Research Article QPRD: QoS-Aware Peering Routing Protocol for Delay-Sensitive Data in Hospital Body Area Network

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1 Moble Informaton Systems Volume 15, Artcle ID , 16 pages Research Artcle : QoS-Aware Peerng Routng Protocol for Delay-Senstve Data n Hosptal Body Area Network Zahoor A. Khan, 1 Shyamala Svakumar, 2 Wllam Phllps, 3 Bll Robertson, 3 and Nadeem Javad 4 1 CIS, Hgher Colleges of Technology, Fujarah Campus, P.O. Box 4114, Fujarah, UAE 2 Sant Mary s Unversty, Halfax, NS, Canada B3H 3C3 3 InternetworkngProgram,FE,DalhouseUnversty,Halfax,NS,CanadaB3H4R2 4 COMSATS Insttute of Informaton Technology, Islamabad 44, Pakstan Correspondence should be addressed to Zahoor A. Khan; zahoor.khan@dal.ca Receved 1 November 14; Accepted 15 January 15 Academc Edtor: Haroon Malk Copyrght 15 Zahoor A. Khan et al. Ths s an open access artcle dstrbuted under the Creatve Commons Attrbuton Lcense, whch permts unrestrcted use, dstrbuton, and reproducton n any medum, provded the orgnal work s properly cted. Consstent performance, energy effcency, and relable transfer of data are crtcal factors for real-tme montorng of a patent s data, especally n a hosptal envronment. In ths paper, a routng protocol s proposed by consderng the QoS requrements of the Body Area Network (BAN) data packets. A mechansm for handlng delay-senstve packets s provded by ths protocol. Moreover, lnear programmng based modelng along wth graphcal analyss s also done. Extensve smulatons usng the OMNeT++ based smulator Castala 3.2 llustrate that the proposed algorthm provdes better performance than other QoS-aware routng protocols n terms of hgher successful transmsson rates (throughputs), lower overall network traffc, no packets dropped due to MAC buffer overflow, and fewer numbers of packet tme outs n both the moble and statc patent scenaros. The scalablty of the protocol s demonstrated by smulatng a 24-bed real hosptal envronment wth 49 nodes. It s shown that, even n the larger real hosptal scenaro requrng the transmsson of delay-senstve data packets wth strngent delay requrements, outperforms comparable protocols. 1. Introducton A patent s real-tme health-related data montorng s possble wth the help of a new emergng feld, Body Area Networks (BANs). Body Area Network s a small wreless network whch conssts of sensors placed nsde or outsde of the human body. The body mplant or wearable sensors transmt the data to a central devce called Body Area Network Coordnator (BANC). BANC s computatonally more powerful devce then the body sensors. BANC s responsble for transferrng the sensors data to the next node or destnaton relably. Some mportant ssues of BAN data transmsson are to ensure the hgh relablty, low latency, compatblty wth movable sensors, and low energy consumpton. The specfc need of BAN communcaton s not fulflled by the exstng Personal Area Network (PAN) standards [1]. IEEE task group 6 was assgned a job n November 7 to suggest a BAN communcaton standard by the consderaton of short range transmsson, relablty and latency requrements of QoS, and less energy consumpton [2]. The real-tme montorng of patents requres the transmsson of delaysenstve data such as vdeo magng, moton sensng, and Electromyography (EMG) usng BAN. Some projects lke SMART [3], CareNet [4], AID-N [5], and ALARM-NET [6] provde dfferent methods to montor the patent data. In these methods, the transmsson of BAN data from body sensors to the central database s consdered and then BAN data s downloaded and montored from the central database. However, these technques do not montor or dsplay n real-tme BAN data n hosptal envronment. The advantages of usng a centralzed system are to have better control and mantan the data prvacy of the patent. However, traffc congeston, server falure, or lnk falure can cause consderable delays n montorng the patent data whch can badly affect treatment. On the other hand, dstrbuted

