Miniquiz, CIS451, 11/07/2003.
You know the drill.
Name on every sheet. Feel free to use only this sheet.
10 minutes.

1A. What does ATM stand for?
       Asynchronous Transfer Mode

1B. What does AAL stand for?
       ATM Adaptation Layer.

1C. What does QAM stand for?
       Quadrature Amplitude Modulation


2A. Draw the amplitude - phase diagram of 4-QAM with 1 amplitude 
    and 4 phases.
       (See classnotes for drawing).




2B. Give another name for this scheme.
       QPSK (Quadrature Phase Shift Keying), or
       PSK (Phase Shift Keying), or simply
       Phase Modulation


3.  In HDLC, the pattern  0111 1110 is a flag indicating beginning 
    or end of a frame. (The space is there only for readability).
    Assuming bit-stuffing is used to make sure the flag pattern 
    does not occur in the data:

3A. Stuff the pattern   100101111110111110011111111111100111100

    1001011111010111110001111101111101100111100
              ^       ^       ^     ^

3B  Unstuff the pattern  101111101111101110111110010111100 

    1011111 11111 111011111 010111100  
    (I left spaces where I took the zero out. 
    In reality there are no spaces.)


(Please count carefully!  :-)  ).