Q2 (a) Suppose a transmission channel operates at 5 Mbps with a bit error rate of 10%. Bit errors occur at random and independent of each other. Suppose that the following code is used. To transmit a binary 1, the codeword 111 is sent; To transmit a binary 0, the codeword 000 is sent. The receiver takes the three received bits and decides which bit was sent by taking the majority vote of the three bits. Find the probability that the receiver makes a decoding error (wrongly decode 1 as 0 and vice versa). (4 marks) (b) Computer A uses the Go-back-N ARQ protocol to send a 100M byte file to computer B with a window size of 10. If each frame carries 250K byte data, how long does it take to send the file if the distance between A and B is 4000 km and the propagation speed is 2 x 108 m? Given that the transmission rate of the link is 1 Gbps. Assume no data or control frame is lost or damaged and ignore the overhead due to header and trailer. (5 marks) Suppose the following sequence of characters (each character is represented by two hexadecimal digits) arrives over an PPP link: 7E 3F78 24 7A 2B1B1B1B1B7E 87 A3 BC4C 21 1B1B 1B7E 23 56 FD 97 E8 1B 7E 1B 1B 1B 7E FF 34 45 7E FF 1B 7E 2C 1D 1B 1B 7E Given that the Flag and Esc character are (7E) and (1B) respectively. Determine how many frames received and the content of each frame. (6 marks) (d) Suppose that a 2600-Mbps 802.11 ac wireless LAN is transmitting 512-byte frames (5 marks) back-to-back over a radio channel with a bit error rate of 10. How many frames per second will be damaged on average? Q2 (a) Suppose a transmission channel operates at 5 Mbps with a bit error rate of 10%. Bit errors occur at random and independent of each other. Suppose that the following code is used. To transmit a binary 1, the codeword 111 is sent; To transmit a binary 0, the codeword 000 is sent. The receiver takes the three received bits and decides which bit was sent by taking the majority vote of the three bits. Find the probability that the receiver makes a decoding error (wrongly decode 1 as 0 and vice versa). (4 marks) (b) Computer A uses the Go-back-N ARQ protocol to send a 100M byte file to computer B with a window size of 10. If each frame carries 250K byte data, how long does it take to send the file if the distance between A and B is 4000 km and the propagation speed is 2 x 108 m? Given that the transmission rate of the link is 1 Gbps. Assume no data or control frame is lost or damaged and ignore the overhead due to header and trailer. (5 marks) Suppose the following sequence of characters (each character is represented by two hexadecimal digits) arrives over an PPP link: 7E 3F78 24 7A 2B1B1B1B1B7E 87 A3 BC4C 21 1B1B 1B7E 23 56 FD 97 E8 1B 7E 1B 1B 1B 7E FF 34 45 7E FF 1B 7E 2C 1D 1B 1B 7E Given that the Flag and Esc character are (7E) and (1B) respectively. Determine how many frames received and the content of each frame. (6 marks) (d) Suppose that a 2600-Mbps 802.11 ac wireless LAN is transmitting 512-byte frames (5 marks) back-to-back over a radio channel with a bit error rate of 10. How many frames per second will be damaged on average
