1. Answer the following questions concerning error detection: 1.1 A receiver receives a message containing redundant bits for error checking and uses those bits to determine that no error has occurred. What does the receiver then do with the redundant bits? a. passes them to the next layer up in the network model at the receiver b. saves them for future use c. discards them d. returns them to the sender 12Assume odd parity. If a receiver receives data 10111010 and a parity bit of 1, will it accept it? a. yes b. no c. cannot be determined 1.3.cao,single-bit parity detect an error that flips exactly two data bits? a. Nob . Yes c. Sometimes it depends on the data 14 The checksum for 1000 bytes of data is 16 bits long. Assuming the game checksum algorithm is used, how long will the checksum be for 2000 bytes of data? a. 32 bits b. 16 bits c. 8 bits d. cannot be determined L A CRC divisor is 5 bits long. How long is the checksum? a. 4 bits b. 5 bits c. 6 bits d. cannot be determined 1.6 In cyclic redundancy checking, what is the CRC? a. the divisor b. the quotient c. the dividend d. the remainder 1.7 Which error detection method can detect a single-bit error? a. single bit parity check b. checksum c. CRC d all of the above 2. Assume 4-bit wide units of data. Calculate the checksum for 1011 1001 3. Assume a bit sequence of 10110 and a divisor of 1001. a. Generate the CRC b. Check the CRC 4. A CRC divisor is 11001001. What is the polynomial? suhula what kind of multiplexing does each sender use some of the bandwidth of the link 2. FDM 6. TDM c. both of these d. neither of these 3.2. What scheme multiplexes digital signals? a FDM b. TDM c. both of these d. neither of these 5.3 What is the purpose of a guard band? a. It performs error checking in TDM b. It prevents interference between channels in FDM c. It prevents interference between channels in TDM d. It provides analog modulation 6. What is the minimum bandwidth of the output of a FDM multiplexer that combines 4 channels of 4KHz each? Assume 500Hz guard bands. 7. Three FDM multiplexers are connected as shown below. If each input has a bandwidth of 20 MHz, what is the minimum bandwidth of the output from the second-stage multiplexer? Assume a 3 MHz guard band between channels. 8. Design a hierarchical TDM system to multiplex 10 channels, each with a 3 Mbps bandwidth, together. Assume each multiplexer can combine, at most, 3 channels. Sketch your design, showing the minimum bit rate of the output from the last stage multiplexer. 9. Define a random-access protocol and provide one example of a random-access protocol
