Improved FEC: Improving The Efficiency of Forward Error Correction Coding In Reducing The Network Packet Loss

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1 Improved FEC: Improvig The Efficiecy of Forward Error Correctio Codig I Reducig The Network Packet Loss Kaakam Siva Ram Prasad 1, M.V.S.S Nagedraadh 2, M.Satya Sriivas 3 M.Tech Studet, Computer Sciece ad Egieerig, Sasi Istitute Of Techology ad Egieerig, Tadepalligudem, Adhra Pradesh, Idia 1 Head Of Departmet, Departmet Of CSE, Sasi Istitute Of Techology ad Egieerig, Tadepalligudem, Adhra Pradesh, Idia 2 Asst. Prof.,, Departmet Of CSE, Sasi Istitute Of Techology ad Egieerig, Tadepalligudem, Adhra Pradesh, Idia 3 Abstract I this paper we explores a method for measurig the performace of FEC codig combiig with iterleavig i reducig the packet loss i IP etworks. I order to evaluate the performace of FEC data ca be trasfer from the source to destiatio ad creates the packet loss volutarily, at the destiatio the lost packets ca recovered usig FEC decoder. The performace of the FEC codig ca be measured usig a aalytical method stated i this paper. Here we use the sigle multiplexer etwork model for trasmissio of the data from multiple sources to destiatios. I this a uified approach provides a itegrated framework for explorig the compromises betwee the various key parameters i.e. chael codig rates, iterleavig depths, block legths. It provides the selectio of various optimal codig strategies with various QOS requiremets ad system costraits. Idex Terms- FEC Codig, iterleavig, packet loss rates, multiplexer etwork model, multi sessio ad sigle sessio. 1. INTRODUCTION The packet trasport service provided by represetative packet-switched etworks, icludig IP etworks, is ot reliable ad the quality-of-service (QoS) caot be guarateed. The Packets may be lost o their route, Switchig odes requires more processig power as the packet switchig protocols are more complex, Switchig odes for packet switchig require large amout of RAM to hadle large quatities of packets, A sigificat data trasmissio delay occurs - Use of store ad forward method causes a sigificat data trasmissio. Fig1: Packet switched etworks (datagram) Packets may be discarded due to excessive bit errors ad failure to pass the cyclic redudacy check (CRC) at the lik layer, or be discarded by etwork cotrol mechaisms as a respose to cogestio somewhere i the etwork. Forward error correctio (FEC) codig has ofte bee proposed for ed-to-ed recovery from such packet losses. FEC ca be defied as A class of methods for cotrollig errors i a oe-way commuicatio system. FEC seds extraiformatio alog with the data, which ca be used by the re Copyright to IJARCCE

2 ceiver to check ad correct the data. Codes that iclude the umodified iput i the output are systematic, while those that do ot are osystematic. A ovel techique based o forward error correctio (FEC) has bee proposed that allows the destiatio to recostruct missig data packets by usig redudat parity packets that the source adds to each block of data packets. Example: a aalog to digital coverter that samples three bits of sigal stregth data for every bit of trasmitted data. If the three samples are mostly all zero, the trasmitted bit was probably a zero, ad if three samples are mostly all oe, the trasmitted bit was probably a oe. The simplest example of error correctio is for the receiver to assume the correct output is give by the most frequetly occurrig value i each group of three. Triplet received _00 0 0_0 0 00_ _0_ _11 1 1_1 1 11_ _1_ Iterpreted as This allows a error i ay oe of the three samples to be corrected by "democratic votig". This is a highly iefficiet FEC. I practice FEC codes typically examie the last several doze, or eve the last several hudred, previously received bits to determie how to decode the curret small hadful of bits Such triple modular redudacy, the simplest form of forward error correctio, is widely used. FEC works by addig check bits to the outgoig data stream. Addig more check bits reduces the amout of available badwidth, but also eables the receiver to correct for more errors.the mai advatage of the FEC is reduces the retrasmissio