EE 333, Communication Networks Quiz-I (2014-15S)

Maximum Marks = 10 Time=45 minutes

1. Both A and B have a copy of a packet which they can send to D using the links A-D and B-D, respectively. Assume that the packet is of total duration T and the links and the packet error probability on both the links is P. Assume that both A and B start their transmission at time t and continue transmitting together (repeating the packet) until D gets the packet (either from A or from B) at time kT. Find the distribution of k and its mean. [3+3]

2. Consider the CRC-8 polynomial 8 2 1x x x (a) Summarize its error detection properties. State clearly whatever other assumptions you need to make. [2] (b) Give the circuit using shift registers that can be used to divide an arbitrary polynomial by this CRC-8 polynomial and (very) briefly describe its operation. [2]