BANDWIDTH OPTIMIZATION OF INDIVIDUAL HOP FOR ROBUST DATA STREAMING ON EMERGENCY MEDICAL APPLICATION

Transcription

1 ARPN Journal of Engneerng and Appled Scences Asan Research Publshng Network (ARPN). All rghts reserved. BANDWIDTH OPTIMIZATION OF INDIVIDUA HOP FOR ROBUST DATA STREAMING ON EMERGENCY MEDICA APPICATION A. K. M. Fazlul Haque 1, Md. Hanf Al 1 and M Adnan Kber 2 1 Department of Computer Scence and Engneerng, Jahangrnagar Unversty, Dhaka, Bangladesh 2 Department of Appled Physcs, Electroncs and Communcaton Engneerng, Unversty of Dhaka, Dhaka, Bangladesh E-Mal: akm_haque@yahoo.com ABSTRACT Ths paper presents a new bandwdth estmaton method for ndvdual hop for hgh-speed, non-nvasve, and faster convergence transmsson n multple medcal data networks. Avalable Bandwdth Estmaton Technque for ndvdual Hops (ABETH) has been developed employng parameters lke Hop (H), Capacty (C), Bandwdth (B), Avalable Bandwdth (AB) etc. Bandwdth estmaton technques, tools and methods are consdered to develop the technque and t represents an effectve combnaton of dfferent other exstng technques amng to explot the postve aspects of them. More precsely, the technque whch s mpled n the method modfes and ntegrates the one recent tool SPRUCE whch estmates avalable bandwdth and the IP layer capacty estmaton formula whch measures capacty. Ths technque provdes a lnear combnaton of capacty versus bandwdth whch satsfes the lnk utlzaton demand. Keywords: avalable bandwdth, hops, capacty, utlzaton factor, dsperson. 1. INTRODUCTION The term bandwdth frequently dstngushes the amount of data that the network preserves transfer per unt of tme. Bandwdth estmaton s of concentraton to users wshng to optmze the performance of ndvdual hop. Technques for accurate bandwdth estmaton are also mportant for traffc engneerng and capacty plannng support. Currently avalable bandwdth estmaton tools utlze a dversty of strateges to measure these metrcs. Bandwdth also relates to the spectral wdth of electromagnetc sgnals or to the propagaton characterstcs of communcaton systems. In the context of data networks, the term bandwdth quantfes the data rate that a network lnk or a network path can transfer. The concept of bandwdth s central to dgtal communcatons, and specfcally to packet networks, as t relates to the amount of data that a lnk or network path can delver per unt of tme [1-4]. For medcal applcatons, such as patents vdeo streamng, mage processng, the bandwdth avalable to the applcaton drectly mpacts applcaton performance. It s needed to develop the method to optmze the usage of the bandwdth for ndvdual hop. In data networks, generally users can only approxmate the bandwdth of lnks or paths from end -toend measurements, wthout any nformaton from network routers [1]. To transfer hgh data rate nformaton and perfect synchronzaton, every node needs to know the bandwdth of the ndvdual hop. There s some works on bandwdth estmaton for dfferent applcatons. Exstng bandwdth estmaton tools measure one or more of three related Metrcs lke capacty, avalable bandwdth, and bulk transfer capacty (BTC). All exstng technques lke varable packet sze (VPS) probng, packet par/tran dsperson (PPTD), self-loadng perodc streams (SoPS), trans of packet pars (TOPP) and tools PATHOAD, SPRUCH measure end to end avalable bandwdth are descrbed n detals. Mehmet et al. mplemented the bandwdth estmaton technque n a vdeo streamng smulaton envronment that also ncluded a delayconstraned rate adaptaton algorthm at the sender [5]. u Mn et al. redefned the avalable bandwdth based on probablty and statstcs and evaluated ther method n controlled and reproducble envronment usng NS2, and the smulatons showed the method was