2 2 Moble Informaton Systems data approaches help to reduce the traffc load and can better accommodate patent moblty. The ZK-BAN peerng framework proposed n [7] suggests a semcentralzed system for relably montorng BAN data. The hybrd ZK-BAN uses bothcentralzedanddstrbutedtechnques. The routng protocols EPR, proposed and dscussed n [7], resolves the problem of handlng ordnary data packets. The QoS-aware peerng routng protocol for relabltysenstve data (QPRR) [8, 9] provdes a mechansm of handlng the relablty-senstve packets n addton to the ordnary data packets. The requrement of real-tme dsplay for delay-senstve packets s dfferent from those of ordnary and relablty-senstve packets. Hence, a new QoS-aware routng protocol s requred to handle delay-senstve packets. A novel routng protocol that addresses the ssue of handlng delaysenstve data and dsplayng n real-tme delay-senstve BAN data s proposed n ths paper. The proposed QoS-aware peerng routng protocol for delay-senstve packets () sdesgnedforthezk-banpeerngframeworkdscussedn [7]. provdes an nnovatve approach to the relable transmsson of ordnary packets (OPs) and delay-senstve packets (DSPs). The ntal results and archtecture of were presented n IEEE conference proceedngs [1]. Ths paper s organzed as follows: Secton 2 provdes the related work; Secton 3 dscusses the problem formulaton and modelng; Secton 4 provdes the proposed QoS-aware peerng routng protocol for delay-senstve data (); Secton 5 descrbes the performance evaluaton; Secton 6 dscusses the scalablty test of and Secton 7 presents the conclusons. 2. Related Work A smart montorng system of BAN data n hosptal envronment can resolve the challenges related to the management of patents medcal nformaton [11]. The Scalable Medcal Alert and Response Technology (SMART) [3] s desgned to montor the patent s data n hosptal emergency area. The datafromsensorsstransferredtothepdaandthenthepda sends t to the next ter by usng wreless standard 82.11b. CareNet [4] provdes an ntegrated wreless sensor based soluton to montor the patent s data from remote hosptals. The two-ter wreless communcaton s used n the projects [3, 4]. A GPS system s used n [5] to montor the patent s data only n outdoor BAN communcaton. A wreless sensor network for asssted-lvng and resdental montorng system wth a query based protocol s provded n ALARM-NET [6]. A three-ter communcaton approach s used n [12] to store the BAN data on the server and then make ths data avalable for the physcan to analyze the patent s data. The projects [3 6, 12] used a centralzed approach to montor the patent s data. However, the real-tme dsplay of data by consderng the delay requrements of delay-senstve packets s not consdered. To access the data from a centralzed server may cause delay and even a smple lnk falure can completely dsconnect the healthcare system from the central server. In [7], an energy-aware peerng routng protocol (EPR) was presented whch consders the energy level and geographc nformaton of the neghbor nodes for choosng the best next hop. The EPR only consders ordnary packets. It was shown that EPR has an overall lower energy consumpton than comparable protocols [11, 13 16] and provdes better results n terms of reduced overall network traffc, reduced number of packets forwarded by ntermedate nodes, and hgher successful data transmsson rates. However, EPR does not provde a mechansm for dealng wth delay-senstve packets (DSPs). In ths paper, delay-senstve packets are consdered by the proposed QoS-aware peerng routng protocol for delay-senstve data () and ther performance s nvestgated by comparng t to the exstng protocol [13]. In [13], categorzes the data packets nto four types: ordnary packets (OPs), crtcal packets (CPs), relablty-drven packets (RPs), and delay-drven packets (DPs). The [13] provdes better results for delaydrven packets than several prevously nvestgated methods [11, 14 16] n terms of end-to-end path delay. However, employs a hop-by-hop approach to determne the next hop. consders the neghbor devce wth the lowest delay, and the next hop then determnes the best next upstream hop wth least delay. The dsadvantage of ths hop-by-hop delay-drven approach employed n s that only neghborng nodes delay nformaton s consdered bysourcenode.thesourcenodeforwardsthepackettoa partcular neghbor node whch has lower node delay than therequreddelay.theneghbornodesendstheacknowledgement of the successfully receved packet to the source node. Now, the packet recevng neghbor node determnes ts best upstream node n terms of delay requrement and forwards the packet to the upstream node f the node delay of upstream node s less than the requred delay. In case the neghbor node does not fnd any upstream node wth node delay less than requred delay, then the packet s dropped. In ths case, the packet does not reach the destnaton, but the source node assumes that the packet has been successfully receved by the destnaton. Furthermore, the hop-by-hop approach used n causes an ncrease n overall network traffc, and the requred end-to-end latency may not be guaranteed. In ths paper, the proposed addresses these shortcomngs by selectng and choosng the next hop devce based on the lowest end-to-end path delay from the source node to the destnaton. 3. Problem Formulaton and Modelng The motvaton that BAN conssts of nodes connected wth each other va wreless lnks leads us to model t as a drected graph. Ths secton focuses on two ponts: () to maxmze throughput, and () to mnmze the end-to-end delay. These two problems are modeled va lnear programmng [17, 18] because requrements to these problems could easly be represented by lnear relatonshps Throughput Maxmzaton. We consder BAN as a drected graph G = (S, L), S = s, and L = l; S s the set of nodes and L s the set of drected graphs (lnks). If the network operatons are dvded nto rounds, each round r s the duraton from the network establshment tll the death

3 Moble Informaton Systems 3 ofallnodes;thenlnearprogrammngbasedmathematcal formulaton for throughput maxmzaton s as follows: where such that Max T (r), r R, (1) r T (r) = l (,Dst) T (,Dst) S, (2) l (,Dst) = { 1 f packet delvery s guaranteed { otherwse { (3) s selected to prevent routng latency for future demands, s addressed here. The lnear programmng problem s formulated as follows: where Mn DL path(,dst), S, (5) DL path(,dst) = { DL node() + DL path(j,dst) j = Dst { DL { node() j=dst, DL node() = DL trans() + DL queue+channel + DL proc, S (6) (7) B B max, (4a) such that E E, S, (4b) DL path(,dst) t out(,dst), S, (4c) f ( 1,) + d (,Dst) R tx, S, (4d) λ t f (,Dst), S. (4e) The objectve functon n (1) ams to maxmze throughput T durng each round r such that (2) assocates packet delvery from source to destnaton Dst wth lnk flag l.equaton(3) provdes detals about the status of l beng rased (l = 1) f packet delvery through that lnk s guaranteed else not (l = ). Constrant n (4a) provdes the upper bound for the allocated bandwdth B as B max. Smlarly, constrant n (4b) deals wth lmted energy constrant; that s, each node s equpped wth an energy source E such that E s upper bounded by E. Node ceases transmsson whenever ts battery s draned out, so, energy effcent utlzaton s very mportant (routng and MAC layer protocols play a crtcal role here). Constrant n (4c) comes nto consderaton f and only f (m/p) P QoS ; m path(s) out of total P satsfes the gven qualty of servce P QoS where DL path s the end-to-end delay and t out s the tmeout perod. Ths means that, as a frst prorty, QoS needs to be satsfed. Afterwards, f there s more than one QoS path, then as a second prorty end-to-end delay s checked. Transmsson range R tx constrant n (4d) demonstrates that packet delvery s successful f a source node transmts data to an n-range destnaton node where d (,Dst) s the dstance between source and destnaton. For data generaton rate λ, (4e) constrant entals flow conservaton such that the ncomng data flow f ( 1,) plus the data generated durng tme t should not exceed the outgong data flow f (,Dst). Volaton of (4c), (4d),and(4e) leads to packets beng dropped whch ultmately results n decreased throughput Delay Mnmzaton. The delay mnmzaton problem, whle routng dynamcally such that path for each request l path(,dst) = 1, S, (8a) R bt R max bt, (8b) t max t=1 λ arrval n n cap, (8c) < λ departure, S, (8d) node () s, S, (8e) N e bt Nproc bt. (8f) The objectve functon n (5) ams to mnmze the end-toend path delay DL path(,dst),where(6) depcts the two possble cases: communcaton va ntermedate node and wthout ntermedate node, and (7) defnes the node delay DL node() calculated at the network layer as the addton of packet delays due to transmsson DL trans(), queung DL queue, channel capturng DL channel,andprocessngdl proc. Constrant (8a) clearly says that the lnk through whch data s routed must be establshed where l path s the lnk flag. Constrant n (8b) provdes the upper bound of data rate R bt as R max bt such that R bt s nversely proportonal to DL trans accordng to (15) explaned n later Secton 4.4. Constrant n (8c) says that the number of transmtted packets n n 4 seconds (t max =4sec) should not exceed the packet handlng capacty n cap because, at neglgble load, there s constant small delay. However, queungdelaysoneachnodeareaddedassoonasthenetwork load ncreases and when n exceeds n cap delays ncrease wthoutbound.smlarly,constrantn (8d) deals wth queue stablty meanng that the packet arrval rate λ arrval should be always less than the packet departure rate λ departure.volaton of (8d) results n nonavalablty of buffer space leadng to queue nstablty whch n turn leads to congeston and thus causng ncreaseddelay. Constrantn (8e) states that the total number of nodes node() n the gven network s lmted such that has an nverse relaton wth DL channel.inother words, ncreasng the number of nodes means that there are more chances that one of the noncapturng nodes mght have