of the lost packet. Forward Error Correctio is particularly well suited for satellite trasmissios, where badwidth is reasoable but latecy is sigificat. The use of FEC i applicatios provides a double-edged sword. From a ed user s perspective, FEC ca help recover the lost packets i a timely fashio through the use of redudat packets, ad geerally addig more redudacy ca be expected to improve performace provided this added redudacy does ot adversely affect the etwork packet loss characteristics. O the other had, from the etwork s perspective, the widespread use of FEC schemes by ed odes will icrease the raw packet-loss rate i a etwork because of the additioal loads resultig from trasmissio of redudat packets. Therefore, i order to optimize the ed-to-ed performace, the appropriate trade-off, i terms of the amout of redudacy added, ad its effect o etwork packet-loss processes, eeds to be ivestigated uder specific ad realistic modellig assumptios. Types of FEC: The two mai categories of FEC are block codig ad covolutioal codig.1) Covolutioal codes work o bit or symbol streams of arbitrary legth. This code ca be tured ito a block code, if desired. Covolutioal codes are most ofte decoded with the Viterbi algorithm, though other algorithms are sometimes used. 2) Block codes work o fixed-size blocks (packets) of bits or symbols of predetermied size. There are may types of block codes, but the most otable is Reed-Solomo codig because of its widespread use o the Compact disc, the DVD, ad i computer hard drives. Block ad covolutioal codes are frequetly combied i cocateated codig schemes i which the covolutioal code does most of the work ad the block code (usually Reed-Solomo "mops up" ay errors made by the covolutioal decoder. Advatages: EDAC has a umber of advatages for the desig of high reliability digital systems: 1) Forward Error Correctio (FEC) eables a system to achieve a high degree of data reliability, eve with the presece of oise i the commuicatios chael. Data Copyright to IJARCCE

3 itegrity is a importat issue i most digital commuicatios systems ad i all mass storage systems. 2) I systems where improvemet usig ay other meas (such as icreased trasmit power or compoets that geerate less oise) is very costly or impractical, FEC ca offer sigificat error cotrol ad performace gais. 3) I systems with satisfactory data itegrity, desigers may be able to implemet FEC to reduce the costs of the system without affectig the existig performace. This is accomplished by degradig the performace of the most costly or sesitive elemet i the system, ad the regaiig the lost performace with the applicatio of FEC. I geeral, for digital commuicatio ad storage systems where data itegrity is a desig criterio, FEC eeds to be a importat elemet i the trade-off study for the system desig. The itroductio of the Per FEC lie of FEC ecoders ad decoders makes powerful FEC implemetatio a realistic goal for most digital commuicatio ad storage systems. More tha ever before, FEC is available for a wide rage of applicatios. Most telecommuicatio systems used a fixed chael code desiged to tolerate the expected worst-case bit error rate, ad the fail to work at all if the bit error rate is ever worse. However, some systems adapt to the give chael error coditios: hybrid automatic repeat-request uses a fixed FEQ method as log as the FEQ ca hadle the error rate, the switches to ARQ whe the error rate gets too high; adaptive modulatio ad codig uses a variety of FEQ rates, addig more error-correctio bits per packet whe there are higher error rates i the chael, or takig them out whe they are ot eeded. Averagig oise: To reduce the errors FEC could be said to work by "averagig oise"; sice each data bit affects may trasmitted symbols, the corruptio of some symbols by oise usually allows the origial user data to be extracted from the other, ucorrupted received symbols that also deped o the same user data. Because of this "risk-poolig" effect, digital commuicatio systems that use FEC ted to work perfectly above a certai miimum sigal-to-oise ratio ad ot at all below it. This all-or-othig tedecy becomes more proouced as stroger codes are used that more