THEORY EXAMINATION (SEM–VIII) 2016-17 ELECTRONIC SWITCHING

SECTION – A

Attempt all parts (Short Answer Type)

Automatic exchange is a telephone switching system where calls are connected automatically without human operators, while manual exchange requires operators to connect calls manually using switchboards.

Voice traffic refers to continuous analog communication such as telephone conversations, whereas data traffic consists of digital information transmitted in packets over networks.

In-band signalling uses the same communication channel for both voice and control signals, while out-band signalling uses a separate channel for control information.

The HDLC frame structure consists of flag fields, address field, control field, information field, and frame check sequence.

A two-motion selector is a switching device used in telephone exchanges that can move both vertically and horizontally to establish connections.

Grade of Service (GOS) is a measure of the probability that a call will be blocked or delayed due to network congestion.

Average occupancy refers to the proportion of time a switching system remains busy handling calls.

Segregation in switching refers to separating different types of traffic within a communication network.

Blocking probability is the likelihood that a call cannot be connected due to insufficient network resources.

Cross points are switching elements that connect input lines to output lines in multi-stage switching networks.

Questions (Section A)

What is automatic exchange?

Define voice traffic.

What is in-band signalling?

Define GOS.

What is blocking probability?

SECTION – B

Attempt any five (Long Answer Type)

Blocking probability in switching networks can be calculated using Lee graph, which represents connections between inputs and outputs. Jacoubeus method is another approach for analyzing blocking in switching systems.

Birth-death process describes the arrival and departure of calls in telecommunication systems. It helps analyze traffic flow and network congestion.

Common channel signalling uses a dedicated channel for transmitting control information. SS7 architecture supports high-speed and reliable signalling in telephone networks.

Erlang B formula calculates the probability of call blocking when no waiting queue is available, while Erlang C formula considers waiting calls.

ATM switches transmit data in fixed-size cells. VPI and VCI are identifiers used to route these cells in ATM networks.

Stored Program Control (SPC) systems can be centralized or distributed based on control unit placement.

SPC software includes operating software, application software, and maintenance software.

Memory-space switches store data temporarily in memory before routing it through switching networks. Banyan networks provide efficient switching paths.

Questions (Section B)

Explain Lee graph method.

What is birth-death process?

Explain SS7 architecture.

Compare Erlang B and Erlang C formulas.

What is ATM switch?

SECTION – C

Attempt any two (Detailed Explanation)

Reed-relay switches use electromagnetic relays for switching operations in telephone systems. General trunking diagrams show how communication lines connect between exchanges.

Markov process is a mathematical model where future states depend only on current states. It is used to analyze telecommunication traffic.

X.25 is a packet switching protocol, while frame relay provides faster data transmission with reduced error checking. SS6 is a signalling system used for communication control.

Questions (Section C)

What is reed-relay switch?

Explain Markov process.

What is frame relay?