## NPTEL 5G Wireless Standard Design Week 8 Assignment Answers 2024

1.

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2. Signals that are required to estimate the channel to find the desired precoding matrix for transmitting the downlink signal.

- DMRS
- CSI-RS
- SRS
- PDCCH

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3. If the UE has 4 antennas and gNB has 16 antennas then calculate the number of CSI-RS ports that gNB should configure so that the UE can estimate the unprecoded channel.

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4. If the UE has 1 antenna and the gNB has 64 antennas then calculate the number of CSI-RS ports that gNB should configure so that the UE can estimate the precoded channel.

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5. Consider a system where gNB has 32 antennas and UE has 4 antennas and gNB is transmitting a 32 port CSI-RS signal to calculate the MCS value. If the effective SINR of the received signal across the 4 antennas at UE are 2dB, 3dB, 2.5dB and 1.5dB. Calculate the MCS index that UE will report for optimal PDSCH transmission.

**Note: **Please refer to Table 5.1.3.1-2: MCS index table 2 for PDSCH of TS38.214 v15.3.0 to find the MCS index.

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6. Which of the following statements are true regarding CSI-RS signals

- Number of CSI-RS ports and physical antennas at gNB should be always same
- CSI-RS report is sent to gNB using either PUCCH or PUSCH transmission.
- gNB needs to know the MCS from CSI-RS report for transmitting the PDCCH signal.
- gNB can use the appropriate precoder to transmit the CSI-RS signal after sounding the un-precoded channel using SRS.

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7. If the UE has 4 antennas and gNB has 16 antennas then find the maximum number of layers that can be transmitted over the channel.

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8. Which of the following statements are true

- gNB can use SRS to estimate the un-precoded channel
- gNB uses the DMRS signal to find the precoder matrix
- In a MIMO system UE demodulates the data from the precoded channel.
- The rank of the matrix can never be less than min(N
_{T},N_{R})

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9.

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