4 4 Moble Informaton Systems a lower backoff tme as compared to that of the capturng node, thereby ncreasng the dle tme due the backng off of noncapturng nodes. Constrant n (8f) deals wth DL proc.it s obvous that the total bt level errors N e bt should not exceed a certan threshold N proc bt ; otherwse ncreased erroneous bts wouldncreasedl proc and performance of the network would degrade n terms of processng delays at the nodes Graphcal Analyss. Consder the smplfed path B 3 -B 1 -NSC where B 3 candrectlysenddatatonscaswellas va B 1 (refer to Fgure 3 n Secton 4.4). Moreover, NSC can also send data to tself. For typcally assumed delay values, path delay s maxmum when B 1 s nvolved n forwardng the data of B 3 ntended for the destnaton NSC (.e., 5 ms), and path delay s mnmum when B 3 drectly communcates wth NSC (.e., ms). Let z = DL path(,dst), x = DL node(), and y = DL path(j,dst). The objectve functon n (5) can be reformulated as y (ms) L 1 :x+y=5 L 3 :y=3 P3(, 3) P4(, 3) L 4 :x= L L 5 :y= 2 :x= 1 P1(, ) P2(, ) x (ms) Fgure 1: Feasble regon. where Mn (z), (9) z=x+y (1) between B 3 and NSC. Smlarly, z=3 ms when B 1 drectly communcates wth NSC. On the other hand, end-to-end path delay s maxmum when B 3 communcates wth NSC va an ntermedate B 1 ; z=5 ms. such that x+y, x+y 5, x, y 3. (11a) (11b) (11c) The objectve functon n (9) ams to mnmze end-to-end delay regardng the selected path, whereas (1) llustrates nature of the objectve functon, that s, two-dmensonal lnear programmng problem. Constrants n (11a) and (11b) provde lower and upper bounds for the selected path, respectvely, whereas constrant n (11c) deals wth smlar bounds for x as well as y. For smplcty n calculaton, we replace the nequaltes n (11a), (11b), and(11c) wth equaltes, respectvely. In subject to the gven constrants, Fgure 1 shows the set of feasble solutons whch s obtaned by the ntersecton of lnes, L 1, L 2, L 3,andL 4,andsndcated by coloured regon such that each pont n the feasble regon satsfes each constrant. We can fnd the mnmum value of z by testng t at each of the vertces (refer to P1, P2, P3, and P4 nfgure1) as follows: at P1(, ): z=ms, at P2(, ): z= + = ms, at P3(, 3): z= + 3 = 3 ms, at P4(, 3): z= + 3 = 5 ms. The mnmum value of z s ms at x = and y =. However, ths value ndcates self transmsson or communcaton wthn NSC. The next mnmum value s z = ms showng the case of drect communcaton 4. QoS-Aware Peerng Routng Protocol for Delay-Senstve Data () Based on the mathematcal analyss n Secton 3, theproposed QoS-aware routng protocol used n an ndoor hosptal ZK-BAN peerng framework [7] s dscussed n ths secton. The proposed provdes a mechansm to (1) calculate the node delays and path delays of all possble paths from the source node to the destnaton,(2) determne the best path, and (3) choose the best next hop NH D based on the delay requrements of the packet. For each destnaton, the routng table contans nformaton about the next hop devce connected to the path wth the least end-to-end latency. For any DSP, f the path delay (DL path(,dst) )slessthanorequal tothedelayrequrement,thesourcenodesendsthedsp through that path. The archtecture of proposed, based on the mathematcal formulaton of the end-to-end path delay problem, s shown n Fgure 2. It conssts of seven modules: MAC recever, delay module (DM), packet classfer (PC), Hello protocol module (HPM), routng servces module (RSM), QoS-aware queung module (QQM), and MAC transmtter. The modules are dscussed below MAC Recever. The MAC recever receves the data or Hello packets from other nodes (BAN, MDC, or NSC). It checks the MAC address of the packet. It only forwards the broadcast packets or the packets whch have the same node s MAC address as destnaton address to the network layer Delay Module (DM). The delay module montors the tme requred to capture the channel (DL channel() ), MAC layer queung delay (DL MAC queue() ), and transmsson tme

5 Moble Informaton Systems 5 From upper layers Layer 3 Data packets QoS classfer Routng servces DSP Path selector OP Routng table constructor Energy-aware algorthm Delay algorthm Routng table Data packets Hello protocol Neghbor table Neghbor table constructor Delay calculaton Hello packet QoS-aware queung Packet classfer Hello packets OPDSP Hgher prorty Data or Hello packets MAC recever Delay module MAC transmtter Layer 2 Data or Hello packets Data or Hello packets From other nodes (.e. BAN, MDC, or NSC) Fgure 2: protocol archtecture. To other nodes (.e. BAN, MDC, or NSC) (DL trans() ) of a packet. The delay module sends ths nformaton to the network layer. The network layer uses ths nformaton to calculate the node delay (DL node() ) Packet Classfer (PC). The packet classfer (PC) receves all the packets from the MAC recever. The data packets and Hello packets are dfferentated by the PC. The PC forwards the data and Hello packets to the routng servces module and Hello protocol module, respectvely Hello Protocol Module (HPM). The neghbor table constructorandtheneghbortablearethetwosubmodulesof Hello protocol module. The nformaton receved from the delaymoduleofthemaclayerandthehellopacketssused bytheneghbortableconstructortoconstructtheneghbor table. Intally, Hello packets are broadcasted by each of type 1 (NSC) and type 2 (MDC) devces. The node receves the Hello packet. The neghbor table constructor of node calculates ts own DL path(,dst) based on the nformaton n the Hello packets. The Hello packet s updated and forwarded by node to the other nodes. The Hello packet felds of node j are shown as follows. Hello Packet Structure. Consder ID Dst L Dst ID j L j D (j,dst) E j T j DL path(j,dst) (12) The commonly used notatons n ths paper and ther descrptons are summarzed n notatons secton. The neghbor table contans felds for both hop-by-hop delay (DL node() ) and end-to-end path delay (DL path(,dst) ). The neghbor table constructor updates the neghbor table perodcally after recevng every new Hello packet. The neghbor table structure of node s shown as follows. The Neghbor Table Structure. Consder ID Dst L Dst ID j L j D (j,dst) D (,j) C j T j DL node() DL path(,dst) (13)

