What is physical layer in 5G NR?

PHY layer sits at the bottom of the 5G NR protocol stack, interfacing to MAC sublayer higher up via transport channels . It provides its services to MAC and is configured by RRC . PHY supports downlink ( gNB -to- UE ), uplink ( UE -to- gNB ) and sidelink ( UE -to- UE ) communications.

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Is OFDM a modulation?

OFDM in its primary form is considered as a digital modulation technique , and not a multi-user channel access method, since it is used for transferring one bit stream over one communication channel using one sequence of OFDM symbols.

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Why OFDM is used in 4G?

Using multiple carriers, each carrying a low data rate, OFDM is ideal for high speed data transmission because it provides resilience against narrow band fading that occurs as a result of reflections and the general propagation properties at these frequencies .

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How does LTE calculate PRB?

Physical Resource Block (PRB) = 2*Resource Block = 12 Subcarriers x 14 OFDM in 1ms . RE can deliver 2, 4, 6, 8 bits in QPSK, 16QAM, 64QAM, 256QAM respectively. If we calculate for 64QAM as 6bits since 256QAM not widely spread (check Samsung S7 in T-Mobile). 20MHz ==> 100 PRB ==> 100*168*1000 = 16,800,000 RE in 1 s.

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