MIMO_tasks

Massive MIMO

Exercise 1. Answer the following questions:

1.What is this article focused on?

2.How are the antenna arrays used in massive MIMO systems?

3.According to the author, how will massive MIMO facilitate future broadband networks and digital infrastructure?

4.What is the working principle of conventional MIMO systems?

5.How can massive MIMO systems increase the capacity?

6.In what way do massive MIMO systems rely on the law of large numbers?

7.* There are several problems of communication theory mentioned in the article that need research. In your opinion, which of them need additional research the most? Why?

Exercise 2. Give Russian equivalent of the following sentences:

1.In conventional MIMO systems such as the Long Term Evolution (LTE) standard, the base station sends out pilot waveforms, based on which the terminals estimate the channel responses, quantize the thus obtained estimates, and feed them back to the base station.

2.The attractiveness of maximum ratio combining (MRC) compared with ZF is not only its computational simplicity — multiplication of the received signals by the conjugate channel responses — but also that it can be performed in a distributed fashion, independently at each antenna unit.

3.Massive MIMO reduces the constraints on accuracy and linearity of each individual amplifier and RF chain.

4.Due to the scarcity of bandwidth, spreading information over frequency just is not feasible, so the only way of improving robustness of wireless communications is to use multiple antennas.

5.While the concepts of massive MIMO have been mostly theoretical so far, stimulating much research particularly in random matrix theory and related mathematics, basic testbeds are becoming available, and initial channel measurements have been performed.

Exercise 3. Fill in the gaps:

1.The capacity _________ from the aggressive spatial multiplexing used in massive MIMO.

2.The prediction in Fig. 3 is based on an information-theoretic analysis that takes into account

_________, as well as the _____________ of using pilots to acquire channel state information in a high-mobility environment.

3.This matters, because the ____________ of cellular base stations is a growing concern worldwide.

4.Due to the ___________, spreading information over frequency just is not feasible, so the only way of improving ___________of wireless communications is to use multiple antennas.

5.On the downlink, there is enormous potential for ingenious ____________.

Exercise 4. Decide if the following statements true or false:

1.Massive MIMO systems use antenna arrays that serve up to ten terminals.

2.The number of channel responses is also proportional to the number of base station antennas.

3.Fading helps to build low-latency wireless links.

4.Massive MIMO decreases the robustness against both unintended man-made interference and intentional jamming.

5.The typical coaxial cables used for tower-mounted base stations today are more than 4 cm in diameter.