HW #2

Note: Due on April 20.

1.A series of information frames with a mean length of 100 bits is to be
  transmitted across the following data links using a stop-and-wait ARQ
  protocol. If the velocity of propagation of the links is 2 x 108 m/s,
  determine the link efficiency (utilization) for each type of link.

   a.A 10 km link without errors, with a BER of 10-4 and a data transmission
     rate of 9600 bps 
   b.A 500 m link without errors, with a BER of 10-6 and a data transmission
     rate of 10 Mbps.

  What do you infer from this exercise?

2.Specifications for data link protocols may be defined by finite state
  machines (FSM) of the source (transmitter) and receiver. Assume the following
  two states for each of the source and receiver for Go-back-N ARQ:

     Source: (1) Idle and
             (2) Data (data being transmitted)

   Receiver: (1) Data (RRN ACK sent, data frame ready to be received) and 
             (2) Error (REJN sent, waiting for Frame N)

 Draw the FSM for both source and receiver protocol machines. You are not
 asked to draw the FSM for the total system.

3.A 3000-km long T1 trunk (1.536 Mbps, excluding the framing bit) is
  used to transmit 64-byte frames using go-back-n protocol. If the propagation
  speed is 6 microseconds/km, how many bits should the sequence numbers be?