closely approach the theoretical limit imposed by the Shao limit. Iterleavig FEC coded data ca reduce the all or othig properties of trasmitted FEC codes. However, this method has limits. It is best used o arrowbad data. This explores a framework for usig Forward Error Correctio (FEC) codes with applicatios i public ad private IP etworks to provide protectio agaist packet loss. The framework supports applyig FEC to arbitrary packet flows over ureliable trasport ad is primarily iteded for real-time, or streamig, media. This framework ca be used to defie Cotet Delivery Protocols that provide FEC for streamig media delivery or other packet flows. Cotet Delivery Protocols defied usig this framework ca support ay FEC scheme (ad associated FEC codes) that is compliat with various requiremets defied i this documet. Thus, Cotet Delivery Protocols ca be defied that are ot specific to a particular FEC scheme, ad FEC schemes ca be defied those are ot specific to a particular Cotet Delivery Protocol. Iterleavig: Iterleavig i computer sciece is a way to arrage data i a o-cotiguous way i order to icrease performace. It is used i: Time-divisio multiplexig (TDM) i telecommuicatios, Computer memory ad Disk storage. Iterleavig is maily used i data commuicatio, multimedia file formats, radio trasmissio (for example i satellites) or by ADSL. The term multiplexig is sometimes used to refer to the iterleavig of digital sigal data. Iterleavig was used i orderig block storage o diskbased storage devices such as the floppy disk ad the hard disk. The primary purpose of iterleavig was to adjust the timig differeces betwee whe the computer was ready to trasfer data, ad whe that data was actually arrivig at the drive head to be read. Iterleavig was very commo prior to the 1990s, but faded from use as processig speeds icreased. Moder disk storage is ot iterleaved. A method for makig data retrieval more efficiet by rearragig or reumberig the sectors o a hard disk or by splittig a computer's mai memory ito sectios so that the sectors or sectios ca be read i alteratig cycles. i.e. Iiterleavig was used to arrage the sectors i the most efficiet maer possible, so that after readig a sector, time would be permitted for processig, ad the the ext sector i sequece is ready to be read just as the computer is ready to do so. Matchig the sector iterleave to the processig Copyright to IJARCCE

4 speed therefore accelerates the data trasfer, but a icorrect iterleave ca make the system perform markedly slower. Here we explores a brief study of the overall effectiveess of packet-level FEC codig, employig iterlaced Reed- Solomo codes, i combatig etwork packet losses ad provide a iformatio- theoretic methodology for determiig the optimum compromise betwee ed-to-ed performace ad the associated icrease i raw packet-loss rates usig a realistic model-based aalytic approach. Ituitively, for a give choice of block legth we expect that there is a optimum choice of redudacy, or chael codig rate, sice a rate too high (low redudacy) is simply ot powerful eough to effectively recover packet losses while a rate too low (high redudacy) results i excessive raw packet losses due to the icreased overhead which overwhelms the packet recovery capabilities of the FEC code 1. Sigle Source Model Sigle multiplexer model- The performace of the etwork is limited by a sigle bottleeck ode, the etwork ca ofte be modelled i terms of the sigle multiplexer. The sigle multiplexer is queuig system which cosist of three parts oe is the arrival process of the packets from N differet sources S i at arrival rate i, secod buffer that to hold up to the k packets ad last oe is a output lik with averagig packet service rate, assume that packet service times are idepedet ad idetically Distributed (i.i.d) with a expoetial distributio ad average packet service time T=1/, the ormalized load to system is /. The packet arrives to the sigle multiplexer from sigle source or multiple sources. The sigle source correspods to the per-flow cotrol from the traffic (assigs fixed badwidth). Whereas multiple source havig o per-flow cotrol is applied. Here the packet shares the badwidth of the output