The self Contained slot can be defined as a slot that contains the Downlink part, Uplink part, and a Guard period. It was introduced in 5G-NR and the design system was not available in LTE. This provides flexibility in NR which delivers significantly lower latency when compared to LTE.
In 5G New Radio (NR), a “time slot” refers to a discrete unit of time within the radio frame structure used for the transmission and reception of data. Time slots are an essential concept in wireless communication systems, including 5G NR, as they help organize and manage the flow of data between the base station (gNB) and user devices (UEs).
In 5G NR, the radio frame is divided into subframes, and each subframe contains a fixed number of time slots. The number of slots per subframe depends on the specific numerology used in the 5G NR configuration. For example, in a typical subframe for 30 KHz SCS, there will be two slots in a radio frame. Time slots can be allocated for both uplink (UL) and downlink (DL) communication. In the DL, the gNB transmits data to UEs, while in the UL, UEs send data to the gNB. The gNB dynamically schedules time slots for UL and DL transmissions based on the communication needs of each UE.
3GPP has not defined any term “Self-Contained” type Slot, but it is usually referred to in the industry as illustrated in the below image
In the Self-contained Slot,
- The downlink and uplink are separated by a Guard period.
- So there can be Downlink Self contained slots and uplink self-contained slots.
- Downlink self-contained slot consists of downlink data and its corresponding HARQ feedback.
- The uplink self-contained slot consists of uplink scheduling information and uplink data.