accurate, effcent, quck and non-ntrusve [6]. P. Koutsaks proposed a new dynamc satellte bandwdth allocaton technque whch was based on accurate vdeoconference traffc predcton, and the work was shown to provde very good throughput and delay results [7]. Alm et al. modfed two bandwdth effcent AB estmaton mechansms-probegap and Resource Frendly Bandwdth Estmaton (RFBE), and evaluated ther performance over a crypto- parttoned red-black network [8]. Haohuan et al. paper proposed an effcent method for Wreless Bandwdth Detecton (WBD) usng packet probng approach on moble nodes [9]. Polychrons proposed and evaluated the work for the effcent ntegraton of hgh qualty vdeo traffc wth web data packet traffc over a burst-error wreless channel of very hgh capacty [10]. Estmaton of avalable bandwdth for ndvdual hop s a challengng task. It s extremely essental to employ bandwdth effcently. If we know the ndvdual hop s bandwdth then we can send suffcent data for ndvdual hop and we do not face synchronous problem. For ths reason, we can use bandwdth effcently whch s helpful to bandwdth optmzaton. If we know ndvdual hop bandwdth then we can desgn a network effcently and ths desgn can mantan requred avalable bandwdth at the endpont. Ths paper focuses on the optmzaton of bandwdth measurement technques performed by the lnk hosts of a path wthout requrng admnstratve access to transtonal routers along the path and provdes a lnear combnaton of capacty versus bandwdth whch satsfes the lnk utlzaton demand. 63

2 ARPN Journal of Engneerng and Appled Scences Asan Research Publshng Network (ARPN). All rghts reserved. 2. BACKGROUND AND THEORY The general workng prncple of bandwdth estmaton wth the metrcs, especally capacty, avalable bandwdth has been ntroduced. The ncorporaton of Bandwdth optmzaton of ndvdual hop for robust data streamng and the exstng theoretcal background of related felds has also been consdered. Internet, for example, most data packets need to go through several routers before they reach ther fnal destnaton. Each tme the packet s forwarded to the next router, a hop occurs. The more hops, the longer t takes for data to go from source to destnaton. A layer 2 lnk, or segment, can normally transfer data at a constant bt rate, whch s the transmsson rate of the segment. For nstance, ths rate s 10 Mb/s on a 10BaseT Ethernet segment, and Mb/s on a T1 segment. The transmsson rate of a segment s lmted by both the physcal bandwdth of the underlyng propagaton medum as well as ts electronc or optcal transmtter/recever hardware. At the IP layer a hop delvers a lower rate than ts nomnal transmsson rate due to the overhead of layer 2 encapsulaton and framng. Specfcally, suppose the nomnal capacty of a segment s c 2. The transmsson tme for an IP packet of sze 3 bytes s (1) Where H s the total layer 2 overhead (n bytes) needed to encapsulate the IP packet. So the capacty c 3 of that segment at the IP layer s (2) Where C s the capacty of the th hop, and H s the number of hops n the path. The hop wth the mnmum capacty s the narrow lnk on the path [1]. In a lnk of capacty C and for a packet of sze, the transmsson delay s Bt = / C. A packet par experment conssts of two packets sent back-to-back,.e., wth a spacng that s as short as possble, from the source to the snk. Wthout any cross traffc n the path, the packet par wll reach the recever dspersed by the transmsson delay n the narrow lnk. So, the recever can calculate the capacty C of the path from the measured dsperson, as C = /. Another mportant metrc s the avalable bandwdth of a lnk or end-to-end path. The avalable bandwdth of a lnk relates to the unused or spare capacty of the lnk durng a certan tme perod. So even though the