ad buffer. Fig. 2 sigle multiplexer etwork model Source Model- Assume that the packet arrival process for each source S i is reewal process. The packet iterval times are i.i.d with probability desity fuctio a(t). erlag iter arrival time distributio is ( t) a( t) ( h 1)!, t 0 Copyright to IJARCCE h1 e t For erlag distributio, the average arrival rate is i / h whe h=1, a(t) becomes expoetial ad arrival h process is Poisso whe, the variace of a(t) coverges to 0 ad the iterval time becomes determiistic with period 1 / i System model for FEC performace Evaluatio Cosider commuicatio system illustrated i Fig.1 suppose there are N homogeeous ad idepedet data sources sharig the sigle multiplexer ad each source geerates packets with average rate i. The FEC coder for each source applies the Reed Solomo codes. RS(, k) to the packets from the source, which meas for every block of k source iformatio packets it creates additioal -k parity packets to the etwork. The chael codig rates is give by R C = k/. because of this chael rate, the packet arrival rate ito the etwork will icrease i i c. / R The radom variable N p deotes the umber of lost packets withi a block. If Np k, the assume that all the lost packets are recovered by the chael decoder. Assume that p ( deotes the block error distributio, the expected umber of lost packets withi a block is E Np jk 1 j * P( Ad the expected umber of the lost iformatio packets withi a block is E NI ENp *( k / j * P( *( k / jk 1

5 Fially the effect iformatio packet loss rate after chael decodig is PLR eff = E[N I]/k = j * P( / j k1 Fig3. Commuicatio Chael Evaluatio Metric: Packet loss probability or Frame loss probability The frame loss metric is more suitable tha the packet loss probability for evaluatio of FEC performace the frame lost probability FLR eff is give by FLR = P( jk 1 eff ) The differeces betwee residual packet loss probabilities ad frame-loss probabilities with decodig ad without decodig deoted by FLR eff FLR wo respectively. A sigle-multiplexer model for this bottleeck ode is widely used to aalyze the associated queuig-related Packet losses, e.g., losses due to buffer overflows ad excessive delays. Sice the correlatio level of the packetloss process has great impact o the FEC efficacy, this depedece usig the autocorrelatio fuctio of the packetloss process Autocorrelatio fuctio of packet loss processes- For this packet loss process we use the autocorrelatio fuctio to characterize the depedece betwee the packet loss evets over the time, let {Y i } radom sequece represet the packet loss process with 1 deotig the loss ad 0 deotig the receptio if {Y i } is statioary the autocorrelatio fuctio of {Y i } is give as E[( Yi y( l) E[ 1 y)( Yi ( Yi y) y)] Where l is the lag ad y is the expectatio of the sequece {Y i }. The performace of FEC i recoverig etwork packet losses. Redudat parity packets was proposed to recostruct lost data packets ad the correspodig performace evaluatio idicated that residual packet-loss rates ca be reduced up to three orders of magitude. FEC performace with sigle source FEC without Iterleavig - Suppose there is oly oe user for multiplexer the key quatity i evaluatig the residual packet loss rate after FEC decodig is p (, the blockerror distributio for a arbitrary umber of cosecutive packets. Queuig system there are two types of queuig system deoted as M/M/1/K queue: fiite buffer queue with Poisso itervals ad expoetial service times ad extesio of G/M/1/K queue: the fiite buffer with geeral idepedet ad idetically distributed iterval times ad expoetial service times. Fig. 4 state trasitio of arrival-epoch system size Aalysis of Block error Distributio: suppose there is oly oe source sharig multiplexer ad the packet iter arrival times are i.i.d with arbitrary probability desity fuctio a (t), sigle multiplexer ca be modeled as a stadard G/M/1/K queue. Discrete-time marcov chai: let X be the o.of packets i the buffer just before the th packet arrives at the system because the memoryless property of the expoetial service time { X} lets cosider the above figure 4 with state space S={0,1,2, K}. Numerical example: The Fig. 4 shows the effective packet loss rates PLR eff computed accordig to PLR eff = E[N I]/k = j * P( / j k1 With differet codig block size =63,127,255 ad 511 as a fuctio of codig rates R C = k/. havig the Poisso arrivals (h=1), =0.8, k=10. 2 ] Copyright to IJARCCE

