What is a communication resource (CR) ?
It represents the time and bandwidth that is available for communication associated with a given system. The term multiplexing and multiple access refers to the sharing of a CR.
What are the basic ways of communication resources ?
Frequency Division Multiple Access (FDMA)
Time Division Multiple Access (TDMA)
Code Division Multiple Access (CDMA)
What distinguishes each user in a spread spectrum system?
Each user is distinguished by its own PRBS (Pseudo-Random Binary Sequence) code.
What must be done with the PRBS in the receiver (RX)?
It must be synchronously generated.
Rough synchronization = acquisition
Fine synchronization = tracking
FDMA divides signals into:
A. Subcarriers
B. Pixels
C. Packets
D. Frames
Answer: A
A guard band prevents:
A. ISI
B. Adjacent-channel interference
C. Modulation
D. Fading
Answer: B
Multiple access allows:
A. Many users to share the medium
B. More noise
C. Only one user
D. No synchronization
Answer: A
TDMA requires:
A. Timing synchronization
B. Encryption
C. A-law coding
D. Frequency hopping
Answer: A
CDMA codes must be:
A. Correlated
B. Nearly orthogonal
C. Identical
D. Unused
Answer: B
FDMA channels are separated by:
A. Guard bands
B. Time gaps
C. Bit parity
D. Pilots
Answer: A
OFDMA is widely used in:
A. LTE
B. GSM
C. AM radio
D. Ethernet
Answer: A
