0 — Test 393

Correct Answer: A. A. Total float
Explanation: Total float is the additional time available for non-critical activities without delaying the project duration. It may affect the floats of both the succeeding activities as well as preceding activities.

Correct Answer: D. D. 2 minutes
Explanation: We know that, Total float = Latest start time (LST) – Earliest start time (EST) (or) Latest finish time (LFT) – Earliest finish time (EFT) Total float = 12 – 10 = 2 minutes.

Correct Answer: A. A. 4 minutes
Explanation: We know that, Free float = Earliest start time (EST) of the head event – Earliest start time (EST) of the tail event – activity duration Free float = 10 – 2 – 4 = 4 minutes.

Correct Answer: B. B. A-e-f
Explanation: Critical activities are denoted using a thick arrow or by an arrow with double solid lines. In the given network diagram, activities A-E, E-F are critical activities. Hence, path A-E-F is the critical path.

Correct Answer: D. D. Application policies
Explanation: The various characteristics of the unused spectrum bands determined during spectrum sensing depend on the time-varying radio environment, operating frequency, bandwidth, and quality of service requirements of the cognitive radio user. Spectrum management is required to correctly associate a user to a compatible spectrum band among all available spectrum bands in xG networks.

Correct Answer: D. D. Repair
Explanation: The major functions of spectrum management are spectrum sensing, spectrum analysis, and spectrum decision-making. Spectrum sharing and spectrum mobility are also included in the management framework. Every function operates over all layers of the OSI model except sensing which is implemented only in the physical layer.

Correct Answer: D. D. Spectrum sharing
Explanation: In the unlicensed portion of the spectrum, cognitive radio users have equal access to the spectrum and attempt to access the spectrum simultaneously. Spectrum sharing coordinates the network access such that collision is avoided in overlapping portions of the spectrum.

Correct Answer: C. C. Vacate spectrum band
Explanation: The cognitive radio users only have temporary access to the unused spectrum in the licensed band. If the primary user demands access, the spectrum mobility function of the spectrum management framework intervenes and transfers the cognitive radio user to another vacant position.

Correct Answer: C. C. Match spectrum bands with user requirements
Explanation: Spectrum analysis defines the characteristics of the spectrum bands and verifies whether the characteristics meet the user requirements. Interference level, channel error rate, link-layer delay, holding time, and path loss are few of defining parameters of a spectrum band.

Correct Answer: B. B. Amount of interference at the primary receiver
Explanation: Channel capacity can be estimated by determining the permissible power of an xG user. The permissible power is computed by determining the amount of interference at the primary receiver. The amount of interference sometimes depends on the number of users in the spectrum.