Group B Ppt

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Group B Ppt

  1. 1. STOP AND WAIT ARQ GROUP B
  2. 2. TEAM MEMBERS GROUP 14: INDIGO  AMULYA GURURAJ 1MS07IS006  BHARGAVI C S 1MS07IS013  MEGHANA N 1MS07IS050  TANUSHREE A G 1MS07IS139 GROUP 21: DYNAMIC NETWORKS  AMEET GONDALI 1MS07IS003  BHUJANG R 1MS07IS016  KAUSHIK N 1MS07IS037  PRAMOD M 1MS07IS070
  3. 3. CONTENTS  Introduction  Stop And Wait ARQ  Sender Algorithm.  Receiver Algorithm  Efficiency  Advantages & Disadvantages  Applications  Demo
  4. 4. INTRODUCTION  Data Communication channels are divided into two major types :-  (a)Noisy Channels.  (b)Noiseless Channels.  Noiseless Channels :- An ideal case channel put forth by Niquest.  Noisy Channel :- Practical case channels , put forth by Shannon.
  5. 5. Continued  Noiseless Channels :- (1) Simplest (2) Stop and Wait  Noisy Channels (1) Stop and wait ARQ (2) Go Back N ARQ (3)Selective Repeat ARQ
  6. 6. STOP AND WAIT ARQ  Design  Implementation .
  7. 7. SENDER ALGORITHM Sn =0 cansend = true; While(true) { WaitForEvent(); If(event(RequesTtoSend) AND cansend) { Getdata(); MakeFrame(Sn); StoreFrame(Sn); SendFrame(Sn); StartTimer(); Sn =Sn+1; Cansend =false; }
  8. 8. SENDER ALGORITHM (CONT..) WaitForEvent(); if( event ( Arrival notification)) { ReceiveFrame(ackno); If(not corrupted AND ackno == Sn) { Stop Timer(); PurgeFrame(Sn-1) cansend =true; } } If(event(Timeout)) { StartTimer(); ResendFrame(Sn-1); } }
  9. 9. RECEIVER SIDE ALGORITHM Rn =0; While(true) { WaitForEvent(); If(event(ArrivalNotification)) { ReceiveFrame(); If( corrupted ( Frame)); Sleep(); If ( seqNo ==Rn) { Extract data(); Deliver data(); Rn =Rn+1; } SendFrame(Rn); } }
  10. 10. EFFICIENCY Performance Analysis of Stop and Wait ARQ Parameters:  TRANSF: Frame transmission time at sender side  TRANSA: ACK transmission time at receiver side  PROP: propagation delay  PROC: Frame processing time  p: Probability of frame error at sender side  q: Probability of frame error at receiver side  TIMEOUT: Sender time out
  11. 11. Calculations  Case 1 : Efficiency in transmitting an error free packet Time taken to transmit an error free packet is: Ts = TRANSF + TRANSA + 2(PROC+PROP) In this case efficiency is: E = TRANSF/Ts This occurs with the probability (1-p)*(1-q)
  12. 12. Case 2: Efficiency in transmitting an error packet The delivery of an error packet takes place with the probability: r = p + (1-p)*q The average packet delay in ARQ scheme is D = TS + TIMEOUT(p/(1-p)) In this case efficiency is: E = TRANSF/D
  13. 13. ADVANTAGES  Simple to implement.  Frames numbering is modulo-2 i.e, only 1 bit is required.  Can be used for noisy channels.  Has both error and flow control mechanism.  Has timer implementation.
  14. 14. DISADVANTAGES  When propagation delay is long, it is extremely inefficient.  Only one frame is sent at a time.  Timer should be set for each individual frame.  No pipelining.  Sender window size is 1( disadvantage over Go back n ARQ).  Receiver window size is 1( disadvantage over selective repeat ARQ).
  15. 15. APPLICATIONS  IBM Binary Synchronous Communications protocol (Bisync): character-oriented protocol  XModem: modem file transfer protocol  Trivial File Transfer Protocol : simple protocol for file transfer over UDP
  16. 16. THANK YOU

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