. Calculate the overhead associated with the following transmission schemes:
a. Asynchronous transmission; 8 data bits, 1 start bit, 1 stop bit
b. Asynchronous transmission; 7 data bits, 1 start bit, 1 stop bit
c. Asynchronous transmission; 7 data bits, 2 start bits, 1 stop bit, 4 bit FCS
d. Synchronous transmission; 1000 bit data field, 8 bit preamble and 8 bit post amble
e. Synchronous transmission; 2000 bit data field, 8 bit preamble and 24 bit post amble.
8. Show a time sequence diagram for the following scenarios:
a. Stop-and-wait ARQ, frames 0,1, and 2 are transmitted successfully and frame 3 is in error and a successful resend of frame 3 occurs.
b. Go-back-N ARQ, frames 0,1,2 and 3 are sent. Frames 0,1, and 3 are received error free. Frame 2 is in error. Show the subsequent error correction.
Let us assume that 1000 bytes are required to be send at a transmission channel having speed of 100 bps.then the over head in the terms of time and bits can be calculated in the following manner.
a)Asynchronous transmission; 8 data bits, 1 start bit, 1 stop bit
(i) each bit we have overhead of 2bits.
(ii)now total overhead in bits= 1000 * 2=2000 bits
overhead in time=2000/100= 20 ...
The solution examines transmission schemes and time sequence diagrams. The stop-and-wait ARQ frames are provided.
Time Sequence diagrams
Please reference this figure for the question:
55. Draw 3 time sequence diagrams that illustrate the flow of frames between points B and G in Figure 1 using the following information:
a. Stop and Wait ARQ, SENDER sends four frames (F1, F2, F3, and F4). F1, F2 and F4 are received error free, but F3 is lost in the network during its initial transmission. Continue the diagram until all frames are received are error free and properly acknowledged.
b. Go-Back-N ARQ, SENDER sends five frames (F1, F2, F3, F4, and F5). F1 through F2 are received error free but F3 is lost in the network after F4 and F5 are sent. Assume that F4 and F5 are received error free. Continue the diagram until all frames are received error free and properly acknowledged.
c. Selective Reject ARQ, SENDER sends six frames (F1, F2, F3, F4, F5 and F6) but only has a four frame send window. F1,F2 and F4 are received error free but an error is detected in F3 after F4 is received. When sent F5 is received error free while F6 is lost in the network. Continue the diagram until all frames are received error free and properly acknowledged.View Full Posting Details