1. (1 pt) PPP (Point-to-Point Protocol) uses character stuffing to mark the frame start and end. Give the characters transmitted for the following data for which the character stuffing algorithm described is used:
DLE STX A DLE B DLE ETX
2. (3 pt) One way of detecting errors is to transmit data as a block of n rows if k bits per row and adding parity bits to each row and column. Sending 9 data bits as a 3x3 block with parity, will this scheme detect all single errors? Double errors? Triple errors? Quadruple errors?
3. (1 pt) Why do data link protocols put the CRC in the trailer?
4. (2 pt) Calculate the polynomial code checksum for the
generator polynomial x3+1 and the data frame 10100001.
5. (1 pt) A 100 km cable runs at 1Mbps rate. The
propagation is 6 msec/km. How many bits fit in the
cable in one direction?
6. (1 pt) How many code bits are required to detect a one bit error in 500 bits?
7. (1 pt) What is the Hamming distance required to correct a one bit error in 500 bits?
8. (1 pt) How many code bits are required to construct a code using Hamming's method that will correct a one bit error in 500 bits?
9. (2 pt) The notes give an example of a one bit
Hamming error correcting code (the example has an error occurring in the 4th
position). Redo the computation of the example for an error in the 5th position.
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