capacty of a lnk depends on the underlyng transmsson technology and propagaton medum, the avalable bandwdth of a lnk addtonally depends on the traffc load at that lnk, and s typcally a tme-varyng metrc. At any specfc nstant n tme, a lnk s ether transmttng a packet at full lnk capacty or dles, so the nstantaneous utlzaton of a lnk can only be ether 0 or 1. Thus, any meanngful defnton of avalable bandwdth requres tme averagng of the nstantaneous utlzaton over the tme nterval of nterest. The average utlzaton for a tme perod t) s gven by (4) Where u(x) s the nstantaneous avalable bandwdth of the lnk at tme x and the averagng effect llustrated n Fgure-1. Note that the IP layer capacty depends on the sze of the IP packet relatve to the layer 2 overhead. For 10BaseT Ethernet, c 2 s 10 Mb/s and H 2 s 38 bytes (18 bytes for the Ethernet header, 8 bytes for the frame preamble, and the equvalent of 12 bytes for the nterframe gap). So the capacty the hop can delver to the IP layer s 7.24 Mb/s for 100 byte packets, and 9.75 Mb/s for byte packets. From the above equaton, the maxmum transfer rate at the IP layer results from MTU-szed packets. Extendng the prevous defnton to a network path, the capacty c of an end-to-end path s the maxmum IP layer rate the path can transfer from source to snk. In other words, the capacty of a path establshes an upper bound on the IP layer throughput a user can expect to get from that path. The mnmum lnk capacty n the path determnes the end-to-end capacty C that s, (3) Fgure-1. Instantaneous utlzaton for a lnk. In ths example the lnk s used durng eght out of 20 tme ntervals between 0 and T, yeldng an average utlzaton of 40 percent. et us now defne the avalable bandwdth of a hop over a certan tme nterval. If C s the capacty of hop and u s the average utlzaton of that hop n the gven tme nterval, the average avalable bandwdth A of hop s gven by the unutlzed fracton of capacty, A = (1 u ) C. Extendng the prevous defnton to an H-hop path, the avalable bandwdth of the end-to-end path s the mnmum avalable bandwdth of all H hops, 64

3 ARPN Journal of Engneerng and Appled Scences Asan Research Publshng Network (ARPN). All rghts reserved.. (5) The hop wth the mnmum avalable bandwdth s called the tght lnk1 of the end-to-end path. Fgure-2. A ppe model wth flud traffc. Fgure-2 shows a ppe model wth flud traffc representaton of a network path, where each lnk s represented by a ppe. The wdth of each ppe corresponds to the relatve capacty of the correspondng lnk. The shaded area of each ppe shows the utlzed part of that lnk s capacty, whle the unshaded area shows the spare capacty. The mnmum lnk capacty C 1 n ths example determnes the end-to-end capacty, whle the mnmum avalable bandwdth A 3 determnes the end-to-end avalable bandwdth. As shown n Fgure-2, the narrow lnk of a path may not be the same as the tght lnk. Several methodologes for measurng avalable bandwdth make the assumpton that the lnk utlzaton remans constant when averaged over tme (.e., they assume a statonary traffc load on the network path). Whle ths assumpton s reasonable over relatvely short tme ntervals, durnal load varatons wll mpact measurements made over longer tme ntervals [1]. Snce the average avalable bandwdth can change over tme, t s mportant to measure t quckly. Ths s especally true for applcatons that use avalable bandwdth measurements to adapt ther transmsson rates. In contrast, the capacty of a path typcally remans constant for long tme ntervals. Therefore the capacty of a path does not need to be measured as quckly as the avalable bandwdth [1]. 