CTA Wireless Communications & Mobile Technologies 2 — Questions and Answers
Question 1: Which cellular network element manages radio resources and controls base stations in a 4G LTE network?
- Mobile Switching Center (MSC)
- Home Location Register (HLR)
- eNodeB (eNB) (Correct answer)
- Packet Data Network Gateway (PGW)
Correct answer: eNodeB (eNB)
In LTE, the eNodeB (evolved Node B) manages radio resource allocation and connects directly to the core network, unlike older architectures with separate controllers.
Question 2: What is the approximate maximum theoretical downlink speed for LTE Advanced (LTE-A)?
- 100 Mbps
- 300 Mbps
- 1 Gbps (Correct answer)
- 10 Gbps
Correct answer: 1 Gbps
LTE Advanced, through carrier aggregation and advanced MIMO, achieves theoretical peak downlink speeds of up to 1 Gbps.
Question 3: In a CDMA system, how are multiple users distinguished on the same frequency channel?
- By time slots
- By unique spreading codes (Correct answer)
- By different polarizations
- By geographic separation only
Correct answer: By unique spreading codes
CDMA assigns each user a unique pseudo-random spreading code, allowing all users to share the same frequency simultaneously.
Question 4: What does OFDMA stand for and what is its key advantage in 5G NR?
- Orthogonal Frequency Division Multiple Access; it allows multiple users to share subcarriers simultaneously (Correct answer)
- Open Frequency Division Multiplexed Access; it reduces latency only
- Outband Frequency Division Modulation Array; it increases range
- Orthogonal Fixed Division Mode Algorithm; it simplifies encryption
Correct answer: Orthogonal Frequency Division Multiple Access; it allows multiple users to share subcarriers simultaneously
OFDMA divides the available spectrum into subcarriers that can be assigned to different users simultaneously, improving efficiency in dense networks.
Question 5: Which unlicensed spectrum band is most commonly used by Bluetooth devices?
- 900 MHz ISM band
- 2.4 GHz ISM band (Correct answer)
- 5 GHz UNII band
- 60 GHz WiGig band
Correct answer: 2.4 GHz ISM band
Bluetooth operates in the 2.4 GHz ISM (Industrial, Scientific, and Medical) band, using frequency hopping to reduce interference.
Question 6: What is the purpose of a Distributed Antenna System (DAS) in telecommunications?
- To replace satellite communication entirely
- To extend wireless coverage within buildings or large venues by distributing antennas throughout the space (Correct answer)
- To increase the transmit power of a single tower
- To connect two separate cellular networks
Correct answer: To extend wireless coverage within buildings or large venues by distributing antennas throughout the space
A DAS uses a network of spatially separated antennas connected to a common source to improve indoor or in-building wireless coverage.
CTA Wireless Communications & Mobile Technologies 2
Which cellular network element manages radio resources and controls base stations in a 4G LTE network?