6 Compared to Fig. 5 shows that for more determiistic source arrivals a icreased codig rate Rc is required to achieve the optimum performace. Figure demostrate that with iterleavig the performace of FEC codig ca be greatly improved, ad iterleavig with eve larger depth ca achieve icreasigly improved performace. Fig5: effective packet loss rates With differet codig block size =63,127,255 ad 511 as a fuctio of codig rates R C = k/. havig the Poisso arrivals (h=1), =0.8, k=10 The above fig shows the FEC performace with differet umbers of sources multiplexed, where the load from each source is fixed at λi = 0.02 with buffer size K = 10 ad codig block size =63. It shows that, with a icrease i the umber of sources N, the effective packet-loss rates icrease due to the icreased system load. Suppose ow the load from each source is agai λi = 0.02 ad the required effective packet-loss rate is FEC with Block Iterleavig- FEC performace is ofte limited by the bursty ature of typical packet-loss processes, ad block iterleavig techiques are frequetly used to reduce the burstiess of the packet-loss processes i etworks, thereby improvig FEC performace. I this sectio, we aalyse the efficacy of iterleavig i reducig the burstiess of etwork packet-loss processes ad i improvig the FEC performace. Iterleavig Operatio: Before packets beig trasmitted ito the etwork, packets are filled ito a M1*M2 Row wise. (a) (b) Fig6: (a) Evaluate iterleavig FEC performace Poisso arrival (b) Evaluate iterleavig FEC performace determiistic arrival. 2. FEC Performace with Multiple Sources (N>1) Here, we proceed to explore the FEC performace i case of multiple sources sharig the multiplexer. I order to facilitate the aalysis, here assume i the packet arrival process see by the multiplexer from each source is Poisso. Fig 5: Illustratio of block iterleavig operatio (iterleavig depth=m1). The above fig shows the case of determiistic arrivals(h= ) with all other system parameters the same as i Fig. 6 FEC Performace without Iterleavig: I order to evaluate the FEC performace for oe of the N sources, the block-error distributio P(. For a sigle isolated source is required. Here we discuss differet method to compute Copyright to IJARCCE

7 P( for the N*M/M/1/K. queue, which ca be exteded easily to icorporate the aalysis for iterleavig. Aalysis of Block-Error Distributio for a Sigle Source: Assume the packets arrivig at the sigle-multiplexer come from N idepedet sources: S1, S2 S. idicates that, for N homogeeous sources with a fixed overall load ρ, the loss process of a sigle source becomes less ad less correlated with icreasig N Fig7. FEC performace with N homogeeous sources; Poisso arrivals, load from each source fixed at ρi =0.02, K=10 block size =63 from each source is fixed while the total load ρ = λ/μ chages with varyig N. FEC Performace with Iterleavig: Now we suppose the packets from each homogeeous source are iterleaved with the same iterleavig depth before beig trasmitted ito the etwork. The algorithm for computig the block-error distributio P( for a sigle source ca be exteded to iclude the iterleavig procedure, as provided i previous Sectio. It ca be expected that, compared to the case of a sigle source (N=1), the eed for iterleavig will be sigificatly reduced i a multiplexig eviromet (N 2), due to the already reduced packet-loss correlatio as a result of the atural iterleavig effect of multiplexig. Fig. 8 shows the to the already reduced packet-loss correlatio as a result of the atural iterleavig effect of multiplexig Depths, where the umber of sources is N = 3 ad the total system load is fixed at ρ =0.8 (Sceario 1) with buffer size K = 10. As expected, whe, i order to optimize the FEC performace, a iterleavig depth M 10 is required, Fig8. Multiplexig gai achieved by FEC codig with differet codig block sizes ; Poisso arrivals, the effective packet-loss rate fixed at PLReff= 10-6, load from each source fixed at