6 6 Moble Informaton Systems The node delay (DL node() ) can be found by addng the packet delays due to transmsson, queung, processng, and channel capturng: DL node() = DL trans() + DL queues+channel + DL proc. (14) The node updates ts Hello packets perodcally; 4 seconds are used n for smulaton purposes. The tme nterval 4 seconds s used because the delay module sends the delays of MAC queue and channel capture after every 4 seconds. The average transmsson delay (DL trans ) before sendng the Hello packets s calculated by usng DL trans = 1 n z=1 N bt(z), (15) R bt n where R bt s the data rate and as per BAN requrement 25kbpssusednthesmulatons.N bt s the total number of bts n each packet. n s the number of packets transmtted n 4 seconds. The delay due to the MAC and network layers queues andcapturngthechannelcanbecalculatedbyusngthe Exponentally Weghted Movng Average (EWMA) formula and s gven n DL queues+channel =(1 ρ) DL queues+channel +ρ (16) DL queues+channel, where queues are both network and MAC layers queues. Intal values of DL queues+channel are the delay of the frst packet sent by the node. ρ s the average weghtng factor that satsfes < ρ 1. The selecton of ρ value s heurstc and was chosen based on smulatons experence. The recommended values are.2 ρ.3. The best suted value of ρ found for smulatons s.2. The path delay between node and destnaton node Dst (DL path(,dst) )scalculatedbyusng DL path(,dst) = DL node() + DL path(j,dst), (17) where ntal value of DL path(j,dst) s zero when j=dst. An example of fndng the path delay from node (B 3 ) to Dst (NSC) s shown n Fgure 3. The delay calculaton of two paths B 3 -B 1 -MDC 2 -NSC (path 1) and B 3 -MDC 3 -B 2 -MDC 1 -NSC (path 2) s gven for llustratve purposes.thetypcalassumedvaluesarechosenforllustratedpurposes.thendvdualnodedelaysusednths example are gven below: DL node(nsc) = ms, (18a) DL node(mdc2 ) = 4 ms, DL node(b1 ) = 3 ms, DL node(b3 ) = ms, DL node(mdc1 ) = ms, DL node(b2 ) = 3 ms, DL node(mdc3 ) = 1 ms. (18b) (18c) (18d) (18e) (18f) (18g) The path delay of destnaton (DL path(dst,dst) )sapproxmately zero, because the tme requred to receve the packet from MAC to network layer s neglgble. So, n ths example ntal path delay s gven below: DL path(nsc,nsc) = ms. (19) Each node calculates the path delay from tself to the NSC. Frst, the calculatons of the path delay for path 1 (B 3 -B 1 -MDC 2 -NSC) are consdered. The path delay of MDC 2 (DL path(mdc2,nsc)) scalculated by usng (17): DL path(mdc2,nsc) = DL node(mdc2) + DL path(nsc,nsc). () Usng the values from (18a) and (19) n the above equaton, we get DL path(mdc2,nsc) = 4 + = 4 ms. (21) The path delay of BAN B 1 s calculated below: DL path(b1,nsc) = DL node(b1 ) + DL path(mdc2,nsc), (22) DL path(b1,nsc) = = 7 ms. The node B 3 determnes the path delay by usng the values from (18d) and (22): DL path(b3,nsc) = DL node(b3 ) + DL path(b1,nsc), (23) DL path(b3,nsc) = + 7 = 9 ms. In the same manner, the path delay of path 2 (B 3 -MDC 3 -B 2 -MDC 1 -NSC) can be calculated as follows: DL path(mdc1,nsc) = + = ms, DL path(b2,nsc) = 3 + = 5 ms, DL path(mdc3,nsc) = = 6 ms, DL path(b3,nsc) = + 6 = 8 ms. (24) Equatons (23) and (24) show that the path delays of path 1 and path 2 are 9 ms and 8 ms, respectvely. It s qute possble that the path wth less delay s longer (has more hops) than the other paths. As t s observed from the above example, path 2 ncludes fve devces and path 1 has four devces. However, the path delay of path 2 s lower than the path delay of path Routng Servces Module (RSM). The routng servces module s responsble for constructng the routng table, categorzng the data packets nto delay-senstve packets (DSPs) and ordnary packets (OPs). It also chooses the best path(s) for each category (DSPs or OPs) of traffc. QoS classfer, routng table constructor, path selector, and routng table are the submodules of routng servces module. The routng table structure for node s shown as follows. The Routng Table Structure for. Consder ID Dst L Dst NH E NH D DL path(,dst) (25)

7 Moble Informaton Systems 7 DL path(b3,nsc) = DL node(b3 ) + DL path(b1,nsc) =ms +7ms =9ms DL path(b3,nsc) = DL node(b3 ) + DL path(mdc3,nsc) =ms +6ms =8ms DL path(b3,nsc) = DL node(mdc3 ) + DL path(b2,nsc) =1ms +5ms =6ms B 3 DL path(b1,nsc) = DL node(b1 ) + DL path(mdc2,nsc) =3ms +4ms =7ms MDC 3 B 1 DL path(b2,nsc) = DL node(b2 ) + DL path(mdc1,nsc) =3ms +ms =5ms Path1 DL path(mdc2,nsc) = DL node(mdc2 ) + DL path(nsc,nsc) =4ms +ms =4ms B 2 Path2 DL path(mdc1,nsc) = DL node(mdc1 ) + DL path(nsc,nsc) =ms +ms =ms MDC 2 MDC 1 NSC DL path(nsc,nsc) = DL node(nsc) =ms Fgure 3: Example of fndng the path delay. The notatons and ther descrptons are lsted n notaton secton. Two next hop entres NH E and NH D are gven for each destnaton Dst n routng table. The routng table constructor contans the energy-aware and delay algorthms. The energy-aware algorthm dscussed n [7] s used to fnd next hop NH E for OPs. Resdual energy and geographc locaton of the neghbor nodes are consdered for choosng NH E. For DSPs, the new proposed algorthm fnds the best possble path to ensure the mnmum requred path delay. The routng table s constructed by usng the neghbor table entres. Neghbor table contans multple records for each destnaton. For example, Fgure3 shows that there are many paths from B 3 to NSC. Some of these paths are B 3 -B 1 -MDC 2 -NSC, B 3 -MDC 3 -B 2 -MDC 1 -NSC, and so forth. For each destnaton, the routng table constructor stores the next hop (NH D ) whch has the lowest latency. Algorthm 1 shows that node dentfes the next hop canddatesbysearchngtherecordswhchhavethesameid Dst ntheneghbortable.thepathdelayhasbeencalculatedby usng the neghbor table constructor and stored n neghbor table for each next hop canddate, usng (17).Thenodestores the neghbor nodes IDs n the varable NH (lne 2). If NH has onlyoneentry,thsmeanstheresonlyonepathavalable.the node stores ths entry to NH D (lne 4). Otherwse, the node sorts the NH entres n ascendng order of delay and then stores the frst entry whch has the lowest path delay n NH D (lnes 6-7). The next hop canddate NH D s then stored wth ts path delay value (DL path(,dst) )n the routng table. The data packets from both upper layers andpacketclassferarerecevedbyqosclassfer.theqos classfer classfes the packets nto DSP and OP data. For each data packet, the path selector (PS) checks the QoS requrement and chooses the most approprate next hop(s) by usng Algorthm 2. The path selector compares the delay requrement (DL req ) wth the path delay (DL path(,dst) )ofnh D whch s stored n the routng table. If the path delay (DL path(,dst) )slowerthan requred delay (DL req ), the packet s sent to NH D (lnes 3-4). Otherwse, the packet s dropped (lne 6). For ordnary packets, the PS returns the next hop NH E whch s dscussed by the EPR (lnes 8-9); else the packet s dropped QoS-Aware Queung Module (QQM). The routng servces module passes the data packets to the QoS-aware queung module (QQM) after choosng the approprate next hop(s). The QQM receves the data packets and separates these packets n two classes (DSP and OP). An ndvdual queue s used for each class of packets. QQM functons are thesameasdscussedn[13]. The prorty of the DSP queue s hgher than that of the OP queue. By default, the DSP queue wth hgher prorty sends the packets frst. The packets from lower prorty OP queue wll be sent only when the DSP queue s empty. However, for far treatment of OP data, a tmeout s used by all the queues. A queue sends the packets to the MAC layer wthn the perod specfed by the tmeout for that queue. QQM changes the control from hgher prorty queue to lower prorty queue after the queue tmeout occurs or when the hgher prorty queue s empty whchever s earler MAC Transmtter. The MAC transmtter receves the data and Hello packets from the network layer and stores t n

8 8 Moble Informaton Systems INPUT: Neghbor table, s neghbor table records NH (,Dst), Dst {MDC, NSC, BAN} (1) for each destnaton Dst {NSC, MDC, BAN} do (2) NH = {All neghbor nodesj NH (,Dst) } (3) f ( NH ==1) then (4) NH D NH (5) else f ( NH >1) then (6) Sort NH n ascendng order of DL path(,dst) (7) NH D =frstneghbornodej NH; (8) end f (9) end for Algorthm 1: Routng table constructon algorthm for delay-senstve packets. INPUT: Routng table, s routng table records NH (,Dst), Dst {MDC, NSC, BAN} (1) for each data packet do (2) f data packet s delay-senstve packet (DSP) (3) f (DL path(,dst) DL req ) then (4) send to NH D (5) else (6) Drop the packet mmedately (7) end f (8) else f data packet s Ordnary Packet (OP) (9) send to NH E (1) else (11) drop the packet mmedately (12) end f (13) end for Algorthm 2: Path selector algorthm for delay-senstve packets. the queue. The queue works n a Frst-In-Frst-Out (FIFO) fashon. It transmts the packets after capturng the channel by usng CSMA/CA algorthm. MDC 1 B 1 (2, 5) (5, 5) 5. Performance Evaluaton Smulatons are performed on OMNeT++ based smulator Castala 3.2 [19]. In ths secton, the proposed algorthm s compared wth the [13] and noroutng protocols. In noroutng, the delay-senstve data packets are forwarded to random next hop devces nstead of algorthm s next hop based on end-to-end path delay routes. The network parameters used n smulatons are shown n Table 1. Three scenaros are consdered for smulaton. All the nodes used n scenaro 1 are statc, whereas the source node B 4 s movng n scenaro 2. Scenaro 3 s used for the scalablty test of the protocol. The transmt power used n the smulatons s 25 dbm. The performance of the s measured by calculatng the throughput, number of packets forwarded by the ntermedate nodes, overall network traffc, packets tmeout due to not fulfllng the requred delay condton,andpacketsdroppedduetothebufferoverflow. The better results provded by are n accordance wth the equatons used n Secton 4.Thehgherthroughputsdue totheuseofobjectvefunctonn,asdescrbedn(1), and the least volatons of (4c), (4d), and(4e). The smulaton NSC and MDC 4 MDC 3 B 3 B (, 3) 4 (3, 3) (6, 3) (9, 3) MDC2 (2, 1) B 2 (5, 1) Fgure 4: Node deployment for scenaro 1. results show that the end-to-end path delay mechansm, as dscussed n Sectons 3.2 and 4.4, usednhelpsto reduce the packets forwarded by ntermedate nodes and the packetsdroppedduetothebufferoverflow,whchresults n hgher throughput and lower overall network traffc. To acheve a 97% confdence nterval for the llustratve results, the average of three runs s smulated n every experment whch may ntroduce a maxmum error of 3 1 3,basedon the error calculaton done by Castala 3.2 smulator []. The results obtaned for frst two scenaros are dscussed below Scenaro 1: Statc Nodes. Fgure 4 shows the deployment of the expermental network for scenaro 1. All the nodes are

9 Moble Informaton Systems Successful transmsson rate (%) Forwarded packets (k packets) noroutng noroutng (a) Throughput (b) Packets forwarded by ntermedate nodes 7 12 Traffc load (k packets) Number of packets tme outs (k) noroutng noroutng (c) Overall network traffc (d) Packets tmeout 8 3 Buffer overflow (k packets) Energy consumpton (J) noroutng noroutng (e) Packets dropped due to MAC buffer overflow (f) Overall energy consumpton Fgure 5: Performance comparson for dfferent parameters when source nodes are statc.

