Semi-static and dynamic TDD configuration for 5G-NR
TDD configuration may be dynamically and/or semi-statically signaled to user equipment devices by a base station. Semi-static TDD configuration may include: an initial portion for downlink transmission; a flexible portion; and a terminal portion for uplink transmission. TDD structure of the flexible portion may be determined later by transmission of dynamic physical layer configuration information such as downlink control information (DCI) and/or slot format indicator (SFI). (The SFI may be included in a group common PDCCH of a slot.) The downlink portion and/or the uplink portion may include subsets whose nominal transmit direction is subject to override by transmission of dynamic physical layer configuration information.
1. An apparatus for operating a base station, the apparatus comprising:
a processor configured to cause the base station to:
transmit, to a user equipment device (UE), time division duplex (TDD) configuration information, wherein the TDD configuration information includes parameters that define a semi-static TDD configuration for a frame structure, wherein the parameters include:
a period specifying a duration of the frame structure;
a first length specifying a duration of a downlink portion of the frame structure, wherein the downlink portion occupies an initial position within the frame structure and said first length is specified by the semi-static TDD configuration in terms of slots and symbols, wherein a slot is a specified number of symbols in length; and
a second length specifying a duration of an uplink portion of the frame structure, wherein the uplink portion occupies a terminal position within the frame structure and said second length is specified by the semi-static TDD configuration in terms of slots and symbols;
wherein an intermediate portion of the frame structure occurs after the downlink portion and before the uplink portion, wherein the intermediate portion includes a number of flexible symbols useable for an uplink or downlink direction, wherein a respective direction for each respective symbol of the number of flexible symbols is not determined by the TDD configuration information; and
perform TDD operations including:
transmitting, to the UE, downlink data within the downlink portion of the frame structure; and
receiving, from the UE, uplink data within the uplink portion of the frame structure.
2. The apparatus of claim 1 , wherein the processor is further configured to cause the base station to:
transmit one or more physical layer signals that dynamically indicate a TDD structure of the intermediate portion; and
perform TDD operations over the intermediate portion based on the TDD structure.
3. The apparatus of claim 1 , wherein the processor is further configured to cause the base station to:
perform TDD operations for each frame in a sequence of frames based on the semi-static TDD configuration, wherein, for each of the frames of the sequence, a TDD structure of the intermediate portion of the frame is determined by corresponding dynamic configuration information provided in one or more slots of the frame.
4. The apparatus of claim 1 ,
wherein the downlink portion includes an initial subportion and a following subportion;
wherein the initial subportion is configured for downlink transfer with no possibility of dynamic override to different TDD status;
wherein the following subportion is configured for downlink transfer with possibility of dynamic override to different TDD status.
5. The apparatus of claim 1 , wherein the processor is further configured to cause the base station to:
apply a time shift to a TDD configuration of a second base station operating according to 3GPP LTE.
6. The apparatus of claim 1 , wherein said flexible symbols are in a transition slot, wherein symbols of the transition slot that are neither part of the uplink portion nor the downlink portion are gap symbols.
7. The apparatus of claim 1 , wherein the TDD configuration information does not conflict with transmission direction indicated by dynamic downlink control information (DCI).
8. An apparatus configured for implementation in a user equipment device (UE), the apparatus comprising:
a processor configured to cause the UE to:
receive parameters that define a semi-static TDD configuration, wherein the parameters include:
a period;
a first length specifying a duration of a downlink portion of the period, wherein the downlink portion occupies an initial position within the period, wherein said first length is specified by a first number of whole slots and a second number of symbols, wherein a slot is a specified number of symbols in length; and
a second length specifying a duration of an uplink portion of the period, wherein the uplink portion occupies a terminal position within the period, wherein said second length is specified by a third number of whole slots and a fourth number of symbols;
wherein symbols within the period but not occurring in the downlink portion or the uplink portion comprise a flexible portion, wherein symbols of the flexible portion comprise flexible symbols useable for an uplink or downlink direction; and
receive a physical layer signaling including downlink control information (DCI) that dynamically indicates an uplink or downlink direction of at least one flexible symbol.
9. The apparatus of claim 8 , wherein the parameters further indicate cancellation of one or more periodic transmissions configured by RRC.
10. The apparatus of claim 8 , wherein the DCI is received in a group common control channel.
11. The apparatus of claim 8 , wherein the period is one of: 10 ms, 5 ms, 2 ms, 1 ms, 0.5 ms, 0.25 ms, or 0.125 ms.
12. The apparatus of claim 8 , wherein the DCI comprises a slot format indicator.
13. The apparatus of claim 8 , wherein the physical layer signaling is received once per slot.
14. The apparatus of claim 13 , the processor further configured to cause the UE to:
perform TDD operations over the flexible portion based on the DCI.
15. An apparatus, comprising:
a processor configured to cause a base station to:
transmit, to a user equipment device (UE), parameters that define a semi-static TDD configuration, wherein the parameters include:
a period;
a first length specifying a duration of a downlink portion of the period, wherein the downlink portion occupies an initial position within the period, wherein said first length is specified by a first number of whole slots and a second number of symbols, wherein a slot is a specified number of symbols in length; and
a second length specifying a duration of an uplink portion of the period, wherein the uplink portion occupies a terminal position within the period, wherein said second length is specified by a third number of whole slots and a fourth number of symbols;
wherein symbols within the period but not occurring in the downlink portion or the uplink portion comprise a flexible portion, wherein symbols of the flexible portion comprise flexible symbols useable for an uplink or downlink direction; and
transmit, to the UE, a physical layer signaling including first downlink control information (DCI) that dynamically indicates an uplink or downlink direction of at least one flexible symbol.
16. The apparatus of claim 15 , wherein the physical layer signaling is transmitted once per slot.
17. The apparatus of claim 15 , wherein the DCI is received in a group common control channel.
18. The apparatus of claim 15 ,
wherein the period is one of: 10 ms, 5 ms, 2 ms, 1 ms, 0.5 ms, 0.25 ms, or 0.125 ms.
19. The apparatus of claim 15 , wherein the DCI comprises a slot format indicator.
20. The apparatus of claim 15 , wherein the parameters further indicate cancellation of one or more periodic transmissions configured by RRC.