ρi=0.02,k=10 Now look at the FEC performace i improvig the Statistical multiplexig gai. Suppose the FEC coder for each homogeeous source applies a RS(,k)code to the packets from the correspodig source coder. The chael codig rate remais Rc = k/. As a result of the chael codig, the packet arrival rate ito the sigle-multiplexer will icrease to λ 1 = λi/rc. We assume that the average load Fig9. Effect of iterleavig o FEC performace with N=3 sources; Poisso arrivals, total load fixed at ρ = 0.8, K = 10, =63. FEC performace with differet umbers of sources N for a give total load ρ=0.8. It shows that whe the umber of sources N icreases, the eed for iterleavig depth decreases, which meas reduced latecy associated with the iterleavig/de-iterleavig operatio. Whe N 14, iterleavig makes a isigificat differece i FEC performace, because i this case the packet-loss process of each source is early idepedet. 3. Potetial of FEC Chael Model for Packet Trasmissio over Networks: Cosider a chael model for packet trasmissio over a geeral packet-switched etwork. Assume a packet has M- bits. It is either trasmitted ad received by the receiver, or is lost due to etwork cogestio or buffer overflow. For a Copyright to IJARCCE

8 received packet, bit errors may be itroduced. The packet trasmissio over etworks ca be modeled for codig purpose i terms of serial bit by bit trasmissio of M-bit symbols either over a biary symmetrical chael (BSC) with crossover probability ρ (state 0) or over a biary erasure chael (BEC) (state1), Both of which are illustrated i Fig. 10 where ǿ is used to idicate the erasure symbol. A lost packet correspods to the etire codeword symbol of m bits beig erased, while a received packet meas each of the m bits is sequetially trasmitted over the BSC. This chael model belogs to the class of Block Iterferece Chaels probability p=0. Let PL be the packet loss rate of the siglemultiplexer, so p= PL. The C=(1-p)*(1-H(p))=1- PL Assume the source creates packets at rate λ ad the packet service rate is μ. The the ormalized system load before codig is ρ = λ/μ. The chael ecoder applies chael codig (ot ecessarily RS codes) with codig rate Rcto the source traffic. Fig10. Compoet chaels of BIC correspodig to packet delivery ad loss. Fig11. Simplified commuicatio system model. Block Iterferece Chaels (BIC), itroduced by McEliece ad Stark. Let S {0,1} represet the state space of the BIC. If the state trasitios are idepedet, the the Shao capacity of the BIC is give as, C = Es{Cs}; bits/trasmissio Where Cs is the capacity of the compoet chael s S, ad the expectatio is over the state space S. It Follows that C = (1-ρ) * (1-H(p)); bits/trasmissio, Where ρ is the probability of beig i the loss state ad H(p) is the biary etropy fuctio, H(p) = -p log p-(1-p) log (1-p); 0 p Iformatio Theoretic Boud O FEC Suppose the iterleavig is ideal, ad cosequetly the packet-loss process see by the chael decoder is idepedet. If we cosider the iterleaver ad the deiterleaver as compoets of the codig chael, the the chael, cosistig of the iterleaver, the sigle-multiplexer ad the de-iterleaver, ca be modeled as a BIC with idepedet state trasitios Here we cosider oly the packet losses caused by the buffer overflows, ad assume o bit errors, i.e., the BSC crossover Fig12. Schematic illustratio of the fuctioal relatioship C =1 f ( ρ / Rc ), for differet values of ρ with ρ1 ρ 2 ρ3. The the ormalized system load after codig will icrease to ρ1 = ρ/rc. Give the buffer size K, the average raw packet loss rate PL depeds oly o the load ρ1, as expressed by PL = f(ρ1 ) = f(ρ / Rc) Where the fuctio f ca be determied by queuig aalysis of the sigle-multiplexer model C = 1 - PL = 1 f(ρ / Rc) For a give load, we ca plot the fuctioal relatioship of C with Rc. The chael codig theorem establishes that ay rate less tha the chael capacity ca be supported with arbitrary low error probability. I other words, with regards to our model discussed here, as log as the chael codig rate Rc is smaller tha the BIC capacity C, the source rate ca be supported with arbitrarily high reliability. Fig13. The upper boud o the source loads ρ max predicted by the chael capacity cosideratios, compared to the Copyright to IJARCCE

