5G NR Numerology | 5G NR Terminology

This page describes 5G NR Numerology or 5G NR Terminology as per 3GPP NR (New Radio) release 15 standards. The 5G NR numerology covers terms related to 5G NR wireless system.

Introduction:
As shown in the figure-1, a frame in 5G NR consists of 10 ms duration. A frame consists of 10 subframes with each having 1ms duration similar to LTE. Each subframe consists of 2μ slots. Each slot can have either 14 (normal CP) or 12 (extended CP) OFDM symbols. All the subcarrier spacing options have 14 OFDM symbols. 60 KHz spacing supports both normal and extended CP types.

5G NR Frame Structure-slot,mini-slot
Figure-1: 5G NR Frame showing frame, subframes and slots

For μ = 0 there are 1 slots per subframe , for μ = 1 there are 2 slots per subframe, for μ = 2 there are 4 slots per subframe and so on. Number of slots per frame is ten times of number of slots per sub frame. Hence for μ = 2, there are 40 slots/frame. 5G NR uses 4096 FFT points which consists of 3300 data subcarriers for maximum bandwidth of 400 MHz.

5G NR Numerology
Table-1 : μ, symbols per slot and slots per frame

RG,RB,RE,5G NR
Figure-2: RG, RB and REs as per μ

5G NR Resource Blocks
Table-2: Number of RBs as per μ and SCS (i.e. Δf)

Subcarrier spacing (KHz) 15 30 60 120 240
Symbol duration (µs) 66.7 33.3 16.7 8.33 4.17
CP duration (µS) 4.7 2.3 1.2 (Normal CP), 4.13 (Extended CP) 0.59 0.29
Max. nominal system BW (MHz) 50 100 100 (sub-6 GHz), 200 (mmwave) 400 400
FFT size (max.) 4096 4096 4096 4096 4096
Symbols per slot 14 14 14 (normal CP), 12 (extended CP) 14 14
Slots per subframe 1 2 4 8 16
Slots per frame 10 20 40 80 160

Table-3: Subcarrier spacing, Number of OFDM symbols and slots

5G NR Numerology | 5G NR Terminology

Following table dscribes terms used in 5G NR numerology as defined in the 3GPP standard.

5G NR Numerology Description
Frequency Range • There are two frequency ranges supported in 5G NR viz. FR1 and FR2.
• FR1 supports frequencies below 6 GHz where as FR2 supports frequencies above 6 GHz (i.e. mmwave range).
• FR1: Frequency range is from 450 to 6000 MHz
• FR2: Frequency range is from 24250 to 52600 MHz
Refer complete 5G NR Frequency Bands >>.
eMBB, mMTC, URLLC eMBB stands for Enhanced Mobile Broadband, mMTC stands for massive Machine Type Communication and URLLC stands for Ultra Reliability and Low Latency Communication. Refer eMBB vs mMTC vs URLLC >>.
Frame a frame in 5G NR consists of 10 ms duration.
Subframe A frame consists of 10 subframes with each having 1ms duration similar to LTE. Each subframe consists of 2μ slots. μ can be any value from 0 to 5.
Slot s mentioned normal slot occupies either 14 (normal CP) or 12 (Extended CP) OFDM symbols. It enables slot based scheduling. One slot is the possible scheduling unit and slot aggregation is also allowed. Slot length scales with subcarrier spacing. Slot length = 1 ms/2μ, Where μ can be any value from 0 to 5.
Mini-slot Mini-slot occupies 2, 4 or 7 OFDM symbols. It enables non-slot based scheduling. It is minimum scheduling unit used in 5G NR. As mentioned mini-slots can occupy as little as 2 OFDM symbols and are variable in length. They can be positioned asynchronously with respect to the beginning of a standard slot.
Subcarrier spacing (SCS), It can be any value from 15/30/60/120/240/480 KHz based on 5G NR numerology parameter, μ which has value 0 to 5. For μ = 0, SCS of 15 KHz is used, for μ = 1, SCS of 30 KHz is used and so on.
Slots per frame and subframe • Slots per subframe depends on μ. For μ = 0 to 5, slots/subframe vary from 1/2/4/8/16/32.
• There are 10 subframes per frame and hence slots per frame is ten times of slots per subframe as mentioned in the table.
OFDM symbol duration (Ts) Ts = 1/SCS, For SCS = 15 KHz, Ts = 1/15x103, Ts = 66.7 µs and so on.
Numerology, μ It is the 5G NR parameter which changes SCS and other system parameters, It is denoted as μ and ranges from 0 to 5.
Resource Grid • The resource grid which consists of number of subcarriers in frequency axis and number of OFDM symbols in time axis is known as resource grid.
• 5G NR supports (Ngrid,x)size,μ X (NSC)RB subcarriers and (Nsymb)subframe,μ OFDM symbols.
Resource Block • RB (Resource Block) consists of total 12 consecutive subcarriers in frequency domain.
• (NSC)RB = 12
• There are more than one RBs in a resource grid.
• Resource elements are grouped into PRB (Physical Resource Blocks). Each PRB consists of 12 subcarriers as mentioned.
Resource Element • Each element in resource grid for antenna port ("p") and subcarrier spacing configuration ("μ") is known as Resource Element.
• It is uniquely identified by (k,l)p,μ, where
k = index in the frequency domain.
l = symbol position in time domain.
Cyclic Prefix type and duration There are two types viz. normal and extended. For normal each slot occupies 14 symbols and for extended each slot occupies 12 symbols. Extended CP type is used for SCS of 60 KHz only.


5G NR Numerology | 5G NR Terminology


5G NR Control channels | 5G NR Traffic Channels | 5G NR Reference Signals and sequences


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