What is Dynamic TDD in 5G?

As in 4G, SIB 1 is used to broadcast an uplink Downlink configuration in 5G as well, but this configuration is not limited to a pattern defined by 3GPP, but the base station can apply its own patterns and 5G also provide the scope to dynamically adjust this configuration using RRC signal or Layer-1 signaling on PDCCH. Dynamic TDD allows a 5G base station to adjust the DL and UL resources as per short term requirement, Neighbor cells reconfigure their UL and DL resources without coordination which means one cell can be transmitting in DL and other NBR cell may be receiving in UL, This generally causes cross link interference.

UE to UE Interference – UL of one cell Causing interference to DL of another NBR cell.

BTS to BTS Interference – DL of one cell Causing Interference to UL of another NBR cell.

This is not applicable to Control regions; All cell Transmit control info ( DCI and UCI) info at same time in same direction, as 5G allows timing of control regions to be configured.

Increased channel code redundancy and retransmission can be used to mitigate cross link interference. Cross link interference is less of an issue on high band which are noise limited rather than interference limited.

Source: Vikas Kumar Nain on LinkedIn: #5g #5gnr #DynamicTDD

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