9 maximum source loads ρ max that ca be supported at a fixed effective packet-loss rate PLR eff = 10-5 usig FEC codig; Poisso arrivals, ideal iterleavig, For the M/M/1/K model shows the upper boud o the source loads that ca be supported as predicted by the precedig chael capacity cosideratios. It shows that with icreasig codig block size the ed-to-ed performace achieved by FEC codig approaches that predicted by chael capacity. Fig14. The upper boud o the source loads ρ max predicted by the chael capacity cosideratios, compared to the maximum source loads ρ max that ca be supported at a fixed effective packet-loss rate PLR eff = 10-5 usig FEC codig; Poisso arrivals, ideal iterleavig, usig FEC codig; Poisso arrivals, ideal iterleavig, K = 5. The case of a smaller buffer ( K = 5). The two figures idicate that, geerally, the system with a larger buffer has a larger capacity. Note that i these two figures the capacity C is the capacity of the sigle-multiplexer combied with a ideal iterleaver/de-iterleaver, ad ot the capacity of the sigle-multiplexer itself. Actually, the capacity of the sigle-multiplexer chael ca be greater tha C described here sice the capacity of the memory less iterleaved chael is geerally lower tha the capacity of the origial chael. 5. Coclusio As the above aalysis o the efficiecy of FEC i packet losses i etworks based o a sigle-multiplexer etwork model ad explored potetiality of the FEC i recoverig the packet losses occurred due to cogestio at a bottleeck ode of a packet-switched etwork, provided that the codig rate ad other codig parameters are appropriately chose. A discrete-time Markov chai model is used to aalyse the efficacy of iterleavig i improvig the FEC performace ad determied how much iterleavig depth is required for FEC to approach the optimum performace. The implemetatio complexity of FEC codig ad the correspodig codig/decodig delay also eed to be cosidered, which a issue particularly importat for realtime applicatios. Oe objective for future work is the aalysis of the additioal delay caused by the FEC codig, perhaps combied with iterleavig/de-iterleavig. Likewise, the applicatio of FEC for etwork trasport is limited by the time-varyig ad ofte ucertai error characteristics of the chael, which makes the appropriate choice of FEC codig rate difficult to determie. I realworld applicatios, FEC coders are required which ca adapt the chael code rate to the time-varyig chael coditios. 7. Refereces [1] O. J. Boxma, Sojour times i cyclic queues The ifluece of the slowest server, i Proc. 2d It. MCPR Workshop o Computer Performace ad Reliability, Rome, Italy, May [2] D. Y. Eu ad N. B. Shroff, Network decompositio: Theory ad practice, IEEE/ACM Tras. Networkig, vol. 13, o. 3, pp , Ju [3]D. Gross ad C. M. Harris, Fudametals of Queuig Theory, 3 rd ed. New York: Wiley, [4]I. Cido, A. Khamisy, ad M. Sidi, Aalysis of packet loss processes i high-speed etworks, IEEE Tras. If. Theory, vol. 39, o. 1, pp , Ja [5] A Model-Based Approach to Evaluatio of the Efficacy of FEC Codig i Combatig Network Packet Losses Xuqi Yu, Studet Member, IEEE, James W. Modestio, Fellow, IEEE, Ragip urcere, Member, IEEE, ad Yee Si Cha, Member, IEEE [6] V. Parthasarathy, J. W. Modestio, ad K. S. Vastola, Reliable trasmissios of high-quality video over ATM etworks, IEEE Tras. Image Process., vol. 8, o. 3, pp , Mar [7] A. Jea-Marie, P. Dube, D. Artiges, ad E. Altma, Decreasig loss probabilities by redudacy ad iterleavig: A queueig aalysis, i Proc. ITC 18, Berli, Germay, Sep BIOGRAPHY Kaakam Siva Ram Prasad pursuig M.Tech i computer Sciece ad Egieerig from Sasi Istitute of Techology ad Egieerig, affiliated to Jawaharlal Nehru Techological Uiversity Kakiada. His research areas iclude reducig the data loss i etworks by applyig the Forward Error Correctio codig. M.V.S.S.Nagedhraadh havig 11 years of teachig experiece curretly workig as Head Of the Departmet for CSE i Sasi Istitute of Techology ad Egieerig curretly pursuig PhD i computer sciece ad graduated i M.Tech CSE. He has published five iteratioal jourals ad also atteded to three iteratioal cofereces. Copyright to IJARCCE