3. RESUTS AND DISCUSSIONS After the analyss of prevously cted technques, a necessty of a technque to measure avalable bandwdth of ndvdual hops has been approached. The method proposes Avalable Bandwdth Estmaton Technque for ndvdual Hops that represent an effectve combnaton of dfferent technques amng to explot the postve aspects of them. More precsely, the technque of ths method modfes and ntegrates the one recent tool SPRUCE for avalable bandwdth estmaton and the IP layer capacty estmaton formula for measurng capacty for ndvdual hop. From the capacty estmaton formula, we get the capacty whch s delvered by the hop to the IP layer s 9.75 Mb/s for 1500-byte packets. Here Capacty, C = 9.75 Mb/s and Packet Sze, = 1500 byte = 1500*8 bts = 12000bts. We know from the formula that C = /. So = /C = 12000/ (9.75*10 6 ) = ms. For Avalable Bandwdth Estmaton Technque for ndvdual Hops (ABETH), we have to ntroduce C s the capacty of the th hop and A s the avalable bandwdth of the th hop. Here = 1, 2, 3 H. H s the number of hops n the path. For avalable bandwdth measurement there s a delay occurs n hop. We consder delay d occurs n the th hop then the capacty formula can be modfed as C = ( ). If delay s ncreased lnearly then delay dfference between hop to hop s same. And f 0.001ms s delay ncreased lnearly per hop and varable Packet Sze, = 1500 byte = 1500*8 bts = bts. From the defnton we get the avalable bandwdth of a hop over a certan tme nterval. If C s the capacty of hop and u s the average utlzaton of that hop n the gven tme nterval, the average avalable bandwdth A of hop s gven by the unutlzed fracton of capacty, A = (1 u) C. At any specfc nstant n tme, a lnk s ether transmttng a packet at full lnk capacty or dles, so the nstantaneous utlzaton of a lnk can only be ether 0 or 1. So for utlzaton 1 avalable bandwdth s zero and we get the followng table (Table-1) and fgure (Fgure-3). Table-1. AB estmaton parameters for dfferent capactes usng utlzaton 1. C = A = C (ms) ( )

4 ARPN Journal of Engneerng and Appled Scences Asan Research Publshng Network (ARPN). All rghts reserved. Avalable Bandwdth Capacty Fgure-3. AB estmaton graph for dfferent capactes usng utlzaton 1. If we use ABETH technque to measure C, for utlzaton 0 technque then we get the followng table (Table-2) and fgure (Fgure-4). Table-2. AB estmaton parameters for dfferent capactes usng utlzaton 0. C = A = C (ms) ( ) Avalable Bandwdth Capacty Fgure-4. AB estmaton graph for dfferent capactes usng utlzaton 0. From SPRUCE, f gn s the spacng of back-toback probe packets on the tght lnk and gout the spacng measured at the recever, the AB s calculated as: A = [1- {(g out g n ) / g n }] C. Wth SPRUCE, the tght lnk and narrow lnk are assumed to be the same. But utlzaton 100% or 0% do not occur n a lnk. Agan SPRUCE tool can be used for tght lnk and applcable for end to end. So here we consderng all aspects ntroduce a new parameter called lnk used factor l u, whch can be used for all lnk. l u = R / (T + l ). Where l u = lnk used factor for th hop. R = packet or bt receved at the end of th hop. T = packet or bt transmtted at the startng of th hop. l = loss n the th hop. Here = 1, 2, 3 H. H s the number of hops n the path. The avalable bandwdth of a hop can be measured by the followng new formula A = (1 lu ) C. Or, A = (1 (R / (T + l ))) (/ ( )). If T = 4 unt, R = 3 unt and l = 0.5 unt then lu = Table-3 and Fgure-5 shows the results of the fnal attaned parameters. Most of the works related to ths feld consder the parameter of lnk utlzaton whch s subtracted from the total lnk utlzaton reclne n always 1. In AB defnton, utlzaton s consdered as 1 or 0; t means lnk wll be used 100% or 0% whch s practcally mpossble. In SPRUCE, t consders back to back packet space for tght lnk and back packet space measurng n the Table-3. AB estmaton parameters wth ABETH usng dfferent capactes. C = A = (1 (ms) ( ) lu ) C

