PC2: Multiple Access

Question 1

Common nodes in a communication network (such as satellites) must be interconnected with all types of users as flexibly as possible

Answer 1

Multiple Access

Question 2

• Assigned bandwidth is divided into segments.
• User operate at the same time, using different frequencies.

Answer 2

Frequency Division Multiple Access (FDMA)

Question 3

• Allocation of specific time slots for transmission.
• Users operate on same frequencies, different times.

Answer 3

Time Division Multiple Access (TDMA)

Question 4

All users transmit signals simultaneously on the multiple access channel.

Answer 4

Code Division Multiple Access (CDMA)

Question 5

The process of combining signals into a composite baseband to modulate on to a single carrier.

Answer 5

Multiplexing

Question 6

A modulation technique used to encode a digital signal in a manner that distributes the transmitted power over a greater bandwidth than the information signal would naturally require.

Answer 6

Spread Spectrum

Question 7

What are the 3 reasons for Spread Spectrum modulation techniques?

Answer 7

1. Low Probability of Detection (LPD)
2. Low Probability of Interception (LPI)
3. Reduces susceptibility to Interference

Question 8

Spread Spectrum uses a greater amount of what?

Answer 8

Bandwidth

Question 9

A digital sequence that is intended to resemble a random succession of ones and zeros

Note: A spread sequence

Answer 9

Pseudo-Random-Noise (PRN)

Question 10

Pseudo-Random Noise (PRN) patterns help hide our signals from adversaries while also allowing what?

Answer 10

Multiple users to use the same frequencies simultaneously

Question 11

The carrier frequency of the transmitted wave changes at regular intervals, based on a pseudorandom sequence

Answer 11

Frequency Hopping Spread Spectrum (FHSS)

Question 12

Uses a Pseudo Random Noise (PRN) code sequence to directly modulate the baseband info, allowing the user to operate below the noise floor.

Answer 12

Direct Sequence Spread Spectrum (DSSS)