In 3GPP New Radio (NR), cell phase synchronization is specified as 3µs – that is, the same as for LTE. Allocation of a budget to the different components of the guard period is the result of a trade-off between cost (product and deployment), availability, TDD periodicity and overheads. To decrease overheads, the emphasis is on striving to keep the guard periods short, while still catering for the desired effects. Since guard periods are not used for communication, they reduce the time ratio when spectrum resources can be used.
sufficient time for the UE and base station to change between transmit and receive modes (TRX TX, TX TRX).sufficient transient time when the transmitter changes between defined ON/OFF power levels (TOn Off, TOff On).
The duration of the guard period needs to cater for four effects: Guard periods are used for isolation with a configurable total guard time expressed as an integer number of symbols.