RCDD Wireless Systems Design and Infrastructure 2 — Questions and Answers
Question 1: In a passive DAS (Distributed Antenna System) design, the signal is distributed from the head-end using:
- Active remote units with fiber backhaul
- Coaxial cable splitters and combiners (Correct answer)
- Ethernet switches and PoE injectors
- Multimode fiber with optical amplifiers
Correct answer: Coaxial cable splitters and combiners
A passive DAS uses coaxial cable with passive RF splitters and combiners to distribute antenna signals without amplification at the remote antenna units.
Question 2: Which FCC regulation governs the maximum allowable EIRP (Effective Isotropic Radiated Power) for unlicensed 2.4 GHz 802.11 devices in the United States?
- FCC Part 15 (Correct answer)
- FCC Part 22
- FCC Part 90
- FCC Part 101
Correct answer: FCC Part 15
FCC Part 15 governs unlicensed intentional radiators including Wi-Fi devices operating in the 2.4 GHz and 5 GHz ISM/UNII bands.
Question 3: What is the primary purpose of performing a predictive RF site survey before installing a wireless LAN?
- To physically measure actual signal levels in the finished space
- To model expected coverage and identify AP placement prior to installation (Correct answer)
- To test PoE power delivery from the network switches
- To verify cable continuity in the horizontal cabling plant
Correct answer: To model expected coverage and identify AP placement prior to installation
A predictive (passive) site survey uses RF modeling software to simulate coverage and capacity before installation, enabling optimal AP placement planning.
Question 4: In wireless system design, co-channel interference (CCI) is best mitigated in a 2.4 GHz 802.11 deployment by:
- Using only channels 1, 6, and 11 (Correct answer)
- Deploying all APs on the same channel
- Increasing transmit power on all access points
- Using channels 2, 5, and 8 for non-overlapping operation
Correct answer: Using only channels 1, 6, and 11
Channels 1, 6, and 11 are the only three non-overlapping channels in the 2.4 GHz band, minimizing co-channel interference when used in adjacent cells.
Question 5: According to ANSI/TIA-4965, what type of outlet is used to serve a wireless access point location and provides both data connectivity and power?
- Multiuser telecommunications outlet assembly (MUTOA)
- Consolidation point (CP)
- WAP outlet with PoE-capable port (Correct answer)
- Zone distribution frame (ZDF)
Correct answer: WAP outlet with PoE-capable port
ANSI/TIA-4965 specifies that WAP locations be served by an outlet supporting PoE, providing both data and power to the access point through the structured cabling.
Question 6: An active DAS differs from a passive DAS primarily because active DAS uses:
- Only coaxial cable for signal distribution
- Remote units that amplify and regenerate the RF signal (Correct answer)
- A single omnidirectional antenna for the entire building
- Unlicensed spectrum exclusively
Correct answer: Remote units that amplify and regenerate the RF signal
Active DAS employs remote units (RUs) that convert, amplify, and re-radiate the RF signal, enabling coverage over much larger distances than passive splitter-based systems.
Question 7: What BICSI-recommended metric defines the minimum acceptable signal strength (RSSI) for voice-grade Wi-Fi calling applications in an enterprise wireless design?
- -80 dBm
- -70 dBm
- -67 dBm (Correct answer)
- -55 dBm
Correct answer: -67 dBm
-67 dBm is the widely accepted minimum RSSI threshold for voice-grade Wi-Fi, as it provides sufficient signal margin for low-latency, low-jitter wireless voice communications.
RCDD Wireless Systems Design and Infrastructure 2
In a passive DAS (Distributed Antenna System) design, the signal is distributed from the head-end using: