Chapter 11

Question 1

Multiplexing

Answer 1

combining data streams from multiple sources for transmission over shared medium

Question 2

Demultiplexing

Answer 2

separating combined signals back into separate information systems

Question 3

Multiplexor

Answer 3

combines signals from all senders for transmission

Question 4

Demultiplexor

Answer 4

can separate signals for receivers

Question 5

Frequency Division Multiplexing (FDM)

Answer 5

It is possible to send simultaneous multiple carrier (sine) waves, each with different frequency, over single copper wire

Demultiplexor applies filters where each filter extracts small range of frequencies near one of the carrier frequencies

Separate channels correspond to the different carrier frequencies

Frequencies are separated by a guard band

Question 6

FDM Cons

Answer 6

If two frequencies of two channels are close, interference can occur

Demultiplexing hardware must be able to divide signal into separate carriers

Question 7

Hierarchical FDM

Answer 7

Flexibility in FDM is the ability of hardware to shift frequencies.

Question 8

Orthogonal FDM (OFDM)

Answer 8

Specialized FDM, where carrier signals are orthogonal to one another

Question 9

Wavelength Division Multiplexing (WDM)

Answer 9

FDM but for optical fiber where inputs and outputs of such multiplexing are wavelengths of light

Question 10

Time Division Multiplexing (TDM)

Answer 10

Does not rely on special properties of electromagnetic energy.

Question 11

Synchronous TDM vs Statistical TDM

Answer 11

data rate on TDM line is slower than the sum of rates of input lines

problems may occur during peak hours

In synchronous TDM, many slots are wasted (empty)

In statistical or asynchronous TDM slots are allocated dynamically based on demand