Assume that a 12-bit Hamming codeword consisting of 8-bit data and 4 check bits is d₈d₇d₆d₅c₈d₄d₃d₂c₄d₁c₂c₁, where the data bits and the check bits are given in the following tables:

Data bits
d8	d7	d6	d5	d4	d3	d2	d1
1	1	0	x	0	1	0	1

 

c8	c4	c2	c1
Y	0	1	0

Which one of the following choices gives the correct values of x and y?

Consider a 128 × 10³ bits/second satellite communication link with one way propagation delay of 150 milliseconds. Selective retransmission (repeat) protocol is used on this link to send data with a frame size of 1 kilobyte. Neglect the transmission time of acknowledgement. The minimum number of bits required for the sequence number field to achieve 100% utilization is _________.

A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 Kbps (1Kbps = 1000 bits/second). Size of an acknowledgment is 100 bytes and the transmission rate at the receiver is 8 Kbps. The one-way propagation delay is 100 milliseconds. Assuming no frame is lost, the sender throughput is __________ bytes/second.

Suppose that the stop-and-wait protocol is used on a link with a bit rate of 64 kilobits per second and 20 milliseconds propagation delay. Assume that the transmission time for the acknowledgment and the processing time at nodes are negligible. Then the minimum frame size in bytes to achieve a link utilization of at least 50% is _________.