CS 3413 Data Communications, Fall 2004 Practice Problems
- What is the period of cos23t?
- What is the wavelength of a 2 GHz signal in empty space?
- The index of refraction of water is about 4/3. What is the wavelength
of a 2 GHz signal in water?
- What is the maximum data rate if 16 signal levels are used over a
telephone line with a bandwidth of 4 kHz?
- What is the maximum data rate of a telephone line with a bandwidth of
4 kHz and a signal-to-noise ration of 30 dB?
- Stereo music having a frequency range up to 20,000 Hz is to be converted
to PCM using 14 bits per channel. What data rate is needed in bps?
- What is the Hamming distance of a code that has an 8-bit message and
1 parity bit?
- A code has an 8-bit message and 2 parity bits. The first 4 message bits
are checked with one of the parity bits and the last 4 are check with the
other one.
- What is the efficiency of the code?
- What is the maximum number of bits that can be in error and always
detected?
- What is the Hamming distance of this code?
- Can this code correct single-bit errors? Explain.
- A message has 16 bits. Each bit has a probability of .99 of being correct.
- What is the probability that there are no errors in the message?
- What is the probability that there is at most one bit in error in
the message?
- A stop-and-wait protocol is used to send 2000-bit frames over a channel
with a data rate of 100 kbps.
- What is the maximum efficiency of this protocol?
- If the 1-way propagation delay is 100 ms, what is the efficiency
of the protocol?
- If the timeout is set to 1 second and the 1% of frames and 1% of
acks are lost, what is the efficiency of the protocol?