The measurement has also been done for the data transmission between wireless medical interface and p, MDA client. Fig. 10 shows the signal strength of communication between medical interfaces through the P-tvlDAclientusing Bluetooth communicatio n.

-Tab le'l) COfU1CC'tlonchar acte ris ticperhopbetwee n

backhaul

REFERENCES

CO NCLUSION

Table 9 ~how~ the average vatucs from connecnce rma!>Urtmt'n1 In each number of hops. Hop is COUnlN: from the U~ In lOCAtion I 10 Illc desanauon in otber

locanon.The dalarare~ascalculatedfrom theaverage of data ,ale of cam user.Tt"!>tmgresultssbows thattilt' low COStltkma:hclI'le mfrastructure wu nm 3 bopcount with

dIStl.~ lT1OI'e than J km fulfIlls the requirement of

rncdlC31 datI. rafc of more tlun 2.8 Mbps for excellem

quallt) of mWicI.l data M!Xro \·c, . the ancnuatlOf1 of weather ':lnd ~lael~. weh n bUilding and trtt lui decreased IItt' SNRvalue ,"TO low than 72dBin disuf)CC' of U km.

A novel low cost telemcdicine system using WMN has been su~sfu llydeveloped andtes ted The svstcm consistsofwi~lC\smedi ca!interfaceandcommumca non in frastructure.

The ...rrclcss medical interface using Zigbec and

Bluetocthtechnctogy has been im ple me nted10enablethe

connection some mcdscal de vices to com munica tion infrastructure. The communicano n in fras truc tu re has been impleme nted usinglowCOM5.R GHz transceive rfor backhauls and to w(·0:.12.4 Gllz transceiver for clients.

Simulation and testresults sho w thatthe svstem isable10 transferlhe required medicaldataup10 2Mbps . .

In orde rTOenable the implement ation ofthis system. adataellcryptionand safely1Il0nnoring unitsofmed i ~al d",vices shou ldbeinlegral~d in Ih",syst"'m.

hop

,

)

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2.•

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in Bi c:di 31 InsI

nd Dr -In

I\luhammad lIaikal atria

rec iv d rh B.E. (200_) rom Unive.ita Indonesia and 1. c.

(2 from niversial DUI burg

E n, rern any. H I PhD

stud m in Faculty of Ele rI 31

Engm ring. UniversiI Tc:kn I

\a la, ia,

Indr a lIard ian ;\'lulyad i

rec iv d the B.E. (200·1) rom

lnsti tut T.knologiBandung.HeISa

Master student in Facultj of

Electri a\ Enginee ring. Univcr iti

T kn lou.Ma la ia.