This story only introduces what type of signals used for power control implementation in 5G NR.
5G NR uses both open loop power control and closed loop power control mechanisms. These power control mechanisms in 5G NR uses various kind of signals: DCI, SSS, SRS, SIB1, PUSCH.
DCI
Downlink Control Information (DCI) signals are sent on PDCCH from gNB to CPE. DCI is used by gNB packet scheduler to allocate both UL and DL resources. DCI can also be used to provide uplink power control commands.
SSS:
Secondary Synchronization signals (SSS) used during cell search and beam management procedures. SSS also used for Reference signal received power (RSRP) and Reference signal received quality(RSRQ) measurements. RSRP can also be used for power control calculations.
SRS:
Sound reference signal (SRS) is an uplink reference signal transmitted by UE to gNB. It is a reference signal for gNB to know the channel quality in uplink path. SRS also gives information about the power loss of the transmitted signal.
SIB1:
System Information Block1 (SIB1) is used to broadcast uplink-downlink configuration. SIB1 also known as Remaining Minimum System Information (RMSI) which carries the minimum system information which is required for the UE to access the gNB. This SIB1 also carries power control related configuration.
PUSCH:
Physical Uplink shared channel (PUSCH) that carries user data. UE transmits Msg3 over PUSCH. Msg3 is also called as Scheduled UL transmission or RRC setup request. This Msg3 also carries information elements related to power control.
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