5 ARPN Journal of Engneerng and Appled Scences Asan Research Publshng Network (ARPN). All rghts reserved. Avaable Bandwdth Capacty Fgure-5. AB estmaton graph wth ABETH usng dfferent capactes. recever. But we use a parameter called lnk used factor whch s practcally applcable for all cases. We use transmttng packets or bts n startng of the hop, recevng packets or bts at the end of the hop and loss occur n the hop for each lnk. Ths s practcally acceptable for lnk utlzaton porton. Suppose for transmttng 100 bts, 80 bts have been transmtted at the startng of ths lnk and 70 bts have been receved at the end of the lnk. 10 bts have been lost n the case. So lnk utlzaton porton wll be between 70-80%. Now we verfy our lnk used factor l u, whch can be used for all lnk. l u = R / (T + l ). l u = 70/(80+10) = 0.77 = 77%. Ths s smlar to the lnk used fracton as expected. Proper ncluson and detal understandng n the above that the proposed avalable bandwdth estmaton for ndvdual hop behaves lnearty n all cases n terms of the varable of utlzaton factor where as the exstng method for ndvdual hop gve the output n terms of the value of utlzaton factor ether s 0 or CONCUSIONS In ths paper, a new bandwdth estmaton method for ndvdual hop whch sgnfes an effectve combnaton of dfferent other technques has been optmzed. Parameters lke Hop (H), Capacty (C), Bandwdth (B), Avalable Bandwdth (AB) etc. have been used to ntegrate the technque. Dfferent exstng schemes have been employed to attan stable detecton results, so that the method can acheve a hgh accurate hop bandwdth estmaton result. The graphcal representatons of the technque and the comparatve analyss wth other technques have also been stated. Synchronzaton problem of the exstng system have been elmnated by the technque executed by the lnk hosts of a path and provded a lnear combnaton of capacty versus bandwdth exsted whch satsfed the lnk utlzaton demand n a lnk REFERENCES [1] R. S. Prasad M. Murray C. Dovrols K. Claffy J.G. and Tompkns Bandwdth estmaton: metrcs, measurement technques and tools Network. IEEE. Volume 17, Issue 6, Nov.-Dec. pp [2] Botta A, Pescape A., Ventre G On the performance of bandwdth estmaton tools. Systems Communcatons, Proceedngs August. pp [3] Sommers J. Barford P, Wllnger W A Proposed Framework for Calbraton of Avalable Bandwdth Estmaton Tools. Computers and Communcatons, ISCC '06. Proceedngs. 11th IEEE Symposum on June. pp [4] Tafour M. Nat-Abdesselam, F. Smplot-Ryl D RC-MAC: Reduced Collson MAC for Bandwdth Optmzaton n Wreless ocal Area Networks. Computer Systems and Applcatons, AICCSA '07. IEEE/ACS Internatonal Conference on May. pp [5] Mehmet U. Demrcn Bandwdth estmaton and robust vdeo streamng over e wreless lans. Multmeda and Expo, ICME IEEE Internatonal Conference on 6-6 July. pp [6] u Mn, Sh Jngln, Zhongcheng Kan, Zhgang Ma Jan A New End-to-End Measurement Method for Estmatng Avalable Bandwdth. Proceedngs of the 8 th IEEE Intl. Symposum on Computers and Communcaton (ISCC 03). [7] P. Koutsaks A new effcent scheme for the allocaton of satellte bandwdth based on vdeoconference traffc estmaton. IEEE. [8] Alm Mohammad, Orle Brewer, Arun Ayyagar Bandwdth Estmaton for Network Qualty of Servce Management. Mltary Communcatons Conference MICOM IEEE, October. pp [9] Haohuan Fu, dong n and Weja Ja Effcent wreless lnk bandwdth detecton for IEEE networks communcatons. ICC IEEE Intl Conference, May. Vol. 5, pp [10] Polychrons Koutsaks Effcent wreless bandwdth allocaton for MPEG-4 vdeos ntegrated wth web traffc networkng. Intl conference on systems and Intl conference on moble communcatons and learnng technologes, Aprl. p