10 1 Moble Informaton Systems Deployment Task Area Deployment type Number of nodes Intal nodes locatons Intal node energy Buffer sze Lnk layer trans. rate Transmt power Applcaton type Max. packet sze Traffc type Table 1: Parameters nformaton. Scenaros 1 and 2: 9 m by 9 m Scenaro 3: 21 m 16 m Scenaro 1: all nodes are statc Scenaro 2: movable source node B 4 Scenaro 3: hosptal envronment Scenaros 1 and 2: 8 nodes (4 BANs, 3 MDCs, 1 NSC) Scenaro 3: 49 nodes (24 BANs, 24 MDCs, 1 NSC) Scenaros 1 and 2: NSC(,3), MDC 1 (2,5), MDC 2 (2,1), MDC 3 (3,3) B 1 (5,5), B 2 (5,1), B 3 (6,3), B 4 (9,3) Scenaro 3: shown n Fgure J (= 2 AA batteres) 32 packets 25 Kbps 25 dbm Event-drven 32 bytes CBR (Constant Bt Rate) MAC IEEE Default values Smulaton Tme 3 seconds (3 seconds are setup tme. Smulaton results are the average of three rotatons.) statc n ths scenaro. The type 1 devces (BANCs: B 1,B 2,B 3, and B 4 ) are consdered as source nodes, and type 2 devces (NSC and MDCs) are the destnaton nodes. B 1 sends packets to MDC 1,B 2 sends packets to MDC 2,B 3 sends packets to MDC 3,andB 4 sends packets to NSC. The data of B 4 has to go through the other devces to reach NSC. The source nodes send a total of k delay-senstve packets. The throughput, packets forwarded by ntermedate nodes, overall network traffc, number of packets tmeout, packets dropped due to MAC buffer overflow, and overall energy consumpton are calculated after every 1 packets untl 4 k and then every 4 packets sent by all BANCs. From Fgure 5(a), tsseenthatconsstentlyprovdes throughput of 94% or more. In comparson, noroutng provdes an average of 74% transmsson rate, whereas has a throughput rangng from 49% to 57%. For low offered data loads of 1 k, has a throughput of 57% that contnues to decrease especally for hgh offered data loads of k, when the throughput s 49%. The low throughput n may be explaned by the way t selects the next hop usng the energy-aware geographc forwardng scheme. Because the best next hop does not guarantee that t has the smallest latency connecton to the destnaton, the packet may tmeout when t s sent usng the best next hop. Moreover, the energy-aware geographc forwardng scheme used n prefers the nearest next hop canddate n terms of hop count and gnores next hop nodes havng a lower delay. As a result, the network traffc s ncreased and the packets are dropped due to tmeout before reachng the destnaton. resolves these ssues by usng the end-toend path delay. B 2 s the closest node to the destnaton nodes (.e., NSC or MDCs) as shown n Fgure 4. In[13], B 2 s responsble for forwardng the data packets from other nodes to NSC or MDCs. Ths results n more energy consumpton for B 2 and ncreased traffc congeston experenced by B 2. EPR resolves these problems by choosng the most approprate next hop. In the proposed scheme, the BAN coordnator does not send data to another BAN coordnator unless t s absolutely necessary. Fgure 5(b) shows the number of packets forwarded by the ntermedate nodes. It s seen from Fgure 5(b) that number of data packets forwarded by ntermedate nodes before reachng the destnatons n areonaverage.5tmesand3tmeslowerthanand noroutng, respectvely. The lower number of forwarded packets by ntermedate nodes helps to reduce the overall network traffc. Fgure 5(c) shows the total network traffc generated by,, and noroutng as a functon of the offered traffc load. From ths Fgure, t s seen that generates about an average of 26%and99%lesstraffcnthenetworkcomparedto and noroutng, respectvely. The path calculaton n consders the delay of all the nodes and uses the best path delay nformaton to select the next hop to send the data from source to destnaton. In contrast to the method used n whch decdes on the mmedate next hop based merely on next hop delay nstead of overall path delay, each upstream hop n sends the packet to ts next hop and resultant path n may not be the most optmal. From Fgure 5(d) t s observed that and noroutnghavenopacketsthatweretmedoutforalloffered

