2. 5G NR
Numerology
Subcarrier Spacing
In 5G NR, subcarrier spacing of 15, 30, 60, 120 and 240 KHz are
supported
Each numerology is labeled as a parameter (u, mu in Greek). The numerology (u = 0) represents subcarrier
spacing of 15 kHz which is same as LTE. And as you see in the second column the subcarrier spacing other
than 15KHz, for 5G NR.
NOTE: In LTE, there is only type of subcarrier spacing (15 KHz), whereas in NR, multiple types of subcarrier
spacing are available.
3. Frame and Subframe:-
Downlink and uplink transmissions are organized
into frames with 10ms duration, each consisting of
ten subframes of 1ms
Each frame is divided into two equally-sized half-
frames of five subframes each with half-frame 0
consisting of subframes 0 – 4 and half-frame 1
consisting of subframes 5 – 9.
In Total, there are 10 subframes in one frame.
4. •Slot:
Slot length gets different depending on different
subcarrier spacing. The general tendency is that slot
length gets shorter as subcarrier spacing gets wider. This
tendency comes from the nature of OFDM.
Number of slots per subframe varies with carrier spacing
There can be 1, 2, 4, 8, or 16 slots per subframe.
NOTE: In LTE, there are fixed two slots per subframe,
but in NR, no. of slot may vary.
5. •OFDM symbol:
The number of symbols within a slot does not change with the numerology or subcarrier spacing.
OFDM symbols in a slot can be classified as ‘downlink’ (denoted ‘D’), ‘flexible’ (denoted ‘X’), or ‘uplink’ (denoted ‘U’).
In a slot in a downlink frame, the UE shall assume that downlink transmissions only occur in ‘downlink’ or ‘flexible’
symbols.
In a slot in an uplink frame, the UE shall only transmit in ‘uplink’ or ‘flexible’ symbols.
The number of symbols per slot is 14 (in case of Normal CP).
The number of symbols per slot is 12 (in case of Extended CP).
NOTE: In NR slot format, DL and UL assignment changes at a symbol level (in LTE TDD the UL/DL assignment is done
in a subframe level)
