Computer Networks / Datenverarbeitung 2 / Data Processing 2 Exercise 7: Network Transmission & Code Efficiency Faculty of
Question 7.1 Code Efficiency Block Length S S S Y Y O N N H 5 characters S T X E S C 2 bytes...... E T B C B C E O X C C T S S Y Y N N Payload Total Block Length B L = SOH + 5 bytes + STX + Payload + ETX+ BCC + BCC+ EOT =1+5+1+150+1+1+1+1=161bytes + 1 + 150 + 1 + 1 + 1 + 1 = 161 Faculty of
Question 7.1 Code Efficiency No. of ESC sequences in payload = = 5 bytes Pure Payload = B L header information ESC sequences in payload = 145 bytes Code Efficiencyi Faculty of
Question 7.2 Optimal Block Length For erroneous transmission: net tare preamble payload trailer gross Payload transfer rate Optimal block length Faculty of
Question 7.2 Optimal Block Length Faculty of
Question 7.3 Code Efficiency STM STX ETX CRC CRC ETM 64 byte audio data (fixed length) Faculty of
Question 7.4 Protocol information vs. data Adding an ESC ESC ETX Adding exception sequence STT and ETT STT ETX ETT Doubling the character ETX ETX Exclude ETX from payload Possible because audio data a is transmitted Faculty of
Question 7.5 Probability of ETX in payload 1 Byte = 8 bits Possible distinct t number of codewords d = 256 The probability that this Byte is ETX Probability that ETX is in the payload Faculty of
Question 7.6 Code Efficiency a. Additional ESC Sequence b. Additional exception Sequence c. Additional ETX d. Exclude ETX from payload Faculty of
Question 7.7 Sampling rate, bit width Voice signal bandwidth Accuracy Sampling rate No. of discrete values To represent 200 discrete values Faculty of
Question 7.8 No. of phone calls Effective Bandwidth No of phone calls Faculty of
Question 7.9 Sender & Receiver reaction Receiver: Discards non-correctable frames Sends NACK or sends nothing at all Sender: Retransmits frame after receiving NACK Faculty of
Question 7.10 No. of Phone calls Error rate No. of transmitted frame per second Effective Bandwidth Faculty of
Question 7.10 No. of Phone calls No. of phone calls transmitted Faculty of