11 Moble Informaton Systems 11 NSC and MDC 4 (, 3) MDC 1 B 1 (2, 5) (5, 5) MDC 3 (3, 3) MDC 2 B 2 (2, 1) (5, 1) Fgure 6: Node deployment for scenaro 2. B 3 B 4 (6, 3) (9, 3) traffc loads (number of data packets sent by source node range from k to k). has better performance n terms of reduced overall network traffc and fewer numbers of dropped packets due to tmeout, because the clear endto-end path delay nformaton helps the packet to reach the destnaton wthn the requested delay requrement. Moreover, the path calculaton n consders the delay of all the nodes n the network and chooses only those paths whch can guarantee delverng the packet to the destnaton before t tmes out. Fgure 5(e) shows that there s no packet dropped due to themacbufferoverflownprotocol.thssduetono volaton of the model constrants as explaned n Sectons 4.1 and 4.2. The source node chooses the path whch provdes the maxmum throughput and mnmum end-to-end path delay as descrbed n [16, 18]. Only few packets are dropped n, whereas 7.5 k packets are dropped n noroutng. It s seen from Fgure 5(f) that the end-to-end path delay mechansm used n does not affect the overall energy consumpton when compared wth. and consume the same 18 Joules to 275 Joules of energy when 1 k to k packets are sent by source nodes. On the other hand, the energy consumpton of noroutng protocol s 2.6 Joules to 47.7 Joules when 1 k to k packets are sent by source nodes. The data packets n noroutng are randomly forwarded to three neghbor nodes wthout consderng the delay requrements. The addtonal computatons for delay n consume on average 6 tmes more energy than noroutng. However, t must be noted that noroutng results n on average a 99% hgher overall network traffc. Ths may be attrbuted to the 3 tmes more packets forwarded by ntermedate nodes n noroutng resultng n a % lower throughput as compared to. In summary, outperforms and noroutng whenthesourcenodesstatc Scenaro 2: Moble Source Node. Inthesecondscenaro, thesourcenodeb 4 s movng at the speed of 1 meter per second vertcally as shown n Fgure 6. It s assumed that the speed of a fast walkng patent s 1 meter per second. Once agan, t s observed that provdes better results than and noroutng n case of moble source node scenaro. Fgure 7(a) shows that the throughput s n excess of 8% n for offered data packet rates less than 8 k. The throughput reduces slghtly at hgher offered data packet rates of 8 k and more and reduces to 71% when total offered packets sent by the source are k. In contrast wth, t s observed that when the offered data packet load s ncreased, suffers from a much lower successful data transmsson rate that reduces from 5% to 32% wth resultant low throughput. Due to node moblty, the source node moves away from ts neghbor nodes resultng n a connecton loss whch results n more packets beng lost. handles ths stuaton much more gracefully than. In, the moble nodes resume the connecton more rapdly once the nodes come back nto the range of neghbor node. The overall lower throughput n ths scenaro sduetothepacketlostwhenthemoblenodesoutofrange. Equaton (4d) n Secton 3.1 also supports ths behavor. Accordng to (4d), the packet delvery s successful only f a source node transmts data to an n-range destnaton node. The packets are dropped when the movable nodes go out of range. The noroutng provdes the lower throughput wth an average of 64%. Fgure 7(b) shows that the number of packets forwarded by the ntermedate nodes n s on average.75 tmes and 9 tmes lower when compared to the number of packets forwarded by ntermedate nodes n and noroutng protocols, respectvely. The routng mechansm used n the protocol helps to send the data drectly to the destnaton wthout transferrng the packets to the ntermedate nodes n case the destnaton s n range. It can be seen n Secton 3.3 that use of ntermedate node results n larger delay and n Secton 3.2 that the backoff of other noncapturng nodes also contrbutes to exacerbatng the problem. The performance of noroutng for ths parameter sworstastforwardsupto26kpacketswhchncreasesthe overall network traffc. It s observed from Fgure 7(c) that the overall network traffc n s about 25% and 5% less than and noroutng protocols, respectvely, for all offered network data loads consdered. Ths s due to the end-to-end path calculaton mechansm used n. The delay of all the nodes s consdered and algorthm selects the best next hop, on the bass of end-to-end path delay nformaton, to send the data from source to destnaton. From Fgure 7(d),tsseenthathasnopacketsthat were tmed out for data packet transmssons at 8 k or less. The selecton of mnmum end-to-end path delay, gven n [18], helps to send the data through a path where lower packets tme out occurs. For hgh data packets (above 8 k), the source node moves out of the neghbors rado range whch causes more packets to tme out. On the other hand, has more tmed out packets than. Intally for low offered data packet rates below 4 k, about 4% of data packets were tmed out, and for hgher offered data packets (above 4k)the4%ofdatapackettmeoutsncreaseto5%(approxmately). Ths s because the packets travel through dfferent nodes by usng hop-by-hop delay calculaton as dscussed n detal n scenaro 1. Equaton(9) n Secton 4.2 shows that the delay on each node s the summaton of four dfferent delays (.e., transmsson (DL trans ), MAC and network queues

12 12 Moble Informaton Systems 1 3 Successful transmsson rate (%) Forwarded packets (k packets) noroutng noroutng (a) Throughput (b) Packets forwarded by ntermedate nodes Traffc load (k packets) Number of packets tme outs (k) noroutng noroutng (c) Overall network traffc (d) Packets tmeout 1 3 Buffer overflow (k packets) Energy consumpton (J) noroutng noroutng (e) Packets dropped due to MAC buffer overflow (f) Overall energy consumpton Fgure 7: Performance comparson for dfferent parameters when source node s moble.

13 Moble Informaton Systems 13 3 m BAN 19 (5, 15) MDC 19 (4, 14) BAN (8, 15) MDC (7, 14) BAN 21 (11, 15) MDC 21 (1, 14) BAN 22 (14, 15) MDC 22 (13, 14) BAN 23 (17, 15) MDC 23 (16, 14) BAN 24 (, 15) MDC 24 (19, 14) 3 m 3 m 2 m BAN 18 (3, 12) MDC 18 (4, 11) 2 m 2 m MDC 13 MDC 14 MDC 15 MDC 16 MDC 17 (7, 11) BAN (1, 11) BAN (13, 11) BAN 15 (16, 11) BAN 16 (19, 11) BAN 17 (8, 1) (11, 1) (14, 1) (17, 1) (, 1) 3 m 16 m 3 m NSC (4, 7) MDC 8 BAN 8 MDC 9 (7, 8) (8, 7) (1, 8) BAN 9 (11, 7) MDC 1 (13, 8) BAN 1 (14, 7) MDC 11 (16, 8) BAN 11 (17, 7) MDC 12 (19, 8) BAN 12 (, 7) 3 m 2 m 2 m MDC 1 MDC 2 MDC 3 MDC 4 MDC 5 MDC 6 MDC 7 BAN 1 (3, 3) (4, 3) BAN 2 (7, 3) BAN 3 (1, 3) BAN 4 (13, 3) BAN 5 (16, 3) BAN 6 (19, 3) BAN 7 (2, ) (5, ) (8, ) (11, ) (14, ) (17, ) (, ) 3 m 21 m 3 m Fgure 8: Scenaro 3. Node deployment for 24 patent beds n hosptal envronment. (DL queue ), channel (DL channel ), and processng (DL proc ). The calculatonsdonebyoneachnodencreasethe processng delay whch causes the ncrease of overall node delay. The hgher node delay results n packet tme out. The source node moblty makes the packet tme out worse than scenaro 1 of Fgure 5(d). Fgure 7(e) shows that there are no packet drops due to MAC buffer overflow n and protocols, whereas 9 k packets are dropped n noroutng. The performance of s smlar to n terms of MAC buffer overflow; however, has on average 39% lower throughput and an average of 25% hgher overall network traffc. From Fgure 7(f), t s observed that the overall energy consumptons of and are 18.9 Joules to Joules when 1 k to k packets are sent by source nodes. The noroutng consumes 2.6 Joules to 47 Joules when 1 k to k packets are sent by source nodes. The computatons for delay n are almost smlar to the but provdes on average 25% lower overall network traffc, 73% fewer packets forwarded by ntermedate nodes, and, more mportantly, a 4% hgher successful data transmsson rate (throughput) as compared to. In summary, the overall performance of s better than and noroutng when the source node s moble. 6. Scalablty Test: Real Hosptal Envronment wth 24 Beds (49 Nodes) A real 24-patent-bed hosptal s consdered for the scalablty test of routng protocol, as shown n Fgure 8. The approxmate area covered s 16 m by 21 m whch s smlar to the Hematology-Oncology Unt of the Chldren Hosptal named IWK Health Centre Halfax, Canada. The dstance between two beds s 3 meters whch s n accordance wth the recommended transmsson range for BAN communcaton n hosptal envronment. The total nodes used n the deployment area are 49 (24 BANs, 24 MDCs, and 1 NSC). Each BAN transmts the data to ts peer MDC. All the BANs and MDCs are sendng or recevng Hello protocols to/from other nodes and the NSC. Both MDCs and BANs are movable. Generally, BANs can move freely anywhere and the movement of a MDC s only wthn the room where t s placed. It s assumed that the MDC of one room has a connecton wth the MDC of the next room.

