3213Assignment2 - −4 for the communication channel Repeat...

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1 CSE 3213, Fall 2009 Exercise 2 Question 1: If the ratio of error detection bits (EDB) to payload bits remain constant, what are the tradeoffs between: (a) having the error bits applied to smaller blocks of data, i.e. spread out over the sequence (see Figure 1), vs. (b) having the error bits applied to bigger blocks of data (see Figure 2). Figure 1 Figure 2 Question 2: Suppose a header consists of the following bits: 11111111 11111111 11111111 00000000 11110000 11110000 11000000 11000000 Find the 16-bit Internet checksum for this code. Question 3: A telephone modem is used to connect a personal desktop to a host computer. The speed of the modem is 56 kbps and the one-way propagation delay is 100ms. (a) Find the efficiency of the stop-and-wait ARQ if the information frame size is 256 bytes with 8 bytes of overhead. Assume the length of the ACK frame is 8 bytes and a bit error rate of 10
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Unformatted text preview: −4 for the communication channel. Repeat for a frame size of 512 bytes. (b) Repeat (a) for the Go-back-N ARQ if three-bit sequence numbering is used with frame size of 256 bytes assuming a bit error rate of 10 − 5 . Repeat (b) for the Selective Repeat ARQ. Question 4: Two neighboring nodes (A and B) use the selective-repeat ARQ with a 3-bit sequence and a window size of 4 at the transmitter and receiver. Assuming A is transmitting and B is receiving, show the content of the window and the positions of the respective pointers at both nodes A and B for the following succession of events. (a) Before A sends any frames. (b) After A sends frames 0, 1, and 2; B acknowledges 0 and 1, and both ACK’s are received by A. (c) After A sends frames 3, 4, and 5; B acknowledges 4, and the ACK is received by A....
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This note was uploaded on 12/11/2010 for the course CSE 3213 taught by Professor A during the Fall '10 term at York University.

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