Satellite Teletraffic Engineering Quiz

Question 1: In satellite teletraffic engineering, what does the term "Erlang" represent?

Correct answer: B - A measure of traffic intensity in a communication system

An Erlang is a unit of telecommunications traffic measurement representing the continuous use of one voice path. It's used to quantify traffic intensity in communication systems.

Question 2: Which parameter is most critical for designing satellite capacity to handle voice traffic?

Correct answer: B - Peak hour traffic volume in Erlangs

The peak hour traffic volume (busy hour traffic) measured in Erlangs is the most critical parameter for dimensioning satellite capacity to ensure quality of service during periods of highest demand.

Question 3: What is the primary purpose of traffic engineering in satellite communications?

Correct answer: B - To optimize resource allocation and meet quality of service requirements

Traffic engineering aims to design, provision, and manage network resources to optimize performance and meet quality of service requirements for different types of traffic.

Question 4: In satellite networks, what does the term "call blocking probability" refer to?

Correct answer: B - The probability that a call request will be denied due to resource unavailability

Call blocking probability is the likelihood that a call attempt will be rejected because all available channels or resources are occupied. It's a key metric in teletraffic engineering.

Question 5: Which traffic model is most commonly used for voice traffic in satellite networks?

Correct answer: B - Erlang B model

The Erlang B model is widely used for voice traffic engineering as it calculates the probability of call blocking in loss systems (where blocked calls are cleared).

Question 6: What is the primary difference between the Erlang B and Erlang C traffic models?

Correct answer: A - Erlang B assumes blocked calls are cleared, while Erlang C assumes blocked calls are delayed

Erlang B models loss systems (blocked calls are cleared), while Erlang C models delay systems (blocked calls are queued until resources become available).

Question 7: In satellite frequency reuse, what is the primary objective?

Correct answer: B - To maximize the utilization of limited frequency spectrum

Frequency reuse allows the same frequency bands to be used in different geographic areas (cells/beams) separated by sufficient distance to limit interference, thereby maximizing spectral efficiency.

Question 8: What does "Grade of Service (GoS)" measure in satellite teletraffic engineering?

Correct answer: B - The probability that a call will be blocked or delayed beyond a specified time

Grade of Service quantifies the probability of a call being blocked (in loss systems) or delayed beyond a specified time (in delay systems), representing the system's ability to handle traffic.

Question 9: Which factor is NOT typically considered in satellite traffic engineering for multimedia services?

Correct answer: C - Satellite orbital velocity

While orbital velocity affects satellite coverage and handovers, it's not a direct parameter in traffic engineering models for multimedia services, which focus on traffic characteristics, QoS requirements, and resource allocation.

Question 10: In satellite networks, what is the main challenge when applying traditional Erlang models?

Correct answer: A - Long propagation delays affecting traffic patterns

Satellite propagation delays (especially in GEO systems) can affect call setup times, acknowledgment mechanisms, and user behavior, which may deviate from assumptions in traditional Erlang models designed for terrestrial networks.

Question 11: Which multiplexing technique is most commonly used in satellite communications to share bandwidth among multiple users?

Correct answer: D - All of the above

Satellite systems employ various multiple access techniques: TDMA (time slots), FDMA (frequency bands), CDMA (code sequences), and SDMA (spatial separation through spot beams) to efficiently share limited satellite resources among users.

Question 12: What is the primary advantage of using demand assignment multiple access (DAMA) in satellite networks?

Correct answer: C - It allocates bandwidth dynamically based on user demand

DAMA systems allocate satellite channels dynamically based on actual user demand rather than using fixed allocations. This improves bandwidth utilization efficiency, especially for networks with bursty or variable traffic patterns.

Satellite Teletraffic Engineering Quiz

Quiz Answers and Explanations