14 14 Moble Informaton Systems 1 18 Successful transmsson rate (%) Network traffc (k packets) 57.5 Packets sent by source nodes (k) noroutng Packets sent by source nodes (k) noroutng (a) Throughput versus offered load (b) Overall network traffc 25 3 Buffer overflow (packets (k)) Packets tme out (k) Packets sent by source nodes (k) noroutng Packets sent by source nodes (k) noroutng (c) Packets dropped due to MAC buffer overflow (d) Packets tmeout Fgure 9: Performance comparson for dfferent parameters of scenaro 3. The smulaton results show that performs better than and noroutng even when the number of nodes s ncreased to 49. From Fgure 9(a) t s seen that the throughput provded by s n excess of 91%, whereas the throughput of noroutng and protocols s on average 74% and 52%, respectvely. From Fgure 9(b), t s observed that the overall network traffc of s 5% and 25% less than noroutng and protocols, respectvely. Fgure 9(c) shows that the packet drops due to MAC buffer overflownandprotocolsareneglgble, whereas 9k packets are dropped n noroutng. Fgure 9(d) shows that there are no packets tmeouts due to not fulfllng the delay requrements n and noroutng. On the otherhand25kpacketsaretmedoutn.fromthese results t s shown that s equally effectve when the deployment area s larger, and number of nodes has been ncreased to smulate a real hosptal scenaro wth 24 patent beds. 7. Concluson ThepapermodelsthewrelessBANasadrectedgraphand derves condtons for throughput maxmzaton and endto-end delay mnmzaton. It s shown that effcent energy utlzaton s crtcal to the proper desgn of the routng and MAC layer protocols. Smlarly, delay s mnmzed by formulatng the BAN end-to-end path delay as a lnear programmng problem wth multple constrants to be satsfed smultaneously. Basedonthemathematcalanalyss,anovelmodular QoS-aware routng protocol for hosptal BAN communcaton s proposed n ths paper. The archtecture of the new protocol conssts of seven modules: the MAC recever, the delay module (DM), the packet classfer (PC), the Hello protocol module (HPM), the routng servces module (RSM), the QoS-aware queung module (QQM), and the MAC transmtter. The proposed routng protocol provdes

15 Moble Informaton Systems 15 a mechansm for the end-to-end path delay calculaton of all possble paths from a source to destnaton and then decdes the best possble path by consderng the path delay requrements of the delay-senstve packets. OMNeT++ based smulator Castala 3.2 s used to test the performance of the proposed protocol () and compare t wth and noroutng. The smulatons are performed for both the movable source and statonary scenaros. A scalablty test s done wth larger deployment area and by usng hgher number of nodes. The results show that the offers over 94% successful data transmsson rates for delay-senstve packets n a statonary patent scenaro. provdes about 35% better results n terms of successful transmsson rate than n the movable patent scenaro. The smulaton results show that the mproves the relablty of Body Area Networks by 4% on average for each scenaro by decreasng the number of packet tme outs wth zero and averagng 729 packets for the statc and moble patent scenaros, respectvely. In addton, results n an average of 25% lower overall network traffc for each moble and statc patent scenaros as compared to smlar protocols. The scalablty test results prove that outperforms and noroutng even when a hgher number of nodes are employed n the BAN. provdes on average 93% throughput wthout any packet beng tmed out and any packet beng dropped due to MAC buffer overflow. Notatons for the Proposed Algorthm Node : Sourcenode Node j: Neghbornodeofsourcenode Node Dst: Destnaton node (.e., NSC, MDC, BAN) ID Dst : Destnaton ID L Dst : Destnaton locaton ID j : Neghbornodej ID L j : Neghbornodej locaton D (j,dst) : Dstance between neghbor node j and destnaton Dst E j : Resdualenergyofnodej T j : Devcetypeofnodej D (,j) : Dstance between node to neghbor node j NH (,Dst) : Next hop between node and destnaton Dst NH E : Energy-aware next hop NH D : Next hop for delay-senstve packets DL path(,dst) :Pathdelayfromnodetodestnaton Dst DL node() : Tme delay wthn the node DL req : Requred path delay for delay-senstve packets. Conflct of Interests The authors declare that there s no conflct of nterests regardng the publcaton of ths paper. References [1] B.Zhen,M.Patel,S.Lee,E.T.Won,andA.Astrn, tg6-techncal-requrements, IEEE Project: IEEE P82.15 Workng Group for Wreless Personal Area Networks (WPANs), 11, tg6-closng-report-march-11.ppt. 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16 16 Moble Informaton Systems sensor networks, Internatonal Journal of Sensor Networks, vol. 4,no.1-2,pp ,8. [16] M. Razzaque, M. Alam, M. Rashd, and C. Hong, Multconstraned QoS geographc routng for heterogeneous traffc n sensor networks, n Proceedngs of the 5th IEEE Consumer Communcatons and Networkng Conference (CCNC 8), Kyung HeeUnversty,LasVegas,Nev,USA,January8. [17] J. Elas and A. Mehaoua, Energy-aware topology desgn for wreless body area networks, n Proceedngs of the IEEE Internatonal Conference on Communcatons (ICC 12), pp , Ottawa, Canada, June 12. [18] N. Ababneh, N. Tmmons, J. Morrson, and D. Tracey, Energybalanced rate assgnment and routng protocol for body area networks, n Proceedngs of the 26th IEEE Internatonal Conference on Advanced Informaton Networkng and Applcatons Workshops (WAINA 12), pp , Fukuoka, Japan, March 12. [19] NICTA, Castala, Natonal ICT Australa, 11, [] A. Bouls, Castala, wreless sensor network smulator, NICTA, 11, Castala+-+User+Manual.pdf.

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