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Cellular Telephony: Multi Antenna Techniques

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Cellular Telephony: Multi Antenna Techniques

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Questions and Answers

What is the purpose of an encoder in a MIMO system?

To amplify the signal before transmission
To filter out noise from the signal
To decode the received signal
To convert the signal into a format suitable for transmission (correct)

What is the assumption made about the wireless propagation channel in a MIMO system?

It is fast-fading and frequency-flat
It is frequency-selective and fast-fading
It is quasi-static and frequency-flat (correct)
It is static and frequency-selective

What type of MIMO channel model is based on electromagnetic wave propagation?

Stochastic model
Physical model (correct)
Analytical model
Deterministic model

What is the main reason for the difference in performance between AWGN channels and Rayleigh fading channels?

The fading of the channel (D) Signup and view all the answers

What is the minimum SNR required to achieve a BER of 10^-4 in AWGN channels?

10 dB (C) Signup and view all the answers

What is the role of the transmit antennas in a MIMO system?

To send the signal through the wireless channel (B) Signup and view all the answers

What is the principle of diversity in wireless communication systems?

To ensure that the same information reaches the RX on statistically independent channels (D) Signup and view all the answers

What is the characteristic of a quasi-static channel?

The coherence time of the channel is long enough to transmit a large number of bits (A) Signup and view all the answers

What is the purpose of phase shifting in a MIMO system?

To make phase correction equal (D) Signup and view all the answers

What is the effect of fading on the BER in wireless communication systems?

It makes the BER decrease linearly with the SNR (D) Signup and view all the answers

What is the purpose of using diversity in wireless communication systems?

To make sure that the SNR has a smaller probability of being low (C) Signup and view all the answers

What is the condition required for uncorrelated Rayleigh channels?

When the antenna spacings and/or the angular spreading of the energy at both sides of the link are large enough (C) Signup and view all